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Systemd/src/journal/journald-stream.c
Lennart Poettering e22aa3d328 journald: never block when sending messages on NOTIFY_SOCKET socket 
Otherwise we might run into deadlocks, when journald blocks on the
notify socket on PID 1, and PID 1 blocks on IPC to dbus-daemon and
dbus-daemon blocks on logging to journald. Break this cycle by making
sure that journald never ever blocks on PID 1.

Note that this change disables support for event loop watchdog support,
as these messages are sent in blocking style by sd-event. That should
not be a big loss though, as people reported frequent problems with the
watchdog hitting journald on excessively slow IO.

Fixes: #1505.
2015-11-01 22:12:29 +01:00

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2011 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 <stddef.h>
#include <unistd.h>
#ifdef HAVE_SELINUX
#include <selinux/selinux.h>
#endif
#include "sd-daemon.h"
#include "sd-event.h"
#include "alloc-util.h"
#include "dirent-util.h"
#include "escape.h"
#include "fd-util.h"
#include "fileio.h"
#include "io-util.h"
#include "journald-console.h"
#include "journald-kmsg.h"
#include "journald-server.h"
#include "journald-stream.h"
#include "journald-syslog.h"
#include "journald-wall.h"
#include "mkdir.h"
#include "parse-util.h"
#include "selinux-util.h"
#include "socket-util.h"
#include "stdio-util.h"
#include "string-util.h"
#include "syslog-util.h"
#define STDOUT_STREAMS_MAX 4096
typedef enum StdoutStreamState {
STDOUT_STREAM_IDENTIFIER,
STDOUT_STREAM_UNIT_ID,
STDOUT_STREAM_PRIORITY,
STDOUT_STREAM_LEVEL_PREFIX,
STDOUT_STREAM_FORWARD_TO_SYSLOG,
STDOUT_STREAM_FORWARD_TO_KMSG,
STDOUT_STREAM_FORWARD_TO_CONSOLE,
STDOUT_STREAM_RUNNING
} StdoutStreamState;
struct StdoutStream {
Server *server;
StdoutStreamState state;
int fd;
struct ucred ucred;
char *label;
char *identifier;
char *unit_id;
int priority;
bool level_prefix:1;
bool forward_to_syslog:1;
bool forward_to_kmsg:1;
bool forward_to_console:1;
bool fdstore:1;
bool in_notify_queue:1;
char buffer[LINE_MAX+1];
size_t length;
sd_event_source *event_source;
char *state_file;
LIST_FIELDS(StdoutStream, stdout_stream);
LIST_FIELDS(StdoutStream, stdout_stream_notify_queue);
};
void stdout_stream_free(StdoutStream *s) {
if (!s)
return;
if (s->server) {
assert(s->server->n_stdout_streams > 0);
s->server->n_stdout_streams --;
LIST_REMOVE(stdout_stream, s->server->stdout_streams, s);
if (s->in_notify_queue)
LIST_REMOVE(stdout_stream_notify_queue, s->server->stdout_streams_notify_queue, s);
}
if (s->event_source) {
sd_event_source_set_enabled(s->event_source, SD_EVENT_OFF);
s->event_source = sd_event_source_unref(s->event_source);
}
safe_close(s->fd);
free(s->label);
free(s->identifier);
free(s->unit_id);
free(s->state_file);
free(s);
}
DEFINE_TRIVIAL_CLEANUP_FUNC(StdoutStream*, stdout_stream_free);
static void stdout_stream_destroy(StdoutStream *s) {
if (!s)
return;
if (s->state_file)
(void) unlink(s->state_file);
stdout_stream_free(s);
}
static int stdout_stream_save(StdoutStream *s) {
_cleanup_free_ char *temp_path = NULL;
_cleanup_fclose_ FILE *f = NULL;
int r;
assert(s);
if (s->state != STDOUT_STREAM_RUNNING)
return 0;
if (!s->state_file) {
struct stat st;
r = fstat(s->fd, &st);
if (r < 0)
return log_warning_errno(errno, "Failed to stat connected stream: %m");
