Line data Source code
1 : /*
2 : Unix SMB/CIFS implementation.
3 : Critical Fault handling
4 : Copyright (C) Andrew Tridgell 1992-1998
5 : Copyright (C) Tim Prouty 2009
6 : Copyright (C) James Peach 2006
7 :
8 : This program is free software; you can redistribute it and/or modify
9 : it under the terms of the GNU General Public License as published by
10 : the Free Software Foundation; either version 3 of the License, or
11 : (at your option) any later version.
12 :
13 : This program is distributed in the hope that it will be useful,
14 : but WITHOUT ANY WARRANTY; without even the implied warranty of
15 : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 : GNU General Public License for more details.
17 :
18 : You should have received a copy of the GNU General Public License
19 : along with this program. If not, see <http://www.gnu.org/licenses/>.
20 : */
21 :
22 : #include "replace.h"
23 : #include "system/filesys.h"
24 : #include "system/wait.h"
25 : #include "version.h"
26 :
27 : #ifdef HAVE_SYS_SYSCTL_H
28 : #include <sys/sysctl.h>
29 : #endif
30 :
31 :
32 : #ifdef HAVE_SYS_PRCTL_H
33 : #include <sys/prctl.h>
34 : #endif
35 :
36 : #include "debug.h"
37 : #include "lib/util/signal.h" /* Avoid /usr/include/signal.h */
38 : #include "fault.h"
39 :
40 : static struct {
41 : bool disabled;
42 : smb_panic_handler_t panic_handler;
43 : } fault_state;
44 :
45 :
46 : /*******************************************************************
47 : setup variables used for fault handling
48 : ********************************************************************/
49 8370 : void fault_configure(smb_panic_handler_t panic_handler)
50 : {
51 8370 : fault_state.panic_handler = panic_handler;
52 8370 : }
53 :
54 :
55 : /**
56 : disable setting up fault handlers
57 : This is used for the bind9 dlz module, as we
58 : don't want a Samba module in bind9 to override the bind
59 : fault handling
60 : **/
61 15 : _PUBLIC_ void fault_setup_disable(void)
62 : {
63 15 : fault_state.disabled = true;
64 15 : }
65 :
66 :
67 : #if !defined(HAVE_DISABLE_FAULT_HANDLING)
68 : /*******************************************************************
69 : report a fault
70 : ********************************************************************/
71 0 : static void fault_report(int sig)
72 : {
73 : static int counter;
74 : char signal_string[128];
75 :
76 0 : if (counter) _exit(1);
77 :
78 0 : counter++;
79 :
80 0 : snprintf(signal_string, sizeof(signal_string),
81 : "Signal %d: %s", sig, strsignal(sig));
82 0 : smb_panic(signal_string);
83 :
84 : /* smb_panic() never returns, so this is really redundant */
85 : exit(1);
86 : }
87 :
88 : /****************************************************************************
89 : catch serious errors
90 : ****************************************************************************/
91 0 : static void sig_fault(int sig)
92 : {
93 0 : fault_report(sig);
94 0 : }
95 : #endif
96 : /*******************************************************************
97 : setup our fault handlers
98 : ********************************************************************/
99 13590 : void fault_setup(void)
100 : {
101 13590 : if (fault_state.disabled) {
102 0 : return;
103 : }
104 : #if !defined(HAVE_DISABLE_FAULT_HANDLING)
105 : #ifdef SIGSEGV
106 13590 : CatchSignal(SIGSEGV, sig_fault);
107 : #endif
108 : #ifdef SIGBUS
109 13590 : CatchSignal(SIGBUS, sig_fault);
110 : #endif
111 : #ifdef SIGABRT
112 13590 : CatchSignal(SIGABRT, sig_fault);
113 : #endif
114 : #endif
115 : }
116 :
117 : _PUBLIC_ const char *panic_action = NULL;
118 :
119 : /*
120 : default smb_panic() implementation
121 : */
122 : static void smb_panic_default(const char *why) _NORETURN_;
123 0 : static void smb_panic_default(const char *why)
124 : {
125 : #if defined(HAVE_PRCTL) && defined(PR_SET_PTRACER)
126 : /*
127 : * Make sure all children can attach a debugger.
128 : */
129 0 : prctl(PR_SET_PTRACER, getpid(), 0, 0, 0);
130 : #endif
131 :
132 0 : if (panic_action && *panic_action) {
133 : char cmdstring[200];
134 0 : if (strlcpy(cmdstring, panic_action, sizeof(cmdstring)) < sizeof(cmdstring)) {
135 : int result;
136 : char pidstr[20];
137 : char subst[200];
138 0 : char *p = NULL;
139 0 : snprintf(pidstr, sizeof(pidstr), "%d", (int) getpid());
140 :
141 0 : p = strstr(cmdstring, "%d");
142 0 : if (p != NULL) {
143 0 : snprintf(subst,
144 : sizeof(subst),
145 : "%.*s%s%s",
146 0 : (int)(p-cmdstring),
147 : cmdstring,
148 : pidstr,
149 : p+2);
150 0 : strlcpy(cmdstring, subst, sizeof(cmdstring));
151 : }
152 :
153 0 : DEBUG(0, ("smb_panic(): calling panic action [%s]\n", cmdstring));
154 0 : result = system(cmdstring);
155 :
156 0 : if (result == -1)
157 0 : DEBUG(0, ("smb_panic(): fork failed in panic action: %s\n",
158 : strerror(errno)));
159 : else
160 0 : DEBUG(0, ("smb_panic(): action returned status %d\n",
161 : WEXITSTATUS(result)));
162 : }
163 : }
164 :
165 : #ifdef SIGABRT
166 0 : CatchSignal(SIGABRT, SIG_DFL);
167 : #endif
168 0 : abort();
169 : }
170 :
171 0 : _PUBLIC_ void smb_panic_log(const char *why)
172 : {
173 0 : DEBUGSEP(0);
174 0 : DEBUG(0,("INTERNAL ERROR: %s in pid %lld (%s)\n",
175 : why,
176 : (unsigned long long)getpid(),
177 : SAMBA_VERSION_STRING));
178 0 : DEBUG(0,("If you are running a recent Samba version, and "
179 : "if you think this problem is not yet fixed in the "
180 : "latest versions, please consider reporting this "
181 : "bug, see "
182 : "https://wiki.samba.org/index.php/Bug_Reporting\n"));
183 0 : DEBUGSEP(0);
184 0 : DEBUG(0,("PANIC (pid %llu): %s in " SAMBA_VERSION_STRING "\n",
185 : (unsigned long long)getpid(), why));
186 :
187 0 : log_stack_trace();
188 0 : }
189 :
190 : /**
191 : Something really nasty happened - panic !
