On 7/15/2015 12:46 PM, Seth Forshee wrote: > These are the first in a larger set of patches that I've been working on > (with help from Eric Biederman) to support mounting ext4 and fuse > filesystems from within user namespaces. I've pushed the full series to: > > git://kernel.ubuntu.com/sforshee/linux.git userns-mounts > > Taking the series as a whole, the strategy is to handle as much of the > heavy lifting as possible in the vfs so the filesystems don't have to > handle weird edge cases. If you look at the full series you'll find that > the changes in ext4 to support user namespace mounts turn out to be > fairly minimal (fuse is a bit more complicated though as it must deal > with translating ids for a userspace process which is running in pid and > user namespaces). > > The patches I'm sending today lay some of the groundwork in the vfs and > related code. They fall into two broad groups: > > 1. Patches 1-2 add s_user_ns and simplify MNT_NODEV handling. These are > pretty straightforward, and Eric has expressed interest in merging > these patches soon. Note that patch 2 won't apply cleanly without > Eric's noexec patches for proc and sys [1]. > > 2. Patches 2-7 tighten down security for mounts with s_user_ns != > &init_user_ns. This includes updates to how file caps and suid are > handled and LSM updates to ignore security labels on superblocks > from non-init namespaces. > > The LSM changes in particular may not be optimal, as I don't have a > lot of familiarity with this code, so I'd be especially appreciative > of review of these changes and suggestions on how to improve them. Lukasz Pawelczyk <l.pawelczyk@xxxxxxxxxxx> proposed LSM support in user namespaces ([RFC] lsm: namespace hooks) that make a whole lot more sense than just turning off the option of using labels on files. Gutting the ability to use MAC in a namespace is a step down the road of making MAC and namespaces incompatible. > > Subsequent patches will update the vfs for id translation, handling > various corner cases, giving privileges to the user namsepace which owns > a superblock, and finally supporting user namespace mounts for ext4 and > fuse. > > Thanks, > Seth > > [1] http://lkml.kernel.org/r/87mvz4yomp.fsf_-_@xxxxxxxxxxxxxxxxxxxxx > > > Andy Lutomirski (1): > fs: Treat foreign mounts as nosuid > > Eric W. Biederman (1): > userns: Simpilify MNT_NODEV handling. > > Seth Forshee (5): > fs: Add user namesapace member to struct super_block > fs: Ignore file caps in mounts from other user namespaces > security: Restrict security attribute updates for userns mounts > selinux: Ignore security labels on user namespace mounts > smack: Don't use security labels for user namespace mounts > > fs/block_dev.c | 2 +- > fs/exec.c | 2 +- > fs/namei.c | 9 ++++++++- > fs/namespace.c | 34 ++++++++++++++++++++-------------- > fs/proc/root.c | 3 ++- > fs/super.c | 38 +++++++++++++++++++++++++++++++++----- > include/linux/fs.h | 9 +++++++++ > include/linux/mount.h | 1 + > include/linux/user_namespace.h | 8 ++++++++ > kernel/user_namespace.c | 14 ++++++++++++++ > security/commoncap.c | 4 +++- > security/security.c | 10 +++++++++- > security/selinux/hooks.c | 16 +++++++++++++++- > security/smack/smack_lsm.c | 12 ++++++++++-- > 14 files changed, 134 insertions(+), 28 deletions(-) > > -- > To unsubscribe from this list: send the line "unsubscribe linux-security-module" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
