lib/util/fault.c

   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 #include "util_process.h"
  40
  41 static struct {
  42         bool disabled;
  43         smb_panic_handler_t panic_handler;
  44 } fault_state;
  45
  46
  47 /*******************************************************************
  48 setup variables used for fault handling
  49 ********************************************************************/
  50 void fault_configure(smb_panic_handler_t panic_handler)
  51 {
  52         fault_state.panic_handler = panic_handler;
  53 }
  54
  55
  56 /**
  57    disable setting up fault handlers
  58    This is used for the bind9 dlz module, as we
  59    don't want a Samba module in bind9 to override the bind
  60    fault handling
  61 **/
  62 _PUBLIC_ void fault_setup_disable(void)
  63 {
  64         fault_state.disabled = true;
  65 }
  66
  67
  68 #if !defined(HAVE_DISABLE_FAULT_HANDLING)
  69 /*******************************************************************
  70 report a fault
  71 ********************************************************************/
  72 static void fault_report(int sig)
  73 {
  74         static int counter;
  75         char signal_string[128];
  76
  77         if (counter) _exit(1);
  78
  79         counter++;
  80
  81         snprintf(signal_string, sizeof(signal_string),
  82                  "Signal %d: %s", sig, strsignal(sig));
  83         smb_panic(signal_string);
  84
  85         /* smb_panic() never returns, so this is really redundant */
  86         exit(1);
  87 }
  88
  89 /****************************************************************************
  90 catch serious errors
  91 ****************************************************************************/
  92 static void sig_fault(int sig)
  93 {
  94         fault_report(sig);
  95 }
  96 #endif
  97 /*******************************************************************
  98 setup our fault handlers
  99 ********************************************************************/
 100 void fault_setup(void)
 101 {
 102         if (fault_state.disabled) {
 103                 return;
 104         }
 105 #if !defined(HAVE_DISABLE_FAULT_HANDLING)
 106 #ifdef SIGSEGV
 107         CatchSignal(SIGSEGV, sig_fault);
 108 #endif
 109 #ifdef SIGBUS
 110         CatchSignal(SIGBUS, sig_fault);
 111 #endif
 112 #ifdef SIGABRT
 113         CatchSignal(SIGABRT, sig_fault);
 114 #endif
 115 #endif
 116 }
 117
 118 _PUBLIC_ const char *panic_action = NULL;
 119
 120 /*
 121    default smb_panic() implementation
 122 */
 123 static void smb_panic_default(const char *why) _NORETURN_;
 124 static void smb_panic_default(const char *why)
 125 {
 126 #if defined(HAVE_PRCTL) && defined(PR_SET_PTRACER)
 127         /*
 128          * Make sure all children can attach a debugger.
 129          */
 130         prctl(PR_SET_PTRACER, getpid(), 0, 0, 0);
 131 #endif
 132
 133         if (panic_action && *panic_action) {
 134                 char cmdstring[200];
 135                 if (strlcpy(cmdstring, panic_action, sizeof(cmdstring)) < sizeof(cmdstring)) {
 136                         int result;
 137                         char pidstr[20];
 138                         char subst[200];
 139                         char *p = NULL;
 140                         snprintf(pidstr, sizeof(pidstr), "%d", (int) getpid());
 141
 142                         p = strstr(cmdstring, "%d");
 143                         if (p != NULL) {
 144                                 snprintf(subst,
 145                                          sizeof(subst),
 146                                          "%.*s%s%s",
 147                                          (int)(p-cmdstring),
 148                                          cmdstring,
 149                                          pidstr,
 150                                          p+2);
 151                                 strlcpy(cmdstring, subst, sizeof(cmdstring));
 152                         }
 153
 154                         DEBUG(0, ("smb_panic(): calling panic action [%s]\n", cmdstring));
 155                         result = system(cmdstring);
 156
 157                         if (result == -1)
 158                                 DEBUG(0, ("smb_panic(): fork failed in panic action: %s\n",
 159                                           strerror(errno)));
 160                         else
 161                                 DEBUG(0, ("smb_panic(): action returned status %d\n",
 162                                           WEXITSTATUS(result)));
 163                 }
 164         }
 165
 166 #ifdef SIGABRT
 167         CatchSignal(SIGABRT, SIG_DFL);
 168 #endif
 169         abort();
 170 }
 171
 172 _PUBLIC_ void smb_panic_log(const char *why)
 173 {
 174         const char *binary_name = process_get_saved_binary_name();
 175         const char *short_title = process_get_short_title();
 176         const char *long_title = process_get_long_title();
 177
 178         DEBUGSEP(0);
 179         DEBUG(0,("INTERNAL ERROR: %s in %s (%s) (%s) pid %lld (%s)\n",
 180                  why,
 181                  binary_name,
 182                  short_title,
 183                  long_title,
 184                  (unsigned long long)getpid(),
 185                  SAMBA_VERSION_STRING));
 186         DEBUG(0,("If you are running a recent Samba version, and "
 187                  "if you think this problem is not yet fixed in the "
 188                  "latest versions, please consider reporting this "
 189                  "bug, see "
 190                  "https://wiki.samba.org/index.php/Bug_Reporting\n"));
 191         DEBUGSEP(0);
 192         DEBUG(0,("PANIC (pid %llu): %s in " SAMBA_VERSION_STRING "\n",
 193                  (unsigned long long)getpid(), why));
 194
 195         log_stack_trace();
