blob: dafafbafa7313e2e7ef46d05619482b2edf5645d [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{
61 char *old_corename = cn->corename;
62
63 cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
64 cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
65
66 if (!cn->corename) {
67 kfree(old_corename);
68 return -ENOMEM;
69 }
70
71 return 0;
72}
73
74static int cn_printf(struct core_name *cn, const char *fmt, ...)
75{
76 char *cur;
77 int need;
78 int ret;
79 va_list arg;
80
81 va_start(arg, fmt);
82 need = vsnprintf(NULL, 0, fmt, arg);
83 va_end(arg);
84
85 if (likely(need < cn->size - cn->used - 1))
86 goto out_printf;
87
88 ret = expand_corename(cn);
89 if (ret)
90 goto expand_fail;
91
92out_printf:
93 cur = cn->corename + cn->used;
94 va_start(arg, fmt);
95 vsnprintf(cur, need + 1, fmt, arg);
96 va_end(arg);
97 cn->used += need;
98 return 0;
99
100expand_fail:
101 return ret;
102}
103
104static void cn_escape(char *str)
105{
106 for (; *str; str++)
107 if (*str == '/')
108 *str = '!';
109}
110
111static int cn_print_exe_file(struct core_name *cn)
112{
113 struct file *exe_file;
114 char *pathbuf, *path;
115 int ret;
116
117 exe_file = get_mm_exe_file(current->mm);
118 if (!exe_file) {
119 char *commstart = cn->corename + cn->used;
120 ret = cn_printf(cn, "%s (path unknown)", current->comm);
121 cn_escape(commstart);
122 return ret;
123 }
124
125 pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
126 if (!pathbuf) {
127 ret = -ENOMEM;
128 goto put_exe_file;
129 }
130
131 path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
132 if (IS_ERR(path)) {
133 ret = PTR_ERR(path);
134 goto free_buf;
135 }
136
137 cn_escape(path);
138
139 ret = cn_printf(cn, "%s", path);
140
141free_buf:
142 kfree(pathbuf);
143put_exe_file:
144 fput(exe_file);
145 return ret;
146}
147
148/* format_corename will inspect the pattern parameter, and output a
149 * name into corename, which must have space for at least
150 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
151 */
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700152static int format_corename(struct core_name *cn, struct coredump_params *cprm)
Alex Kelly10c28d92012-09-26 21:52:08 -0400153{
154 const struct cred *cred = current_cred();
155 const char *pat_ptr = core_pattern;
156 int ispipe = (*pat_ptr == '|');
157 int pid_in_pattern = 0;
158 int err = 0;
159
160 cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
161 cn->corename = kmalloc(cn->size, GFP_KERNEL);
162 cn->used = 0;
163
164 if (!cn->corename)
165 return -ENOMEM;
166
167 /* Repeat as long as we have more pattern to process and more output
168 space */
169 while (*pat_ptr) {
170 if (*pat_ptr != '%') {
171 if (*pat_ptr == 0)
172 goto out;
173 err = cn_printf(cn, "%c", *pat_ptr++);
174 } else {
175 switch (*++pat_ptr) {
176 /* single % at the end, drop that */
177 case 0:
178 goto out;
179 /* Double percent, output one percent */
180 case '%':
181 err = cn_printf(cn, "%c", '%');
182 break;
183 /* pid */
184 case 'p':
185 pid_in_pattern = 1;
186 err = cn_printf(cn, "%d",
187 task_tgid_vnr(current));
188 break;
189 /* uid */
190 case 'u':
191 err = cn_printf(cn, "%d", cred->uid);
192 break;
193 /* gid */
194 case 'g':
195 err = cn_printf(cn, "%d", cred->gid);
196 break;
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700197 case 'd':
198 err = cn_printf(cn, "%d",
199 __get_dumpable(cprm->mm_flags));
200 break;
Alex Kelly10c28d92012-09-26 21:52:08 -0400201 /* signal that caused the coredump */
202 case 's':
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700203 err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
Alex Kelly10c28d92012-09-26 21:52:08 -0400204 break;
