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authorDenys Vlasenko <vda.linux@googlemail.com>2011-03-07 09:57:26 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2011-03-07 09:57:26 (GMT)
commit8b6b472f4edd701ac3b25d4a0c89ab506e09e0bb (patch)
tree17e9bbaad2543bb15e9e3783fc5323592fa2065b
parente6bb8d339fc6897c85c63a5a62d7c4402f7b1a54 (diff)
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klogd: fix the problem of delayed handling of ^C and SIGTERM
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--sysklogd/klogd.c31
1 files changed, 30 insertions, 1 deletions
diff --git a/sysklogd/klogd.c b/sysklogd/klogd.c
index 0d4c257..db32065 100644
--- a/sysklogd/klogd.c
+++ b/sysklogd/klogd.c
@@ -150,12 +150,41 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
*/
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);
- bb_signals(BB_FATAL_SIGS, record_signo);
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);