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Commit | Line | Data |
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10c28d93 AK |
1 | #include <linux/slab.h> |
2 | #include <linux/file.h> | |
3 | #include <linux/fdtable.h> | |
70d78fe7 | 4 | #include <linux/freezer.h> |
10c28d93 AK |
5 | #include <linux/mm.h> |
6 | #include <linux/stat.h> | |
7 | #include <linux/fcntl.h> | |
8 | #include <linux/swap.h> | |
9 | #include <linux/string.h> | |
10 | #include <linux/init.h> | |
11 | #include <linux/pagemap.h> | |
12 | #include <linux/perf_event.h> | |
13 | #include <linux/highmem.h> | |
14 | #include <linux/spinlock.h> | |
15 | #include <linux/key.h> | |
16 | #include <linux/personality.h> | |
17 | #include <linux/binfmts.h> | |
179899fd | 18 | #include <linux/coredump.h> |
f7ccbae4 | 19 | #include <linux/sched/coredump.h> |
10c28d93 AK |
20 | #include <linux/utsname.h> |
21 | #include <linux/pid_namespace.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/namei.h> | |
24 | #include <linux/mount.h> | |
25 | #include <linux/security.h> | |
26 | #include <linux/syscalls.h> | |
27 | #include <linux/tsacct_kern.h> | |
28 | #include <linux/cn_proc.h> | |
29 | #include <linux/audit.h> | |
30 | #include <linux/tracehook.h> | |
31 | #include <linux/kmod.h> | |
32 | #include <linux/fsnotify.h> | |
33 | #include <linux/fs_struct.h> | |
34 | #include <linux/pipe_fs_i.h> | |
35 | #include <linux/oom.h> | |
36 | #include <linux/compat.h> | |
378c6520 JH |
37 | #include <linux/sched.h> |
38 | #include <linux/fs.h> | |
39 | #include <linux/path.h> | |
03927c8a | 40 | #include <linux/timekeeping.h> |
10c28d93 | 41 | |
7c0f6ba6 | 42 | #include <linux/uaccess.h> |
10c28d93 AK |
43 | #include <asm/mmu_context.h> |
44 | #include <asm/tlb.h> | |
45 | #include <asm/exec.h> | |
46 | ||
47 | #include <trace/events/task.h> | |
48 | #include "internal.h" | |
49 | ||
50 | #include <trace/events/sched.h> | |
51 | ||
52 | int core_uses_pid; | |
10c28d93 | 53 | unsigned int core_pipe_limit; |
3ceadcf6 ON |
54 | char core_pattern[CORENAME_MAX_SIZE] = "core"; |
55 | static int core_name_size = CORENAME_MAX_SIZE; | |
10c28d93 AK |
56 | |
57 | struct core_name { | |
58 | char *corename; | |
59 | int used, size; | |
60 | }; | |
10c28d93 AK |
61 | |
62 | /* The maximal length of core_pattern is also specified in sysctl.c */ | |
63 | ||
3ceadcf6 | 64 | static int expand_corename(struct core_name *cn, int size) |
10c28d93 | 65 | { |
e7fd1549 | 66 | char *corename = krealloc(cn->corename, size, GFP_KERNEL); |
10c28d93 | 67 | |
e7fd1549 | 68 | if (!corename) |
10c28d93 | 69 | return -ENOMEM; |
10c28d93 | 70 | |
3ceadcf6 ON |
71 | if (size > core_name_size) /* racy but harmless */ |
72 | core_name_size = size; | |
73 | ||
74 | cn->size = ksize(corename); | |
e7fd1549 | 75 | cn->corename = corename; |
10c28d93 AK |
76 | return 0; |
77 | } | |
78 | ||
b4176b7c NI |
79 | static __printf(2, 0) int cn_vprintf(struct core_name *cn, const char *fmt, |
80 | va_list arg) | |
10c28d93 | 81 | { |
5fe9d8ca | 82 | int free, need; |
404ca80e | 83 | va_list arg_copy; |
10c28d93 | 84 | |
5fe9d8ca ON |
85 | again: |
86 | free = cn->size - cn->used; | |
404ca80e ED |
87 | |
88 | va_copy(arg_copy, arg); | |
89 | need = vsnprintf(cn->corename + cn->used, free, fmt, arg_copy); | |
90 | va_end(arg_copy); | |
91 | ||
5fe9d8ca ON |
92 | if (need < free) { |
93 | cn->used += need; | |
94 | return 0; | |
95 | } | |
10c28d93 | 96 | |
3ceadcf6 | 97 | if (!expand_corename(cn, cn->size + need - free + 1)) |
5fe9d8ca | 98 | goto again; |
10c28d93 | 99 | |
5fe9d8ca | 100 | return -ENOMEM; |
10c28d93 AK |
101 | } |
102 | ||
b4176b7c | 103 | static __printf(2, 3) int cn_printf(struct core_name *cn, const char *fmt, ...) |
bc03c691 ON |
104 | { |
105 | va_list arg; | |
106 | int ret; | |
107 | ||
108 | va_start(arg, fmt); | |
109 | ret = cn_vprintf(cn, fmt, arg); | |
