Line data Source code
1 : /* Quagga signal handling functions.
2 : * Copyright (C) 2004 Paul Jakma,
3 : *
4 : * This file is part of Quagga.
5 : *
6 : * Quagga is free software; you can redistribute it and/or modify it
7 : * under the terms of the GNU General Public License as published by the
8 : * Free Software Foundation; either version 2, or (at your option) any
9 : * later version.
10 : *
11 : * Quagga is distributed in the hope that it will be useful, but
12 : * WITHOUT ANY WARRANTY; without even the implied warranty of
13 : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 : * General Public License for more details.
15 : *
16 : * You should have received a copy of the GNU General Public License along
17 : * with this program; see the file COPYING; if not, write to the Free Software
18 : * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 : */
20 :
21 : #include <zebra.h>
22 : #include <sigevent.h>
23 : #include <log.h>
24 : #include <memory.h>
25 : #include <lib_errors.h>
26 :
27 : #ifdef HAVE_UCONTEXT_H
28 : #ifdef GNU_LINUX
29 : /* get REG_EIP from ucontext.h */
30 : #ifndef __USE_GNU
31 : #define __USE_GNU
32 : #endif /* __USE_GNU */
33 : #endif /* GNU_LINUX */
34 : #include <ucontext.h>
35 : #endif /* HAVE_UCONTEXT_H */
36 :
37 :
38 : /* master signals descriptor struct */
39 : static struct frr_sigevent_master_t {
40 : struct thread *t;
41 :
42 : struct frr_signal_t *signals;
43 : int sigc;
44 :
45 : volatile sig_atomic_t caught;
46 : } sigmaster;
47 :
48 : /* Generic signal handler
49 : * Schedules signal event thread
50 : */
51 3 : static void frr_signal_handler(int signo)
52 : {
53 3 : int i;
54 3 : struct frr_signal_t *sig;
55 :
56 15 : for (i = 0; i < sigmaster.sigc; i++) {
57 12 : sig = &(sigmaster.signals[i]);
58 :
59 12 : if (sig->signal == signo)
60 3 : sig->caught = 1;
61 : }
62 :
63 3 : sigmaster.caught = 1;
64 3 : }
65 :
66 : /*
67 : * Check whether any signals have been received and are pending. This is done
68 : * with the application's key signals blocked. The complete set of signals
69 : * is returned in 'setp', so the caller can restore them when appropriate.
70 : * If there are pending signals, returns 'true', 'false' otherwise.
71 : */
72 2126 : bool frr_sigevent_check(sigset_t *setp)
73 : {
74 2126 : sigset_t blocked;
75 2126 : int i;
76 2126 : bool ret;
77 :
78 2126 : sigemptyset(setp);
79 2126 : sigemptyset(&blocked);
80 :
81 : /* Set up mask of application's signals */
82 12756 : for (i = 0; i < sigmaster.sigc; i++)
83 8504 : sigaddset(&blocked, sigmaster.signals[i].signal);
84 :
85 2126 : pthread_sigmask(SIG_BLOCK, &blocked, setp);
86 :
87 : /* Now that the application's signals are blocked, test. */
88 2126 : ret = (sigmaster.caught != 0);
89 :
90 2126 : return ret;
91 : }
92 :
93 : /* check if signals have been caught and run appropriate handlers */
94 2321 : int frr_sigevent_process(void)
95 : {
96 2321 : struct frr_signal_t *sig;
97 2321 : int i;
98 : #ifdef SIGEVENT_BLOCK_SIGNALS
99 : /* shouldn't need to block signals, but potentially may be needed */
100 : sigset_t newmask, oldmask;
101 :
102 : /*
103 : * Block most signals, but be careful not to defer SIGTRAP because
104 : * doing so breaks gdb, at least on NetBSD 2.0. Avoid asking to
105 : * block SIGKILL, just because we shouldn't be able to do so.
