blob: 72f816d6cad99d4d1f81433e928d42e540295188 [file] [log] [blame]
Alex Kelly10c28d92012-09-26 21:52:08 -04001#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>
Alex Kelly179899f2012-10-04 17:15:24 -070017#include <linux/coredump.h>
Alex Kelly10c28d92012-09-26 21:52:08 -040018#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>
35
36#include <asm/uaccess.h>
37#include <asm/mmu_context.h>
38#include <asm/tlb.h>
39#include <asm/exec.h>
40
41#include <trace/events/task.h>
42#include "internal.h"
Alex Kelly179899f2012-10-04 17:15:24 -070043#include "coredump.h"
Alex Kelly10c28d92012-09-26 21:52:08 -040044
45#include <trace/events/sched.h>
46
47int core_uses_pid;
Alex Kelly10c28d92012-09-26 21:52:08 -040048unsigned int core_pipe_limit;
Oleg Nesterov3ceadcf2013-07-03 15:08:22 -070049char core_pattern[CORENAME_MAX_SIZE] = "core";
50static int core_name_size = CORENAME_MAX_SIZE;
Alex Kelly10c28d92012-09-26 21:52:08 -040051
52struct core_name {
53 char *corename;
54 int used, size;
55};
Alex Kelly10c28d92012-09-26 21:52:08 -040056
57/* The maximal length of core_pattern is also specified in sysctl.c */
58
Oleg Nesterov3ceadcf2013-07-03 15:08:22 -070059static int expand_corename(struct core_name *cn, int size)
Alex Kelly10c28d92012-09-26 21:52:08 -040060{
Oleg Nesterove7fd1542013-07-03 15:08:16 -070061 char *corename = krealloc(cn->corename, size, GFP_KERNEL);
Alex Kelly10c28d92012-09-26 21:52:08 -040062
Oleg Nesterove7fd1542013-07-03 15:08:16 -070063 if (!corename)
Alex Kelly10c28d92012-09-26 21:52:08 -040064 return -ENOMEM;
Alex Kelly10c28d92012-09-26 21:52:08 -040065
Oleg Nesterov3ceadcf2013-07-03 15:08:22 -070066 if (size > core_name_size) /* racy but harmless */
67 core_name_size = size;
68
69 cn->size = ksize(corename);
Oleg Nesterove7fd1542013-07-03 15:08:16 -070070 cn->corename = corename;
Alex Kelly10c28d92012-09-26 21:52:08 -040071 return 0;
72}
73
Oleg Nesterovbc03c692013-07-03 15:08:17 -070074static int cn_vprintf(struct core_name *cn, const char *fmt, va_list arg)
Alex Kelly10c28d92012-09-26 21:52:08 -040075{
Oleg Nesterov5fe9d8c2013-07-03 15:08:19 -070076 int free, need;
Alex Kelly10c28d92012-09-26 21:52:08 -040077
Oleg Nesterov5fe9d8c2013-07-03 15:08:19 -070078again:
79 free = cn->size - cn->used;
80 need = vsnprintf(cn->corename + cn->used, free, fmt, arg);
81 if (need < free) {
82 cn->used += need;
83 return 0;
84 }
Alex Kelly10c28d92012-09-26 21:52:08 -040085
Oleg Nesterov3ceadcf2013-07-03 15:08:22 -070086 if (!expand_corename(cn, cn->size + need - free + 1))
Oleg Nesterov5fe9d8c2013-07-03 15:08:19 -070087 goto again;
Alex Kelly10c28d92012-09-26 21:52:08 -040088
Oleg Nesterov5fe9d8c2013-07-03 15:08:19 -070089 return -ENOMEM;
Alex Kelly10c28d92012-09-26 21:52:08 -040090}
91
Oleg Nesterovbc03c692013-07-03 15:08:17 -070092static int cn_printf(struct core_name *cn, const char *fmt, ...)
93{
94 va_list arg;
95 int ret;
96
97 va_start(arg, fmt);
98 ret = cn_vprintf(cn, fmt, arg);
99 va_end(arg);
100
101 return ret;
102}
103
Oleg Nesterov923bed032013-07-03 15:08:20 -0700104static int cn_esc_printf(struct core_name *cn, const char *fmt, ...)
