Commit Graph

58 Commits

Author SHA1 Message Date
Christian Brauner 831be973aa
xattr: remove unused argument
his helpers is really just used to check for user.* xattr support so
don't make it pointlessly generic.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-06 09:57:11 +01:00
Christian Brauner 2db8a94804
xattr: add listxattr helper
Add a tiny helper to determine whether an xattr handler given a specific
dentry supports listing the requested xattr. We will use this helper in
various filesystems in later commits.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-06 09:57:11 +01:00
Christian Brauner f2620f166e
xattr: simplify listxattr helpers
The generic_listxattr() and simple_xattr_list() helpers list xattrs and
contain duplicated code. Add two helpers that both generic_listxattr()
and simple_xattr_list() can use.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-06 09:57:07 +01:00
Christian Brauner 39f60c1cce
fs: port xattr to mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:28 +01:00
Christian Brauner 4609e1f18e
fs: port ->permission() to pass mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:28 +01:00
Linus Torvalds 02bf43c7b7 fs.xattr.simple.rework.rbtree.rwlock.v6.2
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Merge tag 'fs.xattr.simple.rework.rbtree.rwlock.v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping

Pull simple-xattr updates from Christian Brauner:
 "This ports the simple xattr infrastucture to rely on a simple rbtree
  protected by a read-write lock instead of a linked list protected by a
  spinlock.

  A while ago we received reports about scaling issues for filesystems
  using the simple xattr infrastructure that also support setting a
  larger number of xattrs. Specifically, cgroups and tmpfs.

  Both cgroupfs and tmpfs can be mounted by unprivileged users in
  unprivileged containers and root in an unprivileged container can set
  an unrestricted number of security.* xattrs and privileged users can
  also set unlimited trusted.* xattrs. A few more words on further that
  below. Other xattrs such as user.* are restricted for kernfs-based
  instances to a fairly limited number.

  As there are apparently users that have a fairly large number of
  xattrs we should scale a bit better. Using a simple linked list
  protected by a spinlock used for set, get, and list operations doesn't
  scale well if users use a lot of xattrs even if it's not a crazy
  number.

  Let's switch to a simple rbtree protected by a rwlock. It scales way
  better and gets rid of the perf issues some people reported. We
  originally had fancier solutions even using an rcu+seqlock protected
  rbtree but we had concerns about being to clever and also that
  deletion from an rbtree with rcu+seqlock isn't entirely safe.

  The rbtree plus rwlock is perfectly fine. By far the most common
  operation is getting an xattr. While setting an xattr is not and
  should be comparatively rare. And listxattr() often only happens when
  copying xattrs between files or together with the contents to a new
  file.

  Holding a lock across listxattr() is unproblematic because it doesn't
  list the values of xattrs. It can only be used to list the names of
  all xattrs set on a file. And the number of xattr names that can be
  listed with listxattr() is limited to XATTR_LIST_MAX aka 65536 bytes.
  If a larger buffer is passed then vfs_listxattr() caps it to
  XATTR_LIST_MAX and if more xattr names are found it will return
  -E2BIG. In short, the maximum amount of memory that can be retrieved
  via listxattr() is limited and thus listxattr() bounded.

  Of course, the API is broken as documented on xattr(7) already. While
  I have no idea how the xattr api ended up in this state we should
  probably try to come up with something here at some point. An iterator
  pattern similar to readdir() as an alternative to listxattr() or
  something else.

  Right now it is extremly strange that users can set millions of xattrs
  but then can't use listxattr() to know which xattrs are actually set.
  And it's really trivial to do:

	for i in {1..1000000}; do setfattr -n security.$i -v $i ./file1; done

  And around 5000 xattrs it's impossible to use listxattr() to figure
  out which xattrs are actually set. So I have suggested that we try to
  limit the number of xattrs for simple xattrs at least. But that's a
  future patch and I don't consider it very urgent.

  A bonus of this port to rbtree+rwlock is that we shrink the memory
  consumption for users of the simple xattr infrastructure.

  This also adds kernel documentation to all the functions"

* tag 'fs.xattr.simple.rework.rbtree.rwlock.v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping:
  xattr: use rbtree for simple_xattrs
2022-12-13 10:08:36 -08:00
Linus Torvalds c76ff350bd lsm/stable-6.2 PR 20221212
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Merge tag 'lsm-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

Pull lsm updates from Paul Moore:

 - Improve the error handling in the device cgroup such that memory
   allocation failures when updating the access policy do not
   potentially alter the policy.

 - Some minor fixes to reiserfs to ensure that it properly releases
   LSM-related xattr values.

 - Update the security_socket_getpeersec_stream() LSM hook to take
   sockptr_t values.

   Previously the net/BPF folks updated the getsockopt code in the
   network stack to leverage the sockptr_t type to make it easier to
   pass both kernel and __user pointers, but unfortunately when they did
   so they didn't convert the LSM hook.

   While there was/is no immediate risk by not converting the LSM hook,
   it seems like this is a mistake waiting to happen so this patch
   proactively does the LSM hook conversion.

 - Convert vfs_getxattr_alloc() to return an int instead of a ssize_t
   and cleanup the callers. Internally the function was never going to
   return anything larger than an int and the callers were doing some
   very odd things casting the return value; this patch fixes all that
   and helps bring a bit of sanity to vfs_getxattr_alloc() and its
   callers.

 - More verbose, and helpful, LSM debug output when the system is booted
   with "lsm.debug" on the command line. There are examples in the
   commit description, but the quick summary is that this patch provides
   better information about which LSMs are enabled and the ordering in
   which they are processed.

 - General comment and kernel-doc fixes and cleanups.

* tag 'lsm-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  lsm: Fix description of fs_context_parse_param
  lsm: Add/fix return values in lsm_hooks.h and fix formatting
  lsm: Clarify documentation of vm_enough_memory hook
  reiserfs: Add missing calls to reiserfs_security_free()
  lsm,fs: fix vfs_getxattr_alloc() return type and caller error paths
  device_cgroup: Roll back to original exceptions after copy failure
  LSM: Better reporting of actual LSMs at boot
  lsm: make security_socket_getpeersec_stream() sockptr_t safe
  audit: Fix some kernel-doc warnings
  lsm: remove obsoleted comments for security hooks
  fs: edit a comment made in bad taste
2022-12-13 09:47:48 -08:00
Paul Moore f6fbd8cbf3 lsm,fs: fix vfs_getxattr_alloc() return type and caller error paths
The vfs_getxattr_alloc() function currently returns a ssize_t value
despite the fact that it only uses int values internally for return
values.  Fix this by converting vfs_getxattr_alloc() to return an
int type and adjust the callers as necessary.  As part of these
caller modifications, some of the callers are fixed to properly free
the xattr value buffer on both success and failure to ensure that
memory is not leaked in the failure case.

Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-11-18 17:07:03 -05:00
Christian Brauner 3b4c7bc017
xattr: use rbtree for simple_xattrs
A while ago Vasily reported that it is possible to set a large number of
xattrs on inodes of filesystems that make use of the simple xattr
infrastructure. This includes all kernfs-based filesystems that support
xattrs (e.g., cgroupfs and tmpfs). Both cgroupfs and tmpfs can be
mounted by unprivileged users in unprivileged containers and root in an
unprivileged container can set an unrestricted number of security.*
xattrs and privileged users can also set unlimited trusted.* xattrs. As
there are apparently users that have a fairly large number of xattrs we
should scale a bit better. Other xattrs such as user.* are restricted
for kernfs-based instances to a fairly limited number.

Using a simple linked list protected by a spinlock used for set, get,
and list operations doesn't scale well if users use a lot of xattrs even
if it's not a crazy number. There's no need to bring in the big guns
like rhashtables or rw semaphores for this. An rbtree with a rwlock, or
limited rcu semanics and seqlock is enough.

It scales within the constraints we are working in. By far the most
common operation is getting an xattr. Setting xattrs should be a
moderately rare operation. And listxattr() often only happens when
copying xattrs between files or together with the contents to a new
file. Holding a lock across listxattr() is unproblematic because it
doesn't list the values of xattrs. It can only be used to list the names
of all xattrs set on a file. And the number of xattr names that can be
listed with listxattr() is limited to XATTR_LIST_MAX aka 65536 bytes. If
a larger buffer is passed then vfs_listxattr() caps it to XATTR_LIST_MAX
and if more xattr names are found it will return -E2BIG. In short, the
maximum amount of memory that can be retrieved via listxattr() is
limited.

Of course, the API is broken as documented on xattr(7) already. In the
future we might want to address this but for now this is the world we
live in and have lived for a long time. But it does indeed mean that
once an application goes over XATTR_LIST_MAX limit of xattrs set on an
inode it isn't possible to copy the file and include its xattrs in the
copy unless the caller knows all xattrs or limits the copy of the xattrs
to important ones it knows by name (At least for tmpfs, and kernfs-based
filesystems. Other filesystems might provide ways of achieving this.).

Bonus of this port to rbtree+rwlock is that we shrink the memory
consumption for users of the simple xattr infrastructure.

Also add proper kernel documentation to all the functions.
A big thanks to Paul for his comments.

Cc: Vasily Averin <vvs@openvz.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2022-11-12 10:49:26 +01:00
Christian Brauner 31acceb975
ovl: use posix acl api
Now that posix acls have a proper api us it to copy them.

All filesystems that can serve as lower or upper layers for overlayfs
have gained support for the new posix acl api in previous patches.
So switch all internal overlayfs codepaths for copying posix acls to the
new posix acl api.

Acked-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2022-10-20 10:13:31 +02:00
Christian Brauner 6344e66970
xattr: constify value argument in vfs_setxattr()
Now that we don't perform translations directly in vfs_setxattr()
anymore we can constify the @value argument in vfs_setxattr(). This also
allows us to remove the hack to cast from a const in ovl_do_setxattr().

Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
2022-08-31 16:38:07 +02:00
Christian Brauner 0c5fd887d2
acl: move idmapped mount fixup into vfs_{g,s}etxattr()
This cycle we added support for mounting overlayfs on top of idmapped mounts.
Recently I've started looking into potential corner cases when trying to add
additional tests and I noticed that reporting for POSIX ACLs is currently wrong
when using idmapped layers with overlayfs mounted on top of it.

I'm going to give a rather detailed explanation to both the origin of the
problem and the solution.

Let's assume the user creates the following directory layout and they have a
rootfs /var/lib/lxc/c1/rootfs. The files in this rootfs are owned as you would
expect files on your host system to be owned. For example, ~/.bashrc for your
regular user would be owned by 1000:1000 and /root/.bashrc would be owned by
0:0. IOW, this is just regular boring filesystem tree on an ext4 or xfs
filesystem.

The user chooses to set POSIX ACLs using the setfacl binary granting the user
with uid 4 read, write, and execute permissions for their .bashrc file:

        setfacl -m u:4:rwx /var/lib/lxc/c2/rootfs/home/ubuntu/.bashrc

Now they to expose the whole rootfs to a container using an idmapped mount. So
they first create:

        mkdir -pv /vol/contpool/{ctrover,merge,lowermap,overmap}
        mkdir -pv /vol/contpool/ctrover/{over,work}
        chown 10000000:10000000 /vol/contpool/ctrover/{over,work}

The user now creates an idmapped mount for the rootfs:

        mount-idmapped/mount-idmapped --map-mount=b:0:10000000:65536 \
                                      /var/lib/lxc/c2/rootfs \
                                      /vol/contpool/lowermap

This for example makes it so that /var/lib/lxc/c2/rootfs/home/ubuntu/.bashrc
which is owned by uid and gid 1000 as being owned by uid and gid 10001000 at
/vol/contpool/lowermap/home/ubuntu/.bashrc.

Assume the user wants to expose these idmapped mounts through an overlayfs
mount to a container.

       mount -t overlay overlay                      \
             -o lowerdir=/vol/contpool/lowermap,     \
                upperdir=/vol/contpool/overmap/over, \
                workdir=/vol/contpool/overmap/work   \
             /vol/contpool/merge

The user can do this in two ways:

(1) Mount overlayfs in the initial user namespace and expose it to the
    container.
(2) Mount overlayfs on top of the idmapped mounts inside of the container's
    user namespace.

Let's assume the user chooses the (1) option and mounts overlayfs on the host
and then changes into a container which uses the idmapping 0:10000000:65536
which is the same used for the two idmapped mounts.

