1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 #include <time.h>
27 #include <stdio.h>
28 #include <assert.h>
29 #include <string.h>
30 #include <stdlib.h>
31 #include <unistd.h>
32 #include <sys/types.h>
33 #include <sys/wait.h>
34 #include <signal.h>
35 #include <fcntl.h>
36 #include <dhcpmsg.h>
37
38 #include "agent.h"
39 #include "script_handler.h"
40 #include "states.h"
41 #include "interface.h"
42
43 /*
44 * scripts are directly managed by a script helper process. dhcpagent creates
45 * the helper process and it, in turn, creates a process to run the script
46 * dhcpagent owns one end of a pipe and the helper process owns the other end
47 * the helper process calls waitpid to wait for the script to exit. an alarm
48 * is set for SCRIPT_TIMEOUT seconds. If the alarm fires, SIGTERM is sent to
49 * the script process and a second alarm is set for SCRIPT_TIMEOUT_GRACE. if
50 * the second alarm fires, SIGKILL is sent to forcefully kill the script. when
51 * script exits, the helper process notifies dhcpagent by closing its end
52 * of the pipe.
53 */
54
55 unsigned int script_count;
56
57 /*
58 * the signal to send to the script process. it is a global variable
59 * to this file as sigterm_handler needs it.
60 */
61
62 static int script_signal = SIGTERM;
63
64 /*
65 * script's absolute timeout value. the first timeout is set to SCRIPT_TIMEOUT
66 * seconds from the time it is started. SIGTERM is sent on the first timeout
67 * the second timeout is set to SCRIPT_TIMEOUT_GRACE from the first timeout
68 * and SIGKILL is sent on the second timeout.
69 */
70 static time_t timeout;
71
72 /*
73 * sigalarm_handler(): signal handler for SIGALRM
74 *
75 * input: int: signal the handler was called with
76 * output: void
77 */
78
79 /* ARGSUSED */
80 static void
sigalarm_handler(int sig)81 sigalarm_handler(int sig)
82 {
83 time_t now;
84
85 /* set a another alarm if it fires too early */
86 now = time(NULL);
87 if (now < timeout)
88 (void) alarm(timeout - now);
89 }
90
91 /*
92 * sigterm_handler(): signal handler for SIGTERM, fired when dhcpagent wants
93 * to stop the script
94 * input: int: signal the handler was called with
95 * output: void
96 */
97
98 /* ARGSUSED */
99 static void
sigterm_handler(int sig)100 sigterm_handler(int sig)
101 {
102 if (script_signal != SIGKILL) {
103 /* send SIGKILL SCRIPT_TIMEOUT_GRACE seconds from now */
104 script_signal = SIGKILL;
105 timeout = time(NULL) + SCRIPT_TIMEOUT_GRACE;
106 (void) alarm(SCRIPT_TIMEOUT_GRACE);
107 }
108 }
109
110 /*
111 * run_script(): it forks a process to execute the script
112 *
113 * input: dhcp_smach_t *: the state machine
114 * const char *: the event name
115 * int: the pipe end owned by the script helper process
116 * output: void
117 */
118
119 static void
run_script(dhcp_smach_t * dsmp,const char * event,int fd)120 run_script(dhcp_smach_t *dsmp, const char *event, int fd)
121 {
122 int n;
123 char c;
124 char *path;
125 char *name;
126 pid_t pid;
127 time_t now;
128
129 if ((pid = fork()) == -1)
130 return;
131
132 if (pid == 0) {
133 path = SCRIPT_PATH;
134 name = strrchr(path, '/') + 1;
135
136 /* close all files */
137 closefrom(0);
138
139 /* redirect stdin, stdout and stderr to /dev/null */
140 if ((n = open("/dev/null", O_RDWR)) < 0)
141 _exit(127);
142
143 (void) dup2(n, STDOUT_FILENO);
144 (void) dup2(n, STDERR_FILENO);
145 (void) execl(path, name, dsmp->dsm_name, event, NULL);
146 _exit(127);
147 }
148
149 /*
150 * the first timeout fires SCRIPT_TIMEOUT seconds from now.