192 : **/
193 0 : _PUBLIC_ void smb_panic(const char *why)
194 : {
195 0 : smb_panic_log(why);
196 :
197 0 : if (fault_state.panic_handler) {
198 0 : fault_state.panic_handler(why);
199 0 : _exit(1);
200 : }
201 0 : smb_panic_default(why);
202 : }
203 :
204 : /*******************************************************************
205 : Print a backtrace of the stack to the debug log. This function
206 : DELIBERATELY LEAKS MEMORY. The expectation is that you should
207 : exit shortly after calling it.
208 : ********************************************************************/
209 :
210 : /* Buffer size to use when printing backtraces */
211 : #define BACKTRACE_STACK_SIZE 64
212 :
213 :
214 : #ifdef HAVE_LIBUNWIND_H
215 : #include <libunwind.h>
216 : #endif
217 :
218 : #ifdef HAVE_EXECINFO_H
219 : #include <execinfo.h>
220 : #endif
221 :
222 0 : void log_stack_trace(void)
223 : {
224 : #ifdef HAVE_LIBUNWIND
225 : /*
226 : * --with-libunwind is required to use libunwind, the
227 : * backtrace_symbols() code below is the default.
228 : *
229 : * This code is available because a previous version of this
230 : * comment asserted that on ia64 libunwind correctly walks the
231 : * stack in more circumstances than backtrace.
232 : */
233 : unw_cursor_t cursor;
234 : unw_context_t uc;
235 : unsigned i = 0;
236 :
237 : char procname[256];
238 : unw_word_t ip, sp, off;
239 :
240 : procname[sizeof(procname) - 1] = '\0';
241 :
242 : if (unw_getcontext(&uc) != 0) {
243 : goto libunwind_failed;
244 : }
245 :
246 : if (unw_init_local(&cursor, &uc) != 0) {
247 : goto libunwind_failed;
248 : }
249 :
250 : DEBUG(0, ("BACKTRACE:\n"));
251 :
252 : do {
253 : ip = sp = 0;
254 : unw_get_reg(&cursor, UNW_REG_IP, &ip);
255 : unw_get_reg(&cursor, UNW_REG_SP, &sp);
256 :
257 : switch (unw_get_proc_name(&cursor,
258 : procname, sizeof(procname) - 1, &off) ) {
259 : case 0:
260 : /* Name found. */
261 : case -UNW_ENOMEM:
262 : /* Name truncated. */
263 : DEBUGADD(0, (" #%u %s + %#llx [ip=%#llx] [sp=%#llx]\n",
264 : i, procname, (long long)off,
265 : (long long)ip, (long long) sp));
266 : break;
267 : default:
268 : /* case -UNW_ENOINFO: */
269 : /* case -UNW_EUNSPEC: */
270 : /* No symbol name found. */
271 : DEBUGADD(0, (" #%u %s [ip=%#llx] [sp=%#llx]\n",
272 : i, "<unknown symbol>",
273 : (long long)ip, (long long) sp));
274 : }
275 : ++i;
276 : } while (unw_step(&cursor) > 0);
277 :
278 : return;
279 :
280 : libunwind_failed:
281 : DEBUG(0, ("unable to produce a stack trace with libunwind\n"));
282 :
283 : #elif defined(HAVE_BACKTRACE_SYMBOLS)
284 : void *backtrace_stack[BACKTRACE_STACK_SIZE];
285 : size_t backtrace_size;
286 : char **backtrace_strings;
287 :
288 : /* get the backtrace (stack frames) */
289 0 : backtrace_size = backtrace(backtrace_stack,BACKTRACE_STACK_SIZE);
290 0 : backtrace_strings = backtrace_symbols(backtrace_stack, backtrace_size);
291 :
292 0 : DEBUG(0, ("BACKTRACE: %lu stack frames:\n",
293 : (unsigned long)backtrace_size));
294 :
295 0 : if (backtrace_strings) {
296 : size_t i;
297 :
298 0 : for (i = 0; i < backtrace_size; i++)
299 0 : DEBUGADD(0, (" #%zu %s\n", i, backtrace_strings[i]));
300 :
301 : /* Leak the backtrace_strings, rather than risk what free() might do */
302 : }
303 :
304 : #else
305 : DEBUG(0, ("unable to produce a stack trace on this platform\n"));
306 : #endif
307 0 : }
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