Alex Kelly10c28d92012-09-26 21:52:08 -0400105{
Oleg Nesterov923bed032013-07-03 15:08:20 -0700106 int cur = cn->used;
107 va_list arg;
108 int ret;
109
110 va_start(arg, fmt);
111 ret = cn_vprintf(cn, fmt, arg);
112 va_end(arg);
113
114 for (; cur < cn->used; ++cur) {
115 if (cn->corename[cur] == '/')
116 cn->corename[cur] = '!';
117 }
118 return ret;
Alex Kelly10c28d92012-09-26 21:52:08 -0400119}
120
121static int cn_print_exe_file(struct core_name *cn)
122{
123 struct file *exe_file;
124 char *pathbuf, *path;
125 int ret;
126
127 exe_file = get_mm_exe_file(current->mm);
Oleg Nesterov923bed032013-07-03 15:08:20 -0700128 if (!exe_file)
129 return cn_esc_printf(cn, "%s (path unknown)", current->comm);
Alex Kelly10c28d92012-09-26 21:52:08 -0400130
131 pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
132 if (!pathbuf) {
133 ret = -ENOMEM;
134 goto put_exe_file;
135 }
136
137 path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
138 if (IS_ERR(path)) {
139 ret = PTR_ERR(path);
140 goto free_buf;
141 }
142
Oleg Nesterov923bed032013-07-03 15:08:20 -0700143 ret = cn_esc_printf(cn, "%s", path);
Alex Kelly10c28d92012-09-26 21:52:08 -0400144
145free_buf:
146 kfree(pathbuf);
147put_exe_file:
148 fput(exe_file);
149 return ret;
150}
151
152/* format_corename will inspect the pattern parameter, and output a
153 * name into corename, which must have space for at least
154 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
155 */
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700156static int format_corename(struct core_name *cn, struct coredump_params *cprm)
Alex Kelly10c28d92012-09-26 21:52:08 -0400157{
158 const struct cred *cred = current_cred();
159 const char *pat_ptr = core_pattern;
160 int ispipe = (*pat_ptr == '|');
161 int pid_in_pattern = 0;
162 int err = 0;
163
Oleg Nesterove7fd1542013-07-03 15:08:16 -0700164 cn->used = 0;
Oleg Nesterov3ceadcf2013-07-03 15:08:22 -0700165 cn->corename = NULL;
166 if (expand_corename(cn, core_name_size))
Alex Kelly10c28d92012-09-26 21:52:08 -0400167 return -ENOMEM;
Oleg Nesterov888ffc52013-07-03 15:08:23 -0700168 cn->corename[0] = '\0';
169
170 if (ispipe)
171 ++pat_ptr;
Alex Kelly10c28d92012-09-26 21:52:08 -0400172
173 /* Repeat as long as we have more pattern to process and more output
174 space */
175 while (*pat_ptr) {
176 if (*pat_ptr != '%') {
Alex Kelly10c28d92012-09-26 21:52:08 -0400177 err = cn_printf(cn, "%c", *pat_ptr++);
178 } else {
179 switch (*++pat_ptr) {
180 /* single % at the end, drop that */
181 case 0:
182 goto out;
183 /* Double percent, output one percent */
184 case '%':
185 err = cn_printf(cn, "%c", '%');
186 break;
187 /* pid */
188 case 'p':
189 pid_in_pattern = 1;
190 err = cn_printf(cn, "%d",
191 task_tgid_vnr(current));
192 break;
193 /* uid */
194 case 'u':
195 err = cn_printf(cn, "%d", cred->uid);
196 break;
197 /* gid */
198 case 'g':
199 err = cn_printf(cn, "%d", cred->gid);
200 break;
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700201 case 'd':
202 err = cn_printf(cn, "%d",
203 __get_dumpable(cprm->mm_flags));
204 break;
Alex Kelly10c28d92012-09-26 21:52:08 -0400205 /* signal that caused the coredump */
206 case 's':
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700207 err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
Alex Kelly10c28d92012-09-26 21:52:08 -0400208 break;
209 /* UNIX time of coredump */
210 case 't': {
211 struct timeval tv;
212 do_gettimeofday(&tv);
213 err = cn_printf(cn, "%lu", tv.tv_sec);
214 break;
215 }
216 /* hostname */
Oleg Nesterov923bed032013-07-03 15:08:20 -0700217 case 'h':
