Merge tag 'cxl-for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl
[linux-2.6-microblaze.git] / fs / coredump.c
1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/slab.h>
3 #include <linux/file.h>
4 #include <linux/fdtable.h>
5 #include <linux/freezer.h>
6 #include <linux/mm.h>
7 #include <linux/stat.h>
8 #include <linux/fcntl.h>
9 #include <linux/swap.h>
10 #include <linux/ctype.h>
11 #include <linux/string.h>
12 #include <linux/init.h>
13 #include <linux/pagemap.h>
14 #include <linux/perf_event.h>
15 #include <linux/highmem.h>
16 #include <linux/spinlock.h>
17 #include <linux/key.h>
18 #include <linux/personality.h>
19 #include <linux/binfmts.h>
20 #include <linux/coredump.h>
21 #include <linux/sched/coredump.h>
22 #include <linux/sched/signal.h>
23 #include <linux/sched/task_stack.h>
24 #include <linux/utsname.h>
25 #include <linux/pid_namespace.h>
26 #include <linux/module.h>
27 #include <linux/namei.h>
28 #include <linux/mount.h>
29 #include <linux/security.h>
30 #include <linux/syscalls.h>
31 #include <linux/tsacct_kern.h>
32 #include <linux/cn_proc.h>
33 #include <linux/audit.h>
34 #include <linux/tracehook.h>
35 #include <linux/kmod.h>
36 #include <linux/fsnotify.h>
37 #include <linux/fs_struct.h>
38 #include <linux/pipe_fs_i.h>
39 #include <linux/oom.h>
40 #include <linux/compat.h>
41 #include <linux/fs.h>
42 #include <linux/path.h>
43 #include <linux/timekeeping.h>
44
45 #include <linux/uaccess.h>
46 #include <asm/mmu_context.h>
47 #include <asm/tlb.h>
48 #include <asm/exec.h>
49
50 #include <trace/events/task.h>
51 #include "internal.h"
52
53 #include <trace/events/sched.h>
54
55 int core_uses_pid;
56 unsigned int core_pipe_limit;
57 char core_pattern[CORENAME_MAX_SIZE] = "core";
58 static int core_name_size = CORENAME_MAX_SIZE;
59
60 struct core_name {
61         char *corename;
62         int used, size;
63 };
64
65 /* The maximal length of core_pattern is also specified in sysctl.c */
66
67 static int expand_corename(struct core_name *cn, int size)
68 {
69         char *corename = krealloc(cn->corename, size, GFP_KERNEL);
70
71         if (!corename)
72                 return -ENOMEM;
73
74         if (size > core_name_size) /* racy but harmless */
75                 core_name_size = size;
76
77         cn->size = ksize(corename);
78         cn->corename = corename;
79         return 0;
80 }
81
82 static __printf(2, 0) int cn_vprintf(struct core_name *cn, const char *fmt,
83                                      va_list arg)
84 {
85         int free, need;
86         va_list arg_copy;
87
88 again:
89         free = cn->size - cn->used;
90
91         va_copy(arg_copy, arg);
92         need = vsnprintf(cn->corename + cn->used, free, fmt, arg_copy);
93         va_end(arg_copy);
94
95         if (need < free) {
96                 cn->used += need;
97                 return 0;
98         }
99
100         if (!expand_corename(cn, cn->size + need - free + 1))
101                 goto again;
102
103         return -ENOMEM;
104 }
105
106 static __printf(2, 3) int cn_printf(struct core_name *cn, const char *fmt, ...)
107 {
108         va_list arg;
109         int ret;
110
111         va_start(arg, fmt);
112         ret = cn_vprintf(cn, fmt, arg);
113         va_end(arg);
114
115         return ret;
116 }
117
118 static __printf(2, 3)
119 int cn_esc_printf(struct core_name *cn, const char *fmt, ...)
120 {
121         int cur = cn->used;
122         va_list arg;
123         int ret;
124
125         va_start(arg, fmt);
126         ret = cn_vprintf(cn, fmt, arg);
127         va_end(arg);
128
129         if (ret == 0) {
130                 /*
131                  * Ensure that this coredump name component can't cause the
132                  * resulting corefile path to consist of a ".." or ".".
133                  */
134                 if ((cn->used - cur == 1 && cn->corename[cur] == '.') ||
135                                 (cn->used - cur == 2 && cn->corename[cur] == '.'
136                                 && cn->corename[cur+1] == '.'))
137                         cn->corename[cur] = '!';
138
139                 /*
140                  * Empty names are fishy and could be used to create a "//" in a
141                  * corefile name, causing the coredump to happen one directory
142                  * level too high. Enforce that all components of the core
143                  * pattern are at least one character long.