110 | va_end(arg); | |
111 | ||
112 | return ret; | |
113 | } | |
114 | ||
b4176b7c NI |
115 | static __printf(2, 3) |
116 | int cn_esc_printf(struct core_name *cn, const char *fmt, ...) | |
10c28d93 | 117 | { |
923bed03 ON |
118 | int cur = cn->used; |
119 | va_list arg; | |
120 | int ret; | |
121 | ||
122 | va_start(arg, fmt); | |
123 | ret = cn_vprintf(cn, fmt, arg); | |
124 | va_end(arg); | |
125 | ||
ac94b6e3 JH |
126 | if (ret == 0) { |
127 | /* | |
128 | * Ensure that this coredump name component can't cause the | |
129 | * resulting corefile path to consist of a ".." or ".". | |
130 | */ | |
131 | if ((cn->used - cur == 1 && cn->corename[cur] == '.') || | |
132 | (cn->used - cur == 2 && cn->corename[cur] == '.' | |
133 | && cn->corename[cur+1] == '.')) | |
134 | cn->corename[cur] = '!'; | |
135 | ||
136 | /* | |
137 | * Empty names are fishy and could be used to create a "//" in a | |
138 | * corefile name, causing the coredump to happen one directory | |
139 | * level too high. Enforce that all components of the core | |
140 | * pattern are at least one character long. | |
141 | */ | |
142 | if (cn->used == cur) | |
143 | ret = cn_printf(cn, "!"); | |
144 | } | |
145 | ||
923bed03 ON |
146 | for (; cur < cn->used; ++cur) { |
147 | if (cn->corename[cur] == '/') | |
148 | cn->corename[cur] = '!'; | |
149 | } | |
150 | return ret; | |
10c28d93 AK |
151 | } |
152 | ||
153 | static int cn_print_exe_file(struct core_name *cn) | |
154 | { | |
155 | struct file *exe_file; | |
156 | char *pathbuf, *path; | |
157 | int ret; | |
158 | ||
159 | exe_file = get_mm_exe_file(current->mm); | |
923bed03 ON |
160 | if (!exe_file) |
161 | return cn_esc_printf(cn, "%s (path unknown)", current->comm); | |
10c28d93 AK |
162 | |
163 | pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY); | |
164 | if (!pathbuf) { | |
165 | ret = -ENOMEM; | |
166 | goto put_exe_file; | |
167 | } | |
168 | ||
9bf39ab2 | 169 | path = file_path(exe_file, pathbuf, PATH_MAX); |
10c28d93 AK |
170 | if (IS_ERR(path)) { |
171 | ret = PTR_ERR(path); | |
172 | goto free_buf; | |
173 | } | |
174 | ||
923bed03 | 175 | ret = cn_esc_printf(cn, "%s", path); |
10c28d93 AK |
176 | |
177 | free_buf: | |
178 | kfree(pathbuf); | |
179 | put_exe_file: | |
180 | fput(exe_file); | |
181 | return ret; | |
182 | } | |
183 | ||
184 | /* format_corename will inspect the pattern parameter, and output a | |
185 | * name into corename, which must have space for at least | |
186 | * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. | |
187 | */ | |
12a2b4b2 | 188 | static int format_corename(struct core_name *cn, struct coredump_params *cprm) |
10c28d93 AK |
189 | { |
190 | const struct cred *cred = current_cred(); | |
191 | const char *pat_ptr = core_pattern; | |
192 | int ispipe = (*pat_ptr == '|'); | |
193 | int pid_in_pattern = 0; | |
194 | int err = 0; | |
195 | ||
e7fd1549 | 196 | cn->used = 0; |
3ceadcf6 ON |
197 | cn->corename = NULL; |
198 | if (expand_corename(cn, core_name_size)) | |
10c28d93 | 199 | return -ENOMEM; |
888ffc59 ON |
200 | cn->corename[0] = '\0'; |
201 | ||
202 | if (ispipe) | |
203 | ++pat_ptr; | |
10c28d93 AK |
204 | |
205 | /* Repeat as long as we have more pattern to process and more output | |
206 | space */ | |
207 | while (*pat_ptr) { | |
208 | if (*pat_ptr != '%') { | |
10c28d93 AK |
209 | err = cn_printf(cn, "%c", *pat_ptr++); |
210 | } else { | |
211 | switch (*++pat_ptr) { | |
212 | /* single % at the end, drop that */ | |
213 | case 0: | |
214 | goto out; | |
215 | /* Double percent, output one percent */ | |
216 | case '%': | |
217 | err = cn_printf(cn, "%c", '%'); | |
218 | break; | |
219 | /* pid */ | |
220 | case 'p': | |
221 | pid_in_pattern = 1; | |
222 | err = cn_printf(cn, "%d", | |
223 | task_tgid_vnr(current)); | |
224 | break; | |
65aafb1e SG |
225 | /* global pid */ |
226 | case 'P': | |
227 | err = cn_printf(cn, "%d", | |
