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1135 lines
28 KiB
1135 lines
28 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
#include <linux/slab.h> |
|
#include <linux/file.h> |
|
#include <linux/fdtable.h> |
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#include <linux/freezer.h> |
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#include <linux/mm.h> |
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#include <linux/stat.h> |
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#include <linux/fcntl.h> |
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#include <linux/swap.h> |
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#include <linux/ctype.h> |
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#include <linux/string.h> |
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#include <linux/init.h> |
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#include <linux/pagemap.h> |
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#include <linux/perf_event.h> |
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#include <linux/highmem.h> |
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#include <linux/spinlock.h> |
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#include <linux/key.h> |
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#include <linux/personality.h> |
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#include <linux/binfmts.h> |
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#include <linux/coredump.h> |
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#include <linux/sched/coredump.h> |
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#include <linux/sched/signal.h> |
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#include <linux/sched/task_stack.h> |
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#include <linux/utsname.h> |
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#include <linux/pid_namespace.h> |
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#include <linux/module.h> |
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#include <linux/namei.h> |
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#include <linux/mount.h> |
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#include <linux/security.h> |
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#include <linux/syscalls.h> |
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#include <linux/tsacct_kern.h> |
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#include <linux/cn_proc.h> |
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#include <linux/audit.h> |
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#include <linux/tracehook.h> |
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#include <linux/kmod.h> |
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#include <linux/fsnotify.h> |
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#include <linux/fs_struct.h> |
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#include <linux/pipe_fs_i.h> |
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#include <linux/oom.h> |
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#include <linux/compat.h> |
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#include <linux/fs.h> |
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#include <linux/path.h> |
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#include <linux/timekeeping.h> |
|
|
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#include <linux/uaccess.h> |
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#include <asm/mmu_context.h> |
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#include <asm/tlb.h> |
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#include <asm/exec.h> |
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|
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#include <trace/events/task.h> |
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#include "internal.h" |
|
|
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#include <trace/events/sched.h> |
|
|
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int core_uses_pid; |
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unsigned int core_pipe_limit; |
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char core_pattern[CORENAME_MAX_SIZE] = "core"; |
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static int core_name_size = CORENAME_MAX_SIZE; |
|
|
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struct core_name { |
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char *corename; |
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int used, size; |
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}; |
|
|
