source3/lib/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
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "includes.h"
  22 #include "system/filesys.h"
  23
  24 #ifdef HAVE_SYS_SYSCTL_H
  25 #include <sys/sysctl.h>
  26 #endif
  27
  28
  29 #ifdef HAVE_SYS_PRCTL_H
  30 #include <sys/prctl.h>
  31 #endif
  32
  33 static void (*cont_fn)(void *);
  34 static char *corepath;
  35
  36 /*******************************************************************
  37 report a fault
  38 ********************************************************************/
  39 static void fault_report(int sig)
  40 {
  41         static int counter;
  42
  43         if (counter) _exit(1);
  44
  45         counter++;
  46
  47         DEBUGSEP(0);
  48         DEBUG(0,("INTERNAL ERROR: Signal %d in pid %d (%s)",sig,(int)sys_getpid(),samba_version_string()));
  49         DEBUG(0,("\nPlease read the Trouble-Shooting section of the Samba3-HOWTO\n"));
  50         DEBUG(0,("\nFrom: http://www.samba.org/samba/docs/Samba3-HOWTO.pdf\n"));
  51         DEBUGSEP(0);
  52
  53         smb_panic("internal error");
  54
  55         if (cont_fn) {
  56                 cont_fn(NULL);
  57 #ifdef SIGSEGV
  58                 CatchSignal(SIGSEGV, SIG_DFL);
  59 #endif
  60 #ifdef SIGBUS
  61                 CatchSignal(SIGBUS, SIG_DFL);
  62 #endif
  63 #ifdef SIGABRT
  64                 CatchSignal(SIGABRT, SIG_DFL);
  65 #endif
  66                 return; /* this should cause a core dump */
  67         }
  68         exit(1);
  69 }
  70
  71 /****************************************************************************
  72 catch serious errors
  73 ****************************************************************************/
  74 static void sig_fault(int sig)
  75 {
  76         fault_report(sig);
  77 }
  78
  79 /*******************************************************************
  80 setup our fault handlers
  81 ********************************************************************/
  82 void fault_setup(void (*fn)(void *))
  83 {
  84         cont_fn = fn;
  85
  86 #ifdef SIGSEGV
  87         CatchSignal(SIGSEGV, sig_fault);
  88 #endif
  89 #ifdef SIGBUS
  90         CatchSignal(SIGBUS, sig_fault);
  91 #endif
  92 #ifdef SIGABRT
  93         CatchSignal(SIGABRT, sig_fault);
  94 #endif
  95 }
  96
  97 /**
  98  * Build up the default corepath as "<logbase>/cores/<progname>"
  99  */
 100 static char *get_default_corepath(const char *logbase, const char *progname)
 101 {
 102         char *tmp_corepath;
 103
 104         /* Setup core dir in logbase. */
 105         tmp_corepath = talloc_asprintf(NULL, "%s/cores", logbase);
 106         if (!tmp_corepath)
 107                 return NULL;
 108
 109         if ((mkdir(tmp_corepath, 0700) == -1) && errno != EEXIST)
 110                 goto err_out;
 111
 112         if (chmod(tmp_corepath, 0700) == -1)
 113                 goto err_out;
 114
 115         talloc_free(tmp_corepath);
 116
 117         /* Setup progname-specific core subdir */
 118         tmp_corepath = talloc_asprintf(NULL, "%s/cores/%s", logbase, progname);
 119         if (!tmp_corepath)
 120                 return NULL;
 121
 122         if (mkdir(tmp_corepath, 0700) == -1 && errno != EEXIST)
 123                 goto err_out;
 124
 125         if (chown(tmp_corepath, getuid(), getgid()) == -1)
 126                 goto err_out;
 127
 128         if (chmod(tmp_corepath, 0700) == -1)
 129                 goto err_out;
 130
 131         return tmp_corepath;
 132
 133  err_out:
 134         talloc_free(tmp_corepath);
 135         return NULL;
 136 }
 137
 138 /**
 139  * Get the FreeBSD corepath.
 140  *
 141  * On FreeBSD the current working directory is ignored when creating a core
 142  * file.  Instead the core directory is controlled via sysctl.  This consults
 143  * the value of "kern.corefile" so the correct corepath can be printed out
 144  * before dump_core() calls abort.
