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; |
db973a72 SM |
214 | if (!(*pat_ptr)) |
215 | return -ENOMEM; | |
315c6926 | 216 | } |
10c28d93 AK |
217 | |
218 | /* Repeat as long as we have more pattern to process and more output | |
219 | space */ | |
220 | while (*pat_ptr) { | |
315c6926 PW |
221 | /* |
222 | * Split on spaces before doing template expansion so that | |
223 | * %e and %E don't get split if they have spaces in them | |
224 | */ | |
225 | if (ispipe) { | |
226 | if (isspace(*pat_ptr)) { | |
227 | was_space = true; | |
228 | pat_ptr++; | |
229 | continue; | |
230 | } else if (was_space) { | |
231 | was_space = false; | |
232 | err = cn_printf(cn, "%c", '\0'); | |
233 | if (err) | |
234 | return err; | |
235 | (*argv)[(*argc)++] = cn->used; | |
236 | } | |
237 | } | |
10c28d93 | 238 | if (*pat_ptr != '%') { |
10c28d93 AK |
239 | err = cn_printf(cn, "%c", *pat_ptr++); |
240 | } else { | |
241 | switch (*++pat_ptr) { | |
242 | /* single % at the end, drop that */ | |
243 | case 0: | |
244 | goto out; | |
245 | /* Double percent, output one percent */ | |
246 | case '%': | |
247 | err = cn_printf(cn, "%c", '%'); | |
248 | break; | |
249 | /* pid */ | |
250 | case 'p': | |
251 | pid_in_pattern = 1; | |
252 | err = cn_printf(cn, "%d", | |
253 | task_tgid_vnr(current)); | |
254 | break; | |
65aafb1e SG |
255 | /* global pid */ |
256 | case 'P': | |
257 | err = cn_printf(cn, "%d", | |
258 | task_tgid_nr(current)); | |
259 | break; | |
b03023ec ON |
260 | case 'i': |
261 | err = cn_printf(cn, "%d", | |
262 | task_pid_vnr(current)); | |
263 | break; | |
264 | case 'I': | |
265 | err = cn_printf(cn, "%d", | |
266 | task_pid_nr(current)); | |
267 | break; | |
10c28d93 AK |
268 | /* uid */ |
269 | case 'u': | |
5202efe5 NI |
270 | err = cn_printf(cn, "%u", |
271 | from_kuid(&init_user_ns, | |
272 | cred->uid)); | |
10c28d93 AK |
273 | break; |
274 | /* gid */ | |
275 | case 'g': | |
5202efe5 NI |
276 | err = cn_printf(cn, "%u", |
277 | from_kgid(&init_user_ns, | |
278 | cred->gid)); | |
10c28d93 | 279 | break; |
12a2b4b2 ON |
280 | case 'd': |
281 | err = cn_printf(cn, "%d", | |
282 | __get_dumpable(cprm->mm_flags)); | |
283 | break; | |
10c28d93 AK |
284 | /* signal that caused the coredump */ |
285 | case 's': | |
b4176b7c NI |
286 | err = cn_printf(cn, "%d", |
287 | cprm->siginfo->si_signo); | |
10c28d93 AK |
288 | break; |
289 | /* UNIX time of coredump */ | |
290 | case 't': { | |
03927c8a AB |
291 | time64_t time; |
292 | ||
293 | time = ktime_get_real_seconds(); | |
294 | err = cn_printf(cn, "%lld", time); | |
10c28d93 AK |
295 | break; |
296 | } | |
297 | /* hostname */ | |
923bed03 | 298 | case 'h': |
10c28d93 | 299 | down_read(&uts_sem); |
923bed03 | 300 | err = cn_esc_printf(cn, "%s", |
10c28d93 AK |
301 | utsname()->nodename); |
302 | up_read(&uts_sem); | |
10c28d93 | 303 | break; |
10c28d93 | 304 | /* executable */ |
923bed03 ON |
305 | case 'e': |
306 | err = cn_esc_printf(cn, "%s", current->comm); | |
10c28d93 | 307 | break; |
10c28d93 AK |
308 | case 'E': |
309 | err = cn_print_exe_file(cn); | |
310 | break; | |
311 | /* core limit size */ | |
312 | case 'c': | |
