Merge tag 'mips_6.5_1' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux
[platform/kernel/linux-starfive.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/kmod.h>
35 #include <linux/fsnotify.h>
36 #include <linux/fs_struct.h>
37 #include <linux/pipe_fs_i.h>
38 #include <linux/oom.h>
39 #include <linux/compat.h>
40 #include <linux/fs.h>
41 #include <linux/path.h>
42 #include <linux/timekeeping.h>
43 #include <linux/sysctl.h>
44 #include <linux/elf.h>
45
46 #include <linux/uaccess.h>
47 #include <asm/mmu_context.h>
48 #include <asm/tlb.h>
49 #include <asm/exec.h>
50
51 #include <trace/events/task.h>
52 #include "internal.h"
53
54 #include <trace/events/sched.h>
55
56 static bool dump_vma_snapshot(struct coredump_params *cprm);
57 static void free_vma_snapshot(struct coredump_params *cprm);
58
59 static int core_uses_pid;
60 static unsigned int core_pipe_limit;
61 static char core_pattern[CORENAME_MAX_SIZE] = "core";
62 static int core_name_size = CORENAME_MAX_SIZE;
63
64 struct core_name {
65         char *corename;
66         int used, size;
67 };
68
69 static int expand_corename(struct core_name *cn, int size)
70 {
71         char *corename;
72
73         size = kmalloc_size_roundup(size);
74         corename = krealloc(cn->corename, size, GFP_KERNEL);
75
76         if (!corename)
77                 return -ENOMEM;
78
79         if (size > core_name_size) /* racy but harmless */
80                 core_name_size = size;
81
82         cn->size = size;
83         cn->corename = corename;
84         return 0;
85 }
86
87 static __printf(2, 0) int cn_vprintf(struct core_name *cn, const char *fmt,
88                                      va_list arg)
89 {
90         int free, need;
91         va_list arg_copy;
92
93 again:
94         free = cn->size - cn->used;
95
96         va_copy(arg_copy, arg);
97         need = vsnprintf(cn->corename + cn->used, free, fmt, arg_copy);
98         va_end(arg_copy);
99
100         if (need < free) {
101                 cn->used += need;
102                 return 0;
103         }
104
105         if (!expand_corename(cn, cn->size + need - free + 1))
106                 goto again;
107
108         return -ENOMEM;
109 }
110
111 static __printf(2, 3) int cn_printf(struct core_name *cn, const char *fmt, ...)
112 {
113         va_list arg;
114         int ret;
115
116         va_start(arg, fmt);
117         ret = cn_vprintf(cn, fmt, arg);
118         va_end(arg);
119
120         return ret;
121 }
122
123 static __printf(2, 3)
124 int cn_esc_printf(struct core_name *cn, const char *fmt, ...)
125 {
126         int cur = cn->used;
127         va_list arg;
128         int ret;
129
130         va_start(arg, fmt);
131         ret = cn_vprintf(cn, fmt, arg);
132         va_end(arg);
133
134         if (ret == 0) {
135                 /*
136                  * Ensure that this coredump name component can't cause the
137                  * resulting corefile path to consist of a ".." or ".".
138                  */
139                 if ((cn->used - cur == 1 && cn->corename[cur] == '.') ||
140                                 (cn->used - cur == 2 && cn->corename[cur] == '.'
141                                 && cn->corename[cur+1] == '.'))
142                         cn->corename[cur] = '!';
143
144                 /*
145                  * Empty names are fishy and could be used to create a "//" in a
146                  * corefile name, causing the coredump to happen one directory
147                  * level too high. Enforce that all components of the core
148                  * pattern are at least one character long.
