€•@      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ /translations/zh_CN/security/sak”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/zh_TW/security/sak”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/it_IT/security/sak”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/ja_JP/security/sak”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/ko_KR/security/sak”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/sp_SP/security/sak”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒ)Linux Secure Attention Key (SAK) handling”h]”hŒ)Linux Secure Attention Key (SAK) handling”…””}”(hh¨hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hh£hžhhŸŒ:/var/lib/git/docbuild/linux/Documentation/security/sak.rst”h KubhŒ
field_list”“”)”}”(hhh]”(hŒfield”“”)”}”(hhh]”(hŒ
field_name”“”)”}”(hŒDate”h]”hŒDate”…””}”(hhÃhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÁhh¾hŸh¶h K ubhŒ
field_body”“”)”}”(hŒ18 March 2001”h]”hŒ	paragraph”“”)”}”(hhÕh]”hŒ18 March 2001”…””}”(hhÙhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h KhhÓubah}”(h]”h ]”h"]”h$]”h&]”uh1hÑhh¾ubeh}”(h]”h ]”h"]”h$]”h&]”uh1h¼hŸh¶h Khh¹hžhubh½)”}”(hhh]”(hÂ)”}”(hŒAuthor”h]”hŒAuthor”…””}”(hhõhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÁhhòhŸh¶h K ubhÒ)”}”(hŒAndrew Morton
”h]”hØ)”}”(hŒAndrew Morton”h]”hŒAndrew Morton”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hÑhhòubeh}”(h]”h ]”h"]”h$]”h&]”uh1h¼hŸh¶h Khh¹hžhubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hh£hžhhŸh¶h KubhØ)”}”(hXE  An operating system's Secure Attention Key is a security tool which is
provided as protection against trojan password capturing programs.  It
is an undefeatable way of killing all programs which could be
masquerading as login applications.  Users need to be taught to enter
this key sequence before they log in to the system.”h]”hXG  An operating systemâ€™s Secure Attention Key is a security tool which is
provided as protection against trojan password capturing programs.  It
is an undefeatable way of killing all programs which could be
masquerading as login applications.  Users need to be taught to enter
this key sequence before they log in to the system.”…””}”(hj'  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khh£hžhubhØ)”}”(hŒÙFrom the PC keyboard, Linux has two similar but different ways of
providing SAK.  One is the ALT-SYSRQ-K sequence.  You shouldn't use
this sequence.  It is only available if the kernel was compiled with
sysrq support.”h]”hŒÛFrom the PC keyboard, Linux has two similar but different ways of
providing SAK.  One is the ALT-SYSRQ-K sequence.  You shouldnâ€™t use
this sequence.  It is only available if the kernel was compiled with
sysrq support.”…””}”(hj5  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khh£hžhubhØ)”}”(hŒžThe proper way of generating a SAK is to define the key sequence using
``loadkeys``.  This will work whether or not sysrq support is compiled
into the kernel.”h]”(hŒGThe proper way of generating a SAK is to define the key sequence using
”…””}”(hjC  hžhhŸNh NubhŒliteral”“”)”}”(hŒ``loadkeys``”h]”hŒloadkeys”…””}”(hjM  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jK  hjC  ubhŒK.  This will work whether or not sysrq support is compiled
into the kernel.”…””}”(hjC  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khh£hžhubhØ)”}”(hŒÕSAK works correctly when the keyboard is in raw mode.  This means that
once defined, SAK will kill a running X server.  If the system is in
run level 5, the X server will restart.  This is what you want to
happen.”h]”hŒÕSAK works correctly when the keyboard is in raw mode.  This means that
once defined, SAK will kill a running X server.  If the system is in
run level 5, the X server will restart.  This is what you want to
happen.”…””}”(hje  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khh£hžhubhØ)”}”(hŒ¡What key sequence should you use? Well, CTRL-ALT-DEL is used to reboot
the machine.  CTRL-ALT-BACKSPACE is magical to the X server.  We'll
choose CTRL-ALT-PAUSE.”h]”hŒ£What key sequence should you use? Well, CTRL-ALT-DEL is used to reboot
the machine.  CTRL-ALT-BACKSPACE is magical to the X server.  Weâ€™ll
choose CTRL-ALT-PAUSE.”…””}”(hjs  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khh£hžhubhØ)”}”(hŒ8In your rc.sysinit (or rc.local) file, add the command::”h]”hŒ7In your rc.sysinit (or rc.local) file, add the command:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h K hh£hžhubhŒliteral_block”“”)”}”(hŒ4echo "control alt keycode 101 = SAK" | /bin/loadkeys”h]”hŒ4echo "control alt keycode 101 = SAK" | /bin/loadkeys”…””}”hj‘  sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1j  hŸh¶h K"hh£hžhubhØ)”}”(hŒ=And that's it!  Only the superuser may reprogram the SAK key.”h]”hŒ?And thatâ€™s it!  Only the superuser may reprogram the SAK key.”…””}”(hj¡  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h K$hh£hžhubhŒnote”“”)”}”(hXW  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.

   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::

      # 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::

      # 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:

   Old::

      daemon gpm

   New::

      daemon gpm < /dev/null

   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::

      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.”h]”hŒenumerated_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒ‡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.