313 | err = cn_printf(cn, "%lu", | |
314 | rlimit(RLIMIT_CORE)); | |
315 | break; | |
316 | default: | |
317 | break; | |
318 | } | |
319 | ++pat_ptr; | |
320 | } | |
321 | ||
322 | if (err) | |
323 | return err; | |
324 | } | |
325 | ||
888ffc59 | 326 | out: |
10c28d93 AK |
327 | /* Backward compatibility with core_uses_pid: |
328 | * | |
329 | * If core_pattern does not include a %p (as is the default) | |
330 | * and core_uses_pid is set, then .%pid will be appended to | |
331 | * the filename. Do not do this for piped commands. */ | |
332 | if (!ispipe && !pid_in_pattern && core_uses_pid) { | |
333 | err = cn_printf(cn, ".%d", task_tgid_vnr(current)); | |
334 | if (err) | |
335 | return err; | |
336 | } | |
10c28d93 AK |
337 | return ispipe; |
338 | } | |
339 | ||
5fa534c9 | 340 | static int zap_process(struct task_struct *start, int exit_code, int flags) |
10c28d93 AK |
341 | { |
342 | struct task_struct *t; | |
343 | int nr = 0; | |
344 | ||
5fa534c9 ON |
345 | /* ignore all signals except SIGKILL, see prepare_signal() */ |
346 | start->signal->flags = SIGNAL_GROUP_COREDUMP | flags; | |
10c28d93 AK |
347 | start->signal->group_exit_code = exit_code; |
348 | start->signal->group_stop_count = 0; | |
349 | ||
d61ba589 | 350 | for_each_thread(start, t) { |
10c28d93 AK |
351 | task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); |
352 | if (t != current && t->mm) { | |
353 | sigaddset(&t->pending.signal, SIGKILL); | |
354 | signal_wake_up(t, 1); | |
355 | nr++; | |
356 | } | |
d61ba589 | 357 | } |
10c28d93 AK |
358 | |
359 | return nr; | |
360 | } | |
361 | ||
403bad72 ON |
362 | static int zap_threads(struct task_struct *tsk, struct mm_struct *mm, |
363 | struct core_state *core_state, int exit_code) | |
10c28d93 AK |
364 | { |
365 | struct task_struct *g, *p; | |
366 | unsigned long flags; | |
367 | int nr = -EAGAIN; | |
368 | ||
369 | spin_lock_irq(&tsk->sighand->siglock); | |
370 | if (!signal_group_exit(tsk->signal)) { | |
371 | mm->core_state = core_state; | |
6cd8f0ac | 372 | tsk->signal->group_exit_task = tsk; |
5fa534c9 | 373 | nr = zap_process(tsk, exit_code, 0); |
403bad72 | 374 | clear_tsk_thread_flag(tsk, TIF_SIGPENDING); |
10c28d93 AK |
375 | } |
376 | spin_unlock_irq(&tsk->sighand->siglock); | |
377 | if (unlikely(nr < 0)) | |
378 | return nr; | |
379 | ||
aed8adb7 | 380 | tsk->flags |= PF_DUMPCORE; |
10c28d93 AK |
381 | if (atomic_read(&mm->mm_users) == nr + 1) |
382 | goto done; | |
383 | /* | |
384 | * We should find and kill all tasks which use this mm, and we should | |
385 | * count them correctly into ->nr_threads. We don't take tasklist | |
386 | * lock, but this is safe wrt: | |
387 | * | |
388 | * fork: | |
389 | * None of sub-threads can fork after zap_process(leader). All | |
390 | * processes which were created before this point should be | |
391 | * visible to zap_threads() because copy_process() adds the new | |
392 | * process to the tail of init_task.tasks list, and lock/unlock | |
393 | * of ->siglock provides a memory barrier. | |
394 | * | |
395 | * do_exit: | |
c1e8d7c6 | 396 | * The caller holds mm->mmap_lock. This means that the task which |
10c28d93 AK |
