diff options
Diffstat (limited to 'klogd.c')
| -rw-r--r-- | klogd.c | 193 |
1 files changed, 193 insertions, 0 deletions
@@ -0,0 +1,193 @@ +/* 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/klog.h> +#include <syslog.h> +#include <signal.h> +#include <string.h> +#include <stdlib.h> +#include <getopt.h> +#include <stdio.h> +#include <errno.h> + +#include "config.h" + +enum { + KLOG_CLOSE = 0, + KLOG_OPEN = 1, + KLOG_READ = 2, + KLOG_CONSOLE_OFF = 6, + KLOG_CONSOLE_ON = 7, + KLOG_CONSOLE_LEVEL = 8, +}; + +static char log_buffer[4096]; +static sig_atomic_t running = 1; +static int level = 0; + +static const struct option options[] = { + { "help", no_argument, NULL, 'h' }, + { "version", no_argument, NULL, 'V' }, + { "level", required_argument, NULL, 'l' }, + { NULL, 0, NULL, 0 }, +}; + +static const char *shortopt = "hVl:"; + +static const char *helptext = +"Usage: klogd [OPTION]... \n\n" +"Collect printk() messages from the kernel and forward them to syslogd.\n" +"\n" +"The following OPTIONSs can be used:\n" +" -l, --level <level> Minimum log level that should be printed to console.\n" +" If not set, logging to console is turned off.\n" +" -h, --help Print this help text and exit\n" +" -V, --version Print version information and exit\n\n"; + +#define GPL_URL "https://gnu.org/licenses/gpl.html" + +static const char *version_string = +"klogd (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) +{ + int c; + + for (;;) { + c = getopt_long(argc, argv, shortopt, options, NULL); + if (c == -1) + break; + + switch (c) { + case 'l': + level = strtoul(optarg, NULL, 10); + break; + case 'h': + fputs(helptext, stdout); + exit(EXIT_SUCCESS); + case 'V': + fputs(version_string, stdout); + exit(EXIT_SUCCESS); + default: + fputs("Try `klogd --help' for more information\n", + stderr); + exit(EXIT_FAILURE); + } + } +} + +static void sighandler(int signo) +{ + if (signo == SIGTERM || signo == SIGINT) + running = 0; +} + +static void sigsetup(void) +{ + struct sigaction act; + sigset_t mask; + + memset(&act, 0, sizeof(act)); + act.sa_handler = sighandler; + sigaction(SIGTERM, &act, NULL); + sigaction(SIGINT, &act, NULL); + + sigfillset(&mask); + sigdelset(&mask, SIGTERM); + sigdelset(&mask, SIGINT); + sigprocmask(SIG_SETMASK, &mask, NULL); +} + +static void log_open(void) +{ + klogctl(KLOG_OPEN, NULL, 0); + + if (level) { + klogctl(KLOG_CONSOLE_LEVEL, NULL, level); + } else { + klogctl(KLOG_CONSOLE_OFF, NULL, 0); + } + + openlog("kernel", 0, LOG_KERN); +} + +static void log_close(void) +{ + klogctl(KLOG_CONSOLE_ON, NULL, 0); + klogctl(KLOG_CLOSE, NULL, 0); + syslog(LOG_NOTICE, "-- klogd terminating --"); +} + +int main(int argc, char **argv) +{ + int diff, count = 0, priority, ret = EXIT_SUCCESS; + char *ptr, *end; + + process_options(argc, argv); + sigsetup(); + log_open(); + + /* TODO: seccomp lockdown? */ + + while (running) { + diff = klogctl(KLOG_READ, log_buffer + count, + sizeof(log_buffer) - 1 - count); + + if (diff < 0) { + if (errno == EINTR) + continue; + syslog(LOG_CRIT, "klogctl read: %s", strerror(errno)); + ret = EXIT_FAILURE; + break; + } + + count += diff; + log_buffer[count] = '\0'; + ptr = log_buffer; + + for (;;) { + end = strchr(ptr, '\n'); + if (end == NULL) { + count = strlen(ptr); + memmove(log_buffer, ptr, count); + break; + } + + *(end++) = '\0'; + priority = LOG_INFO; + + if (*ptr == '<') { + ++ptr; + if (*ptr) + priority = strtoul(ptr, &ptr, 10); + if (*ptr == '>') + ++ptr; + } + + if (*ptr) + syslog(priority, "%s", ptr); + ptr = end; + } + } + + log_close(); + return ret; +} |