| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | /* |
| 3 | * linux/kernel/fork.c |
| 4 | * |
| 5 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 6 | */ |
| 7 | |
| 8 | /* |
| 9 | * 'fork.c' contains the help-routines for the 'fork' system call |
| 10 | * (see also entry.S and others). |
| 11 | * Fork is rather simple, once you get the hang of it, but the memory |
| 12 | * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' |
| 13 | */ |
| 14 | |
| 15 | #include <linux/anon_inodes.h> |
| 16 | #include <linux/slab.h> |
| 17 | #include <linux/sched/autogroup.h> |
| 18 | #include <linux/sched/mm.h> |
| 19 | #include <linux/sched/coredump.h> |
| 20 | #include <linux/sched/user.h> |
| 21 | #include <linux/sched/numa_balancing.h> |
| 22 | #include <linux/sched/stat.h> |
| 23 | #include <linux/sched/task.h> |
| 24 | #include <linux/sched/task_stack.h> |
| 25 | #include <linux/sched/cputime.h> |
| 26 | #include <linux/seq_file.h> |
| 27 | #include <linux/rtmutex.h> |
| 28 | #include <linux/init.h> |
| 29 | #include <linux/unistd.h> |
| 30 | #include <linux/module.h> |
| 31 | #include <linux/vmalloc.h> |
| 32 | #include <linux/completion.h> |
| 33 | #include <linux/personality.h> |
| 34 | #include <linux/mempolicy.h> |
| 35 | #include <linux/sem.h> |
| 36 | #include <linux/file.h> |
| 37 | #include <linux/fdtable.h> |
| 38 | #include <linux/iocontext.h> |
| 39 | #include <linux/key.h> |
| 40 | #include <linux/binfmts.h> |
| 41 | #include <linux/mman.h> |
| 42 | #include <linux/mmu_notifier.h> |
| 43 | #include <linux/fs.h> |
| 44 | #include <linux/mm.h> |
| 45 | #include <linux/mm_inline.h> |
| 46 | #include <linux/vmacache.h> |
| 47 | #include <linux/nsproxy.h> |
| 48 | #include <linux/capability.h> |
| 49 | #include <linux/cpu.h> |
| 50 | #include <linux/cgroup.h> |
| 51 | #include <linux/security.h> |
| 52 | #include <linux/hugetlb.h> |
| 53 | #include <linux/seccomp.h> |
| 54 | #include <linux/swap.h> |
| 55 | #include <linux/syscalls.h> |
| 56 | #include <linux/jiffies.h> |
| 57 | #include <linux/futex.h> |
| 58 | #include <linux/compat.h> |
| 59 | #include <linux/kthread.h> |
| 60 | #include <linux/task_io_accounting_ops.h> |
| 61 | #include <linux/rcupdate.h> |
| 62 | #include <linux/ptrace.h> |
| 63 | #include <linux/mount.h> |
| 64 | #include <linux/audit.h> |
| 65 | #include <linux/memcontrol.h> |
| 66 | #include <linux/ftrace.h> |
| 67 | #include <linux/proc_fs.h> |
| 68 | #include <linux/profile.h> |
| 69 | #include <linux/rmap.h> |
| 70 | #include <linux/ksm.h> |
| 71 | #include <linux/acct.h> |
| 72 | #include <linux/userfaultfd_k.h> |
| 73 | #include <linux/tsacct_kern.h> |
| 74 | #include <linux/cn_proc.h> |
| 75 | #include <linux/freezer.h> |
| 76 | #include <linux/delayacct.h> |
| 77 | #include <linux/taskstats_kern.h> |
| 78 | #include <linux/random.h> |
| 79 | #include <linux/tty.h> |
| 80 | #include <linux/fs_struct.h> |
| 81 | #include <linux/magic.h> |
| 82 | #include <linux/perf_event.h> |
| 83 | #include <linux/posix-timers.h> |
| 84 | #include <linux/user-return-notifier.h> |
| 85 | #include <linux/oom.h> |
| 86 | #include <linux/khugepaged.h> |
| 87 | #include <linux/signalfd.h> |
| 88 | #include <linux/uprobes.h> |
| 89 | #include <linux/aio.h> |
| 90 | #include <linux/compiler.h> |
| 91 | #include <linux/sysctl.h> |
| 92 | #include <linux/kcov.h> |
| 93 | #include <linux/livepatch.h> |
| 94 | #include <linux/thread_info.h> |
| 95 | #include <linux/stackleak.h> |
| 96 | #include <linux/kasan.h> |
| 97 | #include <linux/scs.h> |
| 98 | #include <linux/io_uring.h> |
| 99 | #include <linux/bpf.h> |
| 100 | #include <linux/sched/mm.h> |
| 101 | |
| 102 | #include <asm/pgalloc.h> |
| 103 | #include <linux/uaccess.h> |
| 104 | #include <asm/mmu_context.h> |
| 105 | #include <asm/cacheflush.h> |
| 106 | #include <asm/tlbflush.h> |
| 107 | |
| 108 | #include <trace/events/sched.h> |
| 109 | |
| 110 | #define CREATE_TRACE_POINTS |
| 111 | #include <trace/events/task.h> |
| 112 | |
| 113 | /* |
| 114 | * Minimum number of threads to boot the kernel |
| 115 | */ |
| 116 | #define MIN_THREADS 20 |
| 117 | |
| 118 | /* |
| 119 | * Maximum number of threads |
| 120 | */ |
| 121 | #define MAX_THREADS FUTEX_TID_MASK |
| 122 | |
| 123 | /* |
| 124 | * Protected counters by write_lock_irq(&tasklist_lock) |
| 125 | */ |
| 126 | unsigned long total_forks; /* Handle normal Linux uptimes. */ |
| 127 | int nr_threads; /* The idle threads do not count.. */ |
| 128 | |
| 129 | static int max_threads; /* tunable limit on nr_threads */ |
| 130 | |
| 131 | #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x) |
| 132 | |
| 133 | static const char * const resident_page_types[] = { |
| 134 | NAMED_ARRAY_INDEX(MM_FILEPAGES), |
| 135 | NAMED_ARRAY_INDEX(MM_ANONPAGES), |
| 136 | NAMED_ARRAY_INDEX(MM_SWAPENTS), |
| 137 | NAMED_ARRAY_INDEX(MM_SHMEMPAGES), |
| 138 | }; |
| 139 | |
| 140 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; |
| 141 | |
| 142 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ |
| 143 | |
| 144 | #ifdef CONFIG_PROVE_RCU |
| 145 | int lockdep_tasklist_lock_is_held(void) |
| 146 | { |
| 147 | return lockdep_is_held(&tasklist_lock); |
| 148 | } |
| 149 | EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); |
| 150 | #endif /* #ifdef CONFIG_PROVE_RCU */ |
| 151 | |
| 152 | int nr_processes(void) |
| 153 | { |
| 154 | int cpu; |
| 155 | int total = 0; |
| 156 | |
| 157 | for_each_possible_cpu(cpu) |
| 158 | total += per_cpu(process_counts, cpu); |
| 159 | |
| 160 | return total; |
| 161 | } |
| 162 | |
| 163 | void __weak arch_release_task_struct(struct task_struct *tsk) |
| 164 | { |
| 165 | } |
| 166 | |
| 167 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR |
| 168 | static struct kmem_cache *task_struct_cachep; |
| 169 | |
| 170 | static inline struct task_struct *alloc_task_struct_node(int node) |
| 171 | { |
| 172 | return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node); |
| 173 | } |
| 174 | |
| 175 | static inline void free_task_struct(struct task_struct *tsk) |
| 176 | { |
| 177 | kmem_cache_free(task_struct_cachep, tsk); |
| 178 | } |
| 179 | #endif |
| 180 | |
| 181 | #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR |
| 182 | |
| 183 | /* |
| 184 | * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a |
| 185 | * kmemcache based allocator. |
| 186 | */ |
| 187 | # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) |
| 188 | |
| 189 | # ifdef CONFIG_VMAP_STACK |
| 190 | /* |
| 191 | * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB |
| 192 | * flush. Try to minimize the number of calls by caching stacks. |
| 193 | */ |
| 194 | #define NR_CACHED_STACKS 2 |
| 195 | static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]); |
| 196 | |
| 197 | struct vm_stack { |
| 198 | struct rcu_head rcu; |
| 199 | struct vm_struct *stack_vm_area; |
| 200 | }; |
| 201 | |
| 202 | static bool try_release_thread_stack_to_cache(struct vm_struct *vm) |
| 203 | { |
| 204 | unsigned int i; |
| 205 | |
| 206 | for (i = 0; i < NR_CACHED_STACKS; i++) { |
| 207 | if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL) |
| 208 | continue; |
| 209 | return true; |
| 210 | } |
| 211 | return false; |
| 212 | } |
| 213 | |
| 214 | static void thread_stack_free_rcu(struct rcu_head *rh) |
| 215 | { |
| 216 | struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu); |
| 217 | |
| 218 | if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area)) |
| 219 | return; |
| 220 | |
| 221 | vfree(vm_stack); |
| 222 | } |
| 223 | |
| 224 | static void thread_stack_delayed_free(struct task_struct *tsk) |
| 225 | { |
| 226 | struct vm_stack *vm_stack = tsk->stack; |
| 227 | |
| 228 | vm_stack->stack_vm_area = tsk->stack_vm_area; |
| 229 | call_rcu(&vm_stack->rcu, thread_stack_free_rcu); |
| 230 | } |
| 231 | |
| 232 | static int free_vm_stack_cache(unsigned int cpu) |
| 233 | { |
| 234 | struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu); |
| 235 | int i; |
| 236 | |
| 237 | for (i = 0; i < NR_CACHED_STACKS; i++) { |
| 238 | struct vm_struct *vm_stack = cached_vm_stacks[i]; |
| 239 | |
| 240 | if (!vm_stack) |
| 241 | continue; |
| 242 | |
| 243 | vfree(vm_stack->addr); |
| 244 | cached_vm_stacks[i] = NULL; |
| 245 | } |
| 246 | |
| 247 | return 0; |
| 248 | } |
| 249 | |
| 250 | static int memcg_charge_kernel_stack(struct vm_struct *vm) |
| 251 | { |
| 252 | int i; |
| 253 | int ret; |
| 254 | |
| 255 | BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0); |
| 256 | BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE); |
| 257 | |
| 258 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) { |
| 259 | ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0); |
| 260 | if (ret) |
| 261 | goto err; |
| 262 | } |
| 263 | return 0; |
| 264 | err: |
| 265 | /* |
| 266 | * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is |
| 267 | * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will |
| 268 | * ignore this page. |
| 269 | */ |
| 270 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) |
| 271 | memcg_kmem_uncharge_page(vm->pages[i], 0); |
| 272 | return ret; |
| 273 | } |
| 274 | |
| 275 | static int alloc_thread_stack_node(struct task_struct *tsk, int node) |
| 276 | { |
| 277 | struct vm_struct *vm; |
| 278 | void *stack; |
| 279 | int i; |
| 280 | |
| 281 | for (i = 0; i < NR_CACHED_STACKS; i++) { |
| 282 | struct vm_struct *s; |
| 283 | |
| 284 | s = this_cpu_xchg(cached_stacks[i], NULL); |
| 285 | |
| 286 | if (!s) |
| 287 | continue; |
| 288 | |
| 289 | /* Reset stack metadata. */ |
| 290 | kasan_unpoison_range(s->addr, THREAD_SIZE); |
| 291 | |
| 292 | stack = kasan_reset_tag(s->addr); |
| 293 | |
| 294 | /* Clear stale pointers from reused stack. */ |
| 295 | memset(stack, 0, THREAD_SIZE); |
| 296 | |
| 297 | if (memcg_charge_kernel_stack(s)) { |
| 298 | vfree(s->addr); |
| 299 | return -ENOMEM; |
| 300 | } |
| 301 | |
| 302 | tsk->stack_vm_area = s; |
| 303 | tsk->stack = stack; |
| 304 | return 0; |
| 305 | } |
| 306 | |
| 307 | /* |
| 308 | * Allocated stacks are cached and later reused by new threads, |
| 309 | * so memcg accounting is performed manually on assigning/releasing |
| 310 | * stacks to tasks. Drop __GFP_ACCOUNT. |
| 311 | */ |
| 312 | stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN, |
| 313 | VMALLOC_START, VMALLOC_END, |
| 314 | THREADINFO_GFP & ~__GFP_ACCOUNT, |
| 315 | PAGE_KERNEL, |
| 316 | 0, node, __builtin_return_address(0)); |
| 317 | if (!stack) |
| 318 | return -ENOMEM; |
| 319 | |
| 320 | vm = find_vm_area(stack); |
| 321 | if (memcg_charge_kernel_stack(vm)) { |
| 322 | vfree(stack); |
| 323 | return -ENOMEM; |
| 324 | } |
| 325 | /* |
| 326 | * We can't call find_vm_area() in interrupt context, and |
| 327 | * free_thread_stack() can be called in interrupt context, |
| 328 | * so cache the vm_struct. |
| 329 | */ |
| 330 | tsk->stack_vm_area = vm; |
| 331 | stack = kasan_reset_tag(stack); |
| 332 | tsk->stack = stack; |
| 333 | return 0; |
| 334 | } |
| 335 | |
| 336 | static void free_thread_stack(struct task_struct *tsk) |
| 337 | { |
| 338 | if (!try_release_thread_stack_to_cache(tsk->stack_vm_area)) |
| 339 | thread_stack_delayed_free(tsk); |
| 340 | |
| 341 | tsk->stack = NULL; |
| 342 | tsk->stack_vm_area = NULL; |
| 343 | } |
| 344 | |
| 345 | # else /* !CONFIG_VMAP_STACK */ |
| 346 | |
| 347 | static void thread_stack_free_rcu(struct rcu_head *rh) |
| 348 | { |
| 349 | __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER); |
| 350 | } |
| 351 | |
| 352 | static void thread_stack_delayed_free(struct task_struct *tsk) |
| 353 | { |
| 354 | struct rcu_head *rh = tsk->stack; |
| 355 | |
| 356 | call_rcu(rh, thread_stack_free_rcu); |
| 357 | } |
| 358 | |
| 359 | static int alloc_thread_stack_node(struct task_struct *tsk, int node) |
| 360 | { |
| 361 | struct page *page = alloc_pages_node(node, THREADINFO_GFP, |
| 362 | THREAD_SIZE_ORDER); |
| 363 | |
| 364 | if (likely(page)) { |
| 365 | tsk->stack = kasan_reset_tag(page_address(page)); |
| 366 | return 0; |
| 367 | } |
| 368 | return -ENOMEM; |
| 369 | } |
| 370 | |
| 371 | static void free_thread_stack(struct task_struct *tsk) |
| 372 | { |
| 373 | thread_stack_delayed_free(tsk); |
| 374 | tsk->stack = NULL; |
| 375 | } |
| 376 | |
| 377 | # endif /* CONFIG_VMAP_STACK */ |
| 378 | # else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */ |
| 379 | |
| 380 | static struct kmem_cache *thread_stack_cache; |
| 381 | |
| 382 | static void thread_stack_free_rcu(struct rcu_head *rh) |
| 383 | { |
| 384 | kmem_cache_free(thread_stack_cache, rh); |
| 385 | } |
| 386 | |
| 387 | static void thread_stack_delayed_free(struct task_struct *tsk) |
| 388 | { |
| 389 | struct rcu_head *rh = tsk->stack; |
| 390 | |
| 391 | call_rcu(rh, thread_stack_free_rcu); |
| 392 | } |
| 393 | |
| 394 | static int alloc_thread_stack_node(struct task_struct *tsk, int node) |
| 395 | { |
| 396 | unsigned long *stack; |
| 397 | stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node); |
| 398 | stack = kasan_reset_tag(stack); |
| 399 | tsk->stack = stack; |
| 400 | return stack ? 0 : -ENOMEM; |
| 401 | } |
| 402 | |
| 403 | static void free_thread_stack(struct task_struct *tsk) |
| 404 | { |
| 405 | thread_stack_delayed_free(tsk); |
| 406 | tsk->stack = NULL; |
| 407 | } |
| 408 | |
| 409 | void thread_stack_cache_init(void) |
| 410 | { |
| 411 | thread_stack_cache = kmem_cache_create_usercopy("thread_stack", |
| 412 | THREAD_SIZE, THREAD_SIZE, 0, 0, |
| 413 | THREAD_SIZE, NULL); |
| 414 | BUG_ON(thread_stack_cache == NULL); |
| 415 | } |
| 416 | |
| 417 | # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */ |
| 418 | #else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */ |
| 419 | |
| 420 | static int alloc_thread_stack_node(struct task_struct *tsk, int node) |
| 421 | { |
| 422 | unsigned long *stack; |
| 423 | |