151 */
152 timeout = time(NULL) + SCRIPT_TIMEOUT;
153 (void) sigset(SIGALRM, sigalarm_handler);
154 (void) alarm(SCRIPT_TIMEOUT);
155
156 /*
157 * pass script's pid to dhcpagent.
158 */
159 (void) write(fd, &pid, sizeof (pid));
160
161 for (;;) {
162 if (waitpid(pid, NULL, 0) >= 0) {
163 /* script has exited */
164 c = SCRIPT_OK;
165 break;
166 }
167
168 if (errno != EINTR)
169 return;
170
171 now = time(NULL);
172 if (now >= timeout) {
173 (void) kill(pid, script_signal);
174 if (script_signal == SIGKILL) {
175 c = SCRIPT_KILLED;
176 break;
177 }
178
179 script_signal = SIGKILL;
180 timeout = now + SCRIPT_TIMEOUT_GRACE;
181 (void) alarm(SCRIPT_TIMEOUT_GRACE);
182 }
183 }
184
185 (void) write(fd, &c, 1);
186 }
187
188 /*
189 * script_init(): initialize script state on a given state machine
190 *
191 * input: dhcp_smach_t *: the state machine
192 * output: void
193 */
194
195 void
script_init(dhcp_smach_t * dsmp)196 script_init(dhcp_smach_t *dsmp)
197 {
198 dsmp->dsm_script_pid = -1;
199 dsmp->dsm_script_helper_pid = -1;
200 dsmp->dsm_script_event_id = -1;
201 dsmp->dsm_script_fd = -1;
202 dsmp->dsm_script_callback = NULL;
203 dsmp->dsm_script_event = NULL;
204 dsmp->dsm_callback_arg = NULL;
205 }
206
207 /*
208 * script_cleanup(): cleanup helper function
209 *
210 * input: dhcp_smach_t *: the state machine
211 * output: void
212 */
213
214 static void
script_cleanup(dhcp_smach_t * dsmp)215 script_cleanup(dhcp_smach_t *dsmp)
216 {
217 /*
218 * We must clear dsm_script_pid prior to invoking the callback or we
219 * could get in an infinite loop via async_finish().
220 */
221 dsmp->dsm_script_pid = -1;
222 dsmp->dsm_script_helper_pid = -1;
223
224 if (dsmp->dsm_script_fd != -1) {
225 assert(dsmp->dsm_script_event_id != -1);
226 (void) iu_unregister_event(eh, dsmp->dsm_script_event_id, NULL);
227 (void) close(dsmp->dsm_script_fd);
228
229 assert(dsmp->dsm_script_callback != NULL);
230 dsmp->dsm_script_callback(dsmp, dsmp->dsm_callback_arg);
231 script_init(dsmp);
232 script_count--;
233 release_smach(dsmp); /* hold from script_start() */
234 }
235 }
236
237 /*
238 * script_exit(): does cleanup and invokes the callback when the script exits
239 *
240 * input: eh_t *: unused
241 * int: the end of pipe owned by dhcpagent
242 * short: unused
243 * eh_event_id_t: unused
244 * void *: the state machine
245 * output: void
246 */
247
248 /* ARGSUSED */
249 static void
script_exit(iu_eh_t * ehp,int fd,short events,iu_event_id_t id,void * arg)250 script_exit(iu_eh_t *ehp, int fd, short events, iu_event_id_t id, void *arg)
251 {
252 char c;
253
254 if (read(fd, &c, 1) <= 0)
255 c = SCRIPT_FAILED;
256
257 if (c == SCRIPT_OK)
258 dhcpmsg(MSG_DEBUG, "script ok");
259 else if (c == SCRIPT_KILLED)
260 dhcpmsg(MSG_DEBUG, "script killed");
261 else
262 dhcpmsg(MSG_DEBUG, "script failed");
263
264 script_cleanup(arg);
265 }
266
267 /*
268 * script_start(): tries to start a script.
269 * if a script is already running, it's stopped first.
