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>
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>
41 #include <linux/path.h>
42 #include <linux/timekeeping.h>
43 #include <linux/sysctl.h>
44 #include <linux/elf.h>
46 #include <linux/uaccess.h>
47 #include <asm/mmu_context.h>
51 #include <trace/events/task.h>
54 #include <trace/events/sched.h>
56 static bool dump_vma_snapshot(struct coredump_params
*cprm
);
57 static void free_vma_snapshot(struct coredump_params
*cprm
);
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
;
69 static int expand_corename(struct core_name
*cn
, int size
)
71 char *corename
= krealloc(cn
->corename
, size
, GFP_KERNEL
);
76 if (size
> core_name_size
) /* racy but harmless */
77 core_name_size
= size
;
79 cn
->size
= ksize(corename
);
80 cn
->corename
= corename
;
84 static __printf(2, 0) int cn_vprintf(struct core_name
*cn
, const char *fmt
,
91 free
= cn
->size
- cn
->used
;
93 va_copy(arg_copy
, arg
);
94 need
= vsnprintf(cn
->corename
+ cn
->used
, free
, fmt
, arg_copy
);
102 if (!expand_corename(cn
, cn
->size
+ need
- free
+ 1))
108 static __printf(2, 3) int cn_printf(struct core_name
*cn
, const char *fmt
, ...)
114 ret
= cn_vprintf(cn
, fmt
, arg
);
120 static __printf(2, 3)
121 int cn_esc_printf(struct core_name
*cn
, const char *fmt
, ...)
128 ret
= cn_vprintf(cn
, fmt
, arg
);
133 * Ensure that this coredump name component can't cause the
134 * resulting corefile path to consist of a ".." or ".".
136 if ((cn
->used
- cur
== 1 && cn
->corename
[cur
] == '.') ||
137 (cn
->used
- cur
== 2 && cn
->corename
[cur
] == '.'
138 && cn
->corename
[cur
+1] == '.'))
139 cn
->corename
[cur
] = '!';
142 * Empty names are fishy and could be used to create a "//" in a
143 * corefile name, causing the coredump to happen one directory
144 * level too high. Enforce that all components of the core
145 * pattern are at least one character long.
148 ret
= cn_printf(cn
, "!");
151 for (; cur
< cn
->used
; ++cur
) {
152 if (cn
->corename
[cur
] == '/')
153 cn
->corename
[cur
] = '!';
158 static int cn_print_exe_file(struct core_name
*cn
, bool name_only
)
160 struct file
*exe_file
;
161 char *pathbuf
, *path
, *ptr
;
164 exe_file
= get_mm_exe_file(current
->mm
);
166 return cn_esc_printf(cn
, "%s (path unknown)", current
->comm
);
168 pathbuf
= kmalloc(PATH_MAX
, GFP_KERNEL
);
174 path
= file_path(exe_file
, pathbuf
, PATH_MAX
);
181 ptr
= strrchr(path
, '/');
185 ret
= cn_esc_printf(cn
, "%s", path
);
194 /* format_corename will inspect the pattern parameter, and output a
195 * name into corename, which must have space for at least
196 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
198 static int format_corename(struct core_name
*cn
, struct coredump_params
*cprm
,
199 size_t **argv
, int *argc
)
201 const struct cred
*cred
= current_cred();
202 const char *pat_ptr
= core_pattern
;
203 int ispipe
= (*pat_ptr
== '|');
204 bool was_space
= false;
205 int pid_in_pattern
= 0;
210 if (expand_corename(cn
, core_name_size
))
212 cn
->corename
[0] = '\0';
215 int argvs
= sizeof(core_pattern
) / 2;
216 (*argv
) = kmalloc_array(argvs
, sizeof(**argv
), GFP_KERNEL
);
219 (*argv
)[(*argc
)++] = 0;
225 /* Repeat as long as we have more pattern to process and more output
229 * Split on spaces before doing template expansion so that
230 * %e and %E don't get split if they have spaces in them
233 if (isspace(*pat_ptr
)) {