| 424 | stack = arch_alloc_thread_stack_node(tsk, node); |
| 425 | tsk->stack = stack; |
| 426 | return stack ? 0 : -ENOMEM; |
| 427 | } |
| 428 | |
| 429 | static void free_thread_stack(struct task_struct *tsk) |
| 430 | { |
| 431 | arch_free_thread_stack(tsk); |
| 432 | tsk->stack = NULL; |
| 433 | } |
| 434 | |
| 435 | #endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */ |
| 436 | |
| 437 | /* SLAB cache for signal_struct structures (tsk->signal) */ |
| 438 | static struct kmem_cache *signal_cachep; |
| 439 | |
| 440 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ |
| 441 | struct kmem_cache *sighand_cachep; |
| 442 | |
| 443 | /* SLAB cache for files_struct structures (tsk->files) */ |
| 444 | struct kmem_cache *files_cachep; |
| 445 | |
| 446 | /* SLAB cache for fs_struct structures (tsk->fs) */ |
| 447 | struct kmem_cache *fs_cachep; |
| 448 | |
| 449 | /* SLAB cache for vm_area_struct structures */ |
| 450 | static struct kmem_cache *vm_area_cachep; |
| 451 | |
| 452 | /* SLAB cache for mm_struct structures (tsk->mm) */ |
| 453 | static struct kmem_cache *mm_cachep; |
| 454 | |
| 455 | struct vm_area_struct *vm_area_alloc(struct mm_struct *mm) |
| 456 | { |
| 457 | struct vm_area_struct *vma; |
| 458 | |
| 459 | vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
| 460 | if (vma) |
| 461 | vma_init(vma, mm); |
| 462 | return vma; |
| 463 | } |
| 464 | |
| 465 | struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) |
| 466 | { |
| 467 | struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
| 468 | |
| 469 | if (new) { |
| 470 | ASSERT_EXCLUSIVE_WRITER(orig->vm_flags); |
| 471 | ASSERT_EXCLUSIVE_WRITER(orig->vm_file); |
| 472 | /* |
| 473 | * orig->shared.rb may be modified concurrently, but the clone |
| 474 | * will be reinitialized. |
| 475 | */ |
| 476 | *new = data_race(*orig); |
| 477 | INIT_LIST_HEAD(&new->anon_vma_chain); |
| 478 | new->vm_next = new->vm_prev = NULL; |
| 479 | dup_anon_vma_name(orig, new); |
| 480 | } |
| 481 | return new; |
| 482 | } |
| 483 | |
| 484 | void vm_area_free(struct vm_area_struct *vma) |
| 485 | { |
| 486 | free_anon_vma_name(vma); |
| 487 | kmem_cache_free(vm_area_cachep, vma); |
| 488 | } |
| 489 | |
| 490 | static void account_kernel_stack(struct task_struct *tsk, int account) |
| 491 | { |
| 492 | if (IS_ENABLED(CONFIG_VMAP_STACK)) { |
| 493 | struct vm_struct *vm = task_stack_vm_area(tsk); |
| 494 | int i; |
| 495 | |
| 496 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) |
| 497 | mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB, |
| 498 | account * (PAGE_SIZE / 1024)); |
| 499 | } else { |
| 500 | void *stack = task_stack_page(tsk); |
| 501 | |
| 502 | /* All stack pages are in the same node. */ |
| 503 | mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB, |
| 504 | account * (THREAD_SIZE / 1024)); |
| 505 | } |
| 506 | } |
| 507 | |
| 508 | void exit_task_stack_account(struct task_struct *tsk) |
| 509 | { |
| 510 | account_kernel_stack(tsk, -1); |
| 511 | |
| 512 | if (IS_ENABLED(CONFIG_VMAP_STACK)) { |
| 513 | struct vm_struct *vm; |
| 514 | int i; |
| 515 | |
| 516 | vm = task_stack_vm_area(tsk); |
| 517 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) |
| 518 | memcg_kmem_uncharge_page(vm->pages[i], 0); |
| 519 | } |
| 520 | } |
| 521 | |
| 522 | static void release_task_stack(struct task_struct *tsk) |
| 523 | { |
| 524 | if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD)) |
| 525 | return; /* Better to leak the stack than to free prematurely */ |
| 526 | |
| 527 | free_thread_stack(tsk); |
| 528 | } |
| 529 | |
| 530 | #ifdef CONFIG_THREAD_INFO_IN_TASK |
| 531 | void put_task_stack(struct task_struct *tsk) |
| 532 | { |
| 533 | if (refcount_dec_and_test(&tsk->stack_refcount)) |
| 534 | release_task_stack(tsk); |
| 535 | } |
| 536 | #endif |
| 537 | |
| 538 | void free_task(struct task_struct *tsk) |
| 539 | { |
| 540 | release_user_cpus_ptr(tsk); |
| 541 | scs_release(tsk); |
| 542 | |
| 543 | #ifndef CONFIG_THREAD_INFO_IN_TASK |
| 544 | /* |
| 545 | * The task is finally done with both the stack and thread_info, |
| 546 | * so free both. |
| 547 | */ |
| 548 | release_task_stack(tsk); |
| 549 | #else |
| 550 | /* |
| 551 | * If the task had a separate stack allocation, it should be gone |
| 552 | * by now. |
| 553 | */ |
| 554 | WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0); |
| 555 | #endif |
| 556 | rt_mutex_debug_task_free(tsk); |
| 557 | ftrace_graph_exit_task(tsk); |
| 558 | arch_release_task_struct(tsk); |
| 559 | if (tsk->flags & PF_KTHREAD) |
| 560 | free_kthread_struct(tsk); |
| 561 | free_task_struct(tsk); |
| 562 | } |
| 563 | EXPORT_SYMBOL(free_task); |
| 564 | |
| 565 | static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm) |
| 566 | { |
| 567 | struct file *exe_file; |
| 568 | |
| 569 | exe_file = get_mm_exe_file(oldmm); |
| 570 | RCU_INIT_POINTER(mm->exe_file, exe_file); |
| 571 | /* |
| 572 | * We depend on the oldmm having properly denied write access to the |
| 573 | * exe_file already. |
| 574 | */ |
| 575 | if (exe_file && deny_write_access(exe_file)) |
| 576 | pr_warn_once("deny_write_access() failed in %s\n", __func__); |
| 577 | } |
| 578 | |
| 579 | #ifdef CONFIG_MMU |
| 580 | static __latent_entropy int dup_mmap(struct mm_struct *mm, |
| 581 | struct mm_struct *oldmm) |
| 582 | { |
| 583 | struct vm_area_struct *mpnt, *tmp, *prev, **pprev; |
| 584 | struct rb_node **rb_link, *rb_parent; |
| 585 | int retval; |
| 586 | unsigned long charge; |
| 587 | LIST_HEAD(uf); |
| 588 | |
| 589 | uprobe_start_dup_mmap(); |
| 590 | if (mmap_write_lock_killable(oldmm)) { |
| 591 | retval = -EINTR; |
| 592 | goto fail_uprobe_end; |
| 593 | } |
| 594 | flush_cache_dup_mm(oldmm); |
| 595 | uprobe_dup_mmap(oldmm, mm); |
| 596 | /* |
| 597 | * Not linked in yet - no deadlock potential: |
| 598 | */ |
| 599 | mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING); |
| 600 | |
| 601 | /* No ordering required: file already has been exposed. */ |
| 602 | dup_mm_exe_file(mm, oldmm); |
| 603 | |
| 604 | mm->total_vm = oldmm->total_vm; |
| 605 | mm->data_vm = oldmm->data_vm; |
| 606 | mm->exec_vm = oldmm->exec_vm; |
| 607 | mm->stack_vm = oldmm->stack_vm; |
| 608 | |
| 609 | rb_link = &mm->mm_rb.rb_node; |
| 610 | rb_parent = NULL; |
| 611 | pprev = &mm->mmap; |
| 612 | retval = ksm_fork(mm, oldmm); |
| 613 | if (retval) |
| 614 | goto out; |
| 615 | retval = khugepaged_fork(mm, oldmm); |
| 616 | if (retval) |
| 617 | goto out; |
| 618 | |
| 619 | prev = NULL; |
| 620 | for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { |
| 621 | struct file *file; |
| 622 | |
| 623 | if (mpnt->vm_flags & VM_DONTCOPY) { |
| 624 | vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt)); |
| 625 | continue; |
| 626 | } |
| 627 | charge = 0; |
| 628 | /* |
| 629 | * Don't duplicate many vmas if we've been oom-killed (for |
| 630 | * example) |
| 631 | */ |
| 632 | if (fatal_signal_pending(current)) { |
| 633 | retval = -EINTR; |
| 634 | goto out; |
| 635 | } |
| 636 | if (mpnt->vm_flags & VM_ACCOUNT) { |
| 637 | unsigned long len = vma_pages(mpnt); |
| 638 | |
| 639 | if (security_vm_enough_memory_mm(oldmm, len)) /* sic */ |
| 640 | goto fail_nomem; |
| 641 | charge = len; |
| 642 | } |
| 643 | tmp = vm_area_dup(mpnt); |
| 644 | if (!tmp) |
| 645 | goto fail_nomem; |
| 646 | retval = vma_dup_policy(mpnt, tmp); |
| 647 | if (retval) |
| 648 | goto fail_nomem_policy; |
| 649 | tmp->vm_mm = mm; |
| 650 | retval = dup_userfaultfd(tmp, &uf); |
| 651 | if (retval) |
| 652 | goto fail_nomem_anon_vma_fork; |
| 653 | if (tmp->vm_flags & VM_WIPEONFORK) { |
| 654 | /* |
| 655 | * VM_WIPEONFORK gets a clean slate in the child. |
| 656 | * Don't prepare anon_vma until fault since we don't |
| 657 | * copy page for current vma. |
| 658 | */ |
| 659 | tmp->anon_vma = NULL; |
| 660 | } else if (anon_vma_fork(tmp, mpnt)) |
| 661 | goto fail_nomem_anon_vma_fork; |
| 662 | tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT); |
| 663 | file = tmp->vm_file; |
| 664 | if (file) { |
| 665 | struct address_space *mapping = file->f_mapping; |
| 666 | |
| 667 | get_file(file); |
| 668 | i_mmap_lock_write(mapping); |
| 669 | if (tmp->vm_flags & VM_SHARED) |
| 670 | mapping_allow_writable(mapping); |
| 671 | flush_dcache_mmap_lock(mapping); |
| 672 | /* insert tmp into the share list, just after mpnt */ |
| 673 | vma_interval_tree_insert_after(tmp, mpnt, |
| 674 | &mapping->i_mmap); |
| 675 | flush_dcache_mmap_unlock(mapping); |
| 676 | i_mmap_unlock_write(mapping); |
| 677 | } |
| 678 | |
| 679 | /* |
| 680 | * Clear hugetlb-related page reserves for children. This only |
| 681 | * affects MAP_PRIVATE mappings. Faults generated by the child |
| 682 | * are not guaranteed to succeed, even if read-only |
| 683 | */ |
| 684 | if (is_vm_hugetlb_page(tmp)) |
| 685 | reset_vma_resv_huge_pages(tmp); |
| 686 | |
| 687 | /* |
| 688 | * Link in the new vma and copy the page table entries. |
| 689 | */ |
| 690 | *pprev = tmp; |
| 691 | pprev = &tmp->vm_next; |
| 692 | tmp->vm_prev = prev; |
| 693 | prev = tmp; |
| 694 | |
| 695 | __vma_link_rb(mm, tmp, rb_link, rb_parent); |
| 696 | rb_link = &tmp->vm_rb.rb_right; |
| 697 | rb_parent = &tmp->vm_rb; |
| 698 | |
| 699 | mm->map_count++; |
| 700 | if (!(tmp->vm_flags & VM_WIPEONFORK)) |
| 701 | retval = copy_page_range(tmp, mpnt); |
| 702 | |
| 703 | if (tmp->vm_ops && tmp->vm_ops->open) |
| 704 | tmp->vm_ops->open(tmp); |
| 705 | |
| 706 | if (retval) |
| 707 | goto out; |
| 708 | } |
| 709 | /* a new mm has just been created */ |
| 710 | retval = arch_dup_mmap(oldmm, mm); |
| 711 | out: |
| 712 | mmap_write_unlock(mm); |
| 713 | flush_tlb_mm(oldmm); |
| 714 | mmap_write_unlock(oldmm); |
| 715 | dup_userfaultfd_complete(&uf); |
| 716 | fail_uprobe_end: |
| 717 | uprobe_end_dup_mmap(); |
| 718 | return retval; |
| 719 | fail_nomem_anon_vma_fork: |
| 720 | mpol_put(vma_policy(tmp)); |
| 721 | fail_nomem_policy: |
| 722 | vm_area_free(tmp); |
| 723 | fail_nomem: |
| 724 | retval = -ENOMEM; |
| 725 | vm_unacct_memory(charge); |
| 726 | goto out; |
| 727 | } |
| 728 | |
| 729 | static inline int mm_alloc_pgd(struct mm_struct *mm) |
| 730 | { |
| 731 | mm->pgd = pgd_alloc(mm); |
| 732 | if (unlikely(!mm->pgd)) |
| 733 | return -ENOMEM; |
| 734 | return 0; |
| 735 | } |
| 736 | |
| 737 | static inline void mm_free_pgd(struct mm_struct *mm) |
| 738 | { |
| 739 | pgd_free(mm, mm->pgd); |
| 740 | } |
| 741 | #else |
| 742 | static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) |
| 743 | { |
| 744 | mmap_write_lock(oldmm); |
| 745 | dup_mm_exe_file(mm, oldmm); |
| 746 | mmap_write_unlock(oldmm); |
| 747 | return 0; |
| 748 | } |
| 749 | #define mm_alloc_pgd(mm) (0) |
| 750 | #define mm_free_pgd(mm) |
| 751 | #endif /* CONFIG_MMU */ |
| 752 | |
| 753 | static void check_mm(struct mm_struct *mm) |
| 754 | { |
| 755 | int i; |
| 756 | |
| 757 | BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS, |
| 758 | "Please make sure 'struct resident_page_types[]' is updated as well"); |
| 759 | |
| 760 | for (i = 0; i < NR_MM_COUNTERS; i++) { |
| 761 | long x = atomic_long_read(&mm->rss_stat.count[i]); |
| 762 | |
| 763 | if (unlikely(x)) |
| 764 | pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n", |
| 765 | mm, resident_page_types[i], x); |
| 766 | } |
| 767 | |
| 768 | if (mm_pgtables_bytes(mm)) |
| 769 | pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n", |
| 770 | mm_pgtables_bytes(mm)); |
| 771 | |
| 772 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS |
| 773 | VM_BUG_ON_MM(mm->pmd_huge_pte, mm); |
| 774 | #endif |
| 775 | } |
| 776 | |
| 777 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) |
| 778 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) |
| 779 | |
| 780 | /* |
| 781 | * Called when the last reference to the mm |
| 782 | * is dropped: either by a lazy thread or by |
| 783 | * mmput. Free the page directory and the mm. |
| 784 | */ |
| 785 | void __mmdrop(struct mm_struct *mm) |
| 786 | { |
| 787 | BUG_ON(mm == &init_mm); |
| 788 | WARN_ON_ONCE(mm == current->mm); |
| 789 | WARN_ON_ONCE(mm == current->active_mm); |
| 790 | mm_free_pgd(mm); |
| 791 | destroy_context(mm); |
| 792 | mmu_notifier_subscriptions_destroy(mm); |
| 793 | check_mm(mm); |
| 794 | put_user_ns(mm->user_ns); |
| 795 | free_mm(mm); |
| 796 | } |
| 797 | EXPORT_SYMBOL_GPL(__mmdrop); |
| 798 | |
| 799 | static void mmdrop_async_fn(struct work_struct *work) |
| 800 | { |
| 801 | struct mm_struct *mm; |
| 802 | |
| 803 | mm = container_of(work, struct mm_struct, async_put_work); |
| 804 | __mmdrop(mm); |
| 805 | } |
| 806 | |
| 807 | static void mmdrop_async(struct mm_struct *mm) |
| 808 | { |
| 809 | if (unlikely(atomic_dec_and_test(&mm->mm_count))) { |
| 810 | INIT_WORK(&mm->async_put_work, mmdrop_async_fn); |
| 811 | schedule_work(&mm->async_put_work); |
| 812 | } |
| 813 | } |
| 814 | |
| 815 | static inline void free_signal_struct(struct signal_struct *sig) |
| 816 | { |
| 817 | taskstats_tgid_free(sig); |
| 818 | sched_autogroup_exit(sig); |
| 819 | /* |
| 820 | * __mmdrop is not safe to call from softirq context on x86 due to |
| 821 | * pgd_dtor so postpone it to the async context |
| 822 | */ |
| 823 | if (sig->oom_mm) |
| 824 | mmdrop_async(sig->oom_mm); |
| 825 | kmem_cache_free(signal_cachep, sig); |
| 826 | } |
| 827 | |
| 828 | static inline void put_signal_struct(struct signal_struct *sig) |
| 829 | { |
| 830 | if (refcount_dec_and_test(&sig->sigcnt)) |
| 831 | free_signal_struct(sig); |
| 832 | } |
| 833 | |
| 834 | void __put_task_struct(struct task_struct *tsk) |
| 835 | { |
| 836 | WARN_ON(!tsk->exit_state); |
| 837 | WARN_ON(refcount_read(&tsk->usage)); |
| 838 | WARN_ON(tsk == current); |
| 839 | |
| 840 | io_uring_free(tsk); |
| 841 | cgroup_free(tsk); |
| 842 | task_numa_free(tsk, true); |
| 843 | security_task_free(tsk); |
