source3/lib/dumpcore.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Samba utility functions
   4
   5    Copyright (C) Andrew Tridgell 1992-2011
   6
   7    based on old fault.c code, which had:
   8
   9    Copyright (C) Jeremy Allison 2001-2007
  10    Copyright (C) Simo Sorce 2001
  11    Copyright (C) Jim McDonough <jmcd@us.ibm.com> 2003
  12    Copyright (C) James Peach 2006
  13
  14    This program is free software; you can redistribute it and/or modify
  15    it under the terms of the GNU General Public License as published by
  16    the Free Software Foundation; either version 3 of the License, or
  17    (at your option) any later version.
  18
  19    This program is distributed in the hope that it will be useful,
  20    but WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22    GNU General Public License for more details.
  23
  24    You should have received a copy of the GNU General Public License
  25    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  26 */
  27
  28 #include "includes.h"
  29 #include "system/filesys.h"
  30
  31 #ifdef HAVE_SYS_SYSCTL_H
  32 #include <sys/sysctl.h>
  33 #endif
  34
  35 #ifdef HAVE_SYS_PRCTL_H
  36 #include <sys/prctl.h>
  37 #endif
  38
  39 static char *corepath;
  40 static bool using_helper_binary = false;
  41
  42 /**
  43  * Build up the default corepath as "<logbase>/cores/<progname>"
  44  */
  45 static char *get_default_corepath(const char *logbase, const char *progname)
  46 {
  47         const mode_t mode = 0700;
  48         const uid_t uid = getuid();
  49         char *tmp_corepath;
  50
  51         /* Setup core dir in logbase. */
  52         tmp_corepath = talloc_asprintf(NULL, "%s/cores", logbase);
  53         if (!tmp_corepath) {
  54                 DEBUG(0, ("Out of memory\n"));
  55                 return NULL;
  56         }
  57
  58         if (!directory_create_or_exist_strict(tmp_corepath, uid, mode)) {
  59                 DEBUG(0, ("Failed to create %s for user %d with mode 0%o\n",
  60                           tmp_corepath, (int)uid, (int)mode));
  61                 goto err_out;
  62         }
  63
  64         /* Setup progname-specific core subdir */
  65         tmp_corepath = talloc_asprintf_append(tmp_corepath, "/%s", progname);
  66         if (!tmp_corepath) {
  67                 DEBUG(0, ("Out of memory\n"));
  68                 goto err_out;
  69         }
  70
  71         if (!directory_create_or_exist(tmp_corepath, mode)) {
  72                 DEBUG(0, ("Failed to create %s for user %d with mode 0%o\n",
  73                           tmp_corepath, (int)uid, (int)mode));
  74                 goto err_out;
  75         }
  76
  77         return tmp_corepath;
  78
  79  err_out:
  80         talloc_free(tmp_corepath);
  81         return NULL;
  82 }
  83
  84
  85 /**
  86  * Get the FreeBSD corepath.
  87  *
  88  * On FreeBSD the current working directory is ignored when creating a core
  89  * file.  Instead the core directory is controlled via sysctl.  This consults
  90  * the value of "kern.corefile" so the correct corepath can be printed out
  91  * before dump_core() calls abort.
  92  */
  93 #if (defined(FREEBSD) && defined(HAVE_SYSCTLBYNAME))
  94 static char *get_freebsd_corepath(void)
  95 {
  96         char *tmp_corepath = NULL;
  97         char *end = NULL;
  98         size_t len = 128;
  99         int ret;
 100
 101         /* Loop with increasing sizes so we don't allocate too much. */
 102         do {
 103                 if (len > 1024)  {
 104                         goto err_out;
 105                 }
 106
 107                 tmp_corepath = (char *)talloc_realloc(NULL, tmp_corepath,
 108                                                       char, len);
 109                 if (!tmp_corepath) {
 110                         return NULL;
 111                 }
 112
 113                 ret = sysctlbyname("kern.corefile", tmp_corepath, &len, NULL,
 114                                    0);
 115                 if (ret == -1) {
 116                         if (errno != ENOMEM) {
 117                                 DEBUG(0, ("sysctlbyname failed getting "
 118                                           "kern.corefile %s\n",
 119                                           strerror(errno)));
 120                                 goto err_out;
 121                         }
 122
 123                         /* Not a large enough array, try a bigger one. */
 124                         len = len << 1;
 125                 }
 126         } while (ret == -1);
 127
 128         /* Strip off the common filename expansion */
 129         if ((end = strrchr_m(tmp_corepath, '/'))) {
 130                 *end = '\0';
 131         }
 132
 133         return tmp_corepath;
 134
 135  err_out:
 136         if (tmp_corepath) {
 137                 talloc_free(tmp_corepath);
 138         }
 139         return NULL;
 140 }
 141 #endif
 142
 143 #if defined(HAVE_SYS_KERNEL_PROC_CORE_PATTERN)
 144
 145 /**
 146  * Get the Linux corepath.
 147  *
 148  * On Linux the contents of /proc/sys/kernel/core_pattern indicates the
 149  * location of the core path.
