Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
10c28d93 AK |
2 | #include <linux/slab.h> |
3 | #include <linux/file.h> | |
4 | #include <linux/fdtable.h> | |
70d78fe7 | 5 | #include <linux/freezer.h> |
10c28d93 AK |
6 | #include <linux/mm.h> |
7 | #include <linux/stat.h> | |
8 | #include <linux/fcntl.h> | |
9 | #include <linux/swap.h> | |
315c6926 | 10 | #include <linux/ctype.h> |
10c28d93 AK |
11 | #include <linux/string.h> |
12 | #include <linux/init.h> | |
13 | #include <linux/pagemap.h> | |
14 | #include <linux/perf_event.h> | |
15 | #include <linux/highmem.h> | |
16 | #include <linux/spinlock.h> | |
17 | #include <linux/key.h> | |
18 | #include <linux/personality.h> | |
19 | #include <linux/binfmts.h> | |
179899fd | 20 | #include <linux/coredump.h> |
f7ccbae4 | 21 | #include <linux/sched/coredump.h> |
3f07c014 | 22 | #include <linux/sched/signal.h> |
68db0cf1 | 23 | #include <linux/sched/task_stack.h> |
10c28d93 AK |
24 | #include <linux/utsname.h> |
25 | #include <linux/pid_namespace.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/namei.h> | |
28 | #include <linux/mount.h> | |
29 | #include <linux/security.h> | |
30 | #include <linux/syscalls.h> | |
31 | #include <linux/tsacct_kern.h> | |
32 | #include <linux/cn_proc.h> | |
33 | #include <linux/audit.h> | |
34 | #include <linux/tracehook.h> | |
35 | #include <linux/kmod.h> | |
36 | #include <linux/fsnotify.h> | |
37 | #include <linux/fs_struct.h> | |
38 | #include <linux/pipe_fs_i.h> | |
39 | #include <linux/oom.h> | |
40 | #include <linux/compat.h> | |
378c6520 JH |
41 | #include <linux/fs.h> |
42 | #include <linux/path.h> | |
03927c8a | 43 | #include <linux/timekeeping.h> |
10c28d93 | 44 | |
7c0f6ba6 | 45 | #include <linux/uaccess.h> |
10c28d93 AK |
46 | #include <asm/mmu_context.h> |
47 | #include <asm/tlb.h> | |
48 | #include <asm/exec.h> | |
49 | ||
50 | #include <trace/events/task.h> | |
51 | #include "internal.h" | |
52 | ||
53 | #include <trace/events/sched.h> | |
54 | ||
55 | int core_uses_pid; | |
10c28d93 | 56 | unsigned int core_pipe_limit; |
3ceadcf6 ON |
57 | char core_pattern[CORENAME_MAX_SIZE] = "core"; |
58 | static int core_name_size = CORENAME_MAX_SIZE; | |
10c28d93 AK |
59 | |
60 | struct core_name { | |
61 | char *corename; | |
62 | int used, size; | |
63 | }; | |
10c28d93 AK |
64 | |
65 | /* The maximal length of core_pattern is also specified in sysctl.c */ | |
66 | ||
3ceadcf6 | 67 | static int expand_corename(struct core_name *cn, int size) |
10c28d93 | 68 | { |
e7fd1549 | 69 | char *corename = krealloc(cn->corename, size, GFP_KERNEL); |
10c28d93 | 70 | |
e7fd1549 | 71 | if (!corename) |
10c28d93 | 72 | return -ENOMEM; |
10c28d93 | 73 | |
3ceadcf6 ON |
74 | if (size > core_name_size) /* racy but harmless */ |
75 | core_name_size = size; | |
76 | ||
77 | cn->size = ksize(corename); | |
e7fd1549 | 78 | cn->corename = corename; |
10c28d93 AK |
79 | return 0; |
80 | } | |
81 | ||
b4176b7c NI |
82 | static __printf(2, 0) int cn_vprintf(struct core_name *cn, const char *fmt, |
83 | va_list arg) | |
10c28d93 | 84 | { |
5fe9d8ca | 85 | int free, need; |
404ca80e | 86 | va_list arg_copy; |
10c28d93 | 87 | |
5fe9d8ca ON |
88 | again: |
89 | free = cn->size - cn->used; | |
404ca80e ED |
90 | |
91 | va_copy(arg_copy, arg); | |
92 | need = vsnprintf(cn->corename + cn->used, free, fmt, arg_copy); | |
93 | va_end(arg_copy); | |
94 | ||
5fe9d8ca ON |
95 | if (need < free) { |
96 | cn->used += need; | |
97 | return 0; | |
98 | } | |
10c28d93 | 99 | |
3ceadcf6 | 100 | if (!expand_corename(cn, cn->size + need - free + 1)) |
5fe9d8ca | 101 | goto again; |
10c28d93 | 102 | |
5fe9d8ca | 103 | return -ENOMEM; |
10c28d93 AK |
104 | } |
105 | ||
b4176b7c | 106 | static __printf(2, 3) int cn_printf(struct core_name *cn, const char *fmt, ...) |
bc03c691 ON |
107 | { |
108 | va_list arg; | |
109 | int ret; | |
110 | ||
111 | va_start(arg, fmt); | |
112 | ret = cn_vprintf(cn, fmt, arg); | |
113 | va_end(arg); | |
114 | ||
115 | return ret; | |
116 | } | |
117 | ||
b4176b7c NI |