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/* The maximal length of core_pattern is also specified in sysctl.c */ |
|
|
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static int expand_corename(struct core_name *cn, int size) |
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{ |
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char *corename = krealloc(cn->corename, size, GFP_KERNEL); |
|
|
|
if (!corename) |
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return -ENOMEM; |
|
|
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if (size > core_name_size) /* racy but harmless */ |
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core_name_size = size; |
|
|
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cn->size = ksize(corename); |
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cn->corename = corename; |
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return 0; |
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} |
|
|
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static __printf(2, 0) int cn_vprintf(struct core_name *cn, const char *fmt, |
|
va_list arg) |
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{ |
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int free, need; |
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va_list arg_copy; |
|
|
|
again: |
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free = cn->size - cn->used; |
|
|
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va_copy(arg_copy, arg); |
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need = vsnprintf(cn->corename + cn->used, free, fmt, arg_copy); |
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va_end(arg_copy); |
|
|
|
if (need < free) { |
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cn->used += need; |
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return 0; |
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} |
|
|
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if (!expand_corename(cn, cn->size + need - free + 1)) |
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goto again; |
|
|
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return -ENOMEM; |
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} |
|
|
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static __printf(2, 3) int cn_printf(struct core_name *cn, const char *fmt, ...) |
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{ |
|
va_list arg; |
|
int ret; |
|
|
|
va_start(arg, fmt); |
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ret = cn_vprintf(cn, fmt, arg); |
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va_end(arg); |
|
|
|
return ret; |
|
} |
|
|
|
static __printf(2, 3) |
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int cn_esc_printf(struct core_name *cn, const char *fmt, ...) |
|
{ |
|
int cur = cn->used; |
|
va_list arg; |
|
int ret; |
|
|
|
va_start(arg, fmt); |
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ret = cn_vprintf(cn, fmt, arg); |
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va_end(arg); |
|
|
|
if (ret == 0) { |
|
/* |
|
* Ensure that this coredump name component can't cause the |
|
* resulting corefile path to consist of a ".." or ".". |
|
*/ |
|
if ((cn->used - cur == 1 && cn->corename[cur] == '.') || |
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(cn->used - cur == 2 && cn->corename[cur] == '.' |
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&& cn->corename[cur+1] == '.')) |
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cn->corename[cur] = '!'; |
|
|
|
/* |
|
* Empty names are fishy and could be used to create a "//" in a |
|
* corefile name, causing the coredump to happen one directory |
|
* level too high. Enforce that all components of the core |
|
* pattern are at least one character long. |
|
*/ |
|
if (cn->used == cur) |
|
ret = cn_printf(cn, "!"); |
|
} |
|
|
|
for (; cur < cn->used; ++cur) { |
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if (cn->corename[cur] == '/') |
|
cn->corename[cur] = '!'; |
|
} |
|
return ret; |
|
} |
|
|
|
static int cn_print_exe_file(struct core_name *cn, bool name_only) |
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{ |
|
struct file *exe_file; |
|
char *pathbuf, *path, *ptr; |
|
int ret; |
|
|
|
exe_file = get_mm_exe_file(current->mm); |
|
if (!exe_file) |
|
return cn_esc_printf(cn, "%s (path unknown)", current->comm); |
|
|
|
pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); |
|
if (!pathbuf) { |
|
ret = -ENOMEM; |
|
goto put_exe_file; |
|
} |
|
|
|
path = file_path(exe_file, pathbuf, PATH_MAX); |
|
if (IS_ERR(path)) { |
|
ret = PTR_ERR(path); |
|
goto free_buf; |
|
} |
|
|
|
if (name_only) { |
|
ptr = strrchr(path, '/'); |
|
if (ptr) |
|
path = ptr + 1; |
|
} |
|
ret = cn_esc_printf(cn, "%s", path); |
|
|
|
free_buf: |
