fs/exec.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/fs/exec.c
   4  *
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  */
   7
   8 /*
   9  * #!-checking implemented by tytso.
  10  */
  11 /*
  12  * Demand-loading implemented 01.12.91 - no need to read anything but
  13  * the header into memory. The inode of the executable is put into
  14  * "current->executable", and page faults do the actual loading. Clean.
  15  *
  16  * Once more I can proudly say that linux stood up to being changed: it
  17  * was less than 2 hours work to get demand-loading completely implemented.
  18  *
  19  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  20  * current->executable is only used by the procfs.  This allows a dispatch
  21  * table to check for several different types  of binary formats.  We keep
  22  * trying until we recognize the file or we run out of supported binary
  23  * formats.
  24  */
  25
  26 #include <linux/kernel_read_file.h>
  27 #include <linux/slab.h>
  28 #include <linux/file.h>
  29 #include <linux/fdtable.h>
  30 #include <linux/mm.h>
  31 #include <linux/stat.h>
  32 #include <linux/fcntl.h>
  33 #include <linux/swap.h>
  34 #include <linux/string.h>
  35 #include <linux/init.h>
  36 #include <linux/sched/mm.h>
  37 #include <linux/sched/coredump.h>
  38 #include <linux/sched/signal.h>
  39 #include <linux/sched/numa_balancing.h>
  40 #include <linux/sched/task.h>
  41 #include <linux/pagemap.h>
  42 #include <linux/perf_event.h>
  43 #include <linux/highmem.h>
  44 #include <linux/spinlock.h>
  45 #include <linux/key.h>
  46 #include <linux/personality.h>
  47 #include <linux/binfmts.h>
  48 #include <linux/utsname.h>
  49 #include <linux/pid_namespace.h>
  50 #include <linux/module.h>
  51 #include <linux/namei.h>
  52 #include <linux/mount.h>
  53 #include <linux/security.h>
  54 #include <linux/syscalls.h>
  55 #include <linux/tsacct_kern.h>
  56 #include <linux/cn_proc.h>
  57 #include <linux/audit.h>
  58 #include <linux/kmod.h>
  59 #include <linux/fsnotify.h>
  60 #include <linux/fs_struct.h>
  61 #include <linux/oom.h>
  62 #include <linux/compat.h>
  63 #include <linux/vmalloc.h>
  64 #include <linux/io_uring.h>
  65 #include <linux/syscall_user_dispatch.h>
  66 #include <linux/coredump.h>
  67 #include <linux/time_namespace.h>
  68
  69 #include <linux/uaccess.h>
  70 #include <asm/mmu_context.h>
  71 #include <asm/tlb.h>
  72
  73 #include <trace/events/task.h>
  74 #include "internal.h"
  75
  76 #include <trace/events/sched.h>
  77
  78 static int bprm_creds_from_file(struct linux_binprm *bprm);
  79
  80 int suid_dumpable = 0;
  81
  82 static LIST_HEAD(formats);
  83 static DEFINE_RWLOCK(binfmt_lock);
  84
  85 void __register_binfmt(struct linux_binfmt * fmt, int insert)
  86 {
  87         write_lock(&binfmt_lock);
  88         insert ? list_add(&fmt->lh, &formats) :
  89                  list_add_tail(&fmt->lh, &formats);
  90         write_unlock(&binfmt_lock);
  91 }
  92
  93 EXPORT_SYMBOL(__register_binfmt);
  94
  95 void unregister_binfmt(struct linux_binfmt * fmt)
  96 {
  97         write_lock(&binfmt_lock);
  98         list_del(&fmt->lh);
  99         write_unlock(&binfmt_lock);
 100 }
 101
 102 EXPORT_SYMBOL(unregister_binfmt);
 103
 104 static inline void put_binfmt(struct linux_binfmt * fmt)
 105 {
 106         module_put(fmt->module);
 107 }
 108
 109 bool path_noexec(const struct path *path)
 110 {
 111         return (path->mnt->mnt_flags & MNT_NOEXEC) ||
 112                (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
 113 }
 114
 115 #ifdef CONFIG_USELIB
 116 /*
 117  * Note that a shared library must be both readable and executable due to
 118  * security reasons.
 119  *
 120  * Also note that we take the address to load from the file itself.
 121  */
 122 SYSCALL_DEFINE1(uselib, const char __user *, library)
 123 {
 124         struct linux_binfmt *fmt;
 125         struct file *file;
 126         struct filename *tmp = getname(library);
 127         int error = PTR_ERR(tmp);
 128         static const struct open_flags uselib_flags = {
 129                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 130                 .acc_mode = MAY_READ | MAY_EXEC,
 131                 .intent = LOOKUP_OPEN,
 132                 .lookup_flags = LOOKUP_FOLLOW,
 133         };
 134
 135         if (IS_ERR(tmp))
 136                 goto out;
 137
 138         file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
 139         putname(tmp);
 140         error = PTR_ERR(file);
 141         if (IS_ERR(file))
 142                 goto out;
 143
 144         /*
 145          * may_open() has already checked for this, so it should be
 146          * impossible to trip now. But we need to be extra cautious
 147          * and check again at the very end too.
 148          */
 149         error = -EACCES;
 150         if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
 151                          path_noexec(&file->f_path)))
 152                 goto exit;
 153
 154         fsnotify_open(file);
 155
 156         error = -ENOEXEC;
 157
 158         read_lock(&binfmt_lock);
 159         list_for_each_entry(fmt, &formats, lh) {
 160                 if (!fmt->load_shlib)
 161                         continue;
 162                 if (!try_module_get(fmt->module))
 163                         continue;
 164                 read_unlock(&binfmt_lock);
 165                 error = fmt->load_shlib(file);
 166                 read_lock(&binfmt_lock);
 167                 put_binfmt(fmt);
 168                 if (error != -ENOEXEC)
 169                         break;
 170         }
 171         read_unlock(&binfmt_lock);
 172 exit:
 173         fput(file);
 174 out:
 175         return error;
 176 }
 177 #endif /* #ifdef CONFIG_USELIB */
 178
 179 #ifdef CONFIG_MMU
 180 /*
 181  * The nascent bprm->mm is not visible until exec_mmap() but it can
 182  * use a lot of memory, account these pages in current->mm temporary
 183  * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
 184  * change the counter back via acct_arg_size(0).
 185  */
 186 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 187 {
 188         struct mm_struct *mm = current->mm;
 189         long diff = (long)(pages - bprm->vma_pages);
 190
 191         if (!mm || !diff)
 192                 return;
 193
 194         bprm->vma_pages = pages;
 195         add_mm_counter(mm, MM_ANONPAGES, diff);
 196 }
 197
 198 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 199                 int write)
 200 {
 201         struct page *page;
 202         int ret;
 203         unsigned int gup_flags = FOLL_FORCE;
 204
 205 #ifdef CONFIG_STACK_GROWSUP
 206         if (write) {
 207                 ret = expand_downwards(bprm->vma, pos);
 208                 if (ret < 0)
 209                         return NULL;
 210         }
 211 #endif
 212
 213         if (write)
 214                 gup_flags |= FOLL_WRITE;
 215
 216         /*
 217          * We are doing an exec().  'current' is the process
 218          * doing the exec and bprm->mm is the new process's mm.
 219          */
 220         mmap_read_lock(bprm->mm);
 221         ret = get_user_pages_remote(bprm->mm, pos, 1, gup_flags,
 222                         &page, NULL, NULL);
 223         mmap_read_unlock(bprm->mm);
 224         if (ret <= 0)
 225                 return NULL;
 226
 227         if (write)
 228                 acct_arg_size(bprm, vma_pages(bprm->vma));
 229
 230         return page;
 231 }
 232
 233 static void put_arg_page(struct page *page)
 234 {
 235         put_page(page);
 236 }
 237
 238 static void free_arg_pages(struct linux_binprm *bprm)
 239 {
 240 }
 241
 242 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 243                 struct page *page)
 244 {
 245         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 246 }
 247
 248 static int __bprm_mm_init(struct linux_binprm *bprm)
 249 {
 250         int err;
 251         struct vm_area_struct *vma = NULL;
 252         struct mm_struct *mm = bprm->mm;
 253
 254         bprm->vma = vma = vm_area_alloc(mm);
 255         if (!vma)
 256                 return -ENOMEM;
 257         vma_set_anonymous(vma);
 258
 259         if (mmap_write_lock_killable(mm)) {
 260                 err = -EINTR;
 261                 goto err_free;
 262         }
 263
 264         /*
 265          * Place the stack at the largest stack address the architecture
 266          * supports. Later, we'll move this to an appropriate place. We don't
 267          * use STACK_TOP because that can depend on attributes which aren't
 268          * configured yet.