397 | * uses this mm can't pass exit_mm(), so it can't exit or clear |
398 | * its ->mm. | |
399 | * | |
400 | * de_thread: | |
401 | * It does list_replace_rcu(&leader->tasks, ¤t->tasks), | |
402 | * we must see either old or new leader, this does not matter. | |
403 | * However, it can change p->sighand, so lock_task_sighand(p) | |
c1e8d7c6 | 404 | * must be used. Since p->mm != NULL and we hold ->mmap_lock |
10c28d93 AK |
405 | * it can't fail. |
406 | * | |
407 | * Note also that "g" can be the old leader with ->mm == NULL | |
408 | * and already unhashed and thus removed from ->thread_group. | |
409 | * This is OK, __unhash_process()->list_del_rcu() does not | |
410 | * clear the ->next pointer, we will find the new leader via | |
411 | * next_thread(). | |
412 | */ | |
413 | rcu_read_lock(); | |
414 | for_each_process(g) { | |
415 | if (g == tsk->group_leader) | |
416 | continue; | |
417 | if (g->flags & PF_KTHREAD) | |
418 | continue; | |
d61ba589 ON |
419 | |
420 | for_each_thread(g, p) { | |
421 | if (unlikely(!p->mm)) | |
422 | continue; | |
423 | if (unlikely(p->mm == mm)) { | |
424 | lock_task_sighand(p, &flags); | |
425 | nr += zap_process(p, exit_code, | |
426 | SIGNAL_GROUP_EXIT); | |
427 | unlock_task_sighand(p, &flags); | |
10c28d93 | 428 | } |
d61ba589 ON |
429 | break; |
430 | } | |
10c28d93 AK |
431 | } |
432 | rcu_read_unlock(); | |
433 | done: | |
434 | atomic_set(&core_state->nr_threads, nr); | |
435 | return nr; | |
436 | } | |
437 | ||
438 | static int coredump_wait(int exit_code, struct core_state *core_state) | |
439 | { | |
440 | struct task_struct *tsk = current; | |
441 | struct mm_struct *mm = tsk->mm; | |
442 | int core_waiters = -EBUSY; | |
443 | ||
444 | init_completion(&core_state->startup); | |
445 | core_state->dumper.task = tsk; | |
446 | core_state->dumper.next = NULL; | |
447 | ||
d8ed45c5 | 448 | if (mmap_write_lock_killable(mm)) |
4136c26b MH |
449 | return -EINTR; |
450 | ||
10c28d93 AK |
451 | if (!mm->core_state) |
452 | core_waiters = zap_threads(tsk, mm, core_state, exit_code); | |
d8ed45c5 | 453 | mmap_write_unlock(mm); |
10c28d93 AK |
454 | |
455 | if (core_waiters > 0) { | |
456 | struct core_thread *ptr; | |
457 | ||
70d78fe7 | 458 | freezer_do_not_count(); |
10c28d93 | 459 | wait_for_completion(&core_state->startup); |
70d78fe7 | 460 | freezer_count(); |
10c28d93 AK |
461 | /* |
462 | * Wait for all the threads to become inactive, so that | |
463 | * all the thread context (extended register state, like | |
464 | * fpu etc) gets copied to the memory. | |
465 | */ | |
466 | ptr = core_state->dumper.next; | |
467 | while (ptr != NULL) { | |
468 | wait_task_inactive(ptr->task, 0); | |
469 | ptr = ptr->next; | |
470 | } | |
471 | } | |
472 | ||
473 | return core_waiters; | |
474 | } | |
475 | ||
acdedd99 | 476 | static void coredump_finish(struct mm_struct *mm, bool core_dumped) |
10c28d93 AK |
477 | { |
478 | struct core_thread *curr, *next; | |
479 | struct task_struct *task; | |
480 | ||
6cd8f0ac | 481 | spin_lock_irq(¤t->sighand->siglock); |
acdedd99 ON |
482 | if (core_dumped && !__fatal_signal_pending(current)) |
483 | current->signal->group_exit_code |= 0x80; | |
