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Systemd/src/journal/journald-syslog.c
Lennart Poettering d3070fbdf6 core: implement /run/systemd/units/-based path for passing unit info from PID 1 to journald 
And let's make use of it to implement two new unit settings with it:

1. LogLevelMax= is a new per-unit setting that may be used to configure
   log priority filtering: set it to LogLevelMax=notice and only
   messages of level "notice" and lower (i.e. more important) will be
   processed, all others are dropped.

2. LogExtraFields= is a new per-unit setting for configuring per-unit
   journal fields, that are implicitly included in every log record
   generated by the unit's processes. It takes field/value pairs in the
   form of FOO=BAR.

Also, related to this, one exisiting unit setting is ported to this new
facility:

3. The invocation ID is now pulled from /run/systemd/units/ instead of
   cgroupfs xattrs. This substantially relaxes requirements of systemd
   on the kernel version and the privileges it runs with (specifically,
   cgroupfs xattrs are not available in containers, since they are
   stored in kernel memory, and hence are unsafe to permit to lesser
   privileged code).

/run/systemd/units/ is a new directory, which contains a number of files
and symlinks encoding the above information. PID 1 creates and manages
these files, and journald reads them from there.

Note that this is supposed to be a direct path between PID 1 and the
journal only, due to the special runtime environment the journal runs
in. Normally, today we shouldn't introduce new interfaces that (mis-)use
a file system as IPC framework, and instead just an IPC system, but this
is very hard to do between the journal and PID 1, as long as the IPC
system is a subject PID 1 manages, and itself a client to the journal.

This patch cleans up a couple of types used in journal code:
specifically we switch to size_t for a couple of memory-sizing values,
as size_t is the right choice for everything that is memory.

