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Systemd/src/logger.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 "util.h"
#include "log.h"
#include "list.h"
#include "sd-daemon.h"
#include "tcpwrap.h"
#define STREAMS_MAX 256
#define SERVER_FD_MAX 16
#define TIMEOUT ((int) (10*MSEC_PER_SEC))
typedef struct Stream Stream;
typedef struct Server {
int syslog_fd;
int kmsg_fd;
int epoll_fd;
unsigned n_server_fd;
LIST_HEAD(Stream, streams);
unsigned n_streams;
} Server;
typedef enum StreamTarget {
STREAM_SYSLOG,
STREAM_KMSG
} StreamTarget;
typedef enum StreamState {
STREAM_TARGET,
STREAM_PRIORITY,
STREAM_PROCESS,
STREAM_PREFIX,
STREAM_RUNNING
} StreamState;
struct Stream {
Server *server;
StreamState state;
int fd;
StreamTarget target;
int priority;
char *process;
pid_t pid;
uid_t uid;
gid_t gid;
bool prefix;
char buffer[LINE_MAX];
size_t length;
LIST_FIELDS(Stream, stream);
};
static int stream_log(Stream *s, char *p, usec_t ts) {
char header_priority[16], header_time[64], header_pid[16];
struct iovec iovec[5];
int priority;
assert(s);
assert(p);
priority = s->priority;
if (s->prefix &&
p[0] == '<' &&
p[1] >= '0' && p[1] <= '7' &&
p[2] == '>') {
/* Detected priority prefix */
priority = LOG_MAKEPRI(LOG_FAC(priority), (p[1] - '0'));
p += 3;
}
if (*p == 0)
return 0;
/*
* The format glibc uses to talk to the syslog daemon is:
*
* <priority>time process[pid]: msg
*
* The format the kernel uses is:
*
* <priority>msg\n
*
* We extend the latter to include the process name and pid.
*/
snprintf(header_priority, sizeof(header_priority), "<%i>",
s->target == STREAM_SYSLOG ? priority : LOG_PRI(priority));
char_array_0(header_priority);
if (s->target == STREAM_SYSLOG) {
time_t t;
struct tm *tm;
t = (time_t) (ts / USEC_PER_SEC);
if (!(tm = localtime(&t)))
return -EINVAL;
if (strftime(header_time, sizeof(header_time), "%h %e %T ", tm) <= 0)
return -EINVAL;
}
snprintf(header_pid, sizeof(header_pid), "[%lu]: ", (unsigned long) s->pid);
char_array_0(header_pid);
zero(iovec);
IOVEC_SET_STRING(iovec[0], header_priority);
if (s->target == STREAM_SYSLOG) {
struct msghdr msghdr;
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
} control;
struct ucred *ucred;
zero(control);
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);
ucred->pid = s->pid;
ucred->uid = s->uid;
ucred->gid = s->gid;
IOVEC_SET_STRING(iovec[1], header_time);
IOVEC_SET_STRING(iovec[2], s->process);
IOVEC_SET_STRING(iovec[3], header_pid);
IOVEC_SET_STRING(iovec[4], p);
zero(msghdr);
msghdr.msg_iov = iovec;
msghdr.msg_iovlen = ELEMENTSOF(iovec);
msghdr.msg_control = &control;
msghdr.msg_controllen = control.cmsghdr.cmsg_len;
if (sendmsg(s->server->syslog_fd, &msghdr, MSG_NOSIGNAL) < 0)
return -errno;
} else if (s->target == STREAM_KMSG) {
IOVEC_SET_STRING(iovec[1], s->process);
IOVEC_SET_STRING(iovec[2], header_pid);
IOVEC_SET_STRING(iovec[3], p);
IOVEC_SET_STRING(iovec[4], (char*) "\n");
if (writev(s->server->kmsg_fd, iovec, ELEMENTSOF(iovec)) < 0)
return -errno;
} else
assert_not_reached("Unknown log target");
return 0;
}
static int stream_line(Stream *s, char *p, usec_t ts) {
int r;
assert(s);
assert(p);
p = strstrip(p);
switch (s->state) {
case STREAM_TARGET:
if (streq(p, "syslog"))
s->target = STREAM_SYSLOG;
else if (streq(p, "kmsg")) {
if (s->server->kmsg_fd >= 0 && s->uid == 0)
s->target = STREAM_KMSG;
