1 /*-
2 * Copyright 2018 Aniket Pandey
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * SUCH DAMAGE.
24 */
25
26 #include <sys/types.h>
27 #include <sys/extattr.h>
28 #include <sys/ioctl.h>
29
30 #include <bsm/libbsm.h>
31 #include <bsm/auditd_lib.h>
32 #include <security/audit/audit_ioctl.h>
33
34 #include <atf-c.h>
35 #include <errno.h>
36 #include <fcntl.h>
37 #include <stdlib.h>
38 #include <string.h>
39 #include <time.h>
40 #include <unistd.h>
41
42 #include "utils.h"
43
44 /*
45 * Checks the presence of "auditregex" in auditpipe(4) after the
46 * corresponding system call has been triggered.
47 */
48 static bool
get_records(const char * auditregex,FILE * pipestream)49 get_records(const char *auditregex, FILE *pipestream)
50 {
51 uint8_t *buff;
52 tokenstr_t token;
53 ssize_t size = 1024;
54 char membuff[size];
55 char del[] = ",";
56 int reclen, bytes = 0;
57 FILE *memstream;
58
59 /*
60 * Open a stream on 'membuff' (address to memory buffer) for storing
61 * the audit records in the default mode.'reclen' is the length of the
62 * available records from auditpipe which is passed to the functions
63 * au_fetch_tok(3) and au_print_flags_tok(3) for further use.
64 */
65 ATF_REQUIRE((memstream = fmemopen(membuff, size, "w")) != NULL);
66 ATF_REQUIRE((reclen = au_read_rec(pipestream, &buff)) != -1);
67
68 /*
69 * Iterate through each BSM token, extracting the bits that are
70 * required to start processing the token sequences.
71 */
72 while (bytes < reclen) {
73 if (au_fetch_tok(&token, buff + bytes, reclen - bytes) == -1) {
74 perror("au_read_rec");
75 atf_tc_fail("Incomplete Audit Record");
76 }
77
78 /* Print the tokens as they are obtained, in the default form */
79 au_print_flags_tok(memstream, &token, del, AU_OFLAG_NONE);
80 fputc(',', memstream);
81 bytes += token.len;
82 }
83
84 free(buff);
85 ATF_REQUIRE_EQ(0, fclose(memstream));
86 return (atf_utils_grep_string("%s", membuff, auditregex));
87 }
88
89 /*
90 * Override the system-wide audit mask settings in /etc/security/audit_control
91 * and set the auditpipe's maximum allowed queue length limit
92 */
93 static void
set_preselect_mode(int filedesc,au_mask_t * fmask)94 set_preselect_mode(int filedesc, au_mask_t *fmask)
95 {
96 int qlimit_max;
97 int fmode = AUDITPIPE_PRESELECT_MODE_LOCAL;
98
99 /* Set local preselection mode for auditing */
100 if (ioctl(filedesc, AUDITPIPE_SET_PRESELECT_MODE, &fmode) < 0)
101 atf_tc_fail("Preselection mode: %s", strerror(errno));
102
103 /* Set local preselection flag corresponding to the audit_event */
104 if (ioctl(filedesc, AUDITPIPE_SET_PRESELECT_FLAGS, fmask) < 0)
105 atf_tc_fail("Preselection flag: %s", strerror(errno));
106
107 /* Set local preselection flag for non-attributable audit_events */
108 if (ioctl(filedesc, AUDITPIPE_SET_PRESELECT_NAFLAGS, fmask) < 0)
109 atf_tc_fail("Preselection naflag: %s", strerror(errno));
110
111 /* Query the maximum possible queue length limit for auditpipe */
112 if (ioctl(filedesc, AUDITPIPE_GET_QLIMIT_MAX, &qlimit_max) < 0)
113 atf_tc_fail("Query max-limit: %s", strerror(errno));
114
115 /* Set the queue length limit as obtained from previous step */
116 if (ioctl(filedesc, AUDITPIPE_SET_QLIMIT, &qlimit_max) < 0)
117 atf_tc_fail("Set max-qlimit: %s", strerror(errno));
118
119 /* This removes any outstanding record on the auditpipe */
120 if (ioctl(filedesc, AUDITPIPE_FLUSH) < 0)
121 atf_tc_fail("Auditpipe flush: %s", strerror(errno));
122 }
123
124 /*
125 * Get the corresponding audit_mask for class-name "name" then set the
126 * success and failure bits for fmask to be used as the ioctl argument
127 */
128 static au_mask_t
get_audit_mask(const char * name)129 get_audit_mask(const char *name)
130 {
131 au_mask_t fmask;
132 au_class_ent_t *class;
133
134 ATF_REQUIRE((class = getauclassnam(name)) != NULL);
135 fmask.am_success = class->ac_class;
136 fmask.am_failure = class->ac_class;
137 return (fmask);
138 }
139
140 /*
141 * Loop until the auditpipe returns something, check if it is what
142 * we want, else repeat the procedure until ppoll(2) times out.