Now the user tries to retrieve the POSIX ACLs using the getfacl command

        getfacl -n /vol/contpool/lowermap/home/ubuntu/.bashrc

and to their surprise they see:

        # file: vol/contpool/merge/home/ubuntu/.bashrc
        # owner: 1000
        # group: 1000
        user::rw-
        user:4294967295:rwx
        group::r--
        mask::rwx
        other::r--

indicating the the uid wasn't correctly translated according to the idmapped
mount. The problem is how we currently translate POSIX ACLs. Let's inspect the
callchain in this example:

        idmapped mount /vol/contpool/merge:      0:10000000:65536
        caller's idmapping:                      0:10000000:65536
        overlayfs idmapping (ofs->creator_cred): 0:0:4k /* initial idmapping */

        sys_getxattr()
        -> path_getxattr()
           -> getxattr()
              -> do_getxattr()
                  |> vfs_getxattr()
                  |  -> __vfs_getxattr()
                  |     -> handler->get == ovl_posix_acl_xattr_get()
                  |        -> ovl_xattr_get()
                  |           -> vfs_getxattr()
                  |              -> __vfs_getxattr()
                  |                 -> handler->get() /* lower filesystem callback */
                  |> posix_acl_fix_xattr_to_user()
                     {
                              4 = make_kuid(&init_user_ns, 4);
                              4 = mapped_kuid_fs(&init_user_ns /* no idmapped mount */, 4);
                              /* FAILURE */
                             -1 = from_kuid(0:10000000:65536 /* caller's idmapping */, 4);
                     }

If the user chooses to use option (2) and mounts overlayfs on top of idmapped
mounts inside the container things don't look that much better:

        idmapped mount /vol/contpool/merge:      0:10000000:65536
        caller's idmapping:                      0:10000000:65536
        overlayfs idmapping (ofs->creator_cred): 0:10000000:65536

        sys_getxattr()
        -> path_getxattr()
           -> getxattr()
              -> do_getxattr()
                  |> vfs_getxattr()
                  |  -> __vfs_getxattr()
                  |     -> handler->get == ovl_posix_acl_xattr_get()
                  |        -> ovl_xattr_get()
                  |           -> vfs_getxattr()
                  |              -> __vfs_getxattr()
                  |                 -> handler->get() /* lower filesystem callback */
                  |> posix_acl_fix_xattr_to_user()
                     {
                              4 = make_kuid(&init_user_ns, 4);
                              4 = mapped_kuid_fs(&init_user_ns, 4);
                              /* FAILURE */
                             -1 = from_kuid(0:10000000:65536 /* caller's idmapping */, 4);
                     }

As is easily seen the problem arises because the idmapping of the lower mount
isn't taken into account as all of this happens in do_gexattr(). But
do_getxattr() is always called on an overlayfs mount and inode and thus cannot
possible take the idmapping of the lower layers into account.

This problem is similar for fscaps but there the translation happens as part of
vfs_getxattr() already. Let's walk through an fscaps overlayfs callchain:

        setcap 'cap_net_raw+ep' /var/lib/lxc/c2/rootfs/home/ubuntu/.bashrc

The expected outcome here is that we'll receive the cap_net_raw capability as
we are able to map the uid associated with the fscap to 0 within our container.
IOW, we want to see 0 as the result of the idmapping translations.

If the user chooses option (1) we get the following callchain for fscaps:

        idmapped mount /vol/contpool/merge:      0:10000000:65536
        caller's idmapping:                      0:10000000:65536
        overlayfs idmapping (ofs->creator_cred): 0:0:4k /* initial idmapping */

        sys_getxattr()
        -> path_getxattr()
           -> getxattr()
              -> do_getxattr()
                   -> vfs_getxattr()
                      -> xattr_getsecurity()
                         -> security_inode_getsecurity()                                       ________________________________
                            -> cap_inode_getsecurity()                                         |                              |
                               {                                                               V                              |
                                        10000000 = make_kuid(0:0:4k /* overlayfs idmapping */, 10000000);                     |
                                        10000000 = mapped_kuid_fs(0:0:4k /* no idmapped mount */, 10000000);                  |
                                               /* Expected result is 0 and thus that we own the fscap. */                     |
                                               0 = from_kuid(0:10000000:65536 /* caller's idmapping */, 10000000);            |
                               }                                                                                              |
                               -> vfs_getxattr_alloc()                                                                        |
                                  -> handler->get == ovl_other_xattr_get()                                                    |
                                     -> vfs_getxattr()                                                                        |
                                        -> xattr_getsecurity()                                                                |
                                           -> security_inode_getsecurity()                                                    |
                                              -> cap_inode_getsecurity()                                                      |
                                                 {                                                                            |
                                                                0 = make_kuid(0:0:4k /* lower s_user_ns */, 0);               |
                                                         10000000 = mapped_kuid_fs(0:10000000:65536 /* idmapped mount */, 0); |
                                                         10000000 = from_kuid(0:0:4k /* overlayfs idmapping */, 10000000);    |
                                                         |____________________________________________________________________|
                                                 }
                                                 -> vfs_getxattr_alloc()
                                                    -> handler->get == /* lower filesystem callback */

And if the user chooses option (2) we get:

        idmapped mount /vol/contpool/merge:      0:10000000:65536
        caller's idmapping:                      0:10000000:65536
        overlayfs idmapping (ofs->creator_cred): 0:10000000:65536

        sys_getxattr()
        -> path_getxattr()
           -> getxattr()
              -> do_getxattr()
                   -> vfs_getxattr()
                      -> xattr_getsecurity()
                         -> security_inode_getsecurity()                                                _______________________________
                            -> cap_inode_getsecurity()                                                  |                             |
                               {                                                                        V                             |
                                       10000000 = make_kuid(0:10000000:65536 /* overlayfs idmapping */, 0);                           |
                                       10000000 = mapped_kuid_fs(0:0:4k /* no idmapped mount */, 10000000);                           |
                                               /* Expected result is 0 and thus that we own the fscap. */                             |
                                              0 = from_kuid(0:10000000:65536 /* caller's idmapping */, 10000000);                     |
                               }                                                                                                      |
                               -> vfs_getxattr_alloc()                                                                                |
                                  -> handler->get == ovl_other_xattr_get()                                                            |
                                    |-> vfs_getxattr()                                                                                |
                                        -> xattr_getsecurity()                                                                        |
                                           -> security_inode_getsecurity()                                                            |
                                              -> cap_inode_getsecurity()                                                              |
                                                 {                                                                                    |
                                                                 0 = make_kuid(0:0:4k /* lower s_user_ns */, 0);                      |
                                                          10000000 = mapped_kuid_fs(0:10000000:65536 /* idmapped mount */, 0);        |
                                                                 0 = from_kuid(0:10000000:65536 /* overlayfs idmapping */, 10000000); |
                                                                 |____________________________________________________________________|
                                                 }
                                                 -> vfs_getxattr_alloc()
                                                    -> handler->get == /* lower filesystem callback */

We can see how the translation happens correctly in those cases as the
conversion happens within the vfs_getxattr() helper.

For POSIX ACLs we need to do something similar. However, in contrast to fscaps
we cannot apply the fix directly to the kernel internal posix acl data
structure as this would alter the cached values and would also require a rework
of how we currently deal with POSIX ACLs in general which almost never take the
filesystem idmapping into account (the noteable exception being FUSE but even
there the implementation is special) and instead retrieve the raw values based
on the initial idmapping.

The correct values are then generated right before returning to userspace. The
fix for this is to move taking the mount's idmapping into account directly in
vfs_getxattr() instead of having it be part of posix_acl_fix_xattr_to_user().

