]> git.ipfire.org Git - thirdparty/systemd.git/blob - src/journal/journald-kmsg.c
Always prefer our headers to system headers
[thirdparty/systemd.git] / src / journal / journald-kmsg.c
1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
2
3 /***
4 This file is part of systemd.
5
6 Copyright 2011 Lennart Poettering
7
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
12
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
17
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
20 ***/
21
22 #include <unistd.h>
23 #include <sys/epoll.h>
24 #include <fcntl.h>
25 #include <sys/mman.h>
26 #include <sys/socket.h>
27
28 #include "systemd/sd-messages.h"
29 #include <libudev.h>
30
31 #include "journald-server.h"
32 #include "journald-kmsg.h"
33 #include "journald-syslog.h"
34
35 void server_forward_kmsg(
36 Server *s,
37 int priority,
38 const char *identifier,
39 const char *message,
40 struct ucred *ucred) {
41
42 struct iovec iovec[5];
43 char header_priority[6], header_pid[16];
44 int n = 0;
45 char *ident_buf = NULL;
46
47 assert(s);
48 assert(priority >= 0);
49 assert(priority <= 999);
50 assert(message);
51
52 if (_unlikely_(LOG_PRI(priority) > s->max_level_kmsg))
53 return;
54
55 if (_unlikely_(s->dev_kmsg_fd < 0))
56 return;
57
58 /* Never allow messages with kernel facility to be written to
59 * kmsg, regardless where the data comes from. */
60 priority = syslog_fixup_facility(priority);
61
62 /* First: priority field */
63 snprintf(header_priority, sizeof(header_priority), "<%i>", priority);
64 char_array_0(header_priority);
65 IOVEC_SET_STRING(iovec[n++], header_priority);
66
67 /* Second: identifier and PID */
68 if (ucred) {
69 if (!identifier) {
70 get_process_comm(ucred->pid, &ident_buf);
71 identifier = ident_buf;
72 }
73
74 snprintf(header_pid, sizeof(header_pid), "["PID_FMT"]: ", ucred->pid);
75 char_array_0(header_pid);
76
77 if (identifier)
78 IOVEC_SET_STRING(iovec[n++], identifier);
79
80 IOVEC_SET_STRING(iovec[n++], header_pid);
81 } else if (identifier) {
82 IOVEC_SET_STRING(iovec[n++], identifier);
83 IOVEC_SET_STRING(iovec[n++], ": ");
84 }
85
86 /* Fourth: message */
87 IOVEC_SET_STRING(iovec[n++], message);
88 IOVEC_SET_STRING(iovec[n++], "\n");
89
90 if (writev(s->dev_kmsg_fd, iovec, n) < 0)
91 log_debug("Failed to write to /dev/kmsg for logging: %m");
92
93 free(ident_buf);
94 }
95
96 static bool is_us(const char *pid) {
97 pid_t t;
98
99 assert(pid);
100
101 if (parse_pid(pid, &t) < 0)
102 return false;
103
104 return t == getpid();
105 }
106
107 static void dev_kmsg_record(Server *s, char *p, size_t l) {
108 struct iovec iovec[N_IOVEC_META_FIELDS + 7 + N_IOVEC_KERNEL_FIELDS + 2 + N_IOVEC_UDEV_FIELDS];
109 char *message = NULL, *syslog_priority = NULL, *syslog_pid = NULL, *syslog_facility = NULL, *syslog_identifier = NULL, *source_time = NULL;
110 int priority, r;
111 unsigned n = 0, z = 0, j;
112 unsigned long long usec;
113 char *identifier = NULL, *pid = NULL, *e, *f, *k;
114 uint64_t serial;
115 size_t pl;
116 char *kernel_device = NULL;
117
118 assert(s);
119 assert(p);
120
121 if (l <= 0)
122 return;
123
124 e = memchr(p, ',', l);
125 if (!e)
126 return;
127 *e = 0;
128
129 r = safe_atoi(p, &priority);
130 if (r < 0 || priority < 0 || priority > 999)
131 return;
132
133 if (s->forward_to_kmsg && (priority & LOG_FACMASK) != LOG_KERN)
134 return;
135
136 l -= (e - p) + 1;
137 p = e + 1;
138 e = memchr(p, ',', l);
139 if (!e)
140 return;
141 *e = 0;
142
143 r = safe_atou64(p, &serial);
144 if (r < 0)
145 return;
146
147 if (s->kernel_seqnum) {
148 /* We already read this one? */
149 if (serial < *s->kernel_seqnum)
150 return;
151
152 /* Did we lose any? */
153 if (serial > *s->kernel_seqnum)
154 server_driver_message(s, SD_MESSAGE_JOURNAL_MISSED, "Missed %"PRIu64" kernel messages",
