Ensure that POSIX ACLs checking, getting, and setting works correctly
for filesystems mountable with a filesystem idmapping ("fs_idmapping")
that want to support idmapped mounts ("mnt_idmapping").
Note that no filesystems mountable with an fs_idmapping do yet support
idmapped mounts. This is required infrastructure work to unblock this.
As we explained in detail in [1] the fs_idmapping is irrelevant for
getxattr() and setxattr() when mapping the ACL_{GROUP,USER} {g,u}ids
stored in the uapi struct posix_acl_xattr_entry in
posix_acl_fix_xattr_{from,to}_user().
But for acl_permission_check() and posix_acl_{g,s}etxattr_idmapped_mnt()
the fs_idmapping matters.
acl_permission_check():
During lookup POSIX ACLs are retrieved directly via i_op->get_acl() and
are returned via the kernel internal struct posix_acl which contains
e_{g,u}id members of type k{g,u}id_t that already take the
fs_idmapping into acccount.
For example, a POSIX ACL stored with u4 on the backing store is mapped
to k10000004 in the fs_idmapping. The mnt_idmapping remaps the POSIX ACL
to k20000004. In order to do that the fs_idmapping needs to be taken
into account but that doesn't happen yet (Again, this is a
counterfactual currently as fuse doesn't support idmapped mounts
currently. It's just used as a convenient example.):
fs_idmapping: u0:k10000000:r65536
mnt_idmapping: u0:v20000000:r65536
ACL_USER: k10000004
acl_permission_check()
-> check_acl()
-> get_acl()
-> i_op->get_acl() == fuse_get_acl()
-> posix_acl_from_xattr(u0:k10000000:r65536 /* fs_idmapping */, ...)
{
k10000004 = make_kuid(u0:k10000000:r65536 /* fs_idmapping */,
u4 /* ACL_USER */);
}
-> posix_acl_permission()
{
-1 = make_vfsuid(u0:v20000000:r65536 /* mnt_idmapping */,
&init_user_ns,
k10000004);
vfsuid_eq_kuid(-1, k10000004 /* caller_fsuid */)
}
In order to correctly map from the fs_idmapping into mnt_idmapping we
require the relevant fs_idmaping to be passed:
acl_permission_check()
-> check_acl()
-> get_acl()
-> i_op->get_acl() == fuse_get_acl()
-> posix_acl_from_xattr(u0:k10000000:r65536 /* fs_idmapping */, ...)
{
k10000004 = make_kuid(u0:k10000000:r65536 /* fs_idmapping */,
u4 /* ACL_USER */);
}
-> posix_acl_permission()
{
v20000004 = make_vfsuid(u0:v20000000:r65536 /* mnt_idmapping */,
u0:k10000000:r65536 /* fs_idmapping */,
k10000004);
vfsuid_eq_kuid(v20000004, k10000004 /* caller_fsuid */)
}
The initial_idmapping is only correct for the current situation because
all filesystems that currently support idmapped mounts do not support
being mounted with an fs_idmapping.
Note that ovl_get_acl() is used to retrieve the POSIX ACLs from the
relevant lower layer and the lower layer's mnt_idmapping needs to be
taken into account and so does the fs_idmapping. See 0c5fd887d2 ("acl:
move idmapped mount fixup into vfs_{g,s}etxattr()") for more details.
For posix_acl_{g,s}etxattr_idmapped_mnt() it is not as obvious why the
fs_idmapping matters as it is for acl_permission_check(). Especially
because it doesn't matter for posix_acl_fix_xattr_{from,to}_user() (See
[1] for more context.).
Because posix_acl_{g,s}etxattr_idmapped_mnt() operate on the uapi
struct posix_acl_xattr_entry which contains {g,u}id_t values and thus
give the impression that the fs_idmapping is irrelevant as at this point
appropriate {g,u}id_t values have seemlingly been generated.
As we've stated multiple times this assumption is wrong and in fact the
uapi struct posix_acl_xattr_entry is taking idmappings into account
depending at what place it is operated on.
posix_acl_getxattr_idmapped_mnt()
When posix_acl_getxattr_idmapped_mnt() is called the values stored in
the uapi struct posix_acl_xattr_entry are mapped according to the
fs_idmapping. This happened when they were read from the backing store
and then translated from struct posix_acl into the uapi
struct posix_acl_xattr_entry during posix_acl_to_xattr().
In other words, the fs_idmapping matters as the values stored as
{g,u}id_t in the uapi struct posix_acl_xattr_entry have been generated
by it.
