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