| 844 | bpf_task_storage_free(tsk); |
| 845 | exit_creds(tsk); |
| 846 | delayacct_tsk_free(tsk); |
| 847 | put_signal_struct(tsk->signal); |
| 848 | sched_core_free(tsk); |
| 849 | free_task(tsk); |
| 850 | } |
| 851 | EXPORT_SYMBOL_GPL(__put_task_struct); |
| 852 | |
| 853 | void __init __weak arch_task_cache_init(void) { } |
| 854 | |
| 855 | /* |
| 856 | * set_max_threads |
| 857 | */ |
| 858 | static void set_max_threads(unsigned int max_threads_suggested) |
| 859 | { |
| 860 | u64 threads; |
| 861 | unsigned long nr_pages = totalram_pages(); |
| 862 | |
| 863 | /* |
| 864 | * The number of threads shall be limited such that the thread |
| 865 | * structures may only consume a small part of the available memory. |
| 866 | */ |
| 867 | if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64) |
| 868 | threads = MAX_THREADS; |
| 869 | else |
| 870 | threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE, |
| 871 | (u64) THREAD_SIZE * 8UL); |
| 872 | |
| 873 | if (threads > max_threads_suggested) |
| 874 | threads = max_threads_suggested; |
| 875 | |
| 876 | max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS); |
| 877 | } |
| 878 | |
| 879 | #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT |
| 880 | /* Initialized by the architecture: */ |
| 881 | int arch_task_struct_size __read_mostly; |
| 882 | #endif |
| 883 | |
| 884 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR |
| 885 | static void task_struct_whitelist(unsigned long *offset, unsigned long *size) |
| 886 | { |
| 887 | /* Fetch thread_struct whitelist for the architecture. */ |
| 888 | arch_thread_struct_whitelist(offset, size); |
| 889 | |
| 890 | /* |
| 891 | * Handle zero-sized whitelist or empty thread_struct, otherwise |
| 892 | * adjust offset to position of thread_struct in task_struct. |
| 893 | */ |
| 894 | if (unlikely(*size == 0)) |
| 895 | *offset = 0; |
| 896 | else |
| 897 | *offset += offsetof(struct task_struct, thread); |
| 898 | } |
| 899 | #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */ |
| 900 | |
| 901 | void __init fork_init(void) |
| 902 | { |
| 903 | int i; |
| 904 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR |
| 905 | #ifndef ARCH_MIN_TASKALIGN |
| 906 | #define ARCH_MIN_TASKALIGN 0 |
| 907 | #endif |
| 908 | int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN); |
| 909 | unsigned long useroffset, usersize; |
| 910 | |
| 911 | /* create a slab on which task_structs can be allocated */ |
| 912 | task_struct_whitelist(&useroffset, &usersize); |
| 913 | task_struct_cachep = kmem_cache_create_usercopy("task_struct", |
| 914 | arch_task_struct_size, align, |
| 915 | SLAB_PANIC|SLAB_ACCOUNT, |
| 916 | useroffset, usersize, NULL); |
| 917 | #endif |
| 918 | |
| 919 | /* do the arch specific task caches init */ |
| 920 | arch_task_cache_init(); |
| 921 | |
| 922 | set_max_threads(MAX_THREADS); |
| 923 | |
| 924 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; |
| 925 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; |
| 926 | init_task.signal->rlim[RLIMIT_SIGPENDING] = |
| 927 | init_task.signal->rlim[RLIMIT_NPROC]; |
| 928 | |
| 929 | for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++) |
| 930 | init_user_ns.ucount_max[i] = max_threads/2; |
| 931 | |
| 932 | set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY); |
| 933 | set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY); |
| 934 | set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY); |
| 935 | set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY); |
| 936 | |
| 937 | #ifdef CONFIG_VMAP_STACK |
| 938 | cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache", |
| 939 | NULL, free_vm_stack_cache); |
| 940 | #endif |
| 941 | |
| 942 | scs_init(); |
| 943 | |
| 944 | lockdep_init_task(&init_task); |
| 945 | uprobes_init(); |
| 946 | } |
| 947 | |
| 948 | int __weak arch_dup_task_struct(struct task_struct *dst, |
| 949 | struct task_struct *src) |
| 950 | { |
| 951 | *dst = *src; |
| 952 | return 0; |
| 953 | } |
| 954 | |
| 955 | void set_task_stack_end_magic(struct task_struct *tsk) |
| 956 | { |
| 957 | unsigned long *stackend; |
| 958 | |
| 959 | stackend = end_of_stack(tsk); |
| 960 | *stackend = STACK_END_MAGIC; /* for overflow detection */ |
| 961 | } |
| 962 | |
| 963 | static struct task_struct *dup_task_struct(struct task_struct *orig, int node) |
| 964 | { |
| 965 | struct task_struct *tsk; |
| 966 | int err; |
| 967 | |
| 968 | if (node == NUMA_NO_NODE) |
| 969 | node = tsk_fork_get_node(orig); |
| 970 | tsk = alloc_task_struct_node(node); |
| 971 | if (!tsk) |
| 972 | return NULL; |
| 973 | |
| 974 | err = arch_dup_task_struct(tsk, orig); |
| 975 | if (err) |
| 976 | goto free_tsk; |
| 977 | |
| 978 | err = alloc_thread_stack_node(tsk, node); |
| 979 | if (err) |
| 980 | goto free_tsk; |
| 981 | |
| 982 | #ifdef CONFIG_THREAD_INFO_IN_TASK |
| 983 | refcount_set(&tsk->stack_refcount, 1); |
| 984 | #endif |
| 985 | account_kernel_stack(tsk, 1); |
| 986 | |
| 987 | err = scs_prepare(tsk, node); |
| 988 | if (err) |
| 989 | goto free_stack; |
| 990 | |
| 991 | #ifdef CONFIG_SECCOMP |
| 992 | /* |
| 993 | * We must handle setting up seccomp filters once we're under |
| 994 | * the sighand lock in case orig has changed between now and |
| 995 | * then. Until then, filter must be NULL to avoid messing up |
| 996 | * the usage counts on the error path calling free_task. |
| 997 | */ |
| 998 | tsk->seccomp.filter = NULL; |
| 999 | #endif |
| 1000 | |
| 1001 | setup_thread_stack(tsk, orig); |
| 1002 | clear_user_return_notifier(tsk); |
| 1003 | clear_tsk_need_resched(tsk); |
| 1004 | set_task_stack_end_magic(tsk); |
| 1005 | clear_syscall_work_syscall_user_dispatch(tsk); |
| 1006 | |
| 1007 | #ifdef CONFIG_STACKPROTECTOR |
| 1008 | tsk->stack_canary = get_random_canary(); |
| 1009 | #endif |
| 1010 | if (orig->cpus_ptr == &orig->cpus_mask) |
| 1011 | tsk->cpus_ptr = &tsk->cpus_mask; |
| 1012 | dup_user_cpus_ptr(tsk, orig, node); |
| 1013 | |
| 1014 | /* |
| 1015 | * One for the user space visible state that goes away when reaped. |
| 1016 | * One for the scheduler. |
| 1017 | */ |
| 1018 | refcount_set(&tsk->rcu_users, 2); |
| 1019 | /* One for the rcu users */ |
| 1020 | refcount_set(&tsk->usage, 1); |
| 1021 | #ifdef CONFIG_BLK_DEV_IO_TRACE |
| 1022 | tsk->btrace_seq = 0; |
| 1023 | #endif |
| 1024 | tsk->splice_pipe = NULL; |
| 1025 | tsk->task_frag.page = NULL; |
| 1026 | tsk->wake_q.next = NULL; |
| 1027 | tsk->worker_private = NULL; |
| 1028 | |
| 1029 | kcov_task_init(tsk); |
| 1030 | kmap_local_fork(tsk); |
| 1031 | |
| 1032 | #ifdef CONFIG_FAULT_INJECTION |
| 1033 | tsk->fail_nth = 0; |
| 1034 | #endif |
| 1035 | |
| 1036 | #ifdef CONFIG_BLK_CGROUP |
| 1037 | tsk->throttle_queue = NULL; |
| 1038 | tsk->use_memdelay = 0; |
| 1039 | #endif |
| 1040 | |
| 1041 | #ifdef CONFIG_IOMMU_SVA |
| 1042 | tsk->pasid_activated = 0; |
| 1043 | #endif |
| 1044 | |
| 1045 | #ifdef CONFIG_MEMCG |
| 1046 | tsk->active_memcg = NULL; |
| 1047 | #endif |
| 1048 | return tsk; |
| 1049 | |
| 1050 | free_stack: |
| 1051 | exit_task_stack_account(tsk); |
| 1052 | free_thread_stack(tsk); |
| 1053 | free_tsk: |
| 1054 | free_task_struct(tsk); |
| 1055 | return NULL; |
| 1056 | } |
| 1057 | |
| 1058 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); |
| 1059 | |
| 1060 | static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; |
| 1061 | |
| 1062 | static int __init coredump_filter_setup(char *s) |
| 1063 | { |
| 1064 | default_dump_filter = |
| 1065 | (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & |
| 1066 | MMF_DUMP_FILTER_MASK; |
| 1067 | return 1; |
| 1068 | } |
| 1069 | |
| 1070 | __setup("coredump_filter=", coredump_filter_setup); |
| 1071 | |
| 1072 | #include <linux/init_task.h> |
| 1073 | |
| 1074 | static void mm_init_aio(struct mm_struct *mm) |
| 1075 | { |
| 1076 | #ifdef CONFIG_AIO |
| 1077 | spin_lock_init(&mm->ioctx_lock); |
| 1078 | mm->ioctx_table = NULL; |
| 1079 | #endif |
| 1080 | } |
| 1081 | |
| 1082 | static __always_inline void mm_clear_owner(struct mm_struct *mm, |
| 1083 | struct task_struct *p) |
| 1084 | { |
| 1085 | #ifdef CONFIG_MEMCG |
| 1086 | if (mm->owner == p) |
| 1087 | WRITE_ONCE(mm->owner, NULL); |
| 1088 | #endif |
| 1089 | } |
| 1090 | |
| 1091 | static void mm_init_owner(struct mm_struct *mm, struct task_struct *p) |
| 1092 | { |
| 1093 | #ifdef CONFIG_MEMCG |
| 1094 | mm->owner = p; |
| 1095 | #endif |
| 1096 | } |
| 1097 | |
| 1098 | static void mm_init_uprobes_state(struct mm_struct *mm) |
| 1099 | { |
| 1100 | #ifdef CONFIG_UPROBES |
| 1101 | mm->uprobes_state.xol_area = NULL; |
| 1102 | #endif |
| 1103 | } |
| 1104 | |
| 1105 | static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, |
| 1106 | struct user_namespace *user_ns) |
| 1107 | { |
| 1108 | mm->mmap = NULL; |
| 1109 | mm->mm_rb = RB_ROOT; |
| 1110 | mm->vmacache_seqnum = 0; |
| 1111 | atomic_set(&mm->mm_users, 1); |
| 1112 | atomic_set(&mm->mm_count, 1); |
| 1113 | seqcount_init(&mm->write_protect_seq); |
| 1114 | mmap_init_lock(mm); |
| 1115 | INIT_LIST_HEAD(&mm->mmlist); |
| 1116 | mm_pgtables_bytes_init(mm); |
| 1117 | mm->map_count = 0; |
| 1118 | mm->locked_vm = 0; |
| 1119 | atomic64_set(&mm->pinned_vm, 0); |
| 1120 | memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); |
| 1121 | spin_lock_init(&mm->page_table_lock); |
| 1122 | spin_lock_init(&mm->arg_lock); |
| 1123 | mm_init_cpumask(mm); |
| 1124 | mm_init_aio(mm); |
| 1125 | mm_init_owner(mm, p); |
| 1126 | mm_pasid_init(mm); |
| 1127 | RCU_INIT_POINTER(mm->exe_file, NULL); |
| 1128 | mmu_notifier_subscriptions_init(mm); |
| 1129 | init_tlb_flush_pending(mm); |
| 1130 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS |
| 1131 | mm->pmd_huge_pte = NULL; |
| 1132 | #endif |
| 1133 | mm_init_uprobes_state(mm); |
| 1134 | hugetlb_count_init(mm); |
| 1135 | |
| 1136 | if (current->mm) { |
| 1137 | mm->flags = current->mm->flags & MMF_INIT_MASK; |
| 1138 | mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK; |
| 1139 | } else { |
| 1140 | mm->flags = default_dump_filter; |
| 1141 | mm->def_flags = 0; |
| 1142 | } |
| 1143 | |
| 1144 | if (mm_alloc_pgd(mm)) |
| 1145 | goto fail_nopgd; |
| 1146 | |
| 1147 | if (init_new_context(p, mm)) |
| 1148 | goto fail_nocontext; |
| 1149 | |
| 1150 | mm->user_ns = get_user_ns(user_ns); |
| 1151 | return mm; |
| 1152 | |
| 1153 | fail_nocontext: |
| 1154 | mm_free_pgd(mm); |
| 1155 | fail_nopgd: |
| 1156 | free_mm(mm); |
| 1157 | return NULL; |
| 1158 | } |
| 1159 | |
| 1160 | /* |
| 1161 | * Allocate and initialize an mm_struct. |
| 1162 | */ |
| 1163 | struct mm_struct *mm_alloc(void) |
| 1164 | { |
| 1165 | struct mm_struct *mm; |
| 1166 | |
| 1167 | mm = allocate_mm(); |
| 1168 | if (!mm) |
| 1169 | return NULL; |
| 1170 | |
| 1171 | memset(mm, 0, sizeof(*mm)); |
| 1172 | return mm_init(mm, current, current_user_ns()); |
| 1173 | } |
| 1174 | |
| 1175 | static inline void __mmput(struct mm_struct *mm) |
| 1176 | { |
| 1177 | VM_BUG_ON(atomic_read(&mm->mm_users)); |
| 1178 | |
| 1179 | uprobe_clear_state(mm); |
| 1180 | exit_aio(mm); |
| 1181 | ksm_exit(mm); |
| 1182 | khugepaged_exit(mm); /* must run before exit_mmap */ |
| 1183 | exit_mmap(mm); |
| 1184 | mm_put_huge_zero_page(mm); |
| 1185 | set_mm_exe_file(mm, NULL); |
| 1186 | if (!list_empty(&mm->mmlist)) { |
| 1187 | spin_lock(&mmlist_lock); |
| 1188 | list_del(&mm->mmlist); |
| 1189 | spin_unlock(&mmlist_lock); |
| 1190 | } |
| 1191 | if (mm->binfmt) |
| 1192 | module_put(mm->binfmt->module); |
| 1193 | mm_pasid_drop(mm); |
| 1194 | mmdrop(mm); |
| 1195 | } |
| 1196 | |
| 1197 | /* |
| 1198 | * Decrement the use count and release all resources for an mm. |
| 1199 | */ |
| 1200 | void mmput(struct mm_struct *mm) |
| 1201 | { |
| 1202 | might_sleep(); |
| 1203 | |
| 1204 | if (atomic_dec_and_test(&mm->mm_users)) |
| 1205 | __mmput(mm); |
| 1206 | } |
| 1207 | EXPORT_SYMBOL_GPL(mmput); |
| 1208 | |
| 1209 | #ifdef CONFIG_MMU |
| 1210 | static void mmput_async_fn(struct work_struct *work) |
| 1211 | { |
| 1212 | struct mm_struct *mm = container_of(work, struct mm_struct, |
| 1213 | async_put_work); |
| 1214 | |
| 1215 | __mmput(mm); |
| 1216 | } |
| 1217 | |
| 1218 | void mmput_async(struct mm_struct *mm) |
| 1219 | { |
| 1220 | if (atomic_dec_and_test(&mm->mm_users)) { |
| 1221 | INIT_WORK(&mm->async_put_work, mmput_async_fn); |
| 1222 | schedule_work(&mm->async_put_work); |
| 1223 | } |
| 1224 | } |
| 1225 | #endif |
| 1226 | |
| 1227 | /** |
| 1228 | * set_mm_exe_file - change a reference to the mm's executable file |
| 1229 | * |
| 1230 | * This changes mm's executable file (shown as symlink /proc/[pid]/exe). |
| 1231 | * |
| 1232 | * Main users are mmput() and sys_execve(). Callers prevent concurrent |
| 1233 | * invocations: in mmput() nobody alive left, in execve task is single |
| 1234 | * threaded. |
| 1235 | * |
| 1236 | * Can only fail if new_exe_file != NULL. |
| 1237 | */ |
| 1238 | int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) |
| 1239 | { |
| 1240 | struct file *old_exe_file; |
| 1241 | |
| 1242 | /* |
| 1243 | * It is safe to dereference the exe_file without RCU as |
| 1244 | * this function is only called if nobody else can access |
| 1245 | * this mm -- see comment above for justification. |
| 1246 | */ |
| 1247 | old_exe_file = rcu_dereference_raw(mm->exe_file); |
| 1248 | |
| 1249 | if (new_exe_file) { |
| 1250 | /* |
| 1251 | * We expect the caller (i.e., sys_execve) to already denied |
| 1252 | * write access, so this is unlikely to fail. |
| 1253 | */ |
| 1254 | if (unlikely(deny_write_access(new_exe_file))) |
| 1255 | return -EACCES; |
| 1256 | get_file(new_exe_file); |
| 1257 | } |
| 1258 | rcu_assign_pointer(mm->exe_file, new_exe_file); |
| 1259 | if (old_exe_file) { |
| 1260 | allow_write_access(old_exe_file); |
| 1261 | fput(old_exe_file); |
| 1262 | } |