118 | static __printf(2, 3) |
119 | int cn_esc_printf(struct core_name *cn, const char *fmt, ...) | |
10c28d93 | 120 | { |
923bed03 ON |
121 | int cur = cn->used; |
122 | va_list arg; | |
123 | int ret; | |
124 | ||
125 | va_start(arg, fmt); | |
126 | ret = cn_vprintf(cn, fmt, arg); | |
127 | va_end(arg); | |
128 | ||
ac94b6e3 JH |
129 | if (ret == 0) { |
130 | /* | |
131 | * Ensure that this coredump name component can't cause the | |
132 | * resulting corefile path to consist of a ".." or ".". | |
133 | */ | |
134 | if ((cn->used - cur == 1 && cn->corename[cur] == '.') || | |
135 | (cn->used - cur == 2 && cn->corename[cur] == '.' | |
136 | && cn->corename[cur+1] == '.')) | |
137 | cn->corename[cur] = '!'; | |
138 | ||
139 | /* | |
140 | * Empty names are fishy and could be used to create a "//" in a | |
141 | * corefile name, causing the coredump to happen one directory | |
142 | * level too high. Enforce that all components of the core | |
143 | * pattern are at least one character long. | |
144 | */ | |
145 | if (cn->used == cur) | |
146 | ret = cn_printf(cn, "!"); | |
147 | } | |
148 | ||
923bed03 ON |
149 | for (; cur < cn->used; ++cur) { |
150 | if (cn->corename[cur] == '/') | |
151 | cn->corename[cur] = '!'; | |
152 | } | |
153 | return ret; | |
10c28d93 AK |
154 | } |
155 | ||
156 | static int cn_print_exe_file(struct core_name *cn) | |
157 | { | |
158 | struct file *exe_file; | |
159 | char *pathbuf, *path; | |
160 | int ret; | |
161 | ||
162 | exe_file = get_mm_exe_file(current->mm); | |
923bed03 ON |
163 | if (!exe_file) |
164 | return cn_esc_printf(cn, "%s (path unknown)", current->comm); | |
10c28d93 | 165 | |
0ee931c4 | 166 | pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); |
10c28d93 AK |
167 | if (!pathbuf) { |
168 | ret = -ENOMEM; | |
169 | goto put_exe_file; | |
170 | } | |
171 | ||
9bf39ab2 | 172 | path = file_path(exe_file, pathbuf, PATH_MAX); |
10c28d93 AK |
173 | if (IS_ERR(path)) { |
174 | ret = PTR_ERR(path); | |
175 | goto free_buf; | |
176 | } | |
177 | ||
923bed03 | 178 | ret = cn_esc_printf(cn, "%s", path); |
10c28d93 AK |
179 | |
180 | free_buf: | |
181 | kfree(pathbuf); | |
182 | put_exe_file: | |
183 | fput(exe_file); | |
184 | return ret; | |
185 | } | |
186 | ||
187 | /* format_corename will inspect the pattern parameter, and output a | |
188 | * name into corename, which must have space for at least | |
189 | * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. | |
190 | */ | |
315c6926 PW |
191 | static int format_corename(struct core_name *cn, struct coredump_params *cprm, |
192 | size_t **argv, int *argc) | |
10c28d93 AK |
193 | { |
194 | const struct cred *cred = current_cred(); | |
195 | const char *pat_ptr = core_pattern; | |
196 | int ispipe = (*pat_ptr == '|'); | |
315c6926 | 197 | bool was_space = false; |
10c28d93 AK |
198 | int pid_in_pattern = 0; |
199 | int err = 0; | |
200 | ||
e7fd1549 | 201 | cn->used = 0; |
3ceadcf6 ON |
202 | cn->corename = NULL; |
203 | if (expand_corename(cn, core_name_size)) | |
10c28d93 | 204 | return -ENOMEM; |
888ffc59 ON |
205 | cn->corename[0] = '\0'; |
206 | ||
315c6926 PW |
207 | if (ispipe) { |
208 | int argvs = sizeof(core_pattern) / 2; | |
209 | (*argv) = kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL); | |
210 | if (!(*argv)) | |
211 | return -ENOMEM; | |
212 | (*argv)[(*argc)++] = 0; | |
888ffc59 | 213 | ++pat_ptr; |
315c6926 | 214 | } |
10c28d93 AK |
215 | |
216 | /* Repeat as long as we have more pattern to process and more output | |
217 | space */ | |
218 | while (*pat_ptr) { | |
315c6926 PW |
219 | /* |
220 | * Split on spaces before doing template expansion so that | |
221 | * %e and %E don't get split if they have spaces in them | |
222 | */ | |
223 | if (ispipe) { | |
224 | if (isspace(*pat_ptr)) { | |
225 | was_space = true; | |
226 | pat_ptr++; | |
227 | continue; | |
228 | } else if (was_space) { | |
229 | was_space = false; | |
230 | err = cn_printf(cn, "%c", '\0'); | |
231 | if (err) | |
232 | return err; | |
233 | (*argv)[(*argc)++] = cn->used; | |
