ARM: tegra: make device can run on UP
[linux-3.10.git] / fs / coredump.c
1 #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>
17 #include <linux/coredump.h>
18 #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"
43 #include "coredump.h"
44
45 #include <trace/events/sched.h>
46
47 int core_uses_pid;
48 char core_pattern[CORENAME_MAX_SIZE] = "core";
49 unsigned int core_pipe_limit;
50
51 struct core_name {
52         char *corename;
53         int used, size;
54 };
55 static atomic_t call_count = ATOMIC_INIT(1);
56
57 /* The maximal length of core_pattern is also specified in sysctl.c */
58
59 static 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
74 static 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
92 out_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
100 expand_fail:
101         return ret;
102 }
103
104 static void cn_escape(char *str)
105 {
106         for (; *str; str++)
107                 if (*str == '/')
108                         *str = '!';
109 }
110
111 static 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
141 free_buf:
142         kfree(pathbuf);
143 put_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  */
152 static int format_corename(struct core_name *cn, struct coredump_params *cprm)
153 {
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;
197                         case 'd':
198                                 err = cn_printf(cn, "%d",
199                                         __get_dumpable(cprm->mm_flags));
200                                 break;
201                         /* signal that caused the coredump */
202                         case 's':
203                                 err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
204                                 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         }
257 out:
258         return ispipe;
259 }
260
261 static int zap_process(struct task_struct *start, int exit_code)
262 {
263         struct task_struct *t;
264         int nr = 0;
265
266         start->signal->flags = SIGNAL_GROUP_EXIT;
267         start->signal->group_exit_code = exit_code;
268         start->signal->group_stop_count = 0;
269
270         t = start;
271         do {
272                 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
273                 if (t != current && t->mm) {
274                         sigaddset(&t->pending.signal, SIGKILL);
275                         signal_wake_up(t, 1);
276                         nr++;
277                 }
278         } while_each_thread(start, t);
279
280         return nr;
281 }
282
283 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
284                                 struct core_state *core_state, int exit_code)
285 {
286         struct task_struct *g, *p;
287         unsigned long flags;
288         int nr = -EAGAIN;
289
290         spin_lock_irq(&tsk->sighand->siglock);
291         if (!signal_group_exit(tsk->signal)) {
292                 mm->core_state = core_state;
293                 nr = zap_process(tsk, exit_code);
294         }
295         spin_unlock_irq(&tsk->sighand->siglock);
296         if (unlikely(nr < 0))
297                 return nr;
298
299         if (atomic_read(&mm->mm_users) == nr + 1)
300                 goto done;
301         /*
302          * We should find and kill all tasks which use this mm, and we should
303          * count them correctly into ->nr_threads. We don't take tasklist
304          * lock, but this is safe wrt:
305          *
306          * fork:
307          *      None of sub-threads can fork after zap_process(leader). All
308          *      processes which were created before this point should be
309          *      visible to zap_threads() because copy_process() adds the new
310          *      process to the tail of init_task.tasks list, and lock/unlock
311          *      of ->siglock provides a memory barrier.
312          *
313          * do_exit:
314          *      The caller holds mm->mmap_sem. This means that the task which
315          *      uses this mm can't pass exit_mm(), so it can't exit or clear
316          *      its ->mm.
317          *
318          * de_thread:
319          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
320          *      we must see either old or new leader, this does not matter.
321          *      However, it can change p->sighand, so lock_task_sighand(p)
322          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
323          *      it can't fail.
324          *
325          *      Note also that "g" can be the old leader with ->mm == NULL
326          *      and already unhashed and thus removed from ->thread_group.
327          *      This is OK, __unhash_process()->list_del_rcu() does not
328          *      clear the ->next pointer, we will find the new leader via
329          *      next_thread().
330          */
331         rcu_read_lock();
332         for_each_process(g) {
333                 if (g == tsk->group_leader)
334                         continue;
335                 if (g->flags & PF_KTHREAD)
336                         continue;
337                 p = g;
338                 do {
339                         if (p->mm) {
340                                 if (unlikely(p->mm == mm)) {
341                                         lock_task_sighand(p, &flags);
342                                         nr += zap_process(p, exit_code);
343                                         unlock_task_sighand(p, &flags);
344                                 }
345                                 break;
346                         }
347                 } while_each_thread(g, p);
348         }
349         rcu_read_unlock();
350 done:
351         atomic_set(&core_state->nr_threads, nr);
352         return nr;
353 }
354
355 static int coredump_wait(int exit_code, struct core_state *core_state)
356 {
357         struct task_struct *tsk = current;
358         struct mm_struct *mm = tsk->mm;
359         int core_waiters = -EBUSY;
360
361         init_completion(&core_state->startup);
362         core_state->dumper.task = tsk;
363         core_state->dumper.next = NULL;
364
365         down_write(&mm->mmap_sem);
366         if (!mm->core_state)
367                 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
368         up_write(&mm->mmap_sem);
369
370         if (core_waiters > 0) {
371                 struct core_thread *ptr;
372
373                 wait_for_completion(&core_state->startup);
374                 /*
375                  * Wait for all the threads to become inactive, so that
376                  * all the thread context (extended register state, like
377                  * fpu etc) gets copied to the memory.