205 /* UNIX time of coredump */
206 case 't': {
207 struct timeval tv;
208 do_gettimeofday(&tv);
209 err = cn_printf(cn, "%lu", tv.tv_sec);
210 break;
211 }
212 /* hostname */
213 case 'h': {
214 char *namestart = cn->corename + cn->used;
215 down_read(&uts_sem);
216 err = cn_printf(cn, "%s",
217 utsname()->nodename);
218 up_read(&uts_sem);
219 cn_escape(namestart);
220 break;
221 }
222 /* executable */
223 case 'e': {
224 char *commstart = cn->corename + cn->used;
225 err = cn_printf(cn, "%s", current->comm);
226 cn_escape(commstart);
227 break;
228 }
229 case 'E':
230 err = cn_print_exe_file(cn);
231 break;
232 /* core limit size */
233 case 'c':
234 err = cn_printf(cn, "%lu",
235 rlimit(RLIMIT_CORE));
236 break;
237 default:
238 break;
239 }
240 ++pat_ptr;
241 }
242
243 if (err)
244 return err;
245 }
246
247 /* Backward compatibility with core_uses_pid:
248 *
249 * If core_pattern does not include a %p (as is the default)
250 * and core_uses_pid is set, then .%pid will be appended to
251 * the filename. Do not do this for piped commands. */
252 if (!ispipe && !pid_in_pattern && core_uses_pid) {
253 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
254 if (err)
255 return err;
256 }
257out:
258 return ispipe;
259}
260
261static int zap_process(struct task_struct *start, int exit_code)
262{
263 struct task_struct *t;
264 int nr = 0;
265
Alex Kelly10c28d92012-09-26 21:52:08 -0400266 start->signal->group_exit_code = exit_code;
267 start->signal->group_stop_count = 0;
268
269 t = start;
270 do {
271 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
272 if (t != current && t->mm) {
273 sigaddset(&t->pending.signal, SIGKILL);
274 signal_wake_up(t, 1);
275 nr++;
276 }
277 } while_each_thread(start, t);
278
279 return nr;
280}
281
Oleg Nesterov403bad72013-04-30 15:28:10 -0700282static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
283 struct core_state *core_state, int exit_code)
Alex Kelly10c28d92012-09-26 21:52:08 -0400284{
285 struct task_struct *g, *p;
286 unsigned long flags;
287 int nr = -EAGAIN;
288
289 spin_lock_irq(&tsk->sighand->siglock);
290 if (!signal_group_exit(tsk->signal)) {
291 mm->core_state = core_state;
292 nr = zap_process(tsk, exit_code);
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700293 tsk->signal->group_exit_task = tsk;
Oleg Nesterov403bad72013-04-30 15:28:10 -0700294 /* ignore all signals except SIGKILL, see prepare_signal() */
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700295 tsk->signal->flags = SIGNAL_GROUP_COREDUMP;
Oleg Nesterov403bad72013-04-30 15:28:10 -0700296 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
Alex Kelly10c28d92012-09-26 21:52:08 -0400297 }
298 spin_unlock_irq(&tsk->sighand->siglock);
299 if (unlikely(nr < 0))
300 return nr;
301
Oleg Nesterov079148b2013-04-30 15:28:16 -0700302 tsk->flags = PF_DUMPCORE;
Alex Kelly10c28d92012-09-26 21:52:08 -0400303 if (atomic_read(&mm->mm_users) == nr + 1)
304 goto done;
305 /*
306 * We should find and kill all tasks which use this mm, and we should
307 * count them correctly into ->nr_threads. We don't take tasklist
308 * lock, but this is safe wrt:
309 *
310 * fork:
311 * None of sub-threads can fork after zap_process(leader). All
312 * processes which were created before this point should be
313 * visible to zap_threads() because copy_process() adds the new
314 * process to the tail of init_task.tasks list, and lock/unlock
315 * of ->siglock provides a memory barrier.
316 *
317 * do_exit:
318 * The caller holds mm->mmap_sem. This means that the task which
319 * uses this mm can't pass exit_mm(), so it can't exit or clear
320 * its ->mm.