 269          */
 270         BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 271         vma->vm_end = STACK_TOP_MAX;
 272         vma->vm_start = vma->vm_end - PAGE_SIZE;
 273         vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 274         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 275
 276         err = insert_vm_struct(mm, vma);
 277         if (err)
 278                 goto err;
 279
 280         mm->stack_vm = mm->total_vm = 1;
 281         mmap_write_unlock(mm);
 282         bprm->p = vma->vm_end - sizeof(void *);
 283         return 0;
 284 err:
 285         mmap_write_unlock(mm);
 286 err_free:
 287         bprm->vma = NULL;
 288         vm_area_free(vma);
 289         return err;
 290 }
 291
 292 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 293 {
 294         return len <= MAX_ARG_STRLEN;
 295 }
 296
 297 #else
 298
 299 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 300 {
 301 }
 302
 303 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 304                 int write)
 305 {
 306         struct page *page;
 307
 308         page = bprm->page[pos / PAGE_SIZE];
 309         if (!page && write) {
 310                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 311                 if (!page)
 312                         return NULL;
 313                 bprm->page[pos / PAGE_SIZE] = page;
 314         }
 315
 316         return page;
 317 }
 318
 319 static void put_arg_page(struct page *page)
 320 {
 321 }
 322
 323 static void free_arg_page(struct linux_binprm *bprm, int i)
 324 {
 325         if (bprm->page[i]) {
 326                 __free_page(bprm->page[i]);
 327                 bprm->page[i] = NULL;
 328         }
 329 }
 330
 331 static void free_arg_pages(struct linux_binprm *bprm)
 332 {
 333         int i;
 334
 335         for (i = 0; i < MAX_ARG_PAGES; i++)
 336                 free_arg_page(bprm, i);
 337 }
 338
 339 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 340                 struct page *page)
 341 {
 342 }
 343
 344 static int __bprm_mm_init(struct linux_binprm *bprm)
 345 {
 346         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 347         return 0;
 348 }
 349
 350 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 351 {
 352         return len <= bprm->p;
 353 }
 354
 355 #endif /* CONFIG_MMU */
 356
 357 /*
 358  * Create a new mm_struct and populate it with a temporary stack
 359  * vm_area_struct.  We don't have enough context at this point to set the stack
 360  * flags, permissions, and offset, so we use temporary values.  We'll update
 361  * them later in setup_arg_pages().
 362  */
 363 static int bprm_mm_init(struct linux_binprm *bprm)
 364 {
 365         int err;
 366         struct mm_struct *mm = NULL;
 367
 368         bprm->mm = mm = mm_alloc();
 369         err = -ENOMEM;
 370         if (!mm)
 371                 goto err;
 372
 373         /* Save current stack limit for all calculations made during exec. */
 374         task_lock(current->group_leader);
 375         bprm->rlim_stack = current->signal->rlim[RLIMIT_STACK];
 376         task_unlock(current->group_leader);
 377
 378         err = __bprm_mm_init(bprm);
 379         if (err)
 380                 goto err;
 381
 382         return 0;
 383
 384 err:
 385         if (mm) {
 386                 bprm->mm = NULL;
 387                 mmdrop(mm);
 388         }
 389
 390         return err;
 391 }
 392
 393 struct user_arg_ptr {
 394 #ifdef CONFIG_COMPAT
 395         bool is_compat;
 396 #endif
 397         union {
 398                 const char __user *const __user *native;
 399 #ifdef CONFIG_COMPAT
 400                 const compat_uptr_t __user *compat;
 401 #endif
 402         } ptr;
 403 };
 404
 405 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
 406 {
 407         const char __user *native;
 408
 409 #ifdef CONFIG_COMPAT
 410         if (unlikely(argv.is_compat)) {
 411                 compat_uptr_t compat;
 412
 413                 if (get_user(compat, argv.ptr.compat + nr))
 414                         return ERR_PTR(-EFAULT);
 415
 416                 return compat_ptr(compat);
 417         }
 418 #endif
 419
 420         if (get_user(native, argv.ptr.native + nr))
 421                 return ERR_PTR(-EFAULT);
 422
 423         return native;
 424 }
 425
 426 /*
 427  * count() counts the number of strings in array ARGV.
 428  */
 429 static int count(struct user_arg_ptr argv, int max)
 430 {
 431         int i = 0;
 432
 433         if (argv.ptr.native != NULL) {
 434                 for (;;) {
 435                         const char __user *p = get_user_arg_ptr(argv, i);
 436
 437                         if (!p)
 438                                 break;
 439
 440                         if (IS_ERR(p))
 441                                 return -EFAULT;
 442
 443                         if (i >= max)
 444                                 return -E2BIG;
 445                         ++i;
 446
 447                         if (fatal_signal_pending(current))
 448                                 return -ERESTARTNOHAND;
 449                         cond_resched();
 450                 }
 451         }
 452         return i;
 453 }
 454
 455 static int count_strings_kernel(const char *const *argv)
 456 {
 457         int i;
 458
 459         if (!argv)
 460                 return 0;
 461
 462         for (i = 0; argv[i]; ++i) {
 463                 if (i >= MAX_ARG_STRINGS)
 464                         return -E2BIG;
 465                 if (fatal_signal_pending(current))
 466                         return -ERESTARTNOHAND;
 467                 cond_resched();
 468         }
 469         return i;
 470 }
 471
 472 static int bprm_stack_limits(struct linux_binprm *bprm)
 473 {
 474         unsigned long limit, ptr_size;
 475
 476         /*
 477          * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
 478          * (whichever is smaller) for the argv+env strings.
 479          * This ensures that:
 480          *  - the remaining binfmt code will not run out of stack space,
 481          *  - the program will have a reasonable amount of stack left
 482          *    to work from.
 483          */
 484         limit = _STK_LIM / 4 * 3;
 485         limit = min(limit, bprm->rlim_stack.rlim_cur / 4);
 486         /*
 487          * We've historically supported up to 32 pages (ARG_MAX)
 488          * of argument strings even with small stacks
 489          */
 490         limit = max_t(unsigned long, limit, ARG_MAX);
 491         /*
 492          * We must account for the size of all the argv and envp pointers to
 493          * the argv and envp strings, since they will also take up space in
 494          * the stack. They aren't stored until much later when we can't
 495          * signal to the parent that the child has run out of stack space.
 496          * Instead, calculate it here so it's possible to fail gracefully.
 497          *
 498          * In the case of argc = 0, make sure there is space for adding a
 499          * empty string (which will bump argc to 1), to ensure confused
 500          * userspace programs don't start processing from argv[1], thinking
 501          * argc can never be 0, to keep them from walking envp by accident.
 502          * See do_execveat_common().
 503          */
 504         ptr_size = (max(bprm->argc, 1) + bprm->envc) * sizeof(void *);
 505         if (limit <= ptr_size)
 506                 return -E2BIG;
 507         limit -= ptr_size;
 508
 509         bprm->argmin = bprm->p - limit;
 510         return 0;
 511 }
 512
 513 /*
 514  * 'copy_strings()' copies argument/environment strings from the old
 515  * processes's memory to the new process's stack.  The call to get_user_pages()
 516  * ensures the destination page is created and not swapped out.
 517  */
 518 static int copy_strings(int argc, struct user_arg_ptr argv,
 519                         struct linux_binprm *bprm)
 520 {
 521         struct page *kmapped_page = NULL;
 522         char *kaddr = NULL;
 523         unsigned long kpos = 0;
 524         int ret;
 525
 526         while (argc-- > 0) {
 527                 const char __user *str;
 528                 int len;
 529                 unsigned long pos;
 530
 531                 ret = -EFAULT;
 532                 str = get_user_arg_ptr(argv, argc);
 533                 if (IS_ERR(str))
 534                         goto out;
 535
 536                 len = strnlen_user(str, MAX_ARG_STRLEN);
 537                 if (!len)
 538                         goto out;
 539
 540                 ret = -E2BIG;
 541                 if (!valid_arg_len(bprm, len))
 542                         goto out;
 543
 544                 /* We're going to work our way backwards. */
 545                 pos = bprm->p;
 546                 str += len;
 547                 bprm->p -= len;
 548 #ifdef CONFIG_MMU
 549                 if (bprm->p < bprm->argmin)
 550                         goto out;
 551 #endif
 552
 553                 while (len > 0) {
 554                         int offset, bytes_to_copy;
 555
 556                         if (fatal_signal_pending(current)) {
 557                                 ret = -ERESTARTNOHAND;
 558                                 goto out;
 559                         }
 560                         cond_resched();
 561
 562                         offset = pos % PAGE_SIZE;
 563                         if (offset == 0)
 564                                 offset = PAGE_SIZE;
 565
 566                         bytes_to_copy = offset;
 567                         if (bytes_to_copy > len)
 568                                 bytes_to_copy = len;
 569
 570                         offset -= bytes_to_copy;
 571                         pos -= bytes_to_copy;
 572                         str -= bytes_to_copy;
 573                         len -= bytes_to_copy;
 574
 575                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 576                                 struct page *page;
 577
 578                                 page = get_arg_page(bprm, pos, 1);
 579                                 if (!page) {
 580                                         ret = -E2BIG;
 581                                         goto out;
 582                                 }
 583
 584                                 if (kmapped_page) {
 585                                         flush_dcache_page(kmapped_page);
 586                                         kunmap_local(kaddr);
 587                                         put_arg_page(kmapped_page);
 588                                 }
 589                                 kmapped_page = page;
 590                                 kaddr = kmap_local_page(kmapped_page);
 591                                 kpos = pos & PAGE_MASK;
 592                                 flush_arg_page(bprm, kpos, kmapped_page);
 593                         }
 594                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 595                                 ret = -EFAULT;
 596                                 goto out;
 597                         }
 598                 }
 599         }
 600         ret = 0;
 601 out:
 602         if (kmapped_page) {
 603                 flush_dcache_page(kmapped_page);
 604                 kunmap_local(kaddr);
 605                 put_arg_page(kmapped_page);
 606         }
 607         return ret;
 608 }
 609
 610 /*
 611  * Copy and argument/environment string from the kernel to the processes stack.
