| 1 | |
| 2 | |
| 3 | * linux/kernel/seccomp.c
|
| 4 | *
|
| 5 | * Copyright 2004-2005 Andrea Arcangeli <[email protected]>
|
| 6 | *
|
| 7 | * Copyright (C) 2012 Google, Inc.
|
| 8 | * Will Drewry <[email protected]>
|
| 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 |
|
| 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 |
|
| 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 |
|
| 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 |
|
| 194 | struct seccomp_filter *f =
|
| 195 | READ_ONCE(current->seccomp.filter);
|
| 196 |
|
| 197 |
|
| 198 | if (unlikely(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
|
| 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 |
|
| 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 |
|
| 254 | static int is_ancestor(struct seccomp_filter *parent,
|
| 255 | struct seccomp_filter *child)
|
| 256 | {
|
| 257 |
|
| 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 |
|
| 283 | caller = current;
|
| 284 | for_each_thread(caller, thread) {
|
| 285 | pid_t failed;
|
| 286 |
|
| 287 |
|
| 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 |
|
| 298 | failed = task_pid_vnr(thread);
|
| 299 |
|
| 300 | if (unlikely(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 |
|
| 324 | caller = current;
|
| 325 | for_each_thread(caller, thread) {
|
| 326 |
|
| 327 | if (thread == caller)
|
| 328 | continue;
|
| 329 |
|
| 330 |
|
| 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 |
|
| 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
|
| 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 |
|
| 453 | total_insns = filter->prog->len;
|
| 454 | for (walker = current->seccomp.filter; walker; walker = walker->prev)
|
| 455 | total_insns += walker->prog->len + 4;
|
| 456 | if (total_insns > MAX_INSNS_PER_PATH)
|
| 457 | return -ENOMEM;
|
| 458 |
|
| 459 |
|
| 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 |
|
| 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 |
|
| 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 |
|
| 489 | refcount_inc(&filter->usage);
|
| 490 | }
|
| 491 |
|
| 492 |
|
| 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 |
|
| 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 |
|
| 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(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 siginfo info;
|
| 546 | seccomp_init_siginfo(&info, syscall, reason);
|
| 547 | force_sig_info(SIGSYS, &info, current);
|
| 548 | }
|
| 549 | #endif
|
| 550 |
|
| 551 |
|
| 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 | * Force an audit message to be emitted when the action is RET_KILL_*,
|
| 597 | * RET_LOG, or the FILTER_FLAG_LOG bit was set and the action is
|
| 598 | * allowed to be logged by the admin.
|
| 599 |
|
| 600 | if (log)
|
| 601 | return __audit_seccomp(syscall, signr, action);
|
| 602 |
|
| 603 | |
| 604 | * Let the audit subsystem decide if the action should be audited based
|
| 605 | * on whether the current task itself is being audited.
|
| 606 |
|
| 607 | return audit_seccomp(syscall, signr, action);
|
| 608 | }
|
| 609 |
|
| 610 | |
| 611 | * Secure computing mode 1 allows only read/write/exit/sigreturn.
|
| 612 | * To be fully secure this must be combined with rlimit
|
| 613 | * to limit the stack allocations too.