155 serial - *s->kernel_seqnum - 1);
156
157 /* Make sure we never read this one again. Note that
158 * we always store the next message serial we expect
159 * here, simply because this makes handling the first
160 * message with serial 0 easy. */
161 *s->kernel_seqnum = serial + 1;
162 }
163
164 l -= (e - p) + 1;
165 p = e + 1;
166 f = memchr(p, ';', l);
167 if (!f)
168 return;
169 /* Kernel 3.6 has the flags field, kernel 3.5 lacks that */
170 e = memchr(p, ',', l);
171 if (!e || f < e)
172 e = f;
173 *e = 0;
174
175 r = safe_atollu(p, &usec);
176 if (r < 0)
177 return;
178
179 l -= (f - p) + 1;
180 p = f + 1;
181 e = memchr(p, '\n', l);
182 if (!e)
183 return;
184 *e = 0;
185
186 pl = e - p;
187 l -= (e - p) + 1;
188 k = e + 1;
189
190 for (j = 0; l > 0 && j < N_IOVEC_KERNEL_FIELDS; j++) {
191 char *m;
192 /* Meta data fields attached */
193
194 if (*k != ' ')
195 break;
196
197 k ++, l --;
198
199 e = memchr(k, '\n', l);
200 if (!e)
201 return;
202
203 *e = 0;
204
205 m = cunescape_length_with_prefix(k, e - k, "_KERNEL_");
206 if (!m)
207 break;
208
209 if (startswith(m, "_KERNEL_DEVICE="))
210 kernel_device = m + 15;
211
212 IOVEC_SET_STRING(iovec[n++], m);
213 z++;
214
215 l -= (e - k) + 1;
216 k = e + 1;
217 }
218
219 if (kernel_device) {
220 struct udev_device *ud;
221
222 ud = udev_device_new_from_device_id(s->udev, kernel_device);
223 if (ud) {
224 const char *g;
225 struct udev_list_entry *ll;
226 char *b;
227
228 g = udev_device_get_devnode(ud);
229 if (g) {
230 b = strappend("_UDEV_DEVNODE=", g);
231 if (b) {
232 IOVEC_SET_STRING(iovec[n++], b);
233 z++;
234 }
235 }
236
237 g = udev_device_get_sysname(ud);
238 if (g) {
239 b = strappend("_UDEV_SYSNAME=", g);
240 if (b) {
241 IOVEC_SET_STRING(iovec[n++], b);
242 z++;
243 }
244 }
245
246 j = 0;
247 ll = udev_device_get_devlinks_list_entry(ud);
248 udev_list_entry_foreach(ll, ll) {
249
250 if (j > N_IOVEC_UDEV_FIELDS)
251 break;
252
253 g = udev_list_entry_get_name(ll);
254 if (g) {
255 b = strappend("_UDEV_DEVLINK=", g);
256 if (b) {
257 IOVEC_SET_STRING(iovec[n++], b);
258 z++;
259 }
260 }
261
262 j++;
263 }
264
265 udev_device_unref(ud);
266 }
267 }
268
269 if (asprintf(&source_time, "_SOURCE_MONOTONIC_TIMESTAMP=%llu", usec) >= 0)
270 IOVEC_SET_STRING(iovec[n++], source_time);
271
272 IOVEC_SET_STRING(iovec[n++], "_TRANSPORT=kernel");
273
274 if (asprintf(&syslog_priority, "PRIORITY=%i", priority & LOG_PRIMASK) >= 0)
275 IOVEC_SET_STRING(iovec[n++], syslog_priority);
276
277 if (asprintf(&syslog_facility, "SYSLOG_FACILITY=%i", LOG_FAC(priority)) >= 0)
278 IOVEC_SET_STRING(iovec[n++], syslog_facility);
279
280 if ((priority & LOG_FACMASK) == LOG_KERN)
281 IOVEC_SET_STRING(iovec[n++], "SYSLOG_IDENTIFIER=kernel");
282 else {
283 pl -= syslog_parse_identifier((const char**) &p, &identifier, &pid);
284
285 /* Avoid any messages we generated ourselves via
286 * log_info() and friends. */
287 if (pid && is_us(pid))
288 goto finish;
289
290 if (identifier) {
291 syslog_identifier = strappend("SYSLOG_IDENTIFIER=", identifier);
292 if (syslog_identifier)
293 IOVEC_SET_STRING(iovec[n++], syslog_identifier);
294 }
295
296 if (pid) {
297 syslog_pid = strappend("SYSLOG_PID=", pid);
298 if (syslog_pid)
299 IOVEC_SET_STRING(iovec[n++], syslog_pid);
300 }
301 }
302
303 message = cunescape_length_with_prefix(p, pl, "MESSAGE=");
304 if (message)
305 IOVEC_SET_STRING(iovec[n++], message);
306
307 server_dispatch_message(s, iovec, n, ELEMENTSOF(iovec), NULL, NULL, NULL, 0, NULL, priority, 0);
308
309 finish:
310 for (j = 0; j < z; j++)
311 free(iovec[j].iov_base);
312
313 free(message);
314 free(syslog_priority);
315 free(syslog_identifier);
316 free(syslog_pid);
317 free(syslog_facility);
318 free(source_time);
