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Fix #48: add option ('-K') to disable kernel logging

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This patch adds support for disabling kernel logging, opensys().  This
is in addition to the character device validation check, and primarily
for use in container use-cases -- where logging kernel is not needed.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
This commit is contained in:
Joachim Wiberg 2022-02-13 23:40:06 +01:00
parent 49b99584a4
commit 29e932008d
2 changed files with 25 additions and 12 deletions
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5
man/syslogd.8
View File

@ -38,7 +38,7 @@
.Nd log systems messages
.Sh SYNOPSIS
.Nm
.Op Fl ?46AdFHknsTtv
.Op Fl ?46AdFHKknsTtv
.Op Fl a Ar addr[/len][:port]
.Op Fl a Ar name[:port]
.Op Fl b Ar addr[:port]
@ -255,6 +255,9 @@ and wants to monitor when and how it exits.
.It Fl H
When logging remote messages use hostname from the message (if supplied)
instead of using address from which the message was received.
.It Fl K
Disable kernel logging. Useful in container use-cases where kernel logs
har handled by the host system.
.It Fl k
Disable the translation of
messages received with facility

32
src/syslogd.c
View File

@ -140,6 +140,7 @@ static int SecureMode; /* when true, receive only unix domain socks */
static int RemoteAddDate; /* Always set the date on remote messages */
static int RemoteHostname; /* Log remote hostname from the message */
static int KernLog = 1; /* Track kernel logs by default */
static int KeepKernFac; /* Keep remotely logged kernel facility */
static int KeepKernTime; /* Keep kernel timestamp, evern after initial read */
@ -255,8 +256,8 @@ static void sys_seqno_save(void)
int usage(int code)
{
printf("Usage:\n"
" syslogd [-46AdFKknsTv?] [-a PEER] [-b NAME] [-f FILE] [-m INTERVAL]\n"
" [-P PID_FILE] [-p SOCK_PATH] [-r SIZE[:NUM]]\n"
" syslogd [-46AdFKknsTtv?] [-a PEER] [-b NAME] [-f FILE] [-m INTERVAL]\n"
" [-P PID_FILE] [-p SOCK_PATH] [-r SIZE[:NUM]]\n"
"Options:\n"
" -4 Force IPv4 only\n"
" -6 Force IPv6 only\n"
@ -285,6 +286,7 @@ int usage(int code)
" -d Enable debug mode, implicitly enables -F to prevent backgrounding\n"
" -F Run in foreground, required when monitored by init(1)\n"
" -f FILE Alternate .conf file, default: %s\n"
" -K Disable kernel logging, useful in container use-cases\n"
" -k Allow logging with facility 'kernel', otherwise remapped to 'user'\n"
" -m MINS Interval between MARK messages, 0 to disable, default: 20 min\n"
" -n Disable DNS query for every request\n"
@ -318,7 +320,7 @@ int main(int argc, char *argv[])
int pflag = 0, bflag = 0;
int ch;
while ((ch = getopt(argc, argv, "46Aa:b:C:dHFf:km:nP:p:r:sTtv?")) != EOF) {
while ((ch = getopt(argc, argv, "46Aa:b:C:dHFf:Kkm:nP:p:r:sTtv?")) != EOF) {
switch ((char)ch) {
case '4':
family = PF_INET;
@ -369,6 +371,10 @@ int main(int argc, char *argv[])
RemoteHostname = 1;
break;
case 'K':
KernLog = 0;
break;
case 'k': /* keep remote kern fac */
KeepKernFac = 1;
break;
@ -457,14 +463,17 @@ int main(int argc, char *argv[])
* /dev/kmsg and fall back to _PROC_KLOG, which on GLIBC
* systems is /proc/kmsg, and /dev/klog on *BSD.
*/
sys_seqno_load();
if (opensys("/dev/kmsg")) {
if (opensys(_PATH_KLOG))
warn("Kernel logging disabled, failed opening %s", _PATH_KLOG);
else
if (KernLog) {
sys_seqno_load();
if (opensys("/dev/kmsg")) {
if (opensys(_PATH_KLOG))
warn("Kernel logging disabled, failed opening %s",
_PATH_KLOG);
else
kern_console_off();
} else
kern_console_off();
} else
kern_console_off();
}
consfile.f_type = F_CONSOLE;
strlcpy(consfile.f_un.f_fname, ctty, sizeof(consfile.f_un.f_fname));
@ -523,7 +532,8 @@ int main(int argc, char *argv[])
if (rc < 0 && errno != EINTR)
ERR("select()");
sys_seqno_save();
if (KernLog)
sys_seqno_save();
}
}