blob: 11bc368e00176fa17a722a0affe86a68dd07b372 [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;
48char core_pattern[CORENAME_MAX_SIZE] = "core";
49unsigned int core_pipe_limit;
50
51struct core_name {
52 char *corename;
53 int used, size;
54};
55static atomic_t call_count = ATOMIC_INIT(1);
56
57/* The maximal length of core_pattern is also specified in sysctl.c */
58
59static int expand_corename(struct core_name *cn)
60{
Oleg Nesterove7fd1542013-07-03 15:08:16 -070061 int size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
62 char *corename = krealloc(cn->corename, size, GFP_KERNEL);
Alex Kelly10c28d92012-09-26 21:52:08 -040063
Oleg Nesterove7fd1542013-07-03 15:08:16 -070064 if (!corename)
Alex Kelly10c28d92012-09-26 21:52:08 -040065 return -ENOMEM;
Alex Kelly10c28d92012-09-26 21:52:08 -040066
Oleg Nesterove7fd1542013-07-03 15:08:16 -070067 cn->size = size;
68 cn->corename = corename;
Alex Kelly10c28d92012-09-26 21:52:08 -040069 return 0;
70}
71
72static int cn_printf(struct core_name *cn, const char *fmt, ...)
73{
74 char *cur;
75 int need;
76 int ret;
77 va_list arg;
78
79 va_start(arg, fmt);
80 need = vsnprintf(NULL, 0, fmt, arg);
81 va_end(arg);
82
83 if (likely(need < cn->size - cn->used - 1))
84 goto out_printf;
85
86 ret = expand_corename(cn);
87 if (ret)
88 goto expand_fail;
89
90out_printf:
91 cur = cn->corename + cn->used;
92 va_start(arg, fmt);
93 vsnprintf(cur, need + 1, fmt, arg);
94 va_end(arg);
95 cn->used += need;
96 return 0;
97
98expand_fail:
99 return ret;
100}
101
102static void cn_escape(char *str)
103{
104 for (; *str; str++)
105 if (*str == '/')
106 *str = '!';
107}
108
109static int cn_print_exe_file(struct core_name *cn)
110{
111 struct file *exe_file;
112 char *pathbuf, *path;
113 int ret;
114
115 exe_file = get_mm_exe_file(current->mm);
116 if (!exe_file) {
117 char *commstart = cn->corename + cn->used;
118 ret = cn_printf(cn, "%s (path unknown)", current->comm);
119 cn_escape(commstart);
120 return ret;
121 }
122
123 pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
124 if (!pathbuf) {
125 ret = -ENOMEM;
126 goto put_exe_file;
127 }
128
129 path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
130 if (IS_ERR(path)) {
131 ret = PTR_ERR(path);
132 goto free_buf;
133 }
134
135 cn_escape(path);
136
137 ret = cn_printf(cn, "%s", path);
138
139free_buf:
140 kfree(pathbuf);
141put_exe_file:
142 fput(exe_file);
143 return ret;
144}
145
146/* format_corename will inspect the pattern parameter, and output a
147 * name into corename, which must have space for at least
148 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
149 */
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700150static int format_corename(struct core_name *cn, struct coredump_params *cprm)
Alex Kelly10c28d92012-09-26 21:52:08 -0400151{
152 const struct cred *cred = current_cred();
153 const char *pat_ptr = core_pattern;
154 int ispipe = (*pat_ptr == '|');
155 int pid_in_pattern = 0;
156 int err = 0;
157
Oleg Nesterove7fd1542013-07-03 15:08:16 -0700158 cn->used = 0;
Alex Kelly10c28d92012-09-26 21:52:08 -0400159 cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
160 cn->corename = kmalloc(cn->size, GFP_KERNEL);
Alex Kelly10c28d92012-09-26 21:52:08 -0400161 if (!cn->corename)
162 return -ENOMEM;
163
164 /* Repeat as long as we have more pattern to process and more output
165 space */
166 while (*pat_ptr) {
167 if (*pat_ptr != '%') {
168 if (*pat_ptr == 0)
169 goto out;
170 err = cn_printf(cn, "%c", *pat_ptr++);
171 } else {
172 switch (*++pat_ptr) {
173 /* single % at the end, drop that */
174 case 0:
175 goto out;
176 /* Double percent, output one percent */
177 case '%':
178 err = cn_printf(cn, "%c", '%');
179 break;
180 /* pid */
181 case 'p':
182 pid_in_pattern = 1;
183 err = cn_printf(cn, "%d",
184 task_tgid_vnr(current));
185 break;
186 /* uid */
187 case 'u':
188 err = cn_printf(cn, "%d", cred->uid);
189 break;
190 /* gid */