|
kfree(pathbuf); |
|
put_exe_file: |
|
fput(exe_file); |
|
return ret; |
|
} |
|
|
|
/* format_corename will inspect the pattern parameter, and output a |
|
* name into corename, which must have space for at least |
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* CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. |
|
*/ |
|
static int format_corename(struct core_name *cn, struct coredump_params *cprm, |
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size_t **argv, int *argc) |
|
{ |
|
const struct cred *cred = current_cred(); |
|
const char *pat_ptr = core_pattern; |
|
int ispipe = (*pat_ptr == '|'); |
|
bool was_space = false; |
|
int pid_in_pattern = 0; |
|
int err = 0; |
|
|
|
cn->used = 0; |
|
cn->corename = NULL; |
|
if (expand_corename(cn, core_name_size)) |
|
return -ENOMEM; |
|
cn->corename[0] = '\0'; |
|
|
|
if (ispipe) { |
|
int argvs = sizeof(core_pattern) / 2; |
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(*argv) = kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL); |
|
if (!(*argv)) |
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return -ENOMEM; |
|
(*argv)[(*argc)++] = 0; |
|
++pat_ptr; |
|
if (!(*pat_ptr)) |
|
return -ENOMEM; |
|
} |
|
|
|
/* Repeat as long as we have more pattern to process and more output |
|
space */ |
|
while (*pat_ptr) { |
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/* |
|
* Split on spaces before doing template expansion so that |
|
* %e and %E don't get split if they have spaces in them |
|
*/ |
|
if (ispipe) { |
|
if (isspace(*pat_ptr)) { |
|
if (cn->used != 0) |
|
was_space = true; |
|
pat_ptr++; |
|
continue; |
|
} else if (was_space) { |
|
was_space = false; |
|
err = cn_printf(cn, "%c", '\0'); |
|
if (err) |
|
return err; |
|
(*argv)[(*argc)++] = cn->used; |
|
} |
|
} |
|
if (*pat_ptr != '%') { |
|
err = cn_printf(cn, "%c", *pat_ptr++); |
|
} else { |
|
switch (*++pat_ptr) { |
|
/* single % at the end, drop that */ |
|
case 0: |
|
goto out; |
|
/* Double percent, output one percent */ |
|
case '%': |
|
err = cn_printf(cn, "%c", '%'); |
|
break; |
|
/* pid */ |
|
case 'p': |
|
pid_in_pattern = 1; |
|
err = cn_printf(cn, "%d", |
|
task_tgid_vnr(current)); |
|
break; |
|
/* global pid */ |
|
case 'P': |
|
err = cn_printf(cn, "%d", |
|
task_tgid_nr(current)); |
|
break; |
|
case 'i': |
|
err = cn_printf(cn, "%d", |
|
task_pid_vnr(current)); |
|
break; |
|
case 'I': |
|
err = cn_printf(cn, "%d", |
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task_pid_nr(current)); |
|
break; |
|
/* uid */ |
|
case 'u': |
|
err = cn_printf(cn, "%u", |
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from_kuid(&init_user_ns, |
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cred->uid)); |
|
break; |
|
/* gid */ |
|
case 'g': |
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err = cn_printf(cn, "%u", |
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from_kgid(&init_user_ns, |
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cred->gid)); |
|
break; |
|
case 'd': |
|
err = cn_printf(cn, "%d", |
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__get_dumpable(cprm->mm_flags)); |
|
break; |
|
/* signal that caused the coredump */ |
|
case 's': |
|
err = cn_printf(cn, "%d", |
|
cprm->siginfo->si_signo); |
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break; |
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/* UNIX time of coredump */ |
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case 't': { |
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time64_t time; |
|
|
|
time = ktime_get_real_seconds(); |
|
err = cn_printf(cn, "%lld", time); |
|
break; |
|
} |
|
/* hostname */ |
|
case 'h': |
|
down_read(&uts_sem); |
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err = cn_esc_printf(cn, "%s", |
|
utsname()->nodename); |
|
up_read(&uts_sem); |
|
break; |
|
/* executable, could be changed by prctl PR_SET_NAME etc */ |
|
case 'e': |
|
err = cn_esc_printf(cn, "%s", current->comm); |
|
break; |
|
/* file name of executable */ |
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case 'f': |
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err = cn_print_exe_file(cn, true); |
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break; |
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case 'E': |
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err = cn_print_exe_file(cn, false); |
|
break; |
|
/* core limit size */ |
|
case 'c': |
|
err = cn_printf(cn, "%lu", |
|
rlimit(RLIMIT_CORE)); |
|
break; |
|
default: |
|
break; |
|
} |
|
++pat_ptr; |
|
} |
|
|
|
if (err) |
|
return err; |
|
} |
|
|
|
out: |
|
/* Backward compatibility with core_uses_pid: |
|
* |
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* If core_pattern does not include a %p (as is the default) |
