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Tasklist

FS#13769 - [procps] magic-sysrq key disabled by default

Attached to Project: Arch Linux
Opened by Xavier (shining) - Thursday, 12 March 2009, 12:06 GMT
Last edited by Eric Belanger (Snowman) - Thursday, 12 March 2009, 20:54 GMT
Task Type Bug Report
Category Packages: Core
Status Closed
Assigned To Eric Belanger (Snowman)
Architecture All
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 1
Private No

Details

$ grep sysrq /etc/sysctl.conf
# Disable the magic-sysrq key
kernel.sysrq = 0

This setting in arch has apparently been there since sysctl.conf was introduced, 3,5 years ago :
http://repos.archlinux.org/viewvc.cgi/core/base/procps/sysctl.conf?root=core&view=log

Is it needed to change the default behavior (sysrq enabled)? What this made for security concerns?
http://en.wikipedia.org/wiki/Magic_SysRq_key#Security_Concerns

If that's the case, could this aspect be mentioned at least in sysctl.conf :
# Disable the magic-sysrq key for security reasons
kernel.sysrq = 0

Of course, the need of this key is not usual, but over the past three years, I am sure I had several times a need for it, and probably it never worked because of this setting, and I just never realized that.
I thought the kernel was too badly locked for this key to even work, or something like that.
This task depends upon

Closed by  Eric Belanger (Snowman)
Thursday, 12 March 2009, 20:54 GMT
Reason for closing:  Not a bug
Comment by Xavier (shining) - Thursday, 12 March 2009, 18:17 GMT
I guess this was more a feature request than a bug report.
I opened it after reading this thread and making this post :
http://bbs.archlinux.org/viewtopic.php?pid=514200#p514200

All other users from that thread seem to be fine with that default behavior, since it's easy to change. Same for several people on IRC.
dhave made a good point that the most important is to have this feature built in the kernel, so that the user can easily switch it on or off.

Anyway it still puzzled me that this nice feature was disabled by default, but I won't complain if this FR is rejected.
Comment by Eric Belanger (Snowman) - Thursday, 12 March 2009, 20:52 GMT
FTR, I just adopted this orphaned packages. Judd is the one who added this sysctl.conf. This option is also disabled in the upstream sysctl.conf so I'll keep it that way. Users can always enable it if they want to; the kernel already support it. I'll just modify the comment in svn.

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