On Wed, Aug 6, 2014 at 2:57 AM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > > Linus, > > Please pull the for-linus branch from the git tree: > > git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-linus > > HEAD: 344470cac42e887e68cfb5bdfa6171baf27f1eb5 proc: Point /proc/mounts at /proc/thread-self/mounts instead of /proc/self/mounts > > This is a bunch of small changes built against 3.16-rc6. The most > significant change for users is the first patch which makes setns > drmatically faster by removing unneded rcu handling. > > The next chunk of changes are so that "mount -o remount,.." will not > allow the user namespace root to drop flags on a mount set by the system > wide root. Aks this forces read-only mounts to stay read-only, no-dev > mounts to stay no-dev, no-suid mounts to stay no-suid, no-exec mounts to > stay no exec and it prevents unprivileged users from messing with a > mounts atime settings. I have included my test case as the last patch > in this series so people performing backports can verify this change > works correctly. > > The next change fixes a bug in NFS that was discovered while auditing > nsproxy users for the first optimization. Today you can oops the kernel > by reading /proc/fs/nfsfs/{servers,volumes} if you are clever with pid > namespaces. I rebased and fixed the build of the !CONFIG_NFS_FS case > yesterday when a build bot caught my typo. Given that no one to my > knowledge bases anything on my tree fixing the typo in place seems more > responsible that requiring a typo-fix to be backported as well. > > The last change is a small semantic cleanup introducing > /proc/thread-self and pointing /proc/mounts and /proc/net at it. This > prevents several kinds of problemantic corner cases. It is a > user-visible change so it has a minute chance of causing regressions so > the change to /proc/mounts and /proc/net are individual one line commits > that can be trivially reverted. Unfortunately I lost and could not find > the email of the original reporter so he is not credited. From at least > one perspective this change to /proc/net is a refgression fix to allow > pthread /proc/net uses that were broken by the introduction of the network > namespace. > > Eric > > Eric W. Biederman (11): > namespaces: Use task_lock and not rcu to protect nsproxy > mnt: Only change user settable mount flags in remount > mnt: Move the test for MNT_LOCK_READONLY from change_mount_flags into do_remount > mnt: Correct permission checks in do_remount This commit breaks libvirt-lxc. libvirt does in lxcContainerMountBasicFS(): /* * We can't immediately set the MS_RDONLY flag when mounting filesystems * because (in at least some kernel versions) this will propagate back * to the original mount in the host OS, turning it readonly too. Thus * we mount the filesystem in read-write mode initially, and then do a * separate read-only bind mount on top of that. */ bindOverReadonly = !!(mnt_mflags & MS_RDONLY); VIR_DEBUG("Mount %s on %s type=%s flags=%x", mnt_src, mnt->dst, mnt->type, mnt_mflags & ~MS_RDONLY); if (mount(mnt_src, mnt->dst, mnt->type, mnt_mflags & ~MS_RDONLY, NULL) < 0) { ^^^^ Here it fails for sysfs because with user namespaces we bind the existing /sys into the container and would have to read out all existing mount flags from the current /sys mount. Otherwise mount() fails with EPERM. On my test system /sys is mounted with "rw,nosuid,nodev,noexec,relatime" and libvirt misses the realtime... virReportSystemError(errno, _("Failed to mount %s on %s type %s flags=%x"), mnt_src, mnt->dst, NULLSTR(mnt->type), mnt_mflags & ~MS_RDONLY); goto cleanup; } if (bindOverReadonly && mount(mnt_src, mnt->dst, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) { ^^^ Here it fails because now we'd have to specify all flags as used for the first mount. For the procfs case MS_NOSUID|MS_NOEXEC|MS_NODEV. See lxcBasicMounts[]. In this case the fix is easy, add mnt_mflags to the mount flags. virReportSystemError(errno, _("Failed to re-mount %s on %s flags=%x"), mnt_src, mnt->dst, MS_BIND|MS_REMOUNT|MS_RDONLY); goto cleanup; } -- Thanks, //richard -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list