Re: 2.6.13: can kill X server but readlink of /proc/<pid>/exe et. al. says EACCES. feature?

[viro]

On Tue, Sep 06, 2005 at 07:53:49PM +0200, Frank van Maarseveen wrote:
> While I have access to /proc/<pid>, readlink fails with EACCES on
> 
> 	/proc/<pid>/exe
> 	/proc/<pid>/cwd
> 	/proc/<pid>/root
> 
> even when I own <pid> though it runs with a different effective/saved/fs
> uid such as the X server. This is a bit uncomfortable and doesn't
> seem right.
> 
> Or is this to make /proc mounting inside a chroot jail safe?

suid-root task does chdir() to place you shouldn't be able to access.
You do cd /proc/<pid>/cwd and get there anyway.  Bad Things Happen...
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