144                  */
145                 if (cn->used == cur)
146                         ret = cn_printf(cn, "!");
147         }
148
149         for (; cur < cn->used; ++cur) {
150                 if (cn->corename[cur] == '/')
151                         cn->corename[cur] = '!';
152         }
153         return ret;
154 }
155
156 static int cn_print_exe_file(struct core_name *cn, bool name_only)
157 {
158         struct file *exe_file;
159         char *pathbuf, *path, *ptr;
160         int ret;
161
162         exe_file = get_mm_exe_file(current->mm);
163         if (!exe_file)
164                 return cn_esc_printf(cn, "%s (path unknown)", current->comm);
165
166         pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
167         if (!pathbuf) {
168                 ret = -ENOMEM;
169                 goto put_exe_file;
170         }
171
172         path = file_path(exe_file, pathbuf, PATH_MAX);
173         if (IS_ERR(path)) {
174                 ret = PTR_ERR(path);
175                 goto free_buf;
176         }
177
178         if (name_only) {
179                 ptr = strrchr(path, '/');
180                 if (ptr)
181                         path = ptr + 1;
182         }
183         ret = cn_esc_printf(cn, "%s", path);
184
185 free_buf:
186         kfree(pathbuf);
187 put_exe_file:
188         fput(exe_file);
189         return ret;
190 }
191
192 /* format_corename will inspect the pattern parameter, and output a
193  * name into corename, which must have space for at least
194  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
195  */
196 static int format_corename(struct core_name *cn, struct coredump_params *cprm,
197                            size_t **argv, int *argc)
198 {
199         const struct cred *cred = current_cred();
200         const char *pat_ptr = core_pattern;
201         int ispipe = (*pat_ptr == '|');
202         bool was_space = false;
203         int pid_in_pattern = 0;
204         int err = 0;
205
206         cn->used = 0;
207         cn->corename = NULL;
208         if (expand_corename(cn, core_name_size))
209                 return -ENOMEM;
210         cn->corename[0] = '\0';
211
212         if (ispipe) {
213                 int argvs = sizeof(core_pattern) / 2;
214                 (*argv) = kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL);
215                 if (!(*argv))
216                         return -ENOMEM;
217                 (*argv)[(*argc)++] = 0;
218                 ++pat_ptr;
219                 if (!(*pat_ptr))
220                         return -ENOMEM;
221         }
222
223         /* Repeat as long as we have more pattern to process and more output
224            space */
225         while (*pat_ptr) {
226                 /*
227                  * Split on spaces before doing template expansion so that
228                  * %e and %E don't get split if they have spaces in them
229                  */
230                 if (ispipe) {
231                         if (isspace(*pat_ptr)) {
232                                 if (cn->used != 0)
233                                         was_space = true;
234                                 pat_ptr++;
235                                 continue;
236                         } else if (was_space) {
237                                 was_space = false;
238                                 err = cn_printf(cn, "%c", '\0');
239                                 if (err)
240                                         return err;
241                                 (*argv)[(*argc)++] = cn->used;
242                         }
243                 }
244                 if (*pat_ptr != '%') {
245                         err = cn_printf(cn, "%c", *pat_ptr++);
246                 } else {
247                         switch (*++pat_ptr) {
248                         /* single % at the end, drop that */
249                         case 0:
250                                 goto out;
251                         /* Double percent, output one percent */
252                         case '%':
253                                 err = cn_printf(cn, "%c", '%');
254                                 break;
255                         /* pid */
256                         case 'p':
257                                 pid_in_pattern = 1;
258                                 err = cn_printf(cn, "%d",
259                                               task_tgid_vnr(current));
260                                 break;
261                         /* global pid */
262                         case 'P':
263                                 err = cn_printf(cn, "%d",
264                                               task_tgid_nr(current));
265                                 break;
266                         case 'i':
267                                 err = cn_printf(cn, "%d",
268                                               task_pid_vnr(current));
269                                 break;
270                         case 'I':
271                                 err = cn_printf(cn, "%d",
272                                               task_pid_nr(current));
273                                 break;
274                         /* uid */
275                         case 'u':
276                                 err = cn_printf(cn, "%u",
277                                                 from_kuid(&init_user_ns,
278                                                           cred->uid));
279                                 break;
280                         /* gid */
281                         case 'g':
282                                 err = cn_printf(cn, "%u",
283                                                 from_kgid(&init_user_ns,
284                                                           cred->gid));
285                                 break;
286                         case 'd':
287                                 err = cn_printf(cn, "%d",
288                                         __get_dumpable(cprm->mm_flags));