149                  */
150                 if (cn->used == cur)
151                         ret = cn_printf(cn, "!");
152         }
153
154         for (; cur < cn->used; ++cur) {
155                 if (cn->corename[cur] == '/')
156                         cn->corename[cur] = '!';
157         }
158         return ret;
159 }
160
161 static int cn_print_exe_file(struct core_name *cn, bool name_only)
162 {
163         struct file *exe_file;
164         char *pathbuf, *path, *ptr;
165         int ret;
166
167         exe_file = get_mm_exe_file(current->mm);
168         if (!exe_file)
169                 return cn_esc_printf(cn, "%s (path unknown)", current->comm);
170
171         pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
172         if (!pathbuf) {
173                 ret = -ENOMEM;
174                 goto put_exe_file;
175         }
176
177         path = file_path(exe_file, pathbuf, PATH_MAX);
178         if (IS_ERR(path)) {
179                 ret = PTR_ERR(path);
180                 goto free_buf;
181         }
182
183         if (name_only) {
184                 ptr = strrchr(path, '/');
185                 if (ptr)
186                         path = ptr + 1;
187         }
188         ret = cn_esc_printf(cn, "%s", path);
189
190 free_buf:
191         kfree(pathbuf);
192 put_exe_file:
193         fput(exe_file);
194         return ret;
195 }
196
197 /* format_corename will inspect the pattern parameter, and output a
198  * name into corename, which must have space for at least
199  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
200  */
201 static int format_corename(struct core_name *cn, struct coredump_params *cprm,
202                            size_t **argv, int *argc)
203 {
204         const struct cred *cred = current_cred();
205         const char *pat_ptr = core_pattern;
206         int ispipe = (*pat_ptr == '|');
207         bool was_space = false;
208         int pid_in_pattern = 0;
209         int err = 0;
210
211         cn->used = 0;
212         cn->corename = NULL;
213         if (expand_corename(cn, core_name_size))
214                 return -ENOMEM;
215         cn->corename[0] = '\0';
216
217         if (ispipe) {
218                 int argvs = sizeof(core_pattern) / 2;
219                 (*argv) = kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL);
220                 if (!(*argv))
221                         return -ENOMEM;
222                 (*argv)[(*argc)++] = 0;
223                 ++pat_ptr;
224                 if (!(*pat_ptr))
225                         return -ENOMEM;
226         }
227
228         /* Repeat as long as we have more pattern to process and more output
229            space */
230         while (*pat_ptr) {
231                 /*
232                  * Split on spaces before doing template expansion so that
233                  * %e and %E don't get split if they have spaces in them
234                  */
235                 if (ispipe) {
236                         if (isspace(*pat_ptr)) {
237                                 if (cn->used != 0)
238                                         was_space = true;
239                                 pat_ptr++;
240                                 continue;
241                         } else if (was_space) {
242                                 was_space = false;
243                                 err = cn_printf(cn, "%c", '\0');
244                                 if (err)
245                                         return err;
246                                 (*argv)[(*argc)++] = cn->used;
247                         }
248                 }
249                 if (*pat_ptr != '%') {
250                         err = cn_printf(cn, "%c", *pat_ptr++);
251                 } else {
252                         switch (*++pat_ptr) {
253                         /* single % at the end, drop that */
254                         case 0:
255                                 goto out;
256                         /* Double percent, output one percent */
257                         case '%':
258                                 err = cn_printf(cn, "%c", '%');
259                                 break;
260                         /* pid */
261                         case 'p':
262                                 pid_in_pattern = 1;
263                                 err = cn_printf(cn, "%d",
264                                               task_tgid_vnr(current));
265                                 break;
266                         /* global pid */
267                         case 'P':
268                                 err = cn_printf(cn, "%d",
269                                               task_tgid_nr(current));
270                                 break;
271                         case 'i':
272                                 err = cn_printf(cn, "%d",
273                                               task_pid_vnr(current));
274                                 break;
275                         case 'I':
276                                 err = cn_printf(cn, "%d",
277                                               task_pid_nr(current));
278                                 break;
279                         /* uid */
280                         case 'u':
281                                 err = cn_printf(cn, "%u",
282                                                 from_kuid(&init_user_ns,
283                                                           cred->uid));
284                                 break;
285                         /* gid */
286                         case 'g':
287                                 err = cn_printf(cn, "%u",
288                                                 from_kgid(&init_user_ns,
289                                                           cred->gid));
290                                 break;
291                         case 'd':
292                                 err = cn_printf(cn, "%d",
293                                         __get_dumpable(cprm->mm_flags));
294                                 break;
295                         /* signal that caused the coredump */
296                         case 's':
297                                 err = cn_printf(cn, "%d",
298                                                 cprm->siginfo->si_signo);
299                                 break;
300                         /* UNIX time of coredump */
301                         case 't': {
302                                 time64_t time;
303
304                                 time = ktime_get_real_seconds();
305                                 err = cn_printf(cn, "%lld", time);
306                                 break;
307                         }
308                         /* hostname */
309                         case 'h':
310                                 down_read(&uts_sem);
311                                 err = cn_esc_printf(cn, "%s",
312                                               utsname()->nodename);
313                                 up_read(&uts_sem);
314                                 break;