228 | task_tgid_nr(current)); | |
229 | break; | |
b03023ec ON |
230 | case 'i': |
231 | err = cn_printf(cn, "%d", | |
232 | task_pid_vnr(current)); | |
233 | break; | |
234 | case 'I': | |
235 | err = cn_printf(cn, "%d", | |
236 | task_pid_nr(current)); | |
237 | break; | |
10c28d93 AK |
238 | /* uid */ |
239 | case 'u': | |
5202efe5 NI |
240 | err = cn_printf(cn, "%u", |
241 | from_kuid(&init_user_ns, | |
242 | cred->uid)); | |
10c28d93 AK |
243 | break; |
244 | /* gid */ | |
245 | case 'g': | |
5202efe5 NI |
246 | err = cn_printf(cn, "%u", |
247 | from_kgid(&init_user_ns, | |
248 | cred->gid)); | |
10c28d93 | 249 | break; |
12a2b4b2 ON |
250 | case 'd': |
251 | err = cn_printf(cn, "%d", | |
252 | __get_dumpable(cprm->mm_flags)); | |
253 | break; | |
10c28d93 AK |
254 | /* signal that caused the coredump */ |
255 | case 's': | |
b4176b7c NI |
256 | err = cn_printf(cn, "%d", |
257 | cprm->siginfo->si_signo); | |
10c28d93 AK |
258 | break; |
259 | /* UNIX time of coredump */ | |
260 | case 't': { | |
03927c8a AB |
261 | time64_t time; |
262 | ||
263 | time = ktime_get_real_seconds(); | |
264 | err = cn_printf(cn, "%lld", time); | |
10c28d93 AK |
265 | break; |
266 | } | |
267 | /* hostname */ | |
923bed03 | 268 | case 'h': |
10c28d93 | 269 | down_read(&uts_sem); |
923bed03 | 270 | err = cn_esc_printf(cn, "%s", |
10c28d93 AK |
271 | utsname()->nodename); |
272 | up_read(&uts_sem); | |
10c28d93 | 273 | break; |
10c28d93 | 274 | /* executable */ |
923bed03 ON |
275 | case 'e': |
276 | err = cn_esc_printf(cn, "%s", current->comm); | |
10c28d93 | 277 | break; |
10c28d93 AK |
278 | case 'E': |
279 | err = cn_print_exe_file(cn); | |
280 | break; | |
281 | /* core limit size */ | |
282 | case 'c': | |
283 | err = cn_printf(cn, "%lu", | |
284 | rlimit(RLIMIT_CORE)); | |
285 | break; | |
286 | default: | |
287 | break; | |
288 | } | |
289 | ++pat_ptr; | |
290 | } | |
291 | ||
292 | if (err) | |
293 | return err; | |
294 | } | |
295 | ||
888ffc59 | 296 | out: |
10c28d93 AK |
297 | /* Backward compatibility with core_uses_pid: |
298 | * | |
299 | * If core_pattern does not include a %p (as is the default) | |
300 | * and core_uses_pid is set, then .%pid will be appended to | |
301 | * the filename. Do not do this for piped commands. */ | |
302 | if (!ispipe && !pid_in_pattern && core_uses_pid) { | |
303 | err = cn_printf(cn, ".%d", task_tgid_vnr(current)); | |
304 | if (err) | |
305 | return err; | |
306 | } | |
10c28d93 AK |
307 | return ispipe; |
308 | } | |
309 | ||
5fa534c9 | 310 | static int zap_process(struct task_struct *start, int exit_code, int flags) |
10c28d93 AK |
311 | { |
312 | struct task_struct *t; | |
313 | int nr = 0; | |
314 | ||
5fa534c9 ON |
315 | /* ignore all signals except SIGKILL, see prepare_signal() */ |
316 | start->signal->flags = SIGNAL_GROUP_COREDUMP | flags; | |
10c28d93 AK |
317 | start->signal->group_exit_code = exit_code; |
318 | start->signal->group_stop_count = 0; | |
319 | ||
d61ba589 | 320 | for_each_thread(start, t) { |
10c28d93 AK |
321 | task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); |
322 | if (t != current && t->mm) { | |
323 | sigaddset(&t->pending.signal, SIGKILL); | |
324 | signal_wake_up(t, 1); | |
325 | nr++; | |
326 | } | |
d61ba589 | 327 | } |
10c28d93 AK |
328 | |
329 | return nr; | |
330 | } | |
331 | ||
403bad72 ON |
332 | static int zap_threads(struct task_struct *tsk, struct mm_struct *mm, |
333 | struct core_state *core_state, int exit_code) | |
10c28d93 AK |
334 | { |
335 | struct task_struct *g, *p; | |
336 | unsigned long flags; | |
337 | int nr = -EAGAIN; | |
338 | ||
339 | spin_lock_irq(&tsk->sighand->siglock); | |
340 | if (!signal_group_exit(tsk->signal)) { | |
341 | mm->core_state = core_state; | |
6cd8f0ac | 342 | tsk->signal->group_exit_task = tsk; |
5fa534c9 | 343 | nr = zap_process(tsk, exit_code, 0); |