289                                 break;
290                         /* signal that caused the coredump */
291                         case 's':
292                                 err = cn_printf(cn, "%d",
293                                                 cprm->siginfo->si_signo);
294                                 break;
295                         /* UNIX time of coredump */
296                         case 't': {
297                                 time64_t time;
298
299                                 time = ktime_get_real_seconds();
300                                 err = cn_printf(cn, "%lld", time);
301                                 break;
302                         }
303                         /* hostname */
304                         case 'h':
305                                 down_read(&uts_sem);
306                                 err = cn_esc_printf(cn, "%s",
307                                               utsname()->nodename);
308                                 up_read(&uts_sem);
309                                 break;
310                         /* executable, could be changed by prctl PR_SET_NAME etc */
311                         case 'e':
312                                 err = cn_esc_printf(cn, "%s", current->comm);
313                                 break;
314                         /* file name of executable */
315                         case 'f':
316                                 err = cn_print_exe_file(cn, true);
317                                 break;
318                         case 'E':
319                                 err = cn_print_exe_file(cn, false);
320                                 break;
321                         /* core limit size */
322                         case 'c':
323                                 err = cn_printf(cn, "%lu",
324                                               rlimit(RLIMIT_CORE));
325                                 break;
326                         default:
327                                 break;
328                         }
329                         ++pat_ptr;
330                 }
331
332                 if (err)
333                         return err;
334         }
335
336 out:
337         /* Backward compatibility with core_uses_pid:
338          *
339          * If core_pattern does not include a %p (as is the default)
340          * and core_uses_pid is set, then .%pid will be appended to
341          * the filename. Do not do this for piped commands. */
342         if (!ispipe && !pid_in_pattern && core_uses_pid) {
343                 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
344                 if (err)
345                         return err;
346         }
347         return ispipe;
348 }
349
350 static int zap_process(struct task_struct *start, int exit_code, int flags)
351 {
352         struct task_struct *t;
353         int nr = 0;
354
355         /* ignore all signals except SIGKILL, see prepare_signal() */
356         start->signal->flags = SIGNAL_GROUP_COREDUMP | flags;
357         start->signal->group_exit_code = exit_code;
358         start->signal->group_stop_count = 0;
359
360         for_each_thread(start, t) {
361                 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
362                 if (t != current && t->mm) {
363                         sigaddset(&t->pending.signal, SIGKILL);
364                         signal_wake_up(t, 1);
365                         nr++;
366                 }
367         }
368
369         return nr;
370 }
371
372 static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
373                         struct core_state *core_state, int exit_code)
374 {
375         struct task_struct *g, *p;
376         unsigned long flags;
377         int nr = -EAGAIN;
378
379         spin_lock_irq(&tsk->sighand->siglock);
380         if (!signal_group_exit(tsk->signal)) {
381                 mm->core_state = core_state;
382                 tsk->signal->group_exit_task = tsk;
383                 nr = zap_process(tsk, exit_code, 0);
384                 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
385         }
386         spin_unlock_irq(&tsk->sighand->siglock);
387         if (unlikely(nr < 0))
388                 return nr;
389
390         tsk->flags |= PF_DUMPCORE;
391         if (atomic_read(&mm->mm_users) == nr + 1)
392                 goto done;
393         /*
394          * We should find and kill all tasks which use this mm, and we should
395          * count them correctly into ->nr_threads. We don't take tasklist
396          * lock, but this is safe wrt:
397          *
398          * fork:
399          *      None of sub-threads can fork after zap_process(leader). All
400          *      processes which were created before this point should be
401          *      visible to zap_threads() because copy_process() adds the new
402          *      process to the tail of init_task.tasks list, and lock/unlock
403          *      of ->siglock provides a memory barrier.
404          *
405          * do_exit:
406          *      The caller holds mm->mmap_lock. This means that the task which
407          *      uses this mm can't pass exit_mm(), so it can't exit or clear
408          *      its ->mm.
409          *
410          * de_thread:
411          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
412          *      we must see either old or new leader, this does not matter.
413          *      However, it can change p->sighand, so lock_task_sighand(p)
414          *      must be used. Since p->mm != NULL and we hold ->mmap_lock
415          *      it can't fail.
416          *
417          *      Note also that "g" can be the old leader with ->mm == NULL
418          *      and already unhashed and thus removed from ->thread_group.
419          *      This is OK, __unhash_process()->list_del_rcu() does not
420          *      clear the ->next pointer, we will find the new leader via
421          *      next_thread().