6cd8f0ac ON |
484 | current->signal->group_exit_task = NULL; |
485 | current->signal->flags = SIGNAL_GROUP_EXIT; | |
486 | spin_unlock_irq(¤t->sighand->siglock); | |
487 | ||
10c28d93 AK |
488 | next = mm->core_state->dumper.next; |
489 | while ((curr = next) != NULL) { | |
490 | next = curr->next; | |
491 | task = curr->task; | |
492 | /* | |
493 | * see exit_mm(), curr->task must not see | |
494 | * ->task == NULL before we read ->next. | |
495 | */ | |
496 | smp_mb(); | |
497 | curr->task = NULL; | |
498 | wake_up_process(task); | |
499 | } | |
500 | ||
501 | mm->core_state = NULL; | |
502 | } | |
503 | ||
528f827e ON |
504 | static bool dump_interrupted(void) |
505 | { | |
506 | /* | |
507 | * SIGKILL or freezing() interrupt the coredumping. Perhaps we | |
508 | * can do try_to_freeze() and check __fatal_signal_pending(), | |
509 | * but then we need to teach dump_write() to restart and clear | |
510 | * TIF_SIGPENDING. | |
511 | */ | |
512 | return signal_pending(current); | |
513 | } | |
514 | ||
10c28d93 AK |
515 | static void wait_for_dump_helpers(struct file *file) |
516 | { | |
de32ec4c | 517 | struct pipe_inode_info *pipe = file->private_data; |
10c28d93 AK |
518 | |
519 | pipe_lock(pipe); | |
520 | pipe->readers++; | |
521 | pipe->writers--; | |
0ddad21d | 522 | wake_up_interruptible_sync(&pipe->rd_wait); |
dc7ee2aa ON |
523 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
524 | pipe_unlock(pipe); | |
10c28d93 | 525 | |
dc7ee2aa ON |
526 | /* |
527 | * We actually want wait_event_freezable() but then we need | |
528 | * to clear TIF_SIGPENDING and improve dump_interrupted(). | |
529 | */ | |
0ddad21d | 530 | wait_event_interruptible(pipe->rd_wait, pipe->readers == 1); |
10c28d93 | 531 | |
dc7ee2aa | 532 | pipe_lock(pipe); |
10c28d93 AK |
533 | pipe->readers--; |
534 | pipe->writers++; | |
535 | pipe_unlock(pipe); | |
10c28d93 AK |
536 | } |
537 | ||
538 | /* | |
539 | * umh_pipe_setup | |
540 | * helper function to customize the process used | |
541 | * to collect the core in userspace. Specifically | |
542 | * it sets up a pipe and installs it as fd 0 (stdin) | |
543 | * for the process. Returns 0 on success, or | |
544 | * PTR_ERR on failure. | |
545 | * Note that it also sets the core limit to 1. This | |
546 | * is a special value that we use to trap recursive | |
547 | * core dumps | |
548 | */ | |
549 | static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) | |
550 | { | |
551 | struct file *files[2]; | |
552 | struct coredump_params *cp = (struct coredump_params *)info->data; | |
553 | int err = create_pipe_files(files, 0); | |
554 | if (err) | |
555 | return err; | |
556 | ||
557 | cp->file = files[1]; | |
558 | ||
45525b26 AV |
559 | err = replace_fd(0, files[0], 0); |
560 | fput(files[0]); | |
10c28d93 AK |
561 | /* and disallow core files too */ |
562 | current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; | |
563 | ||
45525b26 | 564 | return err; |
10c28d93 AK |
565 | } |
566 | ||
ae7795bc | 567 | void do_coredump(const kernel_siginfo_t *siginfo) |
10c28d93 AK |
568 | { |
569 | struct core_state core_state; | |
570 | struct core_name cn; | |
571 | struct mm_struct *mm = current->mm; | |
