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Systemd/src/kmsg-syslogd.c

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <sys/socket.h>
#include <sys/types.h>
#include <assert.h>
#include <time.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <sys/poll.h>
#include <sys/epoll.h>
#include <sys/un.h>
#include <fcntl.h>
#include <sys/signalfd.h>
#include "util.h"
#include "log.h"
#include "sd-daemon.h"
#include "fdset.h"
#define SERVER_FD_MAX 16
#define TIMEOUT ((int) (10*MSEC_PER_SEC))
typedef struct Stream Stream;
typedef struct Server {
FDSet *syslog_fds;
int kmsg_fd;
int epoll_fd;
int signal_fd;
} Server;
static void server_done(Server *s) {
assert(s);
if (s->epoll_fd >= 0)
close_nointr_nofail(s->epoll_fd);
if (s->kmsg_fd >= 0)
close_nointr_nofail(s->kmsg_fd);
if (s->signal_fd >= 0)
close_nointr_nofail(s->signal_fd);
if (s->syslog_fds)
fdset_free(s->syslog_fds);
}
static int server_init(Server *s, unsigned n_sockets) {
int r;
unsigned i;
struct epoll_event ev;
sigset_t mask;
assert(s);
assert(n_sockets > 0);
zero(*s);
s->kmsg_fd = s->signal_fd = -1;
if ((s->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0) {
r = -errno;
log_error("Failed to create epoll object: %s", strerror(errno));
goto fail;
}
if (!(s->syslog_fds = fdset_new())) {
r = -ENOMEM;
log_error("Failed to allocate file descriptor set: %s", strerror(errno));
goto fail;
}
for (i = 0; i < n_sockets; i++) {
int fd, one = 1;
fd = SD_LISTEN_FDS_START+i;
if ((r = sd_is_socket(fd, AF_UNSPEC, SOCK_DGRAM, -1)) < 0) {
log_error("Failed to determine file descriptor type: %s", strerror(-r));
goto fail;
}
if (!r) {
log_error("Wrong file descriptor type.");
r = -EINVAL;
goto fail;
}
if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0)
log_error("SO_PASSCRED failed: %m");
zero(ev);
ev.events = EPOLLIN;
ev.data.fd = fd;
if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
r = -errno;
log_error("Failed to add server fd to epoll object: %s", strerror(errno));
goto fail;
}
if ((r = fdset_put(s->syslog_fds, fd)) < 0) {
log_error("Failed to store file descriptor in set: %s", strerror(-r));
goto fail;
}
}
if ((s->kmsg_fd = open("/dev/kmsg", O_WRONLY|O_NOCTTY|O_CLOEXEC)) < 0) {
log_error("Failed to open /dev/kmsg for logging: %m");
return -errno;
}
assert_se(sigemptyset(&mask) == 0);
sigset_add_many(&mask, SIGINT, SIGTERM, -1);
assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
if ((s->signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
log_error("signalfd(): %m");
return -errno;
}
zero(ev);
ev.events = EPOLLIN;
ev.data.fd = s->signal_fd;
if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, s->signal_fd, &ev) < 0) {
log_error("epoll_ctl(): %m");
return -errno;
}
return 0;
fail:
server_done(s);
return r;
}
static int read_priority(const char **buf) {
int priority;
size_t n;
const char *p;
int a, b, c;
assert(buf);
assert(*buf);
p = *buf;
n = strlen(p);
if (n < 3 || p[0] != '<')
goto fail;
if (p[2] == '>') {
a = b = 0;
c = undecchar(p[1]);
p += 3;
} else if (n >= 4 && p[3] == '>') {
a = 0;
b = undecchar(p[1]);
c = undecchar(p[2]);
p += 4;
} else if (n >= 5 && p[4] == '>') {
a = undecchar(p[1]);
b = undecchar(p[2]);
c = undecchar(p[3]);
p += 5;
} else
goto fail;
if (a < 0 || b < 0 || c < 0)
goto fail;
*buf = p;
priority = 100*a + 10*b + c;
return LOG_PRI(priority);
fail:
return LOG_INFO;
}
static void skip_date(const char **buf) {
enum {
LETTER,
SPACE,
NUMBER,
SPACE_OR_NUMBER,
COLON
} sequence[] = {
LETTER, LETTER, LETTER,
SPACE,
SPACE_OR_NUMBER, NUMBER,
SPACE,
SPACE_OR_NUMBER, NUMBER,
COLON,
SPACE_OR_NUMBER, NUMBER,
COLON,
SPACE_OR_NUMBER, NUMBER,
SPACE
};
const char *p;
unsigned i;
assert(buf);
assert(*buf);
p = *buf;
for (i = 0; i < ELEMENTSOF(sequence); i++, p++) {
if (!*p)
return;
switch (sequence[i]) {
case SPACE:
if (*p != ' ')
return;
break;
case SPACE_OR_NUMBER:
if (*p == ' ')
break;
/* fall through */
case NUMBER:
if (*p < '0' || *p > '9')
return;
break;
case LETTER:
if (!(*p >= 'A' && *p <= 'Z') &&
!(*p >= 'a' && *p <= 'z'))
return;
break;
case COLON:
if (*p != ':')
return;
break;
}
}
*buf = p;
}
static int read_process(const char **buf, struct iovec *iovec) {
const char *p;
size_t l;
assert(buf);
assert(*buf);
assert(iovec);
p = *buf;
p += strspn(p, WHITESPACE);
l = strcspn(p, WHITESPACE);
if (l <= 0 ||
p[l-1] != ':')
return 0;
l--;
if (p[l-1] == ']') {
size_t k = l-1;
for (;;) {