143 */
144 static void
check_auditpipe(struct pollfd fd[],const char * auditregex,FILE * pipestream)145 check_auditpipe(struct pollfd fd[], const char *auditregex, FILE *pipestream)
146 {
147 struct timespec currtime, endtime, timeout;
148
149 /* Set the expire time for poll(2) while waiting for syscall audit */
150 ATF_REQUIRE_EQ(0, clock_gettime(CLOCK_MONOTONIC, &endtime));
151 /* Set limit to 30 seconds total and ~10s without an event. */
152 endtime.tv_sec += 30;
153
154 for (;;) {
155 /* Update the time left for auditpipe to return any event */
156 ATF_REQUIRE_EQ(0, clock_gettime(CLOCK_MONOTONIC, &currtime));
157 timespecsub(&endtime, &currtime, &timeout);
158 timeout.tv_sec = MIN(timeout.tv_sec, 9);
159 if (timeout.tv_sec < 0) {
160 atf_tc_fail("%s not found in auditpipe within the "
161 "time limit", auditregex);
162 }
163
164 switch (ppoll(fd, 1, &timeout, NULL)) {
165 /* ppoll(2) returns, check if it's what we want */
166 case 1:
167 if (fd[0].revents & POLLIN) {
168 if (get_records(auditregex, pipestream))
169 return;
170 } else {
171 atf_tc_fail("Auditpipe returned an "
172 "unknown event %#x", fd[0].revents);
173 }
174 break;
175
176 /* poll(2) timed out */
177 case 0:
178 atf_tc_fail("%s not found in auditpipe within the "
179 "time limit", auditregex);
180 break;
181
182 /* poll(2) standard error */
183 case -1:
184 atf_tc_fail("Poll: %s", strerror(errno));
185 break;
186
187 default:
188 atf_tc_fail("Poll returned too many file descriptors");
189 }
190 }
191 }
192
193 /*
194 * Wrapper functions around static "check_auditpipe"
195 */
196 static void
check_audit_startup(struct pollfd fd[],const char * auditrgx,FILE * pipestream)197 check_audit_startup(struct pollfd fd[], const char *auditrgx, FILE *pipestream){
198 check_auditpipe(fd, auditrgx, pipestream);
199 }
200
201 void
check_audit(struct pollfd fd[],const char * auditrgx,FILE * pipestream)202 check_audit(struct pollfd fd[], const char *auditrgx, FILE *pipestream) {
203 check_auditpipe(fd, auditrgx, pipestream);
204
205 /* Teardown: /dev/auditpipe's instance opened for this test-suite */
206 ATF_REQUIRE_EQ(0, fclose(pipestream));
207 }
208
209 void
skip_if_extattr_not_supported(const char * path)210 skip_if_extattr_not_supported(const char *path)
211 {
212 ssize_t result;
213
214 /*
215 * Some file systems (e.g. tmpfs) do not support extattr, so we need
216 * skip tests that use extattrs. To detect this we can check whether
217 * the extattr_list_file returns EOPNOTSUPP.
218 */
219 result = extattr_list_file(path, EXTATTR_NAMESPACE_USER, NULL, 0);
220 if (result == -1 && errno == EOPNOTSUPP) {
221 atf_tc_skip("File system does not support extattrs.");
222 }
223 }
224
225 static bool
is_auditd_running(void)226 is_auditd_running(void)
227 {
228 int trigger;
229 int err;
230
231 /*
232 * AUDIT_TRIGGER_INITIALIZE is a no-op message on FreeBSD and can
233 * therefore be used to check whether auditd has already been started.