378                  */
379                 ptr = core_state->dumper.next;
380                 while (ptr != NULL) {
381                         wait_task_inactive(ptr->task, 0);
382                         ptr = ptr->next;
383                 }
384         }
385
386         return core_waiters;
387 }
388
389 static void coredump_finish(struct mm_struct *mm)
390 {
391         struct core_thread *curr, *next;
392         struct task_struct *task;
393
394         next = mm->core_state->dumper.next;
395         while ((curr = next) != NULL) {
396                 next = curr->next;
397                 task = curr->task;
398                 /*
399                  * see exit_mm(), curr->task must not see
400                  * ->task == NULL before we read ->next.
401                  */
402                 smp_mb();
403                 curr->task = NULL;
404                 wake_up_process(task);
405         }
406
407         mm->core_state = NULL;
408 }
409
410 static void wait_for_dump_helpers(struct file *file)
411 {
412         struct pipe_inode_info *pipe;
413
414         pipe = file->f_path.dentry->d_inode->i_pipe;
415
416         pipe_lock(pipe);
417         pipe->readers++;
418         pipe->writers--;
419
420         while ((pipe->readers > 1) && (!signal_pending(current))) {
421                 wake_up_interruptible_sync(&pipe->wait);
422                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
423                 pipe_wait(pipe);
424         }
425
426         pipe->readers--;
427         pipe->writers++;
428         pipe_unlock(pipe);
429
430 }
431
432 /*
433  * umh_pipe_setup
434  * helper function to customize the process used
435  * to collect the core in userspace.  Specifically
436  * it sets up a pipe and installs it as fd 0 (stdin)
437  * for the process.  Returns 0 on success, or
438  * PTR_ERR on failure.
439  * Note that it also sets the core limit to 1.  This
440  * is a special value that we use to trap recursive
441  * core dumps
442  */
443 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
444 {
445         struct file *files[2];
446         struct coredump_params *cp = (struct coredump_params *)info->data;
447         int err = create_pipe_files(files, 0);
448         if (err)
449                 return err;
450
451         cp->file = files[1];
452
453         err = replace_fd(0, files[0], 0);
454         fput(files[0]);
455         /* and disallow core files too */
456         current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
457
458         return err;
459 }
460
461 void do_coredump(siginfo_t *siginfo)
462 {
463         struct core_state core_state;
464         struct core_name cn;
465         struct mm_struct *mm = current->mm;
466         struct linux_binfmt * binfmt;
467         const struct cred *old_cred;
468         struct cred *cred;
469         int retval = 0;
470         int flag = 0;
471         int ispipe;
472         struct files_struct *displaced;
473         bool need_nonrelative = false;
474         static atomic_t core_dump_count = ATOMIC_INIT(0);
475         struct coredump_params cprm = {
476                 .siginfo = siginfo,
477                 .regs = signal_pt_regs(),
478                 .limit = rlimit(RLIMIT_CORE),
479                 /*
480                  * We must use the same mm->flags while dumping core to avoid
481                  * inconsistency of bit flags, since this flag is not protected
482                  * by any locks.
483                  */
484                 .mm_flags = mm->flags,
485         };
486
487         audit_core_dumps(siginfo->si_signo);
488
489         binfmt = mm->binfmt;
490         if (!binfmt || !binfmt->core_dump)
491                 goto fail;
492         if (!__get_dumpable(cprm.mm_flags))
493                 goto fail;
494
495         cred = prepare_creds();
496         if (!cred)
497                 goto fail;
498         /*
499          * We cannot trust fsuid as being the "true" uid of the process
500          * nor do we know its entire history. We only know it was tainted
501          * so we dump it as root in mode 2, and only into a controlled
502          * environment (pipe handler or fully qualified path).
503          */
504         if (__get_dumpable(cprm.mm_flags) == SUID_DUMPABLE_SAFE) {
505                 /* Setuid core dump mode */
506                 flag = O_EXCL;          /* Stop rewrite attacks */
507                 cred->fsuid = GLOBAL_ROOT_UID;  /* Dump root private */
508                 need_nonrelative = true;
509         }
510
511         retval = coredump_wait(siginfo->si_signo, &core_state);
512         if (retval < 0)
513                 goto fail_creds;
514
515         old_cred = override_creds(cred);
516
517         /*
518          * Clear any false indication of pending signals that might
519          * be seen by the filesystem code called to write the core file.
520          */
521         clear_thread_flag(TIF_SIGPENDING);
522
523         ispipe = format_corename(&cn, &cprm);
524
525         if (ispipe) {
526                 int dump_count;
527                 char **helper_argv;
528
529                 if (ispipe < 0) {
530                         printk(KERN_WARNING "format_corename failed\n");
531                         printk(KERN_WARNING "Aborting core\n");
532                         goto fail_corename;
533                 }
534
535                 if (cprm.limit == 1) {
536                         /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
537                          *
538                          * Normally core limits are irrelevant to pipes, since
539                          * we're not writing to the file system, but we use
540                          * cprm.limit of 1 here as a speacial value, this is a
541                          * consistent way to catch recursive crashes.
