bin/47449: syslogd doesn't honor mesg n

[dholland%netbsd.org@localhost]

>Number:         47449
>Category:       bin
>Synopsis:       syslogd doesn't honor mesg n
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jan 15 05:25:00 +0000 2013
>Originator:     David A. Holland
>Release:        NetBSD 6.99.16 (20120115)
>Organization:
>Environment:
System: NetBSD macaran 6.99.11 NetBSD 6.99.11 (MACARAN) #15: Mon Oct 15 
21:24:31 EDT 2012  dholland@macaran:/usr/src/sys/arch/amd64/compile/MACARAN 
amd64
Architecture: x86_64
Machine: amd64
>Description:

syslogd does not honor mesg n (g+w permission) on the ttys of users it
sends logs to.

This is a nuisance sometimes.

>How-To-Repeat:

Create a test user, add it as a destination in syslog.conf (e.g.
cron.*  testuser), log in, set mesg n, and watch the messages roll in
regardless.

>Fix:

As syslogd runs as root it needs to explicitly check for g+w
permission, instead of just using the same tty message code as other
things and assuming it'll get EACCES when mesg n is set.

Probably it should also override mesg n for LOG_EMERG messages, which
are traditionally walled to everyone.