319 free(identifier);
320 free(pid);
321 }
322
323 static int server_read_dev_kmsg(Server *s) {
324 char buffer[8192+1]; /* the kernel-side limit per record is 8K currently */
325 ssize_t l;
326
327 assert(s);
328 assert(s->dev_kmsg_fd >= 0);
329
330 l = read(s->dev_kmsg_fd, buffer, sizeof(buffer) - 1);
331 if (l == 0)
332 return 0;
333 if (l < 0) {
334 /* Old kernels who don't allow reading from /dev/kmsg
335 * return EINVAL when we try. So handle this cleanly,
336 * but don' try to ever read from it again. */
337 if (errno == EINVAL) {
338 s->dev_kmsg_event_source = sd_event_source_unref(s->dev_kmsg_event_source);
339 return 0;
340 }
341
342 if (errno == EAGAIN || errno == EINTR || errno == EPIPE)
343 return 0;
344
345 log_error("Failed to read from kernel: %m");
346 return -errno;
347 }
348
349 dev_kmsg_record(s, buffer, l);
350 return 1;
351 }
352
353 int server_flush_dev_kmsg(Server *s) {
354 int r;
355
356 assert(s);
357
358 if (s->dev_kmsg_fd < 0)
359 return 0;
360
361 if (!s->dev_kmsg_readable)
362 return 0;
363
364 log_debug("Flushing /dev/kmsg...");
365
366 for (;;) {
367 r = server_read_dev_kmsg(s);
368 if (r < 0)
369 return r;
370
371 if (r == 0)
372 break;
373 }
374
375 return 0;
376 }
377
378 static int dispatch_dev_kmsg(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
379 Server *s = userdata;
380
381 assert(es);
382 assert(fd == s->dev_kmsg_fd);
383 assert(s);
384
385 if (revents & EPOLLERR)
386 log_warning("/dev/kmsg buffer overrun, some messages lost.");
387
388 if (!(revents & EPOLLIN))
389 log_error("Got invalid event from epoll for /dev/kmsg: %"PRIx32, revents);
390
391 return server_read_dev_kmsg(s);
392 }
393
394 int server_open_dev_kmsg(Server *s) {
395 int r;
396
397 assert(s);
398
399 s->dev_kmsg_fd = open("/dev/kmsg", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
400 if (s->dev_kmsg_fd < 0) {
401 log_full(errno == ENOENT ? LOG_DEBUG : LOG_WARNING,
402 "Failed to open /dev/kmsg, ignoring: %m");
403 return 0;
404 }
405
406 r = sd_event_add_io(s->event, &s->dev_kmsg_event_source, s->dev_kmsg_fd, EPOLLIN, dispatch_dev_kmsg, s);
407 if (r < 0) {
408
409 /* This will fail with EPERM on older kernels where
410 * /dev/kmsg is not readable. */
411 if (r == -EPERM) {
412 r = 0;
413 goto fail;
414 }
415
416 log_error("Failed to add /dev/kmsg fd to event loop: %s", strerror(-r));
417 goto fail;
418 }
419
420 r = sd_event_source_set_priority(s->dev_kmsg_event_source, SD_EVENT_PRIORITY_IMPORTANT+10);
421 if (r < 0) {
422 log_error("Failed to adjust priority of kmsg event source: %s", strerror(-r));
423 goto fail;
424 }
425
426 s->dev_kmsg_readable = true;
427
428 return 0;
429
430 fail:
431 s->dev_kmsg_event_source = sd_event_source_unref(s->dev_kmsg_event_source);
432 s->dev_kmsg_fd = safe_close(s->dev_kmsg_fd);
433
434 return r;
435 }
436
437 int server_open_kernel_seqnum(Server *s) {
438 _cleanup_close_ int fd;
439 uint64_t *p;
440
441 assert(s);
442
443 /* We store the seqnum we last read in an mmaped file. That
444 * way we can just use it like a variable, but it is
445 * persistent and automatically flushed at reboot. */
446
447 fd = open("/run/systemd/journal/kernel-seqnum", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0644);
448 if (fd < 0) {
449 log_error("Failed to open /run/systemd/journal/kernel-seqnum, ignoring: %m");
450 return 0;
451 }
452
453 if (posix_fallocate(fd, 0, sizeof(uint64_t)) < 0) {
454 log_error("Failed to allocate sequential number file, ignoring: %m");
455 return 0;
456 }
457
458 p = mmap(NULL, sizeof(uint64_t), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
459 if (p == MAP_FAILED) {
460 log_error("Failed to map sequential number file, ignoring: %m");
461 return 0;
462 }
463
464 s->kernel_seqnum = p;
465
466 return 0;
467 }