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Systemd/src/journal/coredump.c

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2012 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/prctl.h>
#include <sys/types.h>
#include <sys/xattr.h>
#ifdef HAVE_ELFUTILS
# include <dwarf.h>
# include <elfutils/libdwfl.h>
#endif
#include "systemd/sd-journal.h"
#include "systemd/sd-login.h"
#include "log.h"
#include "util.h"
#include "strv.h"
#include "macro.h"
#include "mkdir.h"
#include "special.h"
#include "cgroup-util.h"
#include "journald-native.h"
#include "conf-parser.h"
#include "copy.h"
#include "stacktrace.h"
#include "path-util.h"
#include "compress.h"
#include "coredump-vacuum.h"
#ifdef HAVE_ACL
# include <sys/acl.h>
# include "acl-util.h"
#endif
/* The maximum size up to which we process coredumps */
#define PROCESS_SIZE_MAX ((off_t) (2LLU*1024LLU*1024LLU*1024LLU))
/* The maximum size up to which we leave the coredump around on
* disk */
#define EXTERNAL_SIZE_MAX PROCESS_SIZE_MAX
/* The maximum size up to which we store the coredump in the
* journal */
#define JOURNAL_SIZE_MAX ((size_t) (767LU*1024LU*1024LU))
/* Make sure to not make this larger than the maximum journal entry
* size. See DATA_SIZE_MAX in journald-native.c. */
assert_cc(JOURNAL_SIZE_MAX <= DATA_SIZE_MAX);
enum {
INFO_PID,
INFO_UID,
INFO_GID,
INFO_SIGNAL,
INFO_TIMESTAMP,
INFO_COMM,
INFO_EXE,
_INFO_LEN
};
typedef enum CoredumpStorage {
COREDUMP_STORAGE_NONE,
COREDUMP_STORAGE_EXTERNAL,
COREDUMP_STORAGE_JOURNAL,
COREDUMP_STORAGE_BOTH,
_COREDUMP_STORAGE_MAX,
_COREDUMP_STORAGE_INVALID = -1
} CoredumpStorage;
static const char* const coredump_storage_table[_COREDUMP_STORAGE_MAX] = {
[COREDUMP_STORAGE_NONE] = "none",
[COREDUMP_STORAGE_EXTERNAL] = "external",
[COREDUMP_STORAGE_JOURNAL] = "journal",
[COREDUMP_STORAGE_BOTH] = "both",
};
DEFINE_PRIVATE_STRING_TABLE_LOOKUP(coredump_storage, CoredumpStorage);
static DEFINE_CONFIG_PARSE_ENUM(config_parse_coredump_storage, coredump_storage, CoredumpStorage, "Failed to parse storage setting");
static CoredumpStorage arg_storage = COREDUMP_STORAGE_EXTERNAL;
static bool arg_compress = true;
static off_t arg_process_size_max = PROCESS_SIZE_MAX;
static off_t arg_external_size_max = EXTERNAL_SIZE_MAX;
static size_t arg_journal_size_max = JOURNAL_SIZE_MAX;
static off_t arg_keep_free = (off_t) -1;
static off_t arg_max_use = (off_t) -1;
static int parse_config(void) {
static const ConfigTableItem items[] = {
{ "Coredump", "Storage", config_parse_coredump_storage, 0, &arg_storage },
{ "Coredump", "Compress", config_parse_bool, 0, &arg_compress },
{ "Coredump", "ProcessSizeMax", config_parse_iec_off, 0, &arg_process_size_max },
{ "Coredump", "ExternalSizeMax", config_parse_iec_off, 0, &arg_external_size_max },
{ "Coredump", "JournalSizeMax", config_parse_iec_size, 0, &arg_journal_size_max },
{ "Coredump", "KeepFree", config_parse_iec_off, 0, &arg_keep_free },
{ "Coredump", "MaxUse", config_parse_iec_off, 0, &arg_max_use },
{}
};
return config_parse(NULL, "/etc/systemd/coredump.conf", NULL,
"Coredump\0",
config_item_table_lookup, items,
false, false, true, NULL);
}
static int fix_acl(int fd, uid_t uid) {
#ifdef HAVE_ACL
_cleanup_(acl_freep) acl_t acl = NULL;
acl_entry_t entry;
acl_permset_t permset;
assert(fd >= 0);
if (uid <= SYSTEM_UID_MAX)
return 0;
/* Make sure normal users can read (but not write or delete)
* their own coredumps */
acl = acl_get_fd(fd);
