Messages in this thread | | | From | Andy Lutomirski <> | Date | Tue, 22 Apr 2014 08:24:00 -0700 | Subject | Re: [RFC 2/2] fs,proc: Respect FMODE_WRITE when opening /proc/pid/fd/N |
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On Tue, Apr 22, 2014 at 8:19 AM, David Herrmann <dh.herrmann@gmail.com> wrote: > Hi > > On Tue, Apr 22, 2014 at 4:31 PM, Pavel Machek <pavel@ucw.cz> wrote: >> Such as here? >> >> http://www.securityfocus.com/archive/1/507386 > > Thanks, that's the first real example someone mentioned. > > Quoted from your link: > >> The reopen does check the inode permission, but it does not require >> you have any reachable path to the file. Someone _might_ use that as >> a traditional unix security mechanism, but if so it's probably quite rare. > > In other words, the bug you describe is that /proc/pid/fd/ allows > access to objects without a reachable path to the only _real_ > filesystem link. But isn't the same true for openat()?
I don't think so. openat doesn't work on fds for things that aren't directories.
--Andy
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