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Systemd/src/journal/journald-kmsg.c

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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 <fcntl.h>
#include <sys/epoll.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <unistd.h>
#include "libudev.h"
#include "sd-messages.h"
#include "alloc-util.h"
#include "escape.h"
#include "fd-util.h"
#include "format-util.h"
#include "io-util.h"
#include "journald-kmsg.h"
#include "journald-server.h"
#include "journald-syslog.h"
#include "parse-util.h"
#include "process-util.h"
#include "stdio-util.h"
#include "string-util.h"
void server_forward_kmsg(
Server *s,
int priority,
const char *identifier,
const char *message,
const struct ucred *ucred) {
_cleanup_free_ char *ident_buf = NULL;
struct iovec iovec[5];
char header_priority[DECIMAL_STR_MAX(priority) + 3],
header_pid[sizeof("[]: ")-1 + DECIMAL_STR_MAX(pid_t) + 1];
int n = 0;
assert(s);
assert(priority >= 0);
assert(priority <= 999);
assert(message);
if (_unlikely_(LOG_PRI(priority) > s->max_level_kmsg))
return;
if (_unlikely_(s->dev_kmsg_fd < 0))
return;
/* Never allow messages with kernel facility to be written to
* kmsg, regardless where the data comes from. */
priority = syslog_fixup_facility(priority);
/* First: priority field */
xsprintf(header_priority, "<%i>", priority);
iovec[n++] = IOVEC_MAKE_STRING(header_priority);
/* Second: 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);
iovec[n++] = IOVEC_MAKE_STRING("\n");
if (writev(s->dev_kmsg_fd, iovec, n) < 0)
log_debug_errno(errno, "Failed to write to /dev/kmsg for logging: %m");
}
static bool is_us(const char *pid) {
pid_t t;
assert(pid);
if (parse_pid(pid, &t) < 0)
return false;
return t == getpid_cached();
}
static void dev_kmsg_record(Server *s, const char *p, size_t l) {
struct iovec iovec[N_IOVEC_META_FIELDS + 7 + N_IOVEC_KERNEL_FIELDS + 2 + N_IOVEC_UDEV_FIELDS];
_cleanup_free_ char *message = NULL, *syslog_priority = NULL, *syslog_pid = NULL, *syslog_facility = NULL, *syslog_identifier = NULL, *source_time = NULL, *identifier = NULL, *pid = NULL;
int priority, r;
unsigned n = 0, z = 0, j;
unsigned long long usec;
char *e, *f, *k;
uint64_t serial;
size_t pl;
char *kernel_device = NULL;
assert(s);
assert(p);
if (l <= 0)
return;
e = memchr(p, ',', l);
if (!e)
return;
*e = 0;
r = safe_atoi(p, &priority);
if (r < 0 || priority < 0 || priority > 999)
return;
if (s->forward_to_kmsg && (priority & LOG_FACMASK) != LOG_KERN)
return;
l -= (e - p) + 1;
p = e + 1;
e = memchr(p, ',', l);
if (!e)
return;
*e = 0;
r = safe_atou64(p, &serial);
if (r < 0)
return;
if (s->kernel_seqnum) {
/* We already read this one? */
if (serial < *s->kernel_seqnum)
return;
/* Did we lose any? */
if (serial > *s->kernel_seqnum)
server_driver_message(s,
"MESSAGE_ID=" SD_MESSAGE_JOURNAL_MISSED_STR,
LOG_MESSAGE("Missed %"PRIu64" kernel messages",
serial - *s->kernel_seqnum),
NULL);
/* Make sure we never read this one again. Note that
* we always store the next message serial we expect
* here, simply because this makes handling the first