315                         /* executable, could be changed by prctl PR_SET_NAME etc */
316                         case 'e':
317                                 err = cn_esc_printf(cn, "%s", current->comm);
318                                 break;
319                         /* file name of executable */
320                         case 'f':
321                                 err = cn_print_exe_file(cn, true);
322                                 break;
323                         case 'E':
324                                 err = cn_print_exe_file(cn, false);
325                                 break;
326                         /* core limit size */
327                         case 'c':
328                                 err = cn_printf(cn, "%lu",
329                                               rlimit(RLIMIT_CORE));
330                                 break;
331                         /* CPU the task ran on */
332                         case 'C':
333                                 err = cn_printf(cn, "%d", cprm->cpu);
334                                 break;
335                         default:
336                                 break;
337                         }
338                         ++pat_ptr;
339                 }
340
341                 if (err)
342                         return err;
343         }
344
345 out:
346         /* Backward compatibility with core_uses_pid:
347          *
348          * If core_pattern does not include a %p (as is the default)
349          * and core_uses_pid is set, then .%pid will be appended to
350          * the filename. Do not do this for piped commands. */
351         if (!ispipe && !pid_in_pattern && core_uses_pid) {
352                 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
353                 if (err)
354                         return err;
355         }
356         return ispipe;
357 }
358
359 static int zap_process(struct task_struct *start, int exit_code)
360 {
361         struct task_struct *t;
362         int nr = 0;
363
364         /* Allow SIGKILL, see prepare_signal() */
365         start->signal->flags = SIGNAL_GROUP_EXIT;
366         start->signal->group_exit_code = exit_code;
367         start->signal->group_stop_count = 0;
368
369         for_each_thread(start, t) {
370                 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
371                 if (t != current && !(t->flags & PF_POSTCOREDUMP)) {
372                         sigaddset(&t->pending.signal, SIGKILL);
373                         signal_wake_up(t, 1);
374                         /* The vhost_worker does not particpate in coredumps */
375                         if ((t->flags & (PF_USER_WORKER | PF_IO_WORKER)) != PF_USER_WORKER)
376                                 nr++;
377                 }
378         }
379
380         return nr;
381 }
382
383 static int zap_threads(struct task_struct *tsk,
384                         struct core_state *core_state, int exit_code)
385 {
386         struct signal_struct *signal = tsk->signal;
387         int nr = -EAGAIN;
388
389         spin_lock_irq(&tsk->sighand->siglock);
390         if (!(signal->flags & SIGNAL_GROUP_EXIT) && !signal->group_exec_task) {
391                 signal->core_state = core_state;
392                 nr = zap_process(tsk, exit_code);
393                 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
394                 tsk->flags |= PF_DUMPCORE;
395                 atomic_set(&core_state->nr_threads, nr);
396         }
397         spin_unlock_irq(&tsk->sighand->siglock);
398         return nr;
399 }
400
401 static int coredump_wait(int exit_code, struct core_state *core_state)
402 {
403         struct task_struct *tsk = current;
404         int core_waiters = -EBUSY;
405
406         init_completion(&core_state->startup);
407         core_state->dumper.task = tsk;
408         core_state->dumper.next = NULL;
409
410         core_waiters = zap_threads(tsk, core_state, exit_code);
411         if (core_waiters > 0) {
412                 struct core_thread *ptr;
413
414                 wait_for_completion_state(&core_state->startup,
415                                           TASK_UNINTERRUPTIBLE|TASK_FREEZABLE);
416                 /*
417                  * Wait for all the threads to become inactive, so that
418                  * all the thread context (extended register state, like
419                  * fpu etc) gets copied to the memory.
420                  */
421                 ptr = core_state->dumper.next;
422                 while (ptr != NULL) {
423                         wait_task_inactive(ptr->task, TASK_ANY);
424                         ptr = ptr->next;
425                 }
426         }
427
428         return core_waiters;
429 }
430
431 static void coredump_finish(bool core_dumped)
432 {
433         struct core_thread *curr, *next;
434         struct task_struct *task;
435
436         spin_lock_irq(&current->sighand->siglock);
437         if (core_dumped && !__fatal_signal_pending(current))
438                 current->signal->group_exit_code |= 0x80;
439         next = current->signal->core_state->dumper.next;
440         current->signal->core_state = NULL;
441         spin_unlock_irq(&current->sighand->siglock);
442
443         while ((curr = next) != NULL) {
444                 next = curr->next;
445                 task = curr->task;
446                 /*
447                  * see coredump_task_exit(), curr->task must not see
448                  * ->task == NULL before we read ->next.
449                  */
450                 smp_mb();
451                 curr->task = NULL;
452                 wake_up_process(task);
453         }
454 }
455
456 static bool dump_interrupted(void)
457 {
458         /*
459          * SIGKILL or freezing() interrupt the coredumping. Perhaps we
460          * can do try_to_freeze() and check __fatal_signal_pending(),
461          * but then we need to teach dump_write() to restart and clear
462          * TIF_SIGPENDING.
463          */
464         return fatal_signal_pending(current) || freezing(current);
465 }
466
467 static void wait_for_dump_helpers(struct file *file)
468 {
469         struct pipe_inode_info *pipe = file->private_data;
470
471         pipe_lock(pipe);
472         pipe->readers++;
473         pipe->writers--;
474         wake_up_interruptible_sync(&pipe->rd_wait);
475         kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
476         pipe_unlock(pipe);
477
478         /*
479          * We actually want wait_event_freezable() but then we need
480          * to clear TIF_SIGPENDING and improve dump_interrupted().
481          */
482         wait_event_interruptible(pipe->rd_wait, pipe->readers == 1);
483
484         pipe_lock(pipe);
485         pipe->readers--;
486         pipe->writers++;
487         pipe_unlock(pipe);
488 }
489
490 /*
491  * umh_pipe_setup
492  * helper function to customize the process used
493  * to collect the core in userspace.  Specifically
494  * it sets up a pipe and installs it as fd 0 (stdin)
495  * for the process.  Returns 0 on success, or
496  * PTR_ERR on failure.
