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 occuring 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 thos occuring 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 log_debug_errno(r, "Failed to parse audit array: %m");
324 r = map_generic_field(prefix, &p, iov, n_iov_allocated, n_iov);
326 log_debug_errno(r, "Failed to parse audit array: %m");
331 /* Couldn't process as generic field, let's just skip over it */
332 p += strcspn(p, WHITESPACE);
338 static void process_audit_string(Server *s, int type, const char *data, size_t size) {
339 _cleanup_free_ struct iovec *iov = NULL;
340 size_t n_iov_allocated = 0;
341 unsigned n_iov = 0, k;
342 uint64_t seconds, msec, id;
345 char id_field[sizeof("_AUDIT_ID=") + DECIMAL_STR_MAX(uint64_t)],
346 type_field[sizeof("_AUDIT_TYPE=") + DECIMAL_STR_MAX(int)],
347 source_time_field[sizeof("_SOURCE_REALTIME_TIMESTAMP=") + DECIMAL_STR_MAX(usec_t)];
358 /* Note that the input buffer is NUL terminated, but let's
359 * check whether there is a spurious NUL byte */
360 if (memchr(data, 0, size))
363 p = startswith(data, "audit");
367 if (sscanf(p, "(%" PRIi64 ".%" PRIi64 ":%" PRIi64 "):%n",
375 p += strspn(p, WHITESPACE);
380 n_iov_allocated = N_IOVEC_META_FIELDS + 5;
381 iov = new(struct iovec, n_iov_allocated);
387 IOVEC_SET_STRING(iov[n_iov++], "_TRANSPORT=audit");
389 sprintf(source_time_field, "_SOURCE_REALTIME_TIMESTAMP=%" PRIu64,
390 (usec_t) seconds * USEC_PER_SEC + (usec_t) msec * USEC_PER_MSEC);
391 IOVEC_SET_STRING(iov[n_iov++], source_time_field);
393 sprintf(type_field, "_AUDIT_TYPE=%i", type);
394 IOVEC_SET_STRING(iov[n_iov++], type_field);
396 sprintf(id_field, "_AUDIT_ID=%" PRIu64, id);
397 IOVEC_SET_STRING(iov[n_iov++], id_field);
399 m = alloca(strlen("MESSAGE=<audit-") + DECIMAL_STR_MAX(int) + strlen("> ") + strlen(p) + 1);
400 sprintf(m, "MESSAGE=<audit-%i> %s", type, p);
401 IOVEC_SET_STRING(iov[n_iov++], m);
405 map_all_fields(p, map_fields_kernel, "_AUDIT_FIELD_", true, &iov, &n_iov_allocated, &n_iov);
407 if (!GREEDY_REALLOC(iov, n_iov_allocated, n_iov + N_IOVEC_META_FIELDS)) {
412 server_dispatch_message(s, iov, n_iov, n_iov_allocated, NULL, NULL, NULL, 0, NULL, LOG_NOTICE, 0);
415 /* free() all entries that map_all_fields() added. All others
416 * are allocated on the stack or are constant. */
418 for (; z < n_iov; z++)
419 free(iov[z].iov_base);
422 void server_process_audit_message(
426 const struct ucred *ucred,
427 const union sockaddr_union *sa,
430 const struct nlmsghdr *nl = buffer;
434 if (buffer_size < ALIGN(sizeof(struct nlmsghdr)))
439 /* Filter out fake data */
441 salen != sizeof(struct sockaddr_nl) ||
442 sa->nl.nl_family != AF_NETLINK ||
443 sa->nl.nl_pid != 0) {
444 log_debug("Audit netlink message from invalid sender.");
448 if (!ucred || ucred->pid != 0) {
449 log_debug("Audit netlink message with invalid credentials.");
453 if (!NLMSG_OK(nl, buffer_size)) {
454 log_error("Audit netlink message truncated.");
458 /* Ignore special Netlink messages */
459 if (IN_SET(nl->nlmsg_type, NLMSG_NOOP, NLMSG_ERROR))
462 /* Below AUDIT_FIRST_USER_MSG theer are only control messages, let's ignore those */
463 if (nl->nlmsg_type < AUDIT_FIRST_USER_MSG)
466 process_audit_string(s, nl->nlmsg_type, NLMSG_DATA(nl), nl->nlmsg_len - ALIGN(sizeof(struct nlmsghdr)));
469 static int enable_audit(int fd, bool b) {
472 struct nlmsghdr header;
473 uint8_t header_space[NLMSG_HDRLEN];
475 struct audit_status body;
476 } _packed_ request = {
477 .header.nlmsg_len = NLMSG_LENGTH(sizeof(struct audit_status)),
478 .header.nlmsg_type = AUDIT_SET,
479 .header.nlmsg_flags = NLM_F_REQUEST,
480 .header.nlmsg_seq = 1,
481 .header.nlmsg_pid = 0,
482 .body.mask = AUDIT_STATUS_ENABLED,
485 union sockaddr_union sa = {
486 .nl.nl_family = AF_NETLINK,
489 struct iovec iovec = {
490 .iov_base = &request,
491 .iov_len = NLMSG_LENGTH(sizeof(struct audit_status)),
497 .msg_namelen = sizeof(sa.nl),
502 n = sendmsg(fd, &mh, MSG_NOSIGNAL);
505 if (n != NLMSG_LENGTH(sizeof(struct audit_status)))
508 /* We don't wait for the result here, we can't do anything
514 int server_open_audit(Server *s) {
515 static const int one = 1;
518 if (s->audit_fd < 0) {
519 static const union sockaddr_union sa = {
520 .nl.nl_family = AF_NETLINK,
522 .nl.nl_groups = AUDIT_NLGRP_READLOG,
525 s->audit_fd = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_AUDIT);
526 if (s->audit_fd < 0) {
527 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
528 log_debug("Audit not supported in the kernel.");
530 log_warning("Failed to create audit socket, ignoring: %m");
535 r = bind(s->audit_fd, &sa.sa, sizeof(sa.nl));
537 log_error("Failed to join audit multicast group: %m");
541 fd_nonblock(s->audit_fd, 1);
543 r = setsockopt(s->audit_fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one));
545 log_error("Failed to set SO_PASSCRED on audit socket: %m");
549 r = sd_event_add_io(s->event, &s->audit_event_source, s->audit_fd, EPOLLIN, process_datagram, s);
551 log_error_errno(r, "Failed to add audit fd to event loop: %m");
555 /* We are listening now, try to enable audit */
556 r = enable_audit(s->audit_fd, true);
558 log_warning_errno(r, "Failed to issue audit enable call: %m");