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Date: Tue, 21 Jul 2009 19:06:41 +0200 From: Denys Vlasenko <vda.linux@...glemail.com> To: Lennart Poettering <mzxreary@...inter.de> Cc: linux-kernel@...r.kernel.org Subject: Re: Can access to /proc/$PID/exe be relaxed? On Tue, Jul 21, 2009 at 6:52 PM, Lennart Poettering<mzxreary@...inter.de> wrote: > Hi! > > Unless I am mistaken a process currently needs CAP_SYS_PTRACE to read > /proc/$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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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