* message with serial 0 easy. */
*s->kernel_seqnum = serial + 1;
}
l -= (e - p) + 1;
p = e + 1;
f = memchr(p, ';', l);
if (!f)
return;
/* Kernel 3.6 has the flags field, kernel 3.5 lacks that */
e = memchr(p, ',', l);
if (!e || f < e)
e = f;
*e = 0;
r = safe_atollu(p, &usec);
if (r < 0)
return;
l -= (f - p) + 1;
p = f + 1;
e = memchr(p, '\n', l);
if (!e)
return;
*e = 0;
pl = e - p;
l -= (e - p) + 1;
k = e + 1;
for (j = 0; l > 0 && j < N_IOVEC_KERNEL_FIELDS; j++) {
char *m;
/* Metadata fields attached */
if (*k != ' ')
break;
k++, l--;
e = memchr(k, '\n', l);
if (!e)
return;
*e = 0;
if (cunescape_length_with_prefix(k, e - k, "_KERNEL_", UNESCAPE_RELAX, &m) < 0)
break;
if (startswith(m, "_KERNEL_DEVICE="))
kernel_device = m + 15;
iovec[n++] = IOVEC_MAKE_STRING(m);
z++;
l -= (e - k) + 1;
k = e + 1;
}
if (kernel_device) {
struct udev_device *ud;
ud = udev_device_new_from_device_id(s->udev, kernel_device);
if (ud) {
const char *g;
struct udev_list_entry *ll;
char *b;
g = udev_device_get_devnode(ud);
if (g) {
b = strappend("_UDEV_DEVNODE=", g);
if (b) {
iovec[n++] = IOVEC_MAKE_STRING(b);
z++;
}
}
g = udev_device_get_sysname(ud);
if (g) {
b = strappend("_UDEV_SYSNAME=", g);
if (b) {
iovec[n++] = IOVEC_MAKE_STRING(b);
z++;
}
}
j = 0;
ll = udev_device_get_devlinks_list_entry(ud);
udev_list_entry_foreach(ll, ll) {
if (j > N_IOVEC_UDEV_FIELDS)
break;
g = udev_list_entry_get_name(ll);
if (g) {
b = strappend("_UDEV_DEVLINK=", g);
if (b) {
iovec[n++] = IOVEC_MAKE_STRING(b);
z++;
}
}
j++;
}
udev_device_unref(ud);
}
}
if (asprintf(&source_time, "_SOURCE_MONOTONIC_TIMESTAMP=%llu", usec) >= 0)
iovec[n++] = IOVEC_MAKE_STRING(source_time);
iovec[n++] = IOVEC_MAKE_STRING("_TRANSPORT=kernel");
if (asprintf(&syslog_priority, "PRIORITY=%i", priority & LOG_PRIMASK) >= 0)
iovec[n++] = IOVEC_MAKE_STRING(syslog_priority);
if (asprintf(&syslog_facility, "SYSLOG_FACILITY=%i", LOG_FAC(priority)) >= 0)
iovec[n++] = IOVEC_MAKE_STRING(syslog_facility);
if ((priority & LOG_FACMASK) == LOG_KERN)
iovec[n++] = IOVEC_MAKE_STRING("SYSLOG_IDENTIFIER=kernel");
else {
pl -= syslog_parse_identifier((const char**) &p, &identifier, &pid);
/* Avoid any messages we generated ourselves via
* log_info() and friends. */
if (pid && is_us(pid))
goto finish;
if (identifier) {
syslog_identifier = strappend("SYSLOG_IDENTIFIER=", identifier);
if (syslog_identifier)
iovec[n++] = IOVEC_MAKE_STRING(syslog_identifier);
}
if (pid) {
syslog_pid = strappend("SYSLOG_PID=", pid);
if (syslog_pid)
iovec[n++] = IOVEC_MAKE_STRING(syslog_pid);
}
}
if (cunescape_length_with_prefix(p, pl, "MESSAGE=", UNESCAPE_RELAX, &message) >= 0)
iovec[n++] = IOVEC_MAKE_STRING(message);
server_dispatch_message(s, iovec, n, ELEMENTSOF(iovec), NULL, NULL, priority, 0);
finish:
for (j = 0; j < z; j++)
free(iovec[j].iov_base);
}
static int server_read_dev_kmsg(Server *s) {
char buffer[8192+1]; /* the kernel-side limit per record is 8K currently */
ssize_t l;
assert(s);
assert(s->dev_kmsg_fd >= 0);
l = read(s->dev_kmsg_fd, buffer, sizeof(buffer) - 1);
if (l == 0)
return 0;
if (l < 0) {