238 } else if (was_space
) {
240 err
= cn_printf(cn
, "%c", '\0');
243 (*argv
)[(*argc
)++] = cn
->used
;
246 if (*pat_ptr
!= '%') {
247 err
= cn_printf(cn
, "%c", *pat_ptr
++);
249 switch (*++pat_ptr
) {
250 /* single % at the end, drop that */
253 /* Double percent, output one percent */
255 err
= cn_printf(cn
, "%c", '%');
260 err
= cn_printf(cn
, "%d",
261 task_tgid_vnr(current
));
265 err
= cn_printf(cn
, "%d",
266 task_tgid_nr(current
));
269 err
= cn_printf(cn
, "%d",
270 task_pid_vnr(current
));
273 err
= cn_printf(cn
, "%d",
274 task_pid_nr(current
));
278 err
= cn_printf(cn
, "%u",
279 from_kuid(&init_user_ns
,
284 err
= cn_printf(cn
, "%u",
285 from_kgid(&init_user_ns
,
289 err
= cn_printf(cn
, "%d",
290 __get_dumpable(cprm
->mm_flags
));
292 /* signal that caused the coredump */
294 err
= cn_printf(cn
, "%d",
295 cprm
->siginfo
->si_signo
);
297 /* UNIX time of coredump */
301 time
= ktime_get_real_seconds();
302 err
= cn_printf(cn
, "%lld", time
);
308 err
= cn_esc_printf(cn
, "%s",
309 utsname()->nodename
);
312 /* executable, could be changed by prctl PR_SET_NAME etc */
314 err
= cn_esc_printf(cn
, "%s", current
->comm
);
316 /* file name of executable */
318 err
= cn_print_exe_file(cn
, true);
321 err
= cn_print_exe_file(cn
, false);
323 /* core limit size */
325 err
= cn_printf(cn
, "%lu",
326 rlimit(RLIMIT_CORE
));
339 /* Backward compatibility with core_uses_pid:
341 * If core_pattern does not include a %p (as is the default)
342 * and core_uses_pid is set, then .%pid will be appended to
343 * the filename. Do not do this for piped commands. */
344 if (!ispipe
&& !pid_in_pattern
&& core_uses_pid
) {
345 err
= cn_printf(cn
, ".%d", task_tgid_vnr(current
));
352 static int zap_process(struct task_struct
*start
, int exit_code
)
354 struct task_struct
*t
;
357 /* ignore all signals except SIGKILL, see prepare_signal() */
358 start
->signal
->flags
= SIGNAL_GROUP_EXIT
;
359 start
->signal
->group_exit_code
= exit_code
;
360 start
->signal
->group_stop_count
= 0;
362 for_each_thread(start
, t
) {
363 task_clear_jobctl_pending(t
, JOBCTL_PENDING_MASK
);
364 if (t
!= current
&& !(t
->flags
& PF_POSTCOREDUMP
)) {
365 sigaddset(&t
->pending
.signal
, SIGKILL
);
366 signal_wake_up(t
, 1);
374 static int zap_threads(struct task_struct
*tsk
,
375 struct core_state
*core_state
, int exit_code
)
377 struct signal_struct
*signal
= tsk
->signal
;
380 spin_lock_irq(&tsk
->sighand
->siglock
);
381 if (!(signal
->flags
& SIGNAL_GROUP_EXIT
) && !signal
->group_exec_task
) {
382 signal
->core_state
= core_state
;
383 nr
= zap_process(tsk
, exit_code
);
384 clear_tsk_thread_flag(tsk
, TIF_SIGPENDING
);
385 tsk
->flags
|= PF_DUMPCORE
;
386 atomic_set(&core_state
->nr_threads
, nr
);
388 spin_unlock_irq(&tsk
->sighand
->siglock
);
392 static int coredump_wait(int exit_code
, struct core_state
*core_state
)
394 struct task_struct
*tsk
= current
;
395 int core_waiters
= -EBUSY
;
397 init_completion(&core_state
->startup
);
398 core_state
->dumper
.task
= tsk
;
399 core_state
->dumper
.next
= NULL
;
401 core_waiters
= zap_threads(tsk
, core_state
, exit_code
);
402 if (core_waiters
> 0) {
403 struct core_thread
*ptr
;
405 freezer_do_not_count();
406 wait_for_completion(&core_state
->startup
);
409 * Wait for all the threads to become inactive, so that
410 * all the thread context (extended register state, like
411 * fpu etc) gets copied to the memory.
