* Can access to /proc/$PID/exe be relaxed?
@ 2009-07-21 16:52 Lennart Poettering
2009-07-21 17:06 ` Denys Vlasenko
0 siblings, 1 reply; 3+ messages in thread
From: Lennart Poettering @ 2009-07-21 16:52 UTC (permalink / raw)
To: linux-kernel
Hi!
Unless I am mistaken a process currently needs CAP_SYS_PTRACE to read
/proc/$PID/exe for abritrary processes. Does that make sense? Could
that be relaxed? Is there any reason to limit access to that link at
all? To me the data from /proc/$PID/cmdline seems to be far more
worthy to be protected than /proc/$PID/exe, or am I missing something?
Tbh, looking at the code I don't really get where CAP_SYS_PTRACE seems
to be required, but experimenting from userspace this seems to be the
case.
Lennart
--
Lennart Poettering Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/ GnuPG 0x1A015CC4
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Can access to /proc/$PID/exe be relaxed?
2009-07-21 16:52 Can access to /proc/$PID/exe be relaxed? Lennart Poettering
@ 2009-07-21 17:06 ` Denys Vlasenko
2009-07-21 17:17 ` Lennart Poettering
0 siblings, 1 reply; 3+ messages in thread
From: Denys Vlasenko @ 2009-07-21 17:06 UTC (permalink / raw)
To: Lennart Poettering; +Cc: linux-kernel
On Tue, Jul 21, 2009 at 6:52 PM, Lennart Poettering<mzxreary@0pointer.de> wrote:
> Hi!
>
> Unless I am mistaken a process currently needs CAP_SYS_PTRACE to read
> /proc/$PID/exe for abritrary processes.
You mean "readlink'?
> Does that make sense? Could
> that be relaxed? Is there any reason to limit access to that link at
> all? To me the data from /proc/$PID/cmdline seems to be far more
> worthy to be protected than /proc/$PID/exe, or am I missing something?
>
> Tbh, looking at the code I don't really get where CAP_SYS_PTRACE seems
> to be required, but experimenting from userspace this seems to be the
> case.
Another annoying thing is that sometimes processes cannot open
their own /proc/self/fd/N. Example:
# setuidgid 200:200 cat /proc/self/fd/0
cat: /proc/self/fd/0: Permission denied
In real life this happened when I wanted to redirect apache's
log to stderr. The config directive only allowed redirecting
to a file, so I specified /proc/self/fd/2. It does not work
if apache drops root after startup.
--
vda
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Can access to /proc/$PID/exe be relaxed?
2009-07-21 17:06 ` Denys Vlasenko
@ 2009-07-21 17:17 ` Lennart Poettering
0 siblings, 0 replies; 3+ messages in thread
From: Lennart Poettering @ 2009-07-21 17:17 UTC (permalink / raw)
To: Denys Vlasenko; +Cc: linux-kernel
On Tue, 21.07.09 19:06, Denys Vlasenko (vda.linux@googlemail.com) wrote:
>
> On Tue, Jul 21, 2009 at 6:52 PM, Lennart Poettering<mzxreary@0pointer.de> wrote:
> > Hi!
> >
> > Unless I am mistaken a process currently needs CAP_SYS_PTRACE to read
> > /proc/$PID/exe for abritrary processes.
>
> You mean "readlink'?
Yes.
Lennart
--
Lennart Poettering Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/ GnuPG 0x1A015CC4
^ permalink raw reply [flat|nested] 3+ messages in thread
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2009-07-21 16:52 Can access to /proc/$PID/exe be relaxed? Lennart Poettering
2009-07-21 17:06 ` Denys Vlasenko
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