 612  */
 613 int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
 614 {
 615         int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */;
 616         unsigned long pos = bprm->p;
 617
 618         if (len == 0)
 619                 return -EFAULT;
 620         if (!valid_arg_len(bprm, len))
 621                 return -E2BIG;
 622
 623         /* We're going to work our way backwards. */
 624         arg += len;
 625         bprm->p -= len;
 626         if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin)
 627                 return -E2BIG;
 628
 629         while (len > 0) {
 630                 unsigned int bytes_to_copy = min_t(unsigned int, len,
 631                                 min_not_zero(offset_in_page(pos), PAGE_SIZE));
 632                 struct page *page;
 633
 634                 pos -= bytes_to_copy;
 635                 arg -= bytes_to_copy;
 636                 len -= bytes_to_copy;
 637
 638                 page = get_arg_page(bprm, pos, 1);
 639                 if (!page)
 640                         return -E2BIG;
 641                 flush_arg_page(bprm, pos & PAGE_MASK, page);
 642                 memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy);
 643                 put_arg_page(page);
 644         }
 645
 646         return 0;
 647 }
 648 EXPORT_SYMBOL(copy_string_kernel);
 649
 650 static int copy_strings_kernel(int argc, const char *const *argv,
 651                                struct linux_binprm *bprm)
 652 {
 653         while (argc-- > 0) {
 654                 int ret = copy_string_kernel(argv[argc], bprm);
 655                 if (ret < 0)
 656                         return ret;
 657                 if (fatal_signal_pending(current))
 658                         return -ERESTARTNOHAND;
 659                 cond_resched();
 660         }
 661         return 0;
 662 }
 663
 664 #ifdef CONFIG_MMU
 665
 666 /*
 667  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 668  * the binfmt code determines where the new stack should reside, we shift it to
 669  * its final location.  The process proceeds as follows:
 670  *
 671  * 1) Use shift to calculate the new vma endpoints.
 672  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 673  *    arguments passed to subsequent functions are consistent.
 674  * 3) Move vma's page tables to the new range.
 675  * 4) Free up any cleared pgd range.
 676  * 5) Shrink the vma to cover only the new range.
 677  */
 678 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 679 {
 680         struct mm_struct *mm = vma->vm_mm;
 681         unsigned long old_start = vma->vm_start;
 682         unsigned long old_end = vma->vm_end;
 683         unsigned long length = old_end - old_start;
 684         unsigned long new_start = old_start - shift;
 685         unsigned long new_end = old_end - shift;
 686         VMA_ITERATOR(vmi, mm, new_start);
 687         struct vm_area_struct *next;
 688         struct mmu_gather tlb;
 689
 690         BUG_ON(new_start > new_end);
 691
 692         /*
 693          * ensure there are no vmas between where we want to go
 694          * and where we are
 695          */
 696         if (vma != vma_next(&vmi))
 697                 return -EFAULT;
 698
 699         /*
 700          * cover the whole range: [new_start, old_end)
 701          */
 702         if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 703                 return -ENOMEM;
 704
 705         /*
 706          * move the page tables downwards, on failure we rely on
 707          * process cleanup to remove whatever mess we made.
 708          */
 709         if (length != move_page_tables(vma, old_start,
 710                                        vma, new_start, length, false))
 711                 return -ENOMEM;
 712
 713         lru_add_drain();
 714         tlb_gather_mmu(&tlb, mm);
 715         next = vma_next(&vmi);
 716         if (new_end > old_start) {
 717                 /*
 718                  * when the old and new regions overlap clear from new_end.
 719                  */
 720                 free_pgd_range(&tlb, new_end, old_end, new_end,
 721                         next ? next->vm_start : USER_PGTABLES_CEILING);
 722         } else {
 723                 /*
 724                  * otherwise, clean from old_start; this is done to not touch
 725                  * the address space in [new_end, old_start) some architectures
 726                  * have constraints on va-space that make this illegal (IA64) -
 727                  * for the others its just a little faster.
 728                  */
 729                 free_pgd_range(&tlb, old_start, old_end, new_end,
 730                         next ? next->vm_start : USER_PGTABLES_CEILING);
 731         }
 732         tlb_finish_mmu(&tlb);
 733
 734         /*
 735          * Shrink the vma to just the new range.  Always succeeds.
 736          */
 737         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 738
 739         return 0;
 740 }
 741
 742 /*
 743  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 744  * the stack is optionally relocated, and some extra space is added.
 745  */
 746 int setup_arg_pages(struct linux_binprm *bprm,
 747                     unsigned long stack_top,
 748                     int executable_stack)
 749 {
 750         unsigned long ret;
 751         unsigned long stack_shift;
 752         struct mm_struct *mm = current->mm;
 753         struct vm_area_struct *vma = bprm->vma;
 754         struct vm_area_struct *prev = NULL;
 755         unsigned long vm_flags;
 756         unsigned long stack_base;
 757         unsigned long stack_size;
 758         unsigned long stack_expand;
 759         unsigned long rlim_stack;
 760         struct mmu_gather tlb;
 761
 762 #ifdef CONFIG_STACK_GROWSUP
 763         /* Limit stack size */
 764         stack_base = bprm->rlim_stack.rlim_max;
 765
 766         stack_base = calc_max_stack_size(stack_base);
 767
 768         /* Add space for stack randomization. */
 769         stack_base += (STACK_RND_MASK << PAGE_SHIFT);
 770
 771         /* Make sure we didn't let the argument array grow too large. */
 772         if (vma->vm_end - vma->vm_start > stack_base)
 773                 return -ENOMEM;
 774
 775         stack_base = PAGE_ALIGN(stack_top - stack_base);
 776
 777         stack_shift = vma->vm_start - stack_base;
 778         mm->arg_start = bprm->p - stack_shift;
 779         bprm->p = vma->vm_end - stack_shift;
 780 #else
 781         stack_top = arch_align_stack(stack_top);
 782         stack_top = PAGE_ALIGN(stack_top);
 783
 784         if (unlikely(stack_top < mmap_min_addr) ||
 785             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 786                 return -ENOMEM;
 787
 788         stack_shift = vma->vm_end - stack_top;
 789
 790         bprm->p -= stack_shift;
 791         mm->arg_start = bprm->p;
 792 #endif
 793
 794         if (bprm->loader)
 795                 bprm->loader -= stack_shift;
 796         bprm->exec -= stack_shift;
 797
 798         if (mmap_write_lock_killable(mm))
 799                 return -EINTR;
 800
 801         vm_flags = VM_STACK_FLAGS;
 802
 803         /*
 804          * Adjust stack execute permissions; explicitly enable for
 805          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 806          * (arch default) otherwise.
 807          */
 808         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 809                 vm_flags |= VM_EXEC;
 810         else if (executable_stack == EXSTACK_DISABLE_X)
 811                 vm_flags &= ~VM_EXEC;
 812         vm_flags |= mm->def_flags;
 813         vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 814
 815         tlb_gather_mmu(&tlb, mm);
 816         ret = mprotect_fixup(&tlb, vma, &prev, vma->vm_start, vma->vm_end,
 817                         vm_flags);
 818         tlb_finish_mmu(&tlb);
 819
 820         if (ret)
 821                 goto out_unlock;
 822         BUG_ON(prev != vma);
 823
 824         if (unlikely(vm_flags & VM_EXEC)) {
 825                 pr_warn_once("process '%pD4' started with executable stack\n",
 826                              bprm->file);
 827         }
 828
 829         /* Move stack pages down in memory. */
 830         if (stack_shift) {
 831                 ret = shift_arg_pages(vma, stack_shift);
 832                 if (ret)
 833                         goto out_unlock;
 834         }
 835
 836         /* mprotect_fixup is overkill to remove the temporary stack flags */
 837         vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 838
 839         stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 840         stack_size = vma->vm_end - vma->vm_start;
 841         /*
 842          * Align this down to a page boundary as expand_stack
 843          * will align it up.