|
* and core_uses_pid is set, then .%pid will be appended to |
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* the filename. Do not do this for piped commands. */ |
|
if (!ispipe && !pid_in_pattern && core_uses_pid) { |
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err = cn_printf(cn, ".%d", task_tgid_vnr(current)); |
|
if (err) |
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return err; |
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} |
|
return ispipe; |
|
} |
|
|
|
static int zap_process(struct task_struct *start, int exit_code, int flags) |
|
{ |
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struct task_struct *t; |
|
int nr = 0; |
|
|
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/* ignore all signals except SIGKILL, see prepare_signal() */ |
|
start->signal->flags = SIGNAL_GROUP_COREDUMP | flags; |
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start->signal->group_exit_code = exit_code; |
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start->signal->group_stop_count = 0; |
|
|
|
for_each_thread(start, t) { |
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task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); |
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if (t != current && t->mm) { |
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sigaddset(&t->pending.signal, SIGKILL); |
|
signal_wake_up(t, 1); |
|
nr++; |
|
} |
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} |
|
|
|
return nr; |
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} |
|
|
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static int zap_threads(struct task_struct *tsk, struct mm_struct *mm, |
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struct core_state *core_state, int exit_code) |
|
{ |
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struct task_struct *g, *p; |
|
unsigned long flags; |
|
int nr = -EAGAIN; |
|
|
|
spin_lock_irq(&tsk->sighand->siglock); |
|
if (!signal_group_exit(tsk->signal)) { |
|
mm->core_state = core_state; |
|
tsk->signal->group_exit_task = tsk; |
|
nr = zap_process(tsk, exit_code, 0); |
|
clear_tsk_thread_flag(tsk, TIF_SIGPENDING); |
|
} |
|
spin_unlock_irq(&tsk->sighand->siglock); |
|
if (unlikely(nr < 0)) |
|
return nr; |
|
|
|
tsk->flags |= PF_DUMPCORE; |
|
if (atomic_read(&mm->mm_users) == nr + 1) |
|
goto done; |
|
/* |
|
* We should find and kill all tasks which use this mm, and we should |
|
* count them correctly into ->nr_threads. We don't take tasklist |
|
* lock, but this is safe wrt: |
|
* |
|
* fork: |
|
* None of sub-threads can fork after zap_process(leader). All |
|
* processes which were created before this point should be |
|
* visible to zap_threads() because copy_process() adds the new |
|
* process to the tail of init_task.tasks list, and lock/unlock |
|
* of ->siglock provides a memory barrier. |
|
* |
|
* do_exit: |
|
* The caller holds mm->mmap_lock. This means that the task which |
|
* uses this mm can't pass exit_mm(), so it can't exit or clear |
|
* its ->mm. |
|
* |
|
* de_thread: |
|
* It does list_replace_rcu(&leader->tasks, ¤t->tasks), |
|
* we must see either old or new leader, this does not matter. |
|
* However, it can change p->sighand, so lock_task_sighand(p) |
|
* must be used. Since p->mm != NULL and we hold ->mmap_lock |
|
* it can't fail. |
|
* |
|
* Note also that "g" can be the old leader with ->mm == NULL |
|
* and already unhashed and thus removed from ->thread_group. |
|
* This is OK, __unhash_process()->list_del_rcu() does not |
|
* clear the ->next pointer, we will find the new leader via |
|
* next_thread(). |
|
*/ |
|
rcu_read_lock(); |
|
for_each_process(g) { |
|
if (g == tsk->group_leader) |
|
continue; |
|
if (g->flags & PF_KTHREAD) |
|
continue; |
|
|
|
for_each_thread(g, p) { |
|
if (unlikely(!p->mm)) |
|
continue; |
|
if (unlikely(p->mm == mm)) { |
|
lock_task_sighand(p, &flags); |
|
nr += zap_process(p, exit_code, |
|
SIGNAL_GROUP_EXIT); |
|
unlock_task_sighand(p, &flags); |
|
} |
|
break; |
|
} |
|
} |
|
rcu_read_unlock(); |
|
done: |
|
atomic_set(&core_state->nr_threads, nr); |
|
return nr; |
|
} |
|
|
|
static int coredump_wait(int exit_code, struct core_state *core_state) |
|
{ |
|
struct task_struct *tsk = current; |
|
struct mm_struct *mm = tsk->mm; |
|
int core_waiters = -EBUSY; |
|
|
|
init_completion(&core_state->startup); |
|
core_state->dumper.task = tsk; |
|
core_state->dumper.next = NULL; |
|
|
|
if (mmap_write_lock_killable(mm)) |
|
return -EINTR; |
|
|
|
if (!mm->core_state) |
|
core_waiters = zap_threads(tsk, mm, core_state, exit_code); |
|
mmap_write_unlock(mm); |
|
|
|
if (core_waiters > 0) { |
|
struct core_thread *ptr; |
|
|
|
freezer_do_not_count(); |
|
wait_for_completion(&core_state->startup); |
