Re: [PATCH] Reset current->pdeath_signal on SUID binary execution

[Michael Kerrisk <mtk-manpages@gmx.net>]

Marcel,

>> the attached patch fixes a flaw in the "parent process death signal"
>> when executing SUID binaries. An unprivileged user may send arbitrary
>> signal to a child process even if it is running with higher privileges.
>>
>> The idea to fix this issue is to reset pdeath_signal not only on fork,
>> but also on the execution of a SUID binary.
>>
>> Michael, if we fix it this way, then the prctl() manual page should
>> reflect that behavior.
> 
> the patch has been merged into 2.4 and 2.6, so the manual page needs an
> update at some point.

I see your patch at:

http://article.gmane.org/gmane.linux.kernel/571635/match=pdeath%5fsignal+suid+binary+execution

But it's not clear to me in which 2.4.x and 2.6.x versions the change occurred (it isn't in 2.6.23-rc3 -- is it scheduled
for 2.6.23-rc4?).  Can you enlighten me?

Cheers,

Michael

>> From comments it seems that we have to also reset pdeath_signal inside
>> LSM when it comes to capability-raised executes, but I must admit that I
>> got lost there.
> 
> No further comments for this one? I am not familiar enough with it.
> 
> Regards
> 
> Marcel
> 
> 

-- 
Michael Kerrisk
maintainer of Linux man pages Sections 2, 3, 4, 5, and 7

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