So we need to take the fs_idmapping into account during make_vfsuid()
in posix_acl_getxattr_idmapped_mnt().
posix_acl_setxattr_idmapped_mnt()
When posix_acl_setxattr_idmapped_mnt() is called the values stored as
{g,u}id_t in uapi struct posix_acl_xattr_entry are intended to be the
values that ultimately get turned back into a k{g,u}id_t in
posix_acl_from_xattr() (which turns the uapi
struct posix_acl_xattr_entry into the kernel internal struct posix_acl).
In other words, the fs_idmapping matters as the values stored as
{g,u}id_t in the uapi struct posix_acl_xattr_entry are intended to be
the values that will be undone in the fs_idmapping when writing to the
backing store.
So we need to take the fs_idmapping into account during from_vfsuid()
in posix_acl_setxattr_idmapped_mnt().
Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1]
Fixes: 0c5fd887d2 ("acl: move idmapped mount fixup into vfs_{g,s}etxattr()")
Cc: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Link: https://lore.kernel.org/r/20220816113514.43304-1-brauner@kernel.org
The ovl_get_acl() function needs to alter the POSIX ACLs retrieved from the
lower filesystem. Instead of hand-rolling a overlayfs specific
posix_acl_clone() variant allow export it. It's not special and it's not deeply
internal anyway.
Link: https://lore.kernel.org/r/20220708090134.385160-3-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>
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>
Last cycle we extended the idmapped mounts infrastructure to support
idmapped mounts of idmapped filesystems (No such filesystem yet exist.).
Since then, the meaning of an idmapped mount is a mount whose idmapping
is different from the filesystems idmapping.
While doing that work we missed to adapt the acl translation helpers.
They still assume that checking for the identity mapping is enough. But
they need to use the no_idmapping() helper instead.
Note, POSIX ACLs are always translated right at the userspace-kernel
boundary using the caller's current idmapping and the initial idmapping.
The order depends on whether we're coming from or going to userspace.
The filesystem's idmapping doesn't matter at the border.
Consequently, if a non-idmapped mount is passed we need to make sure to
always pass the initial idmapping as the mount's idmapping and not the
filesystem idmapping. Since it's irrelevant here it would yield invalid
ids and prevent setting acls for filesystems that are mountable in a
userns and support posix acls (tmpfs and fuse).
I verified the regression reported in [1] and verified that this patch
fixes it. A regression test will be added to xfstests in parallel.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215849 [1]
Fixes: bd303368b7 ("fs: support mapped mounts of mapped filesystems")
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org> # 5.17
Cc: <regressions@lists.linux.dev>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In previous patches we added new and modified existing helpers to handle
idmapped mounts of filesystems mounted with an idmapping. In this final
patch we convert all relevant places in the vfs to actually pass the
filesystem's idmapping into these helpers.
With this the vfs is in shape to handle idmapped mounts of filesystems
mounted with an idmapping. Note that this is just the generic
infrastructure. Actually adding support for idmapped mounts to a
filesystem mountable with an idmapping is follow-up work.
In this patch we extend the definition of an idmapped mount from a mount
that that has the initial idmapping attached to it to a mount that has
an idmapping attached to it which is not the same as the idmapping the
filesystem was mounted with.
As before we do not allow the initial idmapping to be attached to a
mount. In addition this patch prevents that the idmapping the filesystem
was mounted with can be attached to a mount created based on this
filesystem.
This has multiple reasons and advantages. First, attaching the initial
idmapping or the filesystem's idmapping doesn't make much sense as in
both cases the values of the i_{g,u}id and other places where k{g,u}ids
are used do not change. Second, a user that really wants to do this for
whatever reason can just create a separate dedicated identical idmapping
to attach to the mount. Third, we can continue to use the initial
idmapping as an indicator that a mount is not idmapped allowing us to
continue to keep passing the initial idmapping into the mapping helpers
to tell them that something isn't an idmapped mount even if the
filesystem is mounted with an idmapping.
Link: https://lore.kernel.org/r/20211123114227.3124056-11-brauner@kernel.org (v1)
Link: https://lore.kernel.org/r/20211130121032.3753852-11-brauner@kernel.org (v2)
Link: https://lore.kernel.org/r/20211203111707.3901969-11-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
The low-level mapping helpers were so far crammed into fs.h. They are
out of place there. The fs.h header should just contain the higher-level
mapping helpers that interact directly with vfs objects such as struct
super_block or struct inode and not the bare mapping helpers. Similarly,
only vfs and specific fs code shall interact with low-level mapping
helpers. And so they won't be made accessible automatically through
regular {g,u}id helpers.
