1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2014 Lennart Poettering
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.
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.
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/>.
23 #include "journald-audit.h"
25 typedef struct MapField {
26 const char *audit_field;
27 const char *journal_field;
28 int (*map)(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, unsigned *n_iov);
31 static int map_simple_field(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, unsigned *n_iov) {
32 _cleanup_free_ char *c = NULL;
33 size_t l = 0, allocated = 0;
43 c = malloc(allocated);
48 for (e = *p; *e != ' ' && *e != 0; e++) {
49 if (!GREEDY_REALLOC(c, allocated, l+2))
57 if (!GREEDY_REALLOC(*iov, *n_iov_allocated, *n_iov + 1))
60 (*iov)[*n_iov].iov_base = c;
61 (*iov)[*n_iov].iov_len = l;
70 static int map_string_field_internal(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, unsigned *n_iov, bool filter_printable) {
71 _cleanup_free_ char *c = NULL;
80 /* The kernel formats string fields in one of two formats. */
83 /* Normal quoted syntax */
89 l = strlen(field) + (e - s);
94 *((char*) mempcpy(stpcpy(c, field), s, e - s)) = 0;
98 } else if (unhexchar(**p) >= 0) {
99 /* Hexadecimal escaping */
100 size_t allocated = 0;
104 c = malloc(allocated);
109 for (e = *p; *e != ' ' && *e != 0; e += 2) {
121 x = ((uint8_t) a << 4 | (uint8_t) b);
123 if (filter_printable && x < (uint8_t) ' ')
126 if (!GREEDY_REALLOC(c, allocated, l+2))
136 if (!GREEDY_REALLOC(*iov, *n_iov_allocated, *n_iov + 1))
139 (*iov)[*n_iov].iov_base = c;
140 (*iov)[*n_iov].iov_len = l;
149 static int map_string_field(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, unsigned *n_iov) {
150 return map_string_field_internal(field, p, iov, n_iov_allocated, n_iov, false);
153 static int map_string_field_printable(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, unsigned *n_iov) {
154 return map_string_field_internal(field, p, iov, n_iov_allocated, n_iov, true);
157 static int map_generic_field(const char *prefix, const char **p, struct iovec **iov, size_t *n_iov_allocated, unsigned *n_iov) {
162 /* Implements fallback mappings for all fields we don't know */
164 for (e = *p; e < *p + 16; e++) {
166 if (*e == 0 || *e == ' ')
172 if (!((*e >= 'a' && *e <= 'z') ||
173 (*e >= 'A' && *e <= 'Z') ||
174 (*e >= '0' && *e <= '9') ||
175 *e == '_' || *e == '-'))
179 if (e <= *p || e >= *p + 16)
182 c = alloca(strlen(prefix) + (e - *p) + 2);
184 t = stpcpy(c, prefix);
185 for (f = *p; f < e; f++) {
188 if (*f >= 'a' && *f <= 'z')
189 x = (*f - 'a') + 'A'; /* uppercase */
191 x = '_'; /* dashes → underscores */
201 r = map_simple_field(c, &e, iov, n_iov_allocated, n_iov);
209 /* Kernel fields are those occurring in the audit string before
210 * msg='. All of these fields are trusted, hence carry the "_" prefix.