 150  */
 151 static char *get_linux_corepath(void)
 152 {
 153         char *end;
 154         int fd;
 155         char *result;
 156
 157         fd = open("/proc/sys/kernel/core_pattern", O_RDONLY, 0);
 158         if (fd == -1) {
 159                 return NULL;
 160         }
 161
 162         result = afdgets(fd, NULL, 0);
 163         close(fd);
 164
 165         if (result == NULL) {
 166                 return NULL;
 167         }
 168
 169         if (result[0] != '/') {
 170                 /*
 171                  * No absolute path, use the default (cwd)
 172                  */
 173                 if (result[0] == '|') {
 174                         /*
 175                         * Core dump handled by helper binaries
 176                         */
 177                         using_helper_binary = true;
 178                 }
 179                 TALLOC_FREE(result);
 180                 return NULL;
 181         }
 182         /* Strip off the common filename expansion */
 183
 184         end = strrchr_m(result, '/');
 185
 186         if ((end != result) /* this would be the only / */
 187             && (end != NULL)) {
 188                 *end = '\0';
 189         }
 190         return result;
 191 }
 192 #endif
 193
 194
 195 /**
 196  * Try getting system-specific corepath if one exists.
 197  *
 198  * If the system doesn't define a corepath, then the default is used.
 199  */
 200 static char *get_corepath(const char *logbase, const char *progname)
 201 {
 202 #if (defined(FREEBSD) && defined(HAVE_SYSCTLBYNAME))
 203         char *tmp_corepath = NULL;
 204         tmp_corepath = get_freebsd_corepath();
 205
 206         /* If this has been set correctly, we're done. */
 207         if (tmp_corepath) {
 208                 return tmp_corepath;
 209         }
 210 #endif
 211
 212 #if defined(HAVE_SYS_KERNEL_PROC_CORE_PATTERN)
 213         char *tmp_corepath = NULL;
 214         tmp_corepath = get_linux_corepath();
 215
 216         /* If this has been set correctly, we're done. */
 217         if (tmp_corepath) {
 218                 return tmp_corepath;
 219         }
 220 #endif
 221
 222         /* Fall back to the default. */
 223         return get_default_corepath(logbase, progname);
 224 }
 225
 226 /*******************************************************************
 227 make all the preparations to safely dump a core file
 228 ********************************************************************/
 229
 230 void dump_core_setup(const char *progname, const char *log_file)
 231 {
 232         char *logbase = NULL;
 233         char *end = NULL;
 234
 235         if (log_file && *log_file) {
 236                 if (asprintf(&logbase, "%s", log_file) < 0) {
 237                         return;
 238                 }
 239                 if ((end = strrchr_m(logbase, '/'))) {
 240                         *end = '\0';
 241                 }
 242         } else {
 243                 /* We will end up here if the log file is given on the command
 244                  * line by the -l option but the "log file" option is not set
 245                  * in smb.conf.
 246                  */
 247                 if (asprintf(&logbase, "%s", get_dyn_LOGFILEBASE()) < 0) {
 248                         return;
 249                 }
 250         }
 251
 252         SMB_ASSERT(progname != NULL);
 253
 254         corepath = get_corepath(logbase, progname);
 255         if (!corepath) {
 256                 DEBUG(0, ("Unable to setup corepath for %s: %s\n", progname,
 257                           strerror(errno)));
 258                 goto out;
 259         }
 260
 261         /* FIXME: if we have a core-plus-pid facility, configurably set
 262          * this up here.
 263          */
 264  out:
 265         SAFE_FREE(logbase);
 266 }
 267
 268  void dump_core(void)
 269 {
 270         static bool called;
 271
 272         if (called) {
 273                 DEBUG(0, ("dump_core() called recursive\n"));
 274                 exit(1);
 275         }
 276         called = true;
 277
 278         /* Note that even if core dumping has been disabled, we still set up
 279          * the core path. This is to handle the case where core dumping is
 280          * turned on in smb.conf and the relevant daemon is not restarted.
 281          */
 282         if (!lp_enable_core_files()) {
 283                 DEBUG(0, ("Exiting on internal error (core file administratively disabled)\n"));
 284                 exit(1);
 285         }
 286
 287 #if DUMP_CORE
 288         /* If we're running as non root we might not be able to dump the core
 289          * file to the corepath.  There must not be an unbecome_root() before
 290          * we call abort(). */
 291         if (geteuid() != sec_initial_uid()) {
 292                 become_root();
 293         }
 294
 295         if (corepath == NULL) {
 296                 DEBUG(0, ("Can not dump core: corepath not set up\n"));
 297                 exit(1);
 298         }
 299
 300         if (*corepath != '\0') {
 301                 /*
 302                  * Check whether coredump is handled by helper binaries or not.
 303                  * If so skip chdir().
 304                  */
 305                 if (!using_helper_binary) {
 306                         /* The chdir might fail if we dump core before we finish
 307                          * processing the config file.
 308                          */
 309                         if (chdir(corepath) != 0) {
 310                                 DEBUG(0, ("unable to change to %s\n", corepath));
 311                                 DEBUGADD(0, ("refusing to dump core\n"));
 312                                 exit(1);
 313                         }
 314
 315                         DEBUG(0,("dumping core in %s\n", corepath));
 316                 } else {
 317                         DEBUG(0,("coredump is handled by helper binary "
 318                                  "specified at /proc/sys/kernel/core_pattern"));
 319                 }
 320         }
 321
 322         umask(~(0700));
 323         dbgflush();
 324
 325 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
 326         /* On Linux we lose the ability to dump core when we change our user
 327          * ID. We know how to dump core safely, so let's make sure we have our
 328          * dumpable flag set.
 329          */
 330         prctl(PR_SET_DUMPABLE, 1);
 331 #endif
 332
 333         /* Ensure we don't have a signal handler for abort. */
 334 #ifdef SIGABRT
 335         CatchSignal(SIGABRT, SIG_DFL);
 336 #endif
 337
 338         abort();
 339
 340 #else /* DUMP_CORE */
 341         exit(1);
 342 #endif /* DUMP_CORE */
 343 }