422          */
423         rcu_read_lock();
424         for_each_process(g) {
425                 if (g == tsk->group_leader)
426                         continue;
427                 if (g->flags & PF_KTHREAD)
428                         continue;
429
430                 for_each_thread(g, p) {
431                         if (unlikely(!p->mm))
432                                 continue;
433                         if (unlikely(p->mm == mm)) {
434                                 lock_task_sighand(p, &flags);
435                                 nr += zap_process(p, exit_code,
436                                                         SIGNAL_GROUP_EXIT);
437                                 unlock_task_sighand(p, &flags);
438                         }
439                         break;
440                 }
441         }
442         rcu_read_unlock();
443 done:
444         atomic_set(&core_state->nr_threads, nr);
445         return nr;
446 }
447
448 static int coredump_wait(int exit_code, struct core_state *core_state)
449 {
450         struct task_struct *tsk = current;
451         struct mm_struct *mm = tsk->mm;
452         int core_waiters = -EBUSY;
453
454         init_completion(&core_state->startup);
455         core_state->dumper.task = tsk;
456         core_state->dumper.next = NULL;
457
458         if (mmap_write_lock_killable(mm))
459                 return -EINTR;
460
461         if (!mm->core_state)
462                 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
463         mmap_write_unlock(mm);
464
465         if (core_waiters > 0) {
466                 struct core_thread *ptr;
467
468                 freezer_do_not_count();
469                 wait_for_completion(&core_state->startup);
470                 freezer_count();
471                 /*
472                  * Wait for all the threads to become inactive, so that
473                  * all the thread context (extended register state, like
474                  * fpu etc) gets copied to the memory.
475                  */
476                 ptr = core_state->dumper.next;
477                 while (ptr != NULL) {
478                         wait_task_inactive(ptr->task, 0);
479                         ptr = ptr->next;
480                 }
481         }
482
483         return core_waiters;
484 }
485
486 static void coredump_finish(struct mm_struct *mm, bool core_dumped)
487 {
488         struct core_thread *curr, *next;
489         struct task_struct *task;
490
491         spin_lock_irq(&current->sighand->siglock);
492         if (core_dumped && !__fatal_signal_pending(current))
493                 current->signal->group_exit_code |= 0x80;
494         current->signal->group_exit_task = NULL;
495         current->signal->flags = SIGNAL_GROUP_EXIT;
496         spin_unlock_irq(&current->sighand->siglock);
497
498         next = mm->core_state->dumper.next;
499         while ((curr = next) != NULL) {
500                 next = curr->next;
501                 task = curr->task;
502                 /*
503                  * see exit_mm(), curr->task must not see
504                  * ->task == NULL before we read ->next.
505                  */
506                 smp_mb();
507                 curr->task = NULL;
508                 wake_up_process(task);
509         }
510
511         mm->core_state = NULL;
512 }
513
514 static bool dump_interrupted(void)
515 {
516         /*
517          * SIGKILL or freezing() interrupt the coredumping. Perhaps we
518          * can do try_to_freeze() and check __fatal_signal_pending(),
519          * but then we need to teach dump_write() to restart and clear
520          * TIF_SIGPENDING.
521          */
522         return fatal_signal_pending(current) || freezing(current);
523 }
524
525 static void wait_for_dump_helpers(struct file *file)
526 {
527         struct pipe_inode_info *pipe = file->private_data;
528
529         pipe_lock(pipe);
530         pipe->readers++;
531         pipe->writers--;
532         wake_up_interruptible_sync(&pipe->rd_wait);
533         kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
534         pipe_unlock(pipe);
535
536         /*
537          * We actually want wait_event_freezable() but then we need
538          * to clear TIF_SIGPENDING and improve dump_interrupted().
539          */
540         wait_event_interruptible(pipe->rd_wait, pipe->readers == 1);
541
542         pipe_lock(pipe);
543         pipe->readers--;
544         pipe->writers++;
545         pipe_unlock(pipe);
546 }
547
548 /*
549  * umh_pipe_setup
550  * helper function to customize the process used
551  * to collect the core in userspace.  Specifically
552  * it sets up a pipe and installs it as fd 0 (stdin)
553  * for the process.  Returns 0 on success, or
554  * PTR_ERR on failure.
555  * Note that it also sets the core limit to 1.  This
556  * is a special value that we use to trap recursive
557  * core dumps
558  */
559 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
560 {
561         struct file *files[2];
562         struct coredump_params *cp = (struct coredump_params *)info->data;
563         int err = create_pipe_files(files, 0);
564         if (err)
565                 return err;
566
567         cp->file = files[1];
568
569         err = replace_fd(0, files[0], 0);
570         fput(files[0]);
571         /* and disallow core files too */
572         current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
573
574         return err;
575 }
576
577 void do_coredump(const kernel_siginfo_t *siginfo)
578 {
579         struct core_state core_state;
580         struct core_name cn;
581         struct mm_struct *mm = current->mm;
582         struct linux_binfmt * binfmt;
583         const struct cred *old_cred;
584         struct cred *cred;
585         int retval = 0;
586         int ispipe;
587         size_t *argv = NULL;
588         int argc = 0;
589         /* require nonrelative corefile path and be extra careful */
590         bool need_suid_safe = false;
591         bool core_dumped = false;
592         static atomic_t core_dump_count = ATOMIC_INIT(0);
593         struct coredump_params cprm = {
594                 .siginfo = siginfo,
595                 .regs = signal_pt_regs(),
596                 .limit = rlimit(RLIMIT_CORE),
597                 /*
598                  * We must use the same mm->flags while dumping core to avoid
599                  * inconsistency of bit flags, since this flag is not protected
600                  * by any locks.