| 1263 | return 0; |
| 1264 | } |
| 1265 | |
| 1266 | /** |
| 1267 | * replace_mm_exe_file - replace a reference to the mm's executable file |
| 1268 | * |
| 1269 | * This changes mm's executable file (shown as symlink /proc/[pid]/exe), |
| 1270 | * dealing with concurrent invocation and without grabbing the mmap lock in |
| 1271 | * write mode. |
| 1272 | * |
| 1273 | * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE). |
| 1274 | */ |
| 1275 | int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) |
| 1276 | { |
| 1277 | struct vm_area_struct *vma; |
| 1278 | struct file *old_exe_file; |
| 1279 | int ret = 0; |
| 1280 | |
| 1281 | /* Forbid mm->exe_file change if old file still mapped. */ |
| 1282 | old_exe_file = get_mm_exe_file(mm); |
| 1283 | if (old_exe_file) { |
| 1284 | mmap_read_lock(mm); |
| 1285 | for (vma = mm->mmap; vma && !ret; vma = vma->vm_next) { |
| 1286 | if (!vma->vm_file) |
| 1287 | continue; |
| 1288 | if (path_equal(&vma->vm_file->f_path, |
| 1289 | &old_exe_file->f_path)) |
| 1290 | ret = -EBUSY; |
| 1291 | } |
| 1292 | mmap_read_unlock(mm); |
| 1293 | fput(old_exe_file); |
| 1294 | if (ret) |
| 1295 | return ret; |
| 1296 | } |
| 1297 | |
| 1298 | /* set the new file, lockless */ |
| 1299 | ret = deny_write_access(new_exe_file); |
| 1300 | if (ret) |
| 1301 | return -EACCES; |
| 1302 | get_file(new_exe_file); |
| 1303 | |
| 1304 | old_exe_file = xchg(&mm->exe_file, new_exe_file); |
| 1305 | if (old_exe_file) { |
| 1306 | /* |
| 1307 | * Don't race with dup_mmap() getting the file and disallowing |
| 1308 | * write access while someone might open the file writable. |
| 1309 | */ |
| 1310 | mmap_read_lock(mm); |
| 1311 | allow_write_access(old_exe_file); |
| 1312 | fput(old_exe_file); |
| 1313 | mmap_read_unlock(mm); |
| 1314 | } |
| 1315 | return 0; |
| 1316 | } |
| 1317 | |
| 1318 | /** |
| 1319 | * get_mm_exe_file - acquire a reference to the mm's executable file |
| 1320 | * |
| 1321 | * Returns %NULL if mm has no associated executable file. |
| 1322 | * User must release file via fput(). |
| 1323 | */ |
| 1324 | struct file *get_mm_exe_file(struct mm_struct *mm) |
| 1325 | { |
| 1326 | struct file *exe_file; |
| 1327 | |
| 1328 | rcu_read_lock(); |
| 1329 | exe_file = rcu_dereference(mm->exe_file); |
| 1330 | if (exe_file && !get_file_rcu(exe_file)) |
| 1331 | exe_file = NULL; |
| 1332 | rcu_read_unlock(); |
| 1333 | return exe_file; |
| 1334 | } |
| 1335 | |
| 1336 | /** |
| 1337 | * get_task_exe_file - acquire a reference to the task's executable file |
| 1338 | * |
| 1339 | * Returns %NULL if task's mm (if any) has no associated executable file or |
| 1340 | * this is a kernel thread with borrowed mm (see the comment above get_task_mm). |
| 1341 | * User must release file via fput(). |
| 1342 | */ |
| 1343 | struct file *get_task_exe_file(struct task_struct *task) |
| 1344 | { |
| 1345 | struct file *exe_file = NULL; |
| 1346 | struct mm_struct *mm; |
| 1347 | |
| 1348 | task_lock(task); |
| 1349 | mm = task->mm; |
| 1350 | if (mm) { |
| 1351 | if (!(task->flags & PF_KTHREAD)) |
| 1352 | exe_file = get_mm_exe_file(mm); |
| 1353 | } |
| 1354 | task_unlock(task); |
| 1355 | return exe_file; |
| 1356 | } |
| 1357 | |
| 1358 | /** |
| 1359 | * get_task_mm - acquire a reference to the task's mm |
| 1360 | * |
| 1361 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning |
| 1362 | * this kernel workthread has transiently adopted a user mm with use_mm, |
| 1363 | * to do its AIO) is not set and if so returns a reference to it, after |
| 1364 | * bumping up the use count. User must release the mm via mmput() |
| 1365 | * after use. Typically used by /proc and ptrace. |
| 1366 | */ |
| 1367 | struct mm_struct *get_task_mm(struct task_struct *task) |
| 1368 | { |
| 1369 | struct mm_struct *mm; |
| 1370 | |
| 1371 | task_lock(task); |
| 1372 | mm = task->mm; |
| 1373 | if (mm) { |
| 1374 | if (task->flags & PF_KTHREAD) |
| 1375 | mm = NULL; |
| 1376 | else |
| 1377 | mmget(mm); |
| 1378 | } |
| 1379 | task_unlock(task); |
| 1380 | return mm; |
| 1381 | } |
| 1382 | EXPORT_SYMBOL_GPL(get_task_mm); |
| 1383 | |
| 1384 | struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) |
| 1385 | { |
| 1386 | struct mm_struct *mm; |
| 1387 | int err; |
| 1388 | |
| 1389 | err = down_read_killable(&task->signal->exec_update_lock); |
| 1390 | if (err) |
| 1391 | return ERR_PTR(err); |
| 1392 | |
| 1393 | mm = get_task_mm(task); |
| 1394 | if (mm && mm != current->mm && |
| 1395 | !ptrace_may_access(task, mode)) { |
| 1396 | mmput(mm); |
| 1397 | mm = ERR_PTR(-EACCES); |
| 1398 | } |
| 1399 | up_read(&task->signal->exec_update_lock); |
| 1400 | |
| 1401 | return mm; |
| 1402 | } |
| 1403 | |
| 1404 | static void complete_vfork_done(struct task_struct *tsk) |
| 1405 | { |
| 1406 | struct completion *vfork; |
| 1407 | |
| 1408 | task_lock(tsk); |
| 1409 | vfork = tsk->vfork_done; |
| 1410 | if (likely(vfork)) { |
| 1411 | tsk->vfork_done = NULL; |
| 1412 | complete(vfork); |
| 1413 | } |
| 1414 | task_unlock(tsk); |
| 1415 | } |
| 1416 | |
| 1417 | static int wait_for_vfork_done(struct task_struct *child, |
| 1418 | struct completion *vfork) |
| 1419 | { |
| 1420 | int killed; |
| 1421 | |
| 1422 | freezer_do_not_count(); |
| 1423 | cgroup_enter_frozen(); |
| 1424 | killed = wait_for_completion_killable(vfork); |
| 1425 | cgroup_leave_frozen(false); |
| 1426 | freezer_count(); |
| 1427 | |
| 1428 | if (killed) { |
| 1429 | task_lock(child); |
| 1430 | child->vfork_done = NULL; |
| 1431 | task_unlock(child); |
| 1432 | } |
| 1433 | |
| 1434 | put_task_struct(child); |
| 1435 | return killed; |
| 1436 | } |
| 1437 | |
| 1438 | /* Please note the differences between mmput and mm_release. |
| 1439 | * mmput is called whenever we stop holding onto a mm_struct, |
| 1440 | * error success whatever. |
| 1441 | * |
| 1442 | * mm_release is called after a mm_struct has been removed |
| 1443 | * from the current process. |
| 1444 | * |
| 1445 | * This difference is important for error handling, when we |
| 1446 | * only half set up a mm_struct for a new process and need to restore |
| 1447 | * the old one. Because we mmput the new mm_struct before |
| 1448 | * restoring the old one. . . |
| 1449 | * Eric Biederman 10 January 1998 |
| 1450 | */ |
| 1451 | static void mm_release(struct task_struct *tsk, struct mm_struct *mm) |
| 1452 | { |
| 1453 | uprobe_free_utask(tsk); |
| 1454 | |
| 1455 | /* Get rid of any cached register state */ |
| 1456 | deactivate_mm(tsk, mm); |
| 1457 | |
| 1458 | /* |
| 1459 | * Signal userspace if we're not exiting with a core dump |
| 1460 | * because we want to leave the value intact for debugging |
| 1461 | * purposes. |
| 1462 | */ |
| 1463 | if (tsk->clear_child_tid) { |
| 1464 | if (atomic_read(&mm->mm_users) > 1) { |
| 1465 | /* |
| 1466 | * We don't check the error code - if userspace has |
| 1467 | * not set up a proper pointer then tough luck. |
| 1468 | */ |
| 1469 | put_user(0, tsk->clear_child_tid); |
| 1470 | do_futex(tsk->clear_child_tid, FUTEX_WAKE, |
| 1471 | 1, NULL, NULL, 0, 0); |
| 1472 | } |
| 1473 | tsk->clear_child_tid = NULL; |
| 1474 | } |
| 1475 | |
| 1476 | /* |
| 1477 | * All done, finally we can wake up parent and return this mm to him. |
| 1478 | * Also kthread_stop() uses this completion for synchronization. |
| 1479 | */ |
| 1480 | if (tsk->vfork_done) |
| 1481 | complete_vfork_done(tsk); |
| 1482 | } |
| 1483 | |
| 1484 | void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm) |
| 1485 | { |
| 1486 | futex_exit_release(tsk); |
| 1487 | mm_release(tsk, mm); |
| 1488 | } |
| 1489 | |
| 1490 | void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm) |
| 1491 | { |
| 1492 | futex_exec_release(tsk); |
| 1493 | mm_release(tsk, mm); |
| 1494 | } |
| 1495 | |
| 1496 | /** |
| 1497 | * dup_mm() - duplicates an existing mm structure |
| 1498 | * @tsk: the task_struct with which the new mm will be associated. |
| 1499 | * @oldmm: the mm to duplicate. |
| 1500 | * |
| 1501 | * Allocates a new mm structure and duplicates the provided @oldmm structure |
| 1502 | * content into it. |
| 1503 | * |
| 1504 | * Return: the duplicated mm or NULL on failure. |
| 1505 | */ |
| 1506 | static struct mm_struct *dup_mm(struct task_struct *tsk, |
| 1507 | struct mm_struct *oldmm) |
| 1508 | { |
| 1509 | struct mm_struct *mm; |
| 1510 | int err; |
| 1511 | |
| 1512 | mm = allocate_mm(); |
| 1513 | if (!mm) |
| 1514 | goto fail_nomem; |
| 1515 | |
| 1516 | memcpy(mm, oldmm, sizeof(*mm)); |
| 1517 | |
| 1518 | if (!mm_init(mm, tsk, mm->user_ns)) |
| 1519 | goto fail_nomem; |
| 1520 | |
| 1521 | err = dup_mmap(mm, oldmm); |
| 1522 | if (err) |
| 1523 | goto free_pt; |
| 1524 | |
| 1525 | mm->hiwater_rss = get_mm_rss(mm); |
| 1526 | mm->hiwater_vm = mm->total_vm; |
| 1527 | |
| 1528 | if (mm->binfmt && !try_module_get(mm->binfmt->module)) |
| 1529 | goto free_pt; |
| 1530 | |
| 1531 | return mm; |
| 1532 | |
| 1533 | free_pt: |
| 1534 | /* don't put binfmt in mmput, we haven't got module yet */ |
| 1535 | mm->binfmt = NULL; |
| 1536 | mm_init_owner(mm, NULL); |
| 1537 | mmput(mm); |
| 1538 | |
| 1539 | fail_nomem: |
| 1540 | return NULL; |
| 1541 | } |
| 1542 | |
| 1543 | static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) |
| 1544 | { |
| 1545 | struct mm_struct *mm, *oldmm; |
| 1546 | |
| 1547 | tsk->min_flt = tsk->maj_flt = 0; |
| 1548 | tsk->nvcsw = tsk->nivcsw = 0; |
| 1549 | #ifdef CONFIG_DETECT_HUNG_TASK |
| 1550 | tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; |
| 1551 | tsk->last_switch_time = 0; |
| 1552 | #endif |
| 1553 | |
| 1554 | tsk->mm = NULL; |
| 1555 | tsk->active_mm = NULL; |
| 1556 | |
| 1557 | /* |
| 1558 | * Are we cloning a kernel thread? |
| 1559 | * |
| 1560 | * We need to steal a active VM for that.. |
| 1561 | */ |
| 1562 | oldmm = current->mm; |
| 1563 | if (!oldmm) |
| 1564 | return 0; |
| 1565 | |
| 1566 | /* initialize the new vmacache entries */ |
| 1567 | vmacache_flush(tsk); |
| 1568 | |
| 1569 | if (clone_flags & CLONE_VM) { |
| 1570 | mmget(oldmm); |
| 1571 | mm = oldmm; |
| 1572 | } else { |
| 1573 | mm = dup_mm(tsk, current->mm); |
| 1574 | if (!mm) |
| 1575 | return -ENOMEM; |
| 1576 | } |
| 1577 | |
| 1578 | tsk->mm = mm; |
| 1579 | tsk->active_mm = mm; |
| 1580 | return 0; |
| 1581 | } |
| 1582 | |
| 1583 | static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) |
| 1584 | { |
| 1585 | struct fs_struct *fs = current->fs; |
| 1586 | if (clone_flags & CLONE_FS) { |
| 1587 | /* tsk->fs is already what we want */ |
| 1588 | spin_lock(&fs->lock); |
| 1589 | if (fs->in_exec) { |
| 1590 | spin_unlock(&fs->lock); |
| 1591 | return -EAGAIN; |
| 1592 | } |
| 1593 | fs->users++; |
| 1594 | spin_unlock(&fs->lock); |
| 1595 | return 0; |
| 1596 | } |
| 1597 | tsk->fs = copy_fs_struct(fs); |
| 1598 | if (!tsk->fs) |
| 1599 | return -ENOMEM; |
| 1600 | return 0; |
| 1601 | } |
| 1602 | |
| 1603 | static int copy_files(unsigned long clone_flags, struct task_struct *tsk) |
| 1604 | { |
| 1605 | struct files_struct *oldf, *newf; |
| 1606 | int error = 0; |
| 1607 | |
| 1608 | /* |
| 1609 | * A background process may not have any files ... |
| 1610 | */ |
| 1611 | oldf = current->files; |
| 1612 | if (!oldf) |
| 1613 | goto out; |
| 1614 | |
| 1615 | if (clone_flags & CLONE_FILES) { |
| 1616 | atomic_inc(&oldf->count); |
| 1617 | goto out; |
| 1618 | } |
| 1619 | |
| 1620 | newf = dup_fd(oldf, NR_OPEN_MAX, &error); |
| 1621 | if (!newf) |
| 1622 | goto out; |
| 1623 | |
| 1624 | tsk->files = newf; |
| 1625 | error = 0; |
| 1626 | out: |
| 1627 | return error; |
| 1628 | } |
| 1629 | |
| 1630 | static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) |
| 1631 | { |
| 1632 | struct sighand_struct *sig; |
| 1633 | |
| 1634 | if (clone_flags & CLONE_SIGHAND) { |
| 1635 | refcount_inc(¤t->sighand->count); |
| 1636 | return 0; |
| 1637 | } |
| 1638 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
| 1639 | RCU_INIT_POINTER(tsk->sighand, sig); |
| 1640 | if (!sig) |
| 1641 | return -ENOMEM; |
| 1642 | |
| 1643 | refcount_set(&sig->count, 1); |
| 1644 | spin_lock_irq(¤t->sighand->siglock); |
| 1645 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); |
| 1646 | spin_unlock_irq(¤t->sighand->siglock); |
| 1647 | |
| 1648 | /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */ |
| 1649 | if (clone_flags & CLONE_CLEAR_SIGHAND) |
| 1650 | flush_signal_handlers(tsk, 0); |
| 1651 | |
| 1652 | return 0; |
| 1653 | } |
| 1654 | |
| 1655 | void __cleanup_sighand(struct sighand_struct *sighand) |
| 1656 | { |
| 1657 | if (refcount_dec_and_test(&sighand->count)) { |
| 1658 | signalfd_cleanup(sighand); |
| 1659 | /* |
| 1660 | * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it |
| 1661 | * without an RCU grace period, see __lock_task_sighand(). |
| 1662 | */ |
| 1663 | kmem_cache_free(sighand_cachep, sighand); |
| 1664 | } |
| 1665 | } |
| 1666 | |
| 1667 | /* |
| 1668 | * Initialize POSIX timer handling for a thread group. |
| 1669 | */ |
| 1670 | static void posix_cpu_timers_init_group(struct signal_struct *sig) |
| 1671 | { |
| 1672 | struct posix_cputimers *pct = &sig->posix_cputimers; |
| 1673 | unsigned long cpu_limit; |
| 1674 | |
| 1675 | cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); |
| 1676 | posix_cputimers_group_init(pct, cpu_limit); |
| 1677 | } |
| 1678 | |
| 1679 | static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) |
| 1680 | { |
| 1681 | struct signal_struct *sig; |
| 1682 | |
| 1683 | if (clone_flags & CLONE_THREAD) |
| 1684 | return 0; |
| 1685 | |
| 1686 | sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); |
| 1687 | tsk->signal = sig; |
| 1688 | if (!sig) |
| 1689 | return -ENOMEM; |
| 1690 | |
| 1691 | sig->nr_threads = 1; |
| 1692 | atomic_set(&sig->live, 1); |
| 1693 | refcount_set(&sig->sigcnt, 1); |
| 1694 | |