413 ptr
= core_state
->dumper
.next
;
414 while (ptr
!= NULL
) {
415 wait_task_inactive(ptr
->task
, 0);
423 static void coredump_finish(bool core_dumped
)
425 struct core_thread
*curr
, *next
;
426 struct task_struct
*task
;
428 spin_lock_irq(¤t
->sighand
->siglock
);
429 if (core_dumped
&& !__fatal_signal_pending(current
))
430 current
->signal
->group_exit_code
|= 0x80;
431 next
= current
->signal
->core_state
->dumper
.next
;
432 current
->signal
->core_state
= NULL
;
433 spin_unlock_irq(¤t
->sighand
->siglock
);
435 while ((curr
= next
) != NULL
) {
439 * see coredump_task_exit(), curr->task must not see
440 * ->task == NULL before we read ->next.
444 wake_up_process(task
);
448 static bool dump_interrupted(void)
451 * SIGKILL or freezing() interrupt the coredumping. Perhaps we
452 * can do try_to_freeze() and check __fatal_signal_pending(),
453 * but then we need to teach dump_write() to restart and clear
456 return fatal_signal_pending(current
) || freezing(current
);
459 static void wait_for_dump_helpers(struct file
*file
)
461 struct pipe_inode_info
*pipe
= file
->private_data
;
466 wake_up_interruptible_sync(&pipe
->rd_wait
);
467 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
471 * We actually want wait_event_freezable() but then we need
472 * to clear TIF_SIGPENDING and improve dump_interrupted().
474 wait_event_interruptible(pipe
->rd_wait
, pipe
->readers
== 1);
484 * helper function to customize the process used
485 * to collect the core in userspace. Specifically
486 * it sets up a pipe and installs it as fd 0 (stdin)
487 * for the process. Returns 0 on success, or
488 * PTR_ERR on failure.
489 * Note that it also sets the core limit to 1. This
490 * is a special value that we use to trap recursive
493 static int umh_pipe_setup(struct subprocess_info
*info
, struct cred
*new)
495 struct file
*files
[2];
496 struct coredump_params
*cp
= (struct coredump_params
*)info
->data
;
497 int err
= create_pipe_files(files
, 0);
503 err
= replace_fd(0, files
[0], 0);
505 /* and disallow core files too */
506 current
->signal
->rlim
[RLIMIT_CORE
] = (struct rlimit
){1, 1};
511 void do_coredump(const kernel_siginfo_t
*siginfo
)
513 struct core_state core_state
;
515 struct mm_struct
*mm
= current
->mm
;
516 struct linux_binfmt
* binfmt
;
517 const struct cred
*old_cred
;
523 /* require nonrelative corefile path and be extra careful */
524 bool need_suid_safe
= false;
525 bool core_dumped
= false;
526 static atomic_t core_dump_count
= ATOMIC_INIT(0);
527 struct coredump_params cprm
= {
529 .regs
= signal_pt_regs(),
530 .limit
= rlimit(RLIMIT_CORE
),
532 * We must use the same mm->flags while dumping core to avoid
533 * inconsistency of bit flags, since this flag is not protected
536 .mm_flags
= mm
->flags
,
540 audit_core_dumps(siginfo
->si_signo
);
543 if (!binfmt
|| !binfmt
->core_dump
)
545 if (!__get_dumpable(cprm
.mm_flags
))
548 cred
= prepare_creds();
552 * We cannot trust fsuid as being the "true" uid of the process
553 * nor do we know its entire history. We only know it was tainted
554 * so we dump it as root in mode 2, and only into a controlled
555 * environment (pipe handler or fully qualified path).
557 if (__get_dumpable(cprm
.mm_flags
) == SUID_DUMP_ROOT
) {
558 /* Setuid core dump mode */
559 cred
->fsuid
= GLOBAL_ROOT_UID
; /* Dump root private */
560 need_suid_safe
= true;
563 retval
= coredump_wait(siginfo
->si_signo
, &core_state
);
567 old_cred
= override_creds(cred
);
569 ispipe
= format_corename(&cn
, &cprm
, &argv
, &argc
);
575 struct subprocess_info
*sub_info
;
578 printk(KERN_WARNING
"format_corename failed\n");
579 printk(KERN_WARNING
"Aborting core\n");
583 if (cprm
.limit
== 1) {
584 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
586 * Normally core limits are irrelevant to pipes, since
587 * we're not writing to the file system, but we use
588 * cprm.limit of 1 here as a special value, this is a
589 * consistent way to catch recursive crashes.