 844          */
 845         rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK;
 846 #ifdef CONFIG_STACK_GROWSUP
 847         if (stack_size + stack_expand > rlim_stack)
 848                 stack_base = vma->vm_start + rlim_stack;
 849         else
 850                 stack_base = vma->vm_end + stack_expand;
 851 #else
 852         if (stack_size + stack_expand > rlim_stack)
 853                 stack_base = vma->vm_end - rlim_stack;
 854         else
 855                 stack_base = vma->vm_start - stack_expand;
 856 #endif
 857         current->mm->start_stack = bprm->p;
 858         ret = expand_stack(vma, stack_base);
 859         if (ret)
 860                 ret = -EFAULT;
 861
 862 out_unlock:
 863         mmap_write_unlock(mm);
 864         return ret;
 865 }
 866 EXPORT_SYMBOL(setup_arg_pages);
 867
 868 #else
 869
 870 /*
 871  * Transfer the program arguments and environment from the holding pages
 872  * onto the stack. The provided stack pointer is adjusted accordingly.
 873  */
 874 int transfer_args_to_stack(struct linux_binprm *bprm,
 875                            unsigned long *sp_location)
 876 {
 877         unsigned long index, stop, sp;
 878         int ret = 0;
 879
 880         stop = bprm->p >> PAGE_SHIFT;
 881         sp = *sp_location;
 882
 883         for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
 884                 unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
 885                 char *src = kmap_local_page(bprm->page[index]) + offset;
 886                 sp -= PAGE_SIZE - offset;
 887                 if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
 888                         ret = -EFAULT;
 889                 kunmap_local(src);
 890                 if (ret)
 891                         goto out;
 892         }
 893
 894         *sp_location = sp;
 895
 896 out:
 897         return ret;
 898 }
 899 EXPORT_SYMBOL(transfer_args_to_stack);
 900
 901 #endif /* CONFIG_MMU */
 902
 903 static struct file *do_open_execat(int fd, struct filename *name, int flags)
 904 {
 905         struct file *file;
 906         int err;
 907         struct open_flags open_exec_flags = {
 908                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 909                 .acc_mode = MAY_EXEC,
 910                 .intent = LOOKUP_OPEN,
 911                 .lookup_flags = LOOKUP_FOLLOW,
 912         };
 913
 914         if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 915                 return ERR_PTR(-EINVAL);
 916         if (flags & AT_SYMLINK_NOFOLLOW)
 917                 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
 918         if (flags & AT_EMPTY_PATH)
 919                 open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
 920
 921         file = do_filp_open(fd, name, &open_exec_flags);
 922         if (IS_ERR(file))
 923                 goto out;
 924
 925         /*
 926          * may_open() has already checked for this, so it should be
 927          * impossible to trip now. But we need to be extra cautious
 928          * and check again at the very end too.
 929          */
 930         err = -EACCES;
 931         if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
 932                          path_noexec(&file->f_path)))
 933                 goto exit;
 934
 935         err = deny_write_access(file);
 936         if (err)
 937                 goto exit;
 938
 939         if (name->name[0] != '\0')
 940                 fsnotify_open(file);
 941
 942 out:
 943         return file;
 944
 945 exit:
 946         fput(file);
 947         return ERR_PTR(err);
 948 }
 949
 950 struct file *open_exec(const char *name)
 951 {
 952         struct filename *filename = getname_kernel(name);
 953         struct file *f = ERR_CAST(filename);
 954
 955         if (!IS_ERR(filename)) {
 956                 f = do_open_execat(AT_FDCWD, filename, 0);
 957                 putname(filename);
 958         }
 959         return f;
 960 }
 961 EXPORT_SYMBOL(open_exec);
 962
 963 #if defined(CONFIG_HAVE_AOUT) || defined(CONFIG_BINFMT_FLAT) || \
 964     defined(CONFIG_BINFMT_ELF_FDPIC)
 965 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
 966 {
 967         ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
 968         if (res > 0)
 969                 flush_icache_user_range(addr, addr + len);
 970         return res;
 971 }
 972 EXPORT_SYMBOL(read_code);
 973 #endif
 974
 975 /*
 976  * Maps the mm_struct mm into the current task struct.
 977  * On success, this function returns with exec_update_lock
 978  * held for writing.
 979  */
 980 static int exec_mmap(struct mm_struct *mm)
 981 {
 982         struct task_struct *tsk;
 983         struct mm_struct *old_mm, *active_mm;
 984         bool vfork;
 985         int ret;
 986
 987         /* Notify parent that we're no longer interested in the old VM */
 988         tsk = current;
 989         vfork = !!tsk->vfork_done;
 990         old_mm = current->mm;
 991         exec_mm_release(tsk, old_mm);
 992         if (old_mm)
 993                 sync_mm_rss(old_mm);
 994
 995         ret = down_write_killable(&tsk->signal->exec_update_lock);
 996         if (ret)
 997                 return ret;
 998
 999         if (old_mm) {
1000                 /*
1001                  * If there is a pending fatal signal perhaps a signal
1002                  * whose default action is to create a coredump get
1003                  * out and die instead of going through with the exec.
1004                  */
1005                 ret = mmap_read_lock_killable(old_mm);
1006                 if (ret) {
1007                         up_write(&tsk->signal->exec_update_lock);
1008                         return ret;
1009                 }
1010         }
1011
1012         task_lock(tsk);
1013         membarrier_exec_mmap(mm);
1014
1015         local_irq_disable();
1016         active_mm = tsk->active_mm;
1017         tsk->active_mm = mm;
1018         tsk->mm = mm;
1019         lru_gen_add_mm(mm);
1020         /*
1021          * This prevents preemption while active_mm is being loaded and
1022          * it and mm are being updated, which could cause problems for
1023          * lazy tlb mm refcounting when these are updated by context
1024          * switches. Not all architectures can handle irqs off over
1025          * activate_mm yet.
1026          */
1027         if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1028                 local_irq_enable();
1029         activate_mm(active_mm, mm);
1030         if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1031                 local_irq_enable();
1032         task_unlock(tsk);
1033         lru_gen_use_mm(mm);
1034
1035         if (vfork)
1036                 timens_on_fork(tsk->nsproxy, tsk);
1037
1038         if (old_mm) {
1039                 mmap_read_unlock(old_mm);
1040                 BUG_ON(active_mm != old_mm);
1041                 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
1042                 mm_update_next_owner(old_mm);
1043                 mmput(old_mm);
1044                 return 0;
1045         }
1046         mmdrop(active_mm);
1047         return 0;
1048 }
1049
1050 static int de_thread(struct task_struct *tsk)
1051 {
1052         struct signal_struct *sig = tsk->signal;
1053         struct sighand_struct *oldsighand = tsk->sighand;
1054         spinlock_t *lock = &oldsighand->siglock;
1055
1056         if (thread_group_empty(tsk))
1057                 goto no_thread_group;
1058
1059         /*
1060          * Kill all other threads in the thread group.
1061          */
1062         spin_lock_irq(lock);
1063         if ((sig->flags & SIGNAL_GROUP_EXIT) || sig->group_exec_task) {
1064                 /*
1065                  * Another group action in progress, just
1066                  * return so that the signal is processed.
1067                  */
1068                 spin_unlock_irq(lock);
1069                 return -EAGAIN;
1070         }
1071
1072         sig->group_exec_task = tsk;
1073         sig->notify_count = zap_other_threads(tsk);
1074         if (!thread_group_leader(tsk))
1075                 sig->notify_count--;
1076
1077         while (sig->notify_count) {
1078                 __set_current_state(TASK_KILLABLE);
1079                 spin_unlock_irq(lock);
1080                 schedule();
1081                 if (__fatal_signal_pending(tsk))
1082                         goto killed;
1083                 spin_lock_irq(lock);
1084         }
1085         spin_unlock_irq(lock);
1086
1087         /*
1088          * At this point all other threads have exited, all we have to
1089          * do is to wait for the thread group leader to become inactive,
1090          * and to assume its PID:
1091          */
1092         if (!thread_group_leader(tsk)) {
1093                 struct task_struct *leader = tsk->group_leader;
1094
1095                 for (;;) {
1096                         cgroup_threadgroup_change_begin(tsk);
1097                         write_lock_irq(&tasklist_lock);
1098                         /*
1099                          * Do this under tasklist_lock to ensure that
1100                          * exit_notify() can't miss ->group_exec_task
1101                          */
1102                         sig->notify_count = -1;
1103                         if (likely(leader->exit_state))
1104                                 break;
1105                         __set_current_state(TASK_KILLABLE);
1106                         write_unlock_irq(&tasklist_lock);
1107                         cgroup_threadgroup_change_end(tsk);
1108                         schedule();
1109                         if (__fatal_signal_pending(tsk))
1110                                 goto killed;
1111                 }
1112
1113                 /*
1114                  * The only record we have of the real-time age of a
1115                  * process, regardless of execs it's done, is start_time.