 145  */
 146 #if (defined(FREEBSD) && defined(HAVE_SYSCTLBYNAME))
 147 static char *get_freebsd_corepath(void)
 148 {
 149         char *tmp_corepath = NULL;
 150         char *end = NULL;
 151         size_t len = 128;
 152         int ret;
 153
 154         /* Loop with increasing sizes so we don't allocate too much. */
 155         do {
 156                 if (len > 1024)  {
 157                         goto err_out;
 158                 }
 159
 160                 tmp_corepath = (char *)talloc_realloc(NULL, tmp_corepath,
 161                                                       char, len);
 162                 if (!tmp_corepath) {
 163                         return NULL;
 164                 }
 165
 166                 ret = sysctlbyname("kern.corefile", tmp_corepath, &len, NULL,
 167                                    0);
 168                 if (ret == -1) {
 169                         if (errno != ENOMEM) {
 170                                 DEBUG(0, ("sysctlbyname failed getting "
 171                                           "kern.corefile %s\n",
 172                                           strerror(errno)));
 173                                 goto err_out;
 174                         }
 175
 176                         /* Not a large enough array, try a bigger one. */
 177                         len = len << 1;
 178                 }
 179         } while (ret == -1);
 180
 181         /* Strip off the common filename expansion */
 182         if ((end = strrchr_m(tmp_corepath, '/'))) {
 183                 *end = '\0';
 184         }
 185
 186         return tmp_corepath;
 187
 188  err_out:
 189         if (tmp_corepath) {
 190                 talloc_free(tmp_corepath);
 191         }
 192         return NULL;
 193 }
 194 #endif
 195
 196 #if defined(HAVE_SYS_KERNEL_PROC_CORE_PATTERN)
 197
 198 /**
 199  * Get the Linux corepath.
 200  *
 201  * On Linux the contents of /proc/sys/kernel/core_pattern indicates the
 202  * location of the core path.
 203  */
 204 static char *get_linux_corepath(void)
 205 {
 206         char *end;
 207         int fd;
 208         char *result;
 209
 210         fd = open("/proc/sys/kernel/core_pattern", O_RDONLY, 0);
 211         if (fd == -1) {
 212                 return NULL;
 213         }
 214
 215         result = afdgets(fd, NULL, 0);
 216         close(fd);
 217
 218         if (result == NULL) {
 219                 return NULL;
 220         }
 221
 222         if (result[0] != '/') {
 223                 /*
 224                  * No absolute path, use the default (cwd)
 225                  */
 226                 TALLOC_FREE(result);
 227                 return NULL;
 228         }
 229         /* Strip off the common filename expansion */
 230
 231         end = strrchr_m(result, '/');
 232
 233         if ((end != result) /* this would be the only / */
 234             && (end != NULL)) {
 235                 *end = '\0';
 236         }
 237         return result;
 238 }
 239 #endif
 240
 241
 242 /**
 243  * Try getting system-specific corepath if one exists.
 244  *
 245  * If the system doesn't define a corepath, then the default is used.
 246  */
 247 static char *get_corepath(const char *logbase, const char *progname)
 248 {
 249 #if (defined(FREEBSD) && defined(HAVE_SYSCTLBYNAME))
 250         char *tmp_corepath = NULL;
 251         tmp_corepath = get_freebsd_corepath();
 252
 253         /* If this has been set correctly, we're done. */
 254         if (tmp_corepath) {
 255                 return tmp_corepath;
 256         }
 257 #endif
 258
 259 #if defined(HAVE_SYS_KERNEL_PROC_CORE_PATTERN)
 260         char *tmp_corepath = NULL;
 261         tmp_corepath = get_linux_corepath();
 262
 263         /* If this has been set correctly, we're done. */
 264         if (tmp_corepath) {
 265                 return tmp_corepath;
 266         }
 267 #endif
 268
 269         /* Fall back to the default. */
 270         return get_default_corepath(logbase, progname);
 271 }
 272
 273 /*******************************************************************
 274 make all the preparations to safely dump a core file
 275 ********************************************************************/
 276
 277 void dump_core_setup(const char *progname)
 278 {
 279         char *logbase = NULL;
 280         char *end = NULL;
 281
 282         if (lp_logfile() && *lp_logfile()) {
 283                 if (asprintf(&logbase, "%s", lp_logfile()) < 0) {
 284                         return;
 285                 }
 286                 if ((end = strrchr_m(logbase, '/'))) {
 287                         *end = '\0';
 288                 }
 289         } else {
 290                 /* We will end up here if the log file is given on the command
 291                  * line by the -l option but the "log file" option is not set
 292                  * in smb.conf.