Fixes: #4089
Fixes: #3041
Fixes: #4441
2017-11-16 12:40:17 +01:00

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/***
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 <sys/epoll.h>
#include <unistd.h>
#include "sd-messages.h"
#include "alloc-util.h"
#include "fd-util.h"
#include "format-util.h"
#include "io-util.h"
#include "journald-console.h"
#include "journald-kmsg.h"
#include "journald-server.h"
#include "journald-syslog.h"
#include "journald-wall.h"
#include "process-util.h"
#include "selinux-util.h"
#include "socket-util.h"
#include "stdio-util.h"
#include "string-util.h"
#include "syslog-util.h"
/* Warn once every 30s if we missed syslog message */
#define WARN_FORWARD_SYSLOG_MISSED_USEC (30 * USEC_PER_SEC)
static void forward_syslog_iovec(Server *s, const struct iovec *iovec, unsigned n_iovec, const struct ucred *ucred, const struct timeval *tv) {
static const union sockaddr_union sa = {
.un.sun_family = AF_UNIX,
.un.sun_path = "/run/systemd/journal/syslog",
};
struct msghdr msghdr = {
.msg_iov = (struct iovec *) iovec,
.msg_iovlen = n_iovec,
.msg_name = (struct sockaddr*) &sa.sa,
.msg_namelen = SOCKADDR_UN_LEN(sa.un),
};
struct cmsghdr *cmsg;
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
} control;
assert(s);
assert(iovec);
assert(n_iovec > 0);
if (ucred) {
zero(control);
msghdr.msg_control = &control;
msghdr.msg_controllen = sizeof(control);
cmsg = CMSG_FIRSTHDR(&msghdr);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_CREDENTIALS;
cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
memcpy(CMSG_DATA(cmsg), ucred, sizeof(struct ucred));
msghdr.msg_controllen = cmsg->cmsg_len;
}
/* Forward the syslog message we received via /dev/log to
* /run/systemd/syslog. Unfortunately we currently can't set
* the SO_TIMESTAMP auxiliary data, and hence we don't. */
if (sendmsg(s->syslog_fd, &msghdr, MSG_NOSIGNAL) >= 0)
return;
/* The socket is full? I guess the syslog implementation is
* too slow, and we shouldn't wait for that... */
if (errno == EAGAIN) {
s->n_forward_syslog_missed++;
return;
}
if (ucred && IN_SET(errno, ESRCH, EPERM)) {
struct ucred u;
/* Hmm, presumably the sender process vanished
* by now, or we don't have CAP_SYS_AMDIN, so
* let's fix it as good as we can, and retry */
u = *ucred;
u.pid = getpid_cached();
memcpy(CMSG_DATA(cmsg), &u, sizeof(struct ucred));
if (sendmsg(s->syslog_fd, &msghdr, MSG_NOSIGNAL) >= 0)
return;
if (errno == EAGAIN) {
s->n_forward_syslog_missed++;
return;
}
}
if (errno != ENOENT)
log_debug_errno(errno, "Failed to forward syslog message: %m");
}
static void forward_syslog_raw(Server *s, int priority, const char *buffer, const struct ucred *ucred, const struct timeval *tv) {
struct iovec iovec;
assert(s);
assert(buffer);
if (LOG_PRI(priority) > s->max_level_syslog)
return;
iovec = IOVEC_MAKE_STRING(buffer);
forward_syslog_iovec(s, &iovec, 1, ucred, tv);
}
void server_forward_syslog(Server *s, int priority, const char *identifier, const char *message, const struct ucred *ucred, const struct timeval *tv) {
struct iovec iovec[5];
char header_priority[DECIMAL_STR_MAX(priority) + 3], header_time[64],
header_pid[sizeof("[]: ")-1 + DECIMAL_STR_MAX(pid_t) + 1];
int n = 0;
time_t t;
struct tm *tm;
_cleanup_free_ char *ident_buf = NULL;
assert(s);
assert(priority >= 0);
assert(priority <= 999);
assert(message);
if (LOG_PRI(priority) > s->max_level_syslog)
return;
/* First: priority field */
xsprintf(header_priority, "<%i>", priority);
iovec[n++] = IOVEC_MAKE_STRING(header_priority);
/* Second: timestamp */
t = tv ? tv->tv_sec : ((time_t) (now(CLOCK_REALTIME) / USEC_PER_SEC));
tm = localtime(&t);
if (!tm)
return;
if (strftime(header_time, sizeof(header_time), "%h %e %T ", tm) <= 0)
return;
iovec[n++] = IOVEC_MAKE_STRING(header_time);
/* Third: identifier and PID */
if (ucred) {
if (!identifier) {
get_process_comm(ucred->pid, &ident_buf);
identifier = ident_buf;
}
xsprintf(header_pid, "["PID_FMT"]: ", ucred->pid);
if (identifier)
iovec[n++] = IOVEC_MAKE_STRING(identifier);
iovec[n++] = IOVEC_MAKE_STRING(header_pid);
} else if (identifier) {
iovec[n++] = IOVEC_MAKE_STRING(identifier);
iovec[n++] = IOVEC_MAKE_STRING(": ");
}
/* Fourth: message */
iovec[n++] = IOVEC_MAKE_STRING(message);
forward_syslog_iovec(s, iovec, n, ucred, tv);
}
int syslog_fixup_facility(int priority) {
if ((priority & LOG_FACMASK) == 0)
return (priority & LOG_PRIMASK) | LOG_USER;
return priority;
}
size_t syslog_parse_identifier(const char **buf, char **identifier, char **pid) {
const char *p;
char *t;
size_t l, e;
assert(buf);
assert(identifier);
assert(pid);
p = *buf;
p += strspn(p, WHITESPACE);
l = strcspn(p, WHITESPACE);