| 1695 | /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ |
| 1696 | sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); |
| 1697 | tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head); |
| 1698 | |
| 1699 | init_waitqueue_head(&sig->wait_chldexit); |
| 1700 | sig->curr_target = tsk; |
| 1701 | init_sigpending(&sig->shared_pending); |
| 1702 | INIT_HLIST_HEAD(&sig->multiprocess); |
| 1703 | seqlock_init(&sig->stats_lock); |
| 1704 | prev_cputime_init(&sig->prev_cputime); |
| 1705 | |
| 1706 | #ifdef CONFIG_POSIX_TIMERS |
| 1707 | INIT_LIST_HEAD(&sig->posix_timers); |
| 1708 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| 1709 | sig->real_timer.function = it_real_fn; |
| 1710 | #endif |
| 1711 | |
| 1712 | task_lock(current->group_leader); |
| 1713 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); |
| 1714 | task_unlock(current->group_leader); |
| 1715 | |
| 1716 | posix_cpu_timers_init_group(sig); |
| 1717 | |
| 1718 | tty_audit_fork(sig); |
| 1719 | sched_autogroup_fork(sig); |
| 1720 | |
| 1721 | sig->oom_score_adj = current->signal->oom_score_adj; |
| 1722 | sig->oom_score_adj_min = current->signal->oom_score_adj_min; |
| 1723 | |
| 1724 | mutex_init(&sig->cred_guard_mutex); |
| 1725 | init_rwsem(&sig->exec_update_lock); |
| 1726 | |
| 1727 | return 0; |
| 1728 | } |
| 1729 | |
| 1730 | static void copy_seccomp(struct task_struct *p) |
| 1731 | { |
| 1732 | #ifdef CONFIG_SECCOMP |
| 1733 | /* |
| 1734 | * Must be called with sighand->lock held, which is common to |
| 1735 | * all threads in the group. Holding cred_guard_mutex is not |
| 1736 | * needed because this new task is not yet running and cannot |
| 1737 | * be racing exec. |
| 1738 | */ |
| 1739 | assert_spin_locked(¤t->sighand->siglock); |
| 1740 | |
| 1741 | /* Ref-count the new filter user, and assign it. */ |
| 1742 | get_seccomp_filter(current); |
| 1743 | p->seccomp = current->seccomp; |
| 1744 | |
| 1745 | /* |
| 1746 | * Explicitly enable no_new_privs here in case it got set |
| 1747 | * between the task_struct being duplicated and holding the |
| 1748 | * sighand lock. The seccomp state and nnp must be in sync. |
| 1749 | */ |
| 1750 | if (task_no_new_privs(current)) |
| 1751 | task_set_no_new_privs(p); |
| 1752 | |
| 1753 | /* |
| 1754 | * If the parent gained a seccomp mode after copying thread |
| 1755 | * flags and between before we held the sighand lock, we have |
| 1756 | * to manually enable the seccomp thread flag here. |
| 1757 | */ |
| 1758 | if (p->seccomp.mode != SECCOMP_MODE_DISABLED) |
| 1759 | set_task_syscall_work(p, SECCOMP); |
| 1760 | #endif |
| 1761 | } |
| 1762 | |
| 1763 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) |
| 1764 | { |
| 1765 | current->clear_child_tid = tidptr; |
| 1766 | |
| 1767 | return task_pid_vnr(current); |
| 1768 | } |
| 1769 | |
| 1770 | static void rt_mutex_init_task(struct task_struct *p) |
| 1771 | { |
| 1772 | raw_spin_lock_init(&p->pi_lock); |
| 1773 | #ifdef CONFIG_RT_MUTEXES |
| 1774 | p->pi_waiters = RB_ROOT_CACHED; |
| 1775 | p->pi_top_task = NULL; |
| 1776 | p->pi_blocked_on = NULL; |
| 1777 | #endif |
| 1778 | } |
| 1779 | |
| 1780 | static inline void init_task_pid_links(struct task_struct *task) |
| 1781 | { |
| 1782 | enum pid_type type; |
| 1783 | |
| 1784 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) |
| 1785 | INIT_HLIST_NODE(&task->pid_links[type]); |
| 1786 | } |
| 1787 | |
| 1788 | static inline void |
| 1789 | init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) |
| 1790 | { |
| 1791 | if (type == PIDTYPE_PID) |
| 1792 | task->thread_pid = pid; |
| 1793 | else |
| 1794 | task->signal->pids[type] = pid; |
| 1795 | } |
| 1796 | |
| 1797 | static inline void rcu_copy_process(struct task_struct *p) |
| 1798 | { |
| 1799 | #ifdef CONFIG_PREEMPT_RCU |
| 1800 | p->rcu_read_lock_nesting = 0; |
| 1801 | p->rcu_read_unlock_special.s = 0; |
| 1802 | p->rcu_blocked_node = NULL; |
| 1803 | INIT_LIST_HEAD(&p->rcu_node_entry); |
| 1804 | #endif /* #ifdef CONFIG_PREEMPT_RCU */ |
| 1805 | #ifdef CONFIG_TASKS_RCU |
| 1806 | p->rcu_tasks_holdout = false; |
| 1807 | INIT_LIST_HEAD(&p->rcu_tasks_holdout_list); |
| 1808 | p->rcu_tasks_idle_cpu = -1; |
| 1809 | #endif /* #ifdef CONFIG_TASKS_RCU */ |
| 1810 | #ifdef CONFIG_TASKS_TRACE_RCU |
| 1811 | p->trc_reader_nesting = 0; |
| 1812 | p->trc_reader_special.s = 0; |
| 1813 | INIT_LIST_HEAD(&p->trc_holdout_list); |
| 1814 | #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ |
| 1815 | } |
| 1816 | |
| 1817 | struct pid *pidfd_pid(const struct file *file) |
| 1818 | { |
| 1819 | if (file->f_op == &pidfd_fops) |
| 1820 | return file->private_data; |
| 1821 | |
| 1822 | return ERR_PTR(-EBADF); |
| 1823 | } |
| 1824 | |
| 1825 | static int pidfd_release(struct inode *inode, struct file *file) |
| 1826 | { |
| 1827 | struct pid *pid = file->private_data; |
| 1828 | |
| 1829 | file->private_data = NULL; |
| 1830 | put_pid(pid); |
| 1831 | return 0; |
| 1832 | } |
| 1833 | |
| 1834 | #ifdef CONFIG_PROC_FS |
| 1835 | /** |
| 1836 | * pidfd_show_fdinfo - print information about a pidfd |
| 1837 | * @m: proc fdinfo file |
| 1838 | * @f: file referencing a pidfd |
| 1839 | * |
| 1840 | * Pid: |
| 1841 | * This function will print the pid that a given pidfd refers to in the |
| 1842 | * pid namespace of the procfs instance. |
| 1843 | * If the pid namespace of the process is not a descendant of the pid |
| 1844 | * namespace of the procfs instance 0 will be shown as its pid. This is |
| 1845 | * similar to calling getppid() on a process whose parent is outside of |
| 1846 | * its pid namespace. |
| 1847 | * |
| 1848 | * NSpid: |
| 1849 | * If pid namespaces are supported then this function will also print |
| 1850 | * the pid of a given pidfd refers to for all descendant pid namespaces |
| 1851 | * starting from the current pid namespace of the instance, i.e. the |
| 1852 | * Pid field and the first entry in the NSpid field will be identical. |
| 1853 | * If the pid namespace of the process is not a descendant of the pid |
| 1854 | * namespace of the procfs instance 0 will be shown as its first NSpid |
| 1855 | * entry and no others will be shown. |
| 1856 | * Note that this differs from the Pid and NSpid fields in |
| 1857 | * /proc/<pid>/status where Pid and NSpid are always shown relative to |
| 1858 | * the pid namespace of the procfs instance. The difference becomes |
| 1859 | * obvious when sending around a pidfd between pid namespaces from a |
| 1860 | * different branch of the tree, i.e. where no ancestral relation is |
| 1861 | * present between the pid namespaces: |
| 1862 | * - create two new pid namespaces ns1 and ns2 in the initial pid |
| 1863 | * namespace (also take care to create new mount namespaces in the |
| 1864 | * new pid namespace and mount procfs) |
| 1865 | * - create a process with a pidfd in ns1 |
| 1866 | * - send pidfd from ns1 to ns2 |
| 1867 | * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid |
| 1868 | * have exactly one entry, which is 0 |
| 1869 | */ |
| 1870 | static void pidfd_show_fdinfo(struct seq_file *m, struct file *f) |
| 1871 | { |
| 1872 | struct pid *pid = f->private_data; |
| 1873 | struct pid_namespace *ns; |
| 1874 | pid_t nr = -1; |
| 1875 | |
| 1876 | if (likely(pid_has_task(pid, PIDTYPE_PID))) { |
| 1877 | ns = proc_pid_ns(file_inode(m->file)->i_sb); |
| 1878 | nr = pid_nr_ns(pid, ns); |
| 1879 | } |
| 1880 | |
| 1881 | seq_put_decimal_ll(m, "Pid:\t", nr); |
| 1882 | |
| 1883 | #ifdef CONFIG_PID_NS |
| 1884 | seq_put_decimal_ll(m, "\nNSpid:\t", nr); |
| 1885 | if (nr > 0) { |
| 1886 | int i; |
| 1887 | |
| 1888 | /* If nr is non-zero it means that 'pid' is valid and that |
| 1889 | * ns, i.e. the pid namespace associated with the procfs |
| 1890 | * instance, is in the pid namespace hierarchy of pid. |
| 1891 | * Start at one below the already printed level. |
| 1892 | */ |
| 1893 | for (i = ns->level + 1; i <= pid->level; i++) |
| 1894 | seq_put_decimal_ll(m, "\t", pid->numbers[i].nr); |
| 1895 | } |
| 1896 | #endif |
| 1897 | seq_putc(m, '\n'); |
| 1898 | } |
| 1899 | #endif |
| 1900 | |
| 1901 | /* |
| 1902 | * Poll support for process exit notification. |
| 1903 | */ |
| 1904 | static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts) |
| 1905 | { |
| 1906 | struct pid *pid = file->private_data; |
| 1907 | __poll_t poll_flags = 0; |
| 1908 | |
| 1909 | poll_wait(file, &pid->wait_pidfd, pts); |
| 1910 | |
| 1911 | /* |
| 1912 | * Inform pollers only when the whole thread group exits. |
| 1913 | * If the thread group leader exits before all other threads in the |
| 1914 | * group, then poll(2) should block, similar to the wait(2) family. |
| 1915 | */ |
| 1916 | if (thread_group_exited(pid)) |
| 1917 | poll_flags = EPOLLIN | EPOLLRDNORM; |
| 1918 | |
| 1919 | return poll_flags; |
| 1920 | } |
| 1921 | |
| 1922 | const struct file_operations pidfd_fops = { |
| 1923 | .release = pidfd_release, |
| 1924 | .poll = pidfd_poll, |
| 1925 | #ifdef CONFIG_PROC_FS |
| 1926 | .show_fdinfo = pidfd_show_fdinfo, |
| 1927 | #endif |
| 1928 | }; |
| 1929 | |
| 1930 | static void __delayed_free_task(struct rcu_head *rhp) |
| 1931 | { |
| 1932 | struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); |
| 1933 | |
| 1934 | free_task(tsk); |
| 1935 | } |
| 1936 | |
| 1937 | static __always_inline void delayed_free_task(struct task_struct *tsk) |
| 1938 | { |
| 1939 | if (IS_ENABLED(CONFIG_MEMCG)) |
| 1940 | call_rcu(&tsk->rcu, __delayed_free_task); |
| 1941 | else |
| 1942 | free_task(tsk); |
| 1943 | } |
| 1944 | |
| 1945 | static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk) |
| 1946 | { |
| 1947 | /* Skip if kernel thread */ |
| 1948 | if (!tsk->mm) |
| 1949 | return; |
| 1950 | |
| 1951 | /* Skip if spawning a thread or using vfork */ |
| 1952 | if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM) |
| 1953 | return; |
| 1954 | |
| 1955 | /* We need to synchronize with __set_oom_adj */ |
| 1956 | mutex_lock(&oom_adj_mutex); |
| 1957 | set_bit(MMF_MULTIPROCESS, &tsk->mm->flags); |
| 1958 | /* Update the values in case they were changed after copy_signal */ |
| 1959 | tsk->signal->oom_score_adj = current->signal->oom_score_adj; |
| 1960 | tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min; |
| 1961 | mutex_unlock(&oom_adj_mutex); |
| 1962 | } |
| 1963 | |
| 1964 | /* |
| 1965 | * This creates a new process as a copy of the old one, |
| 1966 | * but does not actually start it yet. |
| 1967 | * |
| 1968 | * It copies the registers, and all the appropriate |
| 1969 | * parts of the process environment (as per the clone |
| 1970 | * flags). The actual kick-off is left to the caller. |
| 1971 | */ |
| 1972 | static __latent_entropy struct task_struct *copy_process( |
| 1973 | struct pid *pid, |
| 1974 | int trace, |
| 1975 | int node, |
| 1976 | struct kernel_clone_args *args) |
| 1977 | { |
| 1978 | int pidfd = -1, retval; |
| 1979 | struct task_struct *p; |
| 1980 | struct multiprocess_signals delayed; |
| 1981 | struct file *pidfile = NULL; |
| 1982 | u64 clone_flags = args->flags; |
| 1983 | struct nsproxy *nsp = current->nsproxy; |
| 1984 | |
| 1985 | /* |
| 1986 | * Don't allow sharing the root directory with processes in a different |
| 1987 | * namespace |
| 1988 | */ |
| 1989 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) |
| 1990 | return ERR_PTR(-EINVAL); |
| 1991 | |
| 1992 | if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS)) |
| 1993 | return ERR_PTR(-EINVAL); |
| 1994 | |
| 1995 | /* |
| 1996 | * Thread groups must share signals as well, and detached threads |
| 1997 | * can only be started up within the thread group. |
| 1998 | */ |
| 1999 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) |
| 2000 | return ERR_PTR(-EINVAL); |
| 2001 | |
| 2002 | /* |
| 2003 | * Shared signal handlers imply shared VM. By way of the above, |
| 2004 | * thread groups also imply shared VM. Blocking this case allows |
| 2005 | * for various simplifications in other code. |
| 2006 | */ |
| 2007 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) |
| 2008 | return ERR_PTR(-EINVAL); |
| 2009 | |
| 2010 | /* |
| 2011 | * Siblings of global init remain as zombies on exit since they are |
| 2012 | * not reaped by their parent (swapper). To solve this and to avoid |
| 2013 | * multi-rooted process trees, prevent global and container-inits |
| 2014 | * from creating siblings. |
| 2015 | */ |
| 2016 | if ((clone_flags & CLONE_PARENT) && |
| 2017 | current->signal->flags & SIGNAL_UNKILLABLE) |
| 2018 | return ERR_PTR(-EINVAL); |
| 2019 | |
| 2020 | /* |
| 2021 | * If the new process will be in a different pid or user namespace |
| 2022 | * do not allow it to share a thread group with the forking task. |
| 2023 | */ |
| 2024 | if (clone_flags & CLONE_THREAD) { |
| 2025 | if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) || |
| 2026 | (task_active_pid_ns(current) != nsp->pid_ns_for_children)) |
| 2027 | return ERR_PTR(-EINVAL); |
| 2028 | } |
| 2029 | |
| 2030 | /* |
| 2031 | * If the new process will be in a different time namespace |
| 2032 | * do not allow it to share VM or a thread group with the forking task. |
| 2033 | */ |
| 2034 | if (clone_flags & (CLONE_THREAD | CLONE_VM)) { |
| 2035 | if (nsp->time_ns != nsp->time_ns_for_children) |
| 2036 | return ERR_PTR(-EINVAL); |
| 2037 | } |
| 2038 | |
| 2039 | if (clone_flags & CLONE_PIDFD) { |
| 2040 | /* |
| 2041 | * - CLONE_DETACHED is blocked so that we can potentially |
| 2042 | * reuse it later for CLONE_PIDFD. |
| 2043 | * - CLONE_THREAD is blocked until someone really needs it. |
| 2044 | */ |
| 2045 | if (clone_flags & (CLONE_DETACHED | CLONE_THREAD)) |
| 2046 | return ERR_PTR(-EINVAL); |
| 2047 | } |
| 2048 | |
| 2049 | /* |
| 2050 | * Force any signals received before this point to be delivered |
| 2051 | * before the fork happens. Collect up signals sent to multiple |