|
| 614 |
|
| 615 | static const int mode1_syscalls[] = {
|
| 616 | __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
|
| 617 | 0,
|
| 618 | };
|
| 619 |
|
| 620 | static void __secure_computing_strict(int this_syscall)
|
| 621 | {
|
| 622 | const int *syscall_whitelist = mode1_syscalls;
|
| 623 | #ifdef CONFIG_COMPAT
|
| 624 | if (in_compat_syscall())
|
| 625 | syscall_whitelist = get_compat_mode1_syscalls();
|
| 626 | #endif
|
| 627 | do {
|
| 628 | if (*syscall_whitelist == this_syscall)
|
| 629 | return;
|
| 630 | } while (*++syscall_whitelist);
|
| 631 |
|
| 632 | #ifdef SECCOMP_DEBUG
|
| 633 | dump_stack();
|
| 634 | #endif
|
| 635 | seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
|
| 636 | do_exit(SIGKILL);
|
| 637 | }
|
| 638 |
|
| 639 | #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
|
| 640 | void secure_computing_strict(int this_syscall)
|
| 641 | {
|
| 642 | int mode = current->seccomp.mode;
|
| 643 |
|
| 644 | if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
|
| 645 | unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
|
| 646 | return;
|
| 647 |
|
| 648 | if (mode == SECCOMP_MODE_DISABLED)
|
| 649 | return;
|
| 650 | else if (mode == SECCOMP_MODE_STRICT)
|
| 651 | __secure_computing_strict(this_syscall);
|
| 652 | else
|
| 653 | BUG();
|
| 654 | }
|
| 655 | #else
|
| 656 |
|
| 657 | #ifdef CONFIG_SECCOMP_FILTER
|
| 658 | static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
|
| 659 | const bool recheck_after_trace)
|
| 660 | {
|
| 661 | u32 filter_ret, action;
|
| 662 | struct seccomp_filter *match = NULL;
|
| 663 | int data;
|
| 664 |
|
| 665 | |
| 666 | * Make sure that any changes to mode from another thread have
|
| 667 | * been seen after TIF_SECCOMP was seen.
|
| 668 |
|
| 669 | rmb();
|
| 670 |
|
| 671 | filter_ret = seccomp_run_filters(sd, &match);
|
| 672 | data = filter_ret & SECCOMP_RET_DATA;
|
| 673 | action = filter_ret & SECCOMP_RET_ACTION_FULL;
|
| 674 |
|
| 675 | switch (action) {
|
| 676 | case SECCOMP_RET_ERRNO:
|
| 677 |
|
| 678 | if (data > MAX_ERRNO)
|
| 679 | data = MAX_ERRNO;
|
| 680 | syscall_set_return_value(current, task_pt_regs(current),
|
| 681 | -data, 0);
|
| 682 | goto skip;
|
| 683 |
|
| 684 | case SECCOMP_RET_TRAP:
|
| 685 |
|
| 686 | syscall_rollback(current, task_pt_regs(current));
|
| 687 |
|
| 688 | seccomp_send_sigsys(this_syscall, data);
|
| 689 | goto skip;
|
| 690 |
|
| 691 | case SECCOMP_RET_TRACE:
|
| 692 |
|
| 693 | if (recheck_after_trace)
|
| 694 | return 0;
|
| 695 |
|
| 696 |
|
| 697 | if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
|
| 698 | syscall_set_return_value(current,
|
| 699 | task_pt_regs(current),
|
| 700 | -ENOSYS, 0);
|
| 701 | goto skip;
|
| 702 | }
|
| 703 |
|
| 704 |
|
| 705 | ptrace_event(PTRACE_EVENT_SECCOMP, data);
|
| 706 | |
| 707 | * The delivery of a fatal signal during event
|
| 708 | * notification may silently skip tracer notification,
|
| 709 | * which could leave us with a potentially unmodified
|
| 710 | * syscall that the tracer would have liked to have
|
| 711 | * changed. Since the process is about to die, we just
|
| 712 | * force the syscall to be skipped and let the signal
|
| 713 | * kill the process and correctly handle any tracer exit
|
| 714 | * notifications.
|
| 715 |
|
| 716 | if (fatal_signal_pending(current))
|
| 717 | goto skip;
|
| 718 |
|
| 719 | this_syscall = syscall_get_nr(current, task_pt_regs(current));
|
| 720 | if (this_syscall < 0)
|
| 721 | goto skip;
|
| 722 |
|
| 723 | |
| 724 | * Recheck the syscall, since it may have changed. This
|
| 725 | * intentionally uses a NULL struct seccomp_data to force
|
| 726 | * a reload of all registers. This does not goto skip since
|
| 727 | * a skip would have already been reported.
