On Thu, Oct 04, 2012 at 12:03:54PM -0400, Nick Bowler wrote: > On 2012-10-04 08:49 -0700, Kees Cook wrote: > > On Thu, Oct 04, 2012 at 09:35:04AM -0400, Nick Bowler wrote: > > > On 2012-10-03 13:54 -0700, Linus Torvalds wrote: > > > > On Wed, Oct 3, 2012 at 1:49 PM, Kees Cook <k...@outflux.net> wrote: > > > > > I think the benefits of this being on by default outweigh glitches > > > > > like this. Based on Nick's email, it looks like a directory tree of > > > > > his > > > > > own creation. > > > > > > > > I agree that *one* report like this doesn't necessarily mean that we > > > > need to turn it off, if Nick is happy to just fix up his script and > > > > it's all local. > > > > > > > > However, I suspect we'll see more. And once that happens, we're not > > > > going to keep a default that breaks peoples old scripts, and we're > > > > going to have to rely on distributions (or users) explicitly setting > > > > it. > > > > > > Yes, it is a directory of my own creation, intended as a place for users > > > (read: me) to stick stuff on the local disk as opposed to on NFS. It's > > > pretty trivial for me to fixup everything to not need this symlink > > > anymore (and I suspect it is the only offender); I just created the > > > symlink in the first place so that I wouldn't have to change anything > > > else. > > > > > > (While on /this/ machine I created the directory, I have used shared lab > > > machines with a similar setup). > > > > > > The thing that bothers me most about all this is that it's basically > > > impossible to see why things are failing without digging through the git > > > tree or posting to the mailing list (or recalling earlier mailing list > > > discussions about the restriction, as I vaguely do now). You just > > > suddenly get "permission denied" errors when all the permissions > > > involved look fine. As far as I know, the owner, group and mode of > > > symlinks have always been completely meaningless. Upgrade to 3.6, and > > > they're suddenly meaningful in extremely non-obvious ways. > > > > FWIW, there should have been an audit message about it in dmesg. > > There were zero messages in the kernel log. > > # dmesg -C > # cd /tmp > # mkdir testdir > # ln -s testdir testlink > # chown -h nobody testlink > # cd testlink > cd: permission denied: testlink > # dmesg > (no output)
Well that's sad. :( Two situations I can think of for that: - the kernel wasn't build with CONFIG_AUDIT - auditd is running and hiding the notices in some other log file -Kees -- Kees Cook @outflux.net -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
