/* abrt-hook-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 "hooklib.h" #include "debug_dump.h" #include "crash_types.h" #include "abrt_exception.h" #include 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; } /* Custom version of copyfd_xyz, * one which is able to write into two descriptors at once. */ #define CONFIG_FEATURE_COPYBUF_KB 4 static off_t copyfd_sparse(int src_fd, int dst_fd1, int dst_fd2, off_t size2) { off_t total = 0; int last_was_seek = 0; #if CONFIG_FEATURE_COPYBUF_KB <= 4 char buffer[CONFIG_FEATURE_COPYBUF_KB * 1024]; enum { buffer_size = sizeof(buffer) }; #else char *buffer; int buffer_size; /* We want page-aligned buffer, just in case kernel is clever * and can do page-aligned io more efficiently */ buffer = mmap(NULL, CONFIG_FEATURE_COPYBUF_KB * 1024, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, /* ignored: */ -1, 0); buffer_size = CONFIG_FEATURE_COPYBUF_KB * 1024; if (buffer == MAP_FAILED) { buffer = alloca(4 * 1024); buffer_size = 4 * 1024; } #endif while (1) { ssize_t rd = safe_read(src_fd, buffer, buffer_size); if (!rd) { /* eof */ if (last_was_seek) { if (lseek(dst_fd1, -1, SEEK_CUR) < 0 || safe_write(dst_fd1, "", 1) != 1 || (dst_fd2 >= 0 && (lseek(dst_fd2, -1, SEEK_CUR) < 0 || safe_write(dst_fd2, "", 1) != 1 ) ) ) { perror_msg("write error"); total = -1; goto out; } } /* all done */ goto out; } if (rd < 0) { perror_msg("read error"); total = -1; goto out; } /* checking sparseness */ ssize_t cnt = rd; while (--cnt >= 0) { if (buffer[cnt] != 0) { /* not sparse */ errno = 0; ssize_t wr1 = full_write(dst_fd1, buffer, rd); ssize_t wr2 = (dst_fd2 >= 0 ? full_write(dst_fd2, buffer, rd) : rd); if (wr1 < rd || wr2 < rd) { perror_msg("write error"); total = -1; goto out; } last_was_seek = 0; goto adv; } } /* sparse */ xlseek(dst_fd1, rd, SEEK_CUR); if (dst_fd2 >= 0) xlseek(dst_fd2, rd, SEEK_CUR); last_was_seek = 1; adv: total += rd; size2 -= rd; if (size2 < 0) dst_fd2 = -1; } out: #if CONFIG_FEATURE_COPYBUF_KB > 4 if (buffer_size != 4 * 1024) munmap(buffer, buffer_size); #endif return total; } static char* get_executable(pid_t pid, int *fd_p) { char buf[sizeof("/proc/%lu/exe") + sizeof(long)*3]; sprintf(buf, "/proc/%lu/exe", (long)pid); *fd_p = open(buf, O_RDONLY); /* might fail and return -1, it's ok */ char *executable = malloc_readlink(buf); /* find and cut off " (deleted)" from the path */ char *deleted = executable + strlen(executable) - strlen(" (deleted)"); if (deleted > executable && strcmp(deleted, " (deleted)") == 0) { *deleted = '\0'; log("file %s seems to be deleted", executable); } /* find and cut off prelink suffixes from the path */ char *prelink = executable + strlen(executable) - strlen(".#prelink#.XXXXXX"); if (prelink > executable && strncmp(prelink, ".#prelink#.", strlen(".#prelink#.")) == 0) { log("file %s seems to be a prelink temporary file", executable); *prelink = '\0'; } return executable; } static char* get_cwd(pid_t pid) { char buf[sizeof("/proc/%lu/cwd") + sizeof(long)*3]; sprintf(buf, "/proc/%lu/cwd", (long)pid); return malloc_readlink(buf); } static char core_basename[sizeof("core.%lu") + sizeof(long)*3] = "core"; static int open_user_core(const char *user_pwd, uid_t uid, pid_t pid) { struct passwd* pw = getpwuid(uid); gid_t gid = pw ? pw->pw_gid : uid; xsetegid(gid); xseteuid(uid); errno = 0; if (user_pwd == NULL || chdir(user_pwd) != 0 ) { perror_msg("can't cd to %s", user_pwd); return 0; } /* Mimic "core.PID" if requested */ char buf[] = "0\n"; int 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.