234 | } | |
235 | } | |
10c28d93 | 236 | if (*pat_ptr != '%') { |
10c28d93 AK |
237 | err = cn_printf(cn, "%c", *pat_ptr++); |
238 | } else { | |
239 | switch (*++pat_ptr) { | |
240 | /* single % at the end, drop that */ | |
241 | case 0: | |
242 | goto out; | |
243 | /* Double percent, output one percent */ | |
244 | case '%': | |
245 | err = cn_printf(cn, "%c", '%'); | |
246 | break; | |
247 | /* pid */ | |
248 | case 'p': | |
249 | pid_in_pattern = 1; | |
250 | err = cn_printf(cn, "%d", | |
251 | task_tgid_vnr(current)); | |
252 | break; | |
65aafb1e SG |
253 | /* global pid */ |
254 | case 'P': | |
255 | err = cn_printf(cn, "%d", | |
256 | task_tgid_nr(current)); | |
257 | break; | |
b03023ec ON |
258 | case 'i': |
259 | err = cn_printf(cn, "%d", | |
260 | task_pid_vnr(current)); | |
261 | break; | |
262 | case 'I': | |
263 | err = cn_printf(cn, "%d", | |
264 | task_pid_nr(current)); | |
265 | break; | |
10c28d93 AK |
266 | /* uid */ |
267 | case 'u': | |
5202efe5 NI |
268 | err = cn_printf(cn, "%u", |
269 | from_kuid(&init_user_ns, | |
270 | cred->uid)); | |
10c28d93 AK |
271 | break; |
272 | /* gid */ | |
273 | case 'g': | |
5202efe5 NI |
274 | err = cn_printf(cn, "%u", |
275 | from_kgid(&init_user_ns, | |
276 | cred->gid)); | |
10c28d93 | 277 | break; |
12a2b4b2 ON |
278 | case 'd': |
279 | err = cn_printf(cn, "%d", | |
280 | __get_dumpable(cprm->mm_flags)); | |
281 | break; | |
10c28d93 AK |
282 | /* signal that caused the coredump */ |
283 | case 's': | |
b4176b7c NI |
284 | err = cn_printf(cn, "%d", |
285 | cprm->siginfo->si_signo); | |
10c28d93 AK |
286 | break; |
287 | /* UNIX time of coredump */ | |
288 | case 't': { | |
03927c8a AB |
289 | time64_t time; |
290 | ||
291 | time = ktime_get_real_seconds(); | |
292 | err = cn_printf(cn, "%lld", time); | |
10c28d93 AK |
293 | break; |
294 | } | |
295 | /* hostname */ | |
923bed03 | 296 | case 'h': |
10c28d93 | 297 | down_read(&uts_sem); |
923bed03 | 298 | err = cn_esc_printf(cn, "%s", |
10c28d93 AK |
299 | utsname()->nodename); |
300 | up_read(&uts_sem); | |
10c28d93 | 301 | break; |
10c28d93 | 302 | /* executable */ |
923bed03 ON |
303 | case 'e': |
304 | err = cn_esc_printf(cn, "%s", current->comm); | |
10c28d93 | 305 | break; |
10c28d93 AK |
306 | case 'E': |
307 | err = cn_print_exe_file(cn); | |
308 | break; | |
309 | /* core limit size */ | |
310 | case 'c': | |
311 | err = cn_printf(cn, "%lu", | |
312 | rlimit(RLIMIT_CORE)); | |
313 | break; | |
314 | default: | |
315 | break; | |
316 | } | |
317 | ++pat_ptr; | |
318 | } | |
319 | ||
320 | if (err) | |
321 | return err; | |
322 | } | |
323 | ||
888ffc59 | 324 | out: |
10c28d93 AK |
325 | /* Backward compatibility with core_uses_pid: |
326 | * | |
327 | * If core_pattern does not include a %p (as is the default) | |
328 | * and core_uses_pid is set, then .%pid will be appended to | |
329 | * the filename. Do not do this for piped commands. */ | |
330 | if (!ispipe && !pid_in_pattern && core_uses_pid) { | |
331 | err = cn_printf(cn, ".%d", task_tgid_vnr(current)); | |
332 | if (err) | |
333 | return err; | |
334 | } | |
10c28d93 AK |
335 | return ispipe; |
336 | } | |
337 | ||
5fa534c9 | 338 | static int zap_process(struct task_struct *start, int exit_code, int flags) |
10c28d93 AK |
339 | { |
340 | struct task_struct *t; | |
341 | int nr = 0; | |
342 | ||
5fa534c9 ON |
343 | /* ignore all signals except SIGKILL, see prepare_signal() */ |
344 | start->signal->flags = SIGNAL_GROUP_COREDUMP | flags; | |
10c28d93 AK |
345 | start->signal->group_exit_code = exit_code; |
346 | start->signal->group_stop_count = 0; | |
347 | ||
d61ba589 | 348 | for_each_thread(start, t) { |
10c28d93 AK |
349 | task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); |
350 | if (t != current && t->mm) { | |
351 | sigaddset(&t->pending.signal, SIGKILL); | |
352 | signal_wake_up(t, 1); | |
353 | nr++; | |
354 | } | |
d61ba589 | 355 | } |
10c28d93 AK |
356 | |
357 | return nr; | |
358 | } | |
359 | ||
403bad72 ON |