321 *
322 * de_thread:
323 * It does list_replace_rcu(&leader->tasks, &current->tasks),
324 * we must see either old or new leader, this does not matter.
325 * However, it can change p->sighand, so lock_task_sighand(p)
326 * must be used. Since p->mm != NULL and we hold ->mmap_sem
327 * it can't fail.
328 *
329 * Note also that "g" can be the old leader with ->mm == NULL
330 * and already unhashed and thus removed from ->thread_group.
331 * This is OK, __unhash_process()->list_del_rcu() does not
332 * clear the ->next pointer, we will find the new leader via
333 * next_thread().
334 */
335 rcu_read_lock();
336 for_each_process(g) {
337 if (g == tsk->group_leader)
338 continue;
339 if (g->flags & PF_KTHREAD)
340 continue;
341 p = g;
342 do {
343 if (p->mm) {
344 if (unlikely(p->mm == mm)) {
345 lock_task_sighand(p, &flags);
346 nr += zap_process(p, exit_code);
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700347 p->signal->flags = SIGNAL_GROUP_EXIT;
Alex Kelly10c28d92012-09-26 21:52:08 -0400348 unlock_task_sighand(p, &flags);
349 }
350 break;
351 }
352 } while_each_thread(g, p);
353 }
354 rcu_read_unlock();
355done:
356 atomic_set(&core_state->nr_threads, nr);
357 return nr;
358}
359
360static int coredump_wait(int exit_code, struct core_state *core_state)
361{
362 struct task_struct *tsk = current;
363 struct mm_struct *mm = tsk->mm;
364 int core_waiters = -EBUSY;
365
366 init_completion(&core_state->startup);
367 core_state->dumper.task = tsk;
368 core_state->dumper.next = NULL;
369
370 down_write(&mm->mmap_sem);
371 if (!mm->core_state)
372 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
373 up_write(&mm->mmap_sem);
374
375 if (core_waiters > 0) {
376 struct core_thread *ptr;
377
378 wait_for_completion(&core_state->startup);
379 /*
380 * Wait for all the threads to become inactive, so that
381 * all the thread context (extended register state, like
382 * fpu etc) gets copied to the memory.
383 */
384 ptr = core_state->dumper.next;
385 while (ptr != NULL) {
386 wait_task_inactive(ptr->task, 0);
387 ptr = ptr->next;
388 }
389 }
390
391 return core_waiters;
392}
393
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700394static void coredump_finish(struct mm_struct *mm, bool core_dumped)
Alex Kelly10c28d92012-09-26 21:52:08 -0400395{
396 struct core_thread *curr, *next;
397 struct task_struct *task;
398
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700399 spin_lock_irq(&current->sighand->siglock);
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700400 if (core_dumped && !__fatal_signal_pending(current))
401 current->signal->group_exit_code |= 0x80;
Oleg Nesterov6cd8f0a2013-04-30 15:28:12 -0700402 current->signal->group_exit_task = NULL;
403 current->signal->flags = SIGNAL_GROUP_EXIT;
404 spin_unlock_irq(&current->sighand->siglock);
405
Alex Kelly10c28d92012-09-26 21:52:08 -0400406 next = mm->core_state->dumper.next;
407 while ((curr = next) != NULL) {
408 next = curr->next;
409 task = curr->task;
410 /*
411 * see exit_mm(), curr->task must not see
412 * ->task == NULL before we read ->next.
413 */
414 smp_mb();
415 curr->task = NULL;
416 wake_up_process(task);
417 }
418
419 mm->core_state = NULL;
420}
421
Oleg Nesterov528f8272013-04-30 15:28:15 -0700422static bool dump_interrupted(void)
423{
424 /*
425 * SIGKILL or freezing() interrupt the coredumping. Perhaps we
426 * can do try_to_freeze() and check __fatal_signal_pending(),
427 * but then we need to teach dump_write() to restart and clear
428 * TIF_SIGPENDING.