497  * Note that it also sets the core limit to 1.  This
498  * is a special value that we use to trap recursive
499  * core dumps
500  */
501 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
502 {
503         struct file *files[2];
504         struct coredump_params *cp = (struct coredump_params *)info->data;
505         int err = create_pipe_files(files, 0);
506         if (err)
507                 return err;
508
509         cp->file = files[1];
510
511         err = replace_fd(0, files[0], 0);
512         fput(files[0]);
513         /* and disallow core files too */
514         current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
515
516         return err;
517 }
518
519 void do_coredump(const kernel_siginfo_t *siginfo)
520 {
521         struct core_state core_state;
522         struct core_name cn;
523         struct mm_struct *mm = current->mm;
524         struct linux_binfmt * binfmt;
525         const struct cred *old_cred;
526         struct cred *cred;
527         int retval = 0;
528         int ispipe;
529         size_t *argv = NULL;
530         int argc = 0;
531         /* require nonrelative corefile path and be extra careful */
532         bool need_suid_safe = false;
533         bool core_dumped = false;
534         static atomic_t core_dump_count = ATOMIC_INIT(0);
535         struct coredump_params cprm = {
536                 .siginfo = siginfo,
537                 .limit = rlimit(RLIMIT_CORE),
538                 /*
539                  * We must use the same mm->flags while dumping core to avoid
540                  * inconsistency of bit flags, since this flag is not protected
541                  * by any locks.
542                  */
543                 .mm_flags = mm->flags,
544                 .vma_meta = NULL,
545                 .cpu = raw_smp_processor_id(),
546         };
547
548         audit_core_dumps(siginfo->si_signo);
549
550         binfmt = mm->binfmt;
551         if (!binfmt || !binfmt->core_dump)
552                 goto fail;
553         if (!__get_dumpable(cprm.mm_flags))
554                 goto fail;
555
556         cred = prepare_creds();
557         if (!cred)
558                 goto fail;
559         /*
560          * We cannot trust fsuid as being the "true" uid of the process
561          * nor do we know its entire history. We only know it was tainted
562          * so we dump it as root in mode 2, and only into a controlled
563          * environment (pipe handler or fully qualified path).
564          */
565         if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
566                 /* Setuid core dump mode */
567                 cred->fsuid = GLOBAL_ROOT_UID;  /* Dump root private */
568                 need_suid_safe = true;
569         }
570
571         retval = coredump_wait(siginfo->si_signo, &core_state);
572         if (retval < 0)
573                 goto fail_creds;
574
575         old_cred = override_creds(cred);
576
577         ispipe = format_corename(&cn, &cprm, &argv, &argc);
578
579         if (ispipe) {
580                 int argi;
581                 int dump_count;
582                 char **helper_argv;
583                 struct subprocess_info *sub_info;
584
585                 if (ispipe < 0) {
586                         printk(KERN_WARNING "format_corename failed\n");
587                         printk(KERN_WARNING "Aborting core\n");
588                         goto fail_unlock;
589                 }
590
591                 if (cprm.limit == 1) {
592                         /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
593                          *
594                          * Normally core limits are irrelevant to pipes, since
595                          * we're not writing to the file system, but we use
596                          * cprm.limit of 1 here as a special value, this is a
597                          * consistent way to catch recursive crashes.
598                          * We can still crash if the core_pattern binary sets
599                          * RLIM_CORE = !1, but it runs as root, and can do
600                          * lots of stupid things.
601                          *
602                          * Note that we use task_tgid_vnr here to grab the pid
603                          * of the process group leader.  That way we get the
604                          * right pid if a thread in a multi-threaded
605                          * core_pattern process dies.
606                          */
607                         printk(KERN_WARNING
608                                 "Process %d(%s) has RLIMIT_CORE set to 1\n",
609                                 task_tgid_vnr(current), current->comm);
610                         printk(KERN_WARNING "Aborting core\n");
611                         goto fail_unlock;
612                 }
613                 cprm.limit = RLIM_INFINITY;
614
615                 dump_count = atomic_inc_return(&core_dump_count);
616                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
617                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
618                                task_tgid_vnr(current), current->comm);
619                         printk(KERN_WARNING "Skipping core dump\n");
620                         goto fail_dropcount;
621                 }
622
623                 helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv),
624                                             GFP_KERNEL);
625                 if (!helper_argv) {
626                         printk(KERN_WARNING "%s failed to allocate memory\n",
627                                __func__);
628                         goto fail_dropcount;
629                 }
630                 for (argi = 0; argi < argc; argi++)
631                         helper_argv[argi] = cn.corename + argv[argi];
632                 helper_argv[argi] = NULL;
633
634                 retval = -ENOMEM;
635                 sub_info = call_usermodehelper_setup(helper_argv[0],
636                                                 helper_argv, NULL, GFP_KERNEL,
637                                                 umh_pipe_setup, NULL, &cprm);
638                 if (sub_info)
639                         retval = call_usermodehelper_exec(sub_info,
640                                                           UMH_WAIT_EXEC);
641
642                 kfree(helper_argv);
643                 if (retval) {
644                         printk(KERN_INFO "Core dump to |%s pipe failed\n",
645                                cn.corename);
646                         goto close_fail;
647                 }
648         } else {
649                 struct mnt_idmap *idmap;
650                 struct inode *inode;
651                 int open_flags = O_CREAT | O_WRONLY | O_NOFOLLOW |
652                                  O_LARGEFILE | O_EXCL;
653
654                 if (cprm.limit < binfmt->min_coredump)
655                         goto fail_unlock;
656
657                 if (need_suid_safe && cn.corename[0] != '/') {
658                         printk(KERN_WARNING "Pid %d(%s) can only dump core "\
659                                 "to fully qualified path!\n",
660                                 task_tgid_vnr(current), current->comm);
661                         printk(KERN_WARNING "Skipping core dump\n");
662                         goto fail_unlock;
663                 }
664
665                 /*
666                  * Unlink the file if it exists unless this is a SUID
667                  * binary - in that case, we're running around with root
668                  * privs and don't want to unlink another user's coredump.
