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Systemd/src/journal/coredump.c

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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 <systemd/sd-journal.h>
#ifdef HAVE_LOGIND
#include <systemd/sd-login.h>
#endif
#include "log.h"
#include "util.h"
#include "mkdir.h"
#include "special.h"
#include "cgroup-util.h"
#define COREDUMP_MAX (24*1024*1024)
enum {
ARG_PID = 1,
ARG_UID,
ARG_GID,
ARG_SIGNAL,
ARG_TIMESTAMP,
ARG_COMM,
_ARG_MAX
};
static int divert_coredump(void) {
FILE *f;
int r;
log_info("Detected coredump of the journal daemon itself, diverting coredump to /var/lib/systemd/coredump/.");
mkdir_p_label("/var/lib/systemd/coredump", 0755);
f = fopen("/var/lib/systemd/coredump/core.systemd-journald", "we");
if (!f) {
log_error("Failed to create coredump file: %m");
return -errno;
}
for (;;) {
uint8_t buffer[4096];
size_t l, q;
l = fread(buffer, 1, sizeof(buffer), stdin);
if (l <= 0) {
if (ferror(f)) {
log_error("Failed to read coredump: %m");
r = -errno;
goto finish;
}
r = 0;
break;
}
q = fwrite(buffer, 1, l, f);
if (q != l) {
log_error("Failed to write coredump: %m");
r = -errno;
goto finish;
}
}
fflush(f);
if (ferror(f)) {
log_error("Failed to write coredump: %m");
r = -errno;
}
finish:
fclose(f);
return r;
}
int main(int argc, char* argv[]) {
int r, j = 0;
char *p = NULL;
ssize_t n;
pid_t pid;
uid_t uid;
gid_t gid;
struct iovec iovec[14];
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, *t;
prctl(PR_SET_DUMPABLE, 0);
if (argc != _ARG_MAX) {
log_set_target(LOG_TARGET_JOURNAL_OR_KMSG);
log_open();
log_error("Invalid number of arguments passed from kernel.");
r = -EINVAL;
goto finish;
}
r = parse_pid(argv[ARG_PID], &pid);
if (r < 0) {
log_set_target(LOG_TARGET_JOURNAL_OR_KMSG);
log_open();
log_error("Failed to parse PID.");
goto finish;
}
if (cg_pid_get_unit(pid, &t) >= 0) {
if (streq(t, SPECIAL_JOURNALD_SERVICE)) {
/* Make sure we don't make use of the journal,
* if it's the journal which is crashing */
log_set_target(LOG_TARGET_KMSG);
log_open();
r = divert_coredump();
goto finish;
}
core_unit = strappend("COREDUMP_UNIT=", t);
free(t);
if (core_unit)
IOVEC_SET_STRING(iovec[j++], core_unit);
}
/* OK, now we know it's not the journal, hence make use of
* it */
log_set_target(LOG_TARGET_JOURNAL_OR_KMSG);
log_open();
r = parse_uid(argv[ARG_UID], &uid);
if (r < 0) {
log_error("Failed to parse UID.");
goto finish;
}
r = parse_gid(argv[ARG_GID], &gid);
if (r < 0) {
log_error("Failed to parse GID.");
goto finish;
}
core_pid = strappend("COREDUMP_PID=", argv[ARG_PID]);
if (core_pid)
IOVEC_SET_STRING(iovec[j++], core_pid);
core_uid = strappend("COREDUMP_UID=", argv[ARG_UID]);
if (core_uid)
IOVEC_SET_STRING(iovec[j++], core_uid);
core_gid = strappend("COREDUMP_GID=", argv[ARG_GID]);
if (core_gid)
IOVEC_SET_STRING(iovec[j++], core_gid);
core_signal = strappend("COREDUMP_SIGNAL=", argv[ARG_SIGNAL]);
if (core_signal)
IOVEC_SET_STRING(iovec[j++], core_signal);
core_comm = strappend("COREDUMP_COMM=", argv[ARG_COMM]);
if (core_comm)
IOVEC_SET_STRING(iovec[j++], core_comm);
#ifdef HAVE_LOGIND
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);
}
#endif
if (get_process_exe(pid, &t) >= 0) {
core_exe = strappend("COREDUMP_EXE=", t);
free(t);
if (core_exe)
IOVEC_SET_STRING(iovec[j++], core_exe);
}
if (get_process_cmdline(pid, LINE_MAX, false, &t) >= 0) {
core_cmdline = strappend("COREDUMP_CMDLINE=", t);
free(t);
if (core_cmdline)
IOVEC_SET_STRING(iovec[j++], core_cmdline);
}
core_timestamp = strjoin("COREDUMP_TIMESTAMP=", argv[ARG_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");
core_message = strjoin("MESSAGE=Process ", argv[ARG_PID], " (", argv[ARG_COMM], ") dumped core.", NULL);
if (core_message)
IOVEC_SET_STRING(iovec[j++], core_message);
/* Now, let's drop privileges to become the user who owns the
* segfaulted process and allocate the coredump memory under
* his uid. This also ensures that the credentials journald
* will see are the ones of the coredumping user, thus making
* sure the user himself 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;
}
p = malloc(9 + COREDUMP_MAX);
if (!p) {
r = log_oom();
goto finish;
}
memcpy(p, "COREDUMP=", 9);
n = loop_read(STDIN_FILENO, p + 9, COREDUMP_MAX, false);
if (n < 0) {
log_error("Failed to read core dump data: %s", strerror(-n));
r = (int) n;
goto finish;
}
iovec[j].iov_base = p;
iovec[j].iov_len = 9 + n;
j++;
r = sd_journal_sendv(iovec, j);
if (r < 0)
log_error("Failed to send coredump: %s", strerror(-r));
finish:
free(p);
free(core_pid);
free(core_uid);
free(core_gid);
free(core_signal);
free(core_timestamp);
free(core_comm);
free(core_exe);
free(core_cmdline);
free(core_unit);
free(core_session);
free(core_message);
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}
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