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authorLinus Torvalds <torvalds@linux-foundation.org>2017-07-15 22:58:58 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-15 22:58:58 +0300
commit486088bc4689f826b80aa317b45ac9e42e8b25ee (patch)
treeadf5847a6119d24da990d9e336f005c4a316e6be /Documentation/SAK.txt
parent52f6c588c77b76d548201470c2a28263a41b462b (diff)
parent43e5f7e1fa66531777c49791014c3124ea9208d8 (diff)
downloadlinux-486088bc4689f826b80aa317b45ac9e42e8b25ee.tar.xz
Merge tag 'standardize-docs' of git://git.lwn.net/linux
Pull documentation format standardization from Jonathan Corbet: "This series converts a number of top-level documents to the RST format without incorporating them into the Sphinx tree. The hope is to bring some uniformity to kernel documentation and, perhaps more importantly, have our existing docs serve as an example of the desired formatting for those that will be added later. Mauro has gone through and fixed up a lot of top-level documentation files to make them conform to the RST format, but without moving or renaming them in any way. This will help when we incorporate the ones we want to keep into the Sphinx doctree, but the real purpose is to bring a bit of uniformity to our documentation and let the top-level docs serve as examples for those writing new ones" * tag 'standardize-docs' of git://git.lwn.net/linux: (84 commits) docs: kprobes.txt: Fix whitespacing tee.txt: standardize document format cgroup-v2.txt: standardize document format dell_rbu.txt: standardize document format zorro.txt: standardize document format xz.txt: standardize document format xillybus.txt: standardize document format vfio.txt: standardize document format vfio-mediated-device.txt: standardize document format unaligned-memory-access.txt: standardize document format this_cpu_ops.txt: standardize document format svga.txt: standardize document format static-keys.txt: standardize document format smsc_ece1099.txt: standardize document format SM501.txt: standardize document format siphash.txt: standardize document format sgi-ioc4.txt: standardize document format SAK.txt: standardize document format rpmsg.txt: standardize document format robust-futexes.txt: standardize document format ...
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.