|
| 728 |
|
| 729 | if (__seccomp_filter(this_syscall, NULL, true))
|
| 730 | return -1;
|
| 731 |
|
| 732 | return 0;
|
| 733 |
|
| 734 | case SECCOMP_RET_LOG:
|
| 735 | seccomp_log(this_syscall, 0, action, true);
|
| 736 | return 0;
|
| 737 |
|
| 738 | case SECCOMP_RET_ALLOW:
|
| 739 | |
| 740 | * Note that the "match" filter will always be NULL for
|
| 741 | * this action since SECCOMP_RET_ALLOW is the starting
|
| 742 | * state in seccomp_run_filters().
|
| 743 |
|
| 744 | return 0;
|
| 745 |
|
| 746 | case SECCOMP_RET_KILL_THREAD:
|
| 747 | case SECCOMP_RET_KILL_PROCESS:
|
| 748 | default:
|
| 749 | seccomp_log(this_syscall, SIGSYS, action, true);
|
| 750 |
|
| 751 | if (action == SECCOMP_RET_KILL_PROCESS ||
|
| 752 | get_nr_threads(current) == 1) {
|
| 753 | siginfo_t info;
|
| 754 |
|
| 755 |
|
| 756 | syscall_rollback(current, task_pt_regs(current));
|
| 757 |
|
| 758 | seccomp_init_siginfo(&info, this_syscall, data);
|
| 759 | do_coredump(&info);
|
| 760 | }
|
| 761 | if (action == SECCOMP_RET_KILL_PROCESS)
|
| 762 | do_group_exit(SIGSYS);
|
| 763 | else
|
| 764 | do_exit(SIGSYS);
|
| 765 | }
|
| 766 |
|
| 767 | unreachable();
|
| 768 |
|
| 769 | skip:
|
| 770 | seccomp_log(this_syscall, 0, action, match ? match->log : false);
|
| 771 | return -1;
|
| 772 | }
|
| 773 | #else
|
| 774 | static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
|
| 775 | const bool recheck_after_trace)
|
| 776 | {
|
| 777 | BUG();
|
| 778 | }
|
| 779 | #endif
|
| 780 |
|
| 781 | int __secure_computing(const struct seccomp_data *sd)
|
| 782 | {
|
| 783 | int mode = current->seccomp.mode;
|
| 784 | int this_syscall;
|
| 785 |
|
| 786 | if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
|
| 787 | unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
|
| 788 | return 0;
|
| 789 |
|
| 790 | this_syscall = sd ? sd->nr :
|
| 791 | syscall_get_nr(current, task_pt_regs(current));
|
| 792 |
|
| 793 | switch (mode) {
|
| 794 | case SECCOMP_MODE_STRICT:
|
| 795 | __secure_computing_strict(this_syscall);
|
| 796 | return 0;
|
| 797 | case SECCOMP_MODE_FILTER:
|
| 798 | return __seccomp_filter(this_syscall, sd, false);
|
| 799 | default:
|
| 800 | BUG();
|
| 801 | }
|
| 802 | }
|
| 803 | #endif
|
| 804 |
|
| 805 | long prctl_get_seccomp(void)
|
| 806 | {
|
| 807 | return current->seccomp.mode;
|
| 808 | }
|
| 809 |
|
| 810 | |
| 811 | * seccomp_set_mode_strict: internal function for setting strict seccomp
|
| 812 | *
|
| 813 | * Once current->seccomp.mode is non-zero, it may not be changed.
|
| 814 | *
|
| 815 | * Returns 0 on success or -EINVAL on failure.