else {
log_warning("/dev/kmsg logging not available.");
return -EPERM;
}
} else {
log_warning("Failed to parse log target line.");
return -EBADMSG;
}
s->state = STREAM_PRIORITY;
return 0;
case STREAM_PRIORITY:
if ((r = safe_atoi(p, &s->priority)) < 0) {
log_warning("Failed to parse log priority line: %m");
return r;
}
if (s->priority < 0) {
log_warning("Log priority negative: %m");
return -ERANGE;
}
s->state = STREAM_PROCESS;
return 0;
case STREAM_PROCESS:
if (!(s->process = strdup(p)))
return -ENOMEM;
s->state = STREAM_PREFIX;
return 0;
case STREAM_PREFIX:
if ((r = parse_boolean(p)) < 0)
return r;
s->prefix = r;
s->state = STREAM_RUNNING;
return 0;
case STREAM_RUNNING:
return stream_log(s, p, ts);
}
assert_not_reached("Unknown stream state");
}
static int stream_scan(Stream *s, usec_t ts) {
char *p;
size_t remaining;
int r = 0;
assert(s);
p = s->buffer;
remaining = s->length;
for (;;) {
char *newline;
if (!(newline = memchr(p, '\n', remaining)))
break;
*newline = 0;
if ((r = stream_line(s, p, ts)) >= 0) {
remaining -= newline-p+1;
p = newline+1;
}
}
if (p > s->buffer) {
memmove(s->buffer, p, remaining);
s->length = remaining;
}
return r;
}
static int stream_process(Stream *s, usec_t ts) {
ssize_t l;
int r;
assert(s);
if ((l = read(s->fd, s->buffer+s->length, LINE_MAX-s->length)) < 0) {
if (errno == EAGAIN)
return 0;
log_warning("Failed to read from stream: %m");
return -1;
}
if (l == 0)
return 0;
s->length += l;
r = stream_scan(s, ts);
if (r < 0)
return r;
return 1;
}
static void stream_free(Stream *s) {
assert(s);
if (s->server) {
assert(s->server->n_streams > 0);
s->server->n_streams--;
LIST_REMOVE(Stream, stream, s->server->streams, s);
}
if (s->fd >= 0) {
if (s->server)
epoll_ctl(s->server->epoll_fd, EPOLL_CTL_DEL, s->fd, NULL);
close_nointr_nofail(s->fd);
}
free(s->process);
free(s);
}
static int stream_new(Server *s, int server_fd) {
Stream *stream;
int fd;
struct ucred ucred;
socklen_t len = sizeof(ucred);
struct epoll_event ev;
int r;
assert(s);
if ((fd = accept4(server_fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC)) < 0)
return -errno;
if (s->n_streams >= STREAMS_MAX) {
log_warning("Too many connections, refusing connection.");
close_nointr_nofail(fd);
return 0;
}
if (!socket_tcpwrap(fd, "systemd-logger")) {
close_nointr_nofail(fd);
return 0;
}
if (!(stream = new0(Stream, 1))) {
close_nointr_nofail(fd);
return -ENOMEM;
}
stream->fd = fd;
if (getsockopt(stream->fd, SOL_SOCKET, SO_PEERCRED, &ucred, &len) < 0) {
r = -errno;
goto fail;
}
if (shutdown(fd, SHUT_WR) < 0) {
r = -errno;
goto fail;
}
zero(ev);
ev.data.ptr = stream;
ev.events = EPOLLIN;
if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
r = -errno;
goto fail;
}
stream->pid = ucred.pid;
stream->uid = ucred.uid;
stream->gid = ucred.gid;
stream->server = s;
LIST_PREPEND(Stream, stream, s->streams, stream);
s->n_streams ++;
return 0;
fail:
stream_free(stream);
return r;
}
static void server_done(Server *s) {
unsigned i;
assert(s);
while (s->streams)
stream_free(s->streams);
for (i = 0; i < s->n_server_fd; i++)
close_nointr_nofail(SD_LISTEN_FDS_START+i);
if (s->syslog_fd >= 0)
close_nointr_nofail(s->syslog_fd);
if (s->epoll_fd >= 0)
close_nointr_nofail(s->epoll_fd);
if (s->kmsg_fd >= 0)
close_nointr_nofail(s->kmsg_fd);
}
static int server_init(Server *s, unsigned n_sockets) {