191 case 'g':
192 err = cn_printf(cn, "%d", cred->gid);
193 break;
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700194 case 'd':
195 err = cn_printf(cn, "%d",
196 __get_dumpable(cprm->mm_flags));
197 break;
Alex Kelly10c28d92012-09-26 21:52:08 -0400198 /* signal that caused the coredump */
199 case 's':
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700200 err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
Alex Kelly10c28d92012-09-26 21:52:08 -0400201 break;
202 /* UNIX time of coredump */
203 case 't': {
204 struct timeval tv;
205 do_gettimeofday(&tv);
206 err = cn_printf(cn, "%lu", tv.tv_sec);
207 break;
208 }
209 /* hostname */
210 case 'h': {
211 char *namestart = cn->corename + cn->used;
212 down_read(&uts_sem);
213 err = cn_printf(cn, "%s",
214 utsname()->nodename);
215 up_read(&uts_sem);
216 cn_escape(namestart);
217 break;
218 }
219 /* executable */
220 case 'e': {
221 char *commstart = cn->corename + cn->used;
222 err = cn_printf(cn, "%s", current->comm);
223 cn_escape(commstart);
224 break;
225 }
226 case 'E':
227 err = cn_print_exe_file(cn);
228 break;
229 /* core limit size */
230 case 'c':
231 err = cn_printf(cn, "%lu",
232 rlimit(RLIMIT_CORE));
233 break;
234 default:
235 break;
236 }
237 ++pat_ptr;
238 }
239
240 if (err)
241 return err;
242 }
243
244 /* Backward compatibility with core_uses_pid:
245 *
246 * If core_pattern does not include a %p (as is the default)
247 * and core_uses_pid is set, then .%pid will be appended to
248 * the filename. Do not do this for piped commands. */
249 if (!ispipe && !pid_in_pattern && core_uses_pid) {
250 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
251 if (err)
252 return err;
253 }
254out:
255 return ispipe;
256}
257
258static int zap_process(struct task_struct *start, int exit_code)
259{
260 struct task_struct *t;
261 int nr = 0;
262
Alex Kelly10c28d92012-09-26 21:52:08 -0400263 start->signal->group_exit_code = exit_code;
264 start->signal->group_stop_count = 0;
265
266 t = start;
267 do {
268 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
269 if (t != current && t->mm) {
270 sigaddset(&t->pending.signal, SIGKILL);
271 signal_wake_up(t, 1);
272 nr++;
273 }
274 } while_each_thread(start, t);
275
276 return nr;
277}
278
Oleg Nesterov403bad72013-04-30 15:28:10 -0700279static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
280 struct core_state *core_state, int exit_code)
Alex Kelly10c28d92012-09-26 21:52:08 -0400281{
282 struct task_struct *g, *p;
283 unsigned long flags;
284 int nr = -EAGAIN;
285
286 spin_lock_irq(&tsk->sighand->siglock);
287 if (!signal_group_exit(tsk->signal)) {
288 mm->core_state = core_state;
289 nr = zap_process(tsk, exit_code);
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700290 tsk->signal->group_exit_task = tsk;
Oleg Nesterov403bad72013-04-30 15:28:10 -0700291 /* ignore all signals except SIGKILL, see prepare_signal() */
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700292 tsk->signal->flags = SIGNAL_GROUP_COREDUMP;
Oleg Nesterov403bad72013-04-30 15:28:10 -0700293 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
Alex Kelly10c28d92012-09-26 21:52:08 -0400294 }
295 spin_unlock_irq(&tsk->sighand->siglock);
296 if (unlikely(nr < 0))
297 return nr;
298
Oleg Nesterov079148b2013-04-30 15:28:16 -0700299 tsk->flags = PF_DUMPCORE;
Alex Kelly10c28d92012-09-26 21:52:08 -0400300 if (atomic_read(&mm->mm_users) == nr + 1)
301 goto done;
302 /*
303 * We should find and kill all tasks which use this mm, and we should
304 * count them correctly into ->nr_threads. We don't take tasklist
305 * lock, but this is safe wrt:
306 *
307 * fork:
308 * None of sub-threads can fork after zap_process(leader). All
309 * processes which were created before this point should be
310 * visible to zap_threads() because copy_process() adds the new
311 * process to the tail of init_task.tasks list, and lock/unlock
312 * of ->siglock provides a memory barrier.
