| 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * linux/kernel/seccomp.c |
| 4 | * |
| 5 | * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com> |
| 6 | * |
| 7 | * Copyright (C) 2012 Google, Inc. |
| 8 | * Will Drewry <wad@chromium.org> |
| 9 | * |
| 10 | * This defines a simple but solid secure-computing facility. |
| 11 | * |
| 12 | * Mode 1 uses a fixed list of allowed system calls. |
| 13 | * Mode 2 allows user-defined system call filters in the form |
| 14 | * of Berkeley Packet Filters/Linux Socket Filters. |
| 15 | */ |
| 16 | |
| 17 | #include <linux/refcount.h> |
| 18 | #include <linux/audit.h> |
| 19 | #include <linux/compat.h> |
| 20 | #include <linux/coredump.h> |
| 21 | #include <linux/kmemleak.h> |
| 22 | #include <linux/nospec.h> |
| 23 | #include <linux/prctl.h> |
| 24 | #include <linux/sched.h> |
| 25 | #include <linux/sched/task_stack.h> |
| 26 | #include <linux/seccomp.h> |
| 27 | #include <linux/slab.h> |
| 28 | #include <linux/syscalls.h> |
| 29 | #include <linux/sysctl.h> |
| 30 | |
| 31 | #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER |
| 32 | #include <asm/syscall.h> |
| 33 | #endif |
| 34 | |
| 35 | #ifdef CONFIG_SECCOMP_FILTER |
| 36 | #include <linux/filter.h> |
| 37 | #include <linux/pid.h> |
| 38 | #include <linux/ptrace.h> |
| 39 | #include <linux/security.h> |
| 40 | #include <linux/tracehook.h> |
| 41 | #include <linux/uaccess.h> |
| 42 | |
| 43 | /** |
| 44 | * struct seccomp_filter - container for seccomp BPF programs |
| 45 | * |
| 46 | * @usage: reference count to manage the object lifetime. |
| 47 | * get/put helpers should be used when accessing an instance |
| 48 | * outside of a lifetime-guarded section. In general, this |
| 49 | * is only needed for handling filters shared across tasks. |
| 50 | * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged |
| 51 | * @prev: points to a previously installed, or inherited, filter |
| 52 | * @prog: the BPF program to evaluate |
| 53 | * |
| 54 | * seccomp_filter objects are organized in a tree linked via the @prev |
| 55 | * pointer. For any task, it appears to be a singly-linked list starting |
| 56 | * with current->seccomp.filter, the most recently attached or inherited filter. |
| 57 | * However, multiple filters may share a @prev node, by way of fork(), which |
| 58 | * results in a unidirectional tree existing in memory. This is similar to |
| 59 | * how namespaces work. |
| 60 | * |
| 61 | * seccomp_filter objects should never be modified after being attached |
| 62 | * to a task_struct (other than @usage). |
| 63 | */ |
| 64 | struct seccomp_filter { |
| 65 | refcount_t usage; |
| 66 | bool log; |
| 67 | struct seccomp_filter *prev; |
| 68 | struct bpf_prog *prog; |
| 69 | }; |
| 70 | |
| 71 | /* Limit any path through the tree to 256KB worth of instructions. */ |
| 72 | #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter)) |
| 73 | |
| 74 | /* |
| 75 | * Endianness is explicitly ignored and left for BPF program authors to manage |
| 76 | * as per the specific architecture. |
| 77 | */ |
| 78 | static void populate_seccomp_data(struct seccomp_data *sd) |
| 79 | { |
| 80 | struct task_struct *task = current; |
| 81 | struct pt_regs *regs = task_pt_regs(task); |
| 82 | unsigned long args[6]; |
| 83 | |
| 84 | sd->nr = syscall_get_nr(task, regs); |
| 85 | sd->arch = syscall_get_arch(); |
| 86 | syscall_get_arguments(task, regs, 0, 6, args); |
| 87 | sd->args[0] = args[0]; |
| 88 | sd->args[1] = args[1]; |
| 89 | sd->args[2] = args[2]; |
| 90 | sd->args[3] = args[3]; |
| 91 | sd->args[4] = args[4]; |
| 92 | sd->args[5] = args[5]; |
| 93 | sd->instruction_pointer = KSTK_EIP(task); |
| 94 | } |
| 95 | |
| 96 | /** |
| 97 | * seccomp_check_filter - verify seccomp filter code |
| 98 | * @filter: filter to verify |
| 99 | * @flen: length of filter |
| 100 | * |
| 101 | * Takes a previously checked filter (by bpf_check_classic) and |
| 102 | * redirects all filter code that loads struct sk_buff data |
| 103 | * and related data through seccomp_bpf_load. It also |
| 104 | * enforces length and alignment checking of those loads. |
| 105 | * |
| 106 | * Returns 0 if the rule set is legal or -EINVAL if not. |
| 107 | */ |
| 108 | static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen) |
| 109 | { |
| 110 | int pc; |
| 111 | for (pc = 0; pc < flen; pc++) { |
| 112 | struct sock_filter *ftest = &filter[pc]; |
| 113 | u16 code = ftest->code; |
| 114 | u32 k = ftest->k; |
| 115 | |
| 116 | switch (code) { |
| 117 | case BPF_LD | BPF_W | BPF_ABS: |
| 118 | ftest->code = BPF_LDX | BPF_W | BPF_ABS; |
| 119 | /* 32-bit aligned and not out of bounds. */ |
| 120 | if (k >= sizeof(struct seccomp_data) || k & 3) |
| 121 | return -EINVAL; |
| 122 | continue; |
| 123 | case BPF_LD | BPF_W | BPF_LEN: |
| 124 | ftest->code = BPF_LD | BPF_IMM; |
| 125 | ftest->k = sizeof(struct seccomp_data); |
| 126 | continue; |
| 127 | case BPF_LDX | BPF_W | BPF_LEN: |
| 128 | ftest->code = BPF_LDX | BPF_IMM; |
| 129 | ftest->k = sizeof(struct seccomp_data); |
| 130 | continue; |
| 131 | /* Explicitly include allowed calls. */ |
| 132 | case BPF_RET | BPF_K: |
| 133 | case BPF_RET | BPF_A: |
| 134 | case BPF_ALU | BPF_ADD | BPF_K: |
| 135 | case BPF_ALU | BPF_ADD | BPF_X: |
| 136 | case BPF_ALU | BPF_SUB | BPF_K: |
| 137 | case BPF_ALU | BPF_SUB | BPF_X: |
| 138 | case BPF_ALU | BPF_MUL | BPF_K: |
| 139 | case BPF_ALU | BPF_MUL | BPF_X: |
| 140 | case BPF_ALU | BPF_DIV | BPF_K: |
| 141 | case BPF_ALU | BPF_DIV | BPF_X: |
| 142 | case BPF_ALU | BPF_AND | BPF_K: |
| 143 | case BPF_ALU | BPF_AND | BPF_X: |
| 144 | case BPF_ALU | BPF_OR | BPF_K: |
| 145 | case BPF_ALU | BPF_OR | BPF_X: |
| 146 | case BPF_ALU | BPF_XOR | BPF_K: |
| 147 | case BPF_ALU | BPF_XOR | BPF_X: |
| 148 | case BPF_ALU | BPF_LSH | BPF_K: |
| 149 | case BPF_ALU | BPF_LSH | BPF_X: |