1116                  * All the past CPU time is accumulated in signal_struct
1117                  * from sister threads now dead.  But in this non-leader
1118                  * exec, nothing survives from the original leader thread,
1119                  * whose birth marks the true age of this process now.
1120                  * When we take on its identity by switching to its PID, we
1121                  * also take its birthdate (always earlier than our own).
1122                  */
1123                 tsk->start_time = leader->start_time;
1124                 tsk->start_boottime = leader->start_boottime;
1125
1126                 BUG_ON(!same_thread_group(leader, tsk));
1127                 /*
1128                  * An exec() starts a new thread group with the
1129                  * TGID of the previous thread group. Rehash the
1130                  * two threads with a switched PID, and release
1131                  * the former thread group leader:
1132                  */
1133
1134                 /* Become a process group leader with the old leader's pid.
1135                  * The old leader becomes a thread of the this thread group.
1136                  */
1137                 exchange_tids(tsk, leader);
1138                 transfer_pid(leader, tsk, PIDTYPE_TGID);
1139                 transfer_pid(leader, tsk, PIDTYPE_PGID);
1140                 transfer_pid(leader, tsk, PIDTYPE_SID);
1141
1142                 list_replace_rcu(&leader->tasks, &tsk->tasks);
1143                 list_replace_init(&leader->sibling, &tsk->sibling);
1144
1145                 tsk->group_leader = tsk;
1146                 leader->group_leader = tsk;
1147
1148                 tsk->exit_signal = SIGCHLD;
1149                 leader->exit_signal = -1;
1150
1151                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1152                 leader->exit_state = EXIT_DEAD;
1153
1154                 /*
1155                  * We are going to release_task()->ptrace_unlink() silently,
1156                  * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1157                  * the tracer won't block again waiting for this thread.
1158                  */
1159                 if (unlikely(leader->ptrace))
1160                         __wake_up_parent(leader, leader->parent);
1161                 write_unlock_irq(&tasklist_lock);
1162                 cgroup_threadgroup_change_end(tsk);
1163
1164                 release_task(leader);
1165         }
1166
1167         sig->group_exec_task = NULL;
1168         sig->notify_count = 0;
1169
1170 no_thread_group:
1171         /* we have changed execution domain */
1172         tsk->exit_signal = SIGCHLD;
1173
1174         BUG_ON(!thread_group_leader(tsk));
1175         return 0;
1176
1177 killed:
1178         /* protects against exit_notify() and __exit_signal() */
1179         read_lock(&tasklist_lock);
1180         sig->group_exec_task = NULL;
1181         sig->notify_count = 0;
1182         read_unlock(&tasklist_lock);
1183         return -EAGAIN;
1184 }
1185
1186
1187 /*
1188  * This function makes sure the current process has its own signal table,
1189  * so that flush_signal_handlers can later reset the handlers without
1190  * disturbing other processes.  (Other processes might share the signal
1191  * table via the CLONE_SIGHAND option to clone().)
1192  */
1193 static int unshare_sighand(struct task_struct *me)
1194 {
1195         struct sighand_struct *oldsighand = me->sighand;
1196
1197         if (refcount_read(&oldsighand->count) != 1) {
1198                 struct sighand_struct *newsighand;
1199                 /*
1200                  * This ->sighand is shared with the CLONE_SIGHAND
1201                  * but not CLONE_THREAD task, switch to the new one.
1202                  */
1203                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1204                 if (!newsighand)
1205                         return -ENOMEM;
1206
1207                 refcount_set(&newsighand->count, 1);
1208                 memcpy(newsighand->action, oldsighand->action,
1209                        sizeof(newsighand->action));
1210
1211                 write_lock_irq(&tasklist_lock);
1212                 spin_lock(&oldsighand->siglock);
1213                 rcu_assign_pointer(me->sighand, newsighand);
1214                 spin_unlock(&oldsighand->siglock);
1215                 write_unlock_irq(&tasklist_lock);
1216
1217                 __cleanup_sighand(oldsighand);
1218         }
1219         return 0;
1220 }
1221
1222 char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
1223 {
1224         task_lock(tsk);
1225         /* Always NUL terminated and zero-padded */
1226         strscpy_pad(buf, tsk->comm, buf_size);
1227         task_unlock(tsk);
1228         return buf;
1229 }
1230 EXPORT_SYMBOL_GPL(__get_task_comm);
1231
1232 /*
1233  * These functions flushes out all traces of the currently running executable
1234  * so that a new one can be started
1235  */
1236
1237 void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1238 {
1239         task_lock(tsk);
1240         trace_task_rename(tsk, buf);
1241         strscpy_pad(tsk->comm, buf, sizeof(tsk->comm));
1242         task_unlock(tsk);
1243         perf_event_comm(tsk, exec);
1244 }
1245
1246 /*
1247  * Calling this is the point of no return. None of the failures will be
1248  * seen by userspace since either the process is already taking a fatal
1249  * signal (via de_thread() or coredump), or will have SEGV raised
1250  * (after exec_mmap()) by search_binary_handler (see below).
1251  */
1252 int begin_new_exec(struct linux_binprm * bprm)
1253 {
1254         struct task_struct *me = current;
1255         int retval;
1256
1257         /* Once we are committed compute the creds */
1258         retval = bprm_creds_from_file(bprm);
1259         if (retval)
1260                 return retval;
1261
1262         /*
1263          * Ensure all future errors are fatal.
1264          */
1265         bprm->point_of_no_return = true;
1266
1267         /*
1268          * Make this the only thread in the thread group.
1269          */
1270         retval = de_thread(me);
1271         if (retval)
1272                 goto out;
1273
1274         /*
1275          * Cancel any io_uring activity across execve
1276          */
1277         io_uring_task_cancel();
1278
1279         /* Ensure the files table is not shared. */
1280         retval = unshare_files();
1281         if (retval)
1282                 goto out;
1283
1284         /*
1285          * Must be called _before_ exec_mmap() as bprm->mm is
1286          * not visible until then. This also enables the update
1287          * to be lockless.
1288          */
1289         retval = set_mm_exe_file(bprm->mm, bprm->file);
1290         if (retval)
1291                 goto out;
1292
1293         /* If the binary is not readable then enforce mm->dumpable=0 */
1294         would_dump(bprm, bprm->file);
1295         if (bprm->have_execfd)
1296                 would_dump(bprm, bprm->executable);
1297
1298         /*
1299          * Release all of the old mmap stuff
1300          */
1301         acct_arg_size(bprm, 0);
1302         retval = exec_mmap(bprm->mm);
1303         if (retval)
1304                 goto out;
1305
1306         bprm->mm = NULL;
1307
1308 #ifdef CONFIG_POSIX_TIMERS
1309         spin_lock_irq(&me->sighand->siglock);
1310         posix_cpu_timers_exit(me);
1311         spin_unlock_irq(&me->sighand->siglock);
1312         exit_itimers(me);
1313         flush_itimer_signals();
1314 #endif
1315
1316         /*
1317          * Make the signal table private.
1318          */
1319         retval = unshare_sighand(me);
1320         if (retval)
1321                 goto out_unlock;
1322
1323         me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC |
1324                                         PF_NOFREEZE | PF_NO_SETAFFINITY);
1325         flush_thread();
1326         me->personality &= ~bprm->per_clear;
1327
1328         clear_syscall_work_syscall_user_dispatch(me);
1329
1330         /*
1331          * We have to apply CLOEXEC before we change whether the process is
1332          * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1333          * trying to access the should-be-closed file descriptors of a process
1334          * undergoing exec(2).
1335          */
1336         do_close_on_exec(me->files);
1337
1338         if (bprm->secureexec) {
1339                 /* Make sure parent cannot signal privileged process. */
1340                 me->pdeath_signal = 0;
1341
1342                 /*
1343                  * For secureexec, reset the stack limit to sane default to
1344                  * avoid bad behavior from the prior rlimits. This has to
1345                  * happen before arch_pick_mmap_layout(), which examines
1346                  * RLIMIT_STACK, but after the point of no return to avoid
1347                  * needing to clean up the change on failure.