429 */
430 return signal_pending(current);
431}
432
Alex Kelly10c28d92012-09-26 21:52:08 -0400433static void wait_for_dump_helpers(struct file *file)
434{
Al Virode32ec42013-03-21 11:16:56 -0400435 struct pipe_inode_info *pipe = file->private_data;
Alex Kelly10c28d92012-09-26 21:52:08 -0400436
437 pipe_lock(pipe);
438 pipe->readers++;
439 pipe->writers--;
Oleg Nesterovdc7ee2a2013-04-30 15:28:17 -0700440 wake_up_interruptible_sync(&pipe->wait);
441 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
442 pipe_unlock(pipe);
Alex Kelly10c28d92012-09-26 21:52:08 -0400443
Oleg Nesterovdc7ee2a2013-04-30 15:28:17 -0700444 /*
445 * We actually want wait_event_freezable() but then we need
446 * to clear TIF_SIGPENDING and improve dump_interrupted().
447 */
448 wait_event_interruptible(pipe->wait, pipe->readers == 1);
Alex Kelly10c28d92012-09-26 21:52:08 -0400449
Oleg Nesterovdc7ee2a2013-04-30 15:28:17 -0700450 pipe_lock(pipe);
Alex Kelly10c28d92012-09-26 21:52:08 -0400451 pipe->readers--;
452 pipe->writers++;
453 pipe_unlock(pipe);
Alex Kelly10c28d92012-09-26 21:52:08 -0400454}
455
456/*
457 * umh_pipe_setup
458 * helper function to customize the process used
459 * to collect the core in userspace. Specifically
460 * it sets up a pipe and installs it as fd 0 (stdin)
461 * for the process. Returns 0 on success, or
462 * PTR_ERR on failure.
463 * Note that it also sets the core limit to 1. This
464 * is a special value that we use to trap recursive
465 * core dumps
466 */
467static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
468{
469 struct file *files[2];
470 struct coredump_params *cp = (struct coredump_params *)info->data;
471 int err = create_pipe_files(files, 0);
472 if (err)
473 return err;
474
475 cp->file = files[1];
476
Al Viro45525b22012-10-16 13:30:07 -0400477 err = replace_fd(0, files[0], 0);
478 fput(files[0]);
Alex Kelly10c28d92012-09-26 21:52:08 -0400479 /* and disallow core files too */
480 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
481
Al Viro45525b22012-10-16 13:30:07 -0400482 return err;
Alex Kelly10c28d92012-09-26 21:52:08 -0400483}
484
Al Viro541880d2012-11-05 13:11:26 -0500485void do_coredump(siginfo_t *siginfo)
Alex Kelly10c28d92012-09-26 21:52:08 -0400486{
487 struct core_state core_state;
488 struct core_name cn;
489 struct mm_struct *mm = current->mm;
490 struct linux_binfmt * binfmt;
491 const struct cred *old_cred;
492 struct cred *cred;
493 int retval = 0;
494 int flag = 0;
495 int ispipe;
496 struct files_struct *displaced;
497 bool need_nonrelative = false;
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700498 bool core_dumped = false;
Alex Kelly10c28d92012-09-26 21:52:08 -0400499 static atomic_t core_dump_count = ATOMIC_INIT(0);
500 struct coredump_params cprm = {
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700501 .siginfo = siginfo,
Al Viro541880d2012-11-05 13:11:26 -0500502 .regs = signal_pt_regs(),
Alex Kelly10c28d92012-09-26 21:52:08 -0400503 .limit = rlimit(RLIMIT_CORE),
504 /*
505 * We must use the same mm->flags while dumping core to avoid
506 * inconsistency of bit flags, since this flag is not protected
507 * by any locks.
508 */
509 .mm_flags = mm->flags,
510 };
511
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700512 audit_core_dumps(siginfo->si_signo);
Alex Kelly10c28d92012-09-26 21:52:08 -0400513
514 binfmt = mm->binfmt;
515 if (!binfmt || !binfmt->core_dump)
516 goto fail;
517 if (!__get_dumpable(cprm.mm_flags))
518 goto fail;
519
520 cred = prepare_creds();
521 if (!cred)
522 goto fail;
523 /*
524 * We cannot trust fsuid as being the "true" uid of the process
525 * nor do we know its entire history. We only know it was tainted
526 * so we dump it as root in mode 2, and only into a controlled
527 * environment (pipe handler or fully qualified path).