| 150 | case BPF_ALU | BPF_RSH | BPF_K: |
| 151 | case BPF_ALU | BPF_RSH | BPF_X: |
| 152 | case BPF_ALU | BPF_NEG: |
| 153 | case BPF_LD | BPF_IMM: |
| 154 | case BPF_LDX | BPF_IMM: |
| 155 | case BPF_MISC | BPF_TAX: |
| 156 | case BPF_MISC | BPF_TXA: |
| 157 | case BPF_LD | BPF_MEM: |
| 158 | case BPF_LDX | BPF_MEM: |
| 159 | case BPF_ST: |
| 160 | case BPF_STX: |
| 161 | case BPF_JMP | BPF_JA: |
| 162 | case BPF_JMP | BPF_JEQ | BPF_K: |
| 163 | case BPF_JMP | BPF_JEQ | BPF_X: |
| 164 | case BPF_JMP | BPF_JGE | BPF_K: |
| 165 | case BPF_JMP | BPF_JGE | BPF_X: |
| 166 | case BPF_JMP | BPF_JGT | BPF_K: |
| 167 | case BPF_JMP | BPF_JGT | BPF_X: |
| 168 | case BPF_JMP | BPF_JSET | BPF_K: |
| 169 | case BPF_JMP | BPF_JSET | BPF_X: |
| 170 | continue; |
| 171 | default: |
| 172 | return -EINVAL; |
| 173 | } |
| 174 | } |
| 175 | return 0; |
| 176 | } |
| 177 | |
| 178 | /** |
| 179 | * seccomp_run_filters - evaluates all seccomp filters against @sd |
| 180 | * @sd: optional seccomp data to be passed to filters |
| 181 | * @match: stores struct seccomp_filter that resulted in the return value, |
| 182 | * unless filter returned SECCOMP_RET_ALLOW, in which case it will |
| 183 | * be unchanged. |
| 184 | * |
| 185 | * Returns valid seccomp BPF response codes. |
| 186 | */ |
| 187 | #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL))) |
| 188 | static u32 seccomp_run_filters(const struct seccomp_data *sd, |
| 189 | struct seccomp_filter **match) |
| 190 | { |
| 191 | struct seccomp_data sd_local; |
| 192 | u32 ret = SECCOMP_RET_ALLOW; |
| 193 | /* Make sure cross-thread synced filter points somewhere sane. */ |
| 194 | struct seccomp_filter *f = |
| 195 | READ_ONCE(current->seccomp.filter); |
| 196 | |
| 197 | /* Ensure unexpected behavior doesn't result in failing open. */ |
| 198 | if (WARN_ON(f == NULL)) |
| 199 | return SECCOMP_RET_KILL_PROCESS; |
| 200 | |
| 201 | if (!sd) { |
| 202 | populate_seccomp_data(&sd_local); |
| 203 | sd = &sd_local; |
| 204 | } |
| 205 | |
| 206 | /* |
| 207 | * All filters in the list are evaluated and the lowest BPF return |
| 208 | * value always takes priority (ignoring the DATA). |
| 209 | */ |
| 210 | for (; f; f = f->prev) { |
| 211 | u32 cur_ret = BPF_PROG_RUN(f->prog, sd); |
| 212 | |
| 213 | if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) { |
| 214 | ret = cur_ret; |
| 215 | *match = f; |
| 216 | } |
| 217 | } |
| 218 | return ret; |
| 219 | } |
| 220 | #endif /* CONFIG_SECCOMP_FILTER */ |
| 221 | |
| 222 | static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode) |
| 223 | { |
| 224 | assert_spin_locked(¤t->sighand->siglock); |
| 225 | |
| 226 | if (current->seccomp.mode && current->seccomp.mode != seccomp_mode) |
| 227 | return false; |
| 228 | |
| 229 | return true; |
| 230 | } |
| 231 | |
| 232 | void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { } |
| 233 | |
| 234 | static inline void seccomp_assign_mode(struct task_struct *task, |
| 235 | unsigned long seccomp_mode, |
| 236 | unsigned long flags) |
| 237 | { |
| 238 | assert_spin_locked(&task->sighand->siglock); |
| 239 | |
| 240 | task->seccomp.mode = seccomp_mode; |
| 241 | /* |
| 242 | * Make sure TIF_SECCOMP cannot be set before the mode (and |
| 243 | * filter) is set. |
| 244 | */ |
| 245 | smp_mb__before_atomic(); |
| 246 | /* Assume default seccomp processes want spec flaw mitigation. */ |
| 247 | if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0) |
| 248 | arch_seccomp_spec_mitigate(task); |
| 249 | set_tsk_thread_flag(task, TIF_SECCOMP); |
| 250 | } |
| 251 | |
| 252 | #ifdef CONFIG_SECCOMP_FILTER |
| 253 | /* Returns 1 if the parent is an ancestor of the child. */ |
| 254 | static int is_ancestor(struct seccomp_filter *parent, |
| 255 | struct seccomp_filter *child) |
| 256 | { |
| 257 | /* NULL is the root ancestor. */ |
| 258 | if (parent == NULL) |
| 259 | return 1; |
| 260 | for (; child; child = child->prev) |
| 261 | if (child == parent) |
| 262 | return 1; |
| 263 | return 0; |
| 264 | } |
| 265 | |
| 266 | /** |
| 267 | * seccomp_can_sync_threads: checks if all threads can be synchronized |
| 268 | * |
| 269 | * Expects sighand and cred_guard_mutex locks to be held. |
| 270 | * |
| 271 | * Returns 0 on success, -ve on error, or the pid of a thread which was |
| 272 | * either not in the correct seccomp mode or it did not have an ancestral |
| 273 | * seccomp filter. |
| 274 | */ |
| 275 | static inline pid_t seccomp_can_sync_threads(void) |
| 276 | { |
| 277 | struct task_struct *thread, *caller; |
| 278 | |
| 279 | BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex)); |
| 280 | assert_spin_locked(¤t->sighand->siglock); |
| 281 | |
| 282 | /* Validate all threads being eligible for synchronization. */ |
| 283 | caller = current; |
| 284 | for_each_thread(caller, thread) { |
| 285 | pid_t failed; |
| 286 | |
| 287 | /* Skip current, since it is initiating the sync. */ |
| 288 | if (thread == caller) |
| 289 | continue; |
| 290 | |
| 291 | if (thread->seccomp.mode == SECCOMP_MODE_DISABLED || |
| 292 | (thread->seccomp.mode == SECCOMP_MODE_FILTER && |
| 293 | is_ancestor(thread->seccomp.filter, |
| 294 | caller->seccomp.filter))) |
| 295 | continue; |
| 296 | |
| 297 | /* Return the first thread that cannot be synchronized. */ |
| 298 | failed = task_pid_vnr(thread); |
| 299 | /* If the pid cannot be resolved, then return -ESRCH */ |
| 300 | if (WARN_ON(failed == 0)) |
| 301 | failed = -ESRCH; |
| 302 | return failed; |
| 303 | } |
| 304 | |
| 305 | return 0; |
| 306 | } |
| 307 | |
| 308 | /** |
| 309 | * seccomp_sync_threads: sets all threads to use current's filter |
| 310 | * |
| 311 | * Expects sighand and cred_guard_mutex locks to be held, and for |
| 312 | * seccomp_can_sync_threads() to have returned success already |