572 | struct linux_binfmt * binfmt; | |
573 | const struct cred *old_cred; | |
574 | struct cred *cred; | |
575 | int retval = 0; | |
10c28d93 | 576 | int ispipe; |
315c6926 PW |
577 | size_t *argv = NULL; |
578 | int argc = 0; | |
10c28d93 | 579 | struct files_struct *displaced; |
fbb18169 JH |
580 | /* require nonrelative corefile path and be extra careful */ |
581 | bool need_suid_safe = false; | |
acdedd99 | 582 | bool core_dumped = false; |
10c28d93 AK |
583 | static atomic_t core_dump_count = ATOMIC_INIT(0); |
584 | struct coredump_params cprm = { | |
5ab1c309 | 585 | .siginfo = siginfo, |
541880d9 | 586 | .regs = signal_pt_regs(), |
10c28d93 AK |
587 | .limit = rlimit(RLIMIT_CORE), |
588 | /* | |
589 | * We must use the same mm->flags while dumping core to avoid | |
590 | * inconsistency of bit flags, since this flag is not protected | |
591 | * by any locks. | |
592 | */ | |
593 | .mm_flags = mm->flags, | |
594 | }; | |
595 | ||
5ab1c309 | 596 | audit_core_dumps(siginfo->si_signo); |
10c28d93 AK |
597 | |
598 | binfmt = mm->binfmt; | |
599 | if (!binfmt || !binfmt->core_dump) | |
600 | goto fail; | |
601 | if (!__get_dumpable(cprm.mm_flags)) | |
602 | goto fail; | |
603 | ||
604 | cred = prepare_creds(); | |
605 | if (!cred) | |
606 | goto fail; | |
607 | /* | |
608 | * We cannot trust fsuid as being the "true" uid of the process | |
609 | * nor do we know its entire history. We only know it was tainted | |
610 | * so we dump it as root in mode 2, and only into a controlled | |
611 | * environment (pipe handler or fully qualified path). | |
612 | */ | |
e579d2c2 | 613 | if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) { |
10c28d93 | 614 | /* Setuid core dump mode */ |
10c28d93 | 615 | cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */ |
fbb18169 | 616 | need_suid_safe = true; |
10c28d93 AK |
617 | } |
618 | ||
5ab1c309 | 619 | retval = coredump_wait(siginfo->si_signo, &core_state); |
10c28d93 AK |
620 | if (retval < 0) |
621 | goto fail_creds; | |
622 | ||
623 | old_cred = override_creds(cred); | |
624 | ||
315c6926 | 625 | ispipe = format_corename(&cn, &cprm, &argv, &argc); |
10c28d93 | 626 | |
fb96c475 | 627 | if (ispipe) { |
315c6926 | 628 | int argi; |
10c28d93 AK |
629 | int dump_count; |
630 | char **helper_argv; | |
907ed132 | 631 | struct subprocess_info *sub_info; |
10c28d93 AK |
632 | |
633 | if (ispipe < 0) { | |
634 | printk(KERN_WARNING "format_corename failed\n"); | |
635 | printk(KERN_WARNING "Aborting core\n"); | |
e7fd1549 | 636 | goto fail_unlock; |
10c28d93 AK |
637 | } |
638 | ||
639 | if (cprm.limit == 1) { | |
640 | /* See umh_pipe_setup() which sets RLIMIT_CORE = 1. | |
641 | * | |
642 | * Normally core limits are irrelevant to pipes, since | |
643 | * we're not writing to the file system, but we use | |
fcbc32bc | 644 | * cprm.limit of 1 here as a special value, this is a |
10c28d93 AK |
645 | * consistent way to catch recursive crashes. |
646 | * We can still crash if the core_pattern binary sets | |
647 | * RLIM_CORE = !1, but it runs as root, and can do | |
648 | * lots of stupid things. | |
649 | * | |
650 | * Note that we use task_tgid_vnr here to grab the pid | |