| 2052 | * processes that happen during the fork and delay them so that |
| 2053 | * they appear to happen after the fork. |
| 2054 | */ |
| 2055 | sigemptyset(&delayed.signal); |
| 2056 | INIT_HLIST_NODE(&delayed.node); |
| 2057 | |
| 2058 | spin_lock_irq(¤t->sighand->siglock); |
| 2059 | if (!(clone_flags & CLONE_THREAD)) |
| 2060 | hlist_add_head(&delayed.node, ¤t->signal->multiprocess); |
| 2061 | recalc_sigpending(); |
| 2062 | spin_unlock_irq(¤t->sighand->siglock); |
| 2063 | retval = -ERESTARTNOINTR; |
| 2064 | if (task_sigpending(current)) |
| 2065 | goto fork_out; |
| 2066 | |
| 2067 | retval = -ENOMEM; |
| 2068 | p = dup_task_struct(current, node); |
| 2069 | if (!p) |
| 2070 | goto fork_out; |
| 2071 | if (args->io_thread) { |
| 2072 | /* |
| 2073 | * Mark us an IO worker, and block any signal that isn't |
| 2074 | * fatal or STOP |
| 2075 | */ |
| 2076 | p->flags |= PF_IO_WORKER; |
| 2077 | siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
| 2078 | } |
| 2079 | |
| 2080 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL; |
| 2081 | /* |
| 2082 | * Clear TID on mm_release()? |
| 2083 | */ |
| 2084 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL; |
| 2085 | |
| 2086 | ftrace_graph_init_task(p); |
| 2087 | |
| 2088 | rt_mutex_init_task(p); |
| 2089 | |
| 2090 | lockdep_assert_irqs_enabled(); |
| 2091 | #ifdef CONFIG_PROVE_LOCKING |
| 2092 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); |
| 2093 | #endif |
| 2094 | retval = copy_creds(p, clone_flags); |
| 2095 | if (retval < 0) |
| 2096 | goto bad_fork_free; |
| 2097 | |
| 2098 | retval = -EAGAIN; |
| 2099 | if (is_ucounts_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) { |
| 2100 | if (p->real_cred->user != INIT_USER && |
| 2101 | !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) |
| 2102 | goto bad_fork_cleanup_count; |
| 2103 | } |
| 2104 | current->flags &= ~PF_NPROC_EXCEEDED; |
| 2105 | |
| 2106 | /* |
| 2107 | * If multiple threads are within copy_process(), then this check |
| 2108 | * triggers too late. This doesn't hurt, the check is only there |
| 2109 | * to stop root fork bombs. |
| 2110 | */ |
| 2111 | retval = -EAGAIN; |
| 2112 | if (data_race(nr_threads >= max_threads)) |
| 2113 | goto bad_fork_cleanup_count; |
| 2114 | |
| 2115 | delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ |
| 2116 | p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY); |
| 2117 | p->flags |= PF_FORKNOEXEC; |
| 2118 | INIT_LIST_HEAD(&p->children); |
| 2119 | INIT_LIST_HEAD(&p->sibling); |
| 2120 | rcu_copy_process(p); |
| 2121 | p->vfork_done = NULL; |
| 2122 | spin_lock_init(&p->alloc_lock); |
| 2123 | |
| 2124 | init_sigpending(&p->pending); |
| 2125 | |
| 2126 | p->utime = p->stime = p->gtime = 0; |
| 2127 | #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME |
| 2128 | p->utimescaled = p->stimescaled = 0; |
| 2129 | #endif |
| 2130 | prev_cputime_init(&p->prev_cputime); |
| 2131 | |
| 2132 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN |
| 2133 | seqcount_init(&p->vtime.seqcount); |
| 2134 | p->vtime.starttime = 0; |
| 2135 | p->vtime.state = VTIME_INACTIVE; |
| 2136 | #endif |
| 2137 | |
| 2138 | #ifdef CONFIG_IO_URING |
| 2139 | p->io_uring = NULL; |
| 2140 | #endif |
| 2141 | |
| 2142 | #if defined(SPLIT_RSS_COUNTING) |
| 2143 | memset(&p->rss_stat, 0, sizeof(p->rss_stat)); |
| 2144 | #endif |
| 2145 | |
| 2146 | p->default_timer_slack_ns = current->timer_slack_ns; |
| 2147 | |
| 2148 | #ifdef CONFIG_PSI |
| 2149 | p->psi_flags = 0; |
| 2150 | #endif |
| 2151 | |
| 2152 | task_io_accounting_init(&p->ioac); |
| 2153 | acct_clear_integrals(p); |
| 2154 | |
| 2155 | posix_cputimers_init(&p->posix_cputimers); |
| 2156 | |
| 2157 | p->io_context = NULL; |
| 2158 | audit_set_context(p, NULL); |
| 2159 | cgroup_fork(p); |
| 2160 | if (p->flags & PF_KTHREAD) { |
| 2161 | if (!set_kthread_struct(p)) |
| 2162 | goto bad_fork_cleanup_delayacct; |
| 2163 | } |
| 2164 | #ifdef CONFIG_NUMA |
| 2165 | p->mempolicy = mpol_dup(p->mempolicy); |
| 2166 | if (IS_ERR(p->mempolicy)) { |
| 2167 | retval = PTR_ERR(p->mempolicy); |
| 2168 | p->mempolicy = NULL; |
| 2169 | goto bad_fork_cleanup_delayacct; |
| 2170 | } |
| 2171 | #endif |
| 2172 | #ifdef CONFIG_CPUSETS |
| 2173 | p->cpuset_mem_spread_rotor = NUMA_NO_NODE; |
| 2174 | p->cpuset_slab_spread_rotor = NUMA_NO_NODE; |
| 2175 | seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock); |
| 2176 | #endif |
| 2177 | #ifdef CONFIG_TRACE_IRQFLAGS |
| 2178 | memset(&p->irqtrace, 0, sizeof(p->irqtrace)); |
| 2179 | p->irqtrace.hardirq_disable_ip = _THIS_IP_; |
| 2180 | p->irqtrace.softirq_enable_ip = _THIS_IP_; |
| 2181 | p->softirqs_enabled = 1; |
| 2182 | p->softirq_context = 0; |
| 2183 | #endif |
| 2184 | |
| 2185 | p->pagefault_disabled = 0; |
| 2186 | |
| 2187 | #ifdef CONFIG_LOCKDEP |
| 2188 | lockdep_init_task(p); |
| 2189 | #endif |
| 2190 | |
| 2191 | #ifdef CONFIG_DEBUG_MUTEXES |
| 2192 | p->blocked_on = NULL; /* not blocked yet */ |
| 2193 | #endif |
| 2194 | #ifdef CONFIG_BCACHE |
| 2195 | p->sequential_io = 0; |
| 2196 | p->sequential_io_avg = 0; |
| 2197 | #endif |
| 2198 | #ifdef CONFIG_BPF_SYSCALL |
| 2199 | RCU_INIT_POINTER(p->bpf_storage, NULL); |
| 2200 | p->bpf_ctx = NULL; |
| 2201 | #endif |
| 2202 | |
| 2203 | /* Perform scheduler related setup. Assign this task to a CPU. */ |
| 2204 | retval = sched_fork(clone_flags, p); |
| 2205 | if (retval) |
| 2206 | goto bad_fork_cleanup_policy; |
| 2207 | |
| 2208 | retval = perf_event_init_task(p, clone_flags); |
| 2209 | if (retval) |
| 2210 | goto bad_fork_cleanup_policy; |
| 2211 | retval = audit_alloc(p); |
| 2212 | if (retval) |
| 2213 | goto bad_fork_cleanup_perf; |
| 2214 | /* copy all the process information */ |
| 2215 | shm_init_task(p); |
| 2216 | retval = security_task_alloc(p, clone_flags); |
| 2217 | if (retval) |
| 2218 | goto bad_fork_cleanup_audit; |
| 2219 | retval = copy_semundo(clone_flags, p); |
| 2220 | if (retval) |
| 2221 | goto bad_fork_cleanup_security; |
| 2222 | retval = copy_files(clone_flags, p); |
| 2223 | if (retval) |
| 2224 | goto bad_fork_cleanup_semundo; |
| 2225 | retval = copy_fs(clone_flags, p); |
| 2226 | if (retval) |
| 2227 | goto bad_fork_cleanup_files; |
| 2228 | retval = copy_sighand(clone_flags, p); |
| 2229 | if (retval) |
| 2230 | goto bad_fork_cleanup_fs; |
| 2231 | retval = copy_signal(clone_flags, p); |
| 2232 | if (retval) |
| 2233 | goto bad_fork_cleanup_sighand; |
| 2234 | retval = copy_mm(clone_flags, p); |
| 2235 | if (retval) |
| 2236 | goto bad_fork_cleanup_signal; |
| 2237 | retval = copy_namespaces(clone_flags, p); |
| 2238 | if (retval) |
| 2239 | goto bad_fork_cleanup_mm; |
| 2240 | retval = copy_io(clone_flags, p); |
| 2241 | if (retval) |
| 2242 | goto bad_fork_cleanup_namespaces; |
| 2243 | retval = copy_thread(clone_flags, args->stack, args->stack_size, p, args->tls); |
| 2244 | if (retval) |
| 2245 | goto bad_fork_cleanup_io; |
| 2246 | |
| 2247 | stackleak_task_init(p); |
| 2248 | |
| 2249 | if (pid != &init_struct_pid) { |
| 2250 | pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid, |
| 2251 | args->set_tid_size); |
| 2252 | if (IS_ERR(pid)) { |
| 2253 | retval = PTR_ERR(pid); |
| 2254 | goto bad_fork_cleanup_thread; |
| 2255 | } |
| 2256 | } |
| 2257 | |
| 2258 | /* |
| 2259 | * This has to happen after we've potentially unshared the file |
| 2260 | * descriptor table (so that the pidfd doesn't leak into the child |
| 2261 | * if the fd table isn't shared). |
| 2262 | */ |
| 2263 | if (clone_flags & CLONE_PIDFD) { |
| 2264 | retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC); |
| 2265 | if (retval < 0) |
| 2266 | goto bad_fork_free_pid; |
| 2267 | |
| 2268 | pidfd = retval; |
| 2269 | |
| 2270 | pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid, |
| 2271 | O_RDWR | O_CLOEXEC); |
| 2272 | if (IS_ERR(pidfile)) { |
| 2273 | put_unused_fd(pidfd); |
| 2274 | retval = PTR_ERR(pidfile); |
| 2275 | goto bad_fork_free_pid; |
| 2276 | } |
| 2277 | get_pid(pid); /* held by pidfile now */ |
| 2278 | |
| 2279 | retval = put_user(pidfd, args->pidfd); |
| 2280 | if (retval) |
| 2281 | goto bad_fork_put_pidfd; |
| 2282 | } |
| 2283 | |
| 2284 | #ifdef CONFIG_BLOCK |
| 2285 | p->plug = NULL; |
| 2286 | #endif |
| 2287 | futex_init_task(p); |
| 2288 | |
| 2289 | /* |
| 2290 | * sigaltstack should be cleared when sharing the same VM |
| 2291 | */ |
| 2292 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) |
| 2293 | sas_ss_reset(p); |
| 2294 | |
| 2295 | /* |
| 2296 | * Syscall tracing and stepping should be turned off in the |
| 2297 | * child regardless of CLONE_PTRACE. |
| 2298 | */ |
| 2299 | user_disable_single_step(p); |
| 2300 | clear_task_syscall_work(p, SYSCALL_TRACE); |
| 2301 | #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU) |
| 2302 | clear_task_syscall_work(p, SYSCALL_EMU); |
| 2303 | #endif |
| 2304 | clear_tsk_latency_tracing(p); |
| 2305 | |
| 2306 | /* ok, now we should be set up.. */ |
| 2307 | p->pid = pid_nr(pid); |
| 2308 | if (clone_flags & CLONE_THREAD) { |
| 2309 | p->group_leader = current->group_leader; |
| 2310 | p->tgid = current->tgid; |
| 2311 | } else { |
| 2312 | p->group_leader = p; |
| 2313 | p->tgid = p->pid; |
| 2314 | } |
| 2315 | |
| 2316 | p->nr_dirtied = 0; |
| 2317 | p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10); |
| 2318 | p->dirty_paused_when = 0; |
| 2319 | |
| 2320 | p->pdeath_signal = 0; |
| 2321 | INIT_LIST_HEAD(&p->thread_group); |
| 2322 | p->task_works = NULL; |
| 2323 | clear_posix_cputimers_work(p); |
| 2324 | |
| 2325 | #ifdef CONFIG_KRETPROBES |
| 2326 | p->kretprobe_instances.first = NULL; |
| 2327 | #endif |
| 2328 | #ifdef CONFIG_RETHOOK |
| 2329 | p->rethooks.first = NULL; |
| 2330 | #endif |
| 2331 | |
| 2332 | /* |
| 2333 | * Ensure that the cgroup subsystem policies allow the new process to be |
| 2334 | * forked. It should be noted that the new process's css_set can be changed |
| 2335 | * between here and cgroup_post_fork() if an organisation operation is in |
| 2336 | * progress. |
| 2337 | */ |
| 2338 | retval = cgroup_can_fork(p, args); |
| 2339 | if (retval) |
| 2340 | goto bad_fork_put_pidfd; |
| 2341 | |
| 2342 | /* |
| 2343 | * Now that the cgroups are pinned, re-clone the parent cgroup and put |
| 2344 | * the new task on the correct runqueue. All this *before* the task |
| 2345 | * becomes visible. |
| 2346 | * |
| 2347 | * This isn't part of ->can_fork() because while the re-cloning is |
| 2348 | * cgroup specific, it unconditionally needs to place the task on a |
| 2349 | * runqueue. |
| 2350 | */ |
| 2351 | sched_cgroup_fork(p, args); |
| 2352 | |
| 2353 | /* |
| 2354 | * From this point on we must avoid any synchronous user-space |
| 2355 | * communication until we take the tasklist-lock. In particular, we do |
| 2356 | * not want user-space to be able to predict the process start-time by |
| 2357 | * stalling fork(2) after we recorded the start_time but before it is |
| 2358 | * visible to the system. |
| 2359 | */ |
| 2360 | |
| 2361 | p->start_time = ktime_get_ns(); |
| 2362 | p->start_boottime = ktime_get_boottime_ns(); |
| 2363 | |
| 2364 | /* |
| 2365 | * Make it visible to the rest of the system, but dont wake it up yet. |
| 2366 | * Need tasklist lock for parent etc handling! |
| 2367 | */ |
| 2368 | write_lock_irq(&tasklist_lock); |
| 2369 | |
| 2370 | /* CLONE_PARENT re-uses the old parent */ |
| 2371 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { |
| 2372 | p->real_parent = current->real_parent; |
| 2373 | p->parent_exec_id = current->parent_exec_id; |
| 2374 | if (clone_flags & CLONE_THREAD) |
| 2375 | p->exit_signal = -1; |
| 2376 | else |
| 2377 | p->exit_signal = current->group_leader->exit_signal; |
| 2378 | } else { |
| 2379 | p->real_parent = current; |
| 2380 | p->parent_exec_id = current->self_exec_id; |
| 2381 | p->exit_signal = args->exit_signal; |
| 2382 | } |
| 2383 | |
| 2384 | klp_copy_process(p); |
| 2385 | |
| 2386 | sched_core_fork(p); |
| 2387 | |
| 2388 | spin_lock(¤t->sighand->siglock); |
| 2389 | |
| 2390 | /* |
| 2391 | * Copy seccomp details explicitly here, in case they were changed |
| 2392 | * before holding sighand lock. |
| 2393 | */ |
| 2394 | copy_seccomp(p); |
| 2395 | |
| 2396 | rseq_fork(p, clone_flags); |
| 2397 | |
| 2398 | /* Don't start children in a dying pid namespace */ |
| 2399 | if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) { |
| 2400 | retval = -ENOMEM; |
| 2401 | goto bad_fork_cancel_cgroup; |
| 2402 | } |
| 2403 | |
| 2404 | /* Let kill terminate clone/fork in the middle */ |
| 2405 | if (fatal_signal_pending(current)) { |
| 2406 | retval = -EINTR; |
| 2407 | goto bad_fork_cancel_cgroup; |
| 2408 | } |
| 2409 | |
| 2410 | init_task_pid_links(p); |
| 2411 | if (likely(p->pid)) { |
| 2412 | ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace); |
| 2413 | |
| 2414 | init_task_pid(p, PIDTYPE_PID, pid); |
| 2415 | if (thread_group_leader(p)) { |
| 2416 | init_task_pid(p, PIDTYPE_TGID, pid); |
| 2417 | init_task_pid(p, PIDTYPE_PGID, task_pgrp(current)); |
| 2418 | init_task_pid(p, PIDTYPE_SID, task_session(current)); |
| 2419 | |
| 2420 | if (is_child_reaper(pid)) { |
| 2421 | ns_of_pid(pid)->child_reaper = p; |
| 2422 | p->signal->flags |= SIGNAL_UNKILLABLE; |
| 2423 | } |
| 2424 | p->signal->shared_pending.signal = delayed.signal; |
| 2425 | p->signal->tty = tty_kref_get(current->signal->tty); |
| 2426 | /* |
| 2427 | * Inherit has_child_subreaper flag under the same |
| 2428 | * tasklist_lock with adding child to the process tree |
| 2429 | * for propagate_has_child_subreaper optimization. |
| 2430 | */ |
| 2431 | p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper || |
| 2432 | p->real_parent->signal->is_child_subreaper; |
| 2433 | list_add_tail(&p->sibling, &p->real_parent->children); |
| 2434 | list_add_tail_rcu(&p->tasks, &init_task.tasks); |