| 313 | * without dropping the locks. |
| 314 | * |
| 315 | */ |
| 316 | static inline void seccomp_sync_threads(unsigned long flags) |
| 317 | { |
| 318 | struct task_struct *thread, *caller; |
| 319 | |
| 320 | BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex)); |
| 321 | assert_spin_locked(¤t->sighand->siglock); |
| 322 | |
| 323 | /* Synchronize all threads. */ |
| 324 | caller = current; |
| 325 | for_each_thread(caller, thread) { |
| 326 | /* Skip current, since it needs no changes. */ |
| 327 | if (thread == caller) |
| 328 | continue; |
| 329 | |
| 330 | /* Get a task reference for the new leaf node. */ |
| 331 | get_seccomp_filter(caller); |
| 332 | /* |
| 333 | * Drop the task reference to the shared ancestor since |
| 334 | * current's path will hold a reference. (This also |
| 335 | * allows a put before the assignment.) |
| 336 | */ |
| 337 | put_seccomp_filter(thread); |
| 338 | smp_store_release(&thread->seccomp.filter, |
| 339 | caller->seccomp.filter); |
| 340 | |
| 341 | /* |
| 342 | * Don't let an unprivileged task work around |
| 343 | * the no_new_privs restriction by creating |
| 344 | * a thread that sets it up, enters seccomp, |
| 345 | * then dies. |
| 346 | */ |
| 347 | if (task_no_new_privs(caller)) |
| 348 | task_set_no_new_privs(thread); |
| 349 | |
| 350 | /* |
| 351 | * Opt the other thread into seccomp if needed. |
| 352 | * As threads are considered to be trust-realm |
| 353 | * equivalent (see ptrace_may_access), it is safe to |
| 354 | * allow one thread to transition the other. |
| 355 | */ |
| 356 | if (thread->seccomp.mode == SECCOMP_MODE_DISABLED) |
| 357 | seccomp_assign_mode(thread, SECCOMP_MODE_FILTER, |
| 358 | flags); |
| 359 | } |
| 360 | } |
| 361 | |
| 362 | /** |
| 363 | * seccomp_prepare_filter: Prepares a seccomp filter for use. |
| 364 | * @fprog: BPF program to install |
| 365 | * |
| 366 | * Returns filter on success or an ERR_PTR on failure. |
| 367 | */ |
| 368 | static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog) |
| 369 | { |
| 370 | struct seccomp_filter *sfilter; |
| 371 | int ret; |
| 372 | const bool save_orig = IS_ENABLED(CONFIG_CHECKPOINT_RESTORE); |
| 373 | |
| 374 | if (fprog->len == 0 || fprog->len > BPF_MAXINSNS) |
| 375 | return ERR_PTR(-EINVAL); |
| 376 | |
| 377 | BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter)); |
| 378 | |
| 379 | /* |
| 380 | * Installing a seccomp filter requires that the task has |
| 381 | * CAP_SYS_ADMIN in its namespace or be running with no_new_privs. |
| 382 | * This avoids scenarios where unprivileged tasks can affect the |
| 383 | * behavior of privileged children. |
| 384 | */ |
| 385 | if (!task_no_new_privs(current) && |
| 386 | security_capable_noaudit(current_cred(), current_user_ns(), |
| 387 | CAP_SYS_ADMIN) != 0) |
| 388 | return ERR_PTR(-EACCES); |
| 389 | |
| 390 | /* Allocate a new seccomp_filter */ |
| 391 | sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN); |
| 392 | if (!sfilter) |
| 393 | return ERR_PTR(-ENOMEM); |
| 394 | |
| 395 | ret = bpf_prog_create_from_user(&sfilter->prog, fprog, |
| 396 | seccomp_check_filter, save_orig); |
| 397 | if (ret < 0) { |
| 398 | kfree(sfilter); |
| 399 | return ERR_PTR(ret); |
| 400 | } |
| 401 | |
| 402 | refcount_set(&sfilter->usage, 1); |
| 403 | |
| 404 | return sfilter; |
| 405 | } |
| 406 | |
| 407 | /** |
| 408 | * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog |
| 409 | * @user_filter: pointer to the user data containing a sock_fprog. |
| 410 | * |
| 411 | * Returns 0 on success and non-zero otherwise. |
| 412 | */ |
| 413 | static struct seccomp_filter * |
| 414 | seccomp_prepare_user_filter(const char __user *user_filter) |
| 415 | { |
| 416 | struct sock_fprog fprog; |
| 417 | struct seccomp_filter *filter = ERR_PTR(-EFAULT); |
| 418 | |
| 419 | #ifdef CONFIG_COMPAT |
| 420 | if (in_compat_syscall()) { |
| 421 | struct compat_sock_fprog fprog32; |
| 422 | if (copy_from_user(&fprog32, user_filter, sizeof(fprog32))) |
| 423 | goto out; |
| 424 | fprog.len = fprog32.len; |
| 425 | fprog.filter = compat_ptr(fprog32.filter); |
| 426 | } else /* falls through to the if below. */ |
| 427 | #endif |
| 428 | if (copy_from_user(&fprog, user_filter, sizeof(fprog))) |
| 429 | goto out; |
| 430 | filter = seccomp_prepare_filter(&fprog); |
| 431 | out: |
| 432 | return filter; |
| 433 | } |
| 434 | |
| 435 | /** |
| 436 | * seccomp_attach_filter: validate and attach filter |
| 437 | * @flags: flags to change filter behavior |
| 438 | * @filter: seccomp filter to add to the current process |
| 439 | * |
| 440 | * Caller must be holding current->sighand->siglock lock. |
| 441 | * |
| 442 | * Returns 0 on success, -ve on error. |
| 443 | */ |
| 444 | static long seccomp_attach_filter(unsigned int flags, |
| 445 | struct seccomp_filter *filter) |
| 446 | { |
| 447 | unsigned long total_insns; |
| 448 | struct seccomp_filter *walker; |
| 449 | |
| 450 | assert_spin_locked(¤t->sighand->siglock); |
| 451 | |
| 452 | /* Validate resulting filter length. */ |
| 453 | total_insns = filter->prog->len; |
| 454 | for (walker = current->seccomp.filter; walker; walker = walker->prev) |
| 455 | total_insns += walker->prog->len + 4; /* 4 instr penalty */ |
| 456 | if (total_insns > MAX_INSNS_PER_PATH) |
| 457 | return -ENOMEM; |
| 458 | |
| 459 | /* If thread sync has been requested, check that it is possible. */ |
| 460 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) { |
| 461 | int ret; |
| 462 | |
| 463 | ret = seccomp_can_sync_threads(); |
| 464 | if (ret) |
| 465 | return ret; |
| 466 | } |
| 467 | |
| 468 | /* Set log flag, if present. */ |
| 469 | if (flags & SECCOMP_FILTER_FLAG_LOG) |
| 470 | filter->log = true; |
| 471 | |
| 472 | /* |
| 473 | * If there is an existing filter, make it the prev and don't drop its |
| 474 | * task reference. |