/* We use device and inode numbers as identifier for the stream */
if (asprintf(&s->state_file, "/run/systemd/journal/streams/%lu:%lu", (unsigned long) st.st_dev, (unsigned long) st.st_ino) < 0)
return log_oom();
}
mkdir_p("/run/systemd/journal/streams", 0755);
r = fopen_temporary(s->state_file, &f, &temp_path);
if (r < 0)
goto fail;
fprintf(f,
"# This is private data. Do not parse\n"
"PRIORITY=%i\n"
"LEVEL_PREFIX=%i\n"
"FORWARD_TO_SYSLOG=%i\n"
"FORWARD_TO_KMSG=%i\n"
"FORWARD_TO_CONSOLE=%i\n",
s->priority,
s->level_prefix,
s->forward_to_syslog,
s->forward_to_kmsg,
s->forward_to_console);
if (!isempty(s->identifier)) {
_cleanup_free_ char *escaped;
escaped = cescape(s->identifier);
if (!escaped) {
r = -ENOMEM;
goto fail;
}
fprintf(f, "IDENTIFIER=%s\n", escaped);
}
if (!isempty(s->unit_id)) {
_cleanup_free_ char *escaped;
escaped = cescape(s->unit_id);
if (!escaped) {
r = -ENOMEM;
goto fail;
}
fprintf(f, "UNIT=%s\n", escaped);
}
r = fflush_and_check(f);
if (r < 0)
goto fail;
if (rename(temp_path, s->state_file) < 0) {
r = -errno;
goto fail;
}
if (!s->fdstore && !s->in_notify_queue) {
LIST_PREPEND(stdout_stream_notify_queue, s->server->stdout_streams_notify_queue, s);
s->in_notify_queue = true;
if (s->server->notify_event_source) {
r = sd_event_source_set_enabled(s->server->notify_event_source, SD_EVENT_ON);
if (r < 0)
log_warning_errno(r, "Failed to enable notify event source: %m");
}
}
return 0;
fail:
(void) unlink(s->state_file);
if (temp_path)
(void) unlink(temp_path);
return log_error_errno(r, "Failed to save stream data %s: %m", s->state_file);
}
static int stdout_stream_log(StdoutStream *s, const char *p) {
struct iovec iovec[N_IOVEC_META_FIELDS + 5];
int priority;
char syslog_priority[] = "PRIORITY=\0";
char syslog_facility[sizeof("SYSLOG_FACILITY=")-1 + DECIMAL_STR_MAX(int) + 1];
_cleanup_free_ char *message = NULL, *syslog_identifier = NULL;
unsigned n = 0;
size_t label_len;
assert(s);
assert(p);
if (isempty(p))
return 0;
priority = s->priority;
if (s->level_prefix)
syslog_parse_priority(&p, &priority, false);
if (s->forward_to_syslog || s->server->forward_to_syslog)
server_forward_syslog(s->server, syslog_fixup_facility(priority), s->identifier, p, &s->ucred, NULL);
if (s->forward_to_kmsg || s->server->forward_to_kmsg)
server_forward_kmsg(s->server, priority, s->identifier, p, &s->ucred);
if (s->forward_to_console || s->server->forward_to_console)
server_forward_console(s->server, priority, s->identifier, p, &s->ucred);
if (s->server->forward_to_wall)
server_forward_wall(s->server, priority, s->identifier, p, &s->ucred);
IOVEC_SET_STRING(iovec[n++], "_TRANSPORT=stdout");
syslog_priority[strlen("PRIORITY=")] = '0' + LOG_PRI(priority);
IOVEC_SET_STRING(iovec[n++], syslog_priority);
if (priority & LOG_FACMASK) {
xsprintf(syslog_facility, "SYSLOG_FACILITY=%i", LOG_FAC(priority));
IOVEC_SET_STRING(iovec[n++], syslog_facility);
}
if (s->identifier) {
syslog_identifier = strappend("SYSLOG_IDENTIFIER=", s->identifier);
if (syslog_identifier)
IOVEC_SET_STRING(iovec[n++], syslog_identifier);
}
message = strappend("MESSAGE=", p);
if (message)
IOVEC_SET_STRING(iovec[n++], message);
label_len = s->label ? strlen(s->label) : 0;
server_dispatch_message(s->server, iovec, n, ELEMENTSOF(iovec), &s->ucred, NULL, s->label, label_len, s->unit_id, priority, 0);
return 0;
}
static int stdout_stream_line(StdoutStream *s, char *p) {