403bad72 | 344 | clear_tsk_thread_flag(tsk, TIF_SIGPENDING); |
10c28d93 AK |
345 | } |
346 | spin_unlock_irq(&tsk->sighand->siglock); | |
347 | if (unlikely(nr < 0)) | |
348 | return nr; | |
349 | ||
aed8adb7 | 350 | tsk->flags |= PF_DUMPCORE; |
10c28d93 AK |
351 | if (atomic_read(&mm->mm_users) == nr + 1) |
352 | goto done; | |
353 | /* | |
354 | * We should find and kill all tasks which use this mm, and we should | |
355 | * count them correctly into ->nr_threads. We don't take tasklist | |
356 | * lock, but this is safe wrt: | |
357 | * | |
358 | * fork: | |
359 | * None of sub-threads can fork after zap_process(leader). All | |
360 | * processes which were created before this point should be | |
361 | * visible to zap_threads() because copy_process() adds the new | |
362 | * process to the tail of init_task.tasks list, and lock/unlock | |
363 | * of ->siglock provides a memory barrier. | |
364 | * | |
365 | * do_exit: | |
366 | * The caller holds mm->mmap_sem. This means that the task which | |
367 | * uses this mm can't pass exit_mm(), so it can't exit or clear | |
368 | * its ->mm. | |
369 | * | |
370 | * de_thread: | |
371 | * It does list_replace_rcu(&leader->tasks, ¤t->tasks), | |
372 | * we must see either old or new leader, this does not matter. | |
373 | * However, it can change p->sighand, so lock_task_sighand(p) | |
374 | * must be used. Since p->mm != NULL and we hold ->mmap_sem | |
375 | * it can't fail. | |
376 | * | |
377 | * Note also that "g" can be the old leader with ->mm == NULL | |
378 | * and already unhashed and thus removed from ->thread_group. | |
379 | * This is OK, __unhash_process()->list_del_rcu() does not | |
380 | * clear the ->next pointer, we will find the new leader via | |
381 | * next_thread(). | |
382 | */ | |
383 | rcu_read_lock(); | |
384 | for_each_process(g) { | |
385 | if (g == tsk->group_leader) | |
386 | continue; | |
387 | if (g->flags & PF_KTHREAD) | |
388 | continue; | |
d61ba589 ON |
389 | |
390 | for_each_thread(g, p) { | |
391 | if (unlikely(!p->mm)) | |
392 | continue; | |
393 | if (unlikely(p->mm == mm)) { | |
394 | lock_task_sighand(p, &flags); | |
395 | nr += zap_process(p, exit_code, | |
396 | SIGNAL_GROUP_EXIT); | |
397 | unlock_task_sighand(p, &flags); | |
10c28d93 | 398 | } |
d61ba589 ON |
399 | break; |
400 | } | |
10c28d93 AK |
401 | } |
402 | rcu_read_unlock(); | |
403 | done: | |
404 | atomic_set(&core_state->nr_threads, nr); | |
405 | return nr; | |
406 | } | |
407 | ||
408 | static int coredump_wait(int exit_code, struct core_state *core_state) | |
409 | { | |
410 | struct task_struct *tsk = current; | |
411 | struct mm_struct *mm = tsk->mm; | |
412 | int core_waiters = -EBUSY; | |
413 | ||
414 | init_completion(&core_state->startup); | |
415 | core_state->dumper.task = tsk; | |
416 | core_state->dumper.next = NULL; | |
417 | ||
4136c26b MH |
418 | if (down_write_killable(&mm->mmap_sem)) |
419 | return -EINTR; | |
420 | ||
10c28d93 AK |
421 | if (!mm->core_state) |
422 | core_waiters = zap_threads(tsk, mm, core_state, exit_code); | |
423 | up_write(&mm->mmap_sem); | |
424 | ||
425 | if (core_waiters > 0) { | |
426 | struct core_thread *ptr; | |
427 | ||
70d78fe7 | 428 | freezer_do_not_count(); |
10c28d93 | 429 | wait_for_completion(&core_state->startup); |
70d78fe7 | 430 | freezer_count(); |
10c28d93 AK |
431 | /* |
432 | * Wait for all the threads to become inactive, so that | |
433 | * all the thread context (extended register state, like | |
434 | * fpu etc) gets copied to the memory. | |
435 | */ | |
436 | ptr = core_state->dumper.next; | |
437 | while (ptr != NULL) { | |
438 | wait_task_inactive(ptr->task, 0); | |
439 | ptr = ptr->next; | |
440 | } | |
441 | } | |
442 | ||
443 | return core_waiters; | |
444 | } | |
445 | ||
acdedd99 | 446 | static void coredump_finish(struct mm_struct *mm, bool core_dumped) |
10c28d93 AK |
447 | { |