| 475 | */ |
| 476 | filter->prev = current->seccomp.filter; |
| 477 | current->seccomp.filter = filter; |
| 478 | |
| 479 | /* Now that the new filter is in place, synchronize to all threads. */ |
| 480 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) |
| 481 | seccomp_sync_threads(flags); |
| 482 | |
| 483 | return 0; |
| 484 | } |
| 485 | |
| 486 | static void __get_seccomp_filter(struct seccomp_filter *filter) |
| 487 | { |
| 488 | /* Reference count is bounded by the number of total processes. */ |
| 489 | refcount_inc(&filter->usage); |
| 490 | } |
| 491 | |
| 492 | /* get_seccomp_filter - increments the reference count of the filter on @tsk */ |
| 493 | void get_seccomp_filter(struct task_struct *tsk) |
| 494 | { |
| 495 | struct seccomp_filter *orig = tsk->seccomp.filter; |
| 496 | if (!orig) |
| 497 | return; |
| 498 | __get_seccomp_filter(orig); |
| 499 | } |
| 500 | |
| 501 | static inline void seccomp_filter_free(struct seccomp_filter *filter) |
| 502 | { |
| 503 | if (filter) { |
| 504 | bpf_prog_destroy(filter->prog); |
| 505 | kfree(filter); |
| 506 | } |
| 507 | } |
| 508 | |
| 509 | static void __put_seccomp_filter(struct seccomp_filter *orig) |
| 510 | { |
| 511 | /* Clean up single-reference branches iteratively. */ |
| 512 | while (orig && refcount_dec_and_test(&orig->usage)) { |
| 513 | struct seccomp_filter *freeme = orig; |
| 514 | orig = orig->prev; |
| 515 | seccomp_filter_free(freeme); |
| 516 | } |
| 517 | } |
| 518 | |
| 519 | /* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */ |
| 520 | void put_seccomp_filter(struct task_struct *tsk) |
| 521 | { |
| 522 | __put_seccomp_filter(tsk->seccomp.filter); |
| 523 | } |
| 524 | |
| 525 | static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason) |
| 526 | { |
| 527 | clear_siginfo(info); |
| 528 | info->si_signo = SIGSYS; |
| 529 | info->si_code = SYS_SECCOMP; |
| 530 | info->si_call_addr = (void __user *)KSTK_EIP(current); |
| 531 | info->si_errno = reason; |
| 532 | info->si_arch = syscall_get_arch(); |
| 533 | info->si_syscall = syscall; |
| 534 | } |
| 535 | |
| 536 | /** |
| 537 | * seccomp_send_sigsys - signals the task to allow in-process syscall emulation |
| 538 | * @syscall: syscall number to send to userland |
| 539 | * @reason: filter-supplied reason code to send to userland (via si_errno) |
| 540 | * |
| 541 | * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info. |
| 542 | */ |
| 543 | static void seccomp_send_sigsys(int syscall, int reason) |
| 544 | { |
| 545 | struct kernel_siginfo info; |
| 546 | seccomp_init_siginfo(&info, syscall, reason); |
| 547 | force_sig_info(SIGSYS, &info, current); |
| 548 | } |
| 549 | #endif /* CONFIG_SECCOMP_FILTER */ |
| 550 | |
| 551 | /* For use with seccomp_actions_logged */ |
| 552 | #define SECCOMP_LOG_KILL_PROCESS (1 << 0) |
| 553 | #define SECCOMP_LOG_KILL_THREAD (1 << 1) |
| 554 | #define SECCOMP_LOG_TRAP (1 << 2) |
| 555 | #define SECCOMP_LOG_ERRNO (1 << 3) |
| 556 | #define SECCOMP_LOG_TRACE (1 << 4) |
| 557 | #define SECCOMP_LOG_LOG (1 << 5) |
| 558 | #define SECCOMP_LOG_ALLOW (1 << 6) |
| 559 | |
| 560 | static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS | |
| 561 | SECCOMP_LOG_KILL_THREAD | |
| 562 | SECCOMP_LOG_TRAP | |
| 563 | SECCOMP_LOG_ERRNO | |
| 564 | SECCOMP_LOG_TRACE | |
| 565 | SECCOMP_LOG_LOG; |
| 566 | |
| 567 | static inline void seccomp_log(unsigned long syscall, long signr, u32 action, |
| 568 | bool requested) |
| 569 | { |
| 570 | bool log = false; |
| 571 | |
| 572 | switch (action) { |
| 573 | case SECCOMP_RET_ALLOW: |
| 574 | break; |
| 575 | case SECCOMP_RET_TRAP: |
| 576 | log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP; |
| 577 | break; |
| 578 | case SECCOMP_RET_ERRNO: |
| 579 | log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO; |
| 580 | break; |
| 581 | case SECCOMP_RET_TRACE: |
| 582 | log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE; |
| 583 | break; |
| 584 | case SECCOMP_RET_LOG: |
| 585 | log = seccomp_actions_logged & SECCOMP_LOG_LOG; |
| 586 | break; |
| 587 | case SECCOMP_RET_KILL_THREAD: |
| 588 | log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD; |
| 589 | break; |
| 590 | case SECCOMP_RET_KILL_PROCESS: |
| 591 | default: |
| 592 | log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS; |
| 593 | } |
| 594 | |
| 595 | /* |
| 596 | * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the |
| 597 | * FILTER_FLAG_LOG bit was set. The admin has the ability to silence |
| 598 | * any action from being logged by removing the action name from the |
| 599 | * seccomp_actions_logged sysctl. |
| 600 | */ |
| 601 | if (!log) |
| 602 | return; |
| 603 | |
| 604 | audit_seccomp(syscall, signr, action); |
| 605 | } |
| 606 | |
| 607 | /* |
| 608 | * Secure computing mode 1 allows only read/write/exit/sigreturn. |
| 609 | * To be fully secure this must be combined with rlimit |
| 610 | * to limit the stack allocations too. |
| 611 | */ |
| 612 | static const int mode1_syscalls[] = { |
| 613 | __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn, |
| 614 | 0, /* null terminated */ |
| 615 | }; |
| 616 | |
| 617 | static void __secure_computing_strict(int this_syscall) |
| 618 | { |
| 619 | const int *syscall_whitelist = mode1_syscalls; |
| 620 | #ifdef CONFIG_COMPAT |
| 621 | if (in_compat_syscall()) |
| 622 | syscall_whitelist = get_compat_mode1_syscalls(); |
| 623 | #endif |
| 624 | do { |
| 625 | if (*syscall_whitelist == this_syscall) |
| 626 | return; |
| 627 | } while (*++syscall_whitelist); |
| 628 | |
| 629 | #ifdef SECCOMP_DEBUG |
| 630 | dump_stack(); |
| 631 | #endif |
| 632 | seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true); |
| 633 | do_exit(SIGKILL); |
| 634 | } |
| 635 | |
| 636 | #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER |
| 637 | void secure_computing_strict(int this_syscall) |
| 638 | { |
| 639 | int mode = current->seccomp.mode; |
| 640 | |
| 641 | if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) && |
| 642 | unlikely(current->ptrace & PT_SUSPEND_SECCOMP)) |
| 643 | return; |
| 644 | |
| 645 | if (mode == SECCOMP_MODE_DISABLED) |
| 646 | return; |
| 647 | else if (mode == SECCOMP_MODE_STRICT) |
| 648 | __secure_computing_strict(this_syscall); |
| 649 | else |
| 650 | BUG(); |
| 651 | } |
| 652 | #else |
| 653 | |
| 654 | #ifdef CONFIG_SECCOMP_FILTER |
| 655 | static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, |
| 656 | const bool recheck_after_trace) |
| 657 | { |
| 658 | u32 filter_ret, action; |
| 659 | struct seccomp_filter *match = NULL; |
| 660 | int data; |
| 661 | |
| 662 | /* |
| 663 | * Make sure that any changes to mode from another thread have |
| 664 | * been seen after TIF_SECCOMP was seen. |
| 665 | */ |
| 666 | rmb(); |
| 667 | |
| 668 | filter_ret = seccomp_run_filters(sd, &match); |
| 669 | data = filter_ret & SECCOMP_RET_DATA; |
| 670 | action = filter_ret & SECCOMP_RET_ACTION_FULL; |
| 671 | |
| 672 | switch (action) { |
| 673 | case SECCOMP_RET_ERRNO: |
| 674 | /* Set low-order bits as an errno, capped at MAX_ERRNO. */ |
| 675 | if (data > MAX_ERRNO) |
| 676 | data = MAX_ERRNO; |
| 677 | syscall_set_return_value(current, task_pt_regs(current), |
| 678 | -data, 0); |
| 679 | goto skip; |
| 680 | |
| 681 | case SECCOMP_RET_TRAP: |
| 682 | /* Show the handler the original registers. */ |
| 683 | syscall_rollback(current, task_pt_regs(current)); |
| 684 | /* Let the filter pass back 16 bits of data. */ |
| 685 | seccomp_send_sigsys(this_syscall, data); |
| 686 | goto skip; |
| 687 | |
| 688 | case SECCOMP_RET_TRACE: |
| 689 | /* We've been put in this state by the ptracer already. */ |
| 690 | if (recheck_after_trace) |
| 691 | return 0; |
| 692 | |
| 693 | /* ENOSYS these calls if there is no tracer attached. */ |
| 694 | if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) { |
| 695 | syscall_set_return_value(current, |
| 696 | task_pt_regs(current), |
| 697 | -ENOSYS, 0); |
| 698 | goto skip; |
| 699 | } |
| 700 | |
| 701 | /* Allow the BPF to provide the event message */ |
| 702 | ptrace_event(PTRACE_EVENT_SECCOMP, data); |
| 703 | /* |
| 704 | * The delivery of a fatal signal during event |
| 705 | * notification may silently skip tracer notification, |
| 706 | * which could leave us with a potentially unmodified |
| 707 | * syscall that the tracer would have liked to have |
| 708 | * changed. Since the process is about to die, we just |
| 709 | * force the syscall to be skipped and let the signal |
| 710 | * kill the process and correctly handle any tracer exit |
| 711 | * notifications. |
| 712 | */ |
| 713 | if (fatal_signal_pending(current)) |
| 714 | goto skip; |
| 715 | /* Check if the tracer forced the syscall to be skipped. */ |
| 716 | this_syscall = syscall_get_nr(current, task_pt_regs(current)); |
| 717 | if (this_syscall < 0) |
| 718 | goto skip; |
| 719 | |
| 720 | /* |
| 721 | * Recheck the syscall, since it may have changed. This |
| 722 | * intentionally uses a NULL struct seccomp_data to force |
| 723 | * a reload of all registers. This does not goto skip since |
| 724 | * a skip would have already been reported. |
| 725 | */ |
| 726 | if (__seccomp_filter(this_syscall, NULL, true)) |
| 727 | return -1; |
| 728 | |
| 729 | return 0; |
| 730 | |
| 731 | case SECCOMP_RET_LOG: |
| 732 | seccomp_log(this_syscall, 0, action, true); |
| 733 | return 0; |
| 734 | |
| 735 | case SECCOMP_RET_ALLOW: |
| 736 | /* |
| 737 | * Note that the "match" filter will always be NULL for |
| 738 | * this action since SECCOMP_RET_ALLOW is the starting |
| 739 | * state in seccomp_run_filters(). |
| 740 | */ |
| 741 | return 0; |
| 742 | |
| 743 | case SECCOMP_RET_KILL_THREAD: |
| 744 | case SECCOMP_RET_KILL_PROCESS: |
| 745 | default: |
| 746 | seccomp_log(this_syscall, SIGSYS, action, true); |
| 747 | /* Dump core only if this is the last remaining thread. */ |
| 748 | if (action == SECCOMP_RET_KILL_PROCESS || |
| 749 | get_nr_threads(current) == 1) { |
| 750 | kernel_siginfo_t info; |
| 751 | |
| 752 | /* Show the original registers in the dump. */ |
| 753 | syscall_rollback(current, task_pt_regs(current)); |
| 754 | /* Trigger a manual coredump since do_exit skips it. */ |
| 755 | seccomp_init_siginfo(&info, this_syscall, data); |
| 756 | do_coredump(&info); |
| 757 | } |
| 758 | if (action == SECCOMP_RET_KILL_PROCESS) |
| 759 | do_group_exit(SIGSYS); |
| 760 | else |
| 761 | do_exit(SIGSYS); |
| 762 | } |
| 763 | |
| 764 | unreachable(); |
| 765 | |
| 766 | skip: |
| 767 | seccomp_log(this_syscall, 0, action, match ? match->log : false); |
| 768 | return -1; |
| 769 | } |
| 770 | #else |
| 771 | static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, |
| 772 | const bool recheck_after_trace) |
| 773 | { |
| 774 | BUG(); |
| 775 | } |
| 776 | #endif |
| 777 | |
| 778 | int __secure_computing(const struct seccomp_data *sd) |
| 779 | { |
| 780 | int mode = current->seccomp.mode; |
| 781 | int this_syscall; |
| 782 | |
| 783 | if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) && |
| 784 | unlikely(current->ptrace & PT_SUSPEND_SECCOMP)) |
| 785 | return 0; |
| 786 | |
| 787 | this_syscall = sd ? sd->nr : |
| 788 | syscall_get_nr(current, task_pt_regs(current)); |
| 789 | |
| 790 | switch (mode) { |
| 791 | case SECCOMP_MODE_STRICT: |
| 792 | __secure_computing_strict(this_syscall); /* may call do_exit */ |
| 793 | return 0; |
| 794 | case SECCOMP_MODE_FILTER: |
| 795 | return __seccomp_filter(this_syscall, sd, false); |
| 796 | default: |
| 797 | BUG(); |
| 798 | } |
| 799 | } |
| 800 | #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */ |
| 801 | |
| 802 | long prctl_get_seccomp(void) |
| 803 | { |