651 | * of the process group leader. That way we get the | |
652 | * right pid if a thread in a multi-threaded | |
653 | * core_pattern process dies. | |
654 | */ | |
655 | printk(KERN_WARNING | |
656 | "Process %d(%s) has RLIMIT_CORE set to 1\n", | |
657 | task_tgid_vnr(current), current->comm); | |
658 | printk(KERN_WARNING "Aborting core\n"); | |
659 | goto fail_unlock; | |
660 | } | |
661 | cprm.limit = RLIM_INFINITY; | |
662 | ||
663 | dump_count = atomic_inc_return(&core_dump_count); | |
664 | if (core_pipe_limit && (core_pipe_limit < dump_count)) { | |
665 | printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", | |
666 | task_tgid_vnr(current), current->comm); | |
667 | printk(KERN_WARNING "Skipping core dump\n"); | |
668 | goto fail_dropcount; | |
669 | } | |
670 | ||
315c6926 PW |
671 | helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv), |
672 | GFP_KERNEL); | |
10c28d93 AK |
673 | if (!helper_argv) { |
674 | printk(KERN_WARNING "%s failed to allocate memory\n", | |
675 | __func__); | |
676 | goto fail_dropcount; | |
677 | } | |
315c6926 PW |
678 | for (argi = 0; argi < argc; argi++) |
679 | helper_argv[argi] = cn.corename + argv[argi]; | |
680 | helper_argv[argi] = NULL; | |
10c28d93 | 681 | |
907ed132 LDM |
682 | retval = -ENOMEM; |
683 | sub_info = call_usermodehelper_setup(helper_argv[0], | |
684 | helper_argv, NULL, GFP_KERNEL, | |
685 | umh_pipe_setup, NULL, &cprm); | |
686 | if (sub_info) | |
687 | retval = call_usermodehelper_exec(sub_info, | |
688 | UMH_WAIT_EXEC); | |
689 | ||
315c6926 | 690 | kfree(helper_argv); |
10c28d93 | 691 | if (retval) { |
888ffc59 | 692 | printk(KERN_INFO "Core dump to |%s pipe failed\n", |
10c28d93 AK |
693 | cn.corename); |
694 | goto close_fail; | |
fb96c475 | 695 | } |
10c28d93 AK |
696 | } else { |
697 | struct inode *inode; | |
378c6520 JH |
698 | int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW | |
699 | O_LARGEFILE | O_EXCL; | |
10c28d93 AK |
700 | |
701 | if (cprm.limit < binfmt->min_coredump) | |
702 | goto fail_unlock; | |
703 | ||
fbb18169 | 704 | if (need_suid_safe && cn.corename[0] != '/') { |
10c28d93 AK |
705 | printk(KERN_WARNING "Pid %d(%s) can only dump core "\ |
706 | "to fully qualified path!\n", | |
707 | task_tgid_vnr(current), current->comm); | |
708 | printk(KERN_WARNING "Skipping core dump\n"); | |
709 | goto fail_unlock; | |
710 | } | |
711 | ||
fbb18169 JH |
712 | /* |
713 | * Unlink the file if it exists unless this is a SUID | |
714 | * binary - in that case, we're running around with root | |
715 | * privs and don't want to unlink another user's coredump. | |
716 | */ | |
717 | if (!need_suid_safe) { | |
fbb18169 JH |
718 | /* |
719 | * If it doesn't exist, that's fine. If there's some | |
720 | * other problem, we'll catch it at the filp_open(). | |
721 | */ | |
96271654 | 722 | do_unlinkat(AT_FDCWD, getname_kernel(cn.corename)); |
fbb18169 JH |
723 | } |
724 | ||
725 | /* | |
726 | * There is a race between unlinking and creating the | |
727 | * file, but if that causes an EEXIST here, that's | |
728 | * fine - another process raced with us while creating | |