669                  */
670                 if (!need_suid_safe) {
671                         /*
672                          * If it doesn't exist, that's fine. If there's some
673                          * other problem, we'll catch it at the filp_open().
674                          */
675                         do_unlinkat(AT_FDCWD, getname_kernel(cn.corename));
676                 }
677
678                 /*
679                  * There is a race between unlinking and creating the
680                  * file, but if that causes an EEXIST here, that's
681                  * fine - another process raced with us while creating
682                  * the corefile, and the other process won. To userspace,
683                  * what matters is that at least one of the two processes
684                  * writes its coredump successfully, not which one.
685                  */
686                 if (need_suid_safe) {
687                         /*
688                          * Using user namespaces, normal user tasks can change
689                          * their current->fs->root to point to arbitrary
690                          * directories. Since the intention of the "only dump
691                          * with a fully qualified path" rule is to control where
692                          * coredumps may be placed using root privileges,
693                          * current->fs->root must not be used. Instead, use the
694                          * root directory of init_task.
695                          */
696                         struct path root;
697
698                         task_lock(&init_task);
699                         get_fs_root(init_task.fs, &root);
700                         task_unlock(&init_task);
701                         cprm.file = file_open_root(&root, cn.corename,
702                                                    open_flags, 0600);
703                         path_put(&root);
704                 } else {
705                         cprm.file = filp_open(cn.corename, open_flags, 0600);
706                 }
707                 if (IS_ERR(cprm.file))
708                         goto fail_unlock;
709
710                 inode = file_inode(cprm.file);
711                 if (inode->i_nlink > 1)
712                         goto close_fail;
713                 if (d_unhashed(cprm.file->f_path.dentry))
714                         goto close_fail;
715                 /*
716                  * AK: actually i see no reason to not allow this for named
717                  * pipes etc, but keep the previous behaviour for now.
718                  */
719                 if (!S_ISREG(inode->i_mode))
720                         goto close_fail;
721                 /*
722                  * Don't dump core if the filesystem changed owner or mode
723                  * of the file during file creation. This is an issue when
724                  * a process dumps core while its cwd is e.g. on a vfat
725                  * filesystem.
726                  */
727                 idmap = file_mnt_idmap(cprm.file);
728                 if (!vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode),
729                                     current_fsuid())) {
730                         pr_info_ratelimited("Core dump to %s aborted: cannot preserve file owner\n",
731                                             cn.corename);
732                         goto close_fail;
733                 }
734                 if ((inode->i_mode & 0677) != 0600) {
735                         pr_info_ratelimited("Core dump to %s aborted: cannot preserve file permissions\n",
736                                             cn.corename);
737                         goto close_fail;
738                 }
739                 if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
740                         goto close_fail;
741                 if (do_truncate(idmap, cprm.file->f_path.dentry,
742                                 0, 0, cprm.file))
743                         goto close_fail;
744         }
745
746         /* get us an unshared descriptor table; almost always a no-op */
747         /* The cell spufs coredump code reads the file descriptor tables */
748         retval = unshare_files();
749         if (retval)
750                 goto close_fail;
751         if (!dump_interrupted()) {
752                 /*
753                  * umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would
754                  * have this set to NULL.
755                  */
756                 if (!cprm.file) {
757                         pr_info("Core dump to |%s disabled\n", cn.corename);
758                         goto close_fail;
759                 }
760                 if (!dump_vma_snapshot(&cprm))
761                         goto close_fail;
762
763                 file_start_write(cprm.file);
764                 core_dumped = binfmt->core_dump(&cprm);
765                 /*
766                  * Ensures that file size is big enough to contain the current
767                  * file postion. This prevents gdb from complaining about
768                  * a truncated file if the last "write" to the file was
769                  * dump_skip.