|
freezer_count(); |
|
/* |
|
* Wait for all the threads to become inactive, so that |
|
* all the thread context (extended register state, like |
|
* fpu etc) gets copied to the memory. |
|
*/ |
|
ptr = core_state->dumper.next; |
|
while (ptr != NULL) { |
|
wait_task_inactive(ptr->task, 0); |
|
ptr = ptr->next; |
|
} |
|
} |
|
|
|
return core_waiters; |
|
} |
|
|
|
static void coredump_finish(struct mm_struct *mm, bool core_dumped) |
|
{ |
|
struct core_thread *curr, *next; |
|
struct task_struct *task; |
|
|
|
spin_lock_irq(¤t->sighand->siglock); |
|
if (core_dumped && !__fatal_signal_pending(current)) |
|
current->signal->group_exit_code |= 0x80; |
|
current->signal->group_exit_task = NULL; |
|
current->signal->flags = SIGNAL_GROUP_EXIT; |
|
spin_unlock_irq(¤t->sighand->siglock); |
|
|
|
next = mm->core_state->dumper.next; |
|
while ((curr = next) != NULL) { |
|
next = curr->next; |
|
task = curr->task; |
|
/* |
|
* see exit_mm(), curr->task must not see |
|
* ->task == NULL before we read ->next. |
|
*/ |
|
smp_mb(); |
|
curr->task = NULL; |
|
wake_up_process(task); |
|
} |
|
|
|
mm->core_state = NULL; |
|
} |
|
|
|
static bool dump_interrupted(void) |
|
{ |
|
/* |
|
* SIGKILL or freezing() interrupt the coredumping. Perhaps we |
|
* can do try_to_freeze() and check __fatal_signal_pending(), |
|
* but then we need to teach dump_write() to restart and clear |
|
* TIF_SIGPENDING. |
|
*/ |
|
return fatal_signal_pending(current) || freezing(current); |
|
} |
|
|
|
static void wait_for_dump_helpers(struct file *file) |
|
{ |
|
struct pipe_inode_info *pipe = file->private_data; |
|
|
|
pipe_lock(pipe); |
|
pipe->readers++; |
|
pipe->writers--; |
|
wake_up_interruptible_sync(&pipe->rd_wait); |
|
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
|
pipe_unlock(pipe); |
|
|
|
/* |
|
* We actually want wait_event_freezable() but then we need |
|
* to clear TIF_SIGPENDING and improve dump_interrupted(). |
|
*/ |
|
wait_event_interruptible(pipe->rd_wait, pipe->readers == 1); |
|
|
|
pipe_lock(pipe); |
|
pipe->readers--; |
|
pipe->writers++; |
|
pipe_unlock(pipe); |
|
} |
|
|
|
/* |
|
* umh_pipe_setup |
|
* helper function to customize the process used |
|
* to collect the core in userspace. Specifically |
|
* it sets up a pipe and installs it as fd 0 (stdin) |
|
* for the process. Returns 0 on success, or |
|
* PTR_ERR on failure. |
|
* Note that it also sets the core limit to 1. This |
|
* is a special value that we use to trap recursive |
|
* core dumps |
|
*/ |
|
static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) |
|
{ |
|
struct file *files[2]; |
|
struct coredump_params *cp = (struct coredump_params *)info->data; |
|
int err = create_pipe_files(files, 0); |
|
if (err) |
|
return err; |
|
|
|
cp->file = files[1]; |
|
|
|
err = replace_fd(0, files[0], 0); |
|
fput(files[0]); |
|
/* and disallow core files too */ |
|
current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; |
|
|
|
return err; |
|
} |
|
|
|
void do_coredump(const kernel_siginfo_t *siginfo) |
|
{ |
|
struct core_state core_state; |
|
struct core_name cn; |
|
struct mm_struct *mm = current->mm; |
|
struct linux_binfmt * binfmt; |
|
const struct cred *old_cred; |
|
struct cred *cred; |
|
int retval = 0; |
|
int ispipe; |
|
size_t *argv = NULL; |
|
int argc = 0; |
|
/* require nonrelative corefile path and be extra careful */ |
|
bool need_suid_safe = false; |
|
bool core_dumped = false; |
|
static atomic_t core_dump_count = ATOMIC_INIT(0); |
|
struct coredump_params cprm = { |
|
.siginfo = siginfo, |
|
.regs = signal_pt_regs(), |
|
.limit = rlimit(RLIMIT_CORE), |
|
/* |
|
* We must use the same mm->flags while dumping core to avoid |
|
* inconsistency of bit flags, since this flag is not protected |
|
* by any locks. |
|
*/ |
|
.mm_flags = mm->flags, |
|
}; |
|
|
|
audit_core_dumps(siginfo->si_signo); |
|
|
|
binfmt = mm->binfmt; |
|
if (!binfmt || !binfmt->core_dump) |
|
goto fail; |
|
if (!__get_dumpable(cprm.mm_flags)) |
|
goto fail; |
|
|
|
cred = prepare_creds(); |
|
if (!cred) |
|
goto fail; |
|
/* |
|
* We cannot trust fsuid as being the "true" uid of the process |
|
* nor do we know its entire history. We only know it was tainted |
|
* so we dump it as root in mode 2, and only into a controlled |
|
* environment (pipe handler or fully qualified path). |
|
*/ |
|
if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) { |
|
/* Setuid core dump mode */ |
|
cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */ |
|
need_suid_safe = true; |
|
} |
|
|
|
retval = coredump_wait(siginfo->si_signo, &core_state); |
|
if (retval < 0) |
|
goto fail_creds; |
|
|
|
old_cred = override_creds(cred); |
|
|
|
ispipe = format_corename(&cn, &cprm, &argv, &argc); |
|
|
|
if (ispipe) { |
|