if (!acl) {
log_error("Failed to get ACL: %m");
return -errno;
}
if (acl_create_entry(&acl, &entry) < 0 ||
acl_set_tag_type(entry, ACL_USER) < 0 ||
acl_set_qualifier(entry, &uid) < 0) {
log_error("Failed to patch ACL: %m");
return -errno;
}
if (acl_get_permset(entry, &permset) < 0 ||
acl_add_perm(permset, ACL_READ) < 0 ||
calc_acl_mask_if_needed(&acl) < 0) {
log_warning("Failed to patch ACL: %m");
return -errno;
}
if (acl_set_fd(fd, acl) < 0) {
log_error("Failed to apply ACL: %m");
return -errno;
}
#endif
return 0;
}
static int fix_xattr(int fd, const char *info[_INFO_LEN]) {
static const char * const xattrs[_INFO_LEN] = {
[INFO_PID] = "user.coredump.pid",
[INFO_UID] = "user.coredump.uid",
[INFO_GID] = "user.coredump.gid",
[INFO_SIGNAL] = "user.coredump.signal",
[INFO_TIMESTAMP] = "user.coredump.timestamp",
[INFO_COMM] = "user.coredump.comm",
[INFO_EXE] = "user.coredump.exe",
};
int r = 0;
unsigned i;
assert(fd >= 0);
/* Attach some metadata to coredumps via extended
* attributes. Just because we can. */
for (i = 0; i < _INFO_LEN; i++) {
int k;
if (isempty(info[i]) || !xattrs[i])
continue;
k = fsetxattr(fd, xattrs[i], info[i], strlen(info[i]), XATTR_CREATE);
if (k < 0 && r == 0)
r = -errno;
}
return r;
}
#define filename_escape(s) xescape((s), "./ ")
static int fix_permissions(
int fd,
const char *filename,
const char *target,
const char *info[_INFO_LEN],
uid_t uid) {
assert(fd >= 0);
assert(filename);
assert(target);
assert(info);
/* Ignore errors on these */
fchmod(fd, 0640);
fix_acl(fd, uid);
fix_xattr(fd, info);
if (fsync(fd) < 0) {
log_error("Failed to sync coredump %s: %m", filename);
return -errno;
}
if (rename(filename, target) < 0) {
log_error("Failed to rename coredump %s -> %s: %m", filename, target);
return -errno;
}
return 0;
}
static int maybe_remove_external_coredump(const char *filename, off_t size) {
/* Returns 1 if might remove, 0 if will not remove, < 0 on error. */
if (IN_SET(arg_storage, COREDUMP_STORAGE_EXTERNAL, COREDUMP_STORAGE_BOTH) &&
size <= arg_external_size_max)
return 0;
if (!filename)
return 1;
if (unlink(filename) < 0 && errno != ENOENT) {
log_error("Failed to unlink %s: %m", filename);
return -errno;
}
return 1;
}
static int make_filename(const char *info[_INFO_LEN], char **ret) {
_cleanup_free_ char *c = NULL, *u = NULL, *p = NULL, *t = NULL;
sd_id128_t boot;
int r;
assert(info);
c = filename_escape(info[INFO_COMM]);
if (!c)
return -ENOMEM;
u = filename_escape(info[INFO_UID]);
if (!u)
return -ENOMEM;
r = sd_id128_get_boot(&boot);
if (r < 0)
return r;
p = filename_escape(info[INFO_PID]);
if (!p)
return -ENOMEM;
t = filename_escape(info[INFO_TIMESTAMP]);
if (!t)
return -ENOMEM;
if (asprintf(ret,
"/var/lib/systemd/coredump/core.%s.%s." SD_ID128_FORMAT_STR ".%s.%s000000",
c,
u,
SD_ID128_FORMAT_VAL(boot),
p,
t) < 0)
return -ENOMEM;
return 0;
}
static int save_external_coredump(
const char *info[_INFO_LEN],
uid_t uid,
char **ret_filename,
int *ret_fd,
off_t *ret_size) {
_cleanup_free_ char *fn = NULL, *tmp = NULL;
_cleanup_close_ int fd = -1;
struct stat st;
int r;
assert(info);
assert(ret_filename);
assert(ret_fd);
assert(ret_size);
r = make_filename(info, &fn);
if (r < 0) {
log_error("Failed to determine coredump file name: %s", strerror(-r));
return r;
}
tmp = tempfn_random(fn);
if (!tmp)
return log_oom();
mkdir_p_label("/var/lib/systemd/coredump", 0755);
fd = open(tmp, O_CREAT|O_EXCL|O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0640);