770                  */
771                 if (cprm.to_skip) {
772                         cprm.to_skip--;
773                         dump_emit(&cprm, "", 1);
774                 }
775                 file_end_write(cprm.file);
776                 free_vma_snapshot(&cprm);
777         }
778         if (ispipe && core_pipe_limit)
779                 wait_for_dump_helpers(cprm.file);
780 close_fail:
781         if (cprm.file)
782                 filp_close(cprm.file, NULL);
783 fail_dropcount:
784         if (ispipe)
785                 atomic_dec(&core_dump_count);
786 fail_unlock:
787         kfree(argv);
788         kfree(cn.corename);
789         coredump_finish(core_dumped);
790         revert_creds(old_cred);
791 fail_creds:
792         put_cred(cred);
793 fail:
794         return;
795 }
796
797 /*
798  * Core dumping helper functions.  These are the only things you should
799  * do on a core-file: use only these functions to write out all the
800  * necessary info.
801  */
802 static int __dump_emit(struct coredump_params *cprm, const void *addr, int nr)
803 {
804         struct file *file = cprm->file;
805         loff_t pos = file->f_pos;
806         ssize_t n;
807         if (cprm->written + nr > cprm->limit)
808                 return 0;
809
810
811         if (dump_interrupted())
812                 return 0;
813         n = __kernel_write(file, addr, nr, &pos);
814         if (n != nr)
815                 return 0;
816         file->f_pos = pos;
817         cprm->written += n;
818         cprm->pos += n;
819
820         return 1;
821 }
822
823 static int __dump_skip(struct coredump_params *cprm, size_t nr)
824 {
825         static char zeroes[PAGE_SIZE];
826         struct file *file = cprm->file;
827         if (file->f_mode & FMODE_LSEEK) {
828                 if (dump_interrupted() ||
829                     vfs_llseek(file, nr, SEEK_CUR) < 0)
830                         return 0;
831                 cprm->pos += nr;
832                 return 1;
833         } else {
834                 while (nr > PAGE_SIZE) {
835                         if (!__dump_emit(cprm, zeroes, PAGE_SIZE))
836                                 return 0;
837                         nr -= PAGE_SIZE;
838                 }
839                 return __dump_emit(cprm, zeroes, nr);
840         }
841 }
842
843 int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
844 {
845         if (cprm->to_skip) {
846                 if (!__dump_skip(cprm, cprm->to_skip))
847                         return 0;
848                 cprm->to_skip = 0;
849         }
850         return __dump_emit(cprm, addr, nr);
851 }
852 EXPORT_SYMBOL(dump_emit);
853
854 void dump_skip_to(struct coredump_params *cprm, unsigned long pos)
855 {
856         cprm->to_skip = pos - cprm->pos;
857 }
858 EXPORT_SYMBOL(dump_skip_to);
859
860 void dump_skip(struct coredump_params *cprm, size_t nr)
861 {
862         cprm->to_skip += nr;
863 }
864 EXPORT_SYMBOL(dump_skip);
865
866 #ifdef CONFIG_ELF_CORE
867 static int dump_emit_page(struct coredump_params *cprm, struct page *page)
868 {
869         struct bio_vec bvec;
870         struct iov_iter iter;
871         struct file *file = cprm->file;
872         loff_t pos;
873         ssize_t n;
874
875         if (cprm->to_skip) {
876                 if (!__dump_skip(cprm, cprm->to_skip))
877                         return 0;
878                 cprm->to_skip = 0;
879         }
880         if (cprm->written + PAGE_SIZE > cprm->limit)
881                 return 0;
882         if (dump_interrupted())
883                 return 0;
884         pos = file->f_pos;
885         bvec_set_page(&bvec, page, PAGE_SIZE, 0);
886         iov_iter_bvec(&iter, ITER_SOURCE, &bvec, 1, PAGE_SIZE);
887         iov_iter_set_copy_mc(&iter);
888         n = __kernel_write_iter(cprm->file, &iter, &pos);
889         if (n != PAGE_SIZE)
890                 return 0;
891         file->f_pos = pos;
892         cprm->written += PAGE_SIZE;
893         cprm->pos += PAGE_SIZE;
894
895         return 1;
896 }
897
898 int dump_user_range(struct coredump_params *cprm, unsigned long start,
899                     unsigned long len)
900 {
901         unsigned long addr;
902
903         for (addr = start; addr < start + len; addr += PAGE_SIZE) {
904                 struct page *page;
905
906                 /*
907                  * To avoid having to allocate page tables for virtual address
908                  * ranges that have never been used yet, and also to make it
909                  * easy to generate sparse core files, use a helper that returns
910                  * NULL when encountering an empty page table entry that would
911                  * otherwise have been filled with the zero page.