int argi; |
|
int dump_count; |
|
char **helper_argv; |
|
struct subprocess_info *sub_info; |
|
|
|
if (ispipe < 0) { |
|
printk(KERN_WARNING "format_corename failed\n"); |
|
printk(KERN_WARNING "Aborting core\n"); |
|
goto fail_unlock; |
|
} |
|
|
|
if (cprm.limit == 1) { |
|
/* See umh_pipe_setup() which sets RLIMIT_CORE = 1. |
|
* |
|
* Normally core limits are irrelevant to pipes, since |
|
* we're not writing to the file system, but we use |
|
* cprm.limit of 1 here as a special value, this is a |
|
* consistent way to catch recursive crashes. |
|
* We can still crash if the core_pattern binary sets |
|
* RLIM_CORE = !1, but it runs as root, and can do |
|
* lots of stupid things. |
|
* |
|
* Note that we use task_tgid_vnr here to grab the pid |
|
* of the process group leader. That way we get the |
|
* right pid if a thread in a multi-threaded |
|
* core_pattern process dies. |
|
*/ |
|
printk(KERN_WARNING |
|
"Process %d(%s) has RLIMIT_CORE set to 1\n", |
|
task_tgid_vnr(current), current->comm); |
|
printk(KERN_WARNING "Aborting core\n"); |
|
goto fail_unlock; |
|
} |
|
cprm.limit = RLIM_INFINITY; |
|
|
|
dump_count = atomic_inc_return(&core_dump_count); |
|
if (core_pipe_limit && (core_pipe_limit < dump_count)) { |
|
printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", |
|
task_tgid_vnr(current), current->comm); |
|
printk(KERN_WARNING "Skipping core dump\n"); |
|
goto fail_dropcount; |
|
} |
|
|
|
helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv), |
|
GFP_KERNEL); |
|
if (!helper_argv) { |
|
printk(KERN_WARNING "%s failed to allocate memory\n", |
|
__func__); |
|
goto fail_dropcount; |
|
} |
|
for (argi = 0; argi < argc; argi++) |
|
helper_argv[argi] = cn.corename + argv[argi]; |
|
helper_argv[argi] = NULL; |
|
|
|
retval = -ENOMEM; |
|
sub_info = call_usermodehelper_setup(helper_argv[0], |
|
helper_argv, NULL, GFP_KERNEL, |
|
umh_pipe_setup, NULL, &cprm); |
|
if (sub_info) |
|
retval = call_usermodehelper_exec(sub_info, |
|
UMH_WAIT_EXEC); |
|
|
|
kfree(helper_argv); |
|
if (retval) { |
|
printk(KERN_INFO "Core dump to |%s pipe failed\n", |
|
cn.corename); |
|
goto close_fail; |
|
} |
|
} else { |
|
struct user_namespace *mnt_userns; |
|
struct inode *inode; |
|
int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW | |
|
O_LARGEFILE | O_EXCL; |
|
|
|
if (cprm.limit < binfmt->min_coredump) |
|
goto fail_unlock; |
|
|
|
if (need_suid_safe && cn.corename[0] != '/') { |
|
printk(KERN_WARNING "Pid %d(%s) can only dump core "\ |
|
"to fully qualified path!\n", |
|
task_tgid_vnr(current), current->comm); |
|
printk(KERN_WARNING "Skipping core dump\n"); |
|
goto fail_unlock; |
|
} |
|
|
|
/* |
|
* Unlink the file if it exists unless this is a SUID |
|
* binary - in that case, we're running around with root |
|
* privs and don't want to unlink another user's coredump. |
|
*/ |
|
if (!need_suid_safe) { |
|
/* |
|
* If it doesn't exist, that's fine. If there's some |
|
* other problem, we'll catch it at the filp_open(). |
|
*/ |
|
do_unlinkat(AT_FDCWD, getname_kernel(cn.corename)); |
|
} |
|
|
|
/* |
|
* There is a race between unlinking and creating the |
|
* file, but if that causes an EEXIST here, that's |
|
* fine - another process raced with us while creating |
|
* the corefile, and the other process won. To userspace, |
|
* what matters is that at least one of the two processes |
|
* writes its coredump successfully, not which one. |
|
*/ |
|
if (need_suid_safe) { |
|
/* |
|
* Using user namespaces, normal user tasks can change |
|
* their current->fs->root to point to arbitrary |
|
* directories. Since the intention of the "only dump |
|
* with a fully qualified path" rule is to control where |
|
* coredumps may be placed using root privileges, |
|
* current->fs->root must not be used. Instead, use the |
|
* root directory of init_task. |
|
*/ |
|
struct path root; |
|
|
|
task_lock(&init_task); |
|
get_fs_root(init_task.fs, &root); |
|
task_unlock(&init_task); |
|
cprm.file = file_open_root(&root, cn.corename, |
|
open_flags, 0600); |
|
path_put(&root); |
|
} else { |
|
cprm.file = filp_open(cn.corename, open_flags, 0600); |
|
} |
|
if (IS_ERR(cprm.file)) |
|
goto fail_unlock; |
|
|
|
inode = file_inode(cprm.file); |
|
if (inode->i_nlink > 1) |
|
goto close_fail; |
|
if (d_unhashed(cprm.file->f_path.dentry)) |
|
goto close_fail; |
|
/* |
|
* AK: actually i see no reason to not allow this for named |
|
* pipes etc, but keep the previous behaviour for now. |
|
*/ |
|
if (!S_ISREG(inode->i_mode)) |
|
goto close_fail; |
|
/* |
|
* Don't dump core if the filesystem changed owner or mode |
|
* of the file during file creation. This is an issue when |
|
* a process dumps core while its cwd is e.g. on a vfat |
|
* filesystem. |
|
*/ |
|
mnt_userns = file_mnt_user_ns(cprm.file); |