313 *
314 * do_exit:
315 * The caller holds mm->mmap_sem. This means that the task which
316 * uses this mm can't pass exit_mm(), so it can't exit or clear
317 * its ->mm.
318 *
319 * de_thread:
320 * It does list_replace_rcu(&leader->tasks, &current->tasks),
321 * we must see either old or new leader, this does not matter.
322 * However, it can change p->sighand, so lock_task_sighand(p)
323 * must be used. Since p->mm != NULL and we hold ->mmap_sem
324 * it can't fail.
325 *
326 * Note also that "g" can be the old leader with ->mm == NULL
327 * and already unhashed and thus removed from ->thread_group.
328 * This is OK, __unhash_process()->list_del_rcu() does not
329 * clear the ->next pointer, we will find the new leader via
330 * next_thread().
331 */
332 rcu_read_lock();
333 for_each_process(g) {
334 if (g == tsk->group_leader)
335 continue;
336 if (g->flags & PF_KTHREAD)
337 continue;
338 p = g;
339 do {
340 if (p->mm) {
341 if (unlikely(p->mm == mm)) {
342 lock_task_sighand(p, &flags);
343 nr += zap_process(p, exit_code);
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700344 p->signal->flags = SIGNAL_GROUP_EXIT;
Alex Kelly10c28d92012-09-26 21:52:08 -0400345 unlock_task_sighand(p, &flags);
346 }
347 break;
348 }
349 } while_each_thread(g, p);
350 }
351 rcu_read_unlock();
352done:
353 atomic_set(&core_state->nr_threads, nr);
354 return nr;
355}
356
357static int coredump_wait(int exit_code, struct core_state *core_state)
358{
359 struct task_struct *tsk = current;
360 struct mm_struct *mm = tsk->mm;
361 int core_waiters = -EBUSY;
362
363 init_completion(&core_state->startup);
364 core_state->dumper.task = tsk;
365 core_state->dumper.next = NULL;
366
367 down_write(&mm->mmap_sem);
368 if (!mm->core_state)
369 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
370 up_write(&mm->mmap_sem);
371
372 if (core_waiters > 0) {
373 struct core_thread *ptr;
374
375 wait_for_completion(&core_state->startup);
376 /*
377 * Wait for all the threads to become inactive, so that
378 * all the thread context (extended register state, like
379 * fpu etc) gets copied to the memory.
380 */
381 ptr = core_state->dumper.next;
382 while (ptr != NULL) {
383 wait_task_inactive(ptr->task, 0);
384 ptr = ptr->next;
385 }
386 }
387
388 return core_waiters;
389}
390
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700391static void coredump_finish(struct mm_struct *mm, bool core_dumped)
Alex Kelly10c28d92012-09-26 21:52:08 -0400392{
393 struct core_thread *curr, *next;
394 struct task_struct *task;
395
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700396 spin_lock_irq(&current->sighand->siglock);
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700397 if (core_dumped && !__fatal_signal_pending(current))
398 current->signal->group_exit_code |= 0x80;
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700399 current->signal->group_exit_task = NULL;
400 current->signal->flags = SIGNAL_GROUP_EXIT;
401 spin_unlock_irq(&current->sighand->siglock);
402
Alex Kelly10c28d92012-09-26 21:52:08 -0400403 next = mm->core_state->dumper.next;
404 while ((curr = next) != NULL) {
405 next = curr->next;
406 task = curr->task;
407 /*
408 * see exit_mm(), curr->task must not see
409 * ->task == NULL before we read ->next.
