X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=sysklogd%2Fklogd.c;h=25ddf3172f285ffdae2675b8ae2d8cfb1a92a78c;hb=6608879d34f9635572415e864b4fcbc497c74bcf;hp=677c9e6075bbe2011d74e31f59f7426ee526ae5b;hpb=d921b2ecc0d294ad4bf8c7458fc52a60c28727d2;p=oweals%2Fbusybox.git diff --git a/sysklogd/klogd.c b/sysklogd/klogd.c index 677c9e607..25ddf3172 100644 --- a/sysklogd/klogd.c +++ b/sysklogd/klogd.c @@ -4,7 +4,7 @@ * * Copyright (C) 2001 by Gennady Feldman . * Changes: Made this a standalone busybox module which uses standalone - * syslog() client interface. + * syslog() client interface. * * Copyright (C) 1999-2004 by Erik Andersen * @@ -14,111 +14,289 @@ * * Maintainer: Gennady Feldman as of Mar 12, 2001 * - * Licensed under the GPL v2 or later, see the file LICENSE in this tarball. + * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ +//config:config KLOGD +//config: bool "klogd (5.5 kb)" +//config: default y +//config: help +//config: klogd is a utility which intercepts and logs all +//config: messages from the Linux kernel and sends the messages +//config: out to the 'syslogd' utility so they can be logged. If +//config: you wish to record the messages produced by the kernel, +//config: you should enable this option. +//config: +//config:comment "klogd should not be used together with syslog to kernel printk buffer" +//config: depends on KLOGD && FEATURE_KMSG_SYSLOG +//config: +//config:config FEATURE_KLOGD_KLOGCTL +//config: bool "Use the klogctl() interface" +//config: default y +//config: depends on KLOGD +//config: select PLATFORM_LINUX +//config: help +//config: The klogd applet supports two interfaces for reading +//config: kernel messages. Linux provides the klogctl() interface +//config: which allows reading messages from the kernel ring buffer +//config: independently from the file system. +//config: +//config: If you answer 'N' here, klogd will use the more portable +//config: approach of reading them from /proc or a device node. +//config: However, this method requires the file to be available. +//config: +//config: If in doubt, say 'Y'. -#include "busybox.h" -#include -#include +//applet:IF_KLOGD(APPLET(klogd, BB_DIR_SBIN, BB_SUID_DROP)) -static void klogd_signal(int sig ATTRIBUTE_UNUSED) +//kbuild:lib-$(CONFIG_KLOGD) += klogd.o + +//usage:#define klogd_trivial_usage +//usage: "[-c N] [-n]" +//usage:#define klogd_full_usage "\n\n" +//usage: "Log kernel messages to syslog\n" +//usage: "\n -c N Print to console messages more urgent than prio N (1-8)" +//usage: "\n -n Run in foreground" + +#include "libbb.h" +#include "common_bufsiz.h" +#include + + +/* The Linux-specific klogctl(3) interface does not rely on the filesystem and + * allows us to change the console loglevel. Alternatively, we read the + * messages from _PATH_KLOG. */ + +#if ENABLE_FEATURE_KLOGD_KLOGCTL + +# include + +static void klogd_open(void) { - klogctl(7, NULL, 0); - klogctl(0, 0, 0); - /* logMessage(0, "Kernel log daemon exiting."); */ - syslog(LOG_NOTICE, "Kernel log daemon exiting."); - exit(EXIT_SUCCESS); + /* "Open the log. Currently a NOP" */ + klogctl(1, NULL, 0); } -#define OPT_LEVEL 1 -#define OPT_FOREGROUND 2 +static void klogd_setloglevel(int lvl) +{ + /* "printk() prints a message on the console only if it has a loglevel + * less than console_loglevel". Here we set console_loglevel = lvl. */ + klogctl(8, NULL, lvl); +} -#define KLOGD_LOGBUF_SIZE 4096 +static int klogd_read(char *bufp, int len) +{ + /* "2 -- Read from the log." */ + return klogctl(2, bufp, len); +} +# define READ_ERROR "klogctl(2) error" -int