forked from Minki/linux
a867d7349e
Pull userns vfs updates from Eric Biederman:
"This tree contains some very long awaited work on generalizing the
user namespace support for mounting filesystems to include filesystems
with a backing store. The real world target is fuse but the goal is
to update the vfs to allow any filesystem to be supported. This
patchset is based on a lot of code review and testing to approach that
goal.
While looking at what is needed to support the fuse filesystem it
became clear that there were things like xattrs for security modules
that needed special treatment. That the resolution of those concerns
would not be fuse specific. That sorting out these general issues
made most sense at the generic level, where the right people could be
drawn into the conversation, and the issues could be solved for
everyone.
At a high level what this patchset does a couple of simple things:
- Add a user namespace owner (s_user_ns) to struct super_block.
- Teach the vfs to handle filesystem uids and gids not mapping into
to kuids and kgids and being reported as INVALID_UID and
INVALID_GID in vfs data structures.
By assigning a user namespace owner filesystems that are mounted with
only user namespace privilege can be detected. This allows security
modules and the like to know which mounts may not be trusted. This
also allows the set of uids and gids that are communicated to the
filesystem to be capped at the set of kuids and kgids that are in the
owning user namespace of the filesystem.
One of the crazier corner casees this handles is the case of inodes
whose i_uid or i_gid are not mapped into the vfs. Most of the code
simply doesn't care but it is easy to confuse the inode writeback path
so no operation that could cause an inode write-back is permitted for
such inodes (aka only reads are allowed).
This set of changes starts out by cleaning up the code paths involved
in user namespace permirted mounts. Then when things are clean enough
adds code that cleanly sets s_user_ns. Then additional restrictions
are added that are possible now that the filesystem superblock
contains owner information.
These changes should not affect anyone in practice, but there are some
parts of these restrictions that are changes in behavior.
- Andy's restriction on suid executables that does not honor the
suid bit when the path is from another mount namespace (think
/proc/[pid]/fd/) or when the filesystem was mounted by a less
privileged user.
- The replacement of the user namespace implicit setting of MNT_NODEV
with implicitly setting SB_I_NODEV on the filesystem superblock
instead.
Using SB_I_NODEV is a stronger form that happens to make this state
user invisible. The user visibility can be managed but it caused
problems when it was introduced from applications reasonably
expecting mount flags to be what they were set to.
There is a little bit of work remaining before it is safe to support
mounting filesystems with backing store in user namespaces, beyond
what is in this set of changes.
- Verifying the mounter has permission to read/write the block device
during mount.
- Teaching the integrity modules IMA and EVM to handle filesystems
mounted with only user namespace root and to reduce trust in their
security xattrs accordingly.
- Capturing the mounters credentials and using that for permission
checks in d_automount and the like. (Given that overlayfs already
does this, and we need the work in d_automount it make sense to
generalize this case).
Furthermore there are a few changes that are on the wishlist:
- Get all filesystems supporting posix acls using the generic posix
acls so that posix_acl_fix_xattr_from_user and
posix_acl_fix_xattr_to_user may be removed. [Maintainability]
- Reducing the permission checks in places such as remount to allow
the superblock owner to perform them.
- Allowing the superblock owner to chown files with unmapped uids and
gids to something that is mapped so the files may be treated
normally.
I am not considering even obvious relaxations of permission checks
until it is clear there are no more corner cases that need to be
locked down and handled generically.
Many thanks to Seth Forshee who kept this code alive, and putting up
with me rewriting substantial portions of what he did to handle more
corner cases, and for his diligent testing and reviewing of my
changes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (30 commits)
fs: Call d_automount with the filesystems creds
fs: Update i_[ug]id_(read|write) to translate relative to s_user_ns
evm: Translate user/group ids relative to s_user_ns when computing HMAC
dquot: For now explicitly don't support filesystems outside of init_user_ns
quota: Handle quota data stored in s_user_ns in quota_setxquota
quota: Ensure qids map to the filesystem
vfs: Don't create inodes with a uid or gid unknown to the vfs
vfs: Don't modify inodes with a uid or gid unknown to the vfs
cred: Reject inodes with invalid ids in set_create_file_as()
fs: Check for invalid i_uid in may_follow_link()
vfs: Verify acls are valid within superblock's s_user_ns.
userns: Handle -1 in k[ug]id_has_mapping when !CONFIG_USER_NS
fs: Refuse uid/gid changes which don't map into s_user_ns
selinux: Add support for unprivileged mounts from user namespaces
Smack: Handle labels consistently in untrusted mounts
Smack: Add support for unprivileged mounts from user namespaces
fs: Treat foreign mounts as nosuid
fs: Limit file caps to the user namespace of the super block
userns: Remove the now unnecessary FS_USERNS_DEV_MOUNT flag
userns: Remove implicit MNT_NODEV fragility.
...
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| include/linux | ||
| lnet | ||
| lustre | ||
| Kconfig | ||
| Makefile | ||
| README.txt | ||
| sysfs-fs-lustre | ||
| TODO | ||
Lustre Parallel Filesystem Client ================================= The Lustre file system is an open-source, parallel file system that supports many requirements of leadership class HPC simulation environments. Born from from a research project at Carnegie Mellon University, the Lustre file system is a widely-used option in HPC. The Lustre file system provides a POSIX compliant file system interface, can scale to thousands of clients, petabytes of storage and hundreds of gigabytes per second of I/O bandwidth. Unlike shared disk storage cluster filesystems (e.g. OCFS2, GFS, GPFS), Lustre has independent Metadata and Data servers that clients can access in parallel to maximize performance. In order to use Lustre client you will need to download the "lustre-client" package that contains the userspace tools from http://lustre.org/download/ You will need to install and configure your Lustre servers separately. Mount Syntax ============ After you installed the lustre-client tools including mount.lustre binary you can mount your Lustre filesystem with: mount -t lustre mgs:/fsname mnt where mgs is the host name or ip address of your Lustre MGS(management service) fsname is the name of the filesystem you would like to mount. Mount Options ============= noflock Disable posix file locking (Applications trying to use the functionality will get ENOSYS) localflock Enable local flock support, using only client-local flock (faster, for applications that require flock but do not run on multiple nodes). flock Enable cluster-global posix file locking coherent across all client nodes. user_xattr, nouser_xattr Support "user." extended attributes (or not) user_fid2path, nouser_fid2path Enable FID to path translation by regular users (or not) checksum, nochecksum Verify data consistency on the wire and in memory as it passes between the layers (or not). lruresize, nolruresize Allow lock LRU to be controlled by memory pressure on the server (or only 100 (default, controlled by lru_size proc parameter) locks per CPU per server on this client). lazystatfs, nolazystatfs Do not block in statfs() if some of the servers are down. 32bitapi Shrink inode numbers to fit into 32 bits. This is necessary if you plan to reexport Lustre filesystem from this client via NFSv4. verbose, noverbose Enable mount/umount console messages (or not) More Information ================ You can get more information at the Lustre website: http://wiki.lustre.org/ Source for the userspace tools and out-of-tree client and server code is available at: http://git.hpdd.intel.com/fs/lustre-release.git Latest binary packages: http://lustre.org/download/