%lu", (long)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 */ struct stat sb; errno = 0; int user_core_fd = open(core_basename, O_WRONLY | O_CREAT | O_NOFOLLOW, 0600); /* kernel makes 0600 too */ xsetegid(0); xseteuid(0); if (user_core_fd < 0 || fstat(user_core_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("%s/%s is not a regular file with link count 1", user_pwd, core_basename); return -1; } if (ftruncate(user_core_fd, 0) != 0) { /* perror first, otherwise unlink may trash errno */ perror_msg("truncate %s/%s", user_pwd, core_basename); return -1; } return user_core_fd; } int main(int argc, char** argv) { int i; struct stat sb; if (argc < 5) { error_msg_and_die("Usage: %s: DUMPDIR PID SIGNO UID CORE_SIZE_LIMIT", argv[0]); } /* Not needed on 2.6.30. * At least 2.6.18 has a bug where * argv[1] = "DUMPDIR PID SIGNO UID CORE_SIZE_LIMIT" * argv[2] = "PID SIGNO UID CORE_SIZE_LIMIT" * and so on. Fixing it: */ for (i = 1; argv[i]; i++) { strchrnul(argv[i], ' ')[0] = '\0'; } openlog("abrt", LOG_PID, 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); if (ulimit_c < 0) /* unlimited? */ { /* set to max possible >0 value */ ulimit_c = ~((off_t)1 << (sizeof(off_t)*8-1)); } if (errno || pid <= 0) { error_msg_and_die("pid '%s' or limit '%s' is bogus", argv[2], argv[5]); } int src_fd_binary; char* executable = get_executable(pid, &src_fd_binary); if (executable == NULL) { perror_msg_and_die("can't read /proc/%lu/exe link", (long)pid); } if (strstr(executable, "/abrt-hook-ccpp")) { error_msg_and_die("pid %lu is '%s', not dumping it to avoid recursion", (long)pid, executable); } char *user_pwd = get_cwd(pid); /* may be NULL on error */ /* Parse abrt.conf and plugins/CCpp.conf */ unsigned setting_MaxCrashReportsSize = 0; bool setting_MakeCompatCore = false; bool setting_SaveBinaryImage = false; parse_conf(CONF_DIR"/plugins/CCpp.conf", &setting_MaxCrashReportsSize, &setting_MakeCompatCore, &setting_SaveBinaryImage); if (!setting_SaveBinaryImage && src_fd_binary >= 0) { close(src_fd_binary); src_fd_binary = -1; } /* Open a fd to compat coredump, if requested and is possible */ int user_core_fd = -1; if (setting_MakeCompatCore && ulimit_c != 0) user_core_fd = open_user_core(user_pwd, uid, pid); const char *signame = NULL; /* Tried to use array for this but C++ does not support v[] = { [IDX] = "str" } */ switch (signal_no) { case SIGILL : signame = "ILL" ; break; case SIGFPE : signame = "FPE" ; break; case SIGSEGV: signame = "SEGV"; break; case SIGBUS : signame = "BUS" ; break; //Bus error (bad memory access) case SIGABRT: signame = "ABRT"; break; //usually when abort() was called //case SIGQUIT: signame = "QUIT"; break; //Quit from keyboard //case SIGSYS : signame = "SYS" ; break; //Bad argument to routine (SVr4) //case SIGTRAP: signame = "TRAP"; break; //Trace/breakpoint trap //case SIGXCPU: signame = "XCPU"; break; //CPU time limit exceeded (4.2BSD) //case SIGXFSZ: signame = "XFSZ"; break; //File size limit exceeded (4.2BSD) default: goto create_user_core; // not a signal we care about } 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 { if (setting_MaxCrashReportsSize > 0) { check_free_space(setting_MaxCrashReportsSize); } char path[PATH_MAX]; /* Check /var/spool/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); int fd = open(path, O_RDWR | O_CREAT, 0600); 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); int abrt_core_fd = xopen3(path, O_WRONLY | O_CREAT | O_TRUNC, 0644); off_t core_size = copyfd_eof(STDIN_FILENO, abrt_core_fd, COPYFD_SPARSE); if (core_size < 0 || fsync(abrt_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 %lu (%s) to %s (%llu bytes)", (long)pid, executable, path, (long long)core_size); return 0; } unsigned path_len = snprintf(path, sizeof(path), "%s/ccpp-%ld-%lu.new", dddir, (long)time(NULL), (long)pid); if (path_len >= (sizeof(path) - sizeof("/"FILENAME_COREDUMP))) return 