590 * We can still crash if the core_pattern binary sets
591 * RLIM_CORE = !1, but it runs as root, and can do
592 * lots of stupid things.
594 * Note that we use task_tgid_vnr here to grab the pid
595 * of the process group leader. That way we get the
596 * right pid if a thread in a multi-threaded
597 * core_pattern process dies.
600 "Process %d(%s) has RLIMIT_CORE set to 1\n",
601 task_tgid_vnr(current
), current
->comm
);
602 printk(KERN_WARNING
"Aborting core\n");
605 cprm
.limit
= RLIM_INFINITY
;
607 dump_count
= atomic_inc_return(&core_dump_count
);
608 if (core_pipe_limit
&& (core_pipe_limit
< dump_count
)) {
609 printk(KERN_WARNING
"Pid %d(%s) over core_pipe_limit\n",
610 task_tgid_vnr(current
), current
->comm
);
611 printk(KERN_WARNING
"Skipping core dump\n");
615 helper_argv
= kmalloc_array(argc
+ 1, sizeof(*helper_argv
),
618 printk(KERN_WARNING
"%s failed to allocate memory\n",
622 for (argi
= 0; argi
< argc
; argi
++)
623 helper_argv
[argi
] = cn
.corename
+ argv
[argi
];
624 helper_argv
[argi
] = NULL
;
627 sub_info
= call_usermodehelper_setup(helper_argv
[0],
628 helper_argv
, NULL
, GFP_KERNEL
,
629 umh_pipe_setup
, NULL
, &cprm
);
631 retval
= call_usermodehelper_exec(sub_info
,
636 printk(KERN_INFO
"Core dump to |%s pipe failed\n",
641 struct user_namespace
*mnt_userns
;
643 int open_flags
= O_CREAT
| O_RDWR
| O_NOFOLLOW
|
644 O_LARGEFILE
| O_EXCL
;
646 if (cprm
.limit
< binfmt
->min_coredump
)
649 if (need_suid_safe
&& cn
.corename
[0] != '/') {
650 printk(KERN_WARNING
"Pid %d(%s) can only dump core "\
651 "to fully qualified path!\n",
652 task_tgid_vnr(current
), current
->comm
);
653 printk(KERN_WARNING
"Skipping core dump\n");
658 * Unlink the file if it exists unless this is a SUID
659 * binary - in that case, we're running around with root
660 * privs and don't want to unlink another user's coredump.
662 if (!need_suid_safe
) {
664 * If it doesn't exist, that's fine. If there's some
665 * other problem, we'll catch it at the filp_open().
667 do_unlinkat(AT_FDCWD
, getname_kernel(cn
.corename
));
671 * There is a race between unlinking and creating the
672 * file, but if that causes an EEXIST here, that's
673 * fine - another process raced with us while creating
674 * the corefile, and the other process won. To userspace,
675 * what matters is that at least one of the two processes
676 * writes its coredump successfully, not which one.
678 if (need_suid_safe
) {
680 * Using user namespaces, normal user tasks can change
681 * their current->fs->root to point to arbitrary
682 * directories. Since the intention of the "only dump
683 * with a fully qualified path" rule is to control where
684 * coredumps may be placed using root privileges,
685 * current->fs->root must not be used. Instead, use the
686 * root directory of init_task.
690 task_lock(&init_task
);
691 get_fs_root(init_task
.fs
, &root
);
692 task_unlock(&init_task
);
693 cprm
.file
= file_open_root(&root
, cn
.corename
,
697 cprm
.file
= filp_open(cn
.corename
, open_flags
, 0600);
699 if (IS_ERR(cprm
.file
))
702 inode
= file_inode(cprm
.file
);
703 if (inode
->i_nlink
> 1)
705 if (d_unhashed(cprm
.file
->f_path
.dentry
))
708 * AK: actually i see no reason to not allow this for named
709 * pipes etc, but keep the previous behaviour for now.
