/* CCpp.cpp - the hook for C/C++ crashing program Copyright (C) 2009 Zdenek Prikryl (zprikryl@redhat.com) Copyright (C) 2009 RedHat inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #include "abrtlib.h" #include "DebugDump.h" #include "ABRTException.h" #include #define FILENAME_EXECUTABLE "executable" #define FILENAME_COREDUMP "coredump" using namespace std; static char* malloc_readlink(const char *linkname) { char buf[PATH_MAX + 1]; int len; len = readlink(linkname, buf, sizeof(buf)-1); if (len >= 0) { buf[len] = '\0'; return xstrdup(buf); } return NULL; } static char* get_executable(pid_t pid) { char buf[sizeof("/proc/%u/exe") + sizeof(int)*3]; sprintf(buf, "/proc/%u/exe", (int)pid); return malloc_readlink(buf); } static char* get_cwd(pid_t pid) { char buf[sizeof("/proc/%u/cwd") + sizeof(int)*3]; sprintf(buf, "/proc/%u/cwd", (int)pid); return malloc_readlink(buf); } int main(int argc, char** argv) { int fd; struct stat sb; const char* program_name = argv[0]; if (argc < 5) { error_msg_and_die("Usage: %s: DUMPDIR PID SIGNO UID CORE_SIZE_LIMIT", program_name); } openlog("abrt", 0, LOG_DAEMON); logmode = LOGMODE_SYSLOG; errno = 0; const char* dddir = argv[1]; pid_t pid = xatoi_u(argv[2]); const char* signal_str = argv[3]; int signal_no = xatoi_u(argv[3]); uid_t uid = xatoi_u(argv[4]); off_t ulimit_c = strtoull(argv[5], NULL, 10); off_t core_size = 0; if (errno || pid <= 0 || ulimit_c < 0) { error_msg_and_die("pid '%s' or limit '%s' is bogus", argv[2], argv[5]); } if (signal_no != SIGQUIT && signal_no != SIGILL && signal_no != SIGABRT && signal_no != SIGFPE && signal_no != SIGSEGV ) { /* not an error, exit silently */ return 0; } char *user_pwd = get_cwd(pid); /* may be NULL on error */ int core_fd = STDIN_FILENO; if (!daemon_is_ok()) { /* not an error, exit with exitcode 0 */ log("abrt daemon is not running. If it crashed, " "/proc/sys/kernel/core_pattern contains a stale value, " "consider resetting it to 'core'" ); goto create_user_core; } try { char* executable = get_executable(pid); if (executable == NULL) { error_msg_and_die("can't read /proc/%u/exe link", (int)pid); } if (strstr(executable, "/abrt-hook-ccpp")) { error_msg_and_die("pid %u is '%s', not dumping it to avoid recursion", (int)pid, executable); } /* Parse abrt.conf and plugins/CCpp.conf */ unsigned setting_MaxCrashReportsSize = 0; bool setting_MakeCompatCore = false; bool abrt_conf = true; FILE *fp = fopen(CONF_DIR"/abrt.conf", "r"); if (fp) { char line[256]; while (1) { if (fgets(line, sizeof(line), fp) == NULL) { /* Next .conf file plz */ if (abrt_conf) { abrt_conf = false; fp = fopen(CONF_DIR"/plugins/CCpp.conf", "r"); if (fp) continue; } break; } unsigned len = strlen(line); if (len > 0 && line[len-1] == '\n') line[--len] = '\0'; const char *p = skip_whitespace(line); #undef DIRECTIVE #define DIRECTIVE "MaxCrashReportsSize" if (strncmp(p, DIRECTIVE, sizeof(DIRECTIVE)-1) == 0) { p = skip_whitespace(p + sizeof(DIRECTIVE)-1); if (*p != '=') continue; p = skip_whitespace(p + 1); if (isdigit(*p)) /* x1.25: go a bit up, so that usual in-daemon trimming * kicks in first, and we don't "fight" with it. */ setting_MaxCrashReportsSize = (unsigned long)xatou(p) * 5 / 4; continue; } #undef DIRECTIVE #define DIRECTIVE "MakeCompatCore" if (strncmp(p, DIRECTIVE, sizeof(DIRECTIVE)-1) == 0) { p = skip_whitespace(p + sizeof(DIRECTIVE)-1); if (*p != '=') continue; p = skip_whitespace(p + 1); setting_MakeCompatCore = string_to_bool(p); continue; } #undef DIRECTIVE /* add more 'if (strncmp(p, DIRECTIVE, sizeof(DIRECTIVE)-1) == 0)' here... */ } fclose(fp); } char path[PATH_MAX]; /* Check /var/cache/abrt/last-ccpp marker, do not dump repeated crashes * if they happen too often. Else, write new marker value. */ snprintf(path, sizeof(path), "%s/last-ccpp", dddir); fd = open(path, O_RDWR | O_CREAT, 0666); if (fd >= 0) { int sz; fstat(fd, &sb); /* !paranoia. this can't fail. */ if (sb.st_size != 0 /* if it wasn't created by us just now... */ && (unsigned)(time(NULL) - sb.st_mtime) < 20 /* and is relatively new [is 20 sec ok?] */ ) { sz = read(fd, path, sizeof(path)-1); /* (ab)using path as scratch buf */ if (sz > 0) { path[sz] = '\0'; if (strcmp(executable, path) == 0) { error_msg("not dumping repeating crash in '%s'", executable); if (setting_MakeCompatCore) goto create_user_core; return 1; } } lseek(fd, 0, SEEK_SET); } sz = write(fd, executable, strlen(executable)); if (sz >= 0) ftruncate(fd, sz); close(fd); } if (strstr(executable, "/abrtd")) { /* If abrtd crashes, we don't want to create a _directory_, * since that can make new copy of abrtd to process it, * and maybe crash again... * Unlike dirs, mere files are ignored by abrtd. */ snprintf(path, sizeof(path), "%s/abrtd-coredump", dddir); core_fd = xopen3(path, O_WRONLY | O_CREAT | O_TRUNC, 0644); core_size = copyfd_eof(STDIN_FILENO, core_fd); if (core_size < 0 || close(core_fd) != 0) { unlink(path); /* copyfd_eof logs the error including errno string, * but it does not log file name */ error_msg_and_die("error saving coredump to %s", path); } log("saved core dump of pid %u (%s) to %s (%llu bytes)", (int)pid, executable, path, (long long)core_size); return 0; } char* cmdline = get_cmdline(pid); /* never NULL */ const char *signame = strsignal(signal_no); char *reason = xasprintf("Process was terminated by signal %s (%s)", signal_str, signame ? signame : signal_str); snprintf(path, sizeof(path), "%s/ccpp-%ld-%u", dddir, (long)time(NULL), (int)pid); CDebugDump dd; dd.Create(path, uid); dd.SaveText(FILENAME_ANALYZER, "CCpp"); dd.SaveText(FILENAME_EXECUTABLE, executable); dd.SaveText(FILENAME_CMDLINE, cmdline); dd.SaveText(FILENAME_REASON, reason); int len = strlen(path); snprintf(path + len, sizeof(path) - len, "/"FILENAME_COREDUMP); /* We need coredumps to be readable by all, because * when abrt daemon processes coredump, * process producing backtrace is run under the same UID * as the crashed process. * Thus 644, not 600 */ core_fd = open(path, O_RDWR | O_CREAT | O_TRUNC, 0644); if (core_fd < 0) { dd.Delete(); dd.Close(); perror_msg_and_die("can't open '%s'", path); } core_size = copyfd_eof(STDIN_FILENO, core_fd); if (core_size < 0 || fsync(core_fd) != 0) { unlink(path); dd.Delete(); dd.Close(); /* copyfd_eof logs the error including errno string, * but it does not log file name */ error_msg_and_die("error saving coredump to %s", path); } lseek(core_fd, 0, SEEK_SET); /* note: core_fd is still open, we may use it later to copy core to user's dir */ log("saved core dump of pid %u (%s) to %s (%llu bytes)", (int)pid, executable, path, (long long)core_size); free(executable); free(cmdline); path[len] = '\0'; /* path now contains directory name */ /* We close dumpdir before we start catering for crash storm case. * Otherwise, delete_debug_dump_dir's from other concurrent * CCpp's won't be able to delete our dump (their delete_debug_dump_dir * will wait for us), and we won't be able to delete their dumps. * Classic deadlock. */ dd.Close(); /* rhbz#539551: "abrt going crazy when crashing process is respawned". * Do we want to protect against or ameliorate this? How? Ideas: * (1) nice ourself? * (2) check total size of dump dir, if it overflows, either abort dump * or delete oldest/biggest dumps? [abort would be simpler, * abrtd already does "delete on overflow" thing] * (3) detect parallel dumps in progress and back off * (pause/renice further/??) */ if (setting_MaxCrashReportsSize > 0) { string worst_dir; while (1) { const char *base_dirname = strrchr(path, '/') + 1; /* never NULL */ /* We exclude our own dump from candidates for deletion (3rd