if (l <= 0 ||
p[l-1] != ':')
return 0;
e = l;
l--;
if (p[l-1] == ']') {
size_t k = l-1;
for (;;) {
if (p[k] == '[') {
t = strndup(p+k+1, l-k-2);
if (t)
*pid = t;
l = k;
break;
}
if (k == 0)
break;
k--;
}
}
t = strndup(p, l);
if (t)
*identifier = t;
if (strchr(WHITESPACE, p[e]))
e++;
*buf = p + e;
return e;
}
static void syslog_skip_date(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
};
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;
}
void server_process_syslog_message(
Server *s,
const char *buf,
const struct ucred *ucred,
const struct timeval *tv,
const char *label,
size_t label_len) {
char syslog_priority[sizeof("PRIORITY=") + DECIMAL_STR_MAX(int)],
syslog_facility[sizeof("SYSLOG_FACILITY=") + DECIMAL_STR_MAX(int)];
const char *message = NULL, *syslog_identifier = NULL, *syslog_pid = NULL;
_cleanup_free_ char *identifier = NULL, *pid = NULL;
int priority = LOG_USER | LOG_INFO, r;
ClientContext *context = NULL;
struct iovec *iovec;
const char *orig;
size_t n = 0, m;
assert(s);
assert(buf);
if (ucred && pid_is_valid(ucred->pid)) {
r = client_context_get(s, ucred->pid, ucred, label, label_len, NULL, &context);
if (r < 0)
log_warning_errno(r, "Failed to retrieve credentials for PID " PID_FMT ", ignoring: %m", ucred->pid);
}
orig = buf;
syslog_parse_priority(&buf, &priority, true);
if (!client_context_test_priority(context, priority))
return;
if (s->forward_to_syslog)
forward_syslog_raw(s, priority, orig, ucred, tv);
syslog_skip_date((char**) &buf);
syslog_parse_identifier(&buf, &identifier, &pid);
if (s->forward_to_kmsg)
server_forward_kmsg(s, priority, identifier, buf, ucred);
if (s->forward_to_console)
server_forward_console(s, priority, identifier, buf, ucred);
if (s->forward_to_wall)
server_forward_wall(s, priority, identifier, buf, ucred);
m = N_IOVEC_META_FIELDS + 6 + client_context_extra_fields_n_iovec(context);
iovec = newa(struct iovec, m);
iovec[n++] = IOVEC_MAKE_STRING("_TRANSPORT=syslog");
xsprintf(syslog_priority, "PRIORITY=%i", priority & LOG_PRIMASK);
iovec[n++] = IOVEC_MAKE_STRING(syslog_priority);
if (priority & LOG_FACMASK) {
xsprintf(syslog_facility, "SYSLOG_FACILITY=%i", LOG_FAC(priority));
iovec[n++] = IOVEC_MAKE_STRING(syslog_facility);
}
if (identifier) {
syslog_identifier = strjoina("SYSLOG_IDENTIFIER=", identifier);
iovec[n++] = IOVEC_MAKE_STRING(syslog_identifier);
}
if (pid) {
syslog_pid = strjoina("SYSLOG_PID=", pid);
iovec[n++] = IOVEC_MAKE_STRING(syslog_pid);
}
message = strjoina("MESSAGE=", buf);
if (message)
iovec[n++] = IOVEC_MAKE_STRING(message);
server_dispatch_message(s, iovec, n, m, context, tv, priority, 0);
}
int server_open_syslog_socket(Server *s) {
static const union sockaddr_union sa = {
.un.sun_family = AF_UNIX,
.un.sun_path = "/run/systemd/journal/dev-log",
};
static const int one = 1;
int r;
assert(s);
if (s->syslog_fd < 0) {
s->syslog_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (s->syslog_fd < 0)
return log_error_errno(errno, "socket() failed: %m");
(void) unlink(sa.un.sun_path);
r = bind(s->syslog_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un));
if (r < 0)
return log_error_errno(errno, "bind(%s) failed: %m", sa.un.sun_path);
(void) chmod(sa.un.sun_path, 0666);
} else
fd_nonblock(s->syslog_fd, 1);
r = setsockopt(s->syslog_fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one));
if (r < 0)
return log_error_errno(errno, "SO_PASSCRED failed: %m");
#if HAVE_SELINUX
if (mac_selinux_use()) {
r = setsockopt(s->syslog_fd, SOL_SOCKET, SO_PASSSEC, &one, sizeof(one));
if (r < 0)
log_warning_errno(errno, "SO_PASSSEC failed: %m");
}
#endif
r = setsockopt(s->syslog_fd, SOL_SOCKET, SO_TIMESTAMP, &one, sizeof(one));
if (r < 0)
return log_error_errno(errno, "SO_TIMESTAMP failed: %m");
r = sd_event_add_io(s->event, &s->syslog_event_source, s->syslog_fd, EPOLLIN, server_process_datagram, s);
if (r < 0)
return log_error_errno(r, "Failed to add syslog server fd to event loop: %m");
r = sd_event_source_set_priority(s->syslog_event_source, SD_EVENT_PRIORITY_NORMAL+5);
if (r < 0)
return log_error_errno(r, "Failed to adjust syslog event source priority: %m");
return 0;
}
void server_maybe_warn_forward_syslog_missed(Server *s) {
usec_t n;
assert(s);
if (s->n_forward_syslog_missed <= 0)
return;
n = now(CLOCK_MONOTONIC);
if (s->last_warn_forward_syslog_missed + WARN_FORWARD_SYSLOG_MISSED_USEC > n)
return;
server_driver_message(s, 0,
"MESSAGE_ID=" SD_MESSAGE_FORWARD_SYSLOG_MISSED_STR,
LOG_MESSAGE("Forwarding to syslog missed %u messages.",
s->n_forward_syslog_missed),
NULL);
s->n_forward_syslog_missed = 0;
s->last_warn_forward_syslog_missed = n;
}
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