1348                  */
1349                 if (bprm->rlim_stack.rlim_cur > _STK_LIM)
1350                         bprm->rlim_stack.rlim_cur = _STK_LIM;
1351         }
1352
1353         me->sas_ss_sp = me->sas_ss_size = 0;
1354
1355         /*
1356          * Figure out dumpability. Note that this checking only of current
1357          * is wrong, but userspace depends on it. This should be testing
1358          * bprm->secureexec instead.
1359          */
1360         if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
1361             !(uid_eq(current_euid(), current_uid()) &&
1362               gid_eq(current_egid(), current_gid())))
1363                 set_dumpable(current->mm, suid_dumpable);
1364         else
1365                 set_dumpable(current->mm, SUID_DUMP_USER);
1366
1367         perf_event_exec();
1368         __set_task_comm(me, kbasename(bprm->filename), true);
1369
1370         /* An exec changes our domain. We are no longer part of the thread
1371            group */
1372         WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
1373         flush_signal_handlers(me, 0);
1374
1375         retval = set_cred_ucounts(bprm->cred);
1376         if (retval < 0)
1377                 goto out_unlock;
1378
1379         /*
1380          * install the new credentials for this executable
1381          */
1382         security_bprm_committing_creds(bprm);
1383
1384         commit_creds(bprm->cred);
1385         bprm->cred = NULL;
1386
1387         /*
1388          * Disable monitoring for regular users
1389          * when executing setuid binaries. Must
1390          * wait until new credentials are committed
1391          * by commit_creds() above
1392          */
1393         if (get_dumpable(me->mm) != SUID_DUMP_USER)
1394                 perf_event_exit_task(me);
1395         /*
1396          * cred_guard_mutex must be held at least to this point to prevent
1397          * ptrace_attach() from altering our determination of the task's
1398          * credentials; any time after this it may be unlocked.
1399          */
1400         security_bprm_committed_creds(bprm);
1401
1402         /* Pass the opened binary to the interpreter. */
1403         if (bprm->have_execfd) {
1404                 retval = get_unused_fd_flags(0);
1405                 if (retval < 0)
1406                         goto out_unlock;
1407                 fd_install(retval, bprm->executable);
1408                 bprm->executable = NULL;
1409                 bprm->execfd = retval;
1410         }
1411         return 0;
1412
1413 out_unlock:
1414         up_write(&me->signal->exec_update_lock);
1415 out:
1416         return retval;
1417 }
1418 EXPORT_SYMBOL(begin_new_exec);
1419
1420 void would_dump(struct linux_binprm *bprm, struct file *file)
1421 {
1422         struct inode *inode = file_inode(file);
1423         struct user_namespace *mnt_userns = file_mnt_user_ns(file);
1424         if (inode_permission(mnt_userns, inode, MAY_READ) < 0) {
1425                 struct user_namespace *old, *user_ns;
1426                 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1427
1428                 /* Ensure mm->user_ns contains the executable */
1429                 user_ns = old = bprm->mm->user_ns;
1430                 while ((user_ns != &init_user_ns) &&
1431                        !privileged_wrt_inode_uidgid(user_ns, mnt_userns, inode))
1432                         user_ns = user_ns->parent;
1433
1434                 if (old != user_ns) {
1435                         bprm->mm->user_ns = get_user_ns(user_ns);
1436                         put_user_ns(old);
1437                 }
1438         }
1439 }
1440 EXPORT_SYMBOL(would_dump);
1441
1442 void setup_new_exec(struct linux_binprm * bprm)
1443 {
1444         /* Setup things that can depend upon the personality */
1445         struct task_struct *me = current;
1446
1447         arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
1448
1449         arch_setup_new_exec();
1450
1451         /* Set the new mm task size. We have to do that late because it may
1452          * depend on TIF_32BIT which is only updated in flush_thread() on
1453          * some architectures like powerpc
1454          */
1455         me->mm->task_size = TASK_SIZE;
1456         up_write(&me->signal->exec_update_lock);
1457         mutex_unlock(&me->signal->cred_guard_mutex);
1458 }
1459 EXPORT_SYMBOL(setup_new_exec);
1460
1461 /* Runs immediately before start_thread() takes over. */
1462 void finalize_exec(struct linux_binprm *bprm)
1463 {
1464         /* Store any stack rlimit changes before starting thread. */
1465         task_lock(current->group_leader);
1466         current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack;
1467         task_unlock(current->group_leader);
1468 }
1469 EXPORT_SYMBOL(finalize_exec);
1470
1471 /*
1472  * Prepare credentials and lock ->cred_guard_mutex.
1473  * setup_new_exec() commits the new creds and drops the lock.
1474  * Or, if exec fails before, free_bprm() should release ->cred
1475  * and unlock.
1476  */
1477 static int prepare_bprm_creds(struct linux_binprm *bprm)
1478 {
1479         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1480                 return -ERESTARTNOINTR;
1481
1482         bprm->cred = prepare_exec_creds();
1483         if (likely(bprm->cred))
1484                 return 0;
1485
1486         mutex_unlock(&current->signal->cred_guard_mutex);
1487         return -ENOMEM;
1488 }
1489
1490 static void free_bprm(struct linux_binprm *bprm)
1491 {
1492         if (bprm->mm) {
1493                 acct_arg_size(bprm, 0);
1494                 mmput(bprm->mm);
1495         }
1496         free_arg_pages(bprm);
1497         if (bprm->cred) {
1498                 mutex_unlock(&current->signal->cred_guard_mutex);
1499                 abort_creds(bprm->cred);
1500         }
1501         if (bprm->file) {
1502                 allow_write_access(bprm->file);
1503                 fput(bprm->file);
1504         }
1505         if (bprm->executable)
1506                 fput(bprm->executable);
1507         /* If a binfmt changed the interp, free it. */
1508         if (bprm->interp != bprm->filename)
1509                 kfree(bprm->interp);
1510         kfree(bprm->fdpath);
1511         kfree(bprm);
1512 }
1513
1514 static struct linux_binprm *alloc_bprm(int fd, struct filename *filename)
1515 {
1516         struct linux_binprm *bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1517         int retval = -ENOMEM;
1518         if (!bprm)
1519                 goto out;
1520
1521         if (fd == AT_FDCWD || filename->name[0] == '/') {
1522                 bprm->filename = filename->name;
1523         } else {
1524                 if (filename->name[0] == '\0')
1525                         bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd);
1526                 else
1527                         bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s",
1528                                                   fd, filename->name);
1529                 if (!bprm->fdpath)
1530                         goto out_free;
1531
1532                 bprm->filename = bprm->fdpath;
1533         }
1534         bprm->interp = bprm->filename;
1535
1536         retval = bprm_mm_init(bprm);
1537         if (retval)
1538                 goto out_free;
1539         return bprm;
1540
1541 out_free:
1542         free_bprm(bprm);
1543 out:
1544         return ERR_PTR(retval);
1545 }
1546
1547 int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
1548 {
1549         /* If a binfmt changed the interp, free it first. */
1550         if (bprm->interp != bprm->filename)
1551                 kfree(bprm->interp);
1552         bprm->interp = kstrdup(interp, GFP_KERNEL);
1553         if (!bprm->interp)
1554                 return -ENOMEM;
1555         return 0;
1556 }
1557 EXPORT_SYMBOL(bprm_change_interp);
1558
1559 /*
1560  * determine how safe it is to execute the proposed program
1561  * - the caller must hold ->cred_guard_mutex to protect against
1562  *   PTRACE_ATTACH or seccomp thread-sync
1563  */
1564 static void check_unsafe_exec(struct linux_binprm *bprm)
1565 {
1566         struct task_struct *p = current, *t;
1567         unsigned n_fs;
1568
1569         if (p->ptrace)
1570                 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1571
1572         /*
1573          * This isn't strictly necessary, but it makes it harder for LSMs to
1574          * mess up.