klogd_main(int argc, char **argv) +static void klogd_close(void) { - RESERVE_CONFIG_BUFFER(log_buffer, KLOGD_LOGBUF_SIZE); - int console_log_level = -1; - int priority = LOG_INFO; - int i, n, lastc; - char *start; + /* FYI: cmd 7 is equivalent to setting console_loglevel to 7 + * via klogctl(8, NULL, 7). */ + klogctl(7, NULL, 0); /* "7 -- Enable printk's to console" */ + klogctl(0, NULL, 0); /* "0 -- Close the log. Currently a NOP" */ +} +#else - { - unsigned long opt; +# ifndef _PATH_KLOG +# ifdef __GNU__ +# define _PATH_KLOG "/dev/klog" +# else +# error "your system's _PATH_KLOG is unknown" +# endif +# endif +# define PATH_PRINTK "/proc/sys/kernel/printk" - /* do normal option parsing */ - opt = bb_getopt_ulflags(argc, argv, "c:n", &start); +enum { klogfd = 3 }; - if (opt & OPT_LEVEL) { - /* Valid levels are between 1 and 8 */ - console_log_level = bb_xgetlarg(start, 10, 1, 8); - } +static void klogd_open(void) +{ + int fd = xopen(_PATH_KLOG, O_RDONLY); + xmove_fd(fd, klogfd); +} + +static void klogd_setloglevel(int lvl) +{ + FILE *fp = fopen_or_warn(PATH_PRINTK, "w"); + if (fp) { + /* This changes only first value: + * "messages with a higher priority than this + * [that is, with numerically lower value] + * will be printed to the console". + * The other three values in this pseudo-file aren't changed. + */ + fprintf(fp, "%u\n", lvl); + fclose(fp); + } +} + +static int klogd_read(char *bufp, int len) +{ + return read(klogfd, bufp, len); +} +# define READ_ERROR "read error" + +static void klogd_close(void) +{ + klogd_setloglevel(7); + if (ENABLE_FEATURE_CLEAN_UP) + close(klogfd); +} - if (!(opt & OPT_FOREGROUND)) { -#ifdef BB_NOMMU - vfork_daemon_rexec(0, 1, argc, argv, "-n"); -#else - xdaemon(0, 1); #endif - } + +#define log_buffer bb_common_bufsiz1 +enum { + KLOGD_LOGBUF_SIZE = COMMON_BUFSIZE, + OPT_LEVEL = (1 << 0), + OPT_FOREGROUND = (1 << 1), +}; + +/* TODO: glibc openlog(LOG_KERN) reverts to LOG_USER instead, + * because that's how they interpret word "default" + * in the openlog() manpage: + * LOG_USER (default) + * generic user-level messages + * and the fact that LOG_KERN is a constant 0. + * glibc interprets it as "0 in openlog() call means 'use default'". + * I think it means "if openlog wasn't called before syslog() is called, + * use default". + * Convincing glibc maintainers otherwise is, as usual, nearly impossible. + * Should we open-code syslog() here to use correct facility? + */ + +int klogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; +int klogd_main(int argc UNUSED_PARAM, char **argv) +{ + int i = 0; + char *opt_c; + int opt; + int used; + + setup_common_bufsiz(); + + opt = getopt32(argv, "c:n", &opt_c); + if (opt & OPT_LEVEL) { + /* Valid levels are between 1 and 8 */ + i = xatou_range(opt_c, 1, 8); } + if (!(opt & OPT_FOREGROUND)) { + bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv); + } + + logmode = LOGMODE_SYSLOG; + /* klogd_open() before openlog(), since it might use fixed fd 3, + * and openlog() also may use the same fd 3 if we swap them: + */ + klogd_open(); openlog("kernel", 0, LOG_KERN); + /* + * glibc problem: for some reason, glibc changes LOG_KERN to LOG_USER + * above. The logic behind this is that standard + * http://pubs.opengroup.org/onlinepubs/9699919799/functions/syslog.html + * says the following about openlog and syslog: + * "LOG_USER + * Messages generated by arbitrary processes. + * This is the default facility identifier if none is specified." + * + * I believe glibc misinterpreted this text as "if openlog's + * third parameter is 0 (=LOG_KERN), treat it as