542                          * We can still crash if the core_pattern binary sets
543                          * RLIM_CORE = !1, but it runs as root, and can do
544                          * lots of stupid things.
545                          *
546                          * Note that we use task_tgid_vnr here to grab the pid
547                          * of the process group leader.  That way we get the
548                          * right pid if a thread in a multi-threaded
549                          * core_pattern process dies.
550                          */
551                         printk(KERN_WARNING
552                                 "Process %d(%s) has RLIMIT_CORE set to 1\n",
553                                 task_tgid_vnr(current), current->comm);
554                         printk(KERN_WARNING "Aborting core\n");
555                         goto fail_unlock;
556                 }
557                 cprm.limit = RLIM_INFINITY;
558
559                 dump_count = atomic_inc_return(&core_dump_count);
560                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
561                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
562                                task_tgid_vnr(current), current->comm);
563                         printk(KERN_WARNING "Skipping core dump\n");
564                         goto fail_dropcount;
565                 }
566
567                 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
568                 if (!helper_argv) {
569                         printk(KERN_WARNING "%s failed to allocate memory\n",
570                                __func__);
571                         goto fail_dropcount;
572                 }
573
574                 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
575                                         NULL, UMH_WAIT_EXEC, umh_pipe_setup,
576                                         NULL, &cprm);
577                 argv_free(helper_argv);
578                 if (retval) {
579                         printk(KERN_INFO "Core dump to %s pipe failed\n",
580                                cn.corename);
581                         goto close_fail;
582                 }
583         } else {
584                 struct inode *inode;
585
586                 if (cprm.limit < binfmt->min_coredump)
587                         goto fail_unlock;
588
589                 if (need_nonrelative && cn.corename[0] != '/') {
590                         printk(KERN_WARNING "Pid %d(%s) can only dump core "\
591                                 "to fully qualified path!\n",
592                                 task_tgid_vnr(current), current->comm);
593                         printk(KERN_WARNING "Skipping core dump\n");
594                         goto fail_unlock;
595                 }
596
597                 cprm.file = filp_open(cn.corename,
598                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
599                                  0600);
600                 if (IS_ERR(cprm.file))
601                         goto fail_unlock;
602
603                 inode = cprm.file->f_path.dentry->d_inode;
604                 if (inode->i_nlink > 1)
605                         goto close_fail;
606                 if (d_unhashed(cprm.file->f_path.dentry))
607                         goto close_fail;
608                 /*
609                  * AK: actually i see no reason to not allow this for named
610                  * pipes etc, but keep the previous behaviour for now.
611                  */
612                 if (!S_ISREG(inode->i_mode))
613                         goto close_fail;
614                 /*
615                  * Dont allow local users get cute and trick others to coredump
616                  * into their pre-created files.
617                  */
618                 if (!uid_eq(inode->i_uid, current_fsuid()))
619                         goto close_fail;
620                 if (!cprm.file->f_op || !cprm.file->f_op->write)
621                         goto close_fail;
622                 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
623                         goto close_fail;
624         }
625
626         /* get us an unshared descriptor table; almost always a no-op */
627         retval = unshare_files(&displaced);
628         if (retval)
629                 goto close_fail;
630         if (displaced)
631                 put_files_struct(displaced);
632         retval = binfmt->core_dump(&cprm);
633         if (retval)
634                 current->signal->group_exit_code |= 0x80;
635
636         if (ispipe && core_pipe_limit)
637                 wait_for_dump_helpers(cprm.file);
638 close_fail:
639         if (cprm.file)
640                 filp_close(cprm.file, NULL);
641 fail_dropcount:
642         if (ispipe)
643                 atomic_dec(&core_dump_count);
644 fail_unlock:
645         kfree(cn.corename);
646 fail_corename:
647         coredump_finish(mm);
648         revert_creds(old_cred);
649 fail_creds:
650         put_cred(cred);
651 fail:
652         return;
653 }
654
655 /*
656  * Core dumping helper functions.  These are the only things you should
657  * do on a core-file: use only these functions to write out all the
658  * necessary info.
659  */
660 int dump_write(struct file *file, const void *addr, int nr)
661 {
662         return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
663 }
664 EXPORT_SYMBOL(dump_write);
665
666 int dump_seek(struct file *file, loff_t off)
667 {
668         int ret = 1;
669
670         if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
671                 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
672                         return 0;
673         } else {
674                 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
675
676                 if (!buf)
677                         return 0;
678                 while (off > 0) {
679                         unsigned long n = off;
680
681                         if (n > PAGE_SIZE)
682                                 n = PAGE_SIZE;
683                         if (!dump_write(file, buf, n)) {
684                                 ret = 0;
685                                 break;
686                         }
687                         off -= n;
688                 }
689                 free_page((unsigned long)buf);
690         }
691         return ret;
692 }
693 EXPORT_SYMBOL(dump_seek);