|
if (!uid_eq(i_uid_into_mnt(mnt_userns, inode), current_fsuid())) |
|
goto close_fail; |
|
if ((inode->i_mode & 0677) != 0600) |
|
goto close_fail; |
|
if (!(cprm.file->f_mode & FMODE_CAN_WRITE)) |
|
goto close_fail; |
|
if (do_truncate(mnt_userns, cprm.file->f_path.dentry, |
|
0, 0, cprm.file)) |
|
goto close_fail; |
|
} |
|
|
|
/* get us an unshared descriptor table; almost always a no-op */ |
|
/* The cell spufs coredump code reads the file descriptor tables */ |
|
retval = unshare_files(); |
|
if (retval) |
|
goto close_fail; |
|
if (!dump_interrupted()) { |
|
/* |
|
* umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would |
|
* have this set to NULL. |
|
*/ |
|
if (!cprm.file) { |
|
pr_info("Core dump to |%s disabled\n", cn.corename); |
|
goto close_fail; |
|
} |
|
file_start_write(cprm.file); |
|
core_dumped = binfmt->core_dump(&cprm); |
|
/* |
|
* Ensures that file size is big enough to contain the current |
|
* file postion. This prevents gdb from complaining about |
|
* a truncated file if the last "write" to the file was |
|
* dump_skip. |
|
*/ |
|
if (cprm.to_skip) { |
|
cprm.to_skip--; |
|
dump_emit(&cprm, "", 1); |
|
} |
|
file_end_write(cprm.file); |
|
} |
|
if (ispipe && core_pipe_limit) |
|
wait_for_dump_helpers(cprm.file); |
|
close_fail: |
|
if (cprm.file) |
|
filp_close(cprm.file, NULL); |
|
fail_dropcount: |
|
if (ispipe) |
|
atomic_dec(&core_dump_count); |
|
fail_unlock: |
|
kfree(argv); |
|
kfree(cn.corename); |
|
coredump_finish(mm, core_dumped); |
|
revert_creds(old_cred); |
|
fail_creds: |
|
put_cred(cred); |
|
fail: |
|
return; |
|
} |
|
|
|
/* |
|
* Core dumping helper functions. These are the only things you should |
|
* do on a core-file: use only these functions to write out all the |
|
* necessary info. |
|
*/ |
|
static int __dump_emit(struct coredump_params *cprm, const void *addr, int nr) |
|
{ |
|
struct file *file = cprm->file; |
|
loff_t pos = file->f_pos; |
|
ssize_t n; |
|
if (cprm->written + nr > cprm->limit) |
|
return 0; |
|
|
|
|
|
if (dump_interrupted()) |
|
return 0; |
|
n = __kernel_write(file, addr, nr, &pos); |
|
if (n != nr) |
|
return 0; |
|
file->f_pos = pos; |
|
cprm->written += n; |
|
cprm->pos += n; |
|
|
|
return 1; |
|
} |
|
|
|
static int __dump_skip(struct coredump_params *cprm, size_t nr) |
|
{ |
|
static char zeroes[PAGE_SIZE]; |
|
struct file *file = cprm->file; |
|
if (file->f_op->llseek && file->f_op->llseek != no_llseek) { |
|
if (dump_interrupted() || |
|
file->f_op->llseek(file, nr, SEEK_CUR) < 0) |
|
return 0; |
|
cprm->pos += nr; |
|
return 1; |
|
} else { |
|
while (nr > PAGE_SIZE) { |
|
if (!__dump_emit(cprm, zeroes, PAGE_SIZE)) |
|
return 0; |
|
nr -= PAGE_SIZE; |
|
} |
|
return __dump_emit(cprm, zeroes, nr); |
|
} |
|
} |
|
|
|
int dump_emit(struct coredump_params *cprm, const void *addr, int nr) |
|
{ |
|
if (cprm->to_skip) { |
|
if (!__dump_skip(cprm, cprm->to_skip)) |
|
return 0; |
|
cprm->to_skip = 0; |
|
} |
|
return __dump_emit(cprm, addr, nr); |
|
} |
|
EXPORT_SYMBOL(dump_emit); |
|
|
|
void dump_skip_to(struct coredump_params *cprm, unsigned long pos) |
|
{ |
|
cprm->to_skip = pos - cprm->pos; |
|
} |
|
EXPORT_SYMBOL(dump_skip_to); |
|
|
|
void dump_skip(struct coredump_params *cprm, size_t nr) |
|
{ |
|
cprm->to_skip += nr; |
|
} |
|
EXPORT_SYMBOL(dump_skip); |
|
|
|
#ifdef CONFIG_ELF_CORE |
|
int dump_user_range(struct coredump_params *cprm, unsigned long start, |
|
unsigned long len) |
|
{ |
|
unsigned long addr; |
|
|
|
for (addr = start; addr < start + len; addr += PAGE_SIZE) { |
|
struct page *page; |
|
int stop; |
|
|
|
/* |
|
* To avoid having to allocate page tables for virtual address |
|
* ranges that have never been used yet, and also to make it |
|
* easy to generate sparse core files, use a helper that returns |
|
* NULL when encountering an empty page table entry that would |
|
* otherwise have been filled with the zero page. |
|
*/ |
|
page = get_dump_page(addr); |
|
if (page) { |
|
void *kaddr = kmap_local_page(page); |
|
|
|
stop = !dump_emit(cprm, kaddr, PAGE_SIZE); |
|
kunmap_local(kaddr); |
|
put_page(page); |
|
if (stop) |
|
return 0; |
|
} else { |
|
dump_skip(cprm, PAGE_SIZE); |
|
} |
|
} |
|
return 1; |
|
} |
|
#endif |
|
|
|
int dump_align(struct coredump_params *cprm, int align) |
|
{ |
|
unsigned mod = (cprm->pos + cprm->to_skip) & (align - 1); |
|
if (align & (align - 1)) |
|
return 0; |
|
if (mod) |
|
cprm->to_skip += align - mod; |
|
return 1; |
|
} |
|
EXPORT_SYMBOL(dump_align); |
|
|
|
/* |
|
* The purpose of always_dump_vma() is to make sure that special kernel mappings |
|
* that are useful for post-mortem analysis are included in every core dump. |
|
* In that way we ensure that the core dump is fully interpretable later |
|