 196 }
 197
 198 /**
 199    Something really nasty happened - panic !
 200
 201    This function is in this file to allow sharing the last set process
 202    title into the logs before the backtrace
 203 **/
 204 _PUBLIC_ void smb_panic(const char *why)
 205 {
 206         smb_panic_log(why);
 207
 208         if (fault_state.panic_handler) {
 209                 fault_state.panic_handler(why);
 210                 _exit(1);
 211         }
 212         smb_panic_default(why);
 213 }
 214
 215 /*******************************************************************
 216  Print a backtrace of the stack to the debug log. This function
 217  DELIBERATELY LEAKS MEMORY. The expectation is that you should
 218  exit shortly after calling it.
 219 ********************************************************************/
 220
 221 /* Buffer size to use when printing backtraces */
 222 #define BACKTRACE_STACK_SIZE 64
 223
 224
 225 #ifdef HAVE_LIBUNWIND_H
 226 #include <libunwind.h>
 227 #endif
 228
 229 #ifdef HAVE_EXECINFO_H
 230 #include <execinfo.h>
 231 #endif
 232
 233 void log_stack_trace(void)
 234 {
 235 #ifdef HAVE_LIBUNWIND
 236         /*
 237          * --with-libunwind is required to use libunwind, the
 238          * backtrace_symbols() code below is the default.
 239          *
 240          * This code is available because a previous version of this
 241          * comment asserted that on ia64 libunwind correctly walks the
 242          * stack in more circumstances than backtrace.
 243          */
 244         unw_cursor_t cursor;
 245         unw_context_t uc;
 246         unsigned i = 0;
 247
 248         char procname[256];
 249         unw_word_t ip, sp, off;
 250
 251         procname[sizeof(procname) - 1] = '\0';
 252
 253         if (unw_getcontext(&uc) != 0) {
 254                 goto libunwind_failed;
 255         }
 256
 257         if (unw_init_local(&cursor, &uc) != 0) {
 258                 goto libunwind_failed;
 259         }
 260
 261         DEBUG(0, ("BACKTRACE:\n"));
 262
 263         do {
 264             ip = sp = 0;
 265             unw_get_reg(&cursor, UNW_REG_IP, &ip);
 266             unw_get_reg(&cursor, UNW_REG_SP, &sp);
 267
 268             switch (unw_get_proc_name(&cursor,
 269                         procname, sizeof(procname) - 1, &off) ) {
 270             case 0:
 271                     /* Name found. */
 272             case -UNW_ENOMEM:
 273                     /* Name truncated. */
 274                     DEBUGADD(0, (" #%u %s + %#llx [ip=%#llx] [sp=%#llx]\n",
 275                             i, procname, (long long)off,
 276                             (long long)ip, (long long) sp));
 277                     break;
 278             default:
 279             /* case -UNW_ENOINFO: */
 280             /* case -UNW_EUNSPEC: */
 281                     /* No symbol name found. */
 282                     DEBUGADD(0, (" #%u %s [ip=%#llx] [sp=%#llx]\n",
 283                             i, "<unknown symbol>",
 284                             (long long)ip, (long long) sp));
 285             }
 286             ++i;
 287         } while (unw_step(&cursor) > 0);
 288
 289         return;
 290
 291 libunwind_failed:
 292         DEBUG(0, ("unable to produce a stack trace with libunwind\n"));
 293
 294 #elif defined(HAVE_BACKTRACE_SYMBOLS)
 295         void *backtrace_stack[BACKTRACE_STACK_SIZE];
 296         size_t backtrace_size;
 297         char **backtrace_strings;
 298
 299         /* get the backtrace (stack frames) */
 300         backtrace_size = backtrace(backtrace_stack,BACKTRACE_STACK_SIZE);
 301         backtrace_strings = backtrace_symbols(backtrace_stack, backtrace_size);
 302
 303         DEBUG(0, ("BACKTRACE: %lu stack frames:\n",
 304                   (unsigned long)backtrace_size));
 305
 306         if (backtrace_strings) {
 307                 size_t i;
 308
 309                 for (i = 0; i < backtrace_size; i++)
 310                         DEBUGADD(0, (" #%zu %s\n", i, backtrace_strings[i]));
 311
 312                 /* Leak the backtrace_strings, rather than risk what free() might do */
 313         }
 314
 315 #else
 316         DEBUG(0, ("unable to produce a stack trace on this platform\n"));
 317 #endif
 318 }