106 : */
107 : sigfillset(&newmask);
108 : sigdelset(&newmask, SIGTRAP);
109 : sigdelset(&newmask, SIGKILL);
110 :
111 : if ((sigprocmask(SIG_BLOCK, &newmask, &oldmask)) < 0) {
112 : flog_err_sys(EC_LIB_SYSTEM_CALL,
113 : "frr_signal_timer: couldnt block signals!");
114 : return -1;
115 : }
116 : #endif /* SIGEVENT_BLOCK_SIGNALS */
117 :
118 2321 : if (sigmaster.caught > 0) {
119 3 : sigmaster.caught = 0;
120 : /* must not read or set sigmaster.caught after here,
121 : * race condition with per-sig caught flags if one does
122 : */
123 :
124 13 : for (i = 0; i < sigmaster.sigc; i++) {
125 12 : sig = &(sigmaster.signals[i]);
126 :
127 12 : if (sig->caught > 0) {
128 3 : sig->caught = 0;
129 3 : if (sig->handler)
130 3 : sig->handler();
131 : }
132 : }
133 : }
134 :
135 : #ifdef SIGEVENT_BLOCK_SIGNALS
136 : if (sigprocmask(SIG_UNBLOCK, &oldmask, NULL) < 0)
137 : return -1;
138 : #endif /* SIGEVENT_BLOCK_SIGNALS */
139 :
140 2319 : return 0;
141 : }
142 :
143 : #ifdef SIGEVENT_SCHEDULE_THREAD
144 : /* timer thread to check signals. shouldn't be needed */
145 : void frr_signal_timer(struct thread *t)
146 : {
147 : struct frr_sigevent_master_t *sigm;
148 :
149 : sigm = THREAD_ARG(t);
150 : sigm->t = NULL;
151 : thread_add_timer(sigm->t->master, frr_signal_timer, &sigmaster,
152 : FRR_SIGNAL_TIMER_INTERVAL, &sigm->t);
153 : frr_sigevent_process();
154 : }
155 : #endif /* SIGEVENT_SCHEDULE_THREAD */
156 :
157 : /* Initialization of signal handles. */
158 : /* Signal wrapper. */
159 12 : static int signal_set(int signo)
160 : {
161 12 : int ret;
162 12 : struct sigaction sig;
163 12 : struct sigaction osig;
164 :
165 12 : sig.sa_handler = &frr_signal_handler;
166 12 : sigfillset(&sig.sa_mask);
167 12 : sig.sa_flags = 0;
168 12 : if (signo == SIGALRM) {
169 : #ifdef SA_INTERRUPT
170 0 : sig.sa_flags |= SA_INTERRUPT; /* SunOS */
171 : #endif
172 : } else {
173 : #ifdef SA_RESTART
174 12 : sig.sa_flags |= SA_RESTART;
175 : #endif /* SA_RESTART */
176 : }
177 :
178 12 : ret = sigaction(signo, &sig, &osig);
179 12 : if (ret < 0)
180 : return ret;
181 : else
182 12 : return 0;
183 : }
184 :
185 : /* XXX This function should be enhanced to support more platforms
186 : (it currently works only on Linux/x86). */
187 0 : static void *program_counter(void *context)
188 : {
189 : #ifdef HAVE_UCONTEXT_H
190 : #ifdef GNU_LINUX
191 : /* these are from GNU libc, rather than Linux, strictly speaking */
192 : #if defined(REG_EIP)
193 : # define REG_INDEX REG_EIP
194 : #elif defined(REG_RIP)
195 : # define REG_INDEX REG_RIP
196 : #elif defined(__powerpc__)
197 : # define REG_INDEX 32
198 : #endif
199 : #endif /* GNU_LINUX */
200 :
201 : #ifdef REG_INDEX
202 : #ifdef HAVE_UCONTEXT_T_UC_MCONTEXT_GREGS
203 : # define REGS gregs[REG_INDEX]
204 : #elif defined(HAVE_UCONTEXT_T_UC_MCONTEXT_UC_REGS)
205 : # define REGS uc_regs->gregs[REG_INDEX]
206 : #endif /* HAVE_UCONTEXT_T_UC_MCONTEXT_GREGS */
207 : #endif /* REG_INDEX */
208 :
209 : #ifdef REGS
210 0 : if (context)
211 0 : return (void *)(((ucontext_t *)context)->uc_mcontext.REGS);
212 : #elif defined(HAVE_UCONTEXT_T_UC_MCONTEXT_REGS__NIP)
213 : /* older Linux / struct pt_regs ? */
214 : if (context)
215 : return (void *)(((ucontext_t *)context)->uc_mcontext.regs->nip);
216 : #endif /* REGS */
217 :
218 : #endif /* HAVE_UCONTEXT_H */
219 : return NULL;
220 : }
221 :
222 : static void __attribute__((noreturn))
223 0 : exit_handler(int signo, siginfo_t *siginfo, void *context)
224 : {
225 0 : void *pc = program_counter(context);
226 :
227 0 : zlog_signal(signo, "exiting...", siginfo, pc);
228 0 : _exit(128 + signo);
229 : }
230 :
231 : static void __attribute__((noreturn))
232 0 : core_handler(int signo, siginfo_t *siginfo, void *context)
233 : {
234 0 : void *pc = program_counter(context);
235 :
236 : /* make sure we don't hang in here. default for SIGALRM is terminate.