int r;
assert(s);
assert(p);
p = strstrip(p);
switch (s->state) {
case STDOUT_STREAM_IDENTIFIER:
if (isempty(p))
s->identifier = NULL;
else {
s->identifier = strdup(p);
if (!s->identifier)
return log_oom();
}
s->state = STDOUT_STREAM_UNIT_ID;
return 0;
case STDOUT_STREAM_UNIT_ID:
if (s->ucred.uid == 0) {
if (isempty(p))
s->unit_id = NULL;
else {
s->unit_id = strdup(p);
if (!s->unit_id)
return log_oom();
}
}
s->state = STDOUT_STREAM_PRIORITY;
return 0;
case STDOUT_STREAM_PRIORITY:
r = safe_atoi(p, &s->priority);
if (r < 0 || s->priority < 0 || s->priority > 999) {
log_warning("Failed to parse log priority line.");
return -EINVAL;
}
s->state = STDOUT_STREAM_LEVEL_PREFIX;
return 0;
case STDOUT_STREAM_LEVEL_PREFIX:
r = parse_boolean(p);
if (r < 0) {
log_warning("Failed to parse level prefix line.");
return -EINVAL;
}
s->level_prefix = !!r;
s->state = STDOUT_STREAM_FORWARD_TO_SYSLOG;
return 0;
case STDOUT_STREAM_FORWARD_TO_SYSLOG:
r = parse_boolean(p);
if (r < 0) {
log_warning("Failed to parse forward to syslog line.");
return -EINVAL;
}
s->forward_to_syslog = !!r;
s->state = STDOUT_STREAM_FORWARD_TO_KMSG;
return 0;
case STDOUT_STREAM_FORWARD_TO_KMSG:
r = parse_boolean(p);
if (r < 0) {
log_warning("Failed to parse copy to kmsg line.");
return -EINVAL;
}
s->forward_to_kmsg = !!r;
s->state = STDOUT_STREAM_FORWARD_TO_CONSOLE;
return 0;
case STDOUT_STREAM_FORWARD_TO_CONSOLE:
r = parse_boolean(p);
if (r < 0) {
log_warning("Failed to parse copy to console line.");
return -EINVAL;
}
s->forward_to_console = !!r;
s->state = STDOUT_STREAM_RUNNING;
/* Try to save the stream, so that journald can be restarted and we can recover */
(void) stdout_stream_save(s);
return 0;
case STDOUT_STREAM_RUNNING:
return stdout_stream_log(s, p);
}
assert_not_reached("Unknown stream state");
}
static int stdout_stream_scan(StdoutStream *s, bool force_flush) {
char *p;
size_t remaining;
int r;
assert(s);
p = s->buffer;
remaining = s->length;
for (;;) {
char *end;
size_t skip;
end = memchr(p, '\n', remaining);
if (end)
skip = end - p + 1;
else if (remaining >= sizeof(s->buffer) - 1) {
end = p + sizeof(s->buffer) - 1;
skip = remaining;
} else
break;
*end = 0;
r = stdout_stream_line(s, p);
if (r < 0)
return r;
remaining -= skip;
p += skip;
}
if (force_flush && remaining > 0) {
p[remaining] = 0;
r = stdout_stream_line(s, p);
if (r < 0)
return r;
p += remaining;
remaining = 0;
}
if (p > s->buffer) {
memmove(s->buffer, p, remaining);
s->length = remaining;
}
return 0;
}
static int stdout_stream_process(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
StdoutStream *s = userdata;
ssize_t l;
int r;
assert(s);
if ((revents|EPOLLIN|EPOLLHUP) != (EPOLLIN|EPOLLHUP)) {
log_error("Got invalid event from epoll for stdout stream: %"PRIx32, revents);
goto terminate;
}
l = read(s->fd, s->buffer+s->length, sizeof(s->buffer)-1-s->length);
if (l < 0) {
if (errno == EAGAIN)
return 0;
log_warning_errno(errno, "Failed to read from stream: %m");
goto terminate;
}
if (l == 0) {
stdout_stream_scan(s, true);
goto terminate;
}
s->length += l;
r = stdout_stream_scan(s, false);
if (r < 0)
goto terminate;
return 1;
terminate:
stdout_stream_destroy(s);
return 0;
}
static int stdout_stream_install(Server *s, int fd, StdoutStream **ret) {
_cleanup_(stdout_stream_freep) StdoutStream *stream = NULL;
int r;
assert(s);
assert(fd >= 0);
stream = new0(StdoutStream, 1);