Alex Kelly10c28d92012-09-26 21:52:08 -0400218 down_read(&uts_sem);
Oleg Nesterov923bed032013-07-03 15:08:20 -0700219 err = cn_esc_printf(cn, "%s",
Alex Kelly10c28d92012-09-26 21:52:08 -0400220 utsname()->nodename);
221 up_read(&uts_sem);
Alex Kelly10c28d92012-09-26 21:52:08 -0400222 break;
Alex Kelly10c28d92012-09-26 21:52:08 -0400223 /* executable */
Oleg Nesterov923bed032013-07-03 15:08:20 -0700224 case 'e':
225 err = cn_esc_printf(cn, "%s", current->comm);
Alex Kelly10c28d92012-09-26 21:52:08 -0400226 break;
Alex Kelly10c28d92012-09-26 21:52:08 -0400227 case 'E':
228 err = cn_print_exe_file(cn);
229 break;
230 /* core limit size */
231 case 'c':
232 err = cn_printf(cn, "%lu",
233 rlimit(RLIMIT_CORE));
234 break;
235 default:
236 break;
237 }
238 ++pat_ptr;
239 }
240
241 if (err)
242 return err;
243 }
244
Oleg Nesterov888ffc52013-07-03 15:08:23 -0700245out:
Alex Kelly10c28d92012-09-26 21:52:08 -0400246 /* Backward compatibility with core_uses_pid:
247 *
248 * If core_pattern does not include a %p (as is the default)
249 * and core_uses_pid is set, then .%pid will be appended to
250 * the filename. Do not do this for piped commands. */
251 if (!ispipe && !pid_in_pattern && core_uses_pid) {
252 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
253 if (err)
254 return err;
255 }
Alex Kelly10c28d92012-09-26 21:52:08 -0400256 return ispipe;
257}
258
259static int zap_process(struct task_struct *start, int exit_code)
260{
261 struct task_struct *t;
262 int nr = 0;
263
Alex Kelly10c28d92012-09-26 21:52:08 -0400264 start->signal->group_exit_code = exit_code;
265 start->signal->group_stop_count = 0;
266
267 t = start;
268 do {
269 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
270 if (t != current && t->mm) {
271 sigaddset(&t->pending.signal, SIGKILL);
272 signal_wake_up(t, 1);
273 nr++;
274 }
275 } while_each_thread(start, t);
276
277 return nr;
278}
279
Oleg Nesterov403bad72013-04-30 15:28:10 -0700280static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
281 struct core_state *core_state, int exit_code)
Alex Kelly10c28d92012-09-26 21:52:08 -0400282{
283 struct task_struct *g, *p;
284 unsigned long flags;
285 int nr = -EAGAIN;
286
287 spin_lock_irq(&tsk->sighand->siglock);
288 if (!signal_group_exit(tsk->signal)) {
289 mm->core_state = core_state;
290 nr = zap_process(tsk, exit_code);
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700291 tsk->signal->group_exit_task = tsk;
Oleg Nesterov403bad72013-04-30 15:28:10 -0700292 /* ignore all signals except SIGKILL, see prepare_signal() */
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700293 tsk->signal->flags = SIGNAL_GROUP_COREDUMP;
Oleg Nesterov403bad72013-04-30 15:28:10 -0700294 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
Alex Kelly10c28d92012-09-26 21:52:08 -0400295 }
296 spin_unlock_irq(&tsk->sighand->siglock);
297 if (unlikely(nr < 0))
298 return nr;
299
Oleg Nesterov079148b2013-04-30 15:28:16 -0700300 tsk->flags = PF_DUMPCORE;
Alex Kelly10c28d92012-09-26 21:52:08 -0400301 if (atomic_read(&mm->mm_users) == nr + 1)
302 goto done;
303 /*
304 * We should find and kill all tasks which use this mm, and we should
305 * count them correctly into ->nr_threads. We don't take tasklist
306 * lock, but this is safe wrt:
307 *
308 * fork:
309 * None of sub-threads can fork after zap_process(leader). All
310 * processes which were created before this point should be
311 * visible to zap_threads() because copy_process() adds the new
312 * process to the tail of init_task.tasks list, and lock/unlock
313 * of ->siglock provides a memory barrier.