601                  */
602                 .mm_flags = mm->flags,
603         };
604
605         audit_core_dumps(siginfo->si_signo);
606
607         binfmt = mm->binfmt;
608         if (!binfmt || !binfmt->core_dump)
609                 goto fail;
610         if (!__get_dumpable(cprm.mm_flags))
611                 goto fail;
612
613         cred = prepare_creds();
614         if (!cred)
615                 goto fail;
616         /*
617          * We cannot trust fsuid as being the "true" uid of the process
618          * nor do we know its entire history. We only know it was tainted
619          * so we dump it as root in mode 2, and only into a controlled
620          * environment (pipe handler or fully qualified path).
621          */
622         if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
623                 /* Setuid core dump mode */
624                 cred->fsuid = GLOBAL_ROOT_UID;  /* Dump root private */
625                 need_suid_safe = true;
626         }
627
628         retval = coredump_wait(siginfo->si_signo, &core_state);
629         if (retval < 0)
630                 goto fail_creds;
631
632         old_cred = override_creds(cred);
633
634         ispipe = format_corename(&cn, &cprm, &argv, &argc);
635
636         if (ispipe) {
637                 int argi;
638                 int dump_count;
639                 char **helper_argv;
640                 struct subprocess_info *sub_info;
641
642                 if (ispipe < 0) {
643                         printk(KERN_WARNING "format_corename failed\n");
644                         printk(KERN_WARNING "Aborting core\n");
645                         goto fail_unlock;
646                 }
647
648                 if (cprm.limit == 1) {
649                         /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
650                          *
651                          * Normally core limits are irrelevant to pipes, since
652                          * we're not writing to the file system, but we use
653                          * cprm.limit of 1 here as a special value, this is a
654                          * consistent way to catch recursive crashes.
655                          * We can still crash if the core_pattern binary sets
656                          * RLIM_CORE = !1, but it runs as root, and can do
657                          * lots of stupid things.
658                          *
659                          * Note that we use task_tgid_vnr here to grab the pid
660                          * of the process group leader.  That way we get the
661                          * right pid if a thread in a multi-threaded
662                          * core_pattern process dies.
663                          */
664                         printk(KERN_WARNING
665                                 "Process %d(%s) has RLIMIT_CORE set to 1\n",
666                                 task_tgid_vnr(current), current->comm);
667                         printk(KERN_WARNING "Aborting core\n");
668                         goto fail_unlock;
669                 }
670                 cprm.limit = RLIM_INFINITY;
671
672                 dump_count = atomic_inc_return(&core_dump_count);
673                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
674                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
675                                task_tgid_vnr(current), current->comm);
676                         printk(KERN_WARNING "Skipping core dump\n");
677                         goto fail_dropcount;
678                 }
679
680                 helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv),
681                                             GFP_KERNEL);
682                 if (!helper_argv) {
683                         printk(KERN_WARNING "%s failed to allocate memory\n",
684                                __func__);
685                         goto fail_dropcount;
686                 }
687                 for (argi = 0; argi < argc; argi++)
688                         helper_argv[argi] = cn.corename + argv[argi];
689                 helper_argv[argi] = NULL;
690
691                 retval = -ENOMEM;
692                 sub_info = call_usermodehelper_setup(helper_argv[0],
693                                                 helper_argv, NULL, GFP_KERNEL,
694                                                 umh_pipe_setup, NULL, &cprm);
695                 if (sub_info)
696                         retval = call_usermodehelper_exec(sub_info,
697                                                           UMH_WAIT_EXEC);
698
699                 kfree(helper_argv);
700                 if (retval) {
701                         printk(KERN_INFO "Core dump to |%s pipe failed\n",
702                                cn.corename);
703                         goto close_fail;
704                 }
705         } else {
706                 struct user_namespace *mnt_userns;
707                 struct inode *inode;
708                 int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW |
709                                  O_LARGEFILE | O_EXCL;
710
711                 if (cprm.limit < binfmt->min_coredump)
712                         goto fail_unlock;
713
714                 if (need_suid_safe && cn.corename[0] != '/') {
715                         printk(KERN_WARNING "Pid %d(%s) can only dump core "\
716                                 "to fully qualified path!\n",
717                                 task_tgid_vnr(current), current->comm);
718                         printk(KERN_WARNING "Skipping core dump\n");
719                         goto fail_unlock;
720                 }
721
722                 /*
723                  * Unlink the file if it exists unless this is a SUID
724                  * binary - in that case, we're running around with root
725                  * privs and don't want to unlink another user's coredump.