448 | struct core_thread *curr, *next; | |
449 | struct task_struct *task; | |
450 | ||
6cd8f0ac | 451 | spin_lock_irq(¤t->sighand->siglock); |
acdedd99 ON |
452 | if (core_dumped && !__fatal_signal_pending(current)) |
453 | current->signal->group_exit_code |= 0x80; | |
6cd8f0ac ON |
454 | current->signal->group_exit_task = NULL; |
455 | current->signal->flags = SIGNAL_GROUP_EXIT; | |
456 | spin_unlock_irq(¤t->sighand->siglock); | |
457 | ||
10c28d93 AK |
458 | next = mm->core_state->dumper.next; |
459 | while ((curr = next) != NULL) { | |
460 | next = curr->next; | |
461 | task = curr->task; | |
462 | /* | |
463 | * see exit_mm(), curr->task must not see | |
464 | * ->task == NULL before we read ->next. | |
465 | */ | |
466 | smp_mb(); | |
467 | curr->task = NULL; | |
468 | wake_up_process(task); | |
469 | } | |
470 | ||
471 | mm->core_state = NULL; | |
472 | } | |
473 | ||
528f827e ON |
474 | static bool dump_interrupted(void) |
475 | { | |
476 | /* | |
477 | * SIGKILL or freezing() interrupt the coredumping. Perhaps we | |
478 | * can do try_to_freeze() and check __fatal_signal_pending(), | |
479 | * but then we need to teach dump_write() to restart and clear | |
480 | * TIF_SIGPENDING. | |
481 | */ | |
482 | return signal_pending(current); | |
483 | } | |
484 | ||
10c28d93 AK |
485 | static void wait_for_dump_helpers(struct file *file) |
486 | { | |
de32ec4c | 487 | struct pipe_inode_info *pipe = file->private_data; |
10c28d93 AK |
488 | |
489 | pipe_lock(pipe); | |
490 | pipe->readers++; | |
491 | pipe->writers--; | |
dc7ee2aa ON |
492 | wake_up_interruptible_sync(&pipe->wait); |
493 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
494 | pipe_unlock(pipe); | |
10c28d93 | 495 | |
dc7ee2aa ON |
496 | /* |
497 | * We actually want wait_event_freezable() but then we need | |
498 | * to clear TIF_SIGPENDING and improve dump_interrupted(). | |
499 | */ | |
500 | wait_event_interruptible(pipe->wait, pipe->readers == 1); | |
10c28d93 | 501 | |
dc7ee2aa | 502 | pipe_lock(pipe); |
10c28d93 AK |
503 | pipe->readers--; |
504 | pipe->writers++; | |
505 | pipe_unlock(pipe); | |
10c28d93 AK |
506 | } |
507 | ||
508 | /* | |
509 | * umh_pipe_setup | |
510 | * helper function to customize the process used | |
511 | * to collect the core in userspace. Specifically | |
512 | * it sets up a pipe and installs it as fd 0 (stdin) | |
513 | * for the process. Returns 0 on success, or | |
514 | * PTR_ERR on failure. | |
515 | * Note that it also sets the core limit to 1. This | |
516 | * is a special value that we use to trap recursive | |
517 | * core dumps | |
518 | */ | |
519 | static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) | |
520 | { | |
521 | struct file *files[2]; | |
522 | struct coredump_params *cp = (struct coredump_params *)info->data; | |
523 | int err = create_pipe_files(files, 0); | |
524 | if (err) | |
525 | return err; | |
526 | ||
527 | cp->file = files[1]; | |
528 | ||
45525b26 AV |
529 | err = replace_fd(0, files[0], 0); |
530 | fput(files[0]); | |
10c28d93 AK |
531 | /* and disallow core files too */ |
532 | current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; | |
533 | ||
45525b26 | 534 | return err; |
10c28d93 AK |
535 | } |
536 | ||
ec57941e | 537 | void do_coredump(const siginfo_t *siginfo) |
10c28d93 AK |
538 | { |
539 | struct core_state core_state; | |
540 | struct core_name cn; | |
541 | struct mm_struct *mm = current->mm; | |
542 | struct linux_binfmt * binfmt; | |
543 | const struct cred *old_cred; | |
544 | struct cred *cred; | |
545 | int retval = 0; | |
10c28d93 AK |
546 | int ispipe; |
547 | struct files_struct *displaced; | |
fbb18169 JH |
548 | /* require nonrelative corefile path and be extra careful */ |
549 | bool need_suid_safe = false; | |
acdedd99 | 550 | bool core_dumped = false; |
10c28d93 AK |
551 | static atomic_t core_dump_count = ATOMIC_INIT(0); |