314 *
315 * do_exit:
316 * The caller holds mm->mmap_sem. This means that the task which
317 * uses this mm can't pass exit_mm(), so it can't exit or clear
318 * its ->mm.
319 *
320 * de_thread:
321 * It does list_replace_rcu(&leader->tasks, &current->tasks),
322 * we must see either old or new leader, this does not matter.
323 * However, it can change p->sighand, so lock_task_sighand(p)
324 * must be used. Since p->mm != NULL and we hold ->mmap_sem
325 * it can't fail.
326 *
327 * Note also that "g" can be the old leader with ->mm == NULL
328 * and already unhashed and thus removed from ->thread_group.
329 * This is OK, __unhash_process()->list_del_rcu() does not
330 * clear the ->next pointer, we will find the new leader via
331 * next_thread().
332 */
333 rcu_read_lock();
334 for_each_process(g) {
335 if (g == tsk->group_leader)
336 continue;
337 if (g->flags & PF_KTHREAD)
338 continue;
339 p = g;
340 do {
341 if (p->mm) {
342 if (unlikely(p->mm == mm)) {
343 lock_task_sighand(p, &flags);
344 nr += zap_process(p, exit_code);
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700345 p->signal->flags = SIGNAL_GROUP_EXIT;
Alex Kelly10c28d92012-09-26 21:52:08 -0400346 unlock_task_sighand(p, &flags);
347 }
348 break;
349 }
350 } while_each_thread(g, p);
351 }
352 rcu_read_unlock();
353done:
354 atomic_set(&core_state->nr_threads, nr);
355 return nr;
356}
357
358static int coredump_wait(int exit_code, struct core_state *core_state)
359{
360 struct task_struct *tsk = current;
361 struct mm_struct *mm = tsk->mm;
362 int core_waiters = -EBUSY;
363
364 init_completion(&core_state->startup);
365 core_state->dumper.task = tsk;
366 core_state->dumper.next = NULL;
367
368 down_write(&mm->mmap_sem);
369 if (!mm->core_state)
370 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
371 up_write(&mm->mmap_sem);
372
373 if (core_waiters > 0) {
374 struct core_thread *ptr;
375
376 wait_for_completion(&core_state->startup);
377 /*
378 * Wait for all the threads to become inactive, so that
379 * all the thread context (extended register state, like
380 * fpu etc) gets copied to the memory.
381 */
382 ptr = core_state->dumper.next;
383 while (ptr != NULL) {
384 wait_task_inactive(ptr->task, 0);
385 ptr = ptr->next;
386 }
387 }
388
389 return core_waiters;
390}
391
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700392static void coredump_finish(struct mm_struct *mm, bool core_dumped)
Alex Kelly10c28d92012-09-26 21:52:08 -0400393{
394 struct core_thread *curr, *next;
395 struct task_struct *task;
396
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700397 spin_lock_irq(&current->sighand->siglock);
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700398 if (core_dumped && !__fatal_signal_pending(current))
399 current->signal->group_exit_code |= 0x80;
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700400 current->signal->group_exit_task = NULL;
401 current->signal->flags = SIGNAL_GROUP_EXIT;
402 spin_unlock_irq(&current->sighand->siglock);
403
Alex Kelly10c28d92012-09-26 21:52:08 -0400404 next = mm->core_state->dumper.next;
405 while ((curr = next) != NULL) {
406 next = curr->next;
407 task = curr->task;
408 /*
409 * see exit_mm(), curr->task must not see
410 * ->task == NULL before we read ->next.
411 */
412 smp_mb();
413 curr->task = NULL;
414 wake_up_process(task);
415 }
416
417 mm->core_state = NULL;
418}
419
Oleg Nesterov528f8272013-04-30 15:28:15 -0700420static bool dump_interrupted(void)
421{
422 /*
423 * SIGKILL or freezing() interrupt the coredumping. Perhaps we
424 * can do try_to_freeze() and check __fatal_signal_pending(),
425 * but then we need to teach dump_write() to restart and clear
426 * TIF_SIGPENDING.
