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