”h]”hØ)”}”(hŒ…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.”h]”hŒ‰Linux SAK is said to be not a â€œtrue SAKâ€ as is required by
systems which implement C2 level security.  This author does not
know why.”…””}”(hjÀ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h K)hj¼  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jº  hj·  ubj»  )”}”(hXi  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!

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::

   # 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:

Old::

   daemon gpm

New::

   daemon gpm < /dev/null

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::

   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.”h]”(hØ)”}”(hŒNOn the PC keyboard, SAK kills all applications which have
/dev/console opened.”h]”hŒNOn the PC keyboard, SAK kills all applications which have
/dev/console opened.”…””}”(hjØ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h K.hjÔ  ubhØ)”}”(hŒÞUnfortunately this includes a number of things which you don't
actually want killed.  This is because these applications are
incorrectly holding /dev/console open.  Be sure to complain to your
Linux distributor about this!”h]”hŒàUnfortunately this includes a number of things which you donâ€™t
actually want killed.  This is because these applications are
incorrectly holding /dev/console open.  Be sure to complain to your
Linux distributor about this!”…””}”(hjæ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h K1hjÔ  ubhØ)”}”(hŒIYou can identify processes which will be killed by SAK with the
command::”h]”hŒHYou can identify processes which will be killed by SAK with the
command:”…””}”(hjô  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h K6hjÔ  ubj  )”}”(hŒ# ls -l /proc/[0-9]*/fd/* | grep console
l-wx------    1 root     root           64 Mar 18 00:46 /proc/579/fd/0 -> /dev/console”h]”hŒ# ls -l /proc/[0-9]*/fd/* | grep console
l-wx------    1 root     root           64 Mar 18 00:46 /proc/579/fd/0 -> /dev/console”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”jŸ  j   uh1j  hŸh¶h K9hjÔ  ubhØ)”}”(hŒThen::”h]”hŒThen:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h K<hjÔ  ubj  )”}”(hŒ\# ps aux|grep 579
root       579  0.0  0.1  1088  436 ?        S    00:43   0:00 gpm -t ps/2”h]”hŒ\# ps aux|grep 579
root       579  0.0  0.1  1088  436 ?        S    00:43   0:00 gpm -t ps/2”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”jŸ  j   uh1j  hŸh¶h K>hjÔ  ubhØ)”}”(hŒ½So ``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:”h]”(hŒSo ”…””}”(hj,  hžhhŸNh NubjL  )”}”(hŒ``gpm``”h]”hŒgpm”…””}”(hj4  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jK  hj,  ubhŒ³ will be killed by SAK.  This is a bug in gpm.  It should
be closing standard input.  You can work around this by finding the
initscript which launches gpm and changing it thusly:”…””}”(hj,  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h KAhjÔ  ubhØ)”}”(hŒOld::”h]”hŒOld:”…””}”(hjL  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h KEhjÔ  ubj  )”}”(hŒ
daemon gpm”h]”hŒ
daemon gpm”…””}”hjZ  sbah}”(h]”h ]”h"]”h$]”h&]”jŸ  j   uh1j  hŸh¶h KGhjÔ  ubhØ)”}”(hŒNew::”h]”hŒNew:”…””}”(hjh  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h KIhjÔ  ubj  )”}”(hŒdaemon gpm < /dev/null”h]”hŒdaemon gpm < /dev/null”…””}”hjv  sbah}”(h]”h ]”h"]”h$]”h&]”jŸ  j   uh1j  hŸh¶h KKhjÔ  ubhØ)”}”(hŒIVixie cron also seems to have this problem, and needs the same treatment.”h]”hŒIVixie cron also seems to have this problem, and needs the same treatment.”…””}”(hj„  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h KMhjÔ  ubhØ)”}”(hŒgAlso, one prominent Linux distribution has the following three
lines in its rc.sysinit and rc scripts::”h]”hŒfAlso, one prominent Linux distribution has the following three
lines in its rc.sysinit and rc scripts:”…””}”(hj’  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h KOhjÔ  ubj  )”}”(hŒexec 3<&0
exec 4>&1
exec 5>&2”h]”hŒexec 3<&0
exec 4>&1
exec 5>&2”…””}”hj   sbah}”(h]”h ]”h"]”h$]”h&]”jŸ  j   uh1j  hŸh¶h KRhjÔ  ubhØ)”}”(hX(  These commands cause **all** daemons which are launched by the
initscripts to have file descriptors 3, 4 and 5 attached to
/dev/console.  So SAK kills them all.  A workaround is to simply
delete these lines, but this may cause system management
applications to malfunction - test everything well.”h]”(hŒThese commands cause ”…””}”(hj®  hžhhŸNh NubhŒstrong”“”)”}”(hŒ**all**”h]”hŒall”…””}”(hj¸  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j¶  hj®  ubhX   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.”…””}”(hj®  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h KVhjÔ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jº  hj·  ubeh}”(h]”h ]”h"]”h$]”h&]”Œenumtype”Œarabic”Œprefix”hŒsuffix”Œ.”uh1jµ  hj±  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j¯  hh£hžhhŸNh Nubeh}”(h]”Œ'linux-secure-attention-key-sak-handling”ah ]”h"]”Œ)linux secure attention key (sak) handling”ah$]”h&]”uh1h¡hhhžhhŸh¶h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h¶uh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¦NŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
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id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nhžhub.