diff options
Diffstat (limited to 'syslogd.c')
| -rw-r--r-- | syslogd.c | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/syslogd.c b/syslogd.c new file mode 100644 index 0000000..98c7aba --- /dev/null +++ b/syslogd.c @@ -0,0 +1,282 @@ +/* SPDX-License-Identifier: GPL-3.0-or-later */ +/* + * Copyright (C) 2018 - David Oberhollenzer + * + * 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 3 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, see <https://www.gnu.org/licenses/>. + */ +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/socket.h> +#include <unistd.h> +#include <stdlib.h> +#include <signal.h> +#include <string.h> +#include <getopt.h> +#include <errno.h> +#include <stdio.h> +#include <fcntl.h> +#include <pwd.h> +#include <grp.h> + +#include "syslogd.h" + +static const struct option long_opts[] = { + { "help", no_argument, NULL, 'h' }, + { "version", no_argument, NULL, 'V' }, + { "rotate-replace", no_argument, NULL, 'r' }, + { "chroot", no_argument, NULL, 'c' }, + { "max-size", required_argument, NULL, 'm' }, + { "user", required_argument, NULL, 'u' }, + { "group", required_argument, NULL, 'g' }, + { NULL, 0, NULL, 0 }, +}; + +static const char *short_opts = "hVcrm:u:g:"; + +const char *usage_string = +"Usage: usyslogd [OPTIONS..]\n\n" +"The following options are supported:\n" +" -h, --help Print this help text and exit\n" +" -V, --version Print version information and exit\n" +" -r, --rotate-replace Replace old log files when doing log rotation.\n" +" -m, --max-size <size> Automatically rotate log files bigger than this.\n" +" -u, --user <name> Run the syslog daemon as this user. If not set,\n" +" try to use the user '" DEFAULT_USER "'.\n" +" -g, --group <name> Run the syslog daemon as this group. If not set,\n" +" try to use the group '" DEFAULT_GROUP "'.\n" +" -c, --chroot If set, do a chroot into the log file path.\n"; + + + +static volatile sig_atomic_t syslog_run = 1; +static volatile sig_atomic_t syslog_rotate = 0; +static int log_flags = 0; +static size_t max_size = 0; +static uid_t uid = 0; +static gid_t gid = 0; +static bool dochroot = false; + + + +static void sighandler(int signo) +{ + switch (signo) { + case SIGINT: + case SIGTERM: + syslog_run = 0; + break; + case SIGHUP: + syslog_rotate = 1; + break; + default: + break; + } +} + +static void signal_setup(void) +{ + struct sigaction act; + + memset(&act, 0, sizeof(act)); + act.sa_handler = sighandler; + + sigaction(SIGINT, &act, NULL); + sigaction(SIGTERM, &act, NULL); + sigaction(SIGHUP, &act, NULL); +} + +static int handle_data(int fd) +{ + char buffer[2048]; + syslog_msg_t msg; + ssize_t ret; + + memset(buffer, 0, sizeof(buffer)); + + ret = read(fd, buffer, sizeof(buffer)); + if (ret <= 0) + return -1; + + if (syslog_msg_parse(&msg, buffer)) + return -1; + + return logmgr->write(logmgr, &msg); +} + +#define GPL_URL "https://gnu.org/licenses/gpl.html" + +static const char *version_string = +"usyslogd (usyslog) " PACKAGE_VERSION "\n" +"Copyright (C) 2018 David Oberhollenzer\n\n" +"License GPLv3+: GNU GPL version 3 or later <" GPL_URL ">.\n" +"This is free software: you are free to change and redistribute it.\n" +"There is NO WARRANTY, to the extent permitted by law.\n"; + +static void process_options(int argc, char **argv) +{ + struct passwd *pw = getpwnam(DEFAULT_USER); + struct group *grp = getgrnam(DEFAULT_GROUP); + char *end; + int i; + + if (pw != NULL) + uid = pw->pw_uid; + + if (grp != NULL) + gid = grp->gr_gid; + + for (;;) { + i = getopt_long(argc, argv, short_opts, long_opts, NULL); + if (i == -1) + break; + + switch (i) { + case 'r': + log_flags |= LOG_ROTATE_OVERWRITE; + break; + case 'm': + log_flags |= LOG_ROTATE_SIZE_LIMIT; + max_size = strtol(optarg, &end, 10); + if (max_size == 0 || *end != '\0') { + fputs("Numeric argument > 0 expected for -m\n", + stderr); + goto fail; + } + break; + case 'u': + pw = getpwnam(optarg); + if (pw == NULL) { + fprintf(stderr, "Cannot get UID for user %s\n", + optarg); + goto fail; + } + uid = pw->pw_uid; + break; + case 'g': + grp = getgrnam(optarg); + if (grp == NULL) { + fprintf(stderr, + "Cannot get GID for group %s\n", + optarg); + goto fail; + } + gid = grp->gr_gid; + break; + case 'c': + dochroot = true; + break; + case 'h': + fputs(usage_string, stdout); + exit(EXIT_SUCCESS); + case 'V': + fputs(version_string, stdout); + exit(EXIT_SUCCESS); + default: + goto fail; + } + } + return; +fail: + fputs("Try `usyslogd --help' for more information\n", stderr); + exit(EXIT_FAILURE); +} + +static int chroot_setup(void) +{ + if (mkdir(SYSLOG_PATH, 0750)) { + if (errno != EEXIST) { + perror("mkdir " SYSLOG_PATH); + return -1; + } + } + + if (uid > 0 && gid > 0 && chown(SYSLOG_PATH, uid, gid) != 0) { + perror("chown " SYSLOG_PATH); + return -1; + } + + if (chmod(SYSLOG_PATH, 0750)) { + perror("chmod " SYSLOG_PATH); + return -1; + } + + if (chdir(SYSLOG_PATH)) { + perror("cd " SYSLOG_PATH); + return -1; + } + + if (dochroot && chroot(SYSLOG_PATH) != 0) { + perror("chroot " SYSLOG_PATH); + return -1; + } + + return 0; +} + +static int user_setup(void) +{ + if (gid > 0 && setresgid(gid, gid, gid) != 0) { + perror("setgid"); + return -1; + } + if (uid > 0 && setresuid(uid, uid, uid) != 0) { + perror("setuid"); + return -1; + } + return 0; +} + +int main(int argc, char **argv) +{ + int sfd, status = EXIT_FAILURE; + + process_options(argc, argv); + + signal_setup(); + + sfd = mksock(SYSLOG_SOCKET); + if (sfd < 0) + return EXIT_FAILURE; + + if (uid > 0 && gid > 0 && chown(SYSLOG_SOCKET, uid, gid) != 0) { + perror("chown " SYSLOG_SOCKET); + return -1; + } + + if (chroot_setup()) + return EXIT_FAILURE; + + if (user_setup()) + return EXIT_FAILURE; + + if (logmgr->init(logmgr, log_flags, max_size)) + goto out; + + while (syslog_run) { + if (syslog_rotate) { + logmgr->rotate(logmgr); + syslog_rotate = 0; + } + + handle_data(sfd); + } + + status = EXIT_SUCCESS; +out: + logmgr->cleanup(logmgr); + if (sfd > 0) + close(sfd); + unlink(SYSLOG_SOCKET); + return status; +} |