To this end we split out two small and unexported helpers
posix_acl_getxattr_idmapped_mnt() and posix_acl_setxattr_idmapped_mnt(). The
former to be called in vfs_getxattr() and the latter to be called in
vfs_setxattr().

Let's go back to the original example. Assume the user chose option (1) and
mounted overlayfs on top of idmapped mounts on the host:

        idmapped mount /vol/contpool/merge:      0:10000000:65536
        caller's idmapping:                      0:10000000:65536
        overlayfs idmapping (ofs->creator_cred): 0:0:4k /* initial idmapping */

        sys_getxattr()
        -> path_getxattr()
           -> getxattr()
              -> do_getxattr()
                  |> vfs_getxattr()
                  |  |> __vfs_getxattr()
                  |  |  -> handler->get == ovl_posix_acl_xattr_get()
                  |  |     -> ovl_xattr_get()
                  |  |        -> vfs_getxattr()
                  |  |           |> __vfs_getxattr()
                  |  |           |  -> handler->get() /* lower filesystem callback */
                  |  |           |> posix_acl_getxattr_idmapped_mnt()
                  |  |              {
                  |  |                              4 = make_kuid(&init_user_ns, 4);
                  |  |                       10000004 = mapped_kuid_fs(0:10000000:65536 /* lower idmapped mount */, 4);
                  |  |                       10000004 = from_kuid(&init_user_ns, 10000004);
                  |  |                       |_______________________
                  |  |              }                               |
                  |  |                                              |
                  |  |> posix_acl_getxattr_idmapped_mnt()           |
                  |     {                                           |
                  |                                                 V
                  |             10000004 = make_kuid(&init_user_ns, 10000004);
                  |             10000004 = mapped_kuid_fs(&init_user_ns /* no idmapped mount */, 10000004);
                  |             10000004 = from_kuid(&init_user_ns, 10000004);
                  |     }       |_________________________________________________
                  |                                                              |
                  |                                                              |
                  |> posix_acl_fix_xattr_to_user()                               |
                     {                                                           V
                                 10000004 = make_kuid(0:0:4k /* init_user_ns */, 10000004);
                                        /* SUCCESS */
                                        4 = from_kuid(0:10000000:65536 /* caller's idmapping */, 10000004);
                     }

And similarly if the user chooses option (1) and mounted overayfs on top of
idmapped mounts inside the container:

        idmapped mount /vol/contpool/merge:      0:10000000:65536
        caller's idmapping:                      0:10000000:65536
        overlayfs idmapping (ofs->creator_cred): 0:10000000:65536

        sys_getxattr()
        -> path_getxattr()
           -> getxattr()
              -> do_getxattr()
                  |> vfs_getxattr()
                  |  |> __vfs_getxattr()
                  |  |  -> handler->get == ovl_posix_acl_xattr_get()
                  |  |     -> ovl_xattr_get()
                  |  |        -> vfs_getxattr()
                  |  |           |> __vfs_getxattr()
                  |  |           |  -> handler->get() /* lower filesystem callback */
                  |  |           |> posix_acl_getxattr_idmapped_mnt()
                  |  |              {
                  |  |                              4 = make_kuid(&init_user_ns, 4);
                  |  |                       10000004 = mapped_kuid_fs(0:10000000:65536 /* lower idmapped mount */, 4);
                  |  |                       10000004 = from_kuid(&init_user_ns, 10000004);
                  |  |                       |_______________________
                  |  |              }                               |
                  |  |                                              |
                  |  |> posix_acl_getxattr_idmapped_mnt()           |
                  |     {                                           V
                  |             10000004 = make_kuid(&init_user_ns, 10000004);
                  |             10000004 = mapped_kuid_fs(&init_user_ns /* no idmapped mount */, 10000004);
                  |             10000004 = from_kuid(0(&init_user_ns, 10000004);
                  |             |_________________________________________________
                  |     }                                                        |
                  |                                                              |
                  |> posix_acl_fix_xattr_to_user()                               |
                     {                                                           V
                                 10000004 = make_kuid(0:0:4k /* init_user_ns */, 10000004);
                                        /* SUCCESS */
                                        4 = from_kuid(0:10000000:65536 /* caller's idmappings */, 10000004);
                     }

The last remaining problem we need to fix here is ovl_get_acl(). During
ovl_permission() overlayfs will call:

        ovl_permission()
        -> generic_permission()
           -> acl_permission_check()
              -> check_acl()
                 -> get_acl()
                    -> inode->i_op->get_acl() == ovl_get_acl()
                        > get_acl() /* on the underlying filesystem)
                          ->inode->i_op->get_acl() == /*lower filesystem callback */
                 -> posix_acl_permission()

passing through the get_acl request to the underlying filesystem. This will
retrieve the acls stored in the lower filesystem without taking the idmapping
of the underlying mount into account as this would mean altering the cached
values for the lower filesystem. So we block using ACLs for now until we
decided on a nice way to fix this. Note this limitation both in the
documentation and in the code.

The most straightforward solution would be to have ovl_get_acl() simply
duplicate the ACLs, update the values according to the idmapped mount and
return it to acl_permission_check() so it can be used in posix_acl_permission()
forgetting them afterwards. This is a bit heavy handed but fairly
straightforward otherwise.

Link: https://github.com/brauner/mount-idmapped/issues/9
Link: https://lore.kernel.org/r/20220708090134.385160-2-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: linux-unionfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2022-07-15 22:08:59 +02:00
Tycho Andersen c7c7a1a18a
xattr: handle idmapped mounts
When interacting with extended attributes the vfs verifies that the
caller is privileged over the inode with which the extended attribute is
associated. For posix access and posix default extended attributes a uid
or gid can be stored on-disk. Let the functions handle posix extended
attributes on idmapped mounts. If the inode is accessed through an
idmapped mount we need to map it according to the mount's user
namespace. Afterwards the checks are identical to non-idmapped mounts.
This has no effect for e.g. security xattrs since they don't store uids
or gids and don't perform permission checks on them like posix acls do.

Link: https://lore.kernel.org/r/20210121131959.646623-10-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Tycho Andersen <tycho@tycho.pizza>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-24 14:27:17 +01:00
Christian Brauner e65ce2a50c
acl: handle idmapped mounts
The posix acl permission checking helpers determine whether a caller is
privileged over an inode according to the acls associated with the
inode. Add helpers that make it possible to handle acls on idmapped
mounts.