410 */
411 smp_mb();
412 curr->task = NULL;
413 wake_up_process(task);
414 }
415
416 mm->core_state = NULL;
417}
418
Oleg Nesterov528f8272013-04-30 15:28:15 -0700419static bool dump_interrupted(void)
420{
421 /*
422 * SIGKILL or freezing() interrupt the coredumping. Perhaps we
423 * can do try_to_freeze() and check __fatal_signal_pending(),
424 * but then we need to teach dump_write() to restart and clear
425 * TIF_SIGPENDING.
426 */
427 return signal_pending(current);
428}
429
Alex Kelly10c28d92012-09-26 21:52:08 -0400430static void wait_for_dump_helpers(struct file *file)
431{
Al Virode32ec42013-03-21 11:16:56 -0400432 struct pipe_inode_info *pipe = file->private_data;
Alex Kelly10c28d92012-09-26 21:52:08 -0400433
434 pipe_lock(pipe);
435 pipe->readers++;
436 pipe->writers--;
Oleg Nesterovdc7ee2a2013-04-30 15:28:17 -0700437 wake_up_interruptible_sync(&pipe->wait);
438 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
439 pipe_unlock(pipe);
Alex Kelly10c28d92012-09-26 21:52:08 -0400440
Oleg Nesterovdc7ee2a2013-04-30 15:28:17 -0700441 /*
442 * We actually want wait_event_freezable() but then we need
443 * to clear TIF_SIGPENDING and improve dump_interrupted().
444 */
445 wait_event_interruptible(pipe->wait, pipe->readers == 1);
Alex Kelly10c28d92012-09-26 21:52:08 -0400446
Oleg Nesterovdc7ee2a2013-04-30 15:28:17 -0700447 pipe_lock(pipe);
Alex Kelly10c28d92012-09-26 21:52:08 -0400448 pipe->readers--;
449 pipe->writers++;
450 pipe_unlock(pipe);
Alex Kelly10c28d92012-09-26 21:52:08 -0400451}
452
453/*
454 * umh_pipe_setup
455 * helper function to customize the process used
456 * to collect the core in userspace. Specifically
457 * it sets up a pipe and installs it as fd 0 (stdin)
458 * for the process. Returns 0 on success, or
459 * PTR_ERR on failure.
460 * Note that it also sets the core limit to 1. This
461 * is a special value that we use to trap recursive
462 * core dumps
463 */
464static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
465{
466 struct file *files[2];
467 struct coredump_params *cp = (struct coredump_params *)info->data;
468 int err = create_pipe_files(files, 0);
469 if (err)
470 return err;
471
472 cp->file = files[1];
473
Al Viro45525b22012-10-16 13:30:07 -0400474 err = replace_fd(0, files[0], 0);
475 fput(files[0]);
Alex Kelly10c28d92012-09-26 21:52:08 -0400476 /* and disallow core files too */
477 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
478
Al Viro45525b22012-10-16 13:30:07 -0400479 return err;
Alex Kelly10c28d92012-09-26 21:52:08 -0400480}
481
Al Viro541880d2012-11-05 13:11:26 -0500482void do_coredump(siginfo_t *siginfo)
Alex Kelly10c28d92012-09-26 21:52:08 -0400483{
484 struct core_state core_state;
485 struct core_name cn;
486 struct mm_struct *mm = current->mm;
487 struct linux_binfmt * binfmt;
488 const struct cred *old_cred;
489 struct cred *cred;
490 int retval = 0;
491 int flag = 0;
492 int ispipe;
493 struct files_struct *displaced;
494 bool need_nonrelative = false;
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700495 bool core_dumped = false;
Alex Kelly10c28d92012-09-26 21:52:08 -0400496 static atomic_t core_dump_count = ATOMIC_INIT(0);
497 struct coredump_params cprm = {
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700498 .siginfo = siginfo,
Al Viro541880d2012-11-05 13:11:26 -0500499 .regs = signal_pt_regs(),
Alex Kelly10c28d92012-09-26 21:52:08 -0400500 .limit = rlimit(RLIMIT_CORE),
501 /*
502 * We must use the same mm->flags while dumping core to avoid
503 * inconsistency of bit flags, since this flag is not protected
504 * by any locks.