427 */
428 return signal_pending(current);
429}
430
Alex Kelly10c28d92012-09-26 21:52:08 -0400431static void wait_for_dump_helpers(struct file *file)
432{
Al Virode32ec42013-03-21 11:16:56 -0400433 struct pipe_inode_info *pipe = file->private_data;
Alex Kelly10c28d92012-09-26 21:52:08 -0400434
435 pipe_lock(pipe);
436 pipe->readers++;
437 pipe->writers--;
Oleg Nesterovdc7ee2a2013-04-30 15:28:17 -0700438 wake_up_interruptible_sync(&pipe->wait);
439 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
440 pipe_unlock(pipe);
Alex Kelly10c28d92012-09-26 21:52:08 -0400441
Oleg Nesterovdc7ee2a2013-04-30 15:28:17 -0700442 /*
443 * We actually want wait_event_freezable() but then we need
444 * to clear TIF_SIGPENDING and improve dump_interrupted().
445 */
446 wait_event_interruptible(pipe->wait, pipe->readers == 1);
Alex Kelly10c28d92012-09-26 21:52:08 -0400447
Oleg Nesterovdc7ee2a2013-04-30 15:28:17 -0700448 pipe_lock(pipe);
Alex Kelly10c28d92012-09-26 21:52:08 -0400449 pipe->readers--;
450 pipe->writers++;
451 pipe_unlock(pipe);
Alex Kelly10c28d92012-09-26 21:52:08 -0400452}
453
454/*
455 * umh_pipe_setup
456 * helper function to customize the process used
457 * to collect the core in userspace. Specifically
458 * it sets up a pipe and installs it as fd 0 (stdin)
459 * for the process. Returns 0 on success, or
460 * PTR_ERR on failure.
461 * Note that it also sets the core limit to 1. This
462 * is a special value that we use to trap recursive
463 * core dumps
464 */
465static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
466{
467 struct file *files[2];
468 struct coredump_params *cp = (struct coredump_params *)info->data;
469 int err = create_pipe_files(files, 0);
470 if (err)
471 return err;
472
473 cp->file = files[1];
474
Al Viro45525b22012-10-16 13:30:07 -0400475 err = replace_fd(0, files[0], 0);
476 fput(files[0]);
Alex Kelly10c28d92012-09-26 21:52:08 -0400477 /* and disallow core files too */
478 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
479
Al Viro45525b22012-10-16 13:30:07 -0400480 return err;
Alex Kelly10c28d92012-09-26 21:52:08 -0400481}
482
Al Viro541880d2012-11-05 13:11:26 -0500483void do_coredump(siginfo_t *siginfo)
Alex Kelly10c28d92012-09-26 21:52:08 -0400484{
485 struct core_state core_state;
486 struct core_name cn;
487 struct mm_struct *mm = current->mm;
488 struct linux_binfmt * binfmt;
489 const struct cred *old_cred;
490 struct cred *cred;
491 int retval = 0;
492 int flag = 0;
493 int ispipe;
494 struct files_struct *displaced;
495 bool need_nonrelative = false;
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700496 bool core_dumped = false;
Alex Kelly10c28d92012-09-26 21:52:08 -0400497 static atomic_t core_dump_count = ATOMIC_INIT(0);
498 struct coredump_params cprm = {
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700499 .siginfo = siginfo,
Al Viro541880d2012-11-05 13:11:26 -0500500 .regs = signal_pt_regs(),
Alex Kelly10c28d92012-09-26 21:52:08 -0400501 .limit = rlimit(RLIMIT_CORE),
502 /*
503 * We must use the same mm->flags while dumping core to avoid
504 * inconsistency of bit flags, since this flag is not protected
505 * by any locks.
506 */
507 .mm_flags = mm->flags,
508 };
509
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700510 audit_core_dumps(siginfo->si_signo);
Alex Kelly10c28d92012-09-26 21:52:08 -0400511
512 binfmt = mm->binfmt;
513 if (!binfmt || !binfmt->core_dump)
514 goto fail;
515 if (!__get_dumpable(cprm.mm_flags))
516 goto fail;
517
518 cred = prepare_creds();
519 if (!cred)
520 goto fail;
521 /*
522 * We cannot trust fsuid as being the "true" uid of the process
523 * nor do we know its entire history. We only know it was tainted
524 * so we dump it as root in mode 2, and only into a controlled
525 * environment (pipe handler or fully qualified path).