711 if (!S_ISREG(inode
->i_mode
))
714 * Don't dump core if the filesystem changed owner or mode
715 * of the file during file creation. This is an issue when
716 * a process dumps core while its cwd is e.g. on a vfat
719 mnt_userns
= file_mnt_user_ns(cprm
.file
);
720 if (!uid_eq(i_uid_into_mnt(mnt_userns
, inode
),
722 pr_info_ratelimited("Core dump to %s aborted: cannot preserve file owner\n",
726 if ((inode
->i_mode
& 0677) != 0600) {
727 pr_info_ratelimited("Core dump to %s aborted: cannot preserve file permissions\n",
731 if (!(cprm
.file
->f_mode
& FMODE_CAN_WRITE
))
733 if (do_truncate(mnt_userns
, cprm
.file
->f_path
.dentry
,
738 /* get us an unshared descriptor table; almost always a no-op */
739 /* The cell spufs coredump code reads the file descriptor tables */
740 retval
= unshare_files();
743 if (!dump_interrupted()) {
745 * umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would
746 * have this set to NULL.
749 pr_info("Core dump to |%s disabled\n", cn
.corename
);
752 if (!dump_vma_snapshot(&cprm
))
755 file_start_write(cprm
.file
);
756 core_dumped
= binfmt
->core_dump(&cprm
);
758 * Ensures that file size is big enough to contain the current
759 * file postion. This prevents gdb from complaining about
760 * a truncated file if the last "write" to the file was
765 dump_emit(&cprm
, "", 1);
767 file_end_write(cprm
.file
);
768 free_vma_snapshot(&cprm
);
770 if (ispipe
&& core_pipe_limit
)
771 wait_for_dump_helpers(cprm
.file
);
774 filp_close(cprm
.file
, NULL
);
777 atomic_dec(&core_dump_count
);
781 coredump_finish(core_dumped
);
782 revert_creds(old_cred
);
790 * Core dumping helper functions. These are the only things you should
791 * do on a core-file: use only these functions to write out all the
794 static int __dump_emit(struct coredump_params
*cprm
, const void *addr
, int nr
)
796 struct file
*file
= cprm
->file
;
797 loff_t pos
= file
->f_pos
;
799 if (cprm
->written
+ nr
> cprm
->limit
)
803 if (dump_interrupted())
805 n
= __kernel_write(file
, addr
, nr
, &pos
);
815 static int __dump_skip(struct coredump_params
*cprm
, size_t nr
)
817 static char zeroes
[PAGE_SIZE
];
818 struct file
*file
= cprm
->file
;
819 if (file
->f_op
->llseek
&& file
->f_op
->llseek
!= no_llseek
) {
820 if (dump_interrupted() ||
821 file
->f_op
->llseek(file
, nr
, SEEK_CUR
) < 0)
826 while (nr
> PAGE_SIZE
) {
827 if (!__dump_emit(cprm
, zeroes
, PAGE_SIZE
))
831 return __dump_emit(cprm
, zeroes
, nr
);
835 int dump_emit(struct coredump_params
*cprm
, const void *addr
, int nr
)
838 if (!__dump_skip(cprm
, cprm
->to_skip
))
842 return __dump_emit(cprm
, addr
, nr
);
844 EXPORT_SYMBOL(dump_emit
);
846 void dump_skip_to(struct coredump_params
*cprm
, unsigned long pos
)
848 cprm
->to_skip
= pos
- cprm
->pos
;
850 EXPORT_SYMBOL(dump_skip_to
);
852 void dump_skip(struct coredump_params
*cprm
, size_t nr
)
856 EXPORT_SYMBOL(dump_skip
);
858 #ifdef CONFIG_ELF_CORE
859 int dump_user_range(struct coredump_params
*cprm
, unsigned long start
,
864 for (addr
= start
; addr
< start
+ len
; addr
+= PAGE_SIZE
) {
869 * To avoid having to allocate page tables for virtual address
870 * ranges that have never been used yet, and also to make it
871 * easy to generate sparse core files, use a helper that returns
872 * NULL when encountering an empty page table entry that would
873 * otherwise have been filled with the zero page.
