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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 | /* vi: set sw=4 ts=4: */ /* * Mini klogd implementation for busybox * * Copyright (C) 2001 by Gennady Feldman <gfeldman@gena01.com>. * Changes: Made this a standalone busybox module which uses standalone * syslog() client interface. * * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org> * * Copyright (C) 2000 by Karl M. Hegbloom <karlheg@debian.org> * * "circular buffer" Copyright (C) 2000 by Gennady Feldman <gfeldman@gena01.com> * * Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001 * * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ //config:config KLOGD //config: bool "klogd (5.7 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'. //applet:IF_KLOGD(APPLET(klogd, BB_DIR_SBIN, BB_SUID_DROP)) //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 <syslog.h> /* 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 <sys/klog.h> static void klogd_open(void) { /* "Open the log. Currently a NOP" */ klogctl(1, NULL, 0); } 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); } static int klogd_read(char *bufp, int len) { /* "2 -- Read from the log." */ return klogctl(2, bufp, len); } # define READ_ERROR "klogctl(2) error" static void klogd_close(void) { /* 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 # 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" enum { klogfd = 3 }; 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); } #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); signal(SIGHUP, SIG_IGN); /* We want klogd_read to not be restarted, thus _norestart: */ bb_signals_recursive_norestart(BB_FATAL_SIGS, record_signo); syslog(LOG_NOTICE, "klogd started: %s", bb_banner); write_pidfile_std_path_and_ext("klogd"); used = 0; while (!bb_got_signal) { int n; int priority; char *start; start = log_buffer + used; n = klogd_read(start, KLOGD_LOGBUF_SIZE-1 - used); if (n < 0) { if (errno == EINTR) continue; bb_simple_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 */ /* 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; } /* buffer is full, log it anyway */ used = 0; newline = NULL; } else { *newline++ = '\0'; } /* Extract the priority */ priority = LOG_INFO; if (*start == '<') { start++; if (*start) { char *end; priority = strtoul(start, &end, 10); if (*end == '>') end++; start = end; } } /* Log (only non-empty lines) */ if (*start) syslog(priority, "%s", start); if (!newline) break; start = newline; } } klogd_close(); syslog(LOG_NOTICE, "klogd: exiting"); remove_pidfile_std_path_and_ext("klogd"); if (bb_got_signal) kill_myself_with_sig(bb_got_signal); return EXIT_FAILURE; } |