if (p[k] == '[') {
l = k;
break;
}
if (k == 0)
break;
k--;
}
}
iovec->iov_base = (char*) p;
iovec->iov_len = l;
*buf = p + l;
return 1;
}
static void skip_pid(const char **buf) {
const char *p;
assert(buf);
assert(*buf);
p = *buf;
if (*p != '[')
return;
p++;
p += strspn(p, "0123456789");
if (*p != ']')
return;
p++;
*buf = p;
}
static int write_message(Server *s, const char *buf, struct ucred *ucred) {
ssize_t k;
char priority[4], pid[16];
struct iovec iovec[5];
unsigned i = 0;
char *process = NULL;
int r = 0;
assert(s);
assert(buf);
/* First, set priority field */
snprintf(priority, sizeof(priority), "<%i>", read_priority(&buf));
char_array_0(priority);
IOVEC_SET_STRING(iovec[i++], priority);
/* Second, skip date */
skip_date(&buf);
/* Then, add process if set */
if (read_process(&buf, &iovec[i]) > 0)
i++;
else if (ucred && get_process_name(ucred->pid, &process) >= 0)
IOVEC_SET_STRING(iovec[i++], process);
/* Skip the stored PID if we have a better one */
if (ucred) {
snprintf(pid, sizeof(pid), "[%lu]: ", (unsigned long) ucred->pid);
char_array_0(pid);
IOVEC_SET_STRING(iovec[i++], pid);
skip_pid(&buf);
if (*buf == ':')
buf++;
buf += strspn(buf, WHITESPACE);
}
/* Is the remaining message empty? */
if (*buf) {
/* And the rest is the message */
IOVEC_SET_STRING(iovec[i++], buf);
IOVEC_SET_STRING(iovec[i++], "\n");
if ((k = writev(s->kmsg_fd, iovec, i)) <= 0) {
log_error("Failed to write log message to kmsg: %s", k < 0 ? strerror(errno) : "short write");
r = k < 0 ? -errno : -EIO;
}
}
free(process);
return r;
}
static int process_event(Server *s, struct epoll_event *ev) {
assert(s);
if (ev->events != EPOLLIN) {
log_info("Got invalid event from epoll.");
return -EIO;
}
if (ev->data.fd == s->signal_fd) {
struct signalfd_siginfo sfsi;
ssize_t n;
if ((n = read(s->signal_fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
if (n >= 0)
return -EIO;
if (errno == EINTR || errno == EAGAIN)
return 0;
return -errno;
}
log_debug("Received SIG%s", strna(signal_to_string(sfsi.ssi_signo)));
return 0;
} else {
for (;;) {
char buf[LINE_MAX+1];
struct msghdr msghdr;
struct iovec iovec;
struct ucred *ucred;
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
} control;
ssize_t n;
int k;
char *e;
zero(iovec);
iovec.iov_base = buf;
iovec.iov_len = sizeof(buf)-1;
zero(control);
zero(msghdr);
msghdr.msg_iov = &iovec;
msghdr.msg_iovlen = 1;
msghdr.msg_control = &control;
msghdr.msg_controllen = sizeof(control);
if ((n = recvmsg(ev->data.fd, &msghdr, MSG_DONTWAIT)) < 0) {
if (errno == EINTR || errno == EAGAIN)
return 1;
log_error("recvmsg() failed: %m");
return -errno;
}
if (msghdr.msg_controllen >= CMSG_LEN(sizeof(struct ucred)) &&
control.cmsghdr.cmsg_level == SOL_SOCKET &&
control.cmsghdr.cmsg_type == SCM_CREDENTIALS &&
control.cmsghdr.cmsg_len == CMSG_LEN(sizeof(struct ucred)))
ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
else
ucred = NULL;
if ((e = memchr(buf, '\n', n)))
*e = 0;
else
buf[n] = 0;
if ((k = write_message(s, strstrip(buf), ucred)) < 0)
return k;
}
}
return 1;
}
int main(int argc, char *argv[]) {
Server server;
int r = EXIT_FAILURE, n;
if (getppid() != 1) {
log_error("This program should be invoked by init only.");
return EXIT_FAILURE;
}
if (argc > 1) {
log_error("This program does not take arguments.");
return EXIT_FAILURE;
}
log_set_target(LOG_TARGET_KMSG);
log_parse_environment();
log_open();
if ((n = sd_listen_fds(true)) < 0) {
log_error("Failed to read listening file descriptors from environment: %s", strerror(-r));
return EXIT_FAILURE;
}
if (n <= 0 || n > SERVER_FD_MAX) {
log_error("No or too many file descriptors passed.");
return EXIT_FAILURE;
}
if (server_init(&server, (unsigned) n) < 0)
return EXIT_FAILURE;
log_debug("systemd-kmsg-syslogd running as pid %lu", (unsigned long) getpid());
sd_notify(false,
"READY=1\n"
"STATUS=Processing messages...");
for (;;) {
struct epoll_event event;
int k;
if ((k = epoll_wait(server.epoll_fd, &event, 1, TIMEOUT)) < 0) {
if (errno == EINTR)
continue;
log_error("epoll_wait() failed: %m");
goto fail;
}
if (k <= 0)
break;
if ((k = process_event(&server, &event)) < 0)
goto fail;
if (k == 0)
break;
}
r = EXIT_SUCCESS;
log_debug("systemd-kmsg-syslogd stopped as pid %lu", (unsigned long) getpid());
fail:
sd_notify(false,
"STATUS=Shutting down...");
server_done(&server);
return r;
}
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