 293                  */
 294                 if (asprintf(&logbase, "%s", get_dyn_LOGFILEBASE()) < 0) {
 295                         return;
 296                 }
 297         }
 298
 299         SMB_ASSERT(progname != NULL);
 300
 301         corepath = get_corepath(logbase, progname);
 302         if (!corepath) {
 303                 DEBUG(0, ("Unable to setup corepath for %s: %s\n", progname,
 304                           strerror(errno)));
 305                 goto out;
 306         }
 307
 308
 309 #ifdef HAVE_GETRLIMIT
 310 #ifdef RLIMIT_CORE
 311         {
 312                 struct rlimit rlp;
 313                 getrlimit(RLIMIT_CORE, &rlp);
 314                 rlp.rlim_cur = MAX(16*1024*1024,rlp.rlim_cur);
 315                 setrlimit(RLIMIT_CORE, &rlp);
 316                 getrlimit(RLIMIT_CORE, &rlp);
 317                 DEBUG(3,("Maximum core file size limits now %d(soft) %d(hard)\n",
 318                          (int)rlp.rlim_cur,(int)rlp.rlim_max));
 319         }
 320 #endif
 321 #endif
 322
 323         /* FIXME: if we have a core-plus-pid facility, configurably set
 324          * this up here.
 325          */
 326  out:
 327         SAFE_FREE(logbase);
 328 }
 329
 330  void dump_core(void)
 331 {
 332         static bool called;
 333
 334         if (called) {
 335                 DEBUG(0, ("dump_core() called recursive\n"));
 336                 exit(1);
 337         }
 338         called = true;
 339
 340         /* Note that even if core dumping has been disabled, we still set up
 341          * the core path. This is to handle the case where core dumping is
 342          * turned on in smb.conf and the relevant daemon is not restarted.
 343          */
 344         if (!lp_enable_core_files()) {
 345                 DEBUG(0, ("Exiting on internal error (core file administratively disabled)\n"));
 346                 exit(1);
 347         }
 348
 349 #if DUMP_CORE
 350         /* If we're running as non root we might not be able to dump the core
 351          * file to the corepath.  There must not be an unbecome_root() before
 352          * we call abort(). */
 353         if (geteuid() != sec_initial_uid()) {
 354                 become_root();
 355         }
 356
 357         if (corepath == NULL) {
 358                 DEBUG(0, ("Can not dump core: corepath not set up\n"));
 359                 exit(1);
 360         }
 361
 362         if (*corepath != '\0') {
 363                 /* The chdir might fail if we dump core before we finish
 364                  * processing the config file.
 365                  */
 366                 if (chdir(corepath) != 0) {
 367                         DEBUG(0, ("unable to change to %s\n", corepath));
 368                         DEBUGADD(0, ("refusing to dump core\n"));
 369                         exit(1);
 370                 }
 371
 372                 DEBUG(0,("dumping core in %s\n", corepath));
 373         }
 374
 375         umask(~(0700));
 376         dbgflush();
 377
 378 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
 379         /* On Linux we lose the ability to dump core when we change our user
 380          * ID. We know how to dump core safely, so let's make sure we have our
 381          * dumpable flag set.
 382          */
 383         prctl(PR_SET_DUMPABLE, 1);
 384 #endif
 385
 386         /* Ensure we don't have a signal handler for abort. */
 387 #ifdef SIGABRT
 388         CatchSignal(SIGABRT, SIG_DFL);
 389 #endif
 390
 391         abort();
 392
 393 #else /* DUMP_CORE */
 394         exit(1);
 395 #endif /* DUMP_CORE */
 396 }
 397