360 | static int zap_threads(struct task_struct *tsk, struct mm_struct *mm, |
361 | struct core_state *core_state, int exit_code) | |
10c28d93 AK |
362 | { |
363 | struct task_struct *g, *p; | |
364 | unsigned long flags; | |
365 | int nr = -EAGAIN; | |
366 | ||
367 | spin_lock_irq(&tsk->sighand->siglock); | |
368 | if (!signal_group_exit(tsk->signal)) { | |
369 | mm->core_state = core_state; | |
6cd8f0ac | 370 | tsk->signal->group_exit_task = tsk; |
5fa534c9 | 371 | nr = zap_process(tsk, exit_code, 0); |
403bad72 | 372 | clear_tsk_thread_flag(tsk, TIF_SIGPENDING); |
10c28d93 AK |
373 | } |
374 | spin_unlock_irq(&tsk->sighand->siglock); | |
375 | if (unlikely(nr < 0)) | |
376 | return nr; | |
377 | ||
aed8adb7 | 378 | tsk->flags |= PF_DUMPCORE; |
10c28d93 AK |
379 | if (atomic_read(&mm->mm_users) == nr + 1) |
380 | goto done; | |
381 | /* | |
382 | * We should find and kill all tasks which use this mm, and we should | |
383 | * count them correctly into ->nr_threads. We don't take tasklist | |
384 | * lock, but this is safe wrt: | |
385 | * | |
386 | * fork: | |
387 | * None of sub-threads can fork after zap_process(leader). All | |
388 | * processes which were created before this point should be | |
389 | * visible to zap_threads() because copy_process() adds the new | |
390 | * process to the tail of init_task.tasks list, and lock/unlock | |
391 | * of ->siglock provides a memory barrier. | |
392 | * | |
393 | * do_exit: | |
394 | * The caller holds mm->mmap_sem. This means that the task which | |
395 | * uses this mm can't pass exit_mm(), so it can't exit or clear | |
396 | * its ->mm. | |
397 | * | |
398 | * de_thread: | |
399 | * It does list_replace_rcu(&leader->tasks, ¤t->tasks), | |
400 | * we must see either old or new leader, this does not matter. | |
401 | * However, it can change p->sighand, so lock_task_sighand(p) | |
402 | * must be used. Since p->mm != NULL and we hold ->mmap_sem | |
403 | * it can't fail. | |
404 | * | |
405 | * Note also that "g" can be the old leader with ->mm == NULL | |
406 | * and already unhashed and thus removed from ->thread_group. | |
407 | * This is OK, __unhash_process()->list_del_rcu() does not | |
408 | * clear the ->next pointer, we will find the new leader via | |
409 | * next_thread(). | |
410 | */ | |
411 | rcu_read_lock(); | |
412 | for_each_process(g) { | |
413 | if (g == tsk->group_leader) | |
414 | continue; | |
415 | if (g->flags & PF_KTHREAD) | |
416 | continue; | |
d61ba589 ON |
417 | |
418 | for_each_thread(g, p) { | |
419 | if (unlikely(!p->mm)) | |
420 | continue; | |
421 | if (unlikely(p->mm == mm)) { | |
422 | lock_task_sighand(p, &flags); | |
423 | nr += zap_process(p, exit_code, | |
424 | SIGNAL_GROUP_EXIT); | |
425 | unlock_task_sighand(p, &flags); | |
10c28d93 | 426 | } |
d61ba589 ON |
427 | break; |
428 | } | |
10c28d93 AK |
429 | } |
430 | rcu_read_unlock(); | |
431 | done: | |
432 | atomic_set(&core_state->nr_threads, nr); | |
433 | return nr; | |
434 | } | |
435 | ||
436 | static int coredump_wait(int exit_code, struct core_state *core_state) | |
437 | { | |
438 | struct task_struct *tsk = current; | |
439 | struct mm_struct *mm = tsk->mm; | |
440 | int core_waiters = -EBUSY; | |
441 | ||
442 | init_completion(&core_state->startup); | |
443 | core_state->dumper.task = tsk; | |
444 | core_state->dumper.next = NULL; | |
445 | ||
4136c26b MH |
446 | if (down_write_killable(&mm->mmap_sem)) |
447 | return -EINTR; | |
448 | ||
10c28d93 AK |
449 | if (!mm->core_state) |
450 | core_waiters = zap_threads(tsk, mm, core_state, exit_code); | |
451 | up_write(&mm->mmap_sem); | |
452 | ||
453 | if (core_waiters > 0) { | |
454 | struct core_thread *ptr; | |
455 | ||
70d78fe7 | 456 | freezer_do_not_count(); |
10c28d93 | 457 | wait_for_completion(&core_state->startup); |
70d78fe7 | 458 | freezer_count(); |
10c28d93 AK |
459 | /* |
460 | * Wait for all the threads to become inactive, so that | |
461 | * all the thread context (extended register state, like | |
462 | * fpu etc) gets copied to the memory. | |
463 | */ | |
