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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 .Nd log systems messages
.Sh SYNOPSIS .Sh SYNOPSIS
.Nm .Nm
.Op Fl ?46AdFHknsTtv .Op Fl ?46AdFHKknsTtv
.Op Fl a Ar addr[/len][:port] .Op Fl a Ar addr[/len][:port]
.Op Fl a Ar name[:port] .Op Fl a Ar name[:port]
.Op Fl b Ar addr[:port] .Op Fl b Ar addr[:port]
@ -255,6 +255,9 @@ and wants to monitor when and how it exits.
.It Fl H .It Fl H
When logging remote messages use hostname from the message (if supplied) When logging remote messages use hostname from the message (if supplied)
instead of using address from which the message was received. 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 .It Fl k
Disable the translation of Disable the translation of
messages received with facility 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 RemoteAddDate; /* Always set the date on remote messages */
static int RemoteHostname; /* Log remote hostname from the message */ 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 KeepKernFac; /* Keep remotely logged kernel facility */
static int KeepKernTime; /* Keep kernel timestamp, evern after initial read */ static int KeepKernTime; /* Keep kernel timestamp, evern after initial read */
@ -255,8 +256,8 @@ static void sys_seqno_save(void)
int usage(int code) int usage(int code)
{ {
printf("Usage:\n" printf("Usage:\n"
" syslogd [-46AdFKknsTv?] [-a PEER] [-b NAME] [-f FILE] [-m INTERVAL]\n" " syslogd [-46AdFKknsTtv?] [-a PEER] [-b NAME] [-f FILE] [-m INTERVAL]\n"
" [-P PID_FILE] [-p SOCK_PATH] [-r SIZE[:NUM]]\n" " [-P PID_FILE] [-p SOCK_PATH] [-r SIZE[:NUM]]\n"
"Options:\n" "Options:\n"
" -4 Force IPv4 only\n" " -4 Force IPv4 only\n"
" -6 Force IPv6 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" " -d Enable debug mode, implicitly enables -F to prevent backgrounding\n"
" -F Run in foreground, required when monitored by init(1)\n" " -F Run in foreground, required when monitored by init(1)\n"
" -f FILE Alternate .conf file, default: %s\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" " -k Allow logging with facility 'kernel', otherwise remapped to 'user'\n"
" -m MINS Interval between MARK messages, 0 to disable, default: 20 min\n" " -m MINS Interval between MARK messages, 0 to disable, default: 20 min\n"
" -n Disable DNS query for every request\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 pflag = 0, bflag = 0;
int ch; 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) { switch ((char)ch) {
case '4': case '4':
family = PF_INET; family = PF_INET;
@ -369,6 +371,10 @@ int main(int argc, char *argv[])
RemoteHostname = 1; RemoteHostname = 1;
break; break;
case 'K':
KernLog = 0;
break;
case 'k': /* keep remote kern fac */ case 'k': /* keep remote kern fac */
KeepKernFac = 1; KeepKernFac = 1;
break; break;
@ -457,14 +463,17 @@ int main(int argc, char *argv[])
* /dev/kmsg and fall back to _PROC_KLOG, which on GLIBC * /dev/kmsg and fall back to _PROC_KLOG, which on GLIBC
* systems is /proc/kmsg, and /dev/klog on *BSD. * systems is /proc/kmsg, and /dev/klog on *BSD.
*/ */
sys_seqno_load(); if (KernLog) {
if (opensys("/dev/kmsg")) { sys_seqno_load();
if (opensys(_PATH_KLOG)) if (opensys("/dev/kmsg")) {
warn("Kernel logging disabled, failed opening %s", _PATH_KLOG); if (opensys(_PATH_KLOG))
else warn("Kernel logging disabled, failed opening %s",
_PATH_KLOG);
else
kern_console_off();
} else
kern_console_off(); kern_console_off();
} else }
kern_console_off();
consfile.f_type = F_CONSOLE; consfile.f_type = F_CONSOLE;
strlcpy(consfile.f_un.f_fname, ctty, sizeof(consfile.f_un.f_fname)); 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) if (rc < 0 && errno != EINTR)
ERR("select()"); ERR("select()");
sys_seqno_save(); if (KernLog)
sys_seqno_save();
} }
} }