|
| 816 |
|
| 817 | static long seccomp_set_mode_strict(void)
|
| 818 | {
|
| 819 | const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
|
| 820 | long ret = -EINVAL;
|
| 821 |
|
| 822 | spin_lock_irq(¤t->sighand->siglock);
|
| 823 |
|
| 824 | if (!seccomp_may_assign_mode(seccomp_mode))
|
| 825 | goto out;
|
| 826 |
|
| 827 | #ifdef TIF_NOTSC
|
| 828 | disable_TSC();
|
| 829 | #endif
|
| 830 | seccomp_assign_mode(current, seccomp_mode, 0);
|
| 831 | ret = 0;
|
| 832 |
|
| 833 | out:
|
| 834 | spin_unlock_irq(¤t->sighand->siglock);
|
| 835 |
|
| 836 | return ret;
|
| 837 | }
|
| 838 |
|
| 839 | #ifdef CONFIG_SECCOMP_FILTER
|
| 840 | |
| 841 | * seccomp_set_mode_filter: internal function for setting seccomp filter
|
| 842 | * @flags: flags to change filter behavior
|
| 843 | * @filter: struct sock_fprog containing filter
|
| 844 | *
|
| 845 | * This function may be called repeatedly to install additional filters.
|
| 846 | * Every filter successfully installed will be evaluated (in reverse order)
|
| 847 | * for each system call the task makes.
|
| 848 | *
|
| 849 | * Once current->seccomp.mode is non-zero, it may not be changed.
|
| 850 | *
|
| 851 | * Returns 0 on success or -EINVAL on failure.
|
| 852 |
|
| 853 | static long seccomp_set_mode_filter(unsigned int flags,
|
| 854 | const char __user *filter)
|
| 855 | {
|
| 856 | const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
|
| 857 | struct seccomp_filter *prepared = NULL;
|
| 858 | long ret = -EINVAL;
|
| 859 |
|
| 860 |
|
| 861 | if (flags & ~SECCOMP_FILTER_FLAG_MASK)
|
| 862 | return -EINVAL;
|
| 863 |
|
| 864 |
|
| 865 | prepared = seccomp_prepare_user_filter(filter);
|
| 866 | if (IS_ERR(prepared))
|
| 867 | return PTR_ERR(prepared);
|
| 868 |
|
| 869 | |
| 870 | * Make sure we cannot change seccomp or nnp state via TSYNC
|
| 871 | * while another thread is in the middle of calling exec.
|
| 872 |
|
| 873 | if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
|
| 874 | mutex_lock_killable(¤t->signal->cred_guard_mutex))
|
| 875 | goto out_free;
|
| 876 |
|
| 877 | spin_lock_irq(¤t->sighand->siglock);
|
| 878 |
|
| 879 | if (!seccomp_may_assign_mode(seccomp_mode))
|
| 880 | goto out;
|
| 881 |
|
| 882 | ret = seccomp_attach_filter(flags, prepared);
|
| 883 | if (ret)
|
| 884 | goto out;
|
| 885 |
|
| 886 | prepared = NULL;
|
| 887 |
|
| 888 | seccomp_assign_mode(current, seccomp_mode, flags);
|
| 889 | out:
|
| 890 | spin_unlock_irq(¤t->sighand->siglock);
|
| 891 | if (flags & SECCOMP_FILTER_FLAG_TSYNC)
|
| 892 | mutex_unlock(¤t->signal->cred_guard_mutex);
|
| 893 | out_free:
|
| 894 | seccomp_filter_free(prepared);
|
| 895 | return ret;
|
| 896 | }
|
| 897 | #else
|
| 898 | static inline long seccomp_set_mode_filter(unsigned int flags,
|
| 899 | const char __user *filter)
|
| 900 | {
|
| 901 | return -EINVAL;
|
| 902 | }
|
| 903 | #endif
|
| 904 |
|