464 | ptr = core_state->dumper.next; | |
465 | while (ptr != NULL) { | |
466 | wait_task_inactive(ptr->task, 0); | |
467 | ptr = ptr->next; | |
468 | } | |
469 | } | |
470 | ||
471 | return core_waiters; | |
472 | } | |
473 | ||
acdedd99 | 474 | static void coredump_finish(struct mm_struct *mm, bool core_dumped) |
10c28d93 AK |
475 | { |
476 | struct core_thread *curr, *next; | |
477 | struct task_struct *task; | |
478 | ||
6cd8f0ac | 479 | spin_lock_irq(¤t->sighand->siglock); |
acdedd99 ON |
480 | if (core_dumped && !__fatal_signal_pending(current)) |
481 | current->signal->group_exit_code |= 0x80; | |
6cd8f0ac ON |
482 | current->signal->group_exit_task = NULL; |
483 | current->signal->flags = SIGNAL_GROUP_EXIT; | |
484 | spin_unlock_irq(¤t->sighand->siglock); | |
485 | ||
10c28d93 AK |
486 | next = mm->core_state->dumper.next; |
487 | while ((curr = next) != NULL) { | |
488 | next = curr->next; | |
489 | task = curr->task; | |
490 | /* | |
491 | * see exit_mm(), curr->task must not see | |
492 | * ->task == NULL before we read ->next. | |
493 | */ | |
494 | smp_mb(); | |
495 | curr->task = NULL; | |
496 | wake_up_process(task); | |
497 | } | |
498 | ||
499 | mm->core_state = NULL; | |
500 | } | |
501 | ||
528f827e ON |
502 | static bool dump_interrupted(void) |
503 | { | |
504 | /* | |
505 | * SIGKILL or freezing() interrupt the coredumping. Perhaps we | |
506 | * can do try_to_freeze() and check __fatal_signal_pending(), | |
507 | * but then we need to teach dump_write() to restart and clear | |
508 | * TIF_SIGPENDING. | |
509 | */ | |
510 | return signal_pending(current); | |
511 | } | |
512 | ||
10c28d93 AK |
513 | static void wait_for_dump_helpers(struct file *file) |
514 | { | |
de32ec4c | 515 | struct pipe_inode_info *pipe = file->private_data; |
10c28d93 AK |
516 | |
517 | pipe_lock(pipe); | |
518 | pipe->readers++; | |
519 | pipe->writers--; | |
dc7ee2aa ON |
520 | wake_up_interruptible_sync(&pipe->wait); |
521 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
522 | pipe_unlock(pipe); | |
10c28d93 | 523 | |
dc7ee2aa ON |
524 | /* |
525 | * We actually want wait_event_freezable() but then we need | |
526 | * to clear TIF_SIGPENDING and improve dump_interrupted(). | |
527 | */ | |
528 | wait_event_interruptible(pipe->wait, pipe->readers == 1); | |
10c28d93 | 529 | |
dc7ee2aa | 530 | pipe_lock(pipe); |
10c28d93 AK |
531 | pipe->readers--; |
532 | pipe->writers++; | |
533 | pipe_unlock(pipe); | |
10c28d93 AK |
534 | } |
535 | ||
536 | /* | |
537 | * umh_pipe_setup | |
538 | * helper function to customize the process used | |
539 | * to collect the core in userspace. Specifically | |
540 | * it sets up a pipe and installs it as fd 0 (stdin) | |
541 | * for the process. Returns 0 on success, or | |
542 | * PTR_ERR on failure. | |
543 | * Note that it also sets the core limit to 1. This | |
544 | * is a special value that we use to trap recursive | |
545 | * core dumps | |
546 | */ | |
547 | static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) | |
548 | { | |
549 | struct file *files[2]; | |
550 | struct coredump_params *cp = (struct coredump_params *)info->data; | |
551 | int err = create_pipe_files(files, 0); | |
552 | if (err) | |
553 | return err; | |
554 | ||
555 | cp->file = files[1]; | |
556 | ||
45525b26 AV |
557 | err = replace_fd(0, files[0], 0); |
558 | fput(files[0]); | |
10c28d93 AK |
559 | /* and disallow core files too */ |
560 | current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; | |
561 | ||
45525b26 | 562 | return err; |
10c28d93 AK |
563 | } |
564 | ||
ae7795bc | 565 | void do_coredump(const kernel_siginfo_t *siginfo) |
10c28d93 AK |
566 | { |
567 | struct core_state core_state; | |
568 | struct core_name cn; | |
569 | struct mm_struct *mm = current->mm; | |
570 | struct linux_binfmt * binfmt; | |
571 | const struct cred *old_cred; | |
572 | struct cred *cred; | |
573 | int retval = 0; | |
10c28d93 | 574 | int ispipe; |
315c6926 PW |
575 | size_t *argv = NULL; |
576 | int argc = 0; | |
10c28d93 | 577 | struct files_struct *displaced; |