param): */ double dirsize = get_dirsize_find_largest_dir(DEBUG_DUMPS_DIR, &worst_dir, base_dirname); if (dirsize / (1024*1024) < setting_MaxCrashReportsSize || worst_dir == "") break; log("size of '%s' >= %u MB, deleting '%s'", DEBUG_DUMPS_DIR, setting_MaxCrashReportsSize, worst_dir.c_str()); delete_debug_dump_dir(concat_path_file(DEBUG_DUMPS_DIR, worst_dir.c_str()).c_str()); worst_dir = ""; } } if (!setting_MakeCompatCore) return 0; /* fall through to creating user core */ } catch (CABRTException& e) { error_msg_and_die("%s", e.what()); } catch (std::exception& e) { error_msg_and_die("%s", e.what()); } create_user_core: /* note: core_size may be == 0 ("unknown") */ if (core_size > ulimit_c || ulimit_c == 0) return 0; /* Write a core file for user */ struct passwd* pw = getpwuid(uid); gid_t gid = pw ? pw->pw_gid : uid; setgroups(1, &gid); xsetregid(gid, gid); xsetreuid(uid, uid); errno = 0; if (user_pwd == NULL || chdir(user_pwd) != 0 ) { perror_msg_and_die("can't cd to %s", user_pwd); } /* Mimic "core.PID" if requested */ char core_basename[sizeof("core.%u") + sizeof(int)*3] = "core"; char buf[] = "0\n"; fd = open("/proc/sys/kernel/core_uses_pid", O_RDONLY); if (fd >= 0) { read(fd, buf, sizeof(buf)); close(fd); } if (strcmp(buf, "1\n") == 0) { sprintf(core_basename, "core.%u", (int)pid); } /* man core: * There are various circumstances in which a core dump file * is not produced: * * [skipped obvious ones] * The process does not have permission to write the core file. * ...if a file with the same name exists and is not writable * or is not a regular file (e.g., it is a directory or a symbolic link). * * A file with the same name already exists, but there is more * than one hard link to that file. * * The file system where the core dump file would be created is full; * or has run out of inodes; or is mounted read-only; * or the user has reached their quota for the file system. * * The RLIMIT_CORE or RLIMIT_FSIZE resource limits for the process * are set to zero. * [shouldn't it be checked by kernel? 2.6.30.9-96 doesn't, still * calls us even if "ulimit -c 0"] * * The binary being executed by the process does not have * read permission enabled. [how we can check it here?] * * The process is executing a set-user-ID (set-group-ID) program * that is owned by a user (group) other than the real * user (group) ID of the process. [TODO?] * (However, see the description of the prctl(2) PR_SET_DUMPABLE operation, * and the description of the /proc/sys/fs/suid_dumpable file in proc(5).) */ /* Do not O_TRUNC: if later checks fail, we do not want to have file already modified here */ errno = 0; int usercore_fd = open(core_basename, O_WRONLY | O_CREAT | O_NOFOLLOW, 0600); /* kernel makes 0600 too */ if (usercore_fd < 0 || fstat(usercore_fd, &sb) != 0 || !S_ISREG(sb.st_mode) || sb.st_nlink != 1 /* kernel internal dumper checks this too: if (inode->i_uid != current->fsuid) , need to mimic? */ ) { perror_msg_and_die("%s/%s is not a regular file with link count 1", user_pwd, core_basename); } /* Note: we do not copy more than ulimit_c */ off_t size; if (ftruncate(usercore_fd, 0) != 0 || (size = copyfd_size(core_fd, usercore_fd, ulimit_c)) < 0 || close(usercore_fd) != 0 ) { /* perror first, otherwise unlink may trash errno */ perror_msg("write error writing %s/%s", user_pwd, core_basename); unlink(core_basename); return 1; } if (size == ulimit_c && size != core_size) { /* We copied exactly ulimit_c bytes (and it doesn't accidentally match * core_size (imagine exactly 1MB coredump with "ulimit -c 1M" - that'd be ok)), * it means that core is larger than ulimit_c. Abort and delete the dump. */ unlink(core_basename); return 1; } log("saved core dump of pid %u to %s/%s (%llu bytes)", (int)pid, user_pwd, core_basename, (long long)size); return 0; }