| 804 | return current->seccomp.mode; |
| 805 | } |
| 806 | |
| 807 | /** |
| 808 | * seccomp_set_mode_strict: internal function for setting strict seccomp |
| 809 | * |
| 810 | * Once current->seccomp.mode is non-zero, it may not be changed. |
| 811 | * |
| 812 | * Returns 0 on success or -EINVAL on failure. |
| 813 | */ |
| 814 | static long seccomp_set_mode_strict(void) |
| 815 | { |
| 816 | const unsigned long seccomp_mode = SECCOMP_MODE_STRICT; |
| 817 | long ret = -EINVAL; |
| 818 | |
| 819 | spin_lock_irq(¤t->sighand->siglock); |
| 820 | |
| 821 | if (!seccomp_may_assign_mode(seccomp_mode)) |
| 822 | goto out; |
| 823 | |
| 824 | #ifdef TIF_NOTSC |
| 825 | disable_TSC(); |
| 826 | #endif |
| 827 | seccomp_assign_mode(current, seccomp_mode, 0); |
| 828 | ret = 0; |
| 829 | |
| 830 | out: |
| 831 | spin_unlock_irq(¤t->sighand->siglock); |
| 832 | |
| 833 | return ret; |
| 834 | } |
| 835 | |
| 836 | #ifdef CONFIG_SECCOMP_FILTER |
| 837 | /** |
| 838 | * seccomp_set_mode_filter: internal function for setting seccomp filter |
| 839 | * @flags: flags to change filter behavior |
| 840 | * @filter: struct sock_fprog containing filter |
| 841 | * |
| 842 | * This function may be called repeatedly to install additional filters. |
| 843 | * Every filter successfully installed will be evaluated (in reverse order) |
| 844 | * for each system call the task makes. |
| 845 | * |
| 846 | * Once current->seccomp.mode is non-zero, it may not be changed. |
| 847 | * |
| 848 | * Returns 0 on success or -EINVAL on failure. |
| 849 | */ |
| 850 | static long seccomp_set_mode_filter(unsigned int flags, |
| 851 | const char __user *filter) |
| 852 | { |
| 853 | const unsigned long seccomp_mode = SECCOMP_MODE_FILTER; |
| 854 | struct seccomp_filter *prepared = NULL; |
| 855 | long ret = -EINVAL; |
| 856 | |
| 857 | /* Validate flags. */ |
| 858 | if (flags & ~SECCOMP_FILTER_FLAG_MASK) |
| 859 | return -EINVAL; |
| 860 | |
| 861 | /* Prepare the new filter before holding any locks. */ |
| 862 | prepared = seccomp_prepare_user_filter(filter); |
| 863 | if (IS_ERR(prepared)) |
| 864 | return PTR_ERR(prepared); |
| 865 | |
| 866 | /* |
| 867 | * Make sure we cannot change seccomp or nnp state via TSYNC |
| 868 | * while another thread is in the middle of calling exec. |
| 869 | */ |
| 870 | if (flags & SECCOMP_FILTER_FLAG_TSYNC && |
| 871 | mutex_lock_killable(¤t->signal->cred_guard_mutex)) |
| 872 | goto out_free; |
| 873 | |
| 874 | spin_lock_irq(¤t->sighand->siglock); |
| 875 | |
| 876 | if (!seccomp_may_assign_mode(seccomp_mode)) |
| 877 | goto out; |
| 878 | |
| 879 | ret = seccomp_attach_filter(flags, prepared); |
| 880 | if (ret) |
| 881 | goto out; |
| 882 | /* Do not free the successfully attached filter. */ |
| 883 | prepared = NULL; |
| 884 | |
| 885 | seccomp_assign_mode(current, seccomp_mode, flags); |
| 886 | out: |
| 887 | spin_unlock_irq(¤t->sighand->siglock); |
| 888 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) |
| 889 | mutex_unlock(¤t->signal->cred_guard_mutex); |
| 890 | out_free: |
| 891 | seccomp_filter_free(prepared); |
| 892 | return ret; |
| 893 | } |
| 894 | #else |
| 895 | static inline long seccomp_set_mode_filter(unsigned int flags, |
| 896 | const char __user *filter) |
| 897 | { |
| 898 | return -EINVAL; |
| 899 | } |
| 900 | #endif |
| 901 | |
| 902 | static long seccomp_get_action_avail(const char __user *uaction) |
| 903 | { |
| 904 | u32 action; |
| 905 | |
| 906 | if (copy_from_user(&action, uaction, sizeof(action))) |
| 907 | return -EFAULT; |
| 908 | |
| 909 | switch (action) { |
| 910 | case SECCOMP_RET_KILL_PROCESS: |
| 911 | case SECCOMP_RET_KILL_THREAD: |
| 912 | case SECCOMP_RET_TRAP: |
| 913 | case SECCOMP_RET_ERRNO: |
| 914 | case SECCOMP_RET_TRACE: |
| 915 | case SECCOMP_RET_LOG: |
| 916 | case SECCOMP_RET_ALLOW: |
| 917 | break; |
| 918 | default: |
| 919 | return -EOPNOTSUPP; |
| 920 | } |
| 921 | |
| 922 | return 0; |
| 923 | } |
| 924 | |
| 925 | /* Common entry point for both prctl and syscall. */ |
| 926 | static long do_seccomp(unsigned int op, unsigned int flags, |
| 927 | const char __user *uargs) |
| 928 | { |
| 929 | switch (op) { |
| 930 | case SECCOMP_SET_MODE_STRICT: |
| 931 | if (flags != 0 || uargs != NULL) |
| 932 | return -EINVAL; |
| 933 | return seccomp_set_mode_strict(); |
| 934 | case SECCOMP_SET_MODE_FILTER: |
| 935 | return seccomp_set_mode_filter(flags, uargs); |
| 936 | case SECCOMP_GET_ACTION_AVAIL: |
| 937 | if (flags != 0) |
| 938 | return -EINVAL; |
| 939 | |
| 940 | return seccomp_get_action_avail(uargs); |
| 941 | default: |
| 942 | return -EINVAL; |
| 943 | } |
| 944 | } |
| 945 | |
| 946 | SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags, |
| 947 | const char __user *, uargs) |
| 948 | { |
| 949 | return do_seccomp(op, flags, uargs); |
| 950 | } |
| 951 | |
| 952 | /** |
| 953 | * prctl_set_seccomp: configures current->seccomp.mode |
| 954 | * @seccomp_mode: requested mode to use |
| 955 | * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER |
| 956 | * |
| 957 | * Returns 0 on success or -EINVAL on failure. |
| 958 | */ |
| 959 | long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter) |
| 960 | { |
| 961 | unsigned int op; |
| 962 | char __user *uargs; |
| 963 | |
| 964 | switch (seccomp_mode) { |
| 965 | case SECCOMP_MODE_STRICT: |
| 966 | op = SECCOMP_SET_MODE_STRICT; |
| 967 | /* |
| 968 | * Setting strict mode through prctl always ignored filter, |
| 969 | * so make sure it is always NULL here to pass the internal |
| 970 | * check in do_seccomp(). |
| 971 | */ |
| 972 | uargs = NULL; |
| 973 | break; |
| 974 | case SECCOMP_MODE_FILTER: |
| 975 | op = SECCOMP_SET_MODE_FILTER; |
| 976 | uargs = filter; |
| 977 | break; |
| 978 | default: |
| 979 | return -EINVAL; |
| 980 | } |
| 981 | |