if (!stream)
return log_oom();
stream->fd = -1;
stream->priority = LOG_INFO;
r = getpeercred(fd, &stream->ucred);
if (r < 0)
return log_error_errno(r, "Failed to determine peer credentials: %m");
if (mac_selinux_use()) {
r = getpeersec(fd, &stream->label);
if (r < 0 && r != -EOPNOTSUPP)
(void) log_warning_errno(r, "Failed to determine peer security context: %m");
}
(void) shutdown(fd, SHUT_WR);
r = sd_event_add_io(s->event, &stream->event_source, fd, EPOLLIN, stdout_stream_process, stream);
if (r < 0)
return log_error_errno(r, "Failed to add stream to event loop: %m");
r = sd_event_source_set_priority(stream->event_source, SD_EVENT_PRIORITY_NORMAL+5);
if (r < 0)
return log_error_errno(r, "Failed to adjust stdout event source priority: %m");
stream->fd = fd;
stream->server = s;
LIST_PREPEND(stdout_stream, s->stdout_streams, stream);
s->n_stdout_streams ++;
if (ret)
*ret = stream;
stream = NULL;
return 0;
}
static int stdout_stream_new(sd_event_source *es, int listen_fd, uint32_t revents, void *userdata) {
_cleanup_close_ int fd = -1;
Server *s = userdata;
int r;
assert(s);
if (revents != EPOLLIN) {
log_error("Got invalid event from epoll for stdout server fd: %"PRIx32, revents);
return -EIO;
}
fd = accept4(s->stdout_fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
if (fd < 0) {
if (errno == EAGAIN)
return 0;
log_error_errno(errno, "Failed to accept stdout connection: %m");
return -errno;
}
if (s->n_stdout_streams >= STDOUT_STREAMS_MAX) {
log_warning("Too many stdout streams, refusing connection.");
return 0;
}
r = stdout_stream_install(s, fd, NULL);
if (r < 0)
return r;
fd = -1;
return 0;
}
static int stdout_stream_load(StdoutStream *stream, const char *fname) {
_cleanup_free_ char
*priority = NULL,
*level_prefix = NULL,
*forward_to_syslog = NULL,
*forward_to_kmsg = NULL,
*forward_to_console = NULL;
int r;
assert(stream);
assert(fname);
if (!stream->state_file) {
stream->state_file = strappend("/run/systemd/journal/streams/", fname);
if (!stream->state_file)
return log_oom();
}
r = parse_env_file(stream->state_file, NEWLINE,
"PRIORITY", &priority,
"LEVEL_PREFIX", &level_prefix,
"FORWARD_TO_SYSLOG", &forward_to_syslog,
"FORWARD_TO_KMSG", &forward_to_kmsg,
"FORWARD_TO_CONSOLE", &forward_to_console,
"IDENTIFIER", &stream->identifier,
"UNIT", &stream->unit_id,
NULL);
if (r < 0)
return log_error_errno(r, "Failed to read: %s", stream->state_file);
if (priority) {
int p;
p = log_level_from_string(priority);
if (p >= 0)
stream->priority = p;
}
if (level_prefix) {
r = parse_boolean(level_prefix);
if (r >= 0)
stream->level_prefix = r;
}
if (forward_to_syslog) {
r = parse_boolean(forward_to_syslog);
if (r >= 0)
stream->forward_to_syslog = r;
}
if (forward_to_kmsg) {
r = parse_boolean(forward_to_kmsg);
if (r >= 0)
stream->forward_to_kmsg = r;
}
if (forward_to_console) {
r = parse_boolean(forward_to_console);
if (r >= 0)
stream->forward_to_console = r;
}
return 0;
}
static int stdout_stream_restore(Server *s, const char *fname, int fd) {
StdoutStream *stream;
int r;
assert(s);
assert(fname);
assert(fd >= 0);
if (s->n_stdout_streams >= STDOUT_STREAMS_MAX) {
log_warning("Too many stdout streams, refusing restoring of stream.");
return -ENOBUFS;
}
r = stdout_stream_install(s, fd, &stream);
if (r < 0)
return r;
stream->state = STDOUT_STREAM_RUNNING;
stream->fdstore = true;
/* Ignore all parsing errors */