| 905 | static long seccomp_get_action_avail(const char __user *uaction)
|
| 906 | {
|
| 907 | u32 action;
|
| 908 |
|
| 909 | if (copy_from_user(&action, uaction, sizeof(action)))
|
| 910 | return -EFAULT;
|
| 911 |
|
| 912 | switch (action) {
|
| 913 | case SECCOMP_RET_KILL_PROCESS:
|
| 914 | case SECCOMP_RET_KILL_THREAD:
|
| 915 | case SECCOMP_RET_TRAP:
|
| 916 | case SECCOMP_RET_ERRNO:
|
| 917 | case SECCOMP_RET_TRACE:
|
| 918 | case SECCOMP_RET_LOG:
|
| 919 | case SECCOMP_RET_ALLOW:
|
| 920 | break;
|
| 921 | default:
|
| 922 | return -EOPNOTSUPP;
|
| 923 | }
|
| 924 |
|
| 925 | return 0;
|
| 926 | }
|
| 927 |
|
| 928 |
|
| 929 | static long do_seccomp(unsigned int op, unsigned int flags,
|
| 930 | const char __user *uargs)
|
| 931 | {
|
| 932 | switch (op) {
|
| 933 | case SECCOMP_SET_MODE_STRICT:
|
| 934 | if (flags != 0 || uargs != NULL)
|
| 935 | return -EINVAL;
|
| 936 | return seccomp_set_mode_strict();
|
| 937 | case SECCOMP_SET_MODE_FILTER:
|
| 938 | return seccomp_set_mode_filter(flags, uargs);
|
| 939 | case SECCOMP_GET_ACTION_AVAIL:
|
| 940 | if (flags != 0)
|
| 941 | return -EINVAL;
|
| 942 |
|
| 943 | return seccomp_get_action_avail(uargs);
|
| 944 | default:
|
| 945 | return -EINVAL;
|
| 946 | }
|
| 947 | }
|
| 948 |
|
| 949 | SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
|
| 950 | const char __user *, uargs)
|
| 951 | {
|
| 952 | return do_seccomp(op, flags, uargs);
|
| 953 | }
|
| 954 |
|
| 955 | |
| 956 | * prctl_set_seccomp: configures current->seccomp.mode
|
| 957 | * @seccomp_mode: requested mode to use
|
| 958 | * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
|
| 959 | *
|
| 960 | * Returns 0 on success or -EINVAL on failure.
|
| 961 |
|
| 962 | long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
|
| 963 | {
|
| 964 | unsigned int op;
|
| 965 | char __user *uargs;
|
| 966 |
|
| 967 | switch (seccomp_mode) {
|
| 968 | case SECCOMP_MODE_STRICT:
|
| 969 | op = SECCOMP_SET_MODE_STRICT;
|
| 970 | |
| 971 | * Setting strict mode through prctl always ignored filter,
|
| 972 | * so make sure it is always NULL here to pass the internal
|
| 973 | * check in do_seccomp().
|
| 974 |
|
| 975 | uargs = NULL;
|
| 976 | break;
|
| 977 | case SECCOMP_MODE_FILTER:
|
| 978 | op = SECCOMP_SET_MODE_FILTER;
|
| 979 | uargs = filter;
|
| 980 | break;
|
| 981 | default:
|
| 982 | return -EINVAL;
|
| 983 | }
|
| 984 |
|
| 985 |
|
| 986 | return do_seccomp(op, 0, uargs);
|
| 987 | }
|
| 988 |
|
| 989 | #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
|
| 990 | static struct seccomp_filter *get_nth_filter(struct task_struct *task,
|
| 991 | unsigned long filter_off)
|
| 992 | {
|
| 993 | struct seccomp_filter *orig, *filter;
|
| 994 | unsigned long count;
|
| 995 |
|
| 996 | |
| 997 | * Note: this is only correct because the caller should be the (ptrace)
|
| 998 | * tracer of the task, otherwise lock_task_sighand is needed.