| 2435 | attach_pid(p, PIDTYPE_TGID); |
| 2436 | attach_pid(p, PIDTYPE_PGID); |
| 2437 | attach_pid(p, PIDTYPE_SID); |
| 2438 | __this_cpu_inc(process_counts); |
| 2439 | } else { |
| 2440 | current->signal->nr_threads++; |
| 2441 | atomic_inc(¤t->signal->live); |
| 2442 | refcount_inc(¤t->signal->sigcnt); |
| 2443 | task_join_group_stop(p); |
| 2444 | list_add_tail_rcu(&p->thread_group, |
| 2445 | &p->group_leader->thread_group); |
| 2446 | list_add_tail_rcu(&p->thread_node, |
| 2447 | &p->signal->thread_head); |
| 2448 | } |
| 2449 | attach_pid(p, PIDTYPE_PID); |
| 2450 | nr_threads++; |
| 2451 | } |
| 2452 | total_forks++; |
| 2453 | hlist_del_init(&delayed.node); |
| 2454 | spin_unlock(¤t->sighand->siglock); |
| 2455 | syscall_tracepoint_update(p); |
| 2456 | write_unlock_irq(&tasklist_lock); |
| 2457 | |
| 2458 | if (pidfile) |
| 2459 | fd_install(pidfd, pidfile); |
| 2460 | |
| 2461 | proc_fork_connector(p); |
| 2462 | sched_post_fork(p); |
| 2463 | cgroup_post_fork(p, args); |
| 2464 | perf_event_fork(p); |
| 2465 | |
| 2466 | trace_task_newtask(p, clone_flags); |
| 2467 | uprobe_copy_process(p, clone_flags); |
| 2468 | |
| 2469 | copy_oom_score_adj(clone_flags, p); |
| 2470 | |
| 2471 | return p; |
| 2472 | |
| 2473 | bad_fork_cancel_cgroup: |
| 2474 | sched_core_free(p); |
| 2475 | spin_unlock(¤t->sighand->siglock); |
| 2476 | write_unlock_irq(&tasklist_lock); |
| 2477 | cgroup_cancel_fork(p, args); |
| 2478 | bad_fork_put_pidfd: |
| 2479 | if (clone_flags & CLONE_PIDFD) { |
| 2480 | fput(pidfile); |
| 2481 | put_unused_fd(pidfd); |
| 2482 | } |
| 2483 | bad_fork_free_pid: |
| 2484 | if (pid != &init_struct_pid) |
| 2485 | free_pid(pid); |
| 2486 | bad_fork_cleanup_thread: |
| 2487 | exit_thread(p); |
| 2488 | bad_fork_cleanup_io: |
| 2489 | if (p->io_context) |
| 2490 | exit_io_context(p); |
| 2491 | bad_fork_cleanup_namespaces: |
| 2492 | exit_task_namespaces(p); |
| 2493 | bad_fork_cleanup_mm: |
| 2494 | if (p->mm) { |
| 2495 | mm_clear_owner(p->mm, p); |
| 2496 | mmput(p->mm); |
| 2497 | } |
| 2498 | bad_fork_cleanup_signal: |
| 2499 | if (!(clone_flags & CLONE_THREAD)) |
| 2500 | free_signal_struct(p->signal); |
| 2501 | bad_fork_cleanup_sighand: |
| 2502 | __cleanup_sighand(p->sighand); |
| 2503 | bad_fork_cleanup_fs: |
| 2504 | exit_fs(p); /* blocking */ |
| 2505 | bad_fork_cleanup_files: |
| 2506 | exit_files(p); /* blocking */ |
| 2507 | bad_fork_cleanup_semundo: |
| 2508 | exit_sem(p); |
| 2509 | bad_fork_cleanup_security: |
| 2510 | security_task_free(p); |
| 2511 | bad_fork_cleanup_audit: |
| 2512 | audit_free(p); |
| 2513 | bad_fork_cleanup_perf: |
| 2514 | perf_event_free_task(p); |
| 2515 | bad_fork_cleanup_policy: |
| 2516 | lockdep_free_task(p); |
| 2517 | #ifdef CONFIG_NUMA |
| 2518 | mpol_put(p->mempolicy); |
| 2519 | #endif |
| 2520 | bad_fork_cleanup_delayacct: |
| 2521 | delayacct_tsk_free(p); |
| 2522 | bad_fork_cleanup_count: |
| 2523 | dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); |
| 2524 | exit_creds(p); |
| 2525 | bad_fork_free: |
| 2526 | WRITE_ONCE(p->__state, TASK_DEAD); |
| 2527 | exit_task_stack_account(p); |
| 2528 | put_task_stack(p); |
| 2529 | delayed_free_task(p); |
| 2530 | fork_out: |
| 2531 | spin_lock_irq(¤t->sighand->siglock); |
| 2532 | hlist_del_init(&delayed.node); |
| 2533 | spin_unlock_irq(¤t->sighand->siglock); |
| 2534 | return ERR_PTR(retval); |
| 2535 | } |
| 2536 | |
| 2537 | static inline void init_idle_pids(struct task_struct *idle) |
| 2538 | { |
| 2539 | enum pid_type type; |
| 2540 | |
| 2541 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { |
| 2542 | INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */ |
| 2543 | init_task_pid(idle, type, &init_struct_pid); |
| 2544 | } |
| 2545 | } |
| 2546 | |
| 2547 | struct task_struct * __init fork_idle(int cpu) |
| 2548 | { |
| 2549 | struct task_struct *task; |
| 2550 | struct kernel_clone_args args = { |
| 2551 | .flags = CLONE_VM, |
| 2552 | }; |
| 2553 | |
| 2554 | task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args); |
| 2555 | if (!IS_ERR(task)) { |
| 2556 | init_idle_pids(task); |
| 2557 | init_idle(task, cpu); |
| 2558 | } |
| 2559 | |
| 2560 | return task; |
| 2561 | } |
| 2562 | |
| 2563 | struct mm_struct *copy_init_mm(void) |
| 2564 | { |
| 2565 | return dup_mm(NULL, &init_mm); |
| 2566 | } |
| 2567 | |
| 2568 | /* |
| 2569 | * This is like kernel_clone(), but shaved down and tailored to just |
| 2570 | * creating io_uring workers. It returns a created task, or an error pointer. |
| 2571 | * The returned task is inactive, and the caller must fire it up through |
| 2572 | * wake_up_new_task(p). All signals are blocked in the created task. |
| 2573 | */ |
| 2574 | struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node) |
| 2575 | { |
| 2576 | unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD| |
| 2577 | CLONE_IO; |
| 2578 | struct kernel_clone_args args = { |
| 2579 | .flags = ((lower_32_bits(flags) | CLONE_VM | |
| 2580 | CLONE_UNTRACED) & ~CSIGNAL), |
| 2581 | .exit_signal = (lower_32_bits(flags) & CSIGNAL), |
| 2582 | .stack = (unsigned long)fn, |
| 2583 | .stack_size = (unsigned long)arg, |
| 2584 | .io_thread = 1, |
| 2585 | }; |
| 2586 | |
| 2587 | return copy_process(NULL, 0, node, &args); |
| 2588 | } |
| 2589 | |
| 2590 | /* |
| 2591 | * Ok, this is the main fork-routine. |
| 2592 | * |
| 2593 | * It copies the process, and if successful kick-starts |
| 2594 | * it and waits for it to finish using the VM if required. |
| 2595 | * |
| 2596 | * args->exit_signal is expected to be checked for sanity by the caller. |
| 2597 | */ |
| 2598 | pid_t kernel_clone(struct kernel_clone_args *args) |
| 2599 | { |
| 2600 | u64 clone_flags = args->flags; |
| 2601 | struct completion vfork; |
| 2602 | struct pid *pid; |
| 2603 | struct task_struct *p; |
| 2604 | int trace = 0; |
| 2605 | pid_t nr; |
| 2606 | |
| 2607 | /* |
| 2608 | * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument |
| 2609 | * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are |
| 2610 | * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate |
| 2611 | * field in struct clone_args and it still doesn't make sense to have |
| 2612 | * them both point at the same memory location. Performing this check |
| 2613 | * here has the advantage that we don't need to have a separate helper |
| 2614 | * to check for legacy clone(). |
| 2615 | */ |
| 2616 | if ((args->flags & CLONE_PIDFD) && |
| 2617 | (args->flags & CLONE_PARENT_SETTID) && |
| 2618 | (args->pidfd == args->parent_tid)) |
| 2619 | return -EINVAL; |
| 2620 | |
| 2621 | /* |
| 2622 | * Determine whether and which event to report to ptracer. When |
| 2623 | * called from kernel_thread or CLONE_UNTRACED is explicitly |
| 2624 | * requested, no event is reported; otherwise, report if the event |
| 2625 | * for the type of forking is enabled. |
| 2626 | */ |
| 2627 | if (!(clone_flags & CLONE_UNTRACED)) { |
| 2628 | if (clone_flags & CLONE_VFORK) |
| 2629 | trace = PTRACE_EVENT_VFORK; |
| 2630 | else if (args->exit_signal != SIGCHLD) |
| 2631 | trace = PTRACE_EVENT_CLONE; |
| 2632 | else |
| 2633 | trace = PTRACE_EVENT_FORK; |
| 2634 | |
| 2635 | if (likely(!ptrace_event_enabled(current, trace))) |
| 2636 | trace = 0; |
| 2637 | } |
| 2638 | |
| 2639 | p = copy_process(NULL, trace, NUMA_NO_NODE, args); |
| 2640 | add_latent_entropy(); |
| 2641 | |
| 2642 | if (IS_ERR(p)) |
| 2643 | return PTR_ERR(p); |
| 2644 | |
| 2645 | /* |
| 2646 | * Do this prior waking up the new thread - the thread pointer |
| 2647 | * might get invalid after that point, if the thread exits quickly. |
| 2648 | */ |
| 2649 | trace_sched_process_fork(current, p); |
| 2650 | |
| 2651 | pid = get_task_pid(p, PIDTYPE_PID); |
| 2652 | nr = pid_vnr(pid); |
| 2653 | |
| 2654 | if (clone_flags & CLONE_PARENT_SETTID) |
| 2655 | put_user(nr, args->parent_tid); |
| 2656 | |
| 2657 | if (clone_flags & CLONE_VFORK) { |
| 2658 | p->vfork_done = &vfork; |
| 2659 | init_completion(&vfork); |
| 2660 | get_task_struct(p); |
| 2661 | } |
| 2662 | |
| 2663 | wake_up_new_task(p); |
| 2664 | |
| 2665 | /* forking complete and child started to run, tell ptracer */ |
| 2666 | if (unlikely(trace)) |
| 2667 | ptrace_event_pid(trace, pid); |
| 2668 | |
| 2669 | if (clone_flags & CLONE_VFORK) { |
| 2670 | if (!wait_for_vfork_done(p, &vfork)) |
| 2671 | ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid); |
| 2672 | } |
| 2673 | |
| 2674 | put_pid(pid); |
| 2675 | return nr; |
| 2676 | } |
| 2677 | |
| 2678 | /* |
| 2679 | * Create a kernel thread. |
| 2680 | */ |
| 2681 | pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) |
| 2682 | { |
| 2683 | struct kernel_clone_args args = { |
| 2684 | .flags = ((lower_32_bits(flags) | CLONE_VM | |
| 2685 | CLONE_UNTRACED) & ~CSIGNAL), |
| 2686 | .exit_signal = (lower_32_bits(flags) & CSIGNAL), |
| 2687 | .stack = (unsigned long)fn, |
| 2688 | .stack_size = (unsigned long)arg, |
| 2689 | }; |
| 2690 | |
| 2691 | return kernel_clone(&args); |
| 2692 | } |
| 2693 | |
| 2694 | #ifdef __ARCH_WANT_SYS_FORK |
| 2695 | SYSCALL_DEFINE0(fork) |
| 2696 | { |
| 2697 | #ifdef CONFIG_MMU |
| 2698 | struct kernel_clone_args args = { |
| 2699 | .exit_signal = SIGCHLD, |
| 2700 | }; |
| 2701 | |
| 2702 | return kernel_clone(&args); |
| 2703 | #else |
| 2704 | /* can not support in nommu mode */ |
| 2705 | return -EINVAL; |
| 2706 | #endif |
| 2707 | } |
| 2708 | #endif |
| 2709 | |
| 2710 | #ifdef __ARCH_WANT_SYS_VFORK |
| 2711 | SYSCALL_DEFINE0(vfork) |
| 2712 | { |
| 2713 | struct kernel_clone_args args = { |
| 2714 | .flags = CLONE_VFORK | CLONE_VM, |
| 2715 | .exit_signal = SIGCHLD, |
| 2716 | }; |
| 2717 | |
| 2718 | return kernel_clone(&args); |
| 2719 | } |
| 2720 | #endif |
| 2721 | |
| 2722 | #ifdef __ARCH_WANT_SYS_CLONE |
| 2723 | #ifdef CONFIG_CLONE_BACKWARDS |
| 2724 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, |
| 2725 | int __user *, parent_tidptr, |
| 2726 | unsigned long, tls, |
| 2727 | int __user *, child_tidptr) |
| 2728 | #elif defined(CONFIG_CLONE_BACKWARDS2) |
| 2729 | SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags, |
| 2730 | int __user *, parent_tidptr, |
| 2731 | int __user *, child_tidptr, |
| 2732 | unsigned long, tls) |
| 2733 | #elif defined(CONFIG_CLONE_BACKWARDS3) |
| 2734 | SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp, |
| 2735 | int, stack_size, |
| 2736 | int __user *, parent_tidptr, |
| 2737 | int __user *, child_tidptr, |
| 2738 | unsigned long, tls) |
| 2739 | #else |
| 2740 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, |
| 2741 | int __user *, parent_tidptr, |
| 2742 | int __user *, child_tidptr, |
| 2743 | unsigned long, tls) |
| 2744 | #endif |
| 2745 | { |
| 2746 | struct kernel_clone_args args = { |
| 2747 | .flags = (lower_32_bits(clone_flags) & ~CSIGNAL), |
| 2748 | .pidfd = parent_tidptr, |
| 2749 | .child_tid = child_tidptr, |
| 2750 | .parent_tid = parent_tidptr, |
| 2751 | .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL), |
| 2752 | .stack = newsp, |
| 2753 | .tls = tls, |
| 2754 | }; |
| 2755 | |
| 2756 | return kernel_clone(&args); |
| 2757 | } |
| 2758 | #endif |
| 2759 | |
| 2760 | #ifdef __ARCH_WANT_SYS_CLONE3 |
| 2761 | |
| 2762 | noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, |
| 2763 | struct clone_args __user *uargs, |
| 2764 | size_t usize) |
| 2765 | { |
| 2766 | int err; |
| 2767 | struct clone_args args; |
| 2768 | pid_t *kset_tid = kargs->set_tid; |
| 2769 | |
| 2770 | BUILD_BUG_ON(offsetofend(struct clone_args, tls) != |
| 2771 | CLONE_ARGS_SIZE_VER0); |
| 2772 | BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) != |
| 2773 | CLONE_ARGS_SIZE_VER1); |
| 2774 | BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) != |
| 2775 | CLONE_ARGS_SIZE_VER2); |
| 2776 | BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2); |
| 2777 | |
| 2778 | if (unlikely(usize > PAGE_SIZE)) |
| 2779 | return -E2BIG; |
| 2780 | if (unlikely(usize < CLONE_ARGS_SIZE_VER0)) |
| 2781 | return -EINVAL; |
| 2782 | |
| 2783 | err = copy_struct_from_user(&args, sizeof(args), uargs, usize); |
| 2784 | if (err) |
| 2785 | return err; |
| 2786 | |
| 2787 | if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL)) |
| 2788 | return -EINVAL; |
| 2789 | |
| 2790 | if (unlikely(!args.set_tid && args.set_tid_size > 0)) |
| 2791 | return -EINVAL; |
| 2792 | |
| 2793 | if (unlikely(args.set_tid && args.set_tid_size == 0)) |
| 2794 | return -EINVAL; |
| 2795 | |
| 2796 | /* |
| 2797 | * Verify that higher 32bits of exit_signal are unset and that |
| 2798 | * it is a valid signal |
| 2799 | */ |
| 2800 | if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) || |
| 2801 | !valid_signal(args.exit_signal))) |
| 2802 | return -EINVAL; |
| 2803 | |
| 2804 | if ((args.flags & CLONE_INTO_CGROUP) && |
| 2805 | (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2)) |
| 2806 | return -EINVAL; |
| 2807 | |
| 2808 | *kargs = (struct kernel_clone_args){ |
| 2809 | .flags = args.flags, |
| 2810 | .pidfd = u64_to_user_ptr(args.pidfd), |
| 2811 | .child_tid = u64_to_user_ptr(args.child_tid), |
| 2812 | .parent_tid = u64_to_user_ptr(args.parent_tid), |
| 2813 | .exit_signal = args.exit_signal, |
| 2814 | .stack = args.stack, |
| 2815 | .stack_size = args.stack_size, |
| 2816 | .tls = args.tls, |
| 2817 | .set_tid_size = args.set_tid_size, |
| 2818 | .cgroup = args.cgroup, |
| 2819 | }; |
| 2820 | |
| 2821 | if (args.set_tid && |
| 2822 | copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid), |
| 2823 | (kargs->set_tid_size * sizeof(pid_t)))) |
| 2824 | return -EFAULT; |
| 2825 | |
| 2826 | kargs->set_tid = kset_tid; |
| 2827 | |
| 2828 | return 0; |
| 2829 | } |
| 2830 | |
| 2831 | /** |
| 2832 | * clone3_stack_valid - check and prepare stack |
| 2833 | * @kargs: kernel clone args |
| 2834 | * |