270 *
271 *
272 * input: dhcp_smach_t *: the state machine
273 * const char *: the event name
274 * script_callback_t: callback function
275 * void *: data to the callback function
276 * output: boolean_t: B_TRUE if script starts successfully
277 * int *: the returned value of the callback function if script
278 * starts unsuccessfully
279 */
280
281 boolean_t
script_start(dhcp_smach_t * dsmp,const char * event,script_callback_t * callback,void * arg,int * status)282 script_start(dhcp_smach_t *dsmp, const char *event,
283 script_callback_t *callback, void *arg, int *status)
284 {
285 int n;
286 int fds[2];
287 pid_t pid;
288 iu_event_id_t event_id;
289
290 assert(callback != NULL);
291
292 if (dsmp->dsm_script_pid != -1) {
293 /* script is running, stop it */
294 dhcpmsg(MSG_DEBUG, "script_start: stopping ongoing script");
295 script_stop(dsmp);
296 }
297
298 if (access(SCRIPT_PATH, X_OK) == -1) {
299 /* script does not exist */
300 goto out;
301 }
302
303 /*
304 * dhcpagent owns one end of the pipe and script helper process
305 * owns the other end. dhcpagent reads on the pipe; and the helper
306 * process notifies it when the script exits.
307 */
308 if (pipe(fds) < 0) {
309 dhcpmsg(MSG_ERROR, "script_start: can't create pipe");
310 goto out;
311 }
312
313 if ((pid = fork()) < 0) {
314 dhcpmsg(MSG_ERROR, "script_start: can't fork");
315 (void) close(fds[0]);
316 (void) close(fds[1]);
317 goto out;
318 }
319
320 if (pid == 0) {
321 /*
322 * SIGCHLD is ignored in dhcpagent, the helper process
323 * needs it. it calls waitpid to wait for the script to exit.
324 */
325 (void) close(fds[0]);
326 (void) sigset(SIGCHLD, SIG_DFL);
327 (void) sigset(SIGTERM, sigterm_handler);
328 run_script(dsmp, event, fds[1]);
329 exit(0);
330 }
331
332 (void) close(fds[1]);
333
334 /* get the script's pid */
335 if (read(fds[0], &dsmp->dsm_script_pid, sizeof (pid_t)) !=
336 sizeof (pid_t)) {
337 (void) kill(pid, SIGKILL);
338 dsmp->dsm_script_pid = -1;
339 (void) close(fds[0]);
340 goto out;
341 }
342
343 dsmp->dsm_script_helper_pid = pid;
344 event_id = iu_register_event(eh, fds[0], POLLIN, script_exit, dsmp);
345 if (event_id == -1) {
346 (void) close(fds[0]);
347 script_stop(dsmp);
348 goto out;
349 }
350
351 script_count++;
352 dsmp->dsm_script_event_id = event_id;
353 dsmp->dsm_script_callback = callback;
354 dsmp->dsm_script_event = event;
355 dsmp->dsm_callback_arg = arg;
356 dsmp->dsm_script_fd = fds[0];
357 hold_smach(dsmp);
358 return (B_TRUE);
359
360 out:
361 /* callback won't be called in script_exit, so call it here */
362 n = callback(dsmp, arg);
363 if (status != NULL)
364 *status = n;
365
366 return (B_FALSE);
367 }
368
369 /*
370 * script_stop(): stops the script if it is running
371 *
372 * input: dhcp_smach_t *: the state machine
373 * output: void
374 */
375
376 void
script_stop(dhcp_smach_t * dsmp)377 script_stop(dhcp_smach_t *dsmp)
378 {
379 if (dsmp->dsm_script_pid != -1) {
380 assert(dsmp->dsm_script_helper_pid != -1);
381
382 /*
383 * sends SIGTERM to the script and asks the helper process
384 * to send SIGKILL if it does not exit after
385 * SCRIPT_TIMEOUT_GRACE seconds.
386 */
387 (void) kill(dsmp->dsm_script_pid, SIGTERM);
388 (void) kill(dsmp->dsm_script_helper_pid, SIGTERM);
389 }
390
391 script_cleanup(dsmp);
392 }
393