1575          */
1576         if (task_no_new_privs(current))
1577                 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1578
1579         t = p;
1580         n_fs = 1;
1581         spin_lock(&p->fs->lock);
1582         rcu_read_lock();
1583         while_each_thread(p, t) {
1584                 if (t->fs == p->fs)
1585                         n_fs++;
1586         }
1587         rcu_read_unlock();
1588
1589         if (p->fs->users > n_fs)
1590                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1591         else
1592                 p->fs->in_exec = 1;
1593         spin_unlock(&p->fs->lock);
1594 }
1595
1596 static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
1597 {
1598         /* Handle suid and sgid on files */
1599         struct user_namespace *mnt_userns;
1600         struct inode *inode;
1601         unsigned int mode;
1602         kuid_t uid;
1603         kgid_t gid;
1604
1605         if (!mnt_may_suid(file->f_path.mnt))
1606                 return;
1607
1608         if (task_no_new_privs(current))
1609                 return;
1610
1611         inode = file->f_path.dentry->d_inode;
1612         mode = READ_ONCE(inode->i_mode);
1613         if (!(mode & (S_ISUID|S_ISGID)))
1614                 return;
1615
1616         mnt_userns = file_mnt_user_ns(file);
1617
1618         /* Be careful if suid/sgid is set */
1619         inode_lock(inode);
1620
1621         /* reload atomically mode/uid/gid now that lock held */
1622         mode = inode->i_mode;
1623         uid = i_uid_into_mnt(mnt_userns, inode);
1624         gid = i_gid_into_mnt(mnt_userns, inode);
1625         inode_unlock(inode);
1626
1627         /* We ignore suid/sgid if there are no mappings for them in the ns */
1628         if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
1629                  !kgid_has_mapping(bprm->cred->user_ns, gid))
1630                 return;
1631
1632         if (mode & S_ISUID) {
1633                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1634                 bprm->cred->euid = uid;
1635         }
1636
1637         if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1638                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1639                 bprm->cred->egid = gid;
1640         }
1641 }
1642
1643 /*
1644  * Compute brpm->cred based upon the final binary.
1645  */
1646 static int bprm_creds_from_file(struct linux_binprm *bprm)
1647 {
1648         /* Compute creds based on which file? */
1649         struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file;
1650
1651         bprm_fill_uid(bprm, file);
1652         return security_bprm_creds_from_file(bprm, file);
1653 }
1654
1655 /*
1656  * Fill the binprm structure from the inode.
1657  * Read the first BINPRM_BUF_SIZE bytes
1658  *
1659  * This may be called multiple times for binary chains (scripts for example).
1660  */
1661 static int prepare_binprm(struct linux_binprm *bprm)
1662 {
1663         loff_t pos = 0;
1664
1665         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1666         return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
1667 }
1668
1669 /*
1670  * Arguments are '\0' separated strings found at the location bprm->p
1671  * points to; chop off the first by relocating brpm->p to right after
1672  * the first '\0' encountered.
1673  */
1674 int remove_arg_zero(struct linux_binprm *bprm)
1675 {
1676         int ret = 0;
1677         unsigned long offset;
1678         char *kaddr;
1679         struct page *page;
1680
1681         if (!bprm->argc)
1682                 return 0;
1683
1684         do {
1685                 offset = bprm->p & ~PAGE_MASK;
1686                 page = get_arg_page(bprm, bprm->p, 0);
1687                 if (!page) {
1688                         ret = -EFAULT;
1689                         goto out;
1690                 }
1691                 kaddr = kmap_local_page(page);
1692
1693                 for (; offset < PAGE_SIZE && kaddr[offset];
1694                                 offset++, bprm->p++)
1695                         ;
1696
1697                 kunmap_local(kaddr);
1698                 put_arg_page(page);
1699         } while (offset == PAGE_SIZE);
1700
1701         bprm->p++;
1702         bprm->argc--;
1703         ret = 0;
1704
1705 out:
1706         return ret;
1707 }
1708 EXPORT_SYMBOL(remove_arg_zero);
1709
1710 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1711 /*
1712  * cycle the list of binary formats handler, until one recognizes the image
1713  */
1714 static int search_binary_handler(struct linux_binprm *bprm)
1715 {
1716         bool need_retry = IS_ENABLED(CONFIG_MODULES);
1717         struct linux_binfmt *fmt;
1718         int retval;
1719
1720         retval = prepare_binprm(bprm);
1721         if (retval < 0)
1722                 return retval;
1723
1724         retval = security_bprm_check(bprm);
1725         if (retval)
1726                 return retval;
1727
1728         retval = -ENOENT;
1729  retry:
1730         read_lock(&binfmt_lock);
1731         list_for_each_entry(fmt, &formats, lh) {
1732                 if (!try_module_get(fmt->module))
1733                         continue;
1734                 read_unlock(&binfmt_lock);
1735
1736                 retval = fmt->load_binary(bprm);
1737
1738                 read_lock(&binfmt_lock);
1739                 put_binfmt(fmt);
1740                 if (bprm->point_of_no_return || (retval != -ENOEXEC)) {
1741                         read_unlock(&binfmt_lock);
1742                         return retval;
1743                 }
1744         }
1745         read_unlock(&binfmt_lock);
1746
1747         if (need_retry) {
1748                 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1749                     printable(bprm->buf[2]) && printable(bprm->buf[3]))
1750                         return retval;
1751                 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1752                         return retval;
1753                 need_retry = false;
1754                 goto retry;
1755         }
1756
1757         return retval;
1758 }
1759
1760 static int exec_binprm(struct linux_binprm *bprm)
1761 {
1762         pid_t old_pid, old_vpid;
1763         int ret, depth;
1764
1765         /* Need to fetch pid before load_binary changes it */
1766         old_pid = current->pid;
1767         rcu_read_lock();
1768         old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1769         rcu_read_unlock();
1770
1771         /* This allows 4 levels of binfmt rewrites before failing hard. */
1772         for (depth = 0;; depth++) {
1773                 struct file *exec;
1774                 if (depth > 5)
1775                         return -ELOOP;
1776
1777                 ret = search_binary_handler(bprm);
1778                 if (ret < 0)
1779                         return ret;
1780                 if (!bprm->interpreter)
1781                         break;
1782
1783                 exec = bprm->file;
1784                 bprm->file = bprm->interpreter;
1785                 bprm->interpreter = NULL;
1786
1787                 allow_write_access(exec);
1788                 if (unlikely(bprm->have_execfd)) {
1789                         if (bprm->executable) {
1790                                 fput(exec);
1791                                 return -ENOEXEC;
1792                         }
1793                         bprm->executable = exec;
1794                 } else
1795                         fput(exec);
1796         }
1797
1798         audit_bprm(bprm);
1799         trace_sched_process_exec(current, old_pid, bprm);
1800         ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1801         proc_exec_connector(current);
1802         return 0;
1803 }
1804
1805 /*
1806  * sys_execve() executes a new program.
1807  */
1808 static int bprm_execve(struct linux_binprm *bprm,
1809                        int fd, struct filename *filename, int flags)
1810 {
1811         struct file *file;
1812         int retval;
1813
1814         retval = prepare_bprm_creds(bprm);
1815         if (retval)
1816                 return retval;
1817
1818         check_unsafe_exec(bprm);
1819         current->in_execve = 1;
1820
1821         file = do_open_execat(fd, filename, flags);
1822         retval = PTR_ERR(file);
1823         if (IS_ERR(file))
1824                 goto out_unmark;
1825
1826         sched_exec();
1827
1828         bprm->file = file;
1829         /*
1830          * Record that a name derived from an O_CLOEXEC fd will be
1831          * inaccessible after exec.  This allows the code in exec to
1832          * choose to fail when the executable is not mmaped into the
1833          * interpreter and an open file descriptor is not passed to
1834          * the interpreter.  This makes for a better user experience
1835          * than having the interpreter start and then immediately fail
1836          * when it finds the executable is inaccessible.
1837          */
1838         if (bprm->fdpath && get_close_on_exec(fd))
1839                 bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1840
1841         /* Set the unchanging part of bprm->cred */
1842         retval = security_bprm_creds_for_exec(bprm);
1843         if (retval)
1844                 goto out;
1845
1846         retval = exec_binprm(bprm);
1847         if (retval < 0)
1848                 goto out;
1849
1850         /* execve succeeded */
1851         current->fs->in_exec = 0;
1852         current->in_execve = 0;
1853         rseq_execve(current);
1854         acct_update_integrals(current);
1855         task_numa_free(current, false);
1856         return retval;
1857
1858 out:
1859         /*
1860          * If past the point of no return ensure the code never
1861          * returns to the userspace process.  Use an existing fatal
1862          * signal if present otherwise terminate the process with
1863          * SIGSEGV.
1864          */
1865         if (bprm->point_of_no_return && !fatal_signal_pending(current))
1866                 force_fatal_sig(SIGSEGV);
1867
1868 out_unmark:
1869         current->fs->in_exec = 0;
1870         current->in_execve = 0;
1871
1872         return retval;
1873 }
1874
1875 static int do_execveat_common(int fd, struct filename *filename,
1876                               struct user_arg_ptr argv,
1877                               struct user_arg_ptr envp,
1878                               int flags)
1879 {
1880         struct linux_binprm *bprm;
1881         int retval;
1882
1883         if (IS_ERR(filename))
1884                 return PTR_ERR(filename);
1885
1886         /*
1887          * We move the actual failure in case of RLIMIT_NPROC excess from
1888          * set*uid() to execve() because too many poorly written programs
1889          * don't check setuid() return code.  Here we additionally recheck
1890          * whether NPROC limit is still exceeded.
