Date: Wed, 3 Oct 2001 22:13:10 -0700 From: "Crist J. Clark" <cristjc@earthlink.net> To: freebsd-audit@freebsd.org Subject: dmesg.boot Gets Overwritten without Reboot Message-ID: <20011003221310.Q8391@blossom.cjclark.org>
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This is a potential fix for bin/24592. The problem is that the file
/var/run/dmesg.boot is overwritten unconditionally in /etc/rc. This
occurs whether we are really freshly booting the kernel or coming up
from single-user mode. I do not believe that the dmesg.boot file
should be overwritten if we are coming up from single-user mode. There
is a very good chance the boot messages have fallen out of the
dmesg(8) buffer by now and we are overwriting the file with whatever
happens to be in the buffer. This is not what we want to have in the
dmesg.boot file.
The basic fix for this is to only write dmesg(8) to the
/var/run/dmesg.boot file if we are in an "autoboot." However, there is
some ugliness in actually getting this done since we have to
temporarily store dmesg.boot elsewhere when /var/run is purged.
There is one basic problem with this approach. If we freshly boot the
system and go to sigle user before going to multi-user mode, we will
not get a new dmesg.boot. When coming from single-user mode to
multi-user mode, I do not know of a way to tell how we got into that
single-user mode whether from a fresh boot or down from multi-user.
But I would rather miss saving the dmesg(8) in this case rather than
overwrite it with gibberish in the second. Others may disagree.
Any comments on the patch or the concept?
Index: rc
===================================================================
RCS file: /export/ncvs/src/etc/rc,v
retrieving revision 1.283
diff -u -r1.283 rc
--- rc 2001/10/02 12:00:39 1.283
+++ rc 2001/10/04 05:07:44
@@ -339,10 +339,19 @@
clean_var() {
if [ ! -f /var/run/clean_var ]; then
+ # We may wish to save the boot messages
+ if [ -f /var/run/dmesg.boot ]; then
+ mv -f /var/run/dmesg.boot /tmp/dmesg.boot
+ fi
purgedir /var/run /var/spool/lock
rm -rf /var/spool/uucp/.Temp/*
# Keep a copy of the boot messages around
- dmesg >/var/run/dmesg.boot
+ if [ X"$bootmode" = X"autoboot" -o ! -f /tmp/dmesg.boot ]; then
+ dmesg >/var/run/dmesg.boot
+ else
+ mv -f /tmp/dmesg.boot /var/run/dmesg.boot
+ rm -f /tmp/dmesg.boot
+ fi
# And an initial utmp file
(cd /var/run && cp /dev/null utmp && chmod 644 utmp;)
>/var/run/clean_var
--
Crist J. Clark cjclark@alum.mit.edu
cjclark@jhu.edu
cjc@freebsd.org
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