summaryrefslogtreecommitdiff
path: root/Documentation/SAK.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/SAK.txt')
-rw-r--r--Documentation/SAK.txt65
1 files changed, 34 insertions, 31 deletions
diff --git a/Documentation/SAK.txt b/Documentation/SAK.txt
index 74be14679ed8..260e1d3687bd 100644
--- a/Documentation/SAK.txt
+++ b/Documentation/SAK.txt
@@ -1,5 +1,9 @@
-Linux 2.4.2 Secure Attention Key (SAK) handling
-18 March 2001, Andrew Morton
+=========================================
+Linux Secure Attention Key (SAK) handling
+=========================================
+
+:Date: 18 March 2001
+:Author: Andrew Morton
An operating system's Secure Attention Key is a security tool which is
provided as protection against trojan password capturing programs. It
@@ -13,7 +17,7 @@ this sequence. It is only available if the kernel was compiled with
sysrq support.
The proper way of generating a SAK is to define the key sequence using
-`loadkeys'. This will work whether or not sysrq support is compiled
+``loadkeys``. This will work whether or not sysrq support is compiled
into the kernel.
SAK works correctly when the keyboard is in raw mode. This means that
@@ -25,64 +29,63 @@ What key sequence should you use? Well, CTRL-ALT-DEL is used to reboot
the machine. CTRL-ALT-BACKSPACE is magical to the X server. We'll
choose CTRL-ALT-PAUSE.
-In your rc.sysinit (or rc.local) file, add the command
+In your rc.sysinit (or rc.local) file, add the command::
echo "control alt keycode 101 = SAK" | /bin/loadkeys
And that's it! Only the superuser may reprogram the SAK key.
-NOTES
-=====
+.. note::
-1: Linux SAK is said to be not a "true SAK" as is required by
- systems which implement C2 level security. This author does not
- know why.
+ 1. Linux SAK is said to be not a "true SAK" as is required by
+ systems which implement C2 level security. This author does not
+ know why.
-2: On the PC keyboard, SAK kills all applications which have
- /dev/console opened.
+ 2. On the PC keyboard, SAK kills all applications which have
+ /dev/console opened.
- Unfortunately this includes a number of things which you don't
- actually want killed. This is because these applications are
- incorrectly holding /dev/console open. Be sure to complain to your
- Linux distributor about this!
+ Unfortunately this includes a number of things which you don't
+ actually want killed. This is because these applications are
+ incorrectly holding /dev/console open. Be sure to complain to your
+ Linux distributor about this!
- You can identify processes which will be killed by SAK with the
- command
+ You can identify processes which will be killed by SAK with the
+ command::
# ls -l /proc/[0-9]*/fd/* | grep console
l-wx------ 1 root root 64 Mar 18 00:46 /proc/579/fd/0 -> /dev/console
- Then:
+ Then::
# ps aux|grep 579
root 579 0.0 0.1 1088 436 ? S 00:43 0:00 gpm -t ps/2
- So `gpm' will be killed by SAK. This is a bug in gpm. It should
- be closing standard input. You can work around this by finding the
- initscript which launches gpm and changing it thusly:
+ So ``gpm`` will be killed by SAK. This is a bug in gpm. It should
+ be closing standard input. You can work around this by finding the
+ initscript which launches gpm and changing it thusly:
- Old:
+ Old::
daemon gpm
- New:
+ New::
daemon gpm < /dev/null
- Vixie cron also seems to have this problem, and needs the same treatment.
+ Vixie cron also seems to have this problem, and needs the same treatment.
- Also, one prominent Linux distribution has the following three
- lines in its rc.sysinit and rc scripts:
+ Also, one prominent Linux distribution has the following three
+ lines in its rc.sysinit and rc scripts::
exec 3<&0
exec 4>&1
exec 5>&2
- These commands cause *all* daemons which are launched by the
- initscripts to have file descriptors 3, 4 and 5 attached to
- /dev/console. So SAK kills them all. A workaround is to simply
- delete these lines, but this may cause system management
- applications to malfunction - test everything well.
+ These commands cause **all** daemons which are launched by the
+ initscripts to have file descriptors 3, 4 and 5 attached to
+ /dev/console. So SAK kills them all. A workaround is to simply
+ delete these lines, but this may cause system management
+ applications to malfunction - test everything well.