1; CDebugDump dd; if (dd.Create(path, uid)) { char *cmdline = get_cmdline(pid); /* never NULL */ char *reason = xasprintf("Process %s was killed by signal %s (SIG%s)", executable, signal_str, signame ? signame : signal_str); dd.SaveText(FILENAME_ANALYZER, "CCpp"); dd.SaveText(FILENAME_EXECUTABLE, executable); dd.SaveText(FILENAME_CMDLINE, cmdline); dd.SaveText(FILENAME_REASON, reason); free(cmdline); free(reason); if (src_fd_binary > 0) { strcpy(path + path_len, "/"FILENAME_BINARY); int dst_fd_binary = xopen3(path, O_WRONLY | O_CREAT | O_TRUNC, 0600); off_t sz = copyfd_eof(src_fd_binary, dst_fd_binary, COPYFD_SPARSE); if (sz < 0 || fsync(dst_fd_binary) != 0) { unlink(path); error_msg_and_die("error saving binary image to %s", path); } close(dst_fd_binary); close(src_fd_binary); } /* 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 */ strcpy(path + path_len, "/"FILENAME_COREDUMP); int abrt_core_fd = open(path, O_RDWR | O_CREAT | O_TRUNC, 0644); if (abrt_core_fd < 0) { int sv_errno = errno; dd.Delete(); dd.Close(); if (user_core_fd >= 0) { xchdir(user_pwd); unlink(core_basename); } errno = sv_errno; perror_msg_and_die("can't open '%s'", path); } /* We write both coredumps at once. * We can't write user coredump first, since it might be truncated * and thus can't be copied and used as abrt coredump; * and if we write abrt coredump first and then copy it as user one, * then we have a race when process exits but coredump does not exist yet: * $ echo -e '#include\nmain(){raise(SIGSEGV);}' | gcc -o test -x c - * $ rm -f core*; ulimit -c unlimited; ./test; ls -l core* * 21631 Segmentation fault (core dumped) ./test * ls: cannot access core*: No such file or directory <=== BAD */ //TODO: fchown abrt_core_fd to uid:abrt? //Currently it is owned by 0:0 but is readable by anyone, so the owner //of the crashed binary still can access it, as he has //r-x access to the dump dir. off_t core_size = copyfd_sparse(STDIN_FILENO, abrt_core_fd, user_core_fd, ulimit_c); if (core_size < 0 || fsync(abrt_core_fd) != 0) { unlink(path); dd.Delete(); dd.Close(); if (user_core_fd >= 0) { xchdir(user_pwd); unlink(core_basename); } /* copyfd_sparse logs the error including errno string, * but it does not log file name */ error_msg_and_die("error writing %s", path); } log("saved core dump of pid %lu (%s) to %s (%llu bytes)", (long)pid, executable, path, (long long)core_size); if (user_core_fd >= 0 && core_size >= ulimit_c) { /* user coredump is too big, nuke it */ xchdir(user_pwd); unlink(core_basename); } /* 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(); path[path_len] = '\0'; /* path now contains only directory name */ char *newpath = xstrndup(path, path_len - (sizeof(".new")-1)); if (rename(path, newpath) == 0) strcpy(path, newpath); free(newpath); /* rhbz#539551: "abrt going crazy when crashing process is respawned" */ if (setting_MaxCrashReportsSize > 0) { trim_debug_dumps(setting_MaxCrashReportsSize, path); } return 0; } else xfunc_die(); } catch (std::exception& e) { error_msg_and_die("%s", e.what()); } /* We didn't create abrt dump, but may need to create compat coredump */ create_user_core: if (user_core_fd < 0) return 0; off_t core_size = copyfd_size(STDIN_FILENO, user_core_fd, ulimit_c, COPYFD_SPARSE); if (core_size < 0 || fsync(user_core_fd) != 0) { /* perror first, otherwise unlink may trash errno */ perror_msg("error writing %s/%s", user_pwd, core_basename); xchdir(user_pwd); unlink(core_basename); return 1; } if (core_size >= ulimit_c) { xchdir(user_pwd); unlink(core_basename); return 1; } log("saved core dump of pid %lu to %s/%s (%llu bytes)", (long)pid, user_pwd, core_basename, (long long)core_size); return 0; }