if (fd < 0) {
log_error("Failed to create coredump file %s: %m", tmp);
return -errno;
}
r = copy_bytes(STDIN_FILENO, fd, arg_process_size_max);
if (r == -EFBIG) {
log_error("Coredump of %s (%s) is larger than configured processing limit, refusing.", info[INFO_PID], info[INFO_COMM]);
goto fail;
} else if (IN_SET(r, -EDQUOT, -ENOSPC)) {
log_error("Not enough disk space for coredump of %s (%s), refusing.", info[INFO_PID], info[INFO_COMM]);
goto fail;
} else if (r < 0) {
log_error("Failed to dump coredump to file: %s", strerror(-r));
goto fail;
}
if (fstat(fd, &st) < 0) {
log_error("Failed to fstat coredump %s: %m", tmp);
goto fail;
}
if (lseek(fd, 0, SEEK_SET) == (off_t) -1) {
log_error("Failed to seek on %s: %m", tmp);
goto fail;
}
#if defined(HAVE_XZ) || defined(HAVE_LZ4)
/* If we will remove the coredump anyway, do not compress. */
if (maybe_remove_external_coredump(NULL, st.st_size) == 0
&& arg_compress) {
_cleanup_free_ char *fn_compressed = NULL, *tmp_compressed = NULL;
_cleanup_close_ int fd_compressed = -1;
fn_compressed = strappend(fn, COMPRESSED_EXT);
if (!fn_compressed) {
log_oom();
goto uncompressed;
}
tmp_compressed = tempfn_random(fn_compressed);
if (!tmp_compressed) {
log_oom();
goto uncompressed;
}
fd_compressed = open(tmp_compressed, O_CREAT|O_EXCL|O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0640);
if (fd_compressed < 0) {
log_error("Failed to create file %s: %m", tmp_compressed);
goto uncompressed;
}
r = compress_stream(fd, fd_compressed, -1);
if (r < 0) {
log_error("Failed to compress %s: %s", tmp_compressed, strerror(-r));
goto fail_compressed;
}
r = fix_permissions(fd_compressed, tmp_compressed, fn_compressed, info, uid);
if (r < 0)
goto fail_compressed;
/* OK, this worked, we can get rid of the uncompressed version now */
unlink_noerrno(tmp);
*ret_filename = fn_compressed; /* compressed */
*ret_fd = fd; /* uncompressed */
*ret_size = st.st_size; /* uncompressed */
fn_compressed = NULL;
fd = -1;
return 0;
fail_compressed:
unlink_noerrno(tmp_compressed);
}
uncompressed:
#endif
r = fix_permissions(fd, tmp, fn, info, uid);
if (r < 0)
goto fail;
*ret_filename = fn;
*ret_fd = fd;
*ret_size = st.st_size;
fn = NULL;
fd = -1;
return 0;
fail:
unlink_noerrno(tmp);
return r;
}
static int allocate_journal_field(int fd, size_t size, char **ret, size_t *ret_size) {
_cleanup_free_ char *field = NULL;
ssize_t n;
assert(fd >= 0);
assert(ret);
assert(ret_size);
if (lseek(fd, 0, SEEK_SET) == (off_t) -1) {
log_warning("Failed to seek: %m");
return -errno;
}
field = malloc(9 + size);
if (!field) {
log_warning("Failed to allocate memory for coredump, coredump will not be stored.");
return -ENOMEM;
}
memcpy(field, "COREDUMP=", 9);
n = read(fd, field + 9, size);
if (n < 0) {
log_error("Failed to read core data: %s", strerror(-n));
return (int) n;
}
if ((size_t) n < size) {
log_error("Core data too short.");
return -EIO;
}
*ret = field;
*ret_size = size + 9;
field = NULL;
return 0;
}
int main(int argc, char* argv[]) {
_cleanup_free_ char *core_pid = NULL, *core_uid = NULL, *core_gid = NULL, *core_signal = NULL,
*core_timestamp = NULL, *core_comm = NULL, *core_exe = NULL, *core_unit = NULL,
*core_session = NULL, *core_message = NULL, *core_cmdline = NULL, *coredump_data = NULL,
*core_slice = NULL, *core_cgroup = NULL, *core_owner_uid = NULL,
*exe = NULL, *comm = NULL, *filename = NULL;
const char *info[_INFO_LEN];
_cleanup_close_ int coredump_fd = -1;