505 */
506 .mm_flags = mm->flags,
507 };
508
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700509 audit_core_dumps(siginfo->si_signo);
Alex Kelly10c28d92012-09-26 21:52:08 -0400510
511 binfmt = mm->binfmt;
512 if (!binfmt || !binfmt->core_dump)
513 goto fail;
514 if (!__get_dumpable(cprm.mm_flags))
515 goto fail;
516
517 cred = prepare_creds();
518 if (!cred)
519 goto fail;
520 /*
521 * We cannot trust fsuid as being the "true" uid of the process
522 * nor do we know its entire history. We only know it was tainted
523 * so we dump it as root in mode 2, and only into a controlled
524 * environment (pipe handler or fully qualified path).
525 */
Kees Cooke579d2c2013-02-27 17:03:15 -0800526 if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
Alex Kelly10c28d92012-09-26 21:52:08 -0400527 /* Setuid core dump mode */
528 flag = O_EXCL; /* Stop rewrite attacks */
529 cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */
530 need_nonrelative = true;
531 }
532
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700533 retval = coredump_wait(siginfo->si_signo, &core_state);
Alex Kelly10c28d92012-09-26 21:52:08 -0400534 if (retval < 0)
535 goto fail_creds;
536
537 old_cred = override_creds(cred);
538
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700539 ispipe = format_corename(&cn, &cprm);
Alex Kelly10c28d92012-09-26 21:52:08 -0400540
Lucas De Marchifb96c472013-04-30 15:28:06 -0700541 if (ispipe) {
Alex Kelly10c28d92012-09-26 21:52:08 -0400542 int dump_count;
543 char **helper_argv;
Lucas De Marchi907ed132013-04-30 15:28:07 -0700544 struct subprocess_info *sub_info;
Alex Kelly10c28d92012-09-26 21:52:08 -0400545
546 if (ispipe < 0) {
547 printk(KERN_WARNING "format_corename failed\n");
548 printk(KERN_WARNING "Aborting core\n");
Oleg Nesterove7fd1542013-07-03 15:08:16 -0700549 goto fail_unlock;
Alex Kelly10c28d92012-09-26 21:52:08 -0400550 }
551
552 if (cprm.limit == 1) {
553 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
554 *
555 * Normally core limits are irrelevant to pipes, since
556 * we're not writing to the file system, but we use
557 * cprm.limit of 1 here as a speacial value, this is a
558 * consistent way to catch recursive crashes.
559 * We can still crash if the core_pattern binary sets
560 * RLIM_CORE = !1, but it runs as root, and can do
561 * lots of stupid things.
562 *
563 * Note that we use task_tgid_vnr here to grab the pid
564 * of the process group leader. That way we get the
565 * right pid if a thread in a multi-threaded
566 * core_pattern process dies.
567 */
568 printk(KERN_WARNING
569 "Process %d(%s) has RLIMIT_CORE set to 1\n",
570 task_tgid_vnr(current), current->comm);
571 printk(KERN_WARNING "Aborting core\n");
572 goto fail_unlock;
573 }
574 cprm.limit = RLIM_INFINITY;
575
576 dump_count = atomic_inc_return(&core_dump_count);
577 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
578 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
579 task_tgid_vnr(current), current->comm);
580 printk(KERN_WARNING "Skipping core dump\n");
581 goto fail_dropcount;
582 }
583
584 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
585 if (!helper_argv) {
586 printk(KERN_WARNING "%s failed to allocate memory\n",
587 __func__);
588 goto fail_dropcount;
589 }
590
Lucas De Marchi907ed132013-04-30 15:28:07 -0700591 retval = -ENOMEM;
592 sub_info = call_usermodehelper_setup(helper_argv[0],
593 helper_argv, NULL, GFP_KERNEL,
594 umh_pipe_setup, NULL, &cprm);
595 if (sub_info)
596 retval = call_usermodehelper_exec(sub_info,
597 UMH_WAIT_EXEC);
598
Alex Kelly10c28d92012-09-26 21:52:08 -0400599 argv_free(helper_argv);
600 if (retval) {
Lucas De Marchifb96c472013-04-30 15:28:06 -0700601 printk(KERN_INFO "Core dump to %s pipe failed\n",
Alex Kelly10c28d92012-09-26 21:52:08 -0400602 cn.corename);
603 goto close_fail;
Lucas De Marchifb96c472013-04-30 15:28:06 -0700604 }
Alex Kelly10c28d92012-09-26 21:52:08 -0400605 } else {
606 struct inode *inode;
607
608 if (cprm.limit < binfmt->min_coredump)
609 goto fail_unlock;
610
611 if (need_nonrelative && cn.corename[0] != '/') {
612 printk(KERN_WARNING "Pid %d(%s) can only dump core "\
613 "to fully qualified path!\n",
614 task_tgid_vnr(current), current->comm);
615 printk(KERN_WARNING "Skipping core dump\n");
616 goto fail_unlock;
617 }
618
619 cprm.file = filp_open(cn.corename,
620 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
621 0600);
622 if (IS_ERR(cprm.file))
623 goto fail_unlock;
624
Al Viro496ad9a2013-01-23 17:07:38 -0500625 inode = file_inode(cprm.file);
Alex Kelly10c28d92012-09-26 21:52:08 -0400626 if (inode->i_nlink > 1)
627 goto close_fail;
628 if (d_unhashed(cprm.file->f_path.dentry))
629 goto close_fail;
630 /*
631 * AK: actually i see no reason to not allow this for named
632 * pipes etc, but keep the previous behaviour for now.