211 * We try to translate the fields we know into our native names. The
212 * other's are generically mapped to _AUDIT_FIELD_XYZ= */
213 static const MapField map_fields_kernel[] = {
215 /* First, we map certain well-known audit fields into native
216 * well-known fields */
217 { "pid=", "_PID=", map_simple_field },
218 { "ppid=", "_PPID=", map_simple_field },
219 { "uid=", "_UID=", map_simple_field },
220 { "euid=", "_EUID=", map_simple_field },
221 { "fsuid=", "_FSUID=", map_simple_field },
222 { "gid=", "_GID=", map_simple_field },
223 { "egid=", "_EGID=", map_simple_field },
224 { "fsgid=", "_FSGID=", map_simple_field },
225 { "tty=", "_TTY=", map_simple_field },
226 { "ses=", "_AUDIT_SESSION=", map_simple_field },
227 { "auid=", "_AUDIT_LOGINUID=", map_simple_field },
228 { "subj=", "_SELINUX_CONTEXT=", map_simple_field },
229 { "comm=", "_COMM=", map_string_field },
230 { "exe=", "_EXE=", map_string_field },
231 { "proctitle=", "_CMDLINE=", map_string_field_printable },
233 /* Some fields don't map to native well-known fields. However,
234 * we know that they are string fields, hence let's undo
235 * string field escaping for them, though we stick to the
236 * generic field names. */
237 { "path=", "_AUDIT_FIELD_PATH=", map_string_field },
238 { "dev=", "_AUDIT_FIELD_DEV=", map_string_field },
239 { "name=", "_AUDIT_FIELD_NAME=", map_string_field },
243 /* Userspace fields are those occurring in the audit string after
244 * msg='. All of these fields are untrusted, hence carry no "_"
245 * prefix. We map the fields we don't know to AUDIT_FIELD_XYZ= */
246 static const MapField map_fields_userspace[] = {
247 { "cwd=", "AUDIT_FIELD_CWD=", map_string_field },
248 { "cmd=", "AUDIT_FIELD_CMD=", map_string_field },
249 { "acct=", "AUDIT_FIELD_ACCT=", map_string_field },
250 { "exe=", "AUDIT_FIELD_EXE=", map_string_field },
251 { "comm=", "AUDIT_FIELD_COMM=", map_string_field },
255 static int map_all_fields(
257 const MapField map_fields[],
261 size_t *n_iov_allocated,
268 assert(n_iov_allocated);
276 p += strspn(p, WHITESPACE);
282 v = startswith(p, "msg='");
287 /* Userspace message. It's enclosed in
288 simple quotation marks, is not
289 escaped, but the last field in the
290 line, hence let's remove the
291 quotation mark, and apply the
292 userspace mapping instead of the
295 e = endswith(v, "'");
297 return 0; /* don't continue splitting up if the final quotation mark is missing */
299 c = strndupa(v, e - v);
300 return map_all_fields(c, map_fields_userspace, "AUDIT_FIELD_", false, iov, n_iov_allocated, n_iov);
304 /* Try to map the kernel fields to our own names */
305 for (m = map_fields; m->audit_field; m++) {
306 v = startswith(p, m->audit_field);
310 r = m->map(m->journal_field, &v, iov, n_iov_allocated, n_iov);
312 return log_debug_errno(r, "Failed to parse audit array: %m");
322 r = map_generic_field(prefix, &p, iov, n_iov_allocated, n_iov);
324 return log_debug_errno(r, "Failed to parse audit array: %m");
327 /* Couldn't process as generic field, let's just skip over it */
328 p += strcspn(p, WHITESPACE);
334 static void process_audit_string(Server *s, int type, const char *data, size_t size) {
335 _cleanup_free_ struct iovec *iov = NULL;
336 size_t n_iov_allocated = 0;
337 unsigned n_iov = 0, k;
338 uint64_t seconds, msec, id;
341 char id_field[sizeof("_AUDIT_ID=") + DECIMAL_STR_MAX(uint64_t)],
342 type_field[sizeof("_AUDIT_TYPE=") + DECIMAL_STR_MAX(int)],
343 source_time_field[sizeof("_SOURCE_REALTIME_TIMESTAMP=") + DECIMAL_STR_MAX(usec_t)];
354 /* Note that the input buffer is NUL terminated, but let's
355 * check whether there is a spurious NUL byte */
356 if (memchr(data, 0, size))
359 p = startswith(data, "audit");
363 if (sscanf(p, "(%" PRIu64 ".%" PRIu64 ":%" PRIu64 "):%n",
371 p += strspn(p, WHITESPACE);
376 n_iov_allocated = N_IOVEC_META_FIELDS + 5;
377 iov = new(struct iovec, n_iov_allocated);
383 IOVEC_SET_STRING(iov[n_iov++], "_TRANSPORT=audit");