fbb18169 JH |
578 | /* require nonrelative corefile path and be extra careful */ |
579 | bool need_suid_safe = false; | |
acdedd99 | 580 | bool core_dumped = false; |
10c28d93 AK |
581 | static atomic_t core_dump_count = ATOMIC_INIT(0); |
582 | struct coredump_params cprm = { | |
5ab1c309 | 583 | .siginfo = siginfo, |
541880d9 | 584 | .regs = signal_pt_regs(), |
10c28d93 AK |
585 | .limit = rlimit(RLIMIT_CORE), |
586 | /* | |
587 | * We must use the same mm->flags while dumping core to avoid | |
588 | * inconsistency of bit flags, since this flag is not protected | |
589 | * by any locks. | |
590 | */ | |
591 | .mm_flags = mm->flags, | |
592 | }; | |
593 | ||
5ab1c309 | 594 | audit_core_dumps(siginfo->si_signo); |
10c28d93 AK |
595 | |
596 | binfmt = mm->binfmt; | |
597 | if (!binfmt || !binfmt->core_dump) | |
598 | goto fail; | |
599 | if (!__get_dumpable(cprm.mm_flags)) | |
600 | goto fail; | |
601 | ||
602 | cred = prepare_creds(); | |
603 | if (!cred) | |
604 | goto fail; | |
605 | /* | |
606 | * We cannot trust fsuid as being the "true" uid of the process | |
607 | * nor do we know its entire history. We only know it was tainted | |
608 | * so we dump it as root in mode 2, and only into a controlled | |
609 | * environment (pipe handler or fully qualified path). | |
610 | */ | |
e579d2c2 | 611 | if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) { |
10c28d93 | 612 | /* Setuid core dump mode */ |
10c28d93 | 613 | cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */ |
fbb18169 | 614 | need_suid_safe = true; |
10c28d93 AK |
615 | } |
616 | ||
5ab1c309 | 617 | retval = coredump_wait(siginfo->si_signo, &core_state); |
10c28d93 AK |
618 | if (retval < 0) |
619 | goto fail_creds; | |
620 | ||
621 | old_cred = override_creds(cred); | |
622 | ||
315c6926 | 623 | ispipe = format_corename(&cn, &cprm, &argv, &argc); |
10c28d93 | 624 | |
fb96c475 | 625 | if (ispipe) { |
315c6926 | 626 | int argi; |
10c28d93 AK |
627 | int dump_count; |
628 | char **helper_argv; | |
907ed132 | 629 | struct subprocess_info *sub_info; |
10c28d93 AK |
630 | |
631 | if (ispipe < 0) { | |
632 | printk(KERN_WARNING "format_corename failed\n"); | |
633 | printk(KERN_WARNING "Aborting core\n"); | |
e7fd1549 | 634 | goto fail_unlock; |
10c28d93 AK |
635 | } |
636 | ||
637 | if (cprm.limit == 1) { | |
638 | /* See umh_pipe_setup() which sets RLIMIT_CORE = 1. | |
639 | * | |
640 | * Normally core limits are irrelevant to pipes, since | |
641 | * we're not writing to the file system, but we use | |
fcbc32bc | 642 | * cprm.limit of 1 here as a special value, this is a |
10c28d93 AK |
643 | * consistent way to catch recursive crashes. |
644 | * We can still crash if the core_pattern binary sets | |
645 | * RLIM_CORE = !1, but it runs as root, and can do | |
646 | * lots of stupid things. | |
647 | * | |
648 | * Note that we use task_tgid_vnr here to grab the pid | |
649 | * of the process group leader. That way we get the | |
650 | * right pid if a thread in a multi-threaded | |
651 | * core_pattern process dies. | |
652 | */ | |
653 | printk(KERN_WARNING | |
654 | "Process %d(%s) has RLIMIT_CORE set to 1\n", | |
655 | task_tgid_vnr(current), current->comm); | |
656 | printk(KERN_WARNING "Aborting core\n"); | |
657 | goto fail_unlock; | |
658 | } | |
659 | cprm.limit = RLIM_INFINITY; | |
660 | ||
661 | dump_count = atomic_inc_return(&core_dump_count); | |
662 | if (core_pipe_limit && (core_pipe_limit < dump_count)) { | |
663 | printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", | |
664 | task_tgid_vnr(current), current->comm); | |
665 | printk(KERN_WARNING "Skipping core dump\n"); | |
666 | goto fail_dropcount; | |
667 | } | |
668 | ||
315c6926 PW |
669 | helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv), |
670 | GFP_KERNEL); | |
10c28d93 AK |
671 | if (!helper_argv) { |
672 | printk(KERN_WARNING "%s failed to allocate memory\n", | |
673 | __func__); | |
674 | goto fail_dropcount; | |
675 | } | |
315c6926 PW |
676 | for (argi = 0; argi < argc; argi++) |