633 */
634 if (!S_ISREG(inode->i_mode))
635 goto close_fail;
636 /*
637 * Dont allow local users get cute and trick others to coredump
638 * into their pre-created files.
639 */
640 if (!uid_eq(inode->i_uid, current_fsuid()))
641 goto close_fail;
642 if (!cprm.file->f_op || !cprm.file->f_op->write)
643 goto close_fail;
644 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
645 goto close_fail;
646 }
647
648 /* get us an unshared descriptor table; almost always a no-op */
649 retval = unshare_files(&displaced);
650 if (retval)
651 goto close_fail;
652 if (displaced)
653 put_files_struct(displaced);
Al Viroe86d35c2013-05-04 14:45:54 -0400654 if (!dump_interrupted()) {
655 file_start_write(cprm.file);
656 core_dumped = binfmt->core_dump(&cprm);
657 file_end_write(cprm.file);
658 }
Alex Kelly10c28d92012-09-26 21:52:08 -0400659 if (ispipe && core_pipe_limit)
660 wait_for_dump_helpers(cprm.file);
661close_fail:
662 if (cprm.file)
663 filp_close(cprm.file, NULL);
664fail_dropcount:
665 if (ispipe)
666 atomic_dec(&core_dump_count);
667fail_unlock:
668 kfree(cn.corename);
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700669 coredump_finish(mm, core_dumped);
Alex Kelly10c28d92012-09-26 21:52:08 -0400670 revert_creds(old_cred);
671fail_creds:
672 put_cred(cred);
673fail:
674 return;
675}
676
677/*
678 * Core dumping helper functions. These are the only things you should
679 * do on a core-file: use only these functions to write out all the
680 * necessary info.
681 */
682int dump_write(struct file *file, const void *addr, int nr)
683{
Oleg Nesterov528f8272013-04-30 15:28:15 -0700684 return !dump_interrupted() &&
685 access_ok(VERIFY_READ, addr, nr) &&
686 file->f_op->write(file, addr, nr, &file->f_pos) == nr;
Alex Kelly10c28d92012-09-26 21:52:08 -0400687}
688EXPORT_SYMBOL(dump_write);
689
690int dump_seek(struct file *file, loff_t off)
691{
692 int ret = 1;
693
694 if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
Oleg Nesterov528f8272013-04-30 15:28:15 -0700695 if (dump_interrupted() ||
696 file->f_op->llseek(file, off, SEEK_CUR) < 0)
Alex Kelly10c28d92012-09-26 21:52:08 -0400697 return 0;
698 } else {
699 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
700
701 if (!buf)
702 return 0;
703 while (off > 0) {
704 unsigned long n = off;
705
706 if (n > PAGE_SIZE)
707 n = PAGE_SIZE;
708 if (!dump_write(file, buf, n)) {
709 ret = 0;
710 break;
711 }
712 off -= n;
713 }
714 free_page((unsigned long)buf);
715 }
716 return ret;
717}
718EXPORT_SYMBOL(dump_seek);