The vfs and the filesystems targeted by this first iteration make use of
posix_acl_fix_xattr_from_user() and posix_acl_fix_xattr_to_user() to
translate basic posix access and default permissions such as the
ACL_USER and ACL_GROUP type according to the initial user namespace (or
the superblock's user namespace) to and from the caller's current user
namespace. Adapt these two helpers to handle idmapped mounts whereby we
either map from or into the mount's user namespace depending on in which
direction we're translating.
Similarly, cap_convert_nscap() is used by the vfs to translate user
namespace and non-user namespace aware filesystem capabilities from the
superblock's user namespace to the caller's user namespace. Enable it to
handle idmapped mounts by accounting for the mount's user namespace.

In addition the fileystems targeted in the first iteration of this patch
series make use of the posix_acl_chmod() and, posix_acl_update_mode()
helpers. Both helpers perform permission checks on the target inode. Let
them handle idmapped mounts. These two helpers are called when posix
acls are set by the respective filesystems to handle this case we extend
the ->set() method to take an additional user namespace argument to pass
the mount's user namespace down.

Link: https://lore.kernel.org/r/20210121131959.646623-9-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-24 14:27:17 +01:00
Linus Torvalds 7a6b60441f Highlights:
- Support for user extended attributes on NFS (RFC 8276)
 - Further reduce unnecessary NFSv4 delegation recalls
 
 Notable fixes:
 
 - Fix recent krb5p regression
 - Address a few resource leaks and a rare NULL dereference
 
 Other:
 
 - De-duplicate RPC/RDMA error handling and other utility functions
 - Replace storage and display of kernel memory addresses by tracepoints
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Merge tag 'nfsd-5.9' of git://git.linux-nfs.org/projects/cel/cel-2.6

Pull NFS server updates from Chuck Lever:
 "Highlights:
   - Support for user extended attributes on NFS (RFC 8276)
   - Further reduce unnecessary NFSv4 delegation recalls

  Notable fixes:
   - Fix recent krb5p regression
   - Address a few resource leaks and a rare NULL dereference

  Other:
   - De-duplicate RPC/RDMA error handling and other utility functions
   - Replace storage and display of kernel memory addresses by tracepoints"

* tag 'nfsd-5.9' of git://git.linux-nfs.org/projects/cel/cel-2.6: (38 commits)
  svcrdma: CM event handler clean up
  svcrdma: Remove transport reference counting
  svcrdma: Fix another Receive buffer leak
  SUNRPC: Refresh the show_rqstp_flags() macro
  nfsd: netns.h: delete a duplicated word
  SUNRPC: Fix ("SUNRPC: Add "@len" parameter to gss_unwrap()")
  nfsd: avoid a NULL dereference in __cld_pipe_upcall()
  nfsd4: a client's own opens needn't prevent delegations
  nfsd: Use seq_putc() in two functions
  svcrdma: Display chunk completion ID when posting a rw_ctxt
  svcrdma: Record send_ctxt completion ID in trace_svcrdma_post_send()
  svcrdma: Introduce Send completion IDs
  svcrdma: Record Receive completion ID in svc_rdma_decode_rqst
  svcrdma: Introduce Receive completion IDs
  svcrdma: Introduce infrastructure to support completion IDs
  svcrdma: Add common XDR encoders for RDMA and Read segments
  svcrdma: Add common XDR decoders for RDMA and Read segments
  SUNRPC: Add helpers for decoding list discriminators symbolically
  svcrdma: Remove declarations for functions long removed
  svcrdma: Clean up trace_svcrdma_send_failed() tracepoint
  ...
2020-08-09 13:58:04 -07:00
Chengguang Xu 3bef735ad7 vfs/xattr: mm/shmem: kernfs: release simple xattr entry in a right way
After commit fdc85222d5 ("kernfs: kvmalloc xattr value instead of
kmalloc"), simple xattr entry is allocated with kvmalloc() instead of
kmalloc(), so we should release it with kvfree() instead of kfree().

Fixes: fdc85222d5 ("kernfs: kvmalloc xattr value instead of kmalloc")
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Daniel Xu <dxu@dxuuu.xyz>
Cc: Chris Down <chris@chrisdown.name>
Cc: Andreas Dilger <adilger@dilger.ca>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>	[5.7]
Link: http://lkml.kernel.org/r/20200704051608.15043-1-cgxu519@mykernel.net
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-07-24 12:42:41 -07:00
Frank van der Linden cab8d289c5 xattr: add a function to check if a namespace is supported
Add a function that checks is an extended attribute namespace is
supported for an inode, meaning that a handler must be present
for either the whole namespace, or at least one synthetic
xattr in the namespace.

To be used by the nfs server code when being queried for extended
attributes support.

Cc: linux-fsdevel@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-13 17:27:03 -04:00
Frank van der Linden 08b5d5014a xattr: break delegations in {set,remove}xattr
set/removexattr on an exported filesystem should break NFS delegations.
This is true in general, but also for the upcoming support for
RFC 8726 (NFSv4 extended attribute support). Make sure that they do.

Additionally, they need to grow a _locked variant, since callers might
call this with i_rwsem held (like the NFS server code).

Cc: stable@vger.kernel.org # v4.9+
Cc: linux-fsdevel@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-13 17:27:03 -04:00
Gustavo A. R. Silva 43951585e1 xattr.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Daniel Xu a46a22955b kernfs: Add removed_size out param for simple_xattr_set
This helps set up size accounting in the next commit. Without this out
param, it's difficult to find out the removed xattr size without taking
a lock for longer and walking the xattr linked list twice.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Acked-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
2020-03-16 15:53:47 -04:00
Al Viro 2220c5b0a7 make xattr_getsecurity() static
many years overdue...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-05-14 09:51:34 -04:00
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Andreas Gruenbacher fd50ecaddf vfs: Remove {get,set,remove}xattr inode operations
These inode operations are no longer used; remove them.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-10-07 21:48:36 -04:00
Andreas Gruenbacher 5d6c31910b xattr: Add __vfs_{get,set,remove}xattr helpers
Right now, various places in the kernel check for the existence of
getxattr, setxattr, and removexattr inode operations and directly call
those operations.  Switch to helper functions and test for the IOP_XATTR
flag instead.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Acked-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-10-07 20:10:44 -04:00
Al Viro 3767e255b3 switch ->setxattr() to passing dentry and inode separately
smack ->d_instantiate() uses ->setxattr(), so to be able to call it before
we'd hashed the new dentry and attached it to inode, we need ->setxattr()
instances getting the inode as an explicit argument rather than obtaining
it from dentry.

Similar change for ->getxattr() had been done in commit ce23e64.  Unlike
->getxattr() (which is used by both selinux and smack instances of
->d_instantiate()) ->setxattr() is used only by smack one and unfortunately
it got missed back then.