552 | struct coredump_params cprm = { | |
5ab1c309 | 553 | .siginfo = siginfo, |
541880d9 | 554 | .regs = signal_pt_regs(), |
10c28d93 AK |
555 | .limit = rlimit(RLIMIT_CORE), |
556 | /* | |
557 | * We must use the same mm->flags while dumping core to avoid | |
558 | * inconsistency of bit flags, since this flag is not protected | |
559 | * by any locks. | |
560 | */ | |
561 | .mm_flags = mm->flags, | |
562 | }; | |
563 | ||
5ab1c309 | 564 | audit_core_dumps(siginfo->si_signo); |
10c28d93 AK |
565 | |
566 | binfmt = mm->binfmt; | |
567 | if (!binfmt || !binfmt->core_dump) | |
568 | goto fail; | |
569 | if (!__get_dumpable(cprm.mm_flags)) | |
570 | goto fail; | |
571 | ||
572 | cred = prepare_creds(); | |
573 | if (!cred) | |
574 | goto fail; | |
575 | /* | |
576 | * We cannot trust fsuid as being the "true" uid of the process | |
577 | * nor do we know its entire history. We only know it was tainted | |
578 | * so we dump it as root in mode 2, and only into a controlled | |
579 | * environment (pipe handler or fully qualified path). | |
580 | */ | |
e579d2c2 | 581 | if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) { |
10c28d93 | 582 | /* Setuid core dump mode */ |
10c28d93 | 583 | cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */ |
fbb18169 | 584 | need_suid_safe = true; |
10c28d93 AK |
585 | } |
586 | ||
5ab1c309 | 587 | retval = coredump_wait(siginfo->si_signo, &core_state); |
10c28d93 AK |
588 | if (retval < 0) |
589 | goto fail_creds; | |
590 | ||
591 | old_cred = override_creds(cred); | |
592 | ||
12a2b4b2 | 593 | ispipe = format_corename(&cn, &cprm); |
10c28d93 | 594 | |
fb96c475 | 595 | if (ispipe) { |
10c28d93 AK |
596 | int dump_count; |
597 | char **helper_argv; | |
907ed132 | 598 | struct subprocess_info *sub_info; |
10c28d93 AK |
599 | |
600 | if (ispipe < 0) { | |
601 | printk(KERN_WARNING "format_corename failed\n"); | |
602 | printk(KERN_WARNING "Aborting core\n"); | |
e7fd1549 | 603 | goto fail_unlock; |
10c28d93 AK |
604 | } |
605 | ||
606 | if (cprm.limit == 1) { | |
607 | /* See umh_pipe_setup() which sets RLIMIT_CORE = 1. | |
608 | * | |
609 | * Normally core limits are irrelevant to pipes, since | |
610 | * we're not writing to the file system, but we use | |
fcbc32bc | 611 | * cprm.limit of 1 here as a special value, this is a |
10c28d93 AK |
612 | * consistent way to catch recursive crashes. |
613 | * We can still crash if the core_pattern binary sets | |
614 | * RLIM_CORE = !1, but it runs as root, and can do | |
615 | * lots of stupid things. | |
616 | * | |
617 | * Note that we use task_tgid_vnr here to grab the pid | |
618 | * of the process group leader. That way we get the | |
619 | * right pid if a thread in a multi-threaded | |
620 | * core_pattern process dies. | |
621 | */ | |
622 | printk(KERN_WARNING | |
623 | "Process %d(%s) has RLIMIT_CORE set to 1\n", | |
624 | task_tgid_vnr(current), current->comm); | |
625 | printk(KERN_WARNING "Aborting core\n"); | |
626 | goto fail_unlock; | |
627 | } | |
628 | cprm.limit = RLIM_INFINITY; | |
629 | ||
630 | dump_count = atomic_inc_return(&core_dump_count); | |
631 | if (core_pipe_limit && (core_pipe_limit < dump_count)) { | |
632 | printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", | |
633 | task_tgid_vnr(current), current->comm); | |
634 | printk(KERN_WARNING "Skipping core dump\n"); | |
635 | goto fail_dropcount; | |
636 | } | |
637 | ||
888ffc59 | 638 | helper_argv = argv_split(GFP_KERNEL, cn.corename, NULL); |
10c28d93 AK |
639 | if (!helper_argv) { |
640 | printk(KERN_WARNING "%s failed to allocate memory\n", | |
641 | __func__); | |
642 | goto fail_dropcount; | |
643 | } | |
644 | ||
907ed132 LDM |
645 | retval = -ENOMEM; |
646 | sub_info = call_usermodehelper_setup(helper_argv[0], | |
647 | helper_argv, NULL, GFP_KERNEL, | |
648 | umh_pipe_setup, NULL, &cprm); | |
649 | if (sub_info) | |