729 | * the corefile, and the other process won. To userspace, | |
730 | * what matters is that at least one of the two processes | |
731 | * writes its coredump successfully, not which one. | |
732 | */ | |
378c6520 JH |
733 | if (need_suid_safe) { |
734 | /* | |
735 | * Using user namespaces, normal user tasks can change | |
736 | * their current->fs->root to point to arbitrary | |
737 | * directories. Since the intention of the "only dump | |
738 | * with a fully qualified path" rule is to control where | |
739 | * coredumps may be placed using root privileges, | |
740 | * current->fs->root must not be used. Instead, use the | |
741 | * root directory of init_task. | |
742 | */ | |
743 | struct path root; | |
744 | ||
745 | task_lock(&init_task); | |
746 | get_fs_root(init_task.fs, &root); | |
747 | task_unlock(&init_task); | |
748 | cprm.file = file_open_root(root.dentry, root.mnt, | |
749 | cn.corename, open_flags, 0600); | |
750 | path_put(&root); | |
751 | } else { | |
752 | cprm.file = filp_open(cn.corename, open_flags, 0600); | |
753 | } | |
10c28d93 AK |
754 | if (IS_ERR(cprm.file)) |
755 | goto fail_unlock; | |
756 | ||
496ad9aa | 757 | inode = file_inode(cprm.file); |
10c28d93 AK |
758 | if (inode->i_nlink > 1) |
759 | goto close_fail; | |
760 | if (d_unhashed(cprm.file->f_path.dentry)) | |
761 | goto close_fail; | |
762 | /* | |
763 | * AK: actually i see no reason to not allow this for named | |
764 | * pipes etc, but keep the previous behaviour for now. | |
765 | */ | |
766 | if (!S_ISREG(inode->i_mode)) | |
767 | goto close_fail; | |
768 | /* | |
40f705a7 JH |
769 | * Don't dump core if the filesystem changed owner or mode |
770 | * of the file during file creation. This is an issue when | |
771 | * a process dumps core while its cwd is e.g. on a vfat | |
772 | * filesystem. | |
10c28d93 AK |
773 | */ |
774 | if (!uid_eq(inode->i_uid, current_fsuid())) | |
775 | goto close_fail; | |
40f705a7 JH |
776 | if ((inode->i_mode & 0677) != 0600) |
777 | goto close_fail; | |
86cc0584 | 778 | if (!(cprm.file->f_mode & FMODE_CAN_WRITE)) |
10c28d93 AK |
779 | goto close_fail; |
780 | if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) | |
781 | goto close_fail; | |
782 | } | |
783 | ||
784 | /* get us an unshared descriptor table; almost always a no-op */ | |
785 | retval = unshare_files(&displaced); | |
786 | if (retval) | |
787 | goto close_fail; | |
788 | if (displaced) | |
789 | put_files_struct(displaced); | |
e86d35c3 | 790 | if (!dump_interrupted()) { |
3740d93e LC |
791 | /* |
792 | * umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would | |
793 | * have this set to NULL. | |
794 | */ | |
795 | if (!cprm.file) { | |
796 | pr_info("Core dump to |%s disabled\n", cn.corename); | |
797 | goto close_fail; | |
798 | } | |
e86d35c3 AV |
799 | file_start_write(cprm.file); |
800 | core_dumped = binfmt->core_dump(&cprm); | |
801 | file_end_write(cprm.file); | |
802 | } | |
10c28d93 AK |
803 | if (ispipe && core_pipe_limit) |
804 | wait_for_dump_helpers(cprm.file); | |
805 | close_fail: | |
806 | if (cprm.file) | |
807 | filp_close(cprm.file, NULL); | |
808 | fail_dropcount: | |
809 | if (ispipe) | |