(void) stdout_stream_load(stream, fname);
return 0;
}
int server_restore_streams(Server *s, FDSet *fds) {
_cleanup_closedir_ DIR *d = NULL;
struct dirent *de;
int r;
d = opendir("/run/systemd/journal/streams");
if (!d) {
if (errno == ENOENT)
return 0;
return log_warning_errno(errno, "Failed to enumerate /run/systemd/journal/streams: %m");
}
FOREACH_DIRENT(de, d, goto fail) {
unsigned long st_dev, st_ino;
bool found = false;
Iterator i;
int fd;
if (sscanf(de->d_name, "%lu:%lu", &st_dev, &st_ino) != 2)
continue;
FDSET_FOREACH(fd, fds, i) {
struct stat st;
if (fstat(fd, &st) < 0)
return log_error_errno(errno, "Failed to stat %s: %m", de->d_name);
if (S_ISSOCK(st.st_mode) && st.st_dev == st_dev && st.st_ino == st_ino) {
found = true;
break;
}
}
if (!found) {
/* No file descriptor? Then let's delete the state file */
log_debug("Cannot restore stream file %s", de->d_name);
unlinkat(dirfd(d), de->d_name, 0);
continue;
}
fdset_remove(fds, fd);
r = stdout_stream_restore(s, de->d_name, fd);
if (r < 0)
safe_close(fd);
}
return 0;
fail:
return log_error_errno(errno, "Failed to read streams directory: %m");
}
int server_open_stdout_socket(Server *s) {
int r;
assert(s);
if (s->stdout_fd < 0) {
union sockaddr_union sa = {
.un.sun_family = AF_UNIX,
.un.sun_path = "/run/systemd/journal/stdout",
};
s->stdout_fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (s->stdout_fd < 0)
return log_error_errno(errno, "socket() failed: %m");
unlink(sa.un.sun_path);
r = bind(s->stdout_fd, &sa.sa, offsetof(union sockaddr_union, un.sun_path) + strlen(sa.un.sun_path));
if (r < 0)
return log_error_errno(errno, "bind(%s) failed: %m", sa.un.sun_path);
(void) chmod(sa.un.sun_path, 0666);
if (listen(s->stdout_fd, SOMAXCONN) < 0)
return log_error_errno(errno, "listen(%s) failed: %m", sa.un.sun_path);
} else
fd_nonblock(s->stdout_fd, 1);
r = sd_event_add_io(s->event, &s->stdout_event_source, s->stdout_fd, EPOLLIN, stdout_stream_new, s);
if (r < 0)
return log_error_errno(r, "Failed to add stdout server fd to event source: %m");
r = sd_event_source_set_priority(s->stdout_event_source, SD_EVENT_PRIORITY_NORMAL+10);
if (r < 0)
return log_error_errno(r, "Failed to adjust priority of stdout server event source: %m");
return 0;
}
void stdout_stream_send_notify(StdoutStream *s) {
struct iovec iovec = {
.iov_base = (char*) "FDSTORE=1",
.iov_len = strlen("FDSTORE=1"),
};
struct msghdr msghdr = {
.msg_iov = &iovec,
.msg_iovlen = 1,
};
struct cmsghdr *cmsg;
ssize_t l;
assert(s);
assert(!s->fdstore);
assert(s->in_notify_queue);
assert(s->server);
assert(s->server->notify_fd >= 0);
/* Store the connection fd in PID 1, so that we get it passed
* in again on next start */
msghdr.msg_controllen = CMSG_SPACE(sizeof(int));
msghdr.msg_control = alloca0(msghdr.msg_controllen);
cmsg = CMSG_FIRSTHDR(&msghdr);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
memcpy(CMSG_DATA(cmsg), &s->fd, sizeof(int));
l = sendmsg(s->server->notify_fd, &msghdr, MSG_DONTWAIT|MSG_NOSIGNAL);
if (l < 0) {
if (errno == EAGAIN)
return;
log_error_errno(errno, "Failed to send stream file descriptor to service manager: %m");
} else {
log_debug("Successfully sent stream file descriptor to service manager.");
s->fdstore = 1;
}
LIST_REMOVE(stdout_stream_notify_queue, s->server->stdout_streams_notify_queue, s);
s->in_notify_queue = false;
}
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