struct iovec iovec[18];
off_t coredump_size;
int r, j = 0;
uid_t uid, owner_uid;
gid_t gid;
pid_t pid;
char *t;
/* Make sure we never enter a loop */
prctl(PR_SET_DUMPABLE, 0);
/* First, log to a safe place, since we don't know what
* crashed and it might be journald which we'd rather not log
* to then. */
log_set_target(LOG_TARGET_KMSG);
log_open();
if (argc < INFO_COMM + 1) {
log_error("Not enough arguments passed from kernel (%d, expected %d).",
argc - 1, INFO_COMM + 1 - 1);
r = -EINVAL;
goto finish;
}
/* Ignore all parse errors */
parse_config();
log_debug("Selected storage '%s'.", coredump_storage_to_string(arg_storage));
log_debug("Selected compression %s.", yes_no(arg_compress));
r = parse_uid(argv[INFO_UID + 1], &uid);
if (r < 0) {
log_error("Failed to parse UID.");
goto finish;
}
r = parse_pid(argv[INFO_PID + 1], &pid);
if (r < 0) {
log_error("Failed to parse PID.");
goto finish;
}
r = parse_gid(argv[INFO_GID + 1], &gid);
if (r < 0) {
log_error("Failed to parse GID.");
goto finish;
}
if (get_process_comm(pid, &comm) < 0) {
log_warning("Failed to get COMM, falling back to the command line.");
comm = strv_join(argv + INFO_COMM + 1, " ");
}
if (get_process_exe(pid, &exe) < 0)
log_warning("Failed to get EXE.");
info[INFO_PID] = argv[INFO_PID + 1];
info[INFO_UID] = argv[INFO_UID + 1];
info[INFO_GID] = argv[INFO_GID + 1];
info[INFO_SIGNAL] = argv[INFO_SIGNAL + 1];
info[INFO_TIMESTAMP] = argv[INFO_TIMESTAMP + 1];
info[INFO_COMM] = comm;
info[INFO_EXE] = exe;
if (cg_pid_get_unit(pid, &t) >= 0) {
if (streq(t, SPECIAL_JOURNALD_SERVICE)) {
/* If we are journald, we cut things short,
* don't write to the journal, but still
* create a coredump. */
if (arg_storage != COREDUMP_STORAGE_NONE)
arg_storage = COREDUMP_STORAGE_EXTERNAL;
r = save_external_coredump(info, uid, &filename, &coredump_fd, &coredump_size);
if (r < 0)
goto finish;
r = maybe_remove_external_coredump(filename, coredump_size);
if (r < 0)
goto finish;
log_info("Detected coredump of the journal daemon itself, diverted to %s.", filename);
goto finish;
}
core_unit = strappend("COREDUMP_UNIT=", t);
} else if (cg_pid_get_user_unit(pid, &t) >= 0)
core_unit = strappend("COREDUMP_USER_UNIT=", t);
if (core_unit)
IOVEC_SET_STRING(iovec[j++], core_unit);
/* OK, now we know it's not the journal, hence we can make use
* of it now. */
log_set_target(LOG_TARGET_JOURNAL_OR_KMSG);
log_open();
core_pid = strappend("COREDUMP_PID=", info[INFO_PID]);
if (core_pid)
IOVEC_SET_STRING(iovec[j++], core_pid);
core_uid = strappend("COREDUMP_UID=", info[INFO_UID]);
if (core_uid)
IOVEC_SET_STRING(iovec[j++], core_uid);
core_gid = strappend("COREDUMP_GID=", info[INFO_GID]);
if (core_gid)
IOVEC_SET_STRING(iovec[j++], core_gid);
core_signal = strappend("COREDUMP_SIGNAL=", info[INFO_SIGNAL]);
if (core_signal)
IOVEC_SET_STRING(iovec[j++], core_signal);
if (sd_pid_get_session(pid, &t) >= 0) {
core_session = strappend("COREDUMP_SESSION=", t);
free(t);
if (core_session)
IOVEC_SET_STRING(iovec[j++], core_session);
}
if (sd_pid_get_owner_uid(pid, &owner_uid) >= 0) {
r = asprintf(&core_owner_uid,
"COREDUMP_OWNER_UID=" UID_FMT, owner_uid);
if (r > 0)
IOVEC_SET_STRING(iovec[j++], core_owner_uid);
}
if (sd_pid_get_slice(pid, &t) >= 0) {
core_slice = strappend("COREDUMP_SLICE=", t);
free(t);
if (core_slice)
IOVEC_SET_STRING(iovec[j++], core_slice);
}
if (comm) {
core_comm = strappend("COREDUMP_COMM=", comm);
if (core_comm)