| 982 | /* prctl interface doesn't have flags, so they are always zero. */ |
| 983 | return do_seccomp(op, 0, uargs); |
| 984 | } |
| 985 | |
| 986 | #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE) |
| 987 | static struct seccomp_filter *get_nth_filter(struct task_struct *task, |
| 988 | unsigned long filter_off) |
| 989 | { |
| 990 | struct seccomp_filter *orig, *filter; |
| 991 | unsigned long count; |
| 992 | |
| 993 | /* |
| 994 | * Note: this is only correct because the caller should be the (ptrace) |
| 995 | * tracer of the task, otherwise lock_task_sighand is needed. |
| 996 | */ |
| 997 | spin_lock_irq(&task->sighand->siglock); |
| 998 | |
| 999 | if (task->seccomp.mode != SECCOMP_MODE_FILTER) { |
| 1000 | spin_unlock_irq(&task->sighand->siglock); |
| 1001 | return ERR_PTR(-EINVAL); |
| 1002 | } |
| 1003 | |
| 1004 | orig = task->seccomp.filter; |
| 1005 | __get_seccomp_filter(orig); |
| 1006 | spin_unlock_irq(&task->sighand->siglock); |
| 1007 | |
| 1008 | count = 0; |
| 1009 | for (filter = orig; filter; filter = filter->prev) |
| 1010 | count++; |
| 1011 | |
| 1012 | if (filter_off >= count) { |
| 1013 | filter = ERR_PTR(-ENOENT); |
| 1014 | goto out; |
| 1015 | } |
| 1016 | |
| 1017 | count -= filter_off; |
| 1018 | for (filter = orig; filter && count > 1; filter = filter->prev) |
| 1019 | count--; |
| 1020 | |
| 1021 | if (WARN_ON(count != 1 || !filter)) { |
| 1022 | filter = ERR_PTR(-ENOENT); |
| 1023 | goto out; |
| 1024 | } |
| 1025 | |
| 1026 | __get_seccomp_filter(filter); |
| 1027 | |
| 1028 | out: |
| 1029 | __put_seccomp_filter(orig); |
| 1030 | return filter; |
| 1031 | } |
| 1032 | |
| 1033 | long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, |
| 1034 | void __user *data) |
| 1035 | { |
| 1036 | struct seccomp_filter *filter; |
| 1037 | struct sock_fprog_kern *fprog; |
| 1038 | long ret; |
| 1039 | |
| 1040 | if (!capable(CAP_SYS_ADMIN) || |
| 1041 | current->seccomp.mode != SECCOMP_MODE_DISABLED) { |
| 1042 | return -EACCES; |
| 1043 | } |
| 1044 | |
| 1045 | filter = get_nth_filter(task, filter_off); |
| 1046 | if (IS_ERR(filter)) |
| 1047 | return PTR_ERR(filter); |
| 1048 | |
| 1049 | fprog = filter->prog->orig_prog; |
| 1050 | if (!fprog) { |
| 1051 | /* This must be a new non-cBPF filter, since we save |
| 1052 | * every cBPF filter's orig_prog above when |
| 1053 | * CONFIG_CHECKPOINT_RESTORE is enabled. |
| 1054 | */ |
| 1055 | ret = -EMEDIUMTYPE; |
| 1056 | goto out; |
| 1057 | } |
| 1058 | |
| 1059 | ret = fprog->len; |
| 1060 | if (!data) |
| 1061 | goto out; |
| 1062 | |
| 1063 | if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog))) |
| 1064 | ret = -EFAULT; |
| 1065 | |
| 1066 | out: |
| 1067 | __put_seccomp_filter(filter); |
| 1068 | return ret; |
| 1069 | } |
| 1070 | |
| 1071 | long seccomp_get_metadata(struct task_struct *task, |
| 1072 | unsigned long size, void __user *data) |
| 1073 | { |
| 1074 | long ret; |
| 1075 | struct seccomp_filter *filter; |
| 1076 | struct seccomp_metadata kmd = {}; |
| 1077 | |
| 1078 | if (!capable(CAP_SYS_ADMIN) || |
| 1079 | current->seccomp.mode != SECCOMP_MODE_DISABLED) { |
| 1080 | return -EACCES; |
| 1081 | } |
| 1082 | |
| 1083 | size = min_t(unsigned long, size, sizeof(kmd)); |
| 1084 | |
| 1085 | if (size < sizeof(kmd.filter_off)) |
| 1086 | return -EINVAL; |
| 1087 | |
| 1088 | if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off))) |
| 1089 | return -EFAULT; |
| 1090 | |
| 1091 | filter = get_nth_filter(task, kmd.filter_off); |
| 1092 | if (IS_ERR(filter)) |
| 1093 | return PTR_ERR(filter); |
| 1094 | |
| 1095 | if (filter->log) |
| 1096 | kmd.flags |= SECCOMP_FILTER_FLAG_LOG; |
| 1097 | |
| 1098 | ret = size; |
| 1099 | if (copy_to_user(data, &kmd, size)) |
| 1100 | ret = -EFAULT; |
| 1101 | |
| 1102 | __put_seccomp_filter(filter); |
| 1103 | return ret; |
| 1104 | } |
| 1105 | #endif |
| 1106 | |
| 1107 | #ifdef CONFIG_SYSCTL |
| 1108 | |
| 1109 | /* Human readable action names for friendly sysctl interaction */ |
| 1110 | #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process" |
| 1111 | #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread" |
| 1112 | #define SECCOMP_RET_TRAP_NAME "trap" |
| 1113 | #define SECCOMP_RET_ERRNO_NAME "errno" |
| 1114 | #define SECCOMP_RET_TRACE_NAME "trace" |
| 1115 | #define SECCOMP_RET_LOG_NAME "log" |
| 1116 | #define SECCOMP_RET_ALLOW_NAME "allow" |
| 1117 | |
| 1118 | static const char seccomp_actions_avail[] = |
| 1119 | SECCOMP_RET_KILL_PROCESS_NAME " " |
| 1120 | SECCOMP_RET_KILL_THREAD_NAME " " |
| 1121 | SECCOMP_RET_TRAP_NAME " " |
| 1122 | SECCOMP_RET_ERRNO_NAME " " |
| 1123 | SECCOMP_RET_TRACE_NAME " " |
| 1124 | SECCOMP_RET_LOG_NAME " " |
| 1125 | SECCOMP_RET_ALLOW_NAME; |
| 1126 | |
| 1127 | struct seccomp_log_name { |
| 1128 | u32 log; |
| 1129 | const char *name; |
| 1130 | }; |
| 1131 | |
| 1132 | static const struct seccomp_log_name seccomp_log_names[] = { |
| 1133 | { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME }, |
| 1134 | { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME }, |
| 1135 | { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME }, |
| 1136 | { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME }, |
| 1137 | { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME }, |
| 1138 | { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME }, |
| 1139 | { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME }, |
| 1140 | { } |
| 1141 | }; |
| 1142 | |
| 1143 | static bool seccomp_names_from_actions_logged(char *names, size_t size, |
| 1144 | u32 actions_logged, |
| 1145 | const char *sep) |
| 1146 | { |
| 1147 | const struct seccomp_log_name *cur; |
| 1148 | bool append_sep = false; |
| 1149 | |
| 1150 | for (cur = seccomp_log_names; cur->name && size; cur++) { |
| 1151 | ssize_t ret; |
| 1152 | |
| 1153 | if (!(actions_logged & cur->log)) |