912                  */
913                 page = get_dump_page(addr);
914                 if (page) {
915                         int stop = !dump_emit_page(cprm, page);
916                         put_page(page);
917                         if (stop)
918                                 return 0;
919                 } else {
920                         dump_skip(cprm, PAGE_SIZE);
921                 }
922         }
923         return 1;
924 }
925 #endif
926
927 int dump_align(struct coredump_params *cprm, int align)
928 {
929         unsigned mod = (cprm->pos + cprm->to_skip) & (align - 1);
930         if (align & (align - 1))
931                 return 0;
932         if (mod)
933                 cprm->to_skip += align - mod;
934         return 1;
935 }
936 EXPORT_SYMBOL(dump_align);
937
938 #ifdef CONFIG_SYSCTL
939
940 void validate_coredump_safety(void)
941 {
942         if (suid_dumpable == SUID_DUMP_ROOT &&
943             core_pattern[0] != '/' && core_pattern[0] != '|') {
944                 pr_warn(
945 "Unsafe core_pattern used with fs.suid_dumpable=2.\n"
946 "Pipe handler or fully qualified core dump path required.\n"
947 "Set kernel.core_pattern before fs.suid_dumpable.\n"
948                 );
949         }
950 }
951
952 static int proc_dostring_coredump(struct ctl_table *table, int write,
953                   void *buffer, size_t *lenp, loff_t *ppos)
954 {
955         int error = proc_dostring(table, write, buffer, lenp, ppos);
956
957         if (!error)
958                 validate_coredump_safety();
959         return error;
960 }
961
962 static struct ctl_table coredump_sysctls[] = {
963         {
964                 .procname       = "core_uses_pid",
965                 .data           = &core_uses_pid,
966                 .maxlen         = sizeof(int),
967                 .mode           = 0644,
968                 .proc_handler   = proc_dointvec,
969         },
970         {
971                 .procname       = "core_pattern",
972                 .data           = core_pattern,
973                 .maxlen         = CORENAME_MAX_SIZE,
974                 .mode           = 0644,
975                 .proc_handler   = proc_dostring_coredump,
976         },
977         {
978                 .procname       = "core_pipe_limit",
979                 .data           = &core_pipe_limit,
980                 .maxlen         = sizeof(unsigned int),
981                 .mode           = 0644,
982                 .proc_handler   = proc_dointvec,
983         },
984         { }
985 };
986
987 static int __init init_fs_coredump_sysctls(void)
988 {
989         register_sysctl_init("kernel", coredump_sysctls);
990         return 0;
991 }
992 fs_initcall(init_fs_coredump_sysctls);
993 #endif /* CONFIG_SYSCTL */
994
995 /*
996  * The purpose of always_dump_vma() is to make sure that special kernel mappings
997  * that are useful for post-mortem analysis are included in every core dump.
998  * In that way we ensure that the core dump is fully interpretable later
999  * without matching up the same kernel and hardware config to see what PC values
1000  * meant. These special mappings include - vDSO, vsyscall, and other
1001  * architecture specific mappings
1002  */
1003 static bool always_dump_vma(struct vm_area_struct *vma)
1004 {
1005         /* Any vsyscall mappings? */
1006         if (vma == get_gate_vma(vma->vm_mm))
1007                 return true;
1008
1009         /*
1010          * Assume that all vmas with a .name op should always be dumped.
1011          * If this changes, a new vm_ops field can easily be added.
1012          */
1013         if (vma->vm_ops && vma->vm_ops->name && vma->vm_ops->name(vma))
1014                 return true;
1015
1016         /*
1017          * arch_vma_name() returns non-NULL for special architecture mappings,
1018          * such as vDSO sections.
1019          */
1020         if (arch_vma_name(vma))
1021                 return true;
1022
1023         return false;
1024 }
1025
1026 #define DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER 1
1027
1028 /*
1029  * Decide how much of @vma's contents should be included in a core dump.
1030  */
1031 static unsigned long vma_dump_size(struct vm_area_struct *vma,
1032                                    unsigned long mm_flags)
1033 {
1034 #define FILTER(type)    (mm_flags & (1UL << MMF_DUMP_##type))
1035
1036         /* always dump the vdso and vsyscall sections */
1037         if (always_dump_vma(vma))
1038                 goto whole;
1039
1040         if (vma->vm_flags & VM_DONTDUMP)
1041                 return 0;
1042
1043         /* support for DAX */
1044         if (vma_is_dax(vma)) {
1045                 if ((vma->vm_flags & VM_SHARED) && FILTER(DAX_SHARED))
1046                         goto whole;
1047                 if (!(vma->vm_flags & VM_SHARED) && FILTER(DAX_PRIVATE))
1048                         goto whole;
1049                 return 0;
1050         }
1051
1052         /* Hugetlb memory check */
1053         if (is_vm_hugetlb_page(vma)) {
1054                 if ((vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_SHARED))
1055                         goto whole;
1056                 if (!(vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_PRIVATE))
1057                         goto whole;
1058                 return 0;
1059         }
1060
1061         /* Do not dump I/O mapped devices or special mappings */
1062         if (vma->vm_flags & VM_IO)
1063                 return 0;
1064
1065         /* By default, dump shared memory if mapped from an anonymous file. */
1066         if (vma->vm_flags & VM_SHARED) {
1067                 if (file_inode(vma->vm_file)->i_nlink == 0 ?