IOVEC_SET_STRING(iovec[j++], core_comm);
}
if (exe) {
core_exe = strappend("COREDUMP_EXE=", exe);
if (core_exe)
IOVEC_SET_STRING(iovec[j++], core_exe);
}
if (get_process_cmdline(pid, 0, false, &t) >= 0) {
core_cmdline = strappend("COREDUMP_CMDLINE=", t);
free(t);
if (core_cmdline)
IOVEC_SET_STRING(iovec[j++], core_cmdline);
}
if (cg_pid_get_path_shifted(pid, NULL, &t) >= 0) {
core_cgroup = strappend("COREDUMP_CGROUP=", t);
free(t);
if (core_cgroup)
IOVEC_SET_STRING(iovec[j++], core_cgroup);
}
core_timestamp = strjoin("COREDUMP_TIMESTAMP=", info[INFO_TIMESTAMP], "000000", NULL);
if (core_timestamp)
IOVEC_SET_STRING(iovec[j++], core_timestamp);
IOVEC_SET_STRING(iovec[j++], "MESSAGE_ID=fc2e22bc6ee647b6b90729ab34a250b1");
IOVEC_SET_STRING(iovec[j++], "PRIORITY=2");
/* Vacuum before we write anything again */
coredump_vacuum(-1, arg_keep_free, arg_max_use);
/* Always stream the coredump to disk, if that's possible */
r = save_external_coredump(info, uid, &filename, &coredump_fd, &coredump_size);
if (r < 0)
/* skip whole core dumping part */
goto log;
/* If we don't want to keep the coredump on disk, remove it
* now, as later on we will lack the privileges for
* it. However, we keep the fd to it, so that we can still
* process it and log it. */
r = maybe_remove_external_coredump(filename, coredump_size);
if (r < 0)
goto finish;
if (r == 0) {
const char *coredump_filename;
coredump_filename = strappenda("COREDUMP_FILENAME=", filename);
IOVEC_SET_STRING(iovec[j++], coredump_filename);
}
/* Vacuum again, but exclude the coredump we just created */
coredump_vacuum(coredump_fd, arg_keep_free, arg_max_use);
/* Now, let's drop privileges to become the user who owns the
* segfaulted process and allocate the coredump memory under
* the user's uid. This also ensures that the credentials
* journald will see are the ones of the coredumping user,
* thus making sure the user gets access to the core dump. */
if (setresgid(gid, gid, gid) < 0 ||
setresuid(uid, uid, uid) < 0) {
log_error("Failed to drop privileges: %m");
r = -errno;
goto finish;
}
#ifdef HAVE_ELFUTILS
/* Try to get a strack trace if we can */
if (coredump_size <= arg_process_size_max) {
_cleanup_free_ char *stacktrace = NULL;
r = coredump_make_stack_trace(coredump_fd, exe, &stacktrace);
if (r >= 0)
core_message = strjoin("MESSAGE=Process ", info[INFO_PID], " (", comm, ") of user ", info[INFO_UID], " dumped core.\n\n", stacktrace, NULL);
else if (r == -EINVAL)
log_warning("Failed to generate stack trace: %s", dwfl_errmsg(dwfl_errno()));
else
log_warning("Failed to generate stack trace: %s", strerror(-r));
}
if (!core_message)
#endif
log:
core_message = strjoin("MESSAGE=Process ", info[INFO_PID], " (", comm, ") of user ", info[INFO_UID], " dumped core.", NULL);
if (core_message)
IOVEC_SET_STRING(iovec[j++], core_message);
/* Optionally store the entire coredump in the journal */
if (IN_SET(arg_storage, COREDUMP_STORAGE_JOURNAL, COREDUMP_STORAGE_BOTH) &&
coredump_size <= (off_t) arg_journal_size_max) {
size_t sz;
/* Store the coredump itself in the journal */
r = allocate_journal_field(coredump_fd, (size_t) coredump_size, &coredump_data, &sz);
if (r >= 0) {
iovec[j].iov_base = coredump_data;
iovec[j].iov_len = sz;
j++;
}
}
r = sd_journal_sendv(iovec, j);
if (r < 0)
log_error("Failed to log coredump: %s", strerror(-r));
finish:
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}
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