726                  */
727                 if (!need_suid_safe) {
728                         /*
729                          * If it doesn't exist, that's fine. If there's some
730                          * other problem, we'll catch it at the filp_open().
731                          */
732                         do_unlinkat(AT_FDCWD, getname_kernel(cn.corename));
733                 }
734
735                 /*
736                  * There is a race between unlinking and creating the
737                  * file, but if that causes an EEXIST here, that's
738                  * fine - another process raced with us while creating
739                  * the corefile, and the other process won. To userspace,
740                  * what matters is that at least one of the two processes
741                  * writes its coredump successfully, not which one.
742                  */
743                 if (need_suid_safe) {
744                         /*
745                          * Using user namespaces, normal user tasks can change
746                          * their current->fs->root to point to arbitrary
747                          * directories. Since the intention of the "only dump
748                          * with a fully qualified path" rule is to control where
749                          * coredumps may be placed using root privileges,
750                          * current->fs->root must not be used. Instead, use the
751                          * root directory of init_task.
752                          */
753                         struct path root;
754
755                         task_lock(&init_task);
756                         get_fs_root(init_task.fs, &root);
757                         task_unlock(&init_task);
758                         cprm.file = file_open_root(&root, cn.corename,
759                                                    open_flags, 0600);
760                         path_put(&root);
761                 } else {
762                         cprm.file = filp_open(cn.corename, open_flags, 0600);
763                 }
764                 if (IS_ERR(cprm.file))
765                         goto fail_unlock;
766
767                 inode = file_inode(cprm.file);
768                 if (inode->i_nlink > 1)
769                         goto close_fail;
770                 if (d_unhashed(cprm.file->f_path.dentry))
771                         goto close_fail;
772                 /*
773                  * AK: actually i see no reason to not allow this for named
774                  * pipes etc, but keep the previous behaviour for now.
775                  */
776                 if (!S_ISREG(inode->i_mode))
777                         goto close_fail;
778                 /*
779                  * Don't dump core if the filesystem changed owner or mode
780                  * of the file during file creation. This is an issue when
781                  * a process dumps core while its cwd is e.g. on a vfat
782                  * filesystem.
783                  */
784                 mnt_userns = file_mnt_user_ns(cprm.file);
785                 if (!uid_eq(i_uid_into_mnt(mnt_userns, inode), current_fsuid()))
786                         goto close_fail;
787                 if ((inode->i_mode & 0677) != 0600)
788                         goto close_fail;
789                 if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
790                         goto close_fail;
791                 if (do_truncate(mnt_userns, cprm.file->f_path.dentry,
792                                 0, 0, cprm.file))
793                         goto close_fail;
794         }
795
796         /* get us an unshared descriptor table; almost always a no-op */
797         /* The cell spufs coredump code reads the file descriptor tables */
798         retval = unshare_files();
799         if (retval)
800                 goto close_fail;
801         if (!dump_interrupted()) {
802                 /*
803                  * umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would
804                  * have this set to NULL.
805                  */
806                 if (!cprm.file) {
807                         pr_info("Core dump to |%s disabled\n", cn.corename);
808                         goto close_fail;
809                 }
810                 file_start_write(cprm.file);
811                 core_dumped = binfmt->core_dump(&cprm);
812                 /*
813                  * Ensures that file size is big enough to contain the current
814                  * file postion. This prevents gdb from complaining about
815                  * a truncated file if the last "write" to the file was
816                  * dump_skip.
817                  */
818                 if (cprm.to_skip) {
819                         cprm.to_skip--;
820                         dump_emit(&cprm, "", 1);
821                 }
822                 file_end_write(cprm.file);
823         }
824         if (ispipe && core_pipe_limit)
825                 wait_for_dump_helpers(cprm.file);
826 close_fail:
827         if (cprm.file)
828                 filp_close(cprm.file, NULL);
829 fail_dropcount:
830         if (ispipe)
831                 atomic_dec(&core_dump_count);
832 fail_unlock:
833         kfree(argv);
834         kfree(cn.corename);
835         coredump_finish(mm, core_dumped);
836         revert_creds(old_cred);
837 fail_creds:
838         put_cred(cred);
839 fail:
840         return;
841 }
842
843 /*
844  * Core dumping helper functions.  These are the only things you should
845  * do on a core-file: use only these functions to write out all the
846  * necessary info.