650 | retval = call_usermodehelper_exec(sub_info, | |
651 | UMH_WAIT_EXEC); | |
652 | ||
10c28d93 AK |
653 | argv_free(helper_argv); |
654 | if (retval) { | |
888ffc59 | 655 | printk(KERN_INFO "Core dump to |%s pipe failed\n", |
10c28d93 AK |
656 | cn.corename); |
657 | goto close_fail; | |
fb96c475 | 658 | } |
10c28d93 AK |
659 | } else { |
660 | struct inode *inode; | |
378c6520 JH |
661 | int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW | |
662 | O_LARGEFILE | O_EXCL; | |
10c28d93 AK |
663 | |
664 | if (cprm.limit < binfmt->min_coredump) | |
665 | goto fail_unlock; | |
666 | ||
fbb18169 | 667 | if (need_suid_safe && cn.corename[0] != '/') { |
10c28d93 AK |
668 | printk(KERN_WARNING "Pid %d(%s) can only dump core "\ |
669 | "to fully qualified path!\n", | |
670 | task_tgid_vnr(current), current->comm); | |
671 | printk(KERN_WARNING "Skipping core dump\n"); | |
672 | goto fail_unlock; | |
673 | } | |
674 | ||
fbb18169 JH |
675 | /* |
676 | * Unlink the file if it exists unless this is a SUID | |
677 | * binary - in that case, we're running around with root | |
678 | * privs and don't want to unlink another user's coredump. | |
679 | */ | |
680 | if (!need_suid_safe) { | |
681 | mm_segment_t old_fs; | |
682 | ||
683 | old_fs = get_fs(); | |
684 | set_fs(KERNEL_DS); | |
685 | /* | |
686 | * If it doesn't exist, that's fine. If there's some | |
687 | * other problem, we'll catch it at the filp_open(). | |
688 | */ | |
689 | (void) sys_unlink((const char __user *)cn.corename); | |
690 | set_fs(old_fs); | |
691 | } | |
692 | ||
693 | /* | |
694 | * There is a race between unlinking and creating the | |
695 | * file, but if that causes an EEXIST here, that's | |
696 | * fine - another process raced with us while creating | |
697 | * the corefile, and the other process won. To userspace, | |
698 | * what matters is that at least one of the two processes | |
699 | * writes its coredump successfully, not which one. | |
700 | */ | |
378c6520 JH |
701 | if (need_suid_safe) { |
702 | /* | |
703 | * Using user namespaces, normal user tasks can change | |
704 | * their current->fs->root to point to arbitrary | |
705 | * directories. Since the intention of the "only dump | |
706 | * with a fully qualified path" rule is to control where | |
707 | * coredumps may be placed using root privileges, | |
708 | * current->fs->root must not be used. Instead, use the | |
709 | * root directory of init_task. | |
710 | */ | |
711 | struct path root; | |
712 | ||
713 | task_lock(&init_task); | |
714 | get_fs_root(init_task.fs, &root); | |
715 | task_unlock(&init_task); | |
716 | cprm.file = file_open_root(root.dentry, root.mnt, | |
717 | cn.corename, open_flags, 0600); | |
718 | path_put(&root); | |
719 | } else { | |
720 | cprm.file = filp_open(cn.corename, open_flags, 0600); | |
721 | } | |
10c28d93 AK |
722 | if (IS_ERR(cprm.file)) |
723 | goto fail_unlock; | |
724 | ||
496ad9aa | 725 | inode = file_inode(cprm.file); |
10c28d93 AK |
726 | if (inode->i_nlink > 1) |
727 | goto close_fail; | |
728 | if (d_unhashed(cprm.file->f_path.dentry)) | |
729 | goto close_fail; | |
730 | /* | |
731 | * AK: actually i see no reason to not allow this for named | |
732 | * pipes etc, but keep the previous behaviour for now. | |
733 | */ | |
734 | if (!S_ISREG(inode->i_mode)) | |
735 | goto close_fail; | |
736 | /* | |
40f705a7 JH |
737 | * Don't dump core if the filesystem changed owner or mode |
738 | * of the file during file creation. This is an issue when | |
739 | * a process dumps core while its cwd is e.g. on a vfat | |
740 | * filesystem. | |
10c28d93 AK |
741 | */ |
742 | if (!uid_eq(inode->i_uid, current_fsuid())) | |
743 | goto close_fail; | |
40f705a7 JH |
744 | if ((inode->i_mode & 0677) != 0600) |
745 | goto close_fail; | |
86cc0584 | 746 | if (!(cprm.file->f_mode & FMODE_CAN_WRITE)) |
10c28d93 AK |
747 | goto close_fail; |