385 sprintf(source_time_field, "_SOURCE_REALTIME_TIMESTAMP=%" PRIu64,
386 (usec_t) seconds * USEC_PER_SEC + (usec_t) msec * USEC_PER_MSEC);
387 IOVEC_SET_STRING(iov[n_iov++], source_time_field);
389 sprintf(type_field, "_AUDIT_TYPE=%i", type);
390 IOVEC_SET_STRING(iov[n_iov++], type_field);
392 sprintf(id_field, "_AUDIT_ID=%" PRIu64, id);
393 IOVEC_SET_STRING(iov[n_iov++], id_field);
395 m = alloca(strlen("MESSAGE=<audit-") + DECIMAL_STR_MAX(int) + strlen("> ") + strlen(p) + 1);
396 sprintf(m, "MESSAGE=<audit-%i> %s", type, p);
397 IOVEC_SET_STRING(iov[n_iov++], m);
401 map_all_fields(p, map_fields_kernel, "_AUDIT_FIELD_", true, &iov, &n_iov_allocated, &n_iov);
403 if (!GREEDY_REALLOC(iov, n_iov_allocated, n_iov + N_IOVEC_META_FIELDS)) {
408 server_dispatch_message(s, iov, n_iov, n_iov_allocated, NULL, NULL, NULL, 0, NULL, LOG_NOTICE, 0);
411 /* free() all entries that map_all_fields() added. All others
412 * are allocated on the stack or are constant. */
414 for (; z < n_iov; z++)
415 free(iov[z].iov_base);
418 void server_process_audit_message(
422 const struct ucred *ucred,
423 const union sockaddr_union *sa,
426 const struct nlmsghdr *nl = buffer;
430 if (buffer_size < ALIGN(sizeof(struct nlmsghdr)))
435 /* Filter out fake data */
437 salen != sizeof(struct sockaddr_nl) ||
438 sa->nl.nl_family != AF_NETLINK ||
439 sa->nl.nl_pid != 0) {
440 log_debug("Audit netlink message from invalid sender.");
444 if (!ucred || ucred->pid != 0) {
445 log_debug("Audit netlink message with invalid credentials.");
449 if (!NLMSG_OK(nl, buffer_size)) {
450 log_error("Audit netlink message truncated.");
454 /* Ignore special Netlink messages */
455 if (IN_SET(nl->nlmsg_type, NLMSG_NOOP, NLMSG_ERROR))
458 /* Below AUDIT_FIRST_USER_MSG theer are only control messages, let's ignore those */
459 if (nl->nlmsg_type < AUDIT_FIRST_USER_MSG)
462 process_audit_string(s, nl->nlmsg_type, NLMSG_DATA(nl), nl->nlmsg_len - ALIGN(sizeof(struct nlmsghdr)));
465 static int enable_audit(int fd, bool b) {
468 struct nlmsghdr header;
469 uint8_t header_space[NLMSG_HDRLEN];
471 struct audit_status body;
472 } _packed_ request = {
473 .header.nlmsg_len = NLMSG_LENGTH(sizeof(struct audit_status)),
474 .header.nlmsg_type = AUDIT_SET,
475 .header.nlmsg_flags = NLM_F_REQUEST,
476 .header.nlmsg_seq = 1,
477 .header.nlmsg_pid = 0,
478 .body.mask = AUDIT_STATUS_ENABLED,
481 union sockaddr_union sa = {
482 .nl.nl_family = AF_NETLINK,
485 struct iovec iovec = {
486 .iov_base = &request,
487 .iov_len = NLMSG_LENGTH(sizeof(struct audit_status)),
493 .msg_namelen = sizeof(sa.nl),
498 n = sendmsg(fd, &mh, MSG_NOSIGNAL);
501 if (n != NLMSG_LENGTH(sizeof(struct audit_status)))
504 /* We don't wait for the result here, we can't do anything
510 int server_open_audit(Server *s) {
511 static const int one = 1;
514 if (s->audit_fd < 0) {
515 static const union sockaddr_union sa = {
516 .nl.nl_family = AF_NETLINK,
518 .nl.nl_groups = AUDIT_NLGRP_READLOG,
521 s->audit_fd = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_AUDIT);
522 if (s->audit_fd < 0) {
523 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
524 log_debug("Audit not supported in the kernel.");
526 log_warning_errno(errno, "Failed to create audit socket, ignoring: %m");
531 r = bind(s->audit_fd, &sa.sa, sizeof(sa.nl));
533 return log_error_errno(errno, "Failed to join audit multicast group: %m");
535 fd_nonblock(s->audit_fd, 1);
537 r = setsockopt(s->audit_fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one));
539 return log_error_errno(errno, "Failed to set SO_PASSCRED on audit socket: %m");
541 r = sd_event_add_io(s->event, &s->audit_event_source, s->audit_fd, EPOLLIN, server_process_datagram, s);
543 return log_error_errno(r, "Failed to add audit fd to event loop: %m");
545 /* We are listening now, try to enable audit */
546 r = enable_audit(s->audit_fd, true);
548 log_warning_errno(r, "Failed to issue audit enable call: %m");