875 page
= get_dump_page(addr
);
877 void *kaddr
= kmap_local_page(page
);
879 stop
= !dump_emit(cprm
, kaddr
, PAGE_SIZE
);
885 dump_skip(cprm
, PAGE_SIZE
);
892 int dump_align(struct coredump_params
*cprm
, int align
)
894 unsigned mod
= (cprm
->pos
+ cprm
->to_skip
) & (align
- 1);
895 if (align
& (align
- 1))
898 cprm
->to_skip
+= align
- mod
;
901 EXPORT_SYMBOL(dump_align
);
905 void validate_coredump_safety(void)
907 if (suid_dumpable
== SUID_DUMP_ROOT
&&
908 core_pattern
[0] != '/' && core_pattern
[0] != '|') {
910 "Unsafe core_pattern used with fs.suid_dumpable=2.\n"
911 "Pipe handler or fully qualified core dump path required.\n"
912 "Set kernel.core_pattern before fs.suid_dumpable.\n"
917 static int proc_dostring_coredump(struct ctl_table
*table
, int write
,
918 void *buffer
, size_t *lenp
, loff_t
*ppos
)
920 int error
= proc_dostring(table
, write
, buffer
, lenp
, ppos
);
923 validate_coredump_safety();
927 static struct ctl_table coredump_sysctls
[] = {
929 .procname
= "core_uses_pid",
930 .data
= &core_uses_pid
,
931 .maxlen
= sizeof(int),
933 .proc_handler
= proc_dointvec
,
936 .procname
= "core_pattern",
937 .data
= core_pattern
,
938 .maxlen
= CORENAME_MAX_SIZE
,
940 .proc_handler
= proc_dostring_coredump
,
943 .procname
= "core_pipe_limit",
944 .data
= &core_pipe_limit
,
945 .maxlen
= sizeof(unsigned int),
947 .proc_handler
= proc_dointvec
,
952 static int __init
init_fs_coredump_sysctls(void)
954 register_sysctl_init("kernel", coredump_sysctls
);
957 fs_initcall(init_fs_coredump_sysctls
);
958 #endif /* CONFIG_SYSCTL */
961 * The purpose of always_dump_vma() is to make sure that special kernel mappings
962 * that are useful for post-mortem analysis are included in every core dump.
963 * In that way we ensure that the core dump is fully interpretable later
964 * without matching up the same kernel and hardware config to see what PC values
965 * meant. These special mappings include - vDSO, vsyscall, and other
966 * architecture specific mappings
968 static bool always_dump_vma(struct vm_area_struct
*vma
)
970 /* Any vsyscall mappings? */
971 if (vma
== get_gate_vma(vma
->vm_mm
))
975 * Assume that all vmas with a .name op should always be dumped.
976 * If this changes, a new vm_ops field can easily be added.
978 if (vma
->vm_ops
&& vma
->vm_ops
->name
&& vma
->vm_ops
->name(vma
))
982 * arch_vma_name() returns non-NULL for special architecture mappings,
983 * such as vDSO sections.
985 if (arch_vma_name(vma
))
991 #define DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER 1
994 * Decide how much of @vma's contents should be included in a core dump.
996 static unsigned long vma_dump_size(struct vm_area_struct
*vma
,
997 unsigned long mm_flags
)
999 #define FILTER(type) (mm_flags & (1UL << MMF_DUMP_##type))
1001 /* always dump the vdso and vsyscall sections */
1002 if (always_dump_vma(vma
))
1005 if (vma
->vm_flags
& VM_DONTDUMP
)
1008 /* support for DAX */
1009 if (vma_is_dax(vma
)) {
1010 if ((vma
->vm_flags
& VM_SHARED
) && FILTER(DAX_SHARED
))
1012 if (!(vma
->vm_flags
& VM_SHARED
) && FILTER(DAX_PRIVATE
))
1017 /* Hugetlb memory check */
1018 if (is_vm_hugetlb_page(vma
)) {
1019 if ((vma
->vm_flags
& VM_SHARED
) && FILTER(HUGETLB_SHARED
))
1021 if (!(vma
->vm_flags
& VM_SHARED
) && FILTER(HUGETLB_PRIVATE
))
1026 /* Do not dump I/O mapped devices or special mappings */
1027 if (vma
->vm_flags
& VM_IO
)
1030 /* By default, dump shared memory if mapped from an anonymous file. */
1031 if (vma
->vm_flags
& VM_SHARED
) {
1032 if (file_inode(vma
->vm_file
)->i_nlink
== 0 ?