526 */
Kees Cooke579d2c2013-02-27 17:03:15 -0800527 if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
Alex Kelly10c28d92012-09-26 21:52:08 -0400528 /* Setuid core dump mode */
529 flag = O_EXCL; /* Stop rewrite attacks */
530 cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */
531 need_nonrelative = true;
532 }
533
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700534 retval = coredump_wait(siginfo->si_signo, &core_state);
Alex Kelly10c28d92012-09-26 21:52:08 -0400535 if (retval < 0)
536 goto fail_creds;
537
538 old_cred = override_creds(cred);
539
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700540 ispipe = format_corename(&cn, &cprm);
Alex Kelly10c28d92012-09-26 21:52:08 -0400541
Lucas De Marchifb96c472013-04-30 15:28:06 -0700542 if (ispipe) {
Alex Kelly10c28d92012-09-26 21:52:08 -0400543 int dump_count;
544 char **helper_argv;
Lucas De Marchi907ed132013-04-30 15:28:07 -0700545 struct subprocess_info *sub_info;
Alex Kelly10c28d92012-09-26 21:52:08 -0400546
547 if (ispipe < 0) {
548 printk(KERN_WARNING "format_corename failed\n");
549 printk(KERN_WARNING "Aborting core\n");
Oleg Nesterove7fd1542013-07-03 15:08:16 -0700550 goto fail_unlock;
Alex Kelly10c28d92012-09-26 21:52:08 -0400551 }
552
553 if (cprm.limit == 1) {
554 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
555 *
556 * Normally core limits are irrelevant to pipes, since
557 * we're not writing to the file system, but we use
558 * cprm.limit of 1 here as a speacial value, this is a
559 * consistent way to catch recursive crashes.
560 * We can still crash if the core_pattern binary sets
561 * RLIM_CORE = !1, but it runs as root, and can do
562 * lots of stupid things.
563 *
564 * Note that we use task_tgid_vnr here to grab the pid
565 * of the process group leader. That way we get the
566 * right pid if a thread in a multi-threaded
567 * core_pattern process dies.
568 */
569 printk(KERN_WARNING
570 "Process %d(%s) has RLIMIT_CORE set to 1\n",
571 task_tgid_vnr(current), current->comm);
572 printk(KERN_WARNING "Aborting core\n");
573 goto fail_unlock;
574 }
575 cprm.limit = RLIM_INFINITY;
576
577 dump_count = atomic_inc_return(&core_dump_count);
578 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
579 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
580 task_tgid_vnr(current), current->comm);
581 printk(KERN_WARNING "Skipping core dump\n");
582 goto fail_dropcount;
583 }
584
Oleg Nesterov888ffc52013-07-03 15:08:23 -0700585 helper_argv = argv_split(GFP_KERNEL, cn.corename, NULL);
Alex Kelly10c28d92012-09-26 21:52:08 -0400586 if (!helper_argv) {
587 printk(KERN_WARNING "%s failed to allocate memory\n",
588 __func__);
589 goto fail_dropcount;
590 }
591
Lucas De Marchi907ed132013-04-30 15:28:07 -0700592 retval = -ENOMEM;
593 sub_info = call_usermodehelper_setup(helper_argv[0],
594 helper_argv, NULL, GFP_KERNEL,
595 umh_pipe_setup, NULL, &cprm);
596 if (sub_info)
597 retval = call_usermodehelper_exec(sub_info,
598 UMH_WAIT_EXEC);
599
Alex Kelly10c28d92012-09-26 21:52:08 -0400600 argv_free(helper_argv);
601 if (retval) {
Oleg Nesterov888ffc52013-07-03 15:08:23 -0700602 printk(KERN_INFO "Core dump to |%s pipe failed\n",
Alex Kelly10c28d92012-09-26 21:52:08 -0400603 cn.corename);
604 goto close_fail;
Lucas De Marchifb96c472013-04-30 15:28:06 -0700605 }
Alex Kelly10c28d92012-09-26 21:52:08 -0400606 } else {
607 struct inode *inode;
608
609 if (cprm.limit < binfmt->min_coredump)
610 goto fail_unlock;
611
612 if (need_nonrelative && cn.corename[0] != '/') {
613 printk(KERN_WARNING "Pid %d(%s) can only dump core "\
614 "to fully qualified path!\n",
615 task_tgid_vnr(current), current->comm);
616 printk(KERN_WARNING "Skipping core dump\n");
617 goto fail_unlock;
618 }
619
620 cprm.file = filp_open(cn.corename,
621 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
622 0600);
623 if (IS_ERR(cprm.file))
624 goto fail_unlock;
625
Al Viro496ad9a2013-01-23 17:07:38 -0500626 inode = file_inode(cprm.file);
Alex Kelly10c28d92012-09-26 21:52:08 -0400627 if (inode->i_nlink > 1)
628 goto close_fail;
629 if (d_unhashed(cprm.file->f_path.dentry))
630 goto close_fail;
631 /*
632 * AK: actually i see no reason to not allow this for named
633 * pipes etc, but keep the previous behaviour for now.