int r;
unsigned i;
union {
struct sockaddr sa;
struct sockaddr_un un;
} sa;
assert(s);
assert(n_sockets > 0);
zero(*s);
s->n_server_fd = n_sockets;
s->syslog_fd = -1;
s->kmsg_fd = -1;
if ((s->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0) {
r = -errno;
log_error("Failed to create epoll object: %m");
goto fail;
}
for (i = 0; i < n_sockets; i++) {
struct epoll_event ev;
int fd;
fd = SD_LISTEN_FDS_START+i;
if ((r = sd_is_socket(fd, AF_UNSPEC, SOCK_STREAM, 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;
}
/* We use ev.data.ptr instead of ev.data.fd here,
* since on 64bit archs fd is 32bit while a pointer is
* 64bit. To make sure we can easily distuingish fd
* values and pointer values we want to make sure to
* write the full field unconditionally. */
zero(ev);
ev.events = EPOLLIN;
ev.data.ptr = INT_TO_PTR(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: %m");
goto fail;
}
}
if ((s->syslog_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
r = -errno;
log_error("Failed to create log fd: %m");
goto fail;
}
zero(sa);
sa.un.sun_family = AF_UNIX;
strncpy(sa.un.sun_path, "/dev/log", sizeof(sa.un.sun_path));
if (connect(s->syslog_fd, &sa.sa, sizeof(sa)) < 0) {
r = -errno;
log_error("Failed to connect log socket to /dev/log: %m");
goto fail;
}
/* /dev/kmsg logging is strictly optional */
if ((s->kmsg_fd = open("/dev/kmsg", O_WRONLY|O_NOCTTY|O_CLOEXEC)) < 0)
log_warning("Failed to open /dev/kmsg for logging, disabling kernel log buffer support: %m");
return 0;
fail:
server_done(s);
return r;
}
static int process_event(Server *s, struct epoll_event *ev) {
int r;
assert(s);
/* Yes, this is a bit ugly, we assume that that valid pointers
* are > SD_LISTEN_FDS_START+SERVER_FD_MAX. Which is certainly
* true on Linux (and probably most other OSes, too, since the
* first 4k usually are part of a seperate null pointer
* dereference page. */
if (PTR_TO_INT(ev->data.ptr) >= SD_LISTEN_FDS_START &&
PTR_TO_INT(ev->data.ptr) < SD_LISTEN_FDS_START+(int)s->n_server_fd) {
if (ev->events != EPOLLIN) {
log_info("Got invalid event from epoll. (1)");
return -EIO;
}
if ((r = stream_new(s, PTR_TO_INT(ev->data.ptr))) < 0) {
log_info("Failed to accept new connection: %s", strerror(-r));
return r;
}
} else {
usec_t ts;
Stream *stream = ev->data.ptr;
ts = now(CLOCK_REALTIME);
if (!(ev->events & EPOLLIN)) {
log_info("Got invalid event from epoll. (2)");
stream_free(stream);
return 0;
}
if ((r = stream_process(stream, ts)) <= 0) {
if (r < 0)
log_info("Got error on stream: %s", strerror(-r));
stream_free(stream);
return 0;
}
}
return 0;
}
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_SYSLOG_OR_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-logger running as pid %lu", (unsigned long) getpid());
sd_notify(false,
"READY=1\n"
"STATUS=Processing requests...");
for (;;) {
struct epoll_event event;
int k;
if ((k = epoll_wait(server.epoll_fd,
&event, 1,
server.n_streams <= 0 ? TIMEOUT : -1)) < 0) {
if (errno == EINTR)
continue;
log_error("epoll_wait() failed: %m");
goto fail;
}
if (k <= 0)
break;
if (process_event(&server, &event) < 0)
goto fail;
}
r = EXIT_SUCCESS;
log_debug("systemd-logger stopped as pid %lu", (unsigned long) getpid());
fail:
sd_notify(false,
"STATUS=Shutting down...");
server_done(&server);
return r;
}
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