1068                     FILTER(ANON_SHARED) : FILTER(MAPPED_SHARED))
1069                         goto whole;
1070                 return 0;
1071         }
1072
1073         /* Dump segments that have been written to.  */
1074         if ((!IS_ENABLED(CONFIG_MMU) || vma->anon_vma) && FILTER(ANON_PRIVATE))
1075                 goto whole;
1076         if (vma->vm_file == NULL)
1077                 return 0;
1078
1079         if (FILTER(MAPPED_PRIVATE))
1080                 goto whole;
1081
1082         /*
1083          * If this is the beginning of an executable file mapping,
1084          * dump the first page to aid in determining what was mapped here.
1085          */
1086         if (FILTER(ELF_HEADERS) &&
1087             vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ)) {
1088                 if ((READ_ONCE(file_inode(vma->vm_file)->i_mode) & 0111) != 0)
1089                         return PAGE_SIZE;
1090
1091                 /*
1092                  * ELF libraries aren't always executable.
1093                  * We'll want to check whether the mapping starts with the ELF
1094                  * magic, but not now - we're holding the mmap lock,
1095                  * so copy_from_user() doesn't work here.
1096                  * Use a placeholder instead, and fix it up later in
1097                  * dump_vma_snapshot().
1098                  */
1099                 return DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER;
1100         }
1101
1102 #undef  FILTER
1103
1104         return 0;
1105
1106 whole:
1107         return vma->vm_end - vma->vm_start;
1108 }
1109
1110 /*
1111  * Helper function for iterating across a vma list.  It ensures that the caller
1112  * will visit `gate_vma' prior to terminating the search.
1113  */
1114 static struct vm_area_struct *coredump_next_vma(struct vma_iterator *vmi,
1115                                        struct vm_area_struct *vma,
1116                                        struct vm_area_struct *gate_vma)
1117 {
1118         if (gate_vma && (vma == gate_vma))
1119                 return NULL;
1120
1121         vma = vma_next(vmi);
1122         if (vma)
1123                 return vma;
1124         return gate_vma;
1125 }
1126
1127 static void free_vma_snapshot(struct coredump_params *cprm)
1128 {
1129         if (cprm->vma_meta) {
1130                 int i;
1131                 for (i = 0; i < cprm->vma_count; i++) {
1132                         struct file *file = cprm->vma_meta[i].file;
1133                         if (file)
1134                                 fput(file);
1135                 }
1136                 kvfree(cprm->vma_meta);
1137                 cprm->vma_meta = NULL;
1138         }
1139 }
1140
1141 /*
1142  * Under the mmap_lock, take a snapshot of relevant information about the task's
1143  * VMAs.
1144  */
1145 static bool dump_vma_snapshot(struct coredump_params *cprm)
1146 {
1147         struct vm_area_struct *gate_vma, *vma = NULL;
1148         struct mm_struct *mm = current->mm;
1149         VMA_ITERATOR(vmi, mm, 0);
1150         int i = 0;
1151
1152         /*
1153          * Once the stack expansion code is fixed to not change VMA bounds
1154          * under mmap_lock in read mode, this can be changed to take the
1155          * mmap_lock in read mode.
1156          */
1157         if (mmap_write_lock_killable(mm))
1158                 return false;
1159
1160         cprm->vma_data_size = 0;
1161         gate_vma = get_gate_vma(mm);
1162         cprm->vma_count = mm->map_count + (gate_vma ? 1 : 0);
1163
1164         cprm->vma_meta = kvmalloc_array(cprm->vma_count, sizeof(*cprm->vma_meta), GFP_KERNEL);
1165         if (!cprm->vma_meta) {
1166                 mmap_write_unlock(mm);
1167                 return false;
1168         }
1169
1170         while ((vma = coredump_next_vma(&vmi, vma, gate_vma)) != NULL) {
1171                 struct core_vma_metadata *m = cprm->vma_meta + i;
1172
1173                 m->start = vma->vm_start;
1174                 m->end = vma->vm_end;
1175                 m->flags = vma->vm_flags;
1176                 m->dump_size = vma_dump_size(vma, cprm->mm_flags);
1177                 m->pgoff = vma->vm_pgoff;
1178                 m->file = vma->vm_file;
1179                 if (m->file)
1180                         get_file(m->file);
1181                 i++;
1182         }
1183
1184         mmap_write_unlock(mm);
1185
1186         for (i = 0; i < cprm->vma_count; i++) {
1187                 struct core_vma_metadata *m = cprm->vma_meta + i;
1188
1189                 if (m->dump_size == DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER) {
1190                         char elfmag[SELFMAG];
1191
1192                         if (copy_from_user(elfmag, (void __user *)m->start, SELFMAG) ||
1193                                         memcmp(elfmag, ELFMAG, SELFMAG) != 0) {
1194                                 m->dump_size = 0;
1195                         } else {
1196                                 m->dump_size = PAGE_SIZE;
1197                         }
1198                 }
1199
1200                 cprm->vma_data_size += m->dump_size;
1201         }
1202
1203         return true;
1204 }