847  */
848 static int __dump_emit(struct coredump_params *cprm, const void *addr, int nr)
849 {
850         struct file *file = cprm->file;
851         loff_t pos = file->f_pos;
852         ssize_t n;
853         if (cprm->written + nr > cprm->limit)
854                 return 0;
855
856
857         if (dump_interrupted())
858                 return 0;
859         n = __kernel_write(file, addr, nr, &pos);
860         if (n != nr)
861                 return 0;
862         file->f_pos = pos;
863         cprm->written += n;
864         cprm->pos += n;
865
866         return 1;
867 }
868
869 static int __dump_skip(struct coredump_params *cprm, size_t nr)
870 {
871         static char zeroes[PAGE_SIZE];
872         struct file *file = cprm->file;
873         if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
874                 if (dump_interrupted() ||
875                     file->f_op->llseek(file, nr, SEEK_CUR) < 0)
876                         return 0;
877                 cprm->pos += nr;
878                 return 1;
879         } else {
880                 while (nr > PAGE_SIZE) {
881                         if (!__dump_emit(cprm, zeroes, PAGE_SIZE))
882                                 return 0;
883                         nr -= PAGE_SIZE;
884                 }
885                 return __dump_emit(cprm, zeroes, nr);
886         }
887 }
888
889 int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
890 {
891         if (cprm->to_skip) {
892                 if (!__dump_skip(cprm, cprm->to_skip))
893                         return 0;
894                 cprm->to_skip = 0;
895         }
896         return __dump_emit(cprm, addr, nr);
897 }
898 EXPORT_SYMBOL(dump_emit);
899
900 void dump_skip_to(struct coredump_params *cprm, unsigned long pos)
901 {
902         cprm->to_skip = pos - cprm->pos;
903 }
904 EXPORT_SYMBOL(dump_skip_to);
905
906 void dump_skip(struct coredump_params *cprm, size_t nr)
907 {
908         cprm->to_skip += nr;
909 }
910 EXPORT_SYMBOL(dump_skip);
911
912 #ifdef CONFIG_ELF_CORE
913 int dump_user_range(struct coredump_params *cprm, unsigned long start,
914                     unsigned long len)
915 {
916         unsigned long addr;
917
918         for (addr = start; addr < start + len; addr += PAGE_SIZE) {
919                 struct page *page;
920                 int stop;
921
922                 /*
923                  * To avoid having to allocate page tables for virtual address
924                  * ranges that have never been used yet, and also to make it
925                  * easy to generate sparse core files, use a helper that returns
926                  * NULL when encountering an empty page table entry that would
927                  * otherwise have been filled with the zero page.
928                  */
929                 page = get_dump_page(addr);
930                 if (page) {
931                         void *kaddr = kmap_local_page(page);
932
933                         stop = !dump_emit(cprm, kaddr, PAGE_SIZE);
934                         kunmap_local(kaddr);
935                         put_page(page);
936                         if (stop)
937                                 return 0;
938                 } else {
939                         dump_skip(cprm, PAGE_SIZE);
940                 }
941         }
942         return 1;
943 }
944 #endif
945
946 int dump_align(struct coredump_params *cprm, int align)
947 {
948         unsigned mod = (cprm->pos + cprm->to_skip) & (align - 1);
949         if (align & (align - 1))
950                 return 0;
951         if (mod)
952                 cprm->to_skip += align - mod;
953         return 1;
954 }
955 EXPORT_SYMBOL(dump_align);
956
957 /*
958  * The purpose of always_dump_vma() is to make sure that special kernel mappings
959  * that are useful for post-mortem analysis are included in every core dump.
960  * In that way we ensure that the core dump is fully interpretable later
961  * without matching up the same kernel and hardware config to see what PC values
962  * meant. These special mappings include - vDSO, vsyscall, and other
963  * architecture specific mappings
964  */
965 static bool always_dump_vma(struct vm_area_struct *vma)
966 {
967         /* Any vsyscall mappings? */
968         if (vma == get_gate_vma(vma->vm_mm))
969                 return true;
970
971         /*
972          * Assume that all vmas with a .name op should always be dumped.
973          * If this changes, a new vm_ops field can easily be added.
974          */
975         if (vma->vm_ops && vma->vm_ops->name && vma->vm_ops->name(vma))
976                 return true;
977
978         /*
979          * arch_vma_name() returns non-NULL for special architecture mappings,
980          * such as vDSO sections.
981          */
982         if (arch_vma_name(vma))
983                 return true;
984
985         return false;
986 }
987
988 /*
989  * Decide how much of @vma's contents should be included in a core dump.