677 | helper_argv[argi] = cn.corename + argv[argi]; | |
678 | helper_argv[argi] = NULL; | |
10c28d93 | 679 | |
907ed132 LDM |
680 | retval = -ENOMEM; |
681 | sub_info = call_usermodehelper_setup(helper_argv[0], | |
682 | helper_argv, NULL, GFP_KERNEL, | |
683 | umh_pipe_setup, NULL, &cprm); | |
684 | if (sub_info) | |
685 | retval = call_usermodehelper_exec(sub_info, | |
686 | UMH_WAIT_EXEC); | |
687 | ||
315c6926 | 688 | kfree(helper_argv); |
10c28d93 | 689 | if (retval) { |
888ffc59 | 690 | printk(KERN_INFO "Core dump to |%s pipe failed\n", |
10c28d93 AK |
691 | cn.corename); |
692 | goto close_fail; | |
fb96c475 | 693 | } |
10c28d93 AK |
694 | } else { |
695 | struct inode *inode; | |
378c6520 JH |
696 | int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW | |
697 | O_LARGEFILE | O_EXCL; | |
10c28d93 AK |
698 | |
699 | if (cprm.limit < binfmt->min_coredump) | |
700 | goto fail_unlock; | |
701 | ||
fbb18169 | 702 | if (need_suid_safe && cn.corename[0] != '/') { |
10c28d93 AK |
703 | printk(KERN_WARNING "Pid %d(%s) can only dump core "\ |
704 | "to fully qualified path!\n", | |
705 | task_tgid_vnr(current), current->comm); | |
706 | printk(KERN_WARNING "Skipping core dump\n"); | |
707 | goto fail_unlock; | |
708 | } | |
709 | ||
fbb18169 JH |
710 | /* |
711 | * Unlink the file if it exists unless this is a SUID | |
712 | * binary - in that case, we're running around with root | |
713 | * privs and don't want to unlink another user's coredump. | |
714 | */ | |
715 | if (!need_suid_safe) { | |
fbb18169 JH |
716 | /* |
717 | * If it doesn't exist, that's fine. If there's some | |
718 | * other problem, we'll catch it at the filp_open(). | |
719 | */ | |
96271654 | 720 | do_unlinkat(AT_FDCWD, getname_kernel(cn.corename)); |
fbb18169 JH |
721 | } |
722 | ||
723 | /* | |
724 | * There is a race between unlinking and creating the | |
725 | * file, but if that causes an EEXIST here, that's | |
726 | * fine - another process raced with us while creating | |
727 | * the corefile, and the other process won. To userspace, | |
728 | * what matters is that at least one of the two processes | |
729 | * writes its coredump successfully, not which one. | |
730 | */ | |
378c6520 JH |
731 | if (need_suid_safe) { |
732 | /* | |
733 | * Using user namespaces, normal user tasks can change | |
734 | * their current->fs->root to point to arbitrary | |
735 | * directories. Since the intention of the "only dump | |
736 | * with a fully qualified path" rule is to control where | |
737 | * coredumps may be placed using root privileges, | |
738 | * current->fs->root must not be used. Instead, use the | |
739 | * root directory of init_task. | |
740 | */ | |
741 | struct path root; | |
742 | ||
743 | task_lock(&init_task); | |
744 | get_fs_root(init_task.fs, &root); | |
745 | task_unlock(&init_task); | |
746 | cprm.file = file_open_root(root.dentry, root.mnt, | |
747 | cn.corename, open_flags, 0600); | |
748 | path_put(&root); | |
749 | } else { | |
750 | cprm.file = filp_open(cn.corename, open_flags, 0600); | |
751 | } | |
10c28d93 AK |
752 | if (IS_ERR(cprm.file)) |
753 | goto fail_unlock; | |
754 | ||
496ad9aa | 755 | inode = file_inode(cprm.file); |
10c28d93 AK |
756 | if (inode->i_nlink > 1) |
757 | goto close_fail; | |
758 | if (d_unhashed(cprm.file->f_path.dentry)) | |
759 | goto close_fail; | |
760 | /* | |
761 | * AK: actually i see no reason to not allow this for named | |
762 | * pipes etc, but keep the previous behaviour for now. | |
763 | */ | |
764 | if (!S_ISREG(inode->i_mode)) | |
765 | goto close_fail; | |
766 | /* | |
40f705a7 JH |
767 | * Don't dump core if the filesystem changed owner or mode |
768 | * of the file during file creation. This is an issue when | |
769 | * a process dumps core while its cwd is e.g. on a vfat | |
770 | * filesystem. | |
10c28d93 AK |
771 | */ |
772 | if (!uid_eq(inode->i_uid, current_fsuid())) | |
773 | goto close_fail; | |
40f705a7 JH |
774 | if ((inode->i_mode & 0677) != 0600) |
775 | goto close_fail; | |