634 */
635 if (!S_ISREG(inode->i_mode))
636 goto close_fail;
637 /*
638 * Dont allow local users get cute and trick others to coredump
639 * into their pre-created files.
640 */
641 if (!uid_eq(inode->i_uid, current_fsuid()))
642 goto close_fail;
643 if (!cprm.file->f_op || !cprm.file->f_op->write)
644 goto close_fail;
645 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
646 goto close_fail;
647 }
648
649 /* get us an unshared descriptor table; almost always a no-op */
650 retval = unshare_files(&displaced);
651 if (retval)
652 goto close_fail;
653 if (displaced)
654 put_files_struct(displaced);
Al Viroe86d35c2013-05-04 14:45:54 -0400655 if (!dump_interrupted()) {
656 file_start_write(cprm.file);
657 core_dumped = binfmt->core_dump(&cprm);
658 file_end_write(cprm.file);
659 }
Alex Kelly10c28d92012-09-26 21:52:08 -0400660 if (ispipe && core_pipe_limit)
661 wait_for_dump_helpers(cprm.file);
662close_fail:
663 if (cprm.file)
664 filp_close(cprm.file, NULL);
665fail_dropcount:
666 if (ispipe)
667 atomic_dec(&core_dump_count);
668fail_unlock:
669 kfree(cn.corename);
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700670 coredump_finish(mm, core_dumped);
Alex Kelly10c28d92012-09-26 21:52:08 -0400671 revert_creds(old_cred);
672fail_creds:
673 put_cred(cred);
674fail:
675 return;
676}
677
678/*
679 * Core dumping helper functions. These are the only things you should
680 * do on a core-file: use only these functions to write out all the
681 * necessary info.
682 */
683int dump_write(struct file *file, const void *addr, int nr)
684{
Oleg Nesterov528f8272013-04-30 15:28:15 -0700685 return !dump_interrupted() &&
686 access_ok(VERIFY_READ, addr, nr) &&
687 file->f_op->write(file, addr, nr, &file->f_pos) == nr;
Alex Kelly10c28d92012-09-26 21:52:08 -0400688}
689EXPORT_SYMBOL(dump_write);
690
691int dump_seek(struct file *file, loff_t off)
692{
693 int ret = 1;
694
695 if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
Oleg Nesterov528f8272013-04-30 15:28:15 -0700696 if (dump_interrupted() ||
697 file->f_op->llseek(file, off, SEEK_CUR) < 0)
Alex Kelly10c28d92012-09-26 21:52:08 -0400698 return 0;
699 } else {
700 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
701
702 if (!buf)
703 return 0;
704 while (off > 0) {
705 unsigned long n = off;
706
707 if (n > PAGE_SIZE)
708 n = PAGE_SIZE;
709 if (!dump_write(file, buf, n)) {
710 ret = 0;
711 break;
712 }
713 off -= n;
714 }
715 free_page((unsigned long)buf);
716 }
717 return ret;
718}
719EXPORT_SYMBOL(dump_seek);