990  */
991 static unsigned long vma_dump_size(struct vm_area_struct *vma,
992                                    unsigned long mm_flags)
993 {
994 #define FILTER(type)    (mm_flags & (1UL << MMF_DUMP_##type))
995
996         /* always dump the vdso and vsyscall sections */
997         if (always_dump_vma(vma))
998                 goto whole;
999
1000         if (vma->vm_flags & VM_DONTDUMP)
1001                 return 0;
1002
1003         /* support for DAX */
1004         if (vma_is_dax(vma)) {
1005                 if ((vma->vm_flags & VM_SHARED) && FILTER(DAX_SHARED))
1006                         goto whole;
1007                 if (!(vma->vm_flags & VM_SHARED) && FILTER(DAX_PRIVATE))
1008                         goto whole;
1009                 return 0;
1010         }
1011
1012         /* Hugetlb memory check */
1013         if (is_vm_hugetlb_page(vma)) {
1014                 if ((vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_SHARED))
1015                         goto whole;
1016                 if (!(vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_PRIVATE))
1017                         goto whole;
1018                 return 0;
1019         }
1020
1021         /* Do not dump I/O mapped devices or special mappings */
1022         if (vma->vm_flags & VM_IO)
1023                 return 0;
1024
1025         /* By default, dump shared memory if mapped from an anonymous file. */
1026         if (vma->vm_flags & VM_SHARED) {
1027                 if (file_inode(vma->vm_file)->i_nlink == 0 ?
1028                     FILTER(ANON_SHARED) : FILTER(MAPPED_SHARED))
1029                         goto whole;
1030                 return 0;
1031         }
1032
1033         /* Dump segments that have been written to.  */
1034         if ((!IS_ENABLED(CONFIG_MMU) || vma->anon_vma) && FILTER(ANON_PRIVATE))
1035                 goto whole;
1036         if (vma->vm_file == NULL)
1037                 return 0;
1038
1039         if (FILTER(MAPPED_PRIVATE))
1040                 goto whole;
1041
1042         /*
1043          * If this is the beginning of an executable file mapping,
1044          * dump the first page to aid in determining what was mapped here.
1045          */
1046         if (FILTER(ELF_HEADERS) &&
1047             vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ) &&
1048             (READ_ONCE(file_inode(vma->vm_file)->i_mode) & 0111) != 0)
1049                 return PAGE_SIZE;
1050
1051 #undef  FILTER
1052
1053         return 0;
1054
1055 whole:
1056         return vma->vm_end - vma->vm_start;
1057 }
1058
1059 static struct vm_area_struct *first_vma(struct task_struct *tsk,
1060                                         struct vm_area_struct *gate_vma)
1061 {
1062         struct vm_area_struct *ret = tsk->mm->mmap;
1063
1064         if (ret)
1065                 return ret;
1066         return gate_vma;
1067 }
1068
1069 /*
1070  * Helper function for iterating across a vma list.  It ensures that the caller
1071  * will visit `gate_vma' prior to terminating the search.
1072  */
1073 static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma,
1074                                        struct vm_area_struct *gate_vma)
1075 {
1076         struct vm_area_struct *ret;
1077
1078         ret = this_vma->vm_next;
1079         if (ret)
1080                 return ret;
1081         if (this_vma == gate_vma)
1082                 return NULL;
1083         return gate_vma;
1084 }
1085
1086 /*
1087  * Under the mmap_lock, take a snapshot of relevant information about the task's
1088  * VMAs.
1089  */
1090 int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count,
1091                       struct core_vma_metadata **vma_meta,
1092                       size_t *vma_data_size_ptr)
1093 {
1094         struct vm_area_struct *vma, *gate_vma;
1095         struct mm_struct *mm = current->mm;
1096         int i;
1097         size_t vma_data_size = 0;
1098
1099         /*
1100          * Once the stack expansion code is fixed to not change VMA bounds
1101          * under mmap_lock in read mode, this can be changed to take the
1102          * mmap_lock in read mode.
1103          */
1104         if (mmap_write_lock_killable(mm))
1105                 return -EINTR;
1106
1107         gate_vma = get_gate_vma(mm);
1108         *vma_count = mm->map_count + (gate_vma ? 1 : 0);
1109
1110         *vma_meta = kvmalloc_array(*vma_count, sizeof(**vma_meta), GFP_KERNEL);
1111         if (!*vma_meta) {
1112                 mmap_write_unlock(mm);
1113                 return -ENOMEM;
1114         }
1115
1116         for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
1117                         vma = next_vma(vma, gate_vma), i++) {
1118                 struct core_vma_metadata *m = (*vma_meta) + i;
1119
1120                 m->start = vma->vm_start;
1121                 m->end = vma->vm_end;
1122                 m->flags = vma->vm_flags;
1123                 m->dump_size = vma_dump_size(vma, cprm->mm_flags);
1124
1125                 vma_data_size += m->dump_size;
1126         }
1127
1128         mmap_write_unlock(mm);
1129
1130         if (WARN_ON(i != *vma_count))
1131                 return -EFAULT;
1132
1133         *vma_data_size_ptr = vma_data_size;
1134         return 0;
1135 }