Reported-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Tested-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-27 20:09:16 -04:00
Al Viro 5930122683 switch xattr_handler->set() to passing dentry and inode separately
preparation for similar switch in ->setxattr() (see the next commit for
rationale).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-27 15:39:43 -04:00
Al Viro ce23e64013 ->getxattr(): pass dentry and inode as separate arguments
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-04-11 00:48:00 -04:00
Al Viro b296821a7c xattr_handler: pass dentry and inode as separate arguments of ->get()
... and do not assume they are already attached to each other

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-04-10 20:48:24 -04:00
Andreas Gruenbacher 764a5c6b1f xattr handlers: Simplify list operation
Change the list operation to only return whether or not an attribute
should be listed.  Copying the attribute names into the buffer is moved
to the callers.

Since the result only depends on the dentry and not on the attribute
name, we do not pass the attribute name to list operations.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-13 19:46:12 -05:00
Andreas Gruenbacher 786534b92f tmpfs: listxattr should include POSIX ACL xattrs
When a file on tmpfs has an ACL or a Default ACL, listxattr should include the
corresponding xattr name.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-06 21:34:15 -05:00
Andreas Gruenbacher aa7c5241c3 tmpfs: Use xattr handler infrastructure
Use the VFS xattr handler infrastructure and get rid of similar code in
the filesystem.  For implementing shmem_xattr_handler_set, we need a
version of simple_xattr_set which removes the attribute when value is
NULL.  Use this to implement kernfs_iop_removexattr as well.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-06 21:34:15 -05:00
Andreas Gruenbacher 98e9cb5711 vfs: Distinguish between full xattr names and proper prefixes
Add an additional "name" field to struct xattr_handler.  When the name
is set, the handler matches attributes with exactly that name.  When the
prefix is set instead, the handler matches attributes with the given
prefix and with a non-empty suffix.

This patch should avoid bugs like the one fixed in commit c361016a in
the future.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-06 21:33:52 -05:00
Andreas Gruenbacher 80602324d5 vfs: Remove vfs_xattr_cmp
This function was only briefly used in security/integrity/evm, between
commits 66dbc325 and 15647eb3.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-06 21:25:16 -05:00
Andreas Gruenbacher e409de992e 9p: xattr simplifications
Now that the xattr handler is passed to the xattr handler operations, we
can use the same get and set operations for the user, trusted, and security
xattr namespaces.  In those namespaces, we can access the full attribute
name by "reattaching" the name prefix the vfs has skipped for us.  Add a
xattr_full_name helper to make this obvious in the code.

For the "system.posix_acl_access" and "system.posix_acl_default"
attributes, handler->prefix is the full attribute name; the suffix is the
empty string.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Cc: v9fs-developer@lists.sourceforge.net
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-11-13 20:34:33 -05:00
Tetsuo Handa 9548906b2b xattr: Constify ->name member of "struct xattr".
Since everybody sets kstrdup()ed constant string to "struct xattr"->name but
nobody modifies "struct xattr"->name , we can omit kstrdup() and its failure
checking by constifying ->name member of "struct xattr".

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Joel Becker <jlbec@evilplan.org> [ocfs2]
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Tested-by: Paul Moore <paul@paul-moore.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2013-07-25 19:30:03 +10:00
David Howells 607ca46e97 UAPI: (Scripted) Disintegrate include/linux
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
2012-10-13 10:46:48 +01:00
Linus Torvalds 88265322c1 Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull security subsystem updates from James Morris:
 "Highlights:

   - Integrity: add local fs integrity verification to detect offline
     attacks
   - Integrity: add digital signature verification
   - Simple stacking of Yama with other LSMs (per LSS discussions)
   - IBM vTPM support on ppc64
   - Add new driver for Infineon I2C TIS TPM
   - Smack: add rule revocation for subject labels"

Fixed conflicts with the user namespace support in kernel/auditsc.c and
security/integrity/ima/ima_policy.c.

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (39 commits)
  Documentation: Update git repository URL for Smack userland tools
  ima: change flags container data type
  Smack: setprocattr memory leak fix
  Smack: implement revoking all rules for a subject label
  Smack: remove task_wait() hook.
  ima: audit log hashes
  ima: generic IMA action flag handling
  ima: rename ima_must_appraise_or_measure
  audit: export audit_log_task_info
  tpm: fix tpm_acpi sparse warning on different address spaces
  samples/seccomp: fix 31 bit build on s390
  ima: digital signature verification support
  ima: add support for different security.ima data types
  ima: add ima_inode_setxattr/removexattr function and calls
  ima: add inode_post_setattr call
  ima: replace iint spinblock with rwlock/read_lock
  ima: allocating iint improvements
  ima: add appraise action keywords and default rules
  ima: integrity appraisal extension
  vfs: move ima_file_free before releasing the file
  ...
2012-10-02 21:38:48 -07:00
Mimi Zohar 2fe5d6def1 ima: integrity appraisal extension
IMA currently maintains an integrity measurement list used to assert the
integrity of the running system to a third party.  The IMA-appraisal
extension adds local integrity validation and enforcement of the
measurement against a "good" value stored as an extended attribute
'security.ima'.  The initial methods for validating 'security.ima' are
hashed based, which provides file data integrity, and digital signature
based, which in addition to providing file data integrity, provides
authenticity.

This patch creates and maintains the 'security.ima' xattr, containing
the file data hash measurement.  Protection of the xattr is provided by
EVM, if enabled and configured.

Based on policy, IMA calls evm_verifyxattr() to verify a file's metadata
integrity and, assuming success, compares the file's current hash value
with the one stored as an extended attribute in 'security.ima'.

Changelov v4:
- changed iint cache flags to hex values

Changelog v3:
- change appraisal default for filesystems without xattr support to fail

Changelog v2:
- fix audit msg 'res' value
- removed unused 'ima_appraise=' values

Changelog v1:
- removed unused iint mutex (Dmitry Kasatkin)
- setattr hook must not reset appraised (Dmitry Kasatkin)
- evm_verifyxattr() now differentiates between no 'security.evm' xattr
  (INTEGRITY_NOLABEL) and no EVM 'protected' xattrs included in the
  'security.evm' (INTEGRITY_NOXATTRS).
- replace hash_status with ima_status (Dmitry Kasatkin)
- re-initialize slab element ima_status on free (Dmitry Kasatkin)
- include 'security.ima' in EVM if CONFIG_IMA_APPRAISE, not CONFIG_IMA
- merged half "ima: ima_must_appraise_or_measure API change" (Dmitry Kasatkin)
- removed unnecessary error variable in process_measurement() (Dmitry Kasatkin)
- use ima_inode_post_setattr() stub function, if IMA_APPRAISE not configured
  (moved ima_inode_post_setattr() to ima_appraise.c)
- make sure ima_collect_measurement() can read file

Changelog:
- add 'iint' to evm_verifyxattr() call (Dimitry Kasatkin)
- fix the race condition between chmod, which takes the i_mutex and then
  iint->mutex, and ima_file_free() and process_measurement(), which take
  the locks in the reverse order, by eliminating iint->mutex. (Dmitry Kasatkin)
- cleanup of ima_appraise_measurement() (Dmitry Kasatkin)
- changes as a result of the iint not allocated for all regular files, but
  only for those measured/appraised.
- don't try to appraise new/empty files
- expanded ima_appraisal description in ima/Kconfig
- IMA appraise definitions required even if IMA_APPRAISE not enabled
- add return value to ima_must_appraise() stub
- unconditionally set status = INTEGRITY_PASS *after* testing status,
  not before.  (Found by Joe Perches)

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
2012-09-07 14:57:44 -04:00
Aristeu Rozanski 38f3865744 xattr: extract simple_xattr code from tmpfs
Extract in-memory xattr APIs from tmpfs. Will be used by cgroup.