/* Old kernels who don't allow reading from /dev/kmsg
* return EINVAL when we try. So handle this cleanly,
* but don' try to ever read from it again. */
if (errno == EINVAL) {
s->dev_kmsg_event_source = sd_event_source_unref(s->dev_kmsg_event_source);
return 0;
}
if (IN_SET(errno, EAGAIN, EINTR, EPIPE))
return 0;
return log_error_errno(errno, "Failed to read from kernel: %m");
}
dev_kmsg_record(s, buffer, l);
return 1;
}
int server_flush_dev_kmsg(Server *s) {
int r;
assert(s);
if (s->dev_kmsg_fd < 0)
return 0;
if (!s->dev_kmsg_readable)
return 0;
log_debug("Flushing /dev/kmsg...");
for (;;) {
r = server_read_dev_kmsg(s);
if (r < 0)
return r;
if (r == 0)
break;
}
return 0;
}
static int dispatch_dev_kmsg(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
Server *s = userdata;
assert(es);
assert(fd == s->dev_kmsg_fd);
assert(s);
if (revents & EPOLLERR)
log_warning("/dev/kmsg buffer overrun, some messages lost.");
if (!(revents & EPOLLIN))
log_error("Got invalid event from epoll for /dev/kmsg: %"PRIx32, revents);
return server_read_dev_kmsg(s);
}
int server_open_dev_kmsg(Server *s) {
mode_t mode;
int r;
assert(s);
if (s->read_kmsg)
mode = O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY;
else
mode = O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY;
s->dev_kmsg_fd = open("/dev/kmsg", mode);
if (s->dev_kmsg_fd < 0) {
log_full(errno == ENOENT ? LOG_DEBUG : LOG_WARNING,
"Failed to open /dev/kmsg, ignoring: %m");
return 0;
}
if (!s->read_kmsg)
return 0;
r = sd_event_add_io(s->event, &s->dev_kmsg_event_source, s->dev_kmsg_fd, EPOLLIN, dispatch_dev_kmsg, s);
if (r < 0) {
/* This will fail with EPERM on older kernels where
* /dev/kmsg is not readable. */
if (r == -EPERM) {
r = 0;
goto fail;
}
log_error_errno(r, "Failed to add /dev/kmsg fd to event loop: %m");
goto fail;
}
r = sd_event_source_set_priority(s->dev_kmsg_event_source, SD_EVENT_PRIORITY_IMPORTANT+10);
if (r < 0) {
log_error_errno(r, "Failed to adjust priority of kmsg event source: %m");
goto fail;
}
s->dev_kmsg_readable = true;
return 0;
fail:
s->dev_kmsg_event_source = sd_event_source_unref(s->dev_kmsg_event_source);
s->dev_kmsg_fd = safe_close(s->dev_kmsg_fd);
return r;
}
int server_open_kernel_seqnum(Server *s) {
_cleanup_close_ int fd;
uint64_t *p;
int r;
assert(s);
/* We store the seqnum we last read in an mmaped file. That
* way we can just use it like a variable, but it is
* persistent and automatically flushed at reboot. */
fd = open("/run/systemd/journal/kernel-seqnum", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0644);
if (fd < 0) {
log_error_errno(errno, "Failed to open /run/systemd/journal/kernel-seqnum, ignoring: %m");
return 0;
}
r = posix_fallocate(fd, 0, sizeof(uint64_t));
if (r != 0) {
log_error_errno(r, "Failed to allocate sequential number file, ignoring: %m");
return 0;
}
p = mmap(NULL, sizeof(uint64_t), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (p == MAP_FAILED) {
log_error_errno(errno, "Failed to map sequential number file, ignoring: %m");
return 0;
}
s->kernel_seqnum = p;
return 0;
}
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