1891          */
1892         if ((current->flags & PF_NPROC_EXCEEDED) &&
1893             is_ucounts_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
1894                 retval = -EAGAIN;
1895                 goto out_ret;
1896         }
1897
1898         /* We're below the limit (still or again), so we don't want to make
1899          * further execve() calls fail. */
1900         current->flags &= ~PF_NPROC_EXCEEDED;
1901
1902         bprm = alloc_bprm(fd, filename);
1903         if (IS_ERR(bprm)) {
1904                 retval = PTR_ERR(bprm);
1905                 goto out_ret;
1906         }
1907
1908         retval = count(argv, MAX_ARG_STRINGS);
1909         if (retval == 0)
1910                 pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n",
1911                              current->comm, bprm->filename);
1912         if (retval < 0)
1913                 goto out_free;
1914         bprm->argc = retval;
1915
1916         retval = count(envp, MAX_ARG_STRINGS);
1917         if (retval < 0)
1918                 goto out_free;
1919         bprm->envc = retval;
1920
1921         retval = bprm_stack_limits(bprm);
1922         if (retval < 0)
1923                 goto out_free;
1924
1925         retval = copy_string_kernel(bprm->filename, bprm);
1926         if (retval < 0)
1927                 goto out_free;
1928         bprm->exec = bprm->p;
1929
1930         retval = copy_strings(bprm->envc, envp, bprm);
1931         if (retval < 0)
1932                 goto out_free;
1933
1934         retval = copy_strings(bprm->argc, argv, bprm);
1935         if (retval < 0)
1936                 goto out_free;
1937
1938         /*
1939          * When argv is empty, add an empty string ("") as argv[0] to
1940          * ensure confused userspace programs that start processing
1941          * from argv[1] won't end up walking envp. See also
1942          * bprm_stack_limits().
1943          */
1944         if (bprm->argc == 0) {
1945                 retval = copy_string_kernel("", bprm);
1946                 if (retval < 0)
1947                         goto out_free;
1948                 bprm->argc = 1;
1949         }
1950
1951         retval = bprm_execve(bprm, fd, filename, flags);
1952 out_free:
1953         free_bprm(bprm);
1954
1955 out_ret:
1956         putname(filename);
1957         return retval;
1958 }
1959
1960 int kernel_execve(const char *kernel_filename,
1961                   const char *const *argv, const char *const *envp)
1962 {
1963         struct filename *filename;
1964         struct linux_binprm *bprm;
1965         int fd = AT_FDCWD;
1966         int retval;
1967
1968         /* It is non-sense for kernel threads to call execve */
1969         if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
1970                 return -EINVAL;
1971
1972         filename = getname_kernel(kernel_filename);
1973         if (IS_ERR(filename))
1974                 return PTR_ERR(filename);
1975
1976         bprm = alloc_bprm(fd, filename);
1977         if (IS_ERR(bprm)) {
1978                 retval = PTR_ERR(bprm);
1979                 goto out_ret;
1980         }
1981
1982         retval = count_strings_kernel(argv);
1983         if (WARN_ON_ONCE(retval == 0))
1984                 retval = -EINVAL;
1985         if (retval < 0)
1986                 goto out_free;
1987         bprm->argc = retval;
1988
1989         retval = count_strings_kernel(envp);
1990         if (retval < 0)
1991                 goto out_free;
1992         bprm->envc = retval;
1993
1994         retval = bprm_stack_limits(bprm);
1995         if (retval < 0)
1996                 goto out_free;
1997
1998         retval = copy_string_kernel(bprm->filename, bprm);
1999         if (retval < 0)
2000                 goto out_free;
2001         bprm->exec = bprm->p;
2002
2003         retval = copy_strings_kernel(bprm->envc, envp, bprm);
2004         if (retval < 0)
2005                 goto out_free;
2006
2007         retval = copy_strings_kernel(bprm->argc, argv, bprm);
2008         if (retval < 0)
2009                 goto out_free;
2010
2011         retval = bprm_execve(bprm, fd, filename, 0);
2012 out_free:
2013         free_bprm(bprm);
2014 out_ret:
2015         putname(filename);
2016         return retval;
2017 }
2018
2019 static int do_execve(struct filename *filename,
2020         const char __user *const __user *__argv,
2021         const char __user *const __user *__envp)
2022 {
2023         struct user_arg_ptr argv = { .ptr.native = __argv };
2024         struct user_arg_ptr envp = { .ptr.native = __envp };
2025         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2026 }
2027
2028 static int do_execveat(int fd, struct filename *filename,
2029                 const char __user *const __user *__argv,
2030                 const char __user *const __user *__envp,
2031                 int flags)
2032 {
2033         struct user_arg_ptr argv = { .ptr.native = __argv };
2034         struct user_arg_ptr envp = { .ptr.native = __envp };
2035
2036         return do_execveat_common(fd, filename, argv, envp, flags);
2037 }
2038
2039 #ifdef CONFIG_COMPAT
2040 static int compat_do_execve(struct filename *filename,
2041         const compat_uptr_t __user *__argv,
2042         const compat_uptr_t __user *__envp)
2043 {
2044         struct user_arg_ptr argv = {
2045                 .is_compat = true,
2046                 .ptr.compat = __argv,
2047         };
2048         struct user_arg_ptr envp = {
2049                 .is_compat = true,
2050                 .ptr.compat = __envp,
2051         };
2052         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2053 }
2054
2055 static int compat_do_execveat(int fd, struct filename *filename,
2056                               const compat_uptr_t __user *__argv,
2057                               const compat_uptr_t __user *__envp,
2058                               int flags)
2059 {
2060         struct user_arg_ptr argv = {
2061                 .is_compat = true,
2062                 .ptr.compat = __argv,
2063         };
2064         struct user_arg_ptr envp = {
2065                 .is_compat = true,
2066                 .ptr.compat = __envp,
2067         };
2068         return do_execveat_common(fd, filename, argv, envp, flags);
2069 }
2070 #endif
2071
2072 void set_binfmt(struct linux_binfmt *new)
2073 {
2074         struct mm_struct *mm = current->mm;
2075
2076         if (mm->binfmt)
2077                 module_put(mm->binfmt->module);
2078
2079         mm->binfmt = new;
2080         if (new)
2081                 __module_get(new->module);
2082 }
2083 EXPORT_SYMBOL(set_binfmt);
2084
2085 /*
2086  * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
2087  */
2088 void set_dumpable(struct mm_struct *mm, int value)
2089 {
2090         if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
2091                 return;
2092
2093         set_mask_bits(&mm->flags, MMF_DUMPABLE_MASK, value);
2094 }
2095
2096 SYSCALL_DEFINE3(execve,
2097                 const char __user *, filename,
2098                 const char __user *const __user *, argv,
2099                 const char __user *const __user *, envp)
2100 {
2101         return do_execve(getname(filename), argv, envp);
2102 }
2103
2104 SYSCALL_DEFINE5(execveat,
2105                 int, fd, const char __user *, filename,
2106                 const char __user *const __user *, argv,
2107                 const char __user *const __user *, envp,
2108                 int, flags)
2109 {
2110         return do_execveat(fd,
2111                            getname_uflags(filename, flags),
2112                            argv, envp, flags);
2113 }
2114
2115 #ifdef CONFIG_COMPAT
2116 COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
2117         const compat_uptr_t __user *, argv,
2118         const compat_uptr_t __user *, envp)
2119 {
2120         return compat_do_execve(getname(filename), argv, envp);
2121 }
2122
2123 COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
2124                        const char __user *, filename,
2125                        const compat_uptr_t __user *, argv,
2126                        const compat_uptr_t __user *, envp,
2127                        int,  flags)
2128 {
2129         return compat_do_execveat(fd,
2130                                   getname_uflags(filename, flags),
2131                                   argv, envp, flags);
2132 }
2133 #endif
2134
2135 #ifdef CONFIG_SYSCTL
2136
2137 static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
2138                 void *buffer, size_t *lenp, loff_t *ppos)
2139 {
2140         int error = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
2141
2142         if (!error)
2143                 validate_coredump_safety();
2144         return error;
2145 }
2146
2147 static struct ctl_table fs_exec_sysctls[] = {
2148         {
2149                 .procname       = "suid_dumpable",
2150                 .data           = &suid_dumpable,
2151                 .maxlen         = sizeof(int),
2152                 .mode           = 0644,
2153                 .proc_handler   = proc_dointvec_minmax_coredump,
2154                 .extra1         = SYSCTL_ZERO,
2155                 .extra2         = SYSCTL_TWO,
2156         },
2157         { }
2158 };
2159
2160 static int __init init_fs_exec_sysctls(void)
2161 {
2162         register_sysctl_init("fs", fs_exec_sysctls);
2163         return 0;
2164 }
2165
2166 fs_initcall(init_fs_exec_sysctls);
2167 #endif /* CONFIG_SYSCTL */