Hello, On Sat, 01 June 2013 Frederic Riss <frederic.r...@gmail.com> wrote: > I had a little application making use of pid and mount namespaces to > isolate some processes on some machines. This all worked well on 3.7 > boxes. A coworker upgraded his machine and noticed that things weren't > working anymore on 3.8. The symptom he noticed is that remounting > /proc inside the namespaced process broke the /proc of the original > namespace. (Remounting /proc is necessary for the pid namespace to be > really effective) > > There is a simple way to reproduce the issue if you have a new enough > util-linux where the unshare utility accepts the --pid option. Try > that: > > bash-4.2$ unshare --pid --mount > -bash-4.2$ sudo mount -t proc /proc /proc > [sudo] password for friss: > sudo: unable to send audit message: Operation not permitted > -bash-4.2$ > > [ The audit failure is already a sign of something going wrong more on > that bellow. ] > Then in another terminal running in the root namesapce: > > bash-4.2$ ls -l /proc/self > ls: cannot read symbolic link /proc/self: No such file or directory > lrwxrwxrwx 1 root root 0 Jun 1 23:37 /proc/self > > As you see, remounting /proc in the private namespace broke the root /proc...
If your coworker updated more than the kernel it might just be that your filesystem is `mount / --make-rshared` on the root mount namespace. E.g. the systmed started doing that some time ago (about a year or so) With `mount --make-rprivate` inside the new namespace before doing anything else mount+pid+ipc+uts(+net) is working fine for me (though I'm changing namespaces using them clone() rather than unshare()) Bruno > Now the namespace isn't functional anyway even if /proc doesn't get remounted: > > bash-4.2$ unshare --pid --mount > -bash-4.2$ id > uid=1001(friss) gid=1001(friss) groups=1001(friss),10(wheel) > -bash-4.2$ id > -bash: fork: Cannot allocate memory > -bash-4.2$ > > It's able to run one process, but every following invocation will > fail. I suppose the audit issue mentioned above is just another > symptom. > > All of this was working fine on 3.7 kernels. I tried it on latest 3.8 > and 3.9 and it fails on both. My application didn't make use of > unshare, but instead forked a new process with the namespacing flags. > The symptoms are identical in both cases. > > Fred. -- 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/