|
| 999 |
|
| 1000 | spin_lock_irq(&task->sighand->siglock);
|
| 1001 |
|
| 1002 | if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
|
| 1003 | spin_unlock_irq(&task->sighand->siglock);
|
| 1004 | return ERR_PTR(-EINVAL);
|
| 1005 | }
|
| 1006 |
|
| 1007 | orig = task->seccomp.filter;
|
| 1008 | __get_seccomp_filter(orig);
|
| 1009 | spin_unlock_irq(&task->sighand->siglock);
|
| 1010 |
|
| 1011 | count = 0;
|
| 1012 | for (filter = orig; filter; filter = filter->prev)
|
| 1013 | count++;
|
| 1014 |
|
| 1015 | if (filter_off >= count) {
|
| 1016 | filter = ERR_PTR(-ENOENT);
|
| 1017 | goto out;
|
| 1018 | }
|
| 1019 |
|
| 1020 | count -= filter_off;
|
| 1021 | for (filter = orig; filter && count > 1; filter = filter->prev)
|
| 1022 | count--;
|
| 1023 |
|
| 1024 | if (WARN_ON(count != 1 || !filter)) {
|
| 1025 | filter = ERR_PTR(-ENOENT);
|
| 1026 | goto out;
|
| 1027 | }
|
| 1028 |
|
| 1029 | __get_seccomp_filter(filter);
|
| 1030 |
|
| 1031 | out:
|
| 1032 | __put_seccomp_filter(orig);
|
| 1033 | return filter;
|
| 1034 | }
|
| 1035 |
|
| 1036 | long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
|
| 1037 | void __user *data)
|
| 1038 | {
|
| 1039 | struct seccomp_filter *filter;
|
| 1040 | struct sock_fprog_kern *fprog;
|
| 1041 | long ret;
|
| 1042 |
|
| 1043 | if (!capable(CAP_SYS_ADMIN) ||
|
| 1044 | current->seccomp.mode != SECCOMP_MODE_DISABLED) {
|
| 1045 | return -EACCES;
|
| 1046 | }
|
| 1047 |
|
| 1048 | filter = get_nth_filter(task, filter_off);
|
| 1049 | if (IS_ERR(filter))
|
| 1050 | return PTR_ERR(filter);
|
| 1051 |
|
| 1052 | fprog = filter->prog->orig_prog;
|
| 1053 | if (!fprog) {
|
| 1054 | |
| 1055 | * every cBPF filter's orig_prog above when
|
| 1056 | * CONFIG_CHECKPOINT_RESTORE is enabled.
|
| 1057 |
|
| 1058 | ret = -EMEDIUMTYPE;
|
| 1059 | goto out;
|
| 1060 | }
|
| 1061 |
|
| 1062 | ret = fprog->len;
|
| 1063 | if (!data)
|
| 1064 | goto out;
|
| 1065 |
|
| 1066 | if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
|
| 1067 | ret = -EFAULT;
|
| 1068 |
|
| 1069 | out:
|
| 1070 | __put_seccomp_filter(filter);
|
| 1071 | return ret;
|
| 1072 | }
|
| 1073 |
|
| 1074 | long seccomp_get_metadata(struct task_struct *task,
|
| 1075 | unsigned long size, void __user *data)
|
| 1076 | {
|
| 1077 | long ret;
|
| 1078 | struct seccomp_filter *filter;
|
| 1079 | struct seccomp_metadata kmd = {};
|
| 1080 |
|
| 1081 | if (!capable(CAP_SYS_ADMIN) ||
|
| 1082 | current->seccomp.mode != SECCOMP_MODE_DISABLED) {
|
| 1083 | return -EACCES;
|
| 1084 | }
|
| 1085 |
|
| 1086 | size = min_t(unsigned long, size, sizeof(kmd));
|
| 1087 |
|
| 1088 | if (size < sizeof(kmd.filter_off))
|
| 1089 | return -EINVAL;
|
| 1090 |
|
| 1091 | if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
|
| 1092 | return -EFAULT;
|
| 1093 |
|
| 1094 | filter = get_nth_filter(task, kmd.filter_off);
|
| 1095 | if (IS_ERR(filter))
|
| 1096 | return PTR_ERR(filter);
|
| 1097 |
|
| 1098 | if (filter->log)