$ size vmlinux.o
   text    data     bss     dec     hex filename
4658782  880729 5195032 10734543         a3cbcf vmlinux.o
$ size vmlinux.o
   text    data     bss     dec     hex filename
4658957  880729 5195032 10734718         a3cc7e vmlinux.o

v7:
- checkpatch warnings fixed
- Implement the changes requested by Hugh Dickins:
	- make simple_xattrs_init and simple_xattrs_free inline
	- get rid of locking and list reinitialization in simple_xattrs_free,
	  they're not needed
v6:
- no changes
v5:
- no changes
v4:
- move simple_xattrs_free() to fs/xattr.c
v3:
- in kmem_xattrs_free(), reinitialize the list
- use simple_xattr_* prefix
- introduce simple_xattr_add() to prevent direct list usage

Original-patch-by: Li Zefan <lizefan@huawei.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Lennart Poettering <lpoetter@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2012-08-24 15:55:33 -07:00
Mimi Zohar bf6d0f5dcd evm: posix acls modify i_mode
The posix xattr acls are 'system' prefixed, which normally would not
affect security.evm.  An interesting side affect of writing posix xattr
acls is their modifying of the i_mode, which is included in security.evm.

This patch updates security.evm when posix xattr acls are written.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-09-14 15:24:51 -04:00
Mimi Zohar 66dbc325af evm: re-release
EVM protects a file's security extended attributes(xattrs) against integrity
attacks.  This patchset provides the framework and an initial method.  The
initial method maintains an HMAC-sha1 value across the security extended
attributes, storing the HMAC value as the extended attribute 'security.evm'.
Other methods of validating the integrity of a file's metadata will be posted
separately (eg. EVM-digital-signatures).

While this patchset does authenticate the security xattrs, and
cryptographically binds them to the inode, coming extensions will bind other
directory and inode metadata for more complete protection.  To help simplify
the review and upstreaming process, each extension will be posted separately
(eg. IMA-appraisal, IMA-appraisal-directory).  For a general overview of the
proposed Linux integrity subsystem, refer to Dave Safford's whitepaper:
http://downloads.sf.net/project/linux-ima/linux-ima/Integrity_overview.pdf.

EVM depends on the Kernel Key Retention System to provide it with a
trusted/encrypted key for the HMAC-sha1 operation. The key is loaded onto the
root's keyring using keyctl.  Until EVM receives notification that the key has
been successfully loaded onto the keyring (echo 1 > <securityfs>/evm), EVM can
not create or validate the 'security.evm' xattr, but returns INTEGRITY_UNKNOWN.
Loading the key and signaling EVM should be done as early as possible. Normally
this is done in the initramfs, which has already been measured as part of the
trusted boot.  For more information on creating and loading existing
trusted/encrypted keys, refer to Documentation/keys-trusted-encrypted.txt.  A
sample dracut patch, which loads the trusted/encrypted key and enables EVM, is
available from http://linux-ima.sourceforge.net/#EVM.

Based on the LSMs enabled, the set of EVM protected security xattrs is defined
at compile.  EVM adds the following three calls to the existing security hooks:
evm_inode_setxattr(), evm_inode_post_setxattr(), and evm_inode_removexattr.  To
initialize and update the 'security.evm' extended attribute, EVM defines three
calls: evm_inode_post_init(), evm_inode_post_setattr() and
evm_inode_post_removexattr() hooks.  To verify the integrity of a security
xattr, EVM exports evm_verifyxattr().

Changelog v7:
- Fixed URL in EVM ABI documentation

Changelog v6: (based on Serge Hallyn's review)
- fix URL in patch description
- remove evm_hmac_size definition
- use SHA1_DIGEST_SIZE (removed both MAX_DIGEST_SIZE and evm_hmac_size)
- moved linux include before other includes
- test for crypto_hash_setkey failure
- fail earlier for invalid key
- clear entire encrypted key, even on failure
- check xattr name length before comparing xattr names

Changelog:
- locking based on i_mutex, remove evm_mutex
- using trusted/encrypted keys for storing the EVM key used in the HMAC-sha1
  operation.
- replaced crypto hash with shash (Dmitry Kasatkin)
- support for additional methods of verifying the security xattrs
  (Dmitry Kasatkin)
- iint not allocated for all regular files, but only for those appraised
- Use cap_sys_admin in lieu of cap_mac_admin
- Use __vfs_setxattr_noperm(), without permission checks, from EVM

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
2011-07-18 12:29:40 -04:00
Mimi Zohar 1601fbad2b xattr: define vfs_getxattr_alloc and vfs_xattr_cmp
vfs_getxattr_alloc() and vfs_xattr_cmp() are two new kernel xattr helper
functions.  vfs_getxattr_alloc() first allocates memory for the requested
xattr and then retrieves it. vfs_xattr_cmp() compares a given value with
the contents of an extended attribute.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
2011-07-18 12:29:39 -04:00
Mimi Zohar 9d8f13ba3f security: new security_inode_init_security API adds function callback
This patch changes the security_inode_init_security API by adding a
filesystem specific callback to write security extended attributes.
This change is in preparation for supporting the initialization of
multiple LSM xattrs and the EVM xattr.  Initially the callback function
walks an array of xattrs, writing each xattr separately, but could be
optimized to write multiple xattrs at once.

For existing security_inode_init_security() calls, which have not yet
been converted to use the new callback function, such as those in
reiserfs and ocfs2, this patch defines security_old_inode_init_security().

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
2011-07-18 12:29:38 -04:00
Eric Paris 1dbe39424a xattr.h: expose string defines to userspace
af4f136056 ("security: move LSM xattrnames to xattr.h") moved the
XATTR_CAPS_SUFFIX define from capability.h to xattr.h.  This makes sense
except it was previously exports to userspace but xattr.h does not export
it to userspace.  This patch exports these headers to userspace to fix the
ABI regression.

