prelink should not mess with running executables

[Sam Varshavchik]

Garrett Holmstrom writes:

> On 2012-07-15 15:00, Sam Varshavchik wrote:
>> Benny Amorsen writes:
>>> Perhaps it's just me, but why would the daemon stat /proc/self/exe? I
>>> presume prelink writes a new file and renames into place as a proper
>>> Unix program should, which still leaves the original program intact on
>>> disk until the last open file descriptor referring to it is gone.
>>
>> A means for authenticating a filesystem domain socket's peer. Receive
>> the peer's credentials, then check /proc/pid/exe and /proc/self/exe. If
>> they're same, the daemon is talking to another instance of itself.
>
> Admittedly without knowledge of what daemon you are referring to, how is the  
> file name alone sufficient to be able to determine that something is,  
> indeed, the same program?  My security-sense seems to be tingling.  ;-)

Can you explain how two completely different executables could possibly end  
up having the same absolute pathname?

Unless there's some way this can happen, I'm fairly optimistic that if  
/proc/pid1/exe is the same thing as as /proc/self/exe, you have a fairly  
reasonable level of confidence that pid1 is the same executable as you are.

That is, of course, in absence's of prelink's bull-in-the-china-shop modus  
operandi.


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