|
| 1099 | kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
|
| 1100 |
|
| 1101 | ret = size;
|
| 1102 | if (copy_to_user(data, &kmd, size))
|
| 1103 | ret = -EFAULT;
|
| 1104 |
|
| 1105 | __put_seccomp_filter(filter);
|
| 1106 | return ret;
|
| 1107 | }
|
| 1108 | #endif
|
| 1109 |
|
| 1110 | #ifdef CONFIG_SYSCTL
|
| 1111 |
|
| 1112 |
|
| 1113 | #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
|
| 1114 | #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
|
| 1115 | #define SECCOMP_RET_TRAP_NAME "trap"
|
| 1116 | #define SECCOMP_RET_ERRNO_NAME "errno"
|
| 1117 | #define SECCOMP_RET_TRACE_NAME "trace"
|
| 1118 | #define SECCOMP_RET_LOG_NAME "log"
|
| 1119 | #define SECCOMP_RET_ALLOW_NAME "allow"
|
| 1120 |
|
| 1121 | static const char seccomp_actions_avail[] =
|
| 1122 | SECCOMP_RET_KILL_PROCESS_NAME " "
|
| 1123 | SECCOMP_RET_KILL_THREAD_NAME " "
|
| 1124 | SECCOMP_RET_TRAP_NAME " "
|
| 1125 | SECCOMP_RET_ERRNO_NAME " "
|
| 1126 | SECCOMP_RET_TRACE_NAME " "
|
| 1127 | SECCOMP_RET_LOG_NAME " "
|
| 1128 | SECCOMP_RET_ALLOW_NAME;
|
| 1129 |
|
| 1130 | struct seccomp_log_name {
|
| 1131 | u32 log;
|
| 1132 | const char *name;
|
| 1133 | };
|
| 1134 |
|
| 1135 | static const struct seccomp_log_name seccomp_log_names[] = {
|
| 1136 | { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
|
| 1137 | { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
|
| 1138 | { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
|
| 1139 | { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
|
| 1140 | { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
|
| 1141 | { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
|
| 1142 | { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
|
| 1143 | { }
|
| 1144 | };
|
| 1145 |
|
| 1146 | static bool seccomp_names_from_actions_logged(char *names, size_t size,
|
| 1147 | u32 actions_logged)
|
| 1148 | {
|
| 1149 | const struct seccomp_log_name *cur;
|
| 1150 | bool append_space = false;
|
| 1151 |
|
| 1152 | for (cur = seccomp_log_names; cur->name && size; cur++) {
|
| 1153 | ssize_t ret;
|
| 1154 |
|
| 1155 | if (!(actions_logged & cur->log))
|
| 1156 | continue;
|
| 1157 |
|
| 1158 | if (append_space) {
|
| 1159 | ret = strscpy(names, " ", size);
|
| 1160 | if (ret < 0)
|
| 1161 | return false;
|
| 1162 |
|
| 1163 | names += ret;
|
| 1164 | size -= ret;
|
| 1165 | } else
|
| 1166 | append_space = true;
|
| 1167 |
|
| 1168 | ret = strscpy(names, cur->name, size);
|
| 1169 | if (ret < 0)
|
| 1170 | return false;
|
| 1171 |
|
| 1172 | names += ret;
|
| 1173 | size -= ret;
|
| 1174 | }
|
| 1175 |
|
| 1176 | return true;
|
| 1177 | }
|
| 1178 |
|
| 1179 | static bool seccomp_action_logged_from_name(u32 *action_logged,
|
| 1180 | const char *name)
|
| 1181 | {
|
| 1182 | const struct seccomp_log_name *cur;
|
| 1183 |
|
| 1184 | for (cur = seccomp_log_names; cur->name; cur++) {
|
| 1185 | if (!strcmp(cur->name, name)) {
|
| 1186 | *action_logged = cur->log;