* without matching up the same kernel and hardware config to see what PC values |
|
* meant. These special mappings include - vDSO, vsyscall, and other |
|
* architecture specific mappings |
|
*/ |
|
static bool always_dump_vma(struct vm_area_struct *vma) |
|
{ |
|
/* Any vsyscall mappings? */ |
|
if (vma == get_gate_vma(vma->vm_mm)) |
|
return true; |
|
|
|
/* |
|
* Assume that all vmas with a .name op should always be dumped. |
|
* If this changes, a new vm_ops field can easily be added. |
|
*/ |
|
if (vma->vm_ops && vma->vm_ops->name && vma->vm_ops->name(vma)) |
|
return true; |
|
|
|
/* |
|
* arch_vma_name() returns non-NULL for special architecture mappings, |
|
* such as vDSO sections. |
|
*/ |
|
if (arch_vma_name(vma)) |
|
return true; |
|
|
|
return false; |
|
} |
|
|
|
/* |
|
* Decide how much of @vma's contents should be included in a core dump. |
|
*/ |
|
static unsigned long vma_dump_size(struct vm_area_struct *vma, |
|
unsigned long mm_flags) |
|
{ |
|
#define FILTER(type) (mm_flags & (1UL << MMF_DUMP_##type)) |
|
|
|
/* always dump the vdso and vsyscall sections */ |
|
if (always_dump_vma(vma)) |
|
goto whole; |
|
|
|
if (vma->vm_flags & VM_DONTDUMP) |
|
return 0; |
|
|
|
/* support for DAX */ |
|
if (vma_is_dax(vma)) { |
|
if ((vma->vm_flags & VM_SHARED) && FILTER(DAX_SHARED)) |
|
goto whole; |
|
if (!(vma->vm_flags & VM_SHARED) && FILTER(DAX_PRIVATE)) |
|
goto whole; |
|
return 0; |
|
} |
|
|
|
/* Hugetlb memory check */ |
|
if (is_vm_hugetlb_page(vma)) { |
|
if ((vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_SHARED)) |
|
goto whole; |
|
if (!(vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_PRIVATE)) |
|
goto whole; |
|
return 0; |
|
} |
|
|
|
/* Do not dump I/O mapped devices or special mappings */ |
|
if (vma->vm_flags & VM_IO) |
|
return 0; |
|
|
|
/* By default, dump shared memory if mapped from an anonymous file. */ |
|
if (vma->vm_flags & VM_SHARED) { |
|
if (file_inode(vma->vm_file)->i_nlink == 0 ? |
|
FILTER(ANON_SHARED) : FILTER(MAPPED_SHARED)) |
|
goto whole; |
|
return 0; |
|
} |
|
|
|
/* Dump segments that have been written to. */ |
|
if ((!IS_ENABLED(CONFIG_MMU) || vma->anon_vma) && FILTER(ANON_PRIVATE)) |
|
goto whole; |
|
if (vma->vm_file == NULL) |
|
return 0; |
|
|
|
if (FILTER(MAPPED_PRIVATE)) |
|
goto whole; |
|
|
|
/* |
|
* If this is the beginning of an executable file mapping, |
|
* dump the first page to aid in determining what was mapped here. |
|
*/ |
|
if (FILTER(ELF_HEADERS) && |
|
vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ) && |
|
(READ_ONCE(file_inode(vma->vm_file)->i_mode) & 0111) != 0) |
|
return PAGE_SIZE; |
|
|
|
#undef FILTER |
|
|
|
return 0; |
|
|
|
whole: |
|
return vma->vm_end - vma->vm_start; |
|
} |
|
|
|
static struct vm_area_struct *first_vma(struct task_struct *tsk, |
|
struct vm_area_struct *gate_vma) |
|
{ |
|
struct vm_area_struct *ret = tsk->mm->mmap; |
|
|
|
if (ret) |
|
return ret; |
|
return gate_vma; |
|
} |
|
|
|
/* |
|
* Helper function for iterating across a vma list. It ensures that the caller |
|
* will visit `gate_vma' prior to terminating the search. |
|
*/ |
|
static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma, |
|
struct vm_area_struct *gate_vma) |
|
{ |
|
struct vm_area_struct *ret; |
|
|
|
ret = this_vma->vm_next; |
|
if (ret) |
|
return ret; |
|
if (this_vma == gate_vma) |
|
return NULL; |
|
return gate_vma; |
|
} |
|
|
|
/* |
|
* Under the mmap_lock, take a snapshot of relevant information about the task's |
|
* VMAs. |
|
*/ |
|
int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count, |
|
struct core_vma_metadata **vma_meta, |
|
size_t *vma_data_size_ptr) |
|
{ |
|
struct vm_area_struct *vma, *gate_vma; |
|
struct mm_struct *mm = current->mm; |
|
int i; |
|
size_t vma_data_size = 0; |
|
|
|
/* |
|
* Once the stack expansion code is fixed to not change VMA bounds |
|
* under mmap_lock in read mode, this can be changed to take the |
|
* mmap_lock in read mode. |
|
*/ |
|
if (mmap_write_lock_killable(mm)) |
|
return -EINTR; |
|
|
|
gate_vma = get_gate_vma(mm); |
|
*vma_count = mm->map_count + (gate_vma ? 1 : 0); |
|
|
|
*vma_meta = kvmalloc_array(*vma_count, sizeof(**vma_meta), GFP_KERNEL); |
|
if (!*vma_meta) { |
|
mmap_write_unlock(mm); |
|
return -ENOMEM; |
|
} |
|
|
|
for (i = 0, vma = first_vma(current, gate_vma); vma != NULL; |
|
vma = next_vma(vma, gate_vma), i++) { |
|
struct core_vma_metadata *m = (*vma_meta) + i; |
|
|
|
m->start = vma->vm_start; |
|
m->end = vma->vm_end; |
|
m->flags = vma->vm_flags; |
|
m->dump_size = vma_dump_size(vma, cprm->mm_flags); |
|
|
|
vma_data_size += m->dump_size; |
|
} |
|
|
|
mmap_write_unlock(mm); |
|
|
|
if (WARN_ON(i != *vma_count)) |
|
return -EFAULT; |
|
|
|
*vma_data_size_ptr = vma_data_size; |
|
return 0; |
|
}
|
|
|