237 : * - if we're in backtrace for more than a second, abort. */
238 0 : struct sigaction sa_default = {.sa_handler = SIG_DFL};
239 :
240 0 : sigaction(SIGALRM, &sa_default, NULL);
241 0 : sigaction(signo, &sa_default, NULL);
242 :
243 0 : sigset_t sigset;
244 :
245 0 : sigemptyset(&sigset);
246 0 : sigaddset(&sigset, SIGALRM);
247 0 : sigprocmask(SIG_UNBLOCK, &sigset, NULL);
248 :
249 0 : alarm(1);
250 :
251 0 : zlog_signal(signo, "aborting...", siginfo, pc);
252 :
253 : /* dump memory stats on core */
254 0 : log_memstats(stderr, "core_handler");
255 :
256 0 : zlog_tls_buffer_fini();
257 :
258 : /* give the kernel a chance to generate a coredump */
259 0 : sigaddset(&sigset, signo);
260 0 : sigprocmask(SIG_UNBLOCK, &sigset, NULL);
261 0 : raise(signo);
262 :
263 : /* only chance to end up here is if the default action for signo is
264 : * something other than kill or coredump the process
265 : */
266 0 : _exit(128 + signo);
267 : }
268 :
269 3 : static void trap_default_signals(void)
270 : {
271 3 : static const int core_signals[] = {
272 : SIGQUIT, SIGILL, SIGABRT,
273 : #ifdef SIGEMT
274 : SIGEMT,
275 : #endif
276 : SIGFPE, SIGBUS, SIGSEGV,
277 : #ifdef SIGSYS
278 : SIGSYS,
279 : #endif
280 : #ifdef SIGXCPU
281 : SIGXCPU,
282 : #endif
283 : #ifdef SIGXFSZ
284 : SIGXFSZ,
285 : #endif
286 : };
287 3 : static const int exit_signals[] = {
288 : SIGHUP, SIGINT, SIGALRM, SIGTERM, SIGUSR1, SIGUSR2,
289 : #ifdef SIGPOLL
290 : SIGPOLL,
291 : #endif
292 : #ifdef SIGVTALRM
293 : SIGVTALRM,
294 : #endif
295 : #ifdef SIGSTKFLT
296 : SIGSTKFLT,
297 : #endif
298 : };
299 3 : static const int ignore_signals[] = {
300 : SIGPIPE,
301 : };
302 3 : static const struct {
303 : const int *sigs;
304 : unsigned int nsigs;
305 : void (*handler)(int signo, siginfo_t *info, void *context);
306 : } sigmap[] = {
307 : {core_signals, array_size(core_signals), core_handler},
308 : {exit_signals, array_size(exit_signals), exit_handler},
309 : {ignore_signals, array_size(ignore_signals), NULL},
310 : };
311 3 : unsigned int i;
312 :
313 12 : for (i = 0; i < array_size(sigmap); i++) {
314 : unsigned int j;
315 :
316 66 : for (j = 0; j < sigmap[i].nsigs; j++) {
317 57 : struct sigaction oact;
318 57 : if ((sigaction(sigmap[i].sigs[j], NULL, &oact) == 0)
319 57 : && (oact.sa_handler == SIG_DFL)) {
320 57 : struct sigaction act;
321 57 : sigfillset(&act.sa_mask);
322 57 : if (sigmap[i].handler == NULL) {
323 3 : act.sa_handler = SIG_IGN;
324 3 : act.sa_flags = 0;
325 : } else {
326 : /* Request extra arguments to signal
327 : * handler. */
328 54 : act.sa_sigaction = sigmap[i].handler;
329 54 : act.sa_flags = SA_SIGINFO;
330 : #ifdef SA_RESETHAND
331 : /* don't try to print backtraces
332 : * recursively */
333 54 : if (sigmap[i].handler == core_handler)
334 27 : act.sa_flags |= SA_RESETHAND;
335 : #endif
336 : }
337 57 : if (sigaction(sigmap[i].sigs[j], &act, NULL)
338 : < 0)
339 57 : flog_err(
340 : EC_LIB_SYSTEM_CALL,
341 : "Unable to set signal handler for signal %d: %s",
342 : sigmap[i].sigs[j],
343 : safe_strerror(errno));
344 : }
345 : }
346 : }
347 3 : }
348 :
349 3 : void signal_init(struct thread_master *m, int sigc,
350 : struct frr_signal_t signals[])
351 : {
352 :
353 3 : int i = 0;
354 3 : struct frr_signal_t *sig;
355 :
356 : /* First establish some default handlers that can be overridden by
357 : the application. */
358 3 : trap_default_signals();
359 :
360 15 : while (i < sigc) {
361 12 : sig = &signals[i];
362 12 : if (signal_set(sig->signal) < 0)
363 0 : exit(-1);
364 12 : i++;
365 : }
366 :
367 3 : sigmaster.sigc = sigc;
368 3 : sigmaster.signals = signals;
369 :
370 : #ifdef SIGEVENT_SCHEDULE_THREAD
371 : sigmaster.t = NULL;
372 : thread_add_timer(m, frr_signal_timer, &sigmaster,
373 : FRR_SIGNAL_TIMER_INTERVAL, &sigmaster.t);
374 : #endif /* SIGEVENT_SCHEDULE_THREAD */
375 3 : }
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