| 2835 | * Verify that the stack arguments userspace gave us are sane. |
| 2836 | * In addition, set the stack direction for userspace since it's easy for us to |
| 2837 | * determine. |
| 2838 | */ |
| 2839 | static inline bool clone3_stack_valid(struct kernel_clone_args *kargs) |
| 2840 | { |
| 2841 | if (kargs->stack == 0) { |
| 2842 | if (kargs->stack_size > 0) |
| 2843 | return false; |
| 2844 | } else { |
| 2845 | if (kargs->stack_size == 0) |
| 2846 | return false; |
| 2847 | |
| 2848 | if (!access_ok((void __user *)kargs->stack, kargs->stack_size)) |
| 2849 | return false; |
| 2850 | |
| 2851 | #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64) |
| 2852 | kargs->stack += kargs->stack_size; |
| 2853 | #endif |
| 2854 | } |
| 2855 | |
| 2856 | return true; |
| 2857 | } |
| 2858 | |
| 2859 | static bool clone3_args_valid(struct kernel_clone_args *kargs) |
| 2860 | { |
| 2861 | /* Verify that no unknown flags are passed along. */ |
| 2862 | if (kargs->flags & |
| 2863 | ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP)) |
| 2864 | return false; |
| 2865 | |
| 2866 | /* |
| 2867 | * - make the CLONE_DETACHED bit reusable for clone3 |
| 2868 | * - make the CSIGNAL bits reusable for clone3 |
| 2869 | */ |
| 2870 | if (kargs->flags & (CLONE_DETACHED | CSIGNAL)) |
| 2871 | return false; |
| 2872 | |
| 2873 | if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) == |
| 2874 | (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) |
| 2875 | return false; |
| 2876 | |
| 2877 | if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) && |
| 2878 | kargs->exit_signal) |
| 2879 | return false; |
| 2880 | |
| 2881 | if (!clone3_stack_valid(kargs)) |
| 2882 | return false; |
| 2883 | |
| 2884 | return true; |
| 2885 | } |
| 2886 | |
| 2887 | /** |
| 2888 | * clone3 - create a new process with specific properties |
| 2889 | * @uargs: argument structure |
| 2890 | * @size: size of @uargs |
| 2891 | * |
| 2892 | * clone3() is the extensible successor to clone()/clone2(). |
| 2893 | * It takes a struct as argument that is versioned by its size. |
| 2894 | * |
| 2895 | * Return: On success, a positive PID for the child process. |
| 2896 | * On error, a negative errno number. |
| 2897 | */ |
| 2898 | SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size) |
| 2899 | { |
| 2900 | int err; |
| 2901 | |
| 2902 | struct kernel_clone_args kargs; |
| 2903 | pid_t set_tid[MAX_PID_NS_LEVEL]; |
| 2904 | |
| 2905 | kargs.set_tid = set_tid; |
| 2906 | |
| 2907 | err = copy_clone_args_from_user(&kargs, uargs, size); |
| 2908 | if (err) |
| 2909 | return err; |
| 2910 | |
| 2911 | if (!clone3_args_valid(&kargs)) |
| 2912 | return -EINVAL; |
| 2913 | |
| 2914 | return kernel_clone(&kargs); |
| 2915 | } |
| 2916 | #endif |
| 2917 | |
| 2918 | void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data) |
| 2919 | { |
| 2920 | struct task_struct *leader, *parent, *child; |
| 2921 | int res; |
| 2922 | |
| 2923 | read_lock(&tasklist_lock); |
| 2924 | leader = top = top->group_leader; |
| 2925 | down: |
| 2926 | for_each_thread(leader, parent) { |
| 2927 | list_for_each_entry(child, &parent->children, sibling) { |
| 2928 | res = visitor(child, data); |
| 2929 | if (res) { |
| 2930 | if (res < 0) |
| 2931 | goto out; |
| 2932 | leader = child; |
| 2933 | goto down; |
| 2934 | } |
| 2935 | up: |
| 2936 | ; |
| 2937 | } |
| 2938 | } |
| 2939 | |
| 2940 | if (leader != top) { |
| 2941 | child = leader; |
| 2942 | parent = child->real_parent; |
| 2943 | leader = parent->group_leader; |
| 2944 | goto up; |
| 2945 | } |
| 2946 | out: |
| 2947 | read_unlock(&tasklist_lock); |
| 2948 | } |
| 2949 | |
| 2950 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN |
| 2951 | #define ARCH_MIN_MMSTRUCT_ALIGN 0 |
| 2952 | #endif |
| 2953 | |
| 2954 | static void sighand_ctor(void *data) |
| 2955 | { |
| 2956 | struct sighand_struct *sighand = data; |
| 2957 | |
| 2958 | spin_lock_init(&sighand->siglock); |
| 2959 | init_waitqueue_head(&sighand->signalfd_wqh); |
| 2960 | } |
| 2961 | |
| 2962 | void __init proc_caches_init(void) |
| 2963 | { |
| 2964 | unsigned int mm_size; |
| 2965 | |
| 2966 | sighand_cachep = kmem_cache_create("sighand_cache", |
| 2967 | sizeof(struct sighand_struct), 0, |
| 2968 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU| |
| 2969 | SLAB_ACCOUNT, sighand_ctor); |
| 2970 | signal_cachep = kmem_cache_create("signal_cache", |
| 2971 | sizeof(struct signal_struct), 0, |
| 2972 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, |
| 2973 | NULL); |
| 2974 | files_cachep = kmem_cache_create("files_cache", |
| 2975 | sizeof(struct files_struct), 0, |
| 2976 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, |
| 2977 | NULL); |
| 2978 | fs_cachep = kmem_cache_create("fs_cache", |
| 2979 | sizeof(struct fs_struct), 0, |
| 2980 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, |
| 2981 | NULL); |
| 2982 | |
| 2983 | /* |
| 2984 | * The mm_cpumask is located at the end of mm_struct, and is |
| 2985 | * dynamically sized based on the maximum CPU number this system |
| 2986 | * can have, taking hotplug into account (nr_cpu_ids). |
| 2987 | */ |
| 2988 | mm_size = sizeof(struct mm_struct) + cpumask_size(); |
| 2989 | |
| 2990 | mm_cachep = kmem_cache_create_usercopy("mm_struct", |
| 2991 | mm_size, ARCH_MIN_MMSTRUCT_ALIGN, |
| 2992 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, |
| 2993 | offsetof(struct mm_struct, saved_auxv), |
| 2994 | sizeof_field(struct mm_struct, saved_auxv), |
| 2995 | NULL); |
| 2996 | vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT); |
| 2997 | mmap_init(); |
| 2998 | nsproxy_cache_init(); |
| 2999 | } |
| 3000 | |
| 3001 | /* |
| 3002 | * Check constraints on flags passed to the unshare system call. |
| 3003 | */ |
| 3004 | static int check_unshare_flags(unsigned long unshare_flags) |
| 3005 | { |
| 3006 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| |
| 3007 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| |
| 3008 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| |
| 3009 | CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP| |
| 3010 | CLONE_NEWTIME)) |
| 3011 | return -EINVAL; |
| 3012 | /* |
| 3013 | * Not implemented, but pretend it works if there is nothing |
| 3014 | * to unshare. Note that unsharing the address space or the |
| 3015 | * signal handlers also need to unshare the signal queues (aka |
| 3016 | * CLONE_THREAD). |
| 3017 | */ |
| 3018 | if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { |
| 3019 | if (!thread_group_empty(current)) |
| 3020 | return -EINVAL; |
| 3021 | } |
| 3022 | if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) { |
| 3023 | if (refcount_read(¤t->sighand->count) > 1) |
| 3024 | return -EINVAL; |
| 3025 | } |
| 3026 | if (unshare_flags & CLONE_VM) { |
| 3027 | if (!current_is_single_threaded()) |
| 3028 | return -EINVAL; |
| 3029 | } |
| 3030 | |
| 3031 | return 0; |
| 3032 | } |
| 3033 | |
| 3034 | /* |
| 3035 | * Unshare the filesystem structure if it is being shared |
| 3036 | */ |
| 3037 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) |
| 3038 | { |
| 3039 | struct fs_struct *fs = current->fs; |
| 3040 | |
| 3041 | if (!(unshare_flags & CLONE_FS) || !fs) |
| 3042 | return 0; |
| 3043 | |
| 3044 | /* don't need lock here; in the worst case we'll do useless copy */ |
| 3045 | if (fs->users == 1) |
| 3046 | return 0; |
| 3047 | |
| 3048 | *new_fsp = copy_fs_struct(fs); |
| 3049 | if (!*new_fsp) |
| 3050 | return -ENOMEM; |
| 3051 | |
| 3052 | return 0; |
| 3053 | } |
| 3054 | |
| 3055 | /* |
| 3056 | * Unshare file descriptor table if it is being shared |
| 3057 | */ |
| 3058 | int unshare_fd(unsigned long unshare_flags, unsigned int max_fds, |
| 3059 | struct files_struct **new_fdp) |
| 3060 | { |
| 3061 | struct files_struct *fd = current->files; |
| 3062 | int error = 0; |
| 3063 | |
| 3064 | if ((unshare_flags & CLONE_FILES) && |
| 3065 | (fd && atomic_read(&fd->count) > 1)) { |
| 3066 | *new_fdp = dup_fd(fd, max_fds, &error); |
| 3067 | if (!*new_fdp) |
| 3068 | return error; |
| 3069 | } |
| 3070 | |
| 3071 | return 0; |
| 3072 | } |
| 3073 | |
| 3074 | /* |
| 3075 | * unshare allows a process to 'unshare' part of the process |
| 3076 | * context which was originally shared using clone. copy_* |
| 3077 | * functions used by kernel_clone() cannot be used here directly |
| 3078 | * because they modify an inactive task_struct that is being |
| 3079 | * constructed. Here we are modifying the current, active, |
| 3080 | * task_struct. |
| 3081 | */ |
| 3082 | int ksys_unshare(unsigned long unshare_flags) |
| 3083 | { |
| 3084 | struct fs_struct *fs, *new_fs = NULL; |
| 3085 | struct files_struct *new_fd = NULL; |
| 3086 | struct cred *new_cred = NULL; |
| 3087 | struct nsproxy *new_nsproxy = NULL; |
| 3088 | int do_sysvsem = 0; |
| 3089 | int err; |
| 3090 | |
| 3091 | /* |
| 3092 | * If unsharing a user namespace must also unshare the thread group |
| 3093 | * and unshare the filesystem root and working directories. |
| 3094 | */ |
| 3095 | if (unshare_flags & CLONE_NEWUSER) |
| 3096 | unshare_flags |= CLONE_THREAD | CLONE_FS; |
| 3097 | /* |
| 3098 | * If unsharing vm, must also unshare signal handlers. |
| 3099 | */ |
| 3100 | if (unshare_flags & CLONE_VM) |
| 3101 | unshare_flags |= CLONE_SIGHAND; |
| 3102 | /* |
| 3103 | * If unsharing a signal handlers, must also unshare the signal queues. |
| 3104 | */ |
| 3105 | if (unshare_flags & CLONE_SIGHAND) |
| 3106 | unshare_flags |= CLONE_THREAD; |
| 3107 | /* |
| 3108 | * If unsharing namespace, must also unshare filesystem information. |
| 3109 | */ |
| 3110 | if (unshare_flags & CLONE_NEWNS) |
| 3111 | unshare_flags |= CLONE_FS; |
| 3112 | |
| 3113 | err = check_unshare_flags(unshare_flags); |
| 3114 | if (err) |
| 3115 | goto bad_unshare_out; |
| 3116 | /* |
| 3117 | * CLONE_NEWIPC must also detach from the undolist: after switching |
| 3118 | * to a new ipc namespace, the semaphore arrays from the old |
| 3119 | * namespace are unreachable. |
| 3120 | */ |
| 3121 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) |
| 3122 | do_sysvsem = 1; |
| 3123 | err = unshare_fs(unshare_flags, &new_fs); |
| 3124 | if (err) |
| 3125 | goto bad_unshare_out; |
| 3126 | err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd); |
| 3127 | if (err) |
| 3128 | goto bad_unshare_cleanup_fs; |
| 3129 | err = unshare_userns(unshare_flags, &new_cred); |
| 3130 | if (err) |
| 3131 | goto bad_unshare_cleanup_fd; |
| 3132 | err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, |
| 3133 | new_cred, new_fs); |
| 3134 | if (err) |
| 3135 | goto bad_unshare_cleanup_cred; |
| 3136 | |
| 3137 | if (new_cred) { |
| 3138 | err = set_cred_ucounts(new_cred); |
| 3139 | if (err) |
| 3140 | goto bad_unshare_cleanup_cred; |
| 3141 | } |
| 3142 | |
| 3143 | if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) { |
| 3144 | if (do_sysvsem) { |
| 3145 | /* |
| 3146 | * CLONE_SYSVSEM is equivalent to sys_exit(). |
| 3147 | */ |
| 3148 | exit_sem(current); |
| 3149 | } |
| 3150 | if (unshare_flags & CLONE_NEWIPC) { |
| 3151 | /* Orphan segments in old ns (see sem above). */ |
| 3152 | exit_shm(current); |
| 3153 | shm_init_task(current); |
| 3154 | } |
| 3155 | |
| 3156 | if (new_nsproxy) |
| 3157 | switch_task_namespaces(current, new_nsproxy); |
| 3158 | |
| 3159 | task_lock(current); |
| 3160 | |
| 3161 | if (new_fs) { |
| 3162 | fs = current->fs; |
| 3163 | spin_lock(&fs->lock); |
| 3164 | current->fs = new_fs; |
| 3165 | if (--fs->users) |
| 3166 | new_fs = NULL; |
| 3167 | else |
| 3168 | new_fs = fs; |
| 3169 | spin_unlock(&fs->lock); |
| 3170 | } |
| 3171 | |
| 3172 | if (new_fd) |
| 3173 | swap(current->files, new_fd); |
| 3174 | |
| 3175 | task_unlock(current); |
| 3176 | |
| 3177 | if (new_cred) { |
| 3178 | /* Install the new user namespace */ |
| 3179 | commit_creds(new_cred); |
| 3180 | new_cred = NULL; |
| 3181 | } |
| 3182 | } |
| 3183 | |
| 3184 | perf_event_namespaces(current); |
| 3185 | |
| 3186 | bad_unshare_cleanup_cred: |
| 3187 | if (new_cred) |
| 3188 | put_cred(new_cred); |
| 3189 | bad_unshare_cleanup_fd: |
| 3190 | if (new_fd) |
| 3191 | put_files_struct(new_fd); |
| 3192 | |
| 3193 | bad_unshare_cleanup_fs: |
| 3194 | if (new_fs) |
| 3195 | free_fs_struct(new_fs); |
| 3196 | |
| 3197 | bad_unshare_out: |
| 3198 | return err; |
| 3199 | } |
| 3200 | |
| 3201 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) |
| 3202 | { |
| 3203 | return ksys_unshare(unshare_flags); |
| 3204 | } |
| 3205 | |
| 3206 | /* |
| 3207 | * Helper to unshare the files of the current task. |
| 3208 | * We don't want to expose copy_files internals to |
| 3209 | * the exec layer of the kernel. |
| 3210 | */ |
| 3211 | |
| 3212 | int unshare_files(void) |
| 3213 | { |
| 3214 | struct task_struct *task = current; |
| 3215 | struct files_struct *old, *copy = NULL; |
| 3216 | int error; |
| 3217 | |
| 3218 | error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©); |
| 3219 | if (error || !copy) |
| 3220 | return error; |
| 3221 | |
| 3222 | old = task->files; |
| 3223 | task_lock(task); |
| 3224 | task->files = copy; |
| 3225 | task_unlock(task); |
| 3226 | put_files_struct(old); |
| 3227 | return 0; |
| 3228 | } |
| 3229 | |
| 3230 | int sysctl_max_threads(struct ctl_table *table, int write, |
| 3231 | void *buffer, size_t *lenp, loff_t *ppos) |
| 3232 | { |
| 3233 | struct ctl_table t; |
| 3234 | int ret; |
| 3235 | int threads = max_threads; |
| 3236 | int min = 1; |
| 3237 | int max = MAX_THREADS; |
| 3238 | |
| 3239 | t = *table; |
| 3240 | t.data = &threads; |
| 3241 | t.extra1 = &min; |
| 3242 | t.extra2 = &max; |
| 3243 | |
| 3244 | ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); |
| 3245 | if (ret || !write) |
| 3246 | return ret; |
| 3247 | |
| 3248 | max_threads = threads; |
| 3249 | |
| 3250 | return 0; |
| 3251 | } |