| 1154 | continue; |
| 1155 | |
| 1156 | if (append_sep) { |
| 1157 | ret = strscpy(names, sep, size); |
| 1158 | if (ret < 0) |
| 1159 | return false; |
| 1160 | |
| 1161 | names += ret; |
| 1162 | size -= ret; |
| 1163 | } else |
| 1164 | append_sep = true; |
| 1165 | |
| 1166 | ret = strscpy(names, cur->name, size); |
| 1167 | if (ret < 0) |
| 1168 | return false; |
| 1169 | |
| 1170 | names += ret; |
| 1171 | size -= ret; |
| 1172 | } |
| 1173 | |
| 1174 | return true; |
| 1175 | } |
| 1176 | |
| 1177 | static bool seccomp_action_logged_from_name(u32 *action_logged, |
| 1178 | const char *name) |
| 1179 | { |
| 1180 | const struct seccomp_log_name *cur; |
| 1181 | |
| 1182 | for (cur = seccomp_log_names; cur->name; cur++) { |
| 1183 | if (!strcmp(cur->name, name)) { |
| 1184 | *action_logged = cur->log; |
| 1185 | return true; |
| 1186 | } |
| 1187 | } |
| 1188 | |
| 1189 | return false; |
| 1190 | } |
| 1191 | |
| 1192 | static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names) |
| 1193 | { |
| 1194 | char *name; |
| 1195 | |
| 1196 | *actions_logged = 0; |
| 1197 | while ((name = strsep(&names, " ")) && *name) { |
| 1198 | u32 action_logged = 0; |
| 1199 | |
| 1200 | if (!seccomp_action_logged_from_name(&action_logged, name)) |
| 1201 | return false; |
| 1202 | |
| 1203 | *actions_logged |= action_logged; |
| 1204 | } |
| 1205 | |
| 1206 | return true; |
| 1207 | } |
| 1208 | |
| 1209 | static int read_actions_logged(struct ctl_table *ro_table, void __user *buffer, |
| 1210 | size_t *lenp, loff_t *ppos) |
| 1211 | { |
| 1212 | char names[sizeof(seccomp_actions_avail)]; |
| 1213 | struct ctl_table table; |
| 1214 | |
| 1215 | memset(names, 0, sizeof(names)); |
| 1216 | |
| 1217 | if (!seccomp_names_from_actions_logged(names, sizeof(names), |
| 1218 | seccomp_actions_logged, " ")) |
| 1219 | return -EINVAL; |
| 1220 | |
| 1221 | table = *ro_table; |
| 1222 | table.data = names; |
| 1223 | table.maxlen = sizeof(names); |
| 1224 | return proc_dostring(&table, 0, buffer, lenp, ppos); |
| 1225 | } |
| 1226 | |
| 1227 | static int write_actions_logged(struct ctl_table *ro_table, void __user *buffer, |
| 1228 | size_t *lenp, loff_t *ppos, u32 *actions_logged) |
| 1229 | { |
| 1230 | char names[sizeof(seccomp_actions_avail)]; |
| 1231 | struct ctl_table table; |
| 1232 | int ret; |
| 1233 | |
| 1234 | if (!capable(CAP_SYS_ADMIN)) |
| 1235 | return -EPERM; |
| 1236 | |
| 1237 | memset(names, 0, sizeof(names)); |
| 1238 | |
| 1239 | table = *ro_table; |
| 1240 | table.data = names; |
| 1241 | table.maxlen = sizeof(names); |
| 1242 | ret = proc_dostring(&table, 1, buffer, lenp, ppos); |
| 1243 | if (ret) |
| 1244 | return ret; |
| 1245 | |
| 1246 | if (!seccomp_actions_logged_from_names(actions_logged, table.data)) |
| 1247 | return -EINVAL; |
| 1248 | |
| 1249 | if (*actions_logged & SECCOMP_LOG_ALLOW) |
| 1250 | return -EINVAL; |
| 1251 | |
| 1252 | seccomp_actions_logged = *actions_logged; |
| 1253 | return 0; |
| 1254 | } |
| 1255 | |
| 1256 | static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged, |
| 1257 | int ret) |
| 1258 | { |
| 1259 | char names[sizeof(seccomp_actions_avail)]; |
| 1260 | char old_names[sizeof(seccomp_actions_avail)]; |
| 1261 | const char *new = names; |
| 1262 | const char *old = old_names; |
| 1263 | |
| 1264 | if (!audit_enabled) |
| 1265 | return; |
| 1266 | |
| 1267 | memset(names, 0, sizeof(names)); |
| 1268 | memset(old_names, 0, sizeof(old_names)); |
| 1269 | |
| 1270 | if (ret) |
| 1271 | new = "?"; |
| 1272 | else if (!actions_logged) |
| 1273 | new = "(none)"; |
| 1274 | else if (!seccomp_names_from_actions_logged(names, sizeof(names), |
| 1275 | actions_logged, ",")) |
| 1276 | new = "?"; |
| 1277 | |
| 1278 | if (!old_actions_logged) |
| 1279 | old = "(none)"; |
| 1280 | else if (!seccomp_names_from_actions_logged(old_names, |
| 1281 | sizeof(old_names), |
| 1282 | old_actions_logged, ",")) |
| 1283 | old = "?"; |
| 1284 | |
| 1285 | return audit_seccomp_actions_logged(new, old, !ret); |
| 1286 | } |
| 1287 | |
| 1288 | static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write, |
| 1289 | void __user *buffer, size_t *lenp, |
| 1290 | loff_t *ppos) |
| 1291 | { |
| 1292 | int ret; |
| 1293 | |
| 1294 | if (write) { |
| 1295 | u32 actions_logged = 0; |
| 1296 | u32 old_actions_logged = seccomp_actions_logged; |
| 1297 | |
| 1298 | ret = write_actions_logged(ro_table, buffer, lenp, ppos, |
| 1299 | &actions_logged); |
| 1300 | audit_actions_logged(actions_logged, old_actions_logged, ret); |
| 1301 | } else |
| 1302 | ret = read_actions_logged(ro_table, buffer, lenp, ppos); |
| 1303 | |
| 1304 | return ret; |
| 1305 | } |
| 1306 | |
| 1307 | static struct ctl_path seccomp_sysctl_path[] = { |
| 1308 | { .procname = "kernel", }, |
| 1309 | { .procname = "seccomp", }, |
| 1310 | { } |
| 1311 | }; |
| 1312 | |
| 1313 | static struct ctl_table seccomp_sysctl_table[] = { |
| 1314 | { |
| 1315 | .procname = "actions_avail", |
| 1316 | .data = (void *) &seccomp_actions_avail, |
| 1317 | .maxlen = sizeof(seccomp_actions_avail), |
| 1318 | .mode = 0444, |
| 1319 | .proc_handler = proc_dostring, |
| 1320 | }, |
| 1321 | { |
| 1322 | .procname = "actions_logged", |
| 1323 | .mode = 0644, |
| 1324 | .proc_handler = seccomp_actions_logged_handler, |
| 1325 | }, |
| 1326 | { } |
| 1327 | }; |
| 1328 | |
| 1329 | static int __init seccomp_sysctl_init(void) |
| 1330 | { |
| 1331 | struct ctl_table_header *hdr; |
| 1332 | |
| 1333 | hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table); |
| 1334 | if (!hdr) |
| 1335 | pr_warn("seccomp: sysctl registration failed\n"); |
| 1336 | else |
| 1337 | kmemleak_not_leak(hdr); |
| 1338 | |
| 1339 | return 0; |
| 1340 | } |
| 1341 | |
| 1342 | device_initcall(seccomp_sysctl_init) |
| 1343 | |
| 1344 | #endif /* CONFIG_SYSCTL */ |