810 | atomic_dec(&core_dump_count); | |
811 | fail_unlock: | |
315c6926 | 812 | kfree(argv); |
10c28d93 | 813 | kfree(cn.corename); |
acdedd99 | 814 | coredump_finish(mm, core_dumped); |
10c28d93 AK |
815 | revert_creds(old_cred); |
816 | fail_creds: | |
817 | put_cred(cred); | |
818 | fail: | |
819 | return; | |
820 | } | |
821 | ||
822 | /* | |
823 | * Core dumping helper functions. These are the only things you should | |
824 | * do on a core-file: use only these functions to write out all the | |
825 | * necessary info. | |
826 | */ | |
ecc8c772 AV |
827 | int dump_emit(struct coredump_params *cprm, const void *addr, int nr) |
828 | { | |
829 | struct file *file = cprm->file; | |
2507a4fb AV |
830 | loff_t pos = file->f_pos; |
831 | ssize_t n; | |
2c4cb043 | 832 | if (cprm->written + nr > cprm->limit) |
ecc8c772 | 833 | return 0; |
2507a4fb AV |
834 | while (nr) { |
835 | if (dump_interrupted()) | |
836 | return 0; | |
52da40ae | 837 | n = __kernel_write(file, addr, nr, &pos); |
2507a4fb AV |
838 | if (n <= 0) |
839 | return 0; | |
840 | file->f_pos = pos; | |
2c4cb043 | 841 | cprm->written += n; |
1607f09c | 842 | cprm->pos += n; |
2507a4fb AV |
843 | nr -= n; |
844 | } | |
ecc8c772 AV |
845 | return 1; |
846 | } | |
847 | EXPORT_SYMBOL(dump_emit); | |
848 | ||
9b56d543 | 849 | int dump_skip(struct coredump_params *cprm, size_t nr) |
10c28d93 | 850 | { |
9b56d543 AV |
851 | static char zeroes[PAGE_SIZE]; |
852 | struct file *file = cprm->file; | |
10c28d93 | 853 | if (file->f_op->llseek && file->f_op->llseek != no_llseek) { |
528f827e | 854 | if (dump_interrupted() || |
9b56d543 | 855 | file->f_op->llseek(file, nr, SEEK_CUR) < 0) |
10c28d93 | 856 | return 0; |
1607f09c | 857 | cprm->pos += nr; |
9b56d543 | 858 | return 1; |
10c28d93 | 859 | } else { |
9b56d543 AV |
860 | while (nr > PAGE_SIZE) { |
861 | if (!dump_emit(cprm, zeroes, PAGE_SIZE)) | |
862 | return 0; | |
863 | nr -= PAGE_SIZE; | |
10c28d93 | 864 | } |
9b56d543 | 865 | return dump_emit(cprm, zeroes, nr); |
10c28d93 | 866 | } |
10c28d93 | 867 | } |
9b56d543 | 868 | EXPORT_SYMBOL(dump_skip); |
22a8cb82 AV |
869 | |
870 | int dump_align(struct coredump_params *cprm, int align) | |
871 | { | |
1607f09c | 872 | unsigned mod = cprm->pos & (align - 1); |
22a8cb82 | 873 | if (align & (align - 1)) |
db51242d AV |
874 | return 0; |
875 | return mod ? dump_skip(cprm, align - mod) : 1; | |
22a8cb82 AV |
876 | } |
877 | EXPORT_SYMBOL(dump_align); | |
4d22c75d DK |
878 | |
879 | /* | |
880 | * Ensures that file size is big enough to contain the current file | |
881 | * postion. This prevents gdb from complaining about a truncated file | |
882 | * if the last "write" to the file was dump_skip. | |
883 | */ | |
884 | void dump_truncate(struct coredump_params *cprm) | |
885 | { | |
886 | struct file *file = cprm->file; | |
887 | loff_t offset; | |
888 | ||
889 | if (file->f_op->llseek && file->f_op->llseek != no_llseek) { | |
890 | offset = file->f_op->llseek(file, 0, SEEK_CUR); | |
891 | if (i_size_read(file->f_mapping->host) < offset) | |
892 | do_truncate(file->f_path.dentry, offset, 0, file); | |
893 | } | |
894 | } | |
895 | EXPORT_SYMBOL(dump_truncate); |