86cc0584 | 776 | if (!(cprm.file->f_mode & FMODE_CAN_WRITE)) |
10c28d93 AK |
777 | goto close_fail; |
778 | if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) | |
779 | goto close_fail; | |
780 | } | |
781 | ||
782 | /* get us an unshared descriptor table; almost always a no-op */ | |
783 | retval = unshare_files(&displaced); | |
784 | if (retval) | |
785 | goto close_fail; | |
786 | if (displaced) | |
787 | put_files_struct(displaced); | |
e86d35c3 AV |
788 | if (!dump_interrupted()) { |
789 | file_start_write(cprm.file); | |
790 | core_dumped = binfmt->core_dump(&cprm); | |
791 | file_end_write(cprm.file); | |
792 | } | |
10c28d93 AK |
793 | if (ispipe && core_pipe_limit) |
794 | wait_for_dump_helpers(cprm.file); | |
795 | close_fail: | |
796 | if (cprm.file) | |
797 | filp_close(cprm.file, NULL); | |
798 | fail_dropcount: | |
799 | if (ispipe) | |
800 | atomic_dec(&core_dump_count); | |
801 | fail_unlock: | |
315c6926 | 802 | kfree(argv); |
10c28d93 | 803 | kfree(cn.corename); |
acdedd99 | 804 | coredump_finish(mm, core_dumped); |
10c28d93 AK |
805 | revert_creds(old_cred); |
806 | fail_creds: | |
807 | put_cred(cred); | |
808 | fail: | |
809 | return; | |
810 | } | |
811 | ||
812 | /* | |
813 | * Core dumping helper functions. These are the only things you should | |
814 | * do on a core-file: use only these functions to write out all the | |
815 | * necessary info. | |
816 | */ | |
ecc8c772 AV |
817 | int dump_emit(struct coredump_params *cprm, const void *addr, int nr) |
818 | { | |
819 | struct file *file = cprm->file; | |
2507a4fb AV |
820 | loff_t pos = file->f_pos; |
821 | ssize_t n; | |
2c4cb043 | 822 | if (cprm->written + nr > cprm->limit) |
ecc8c772 | 823 | return 0; |
2507a4fb AV |
824 | while (nr) { |
825 | if (dump_interrupted()) | |
826 | return 0; | |
52da40ae | 827 | n = __kernel_write(file, addr, nr, &pos); |
2507a4fb AV |
828 | if (n <= 0) |
829 | return 0; | |
830 | file->f_pos = pos; | |
2c4cb043 | 831 | cprm->written += n; |
1607f09c | 832 | cprm->pos += n; |
2507a4fb AV |
833 | nr -= n; |
834 | } | |
ecc8c772 AV |
835 | return 1; |
836 | } | |
837 | EXPORT_SYMBOL(dump_emit); | |
838 | ||
9b56d543 | 839 | int dump_skip(struct coredump_params *cprm, size_t nr) |
10c28d93 | 840 | { |
9b56d543 AV |
841 | static char zeroes[PAGE_SIZE]; |
842 | struct file *file = cprm->file; | |
10c28d93 | 843 | if (file->f_op->llseek && file->f_op->llseek != no_llseek) { |
528f827e | 844 | if (dump_interrupted() || |
9b56d543 | 845 | file->f_op->llseek(file, nr, SEEK_CUR) < 0) |
10c28d93 | 846 | return 0; |
1607f09c | 847 | cprm->pos += nr; |
9b56d543 | 848 | return 1; |
10c28d93 | 849 | } else { |
9b56d543 AV |
850 | while (nr > PAGE_SIZE) { |
851 | if (!dump_emit(cprm, zeroes, PAGE_SIZE)) | |
852 | return 0; | |
853 | nr -= PAGE_SIZE; | |
10c28d93 | 854 | } |
9b56d543 | 855 | return dump_emit(cprm, zeroes, nr); |
10c28d93 | 856 | } |
10c28d93 | 857 | } |
9b56d543 | 858 | EXPORT_SYMBOL(dump_skip); |
22a8cb82 AV |
859 | |
860 | int dump_align(struct coredump_params *cprm, int align) | |
861 | { | |
1607f09c | 862 | unsigned mod = cprm->pos & (align - 1); |
22a8cb82 | 863 | if (align & (align - 1)) |
db51242d AV |
864 | return 0; |
865 | return mod ? dump_skip(cprm, align - mod) : 1; | |
22a8cb82 AV |
866 | } |
867 | EXPORT_SYMBOL(dump_align); | |
4d22c75d DK |
868 | |
869 | /* | |
870 | * Ensures that file size is big enough to contain the current file | |
871 | * postion. This prevents gdb from complaining about a truncated file | |
872 | * if the last "write" to the file was dump_skip. | |
873 | */ | |
874 | void dump_truncate(struct coredump_params *cprm) | |
875 | { | |
876 | struct file *file = cprm->file; | |
877 | loff_t offset; | |
878 | ||
879 | if (file->f_op->llseek && file->f_op->llseek != no_llseek) { | |
880 | offset = file->f_op->llseek(file, 0, SEEK_CUR); | |
881 | if (i_size_read(file->f_mapping->host) < offset) | |
882 | do_truncate(file->f_path.dentry, offset, 0, file); | |
883 | } | |
884 | } | |
885 | EXPORT_SYMBOL(dump_truncate); |