528 */
Kees Cooke579d2c2013-02-27 17:03:15 -0800529 if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
Alex Kelly10c28d92012-09-26 21:52:08 -0400530 /* Setuid core dump mode */
531 flag = O_EXCL; /* Stop rewrite attacks */
532 cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */
533 need_nonrelative = true;
534 }
535
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700536 retval = coredump_wait(siginfo->si_signo, &core_state);
Alex Kelly10c28d92012-09-26 21:52:08 -0400537 if (retval < 0)
538 goto fail_creds;
539
540 old_cred = override_creds(cred);
541
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700542 ispipe = format_corename(&cn, &cprm);
Alex Kelly10c28d92012-09-26 21:52:08 -0400543
Lucas De Marchifb96c472013-04-30 15:28:06 -0700544 if (ispipe) {
Alex Kelly10c28d92012-09-26 21:52:08 -0400545 int dump_count;
546 char **helper_argv;
Lucas De Marchi907ed132013-04-30 15:28:07 -0700547 struct subprocess_info *sub_info;
Alex Kelly10c28d92012-09-26 21:52:08 -0400548
549 if (ispipe < 0) {
550 printk(KERN_WARNING "format_corename failed\n");
551 printk(KERN_WARNING "Aborting core\n");
552 goto fail_corename;
553 }
554
555 if (cprm.limit == 1) {
556 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
557 *
558 * Normally core limits are irrelevant to pipes, since
559 * we're not writing to the file system, but we use
560 * cprm.limit of 1 here as a speacial value, this is a
561 * consistent way to catch recursive crashes.
562 * We can still crash if the core_pattern binary sets
563 * RLIM_CORE = !1, but it runs as root, and can do
564 * lots of stupid things.
565 *
566 * Note that we use task_tgid_vnr here to grab the pid
567 * of the process group leader. That way we get the
568 * right pid if a thread in a multi-threaded
569 * core_pattern process dies.
570 */
571 printk(KERN_WARNING
572 "Process %d(%s) has RLIMIT_CORE set to 1\n",
573 task_tgid_vnr(current), current->comm);
574 printk(KERN_WARNING "Aborting core\n");
575 goto fail_unlock;
576 }
577 cprm.limit = RLIM_INFINITY;
578
579 dump_count = atomic_inc_return(&core_dump_count);
580 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
581 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
582 task_tgid_vnr(current), current->comm);
583 printk(KERN_WARNING "Skipping core dump\n");
584 goto fail_dropcount;
585 }
586
587 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
588 if (!helper_argv) {
589 printk(KERN_WARNING "%s failed to allocate memory\n",
590 __func__);
591 goto fail_dropcount;
592 }
593
Lucas De Marchi907ed132013-04-30 15:28:07 -0700594 retval = -ENOMEM;
595 sub_info = call_usermodehelper_setup(helper_argv[0],
596 helper_argv, NULL, GFP_KERNEL,
597 umh_pipe_setup, NULL, &cprm);
598 if (sub_info)
599 retval = call_usermodehelper_exec(sub_info,
600 UMH_WAIT_EXEC);
601
Alex Kelly10c28d92012-09-26 21:52:08 -0400602 argv_free(helper_argv);
603 if (retval) {
Lucas De Marchifb96c472013-04-30 15:28:06 -0700604 printk(KERN_INFO "Core dump to %s pipe failed\n",
Alex Kelly10c28d92012-09-26 21:52:08 -0400605 cn.corename);
606 goto close_fail;
Lucas De Marchifb96c472013-04-30 15:28:06 -0700607 }
Alex Kelly10c28d92012-09-26 21:52:08 -0400608 } else {
609 struct inode *inode;
610
611 if (cprm.limit < binfmt->min_coredump)
612 goto fail_unlock;
613
614 if (need_nonrelative && cn.corename[0] != '/') {
615 printk(KERN_WARNING "Pid %d(%s) can only dump core "\
616 "to fully qualified path!\n",
617 task_tgid_vnr(current), current->comm);
618 printk(KERN_WARNING "Skipping core dump\n");
619 goto fail_unlock;
620 }
621
622 cprm.file = filp_open(cn.corename,
623 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
624 0600);
625 if (IS_ERR(cprm.file))
626 goto fail_unlock;
627
Al Viro496ad9a2013-01-23 17:07:38 -0500628 inode = file_inode(cprm.file);
Alex Kelly10c28d92012-09-26 21:52:08 -0400629 if (inode->i_nlink > 1)
630 goto close_fail;
631 if (d_unhashed(cprm.file->f_path.dentry))
632 goto close_fail;
633 /*
634 * AK: actually i see no reason to not allow this for named
635 * pipes etc, but keep the previous behaviour for now.