|
| 1187 | return true;
|
| 1188 | }
|
| 1189 | }
|
| 1190 |
|
| 1191 | return false;
|
| 1192 | }
|
| 1193 |
|
| 1194 | static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
|
| 1195 | {
|
| 1196 | char *name;
|
| 1197 |
|
| 1198 | *actions_logged = 0;
|
| 1199 | while ((name = strsep(&names, " ")) && *name) {
|
| 1200 | u32 action_logged = 0;
|
| 1201 |
|
| 1202 | if (!seccomp_action_logged_from_name(&action_logged, name))
|
| 1203 | return false;
|
| 1204 |
|
| 1205 | *actions_logged |= action_logged;
|
| 1206 | }
|
| 1207 |
|
| 1208 | return true;
|
| 1209 | }
|
| 1210 |
|
| 1211 | static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
|
| 1212 | void __user *buffer, size_t *lenp,
|
| 1213 | loff_t *ppos)
|
| 1214 | {
|
| 1215 | char names[sizeof(seccomp_actions_avail)];
|
| 1216 | struct ctl_table table;
|
| 1217 | int ret;
|
| 1218 |
|
| 1219 | if (write && !capable(CAP_SYS_ADMIN))
|
| 1220 | return -EPERM;
|
| 1221 |
|
| 1222 | memset(names, 0, sizeof(names));
|
| 1223 |
|
| 1224 | if (!write) {
|
| 1225 | if (!seccomp_names_from_actions_logged(names, sizeof(names),
|
| 1226 | seccomp_actions_logged))
|
| 1227 | return -EINVAL;
|
| 1228 | }
|
| 1229 |
|
| 1230 | table = *ro_table;
|
| 1231 | table.data = names;
|
| 1232 | table.maxlen = sizeof(names);
|
| 1233 | ret = proc_dostring(&table, write, buffer, lenp, ppos);
|
| 1234 | if (ret)
|
| 1235 | return ret;
|
| 1236 |
|
| 1237 | if (write) {
|
| 1238 | u32 actions_logged;
|
| 1239 |
|
| 1240 | if (!seccomp_actions_logged_from_names(&actions_logged,
|
| 1241 | table.data))
|
| 1242 | return -EINVAL;
|
| 1243 |
|
| 1244 | if (actions_logged & SECCOMP_LOG_ALLOW)
|
| 1245 | return -EINVAL;
|
| 1246 |
|
| 1247 | seccomp_actions_logged = actions_logged;
|
| 1248 | }
|
| 1249 |
|
| 1250 | return 0;
|
| 1251 | }
|
| 1252 |
|
| 1253 | static struct ctl_path seccomp_sysctl_path[] = {
|
| 1254 | { .procname = "kernel", },
|
| 1255 | { .procname = "seccomp", },
|
| 1256 | { }
|
| 1257 | };
|
| 1258 |
|
| 1259 | static struct ctl_table seccomp_sysctl_table[] = {
|
| 1260 | {
|
| 1261 | .procname = "actions_avail",
|
| 1262 | .data = (void *) &seccomp_actions_avail,
|
| 1263 | .maxlen = sizeof(seccomp_actions_avail),
|
| 1264 | .mode = 0444,
|
| 1265 | .proc_handler = proc_dostring,
|
| 1266 | },
|
| 1267 | {
|
| 1268 | .procname = "actions_logged",
|
| 1269 | .mode = 0644,
|
| 1270 | .proc_handler = seccomp_actions_logged_handler,
|
| 1271 | },
|
| 1272 | { }
|
| 1273 | };
|
| 1274 |
|
| 1275 | static int __init seccomp_sysctl_init(void)
|
| 1276 | {
|
| 1277 | struct ctl_table_header *hdr;
|
| 1278 |
|
| 1279 | hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
|
| 1280 | if (!hdr)
|
| 1281 | pr_warn("seccomp: sysctl registration failed\n");
|
| 1282 | else
|
| 1283 | kmemleak_not_leak(hdr);
|
| 1284 |
|
| 1285 | return 0;
|
| 1286 | }
|
| 1287 |
|
| 1288 | device_initcall(seccomp_sysctl_init)
|
| 1289 |
|
| 1290 | #endif
|