LOG_USER". + * Whereas it was meant to say "if *syslog* is called with facility + * 0 in its 1st parameter without prior call to openlog, then perform + * implicit openlog(LOG_USER)". + * + * As a result of this, eh, feature, standard klogd was forced + * to open-code its own openlog and syslog implementation (!). + * + * Note that prohibiting openlog(LOG_KERN) on libc level does not + * add any security: any process can open a socket to "/dev/log" + * and write a string "<0>Voila, a LOG_KERN + LOG_EMERG message" + * + * Google code search tells me there is no widespread use of + * openlog("foo", 0, 0), thus fixing glibc won't break userspace. + * + * The bug against glibc was filed: + * bugzilla.redhat.com/show_bug.cgi?id=547000 + */ + + if (i) + klogd_setloglevel(i); - /* Set up sig handlers */ - signal(SIGINT, klogd_signal); - signal(SIGKILL, klogd_signal); - signal(SIGTERM, klogd_signal); signal(SIGHUP, SIG_IGN); + /* We want klogd_read to not be restarted, thus _norestart: */ + bb_signals_recursive_norestart(BB_FATAL_SIGS, record_signo); - /* "Open the log. Currently a NOP." */ - klogctl(1, NULL, 0); + syslog(LOG_NOTICE, "klogd started: %s", bb_banner); - /* Set level of kernel console messaging.. */ - if (console_log_level != -1) - klogctl(8, NULL, console_log_level); + write_pidfile(CONFIG_PID_FILE_PATH "/klogd.pid"); - syslog(LOG_NOTICE, "klogd started: %s", BB_BANNER); + used = 0; + while (!bb_got_signal) { + int n; + int priority; + char *start; - while (1) { - /* Use kernel syscalls */ - memset(log_buffer, '\0', KLOGD_LOGBUF_SIZE); - n = klogctl(2, log_buffer, KLOGD_LOGBUF_SIZE); + start = log_buffer + used; + n = klogd_read(start, KLOGD_LOGBUF_SIZE-1 - used); if (n < 0) { if (errno == EINTR) continue; - syslog(LOG_ERR, "klogd: Error from sys_sycall: %d - %m.\n", - errno); - exit(EXIT_FAILURE); + bb_perror_msg(READ_ERROR); + break; } + start[n] = '\0'; + + /* Process each newline-terminated line in the buffer */ + start = log_buffer; + while (1) { + char *newline = strchrnul(start, '\n'); + + if (*newline == '\0') { + /* This line is incomplete */ - /* klogctl buffer parsing modelled after code in dmesg.c */ - start = &log_buffer[0]; - lastc = '\0'; - for (i = 0; i < n; i++) { - if (lastc == '\0' && log_buffer[i] == '<') { - priority = 0; - i++; - while (log_buffer[i] >= '0' && log_buffer[i] <= '9') { - priority = priority * 10 + (log_buffer[i] - '0'); - i++; + /* move it to the front of the buffer */ + overlapping_strcpy(log_buffer, start); + used = newline - start; + if (used < KLOGD_LOGBUF_SIZE-1) { + /* buffer isn't full */ + break; } - if (log_buffer[i] == '>') - i++; - start = &log_buffer[i]; + /* buffer is full, log it anyway */ + used = 0; + newline = NULL; + } else { + *newline++ = '\0'; } - if (log_buffer[i] == '\n') { - log_buffer[i] = '\0'; /* zero terminate this message */ - syslog(priority, "%s", start); - start = &log_buffer[i + 1]; - priority = LOG_INFO; + + /* Extract the priority */ + priority = LOG_INFO; + if (*start == '<') { + start++; + if (*start) { + char *end; + priority = strtoul(start, &end, 10); + if (*end == '>') + end++; + start = end; + } } - lastc = log_buffer[i]; + /* Log (only non-empty lines) */ + if (*start) + syslog(priority, "%s", start); + + if (!newline) + break; + start = newline; } } - if (ENABLE_FEATURE_CLEAN_UP) - RELEASE_CONFIG_BUFFER(log_buffer); - return EXIT_SUCCESS; + klogd_close(); + syslog(LOG_NOTICE, "klogd: exiting"); + remove_pidfile(CONFIG_PID_FILE_PATH "/klogd.pid"); + if (bb_got_signal) + kill_myself_with_sig(bb_got_signal); + return EXIT_FAILURE; }