234 * This is significantly cheaper than running `service auditd onestatus`
235 * for each test case. It is also slightly less racy since it will only
236 * return true once auditd() has opened the trigger file rather than
237 * just when the pidfile has been created.
238 */
239 trigger = AUDIT_TRIGGER_INITIALIZE;
240 err = auditon(A_SENDTRIGGER, &trigger, sizeof(trigger));
241 if (err == 0) {
242 fprintf(stderr, "auditd(8) is running.\n");
243 return (true);
244 } else {
245 /*
246 * A_SENDTRIGGER returns ENODEV if auditd isn't listening,
247 * all other error codes indicate a fatal error.
248 */
249 ATF_REQUIRE_MSG(errno == ENODEV,
250 "Unexpected error from auditon(2): %s", strerror(errno));
251 return (false);
252 }
253
254 }
255
256 FILE *
setup(struct pollfd fd[],const char * name)257 setup(struct pollfd fd[], const char *name)
258 {
259 au_mask_t fmask, nomask;
260 FILE *pipestream;
261 fmask = get_audit_mask(name);
262 nomask = get_audit_mask("no");
263
264 ATF_REQUIRE((fd[0].fd = open("/dev/auditpipe", O_RDONLY)) != -1);
265 ATF_REQUIRE((pipestream = fdopen(fd[0].fd, "r")) != NULL);
266 fd[0].events = POLLIN;
267
268 /*
269 * Disable stream buffering for read operations from /dev/auditpipe.
270 * Otherwise it is possible that fread(3), called via au_read_rec(3),
271 * can store buffered data in user-space unbeknown to ppoll(2), which
272 * as a result, reports that /dev/auditpipe is empty.
273 */
274 ATF_REQUIRE_EQ(0, setvbuf(pipestream, NULL, _IONBF, 0));
275
276 /* Set local preselection audit_class as "no" for audit startup */
277 set_preselect_mode(fd[0].fd, &nomask);
278 if (!is_auditd_running()) {
279 fprintf(stderr, "Running audit_quick_start() for testing... ");
280 /*
281 * Previously, this test started auditd using
282 * `service auditd onestart`. However, there is a race condition
283 * there since service can return before auditd(8) has
284 * fully started (once the daemon parent process has forked)
285 * and this can cause check_audit_startup() to fail sometimes.
286 *
287 * In the CheriBSD CI this caused the first test executed by
288 * kyua (administrative:acct_failure) to fail every time, but
289 * subsequent ones would almost always succeed.
290 *
291 * To avoid this problem (and as a nice side-effect this speeds
292 * up the test quite a bit), we register this process as a
293 * "fake" auditd(8) using the audit_quick_start() function from
294 * libauditd.
295 */
296 atf_utils_create_file("started_fake_auditd", "yes\n");
297 ATF_REQUIRE(atf_utils_file_exists("started_fake_auditd"));
298 ATF_REQUIRE_EQ_MSG(0, audit_quick_start(),
299 "Failed to start fake auditd: %m");
300 fprintf(stderr, "done.\n");
301 /* audit_quick_start() should log an audit start event. */
302 check_audit_startup(fd, "audit startup", pipestream);
303 /*
304 * If we exit cleanly shutdown audit_quick_start(), if not
305 * cleanup() will take care of it.
306 * This is not required, but makes it easier to run individual
307 * tests outside of kyua.
308 */
309 atexit(cleanup);
310 }
311
312 /* Set local preselection parameters specific to "name" audit_class */
313 set_preselect_mode(fd[0].fd, &fmask);
314 return (pipestream);
315 }
316
317 void
cleanup(void)318 cleanup(void)
319 {
320 if (atf_utils_file_exists("started_fake_auditd")) {
321 fprintf(stderr, "Running audit_quick_stop()... ");
322 if (audit_quick_stop() != 0) {
323 fprintf(stderr, "Failed to stop fake auditd: %m\n");
324 abort();
325 }
326 fprintf(stderr, "done.\n");
327 unlink("started_fake_auditd");
328 }
329 }
330