748 | if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) | |
749 | goto close_fail; | |
750 | } | |
751 | ||
752 | /* get us an unshared descriptor table; almost always a no-op */ | |
753 | retval = unshare_files(&displaced); | |
754 | if (retval) | |
755 | goto close_fail; | |
756 | if (displaced) | |
757 | put_files_struct(displaced); | |
e86d35c3 AV |
758 | if (!dump_interrupted()) { |
759 | file_start_write(cprm.file); | |
760 | core_dumped = binfmt->core_dump(&cprm); | |
761 | file_end_write(cprm.file); | |
762 | } | |
10c28d93 AK |
763 | if (ispipe && core_pipe_limit) |
764 | wait_for_dump_helpers(cprm.file); | |
765 | close_fail: | |
766 | if (cprm.file) | |
767 | filp_close(cprm.file, NULL); | |
768 | fail_dropcount: | |
769 | if (ispipe) | |
770 | atomic_dec(&core_dump_count); | |
771 | fail_unlock: | |
772 | kfree(cn.corename); | |
acdedd99 | 773 | coredump_finish(mm, core_dumped); |
10c28d93 AK |
774 | revert_creds(old_cred); |
775 | fail_creds: | |
776 | put_cred(cred); | |
777 | fail: | |
778 | return; | |
779 | } | |
780 | ||
781 | /* | |
782 | * Core dumping helper functions. These are the only things you should | |
783 | * do on a core-file: use only these functions to write out all the | |
784 | * necessary info. | |
785 | */ | |
ecc8c772 AV |
786 | int dump_emit(struct coredump_params *cprm, const void *addr, int nr) |
787 | { | |
788 | struct file *file = cprm->file; | |
2507a4fb AV |
789 | loff_t pos = file->f_pos; |
790 | ssize_t n; | |
2c4cb043 | 791 | if (cprm->written + nr > cprm->limit) |
ecc8c772 | 792 | return 0; |
2507a4fb AV |
793 | while (nr) { |
794 | if (dump_interrupted()) | |
795 | return 0; | |
52da40ae | 796 | n = __kernel_write(file, addr, nr, &pos); |
2507a4fb AV |
797 | if (n <= 0) |
798 | return 0; | |
799 | file->f_pos = pos; | |
2c4cb043 | 800 | cprm->written += n; |
1607f09c | 801 | cprm->pos += n; |
2507a4fb AV |
802 | nr -= n; |
803 | } | |
ecc8c772 AV |
804 | return 1; |
805 | } | |
806 | EXPORT_SYMBOL(dump_emit); | |
807 | ||
9b56d543 | 808 | int dump_skip(struct coredump_params *cprm, size_t nr) |
10c28d93 | 809 | { |
9b56d543 AV |
810 | static char zeroes[PAGE_SIZE]; |
811 | struct file *file = cprm->file; | |
10c28d93 | 812 | if (file->f_op->llseek && file->f_op->llseek != no_llseek) { |
528f827e | 813 | if (dump_interrupted() || |
9b56d543 | 814 | file->f_op->llseek(file, nr, SEEK_CUR) < 0) |
10c28d93 | 815 | return 0; |
1607f09c | 816 | cprm->pos += nr; |
9b56d543 | 817 | return 1; |
10c28d93 | 818 | } else { |
9b56d543 AV |
819 | while (nr > PAGE_SIZE) { |
820 | if (!dump_emit(cprm, zeroes, PAGE_SIZE)) | |
821 | return 0; | |
822 | nr -= PAGE_SIZE; | |
10c28d93 | 823 | } |
9b56d543 | 824 | return dump_emit(cprm, zeroes, nr); |
10c28d93 | 825 | } |
10c28d93 | 826 | } |
9b56d543 | 827 | EXPORT_SYMBOL(dump_skip); |
22a8cb82 AV |
828 | |
829 | int dump_align(struct coredump_params *cprm, int align) | |
830 | { | |
1607f09c | 831 | unsigned mod = cprm->pos & (align - 1); |
22a8cb82 | 832 | if (align & (align - 1)) |
db51242d AV |
833 | return 0; |
834 | return mod ? dump_skip(cprm, align - mod) : 1; | |
22a8cb82 AV |
835 | } |
836 | EXPORT_SYMBOL(dump_align); | |
4d22c75d DK |
837 | |
838 | /* | |
839 | * Ensures that file size is big enough to contain the current file | |
840 | * postion. This prevents gdb from complaining about a truncated file | |
841 | * if the last "write" to the file was dump_skip. | |
842 | */ | |
843 | void dump_truncate(struct coredump_params *cprm) | |
844 | { | |
845 | struct file *file = cprm->file; | |
846 | loff_t offset; | |
847 | ||
848 | if (file->f_op->llseek && file->f_op->llseek != no_llseek) { | |
849 | offset = file->f_op->llseek(file, 0, SEEK_CUR); | |
850 | if (i_size_read(file->f_mapping->host) < offset) | |
851 | do_truncate(file->f_path.dentry, offset, 0, file); | |
852 | } | |
853 | } | |
854 | EXPORT_SYMBOL(dump_truncate); |