1033 FILTER(ANON_SHARED
) : FILTER(MAPPED_SHARED
))
1038 /* Dump segments that have been written to. */
1039 if ((!IS_ENABLED(CONFIG_MMU
) || vma
->anon_vma
) && FILTER(ANON_PRIVATE
))
1041 if (vma
->vm_file
== NULL
)
1044 if (FILTER(MAPPED_PRIVATE
))
1048 * If this is the beginning of an executable file mapping,
1049 * dump the first page to aid in determining what was mapped here.
1051 if (FILTER(ELF_HEADERS
) &&
1052 vma
->vm_pgoff
== 0 && (vma
->vm_flags
& VM_READ
)) {
1053 if ((READ_ONCE(file_inode(vma
->vm_file
)->i_mode
) & 0111) != 0)
1057 * ELF libraries aren't always executable.
1058 * We'll want to check whether the mapping starts with the ELF
1059 * magic, but not now - we're holding the mmap lock,
1060 * so copy_from_user() doesn't work here.
1061 * Use a placeholder instead, and fix it up later in
1062 * dump_vma_snapshot().
1064 return DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER
;
1072 return vma
->vm_end
- vma
->vm_start
;
1075 static struct vm_area_struct
*first_vma(struct task_struct
*tsk
,
1076 struct vm_area_struct
*gate_vma
)
1078 struct vm_area_struct
*ret
= tsk
->mm
->mmap
;
1086 * Helper function for iterating across a vma list. It ensures that the caller
1087 * will visit `gate_vma' prior to terminating the search.
1089 static struct vm_area_struct
*next_vma(struct vm_area_struct
*this_vma
,
1090 struct vm_area_struct
*gate_vma
)
1092 struct vm_area_struct
*ret
;
1094 ret
= this_vma
->vm_next
;
1097 if (this_vma
== gate_vma
)
1102 static void free_vma_snapshot(struct coredump_params
*cprm
)
1104 if (cprm
->vma_meta
) {
1106 for (i
= 0; i
< cprm
->vma_count
; i
++) {
1107 struct file
*file
= cprm
->vma_meta
[i
].file
;
1111 kvfree(cprm
->vma_meta
);
1112 cprm
->vma_meta
= NULL
;
1117 * Under the mmap_lock, take a snapshot of relevant information about the task's
1120 static bool dump_vma_snapshot(struct coredump_params
*cprm
)
1122 struct vm_area_struct
*vma
, *gate_vma
;
1123 struct mm_struct
*mm
= current
->mm
;
1127 * Once the stack expansion code is fixed to not change VMA bounds
1128 * under mmap_lock in read mode, this can be changed to take the
1129 * mmap_lock in read mode.
1131 if (mmap_write_lock_killable(mm
))
1134 cprm
->vma_data_size
= 0;
1135 gate_vma
= get_gate_vma(mm
);
1136 cprm
->vma_count
= mm
->map_count
+ (gate_vma
? 1 : 0);
1138 cprm
->vma_meta
= kvmalloc_array(cprm
->vma_count
, sizeof(*cprm
->vma_meta
), GFP_KERNEL
);
1139 if (!cprm
->vma_meta
) {
1140 mmap_write_unlock(mm
);
1144 for (i
= 0, vma
= first_vma(current
, gate_vma
); vma
!= NULL
;
1145 vma
= next_vma(vma
, gate_vma
), i
++) {
1146 struct core_vma_metadata
*m
= cprm
->vma_meta
+ i
;
1148 m
->start
= vma
->vm_start
;
1149 m
->end
= vma
->vm_end
;
1150 m
->flags
= vma
->vm_flags
;
1151 m
->dump_size
= vma_dump_size(vma
, cprm
->mm_flags
);
1152 m
->pgoff
= vma
->vm_pgoff
;
1154 m
->file
= vma
->vm_file
;
1159 mmap_write_unlock(mm
);
1161 for (i
= 0; i
< cprm
->vma_count
; i
++) {
1162 struct core_vma_metadata
*m
= cprm
->vma_meta
+ i
;
1164 if (m
->dump_size
== DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER
) {
1165 char elfmag
[SELFMAG
];
1167 if (copy_from_user(elfmag
, (void __user
*)m
->start
, SELFMAG
) ||
1168 memcmp(elfmag
, ELFMAG
, SELFMAG
) != 0) {
1171 m
->dump_size
= PAGE_SIZE
;
1175 cprm
->vma_data_size
+= m
->dump_size
;