There is some slight possibility that this will cause problems in other
applications which used these #defines differently (wrongly) and I could
JUST export the capabilities xattr name that we broke.  Does anyonehave an
idea how exposing these headers could cause a problem?

Below is what is being exposed to userspace, included here since it isn't
clear exactly what is going to be made available from the patch.

/* Namespaces */
#define XATTR_OS2_PREFIX "os2."
#define XATTR_OS2_PREFIX_LEN (sizeof (XATTR_OS2_PREFIX) - 1)

#define XATTR_SECURITY_PREFIX   "security."
#define XATTR_SECURITY_PREFIX_LEN (sizeof (XATTR_SECURITY_PREFIX) - 1)

#define XATTR_SYSTEM_PREFIX "system."
#define XATTR_SYSTEM_PREFIX_LEN (sizeof (XATTR_SYSTEM_PREFIX) - 1)

#define XATTR_TRUSTED_PREFIX "trusted."
#define XATTR_TRUSTED_PREFIX_LEN (sizeof (XATTR_TRUSTED_PREFIX) - 1)

#define XATTR_USER_PREFIX "user."
#define XATTR_USER_PREFIX_LEN (sizeof (XATTR_USER_PREFIX) - 1)

/* Security namespace */
#define XATTR_SELINUX_SUFFIX "selinux"
#define XATTR_NAME_SELINUX XATTR_SECURITY_PREFIX XATTR_SELINUX_SUFFIX

#define XATTR_SMACK_SUFFIX "SMACK64"
#define XATTR_SMACK_IPIN "SMACK64IPIN"
#define XATTR_SMACK_IPOUT "SMACK64IPOUT"
#define XATTR_NAME_SMACK XATTR_SECURITY_PREFIX XATTR_SMACK_SUFFIX
#define XATTR_NAME_SMACKIPIN    XATTR_SECURITY_PREFIX XATTR_SMACK_IPIN
#define XATTR_NAME_SMACKIPOUT   XATTR_SECURITY_PREFIX XATTR_SMACK_IPOUT

#define XATTR_CAPS_SUFFIX "capability"
#define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX

Reported-by: Ozan Çaglayan <ozan@pardus.org.tr>
Signed-off-by: Eric Paris <eparis@redhat.com>
Cc: Mimi Zohar <zohar@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25 08:39:45 -07:00
Casey Schaufler 7898e1f8e9 Subject: [PATCH] Smack: mmap controls for library containment
In the embedded world there are often situations
  where libraries are updated from a variety of sources,
  for a variety of reasons, and with any number of
  security characteristics. These differences
  might include privilege required for a given library
  provided interface to function properly, as occurs
  from time to time in graphics libraries. There are
  also cases where it is important to limit use of
  libraries based on the provider of the library and
  the security aware application may make choices
  based on that criteria.

  These issues are addressed by providing an additional
  Smack label that may optionally be assigned to an object,
  the SMACK64MMAP attribute. An mmap operation is allowed
  if there is no such attribute.

  If there is a SMACK64MMAP attribute the mmap is permitted
  only if a subject with that label has all of the access
  permitted a subject with the current task label.

  Security aware applications may from time to time
  wish to reduce their "privilege" to avoid accidental use
  of privilege. One case where this arises is the
  environment in which multiple sources provide libraries
  to perform the same functions. An application may know
  that it should eschew services made available from a
  particular vendor, or of a particular version.

  In support of this a secondary list of Smack rules has
  been added that is local to the task. This list is
  consulted only in the case where the global list has
  approved access. It can only further restrict access.
  Unlike the global last, if no entry is found on the
  local list access is granted. An application can add
  entries to its own list by writing to /smack/load-self.

  The changes appear large as they involve refactoring
  the list handling to accomodate there being more
  than one rule list.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-01-17 08:05:27 -08:00
Jarkko Sakkinen 5c6d1125f8 Smack: Transmute labels on specified directories
In a situation where Smack access rules allow processes
with multiple labels to write to a directory it is easy
to get into a situation where the directory gets cluttered
with files that the owner can't deal with because while
they could be written to the directory a process at the
label of the directory can't write them. This is generally
the desired behavior, but when it isn't it is a real
issue.

This patch introduces a new attribute SMACK64TRANSMUTE that
instructs Smack to create the file with the label of the directory
under certain circumstances.

A new access mode, "t" for transmute, is made available to
Smack access rules, which are expanded from "rwxa" to "rwxat".
If a file is created in a directory marked as transmutable
and if access was granted to perform the operation by a rule
that included the transmute mode, then the file gets the
Smack label of the directory instead of the Smack label of the
creating process.

Note that this is equivalent to creating an empty file at the
label of the directory and then having the other process write
to it. The transmute scheme requires that both the access rule
allows transmutation and that the directory be explicitly marked.

Signed-off-by: Jarkko Sakkinen <ext-jarkko.2.sakkinen@nokia.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2010-12-07 14:04:02 -08:00
Casey Schaufler 676dac4b1b This patch adds a new security attribute to Smack called
SMACK64EXEC. It defines label that is used while task is
running.

Exception: in smack_task_wait() child task is checked
for write access to parent task using label inherited
from the task that forked it.

Fixed issues from previous submit:
- SMACK64EXEC was not read when SMACK64 was not set.
- inode security blob was not updated after setting
  SMACK64EXEC
- inode security blob was not updated when removing
  SMACK64EXEC
2010-12-02 06:43:39 -08:00
Mimi Zohar af4f136056 security: move LSM xattrnames to xattr.h
Make the security extended attributes names global. Updated to move
the remaining Smack xattrs.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2010-08-02 15:34:57 +10:00
Stephen Hemminger bb4354538e fs: xattr_handler table should be const
The entries in xattr handler table should be immutable (ie const)
like other operation tables.

Later patches convert common filesystems. Uncoverted filesystems
will still work, but will generate a compiler warning.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-21 18:31:18 -04:00
Christoph Hellwig 431547b3c4 sanitize xattr handler prototypes
Add a flags argument to struct xattr_handler and pass it to all xattr
handler methods.  This allows using the same methods for multiple
handlers, e.g. for the ACL methods which perform exactly the same action
for the access and default ACLs, just using a different underlying
attribute.  With a little more groundwork it'll also allow sharing the
methods for the regular user/trusted/secure handlers in extN, ocfs2 and
jffs2 like it's already done for xfs in this patch.

Also change the inode argument to the handlers to a dentry to allow
using the handlers mechnism for filesystems that require it later,
e.g. cifs.

[with GFS2 bits updated by Steven Whitehouse <swhiteho@redhat.com>]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-16 12:16:49 -05:00