636 */
637 if (!S_ISREG(inode->i_mode))
638 goto close_fail;
639 /*
640 * Dont allow local users get cute and trick others to coredump
641 * into their pre-created files.
642 */
643 if (!uid_eq(inode->i_uid, current_fsuid()))
644 goto close_fail;
645 if (!cprm.file->f_op || !cprm.file->f_op->write)
646 goto close_fail;
647 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
648 goto close_fail;
649 }
650
651 /* get us an unshared descriptor table; almost always a no-op */
652 retval = unshare_files(&displaced);
653 if (retval)
654 goto close_fail;
655 if (displaced)
656 put_files_struct(displaced);
Al Viroe86d35c2013-05-04 14:45:54 -0400657 if (!dump_interrupted()) {
658 file_start_write(cprm.file);
659 core_dumped = binfmt->core_dump(&cprm);
660 file_end_write(cprm.file);
661 }
Alex Kelly10c28d92012-09-26 21:52:08 -0400662 if (ispipe && core_pipe_limit)
663 wait_for_dump_helpers(cprm.file);
664close_fail:
665 if (cprm.file)
666 filp_close(cprm.file, NULL);
667fail_dropcount:
668 if (ispipe)
669 atomic_dec(&core_dump_count);
670fail_unlock:
671 kfree(cn.corename);
672fail_corename:
Oleg Nesterovacdedd92013-04-30 15:28:13 -0700673 coredump_finish(mm, core_dumped);
Alex Kelly10c28d92012-09-26 21:52:08 -0400674 revert_creds(old_cred);
675fail_creds:
676 put_cred(cred);
677fail:
678 return;
679}
680
681/*
682 * Core dumping helper functions. These are the only things you should
683 * do on a core-file: use only these functions to write out all the
684 * necessary info.
685 */
686int dump_write(struct file *file, const void *addr, int nr)
687{
Oleg Nesterov528f8272013-04-30 15:28:15 -0700688 return !dump_interrupted() &&
689 access_ok(VERIFY_READ, addr, nr) &&
690 file->f_op->write(file, addr, nr, &file->f_pos) == nr;
Alex Kelly10c28d92012-09-26 21:52:08 -0400691}
692EXPORT_SYMBOL(dump_write);
693
694int dump_seek(struct file *file, loff_t off)
695{
696 int ret = 1;
697
698 if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
Oleg Nesterov528f8272013-04-30 15:28:15 -0700699 if (dump_interrupted() ||
700 file->f_op->llseek(file, off, SEEK_CUR) < 0)
Alex Kelly10c28d92012-09-26 21:52:08 -0400701 return 0;
702 } else {
703 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
704
705 if (!buf)
706 return 0;
707 while (off > 0) {
708 unsigned long n = off;
709
710 if (n > PAGE_SIZE)
711 n = PAGE_SIZE;
712 if (!dump_write(file, buf, n)) {
713 ret = 0;
714 break;
715 }
716 off -= n;
717 }
718 free_page((unsigned long)buf);
719 }
720 return ret;
721}
722EXPORT_SYMBOL(dump_seek);