Link: https://lore.kernel.org/r/20211123114227.3124056-3-brauner@kernel.org (v1)
Link: https://lore.kernel.org/r/20211130121032.3753852-3-brauner@kernel.org (v2)
Link: https://lore.kernel.org/r/20211203111707.3901969-3-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
The fallthrough comment for an ignored cmpxchg() return value produces a
harmless warning with 'make W=1':
fs/posix_acl.c: In function 'get_acl':
fs/posix_acl.c:127:36: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
127 | /* fall through */ ;
| ^
Simplify it as a step towards a clean W=1 build. As all architectures
define cmpxchg() as a statement expression these days, it is no longer
necessary to evaluate its return code, and the if() can just be droped.
Link: https://lkml.kernel.org/r/20210927102410.1863853-1-arnd@kernel.org
Link: https://lore.kernel.org/all/20210322132103.qiun2rjilnlgztxe@wittgenstein/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: James Morris <jamorris@linux.microsoft.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Overlayfs does not cache ACL's (to avoid double caching). Instead it just
calls the underlying filesystem's i_op->get_acl(), which will return the
cached value, if possible.
In rcu path walk, however, get_cached_acl_rcu() is employed to get the
value from the cache, which will fail on overlayfs resulting in dropping
out of rcu walk mode. This can result in a big performance hit in certain
situations.
Fix by calling ->get_acl() with rcu=true in case of ACL_DONT_CACHE (which
indicates pass-through)
Reported-by: garyhuang <zjh.20052005@163.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Add a rcu argument to the ->get_acl() callback to allow
get_cached_acl_rcu() to call the ->get_acl() method in the next patch.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.
As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.
Link: https://lore.kernel.org/r/20210121131959.646623-25-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>
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>
The inode_owner_or_capable() helper determines whether the caller is the
owner of the inode or is capable with respect to that inode. Allow it to
handle idmapped mounts. If the inode is accessed through an idmapped
mount it according to the mount's user namespace. Afterwards the checks
are identical to non-idmapped mounts. If the initial user namespace is
passed nothing changes so non-idmapped mounts will see identical
behavior as before.
Similarly, allow the inode_init_owner() helper to handle idmapped
mounts. It initializes a new inode on idmapped mounts by mapping the
fsuid and fsgid of the caller from the mount's user namespace. If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-7-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: Christian Brauner <christian.brauner@ubuntu.com>
The two helpers inode_permission() and generic_permission() are used by
the vfs to perform basic permission checking by verifying that the
caller is privileged over an inode. In order to handle idmapped mounts
we extend the two helpers with an additional user namespace argument.
On idmapped mounts the two helpers will make sure to map the inode
according to the mount's user namespace and then peform identical
permission checks to inode_permission() and generic_permission(). If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-6-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>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
In order to determine whether a caller holds privilege over a given
inode the capability framework exposes the two helpers
privileged_wrt_inode_uidgid() and capable_wrt_inode_uidgid(). The former
verifies that the inode has a mapping in the caller's user namespace and
the latter additionally verifies that the caller has the requested
capability in their current user namespace.
If the inode is accessed through an idmapped mount map it into the
mount's user namespace. Afterwards the checks are identical to
non-idmapped inodes. If the initial user namespace is passed all
operations are a nop so non-idmapped mounts will not see a change in
behavior.
Link: https://lore.kernel.org/r/20210121131959.646623-5-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>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
posix_acl_permission() does not care about MAY_NOT_BLOCK, and in fact
the permission logic internally must not check that bit (it's only for
upper layers to decide whether they can block to do IO to look up the
acl information or not).
But the way the code was written, it _looked_ like it cared, since the
function explicitly did not mask that bit off.
But it has exactly two callers: one for when that bit is set, which
first clears the bit before calling posix_acl_permission(), and the
other call site when that bit was clear.
So stop the silly games "saving" the MAY_NOT_BLOCK bit that must not be
used for the actual permission test, and that currently is pointlessly
cleared by the callers when the function itself should just not care.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix kernel-doc warnings in fs/posix_acl.c.
Also fix one typo (setgit -> setgid).
fs/posix_acl.c:647: warning: Function parameter or member 'inode' not described in 'posix_acl_update_mode'
fs/posix_acl.c:647: warning: Function parameter or member 'mode_p' not described in 'posix_acl_update_mode'
fs/posix_acl.c:647: warning: Function parameter or member 'acl' not described in 'posix_acl_update_mode'
Link: http://lkml.kernel.org/r/29b0dc46-1f28-a4e5-b1d0-ba2b65629779@infradead.org
Fixes: 073931017b ("posix_acl: Clear SGID bit when setting file permissions")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add SPDX license identifiers to all files which:
- Have no license information of any form
- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
atomic_t variables are currently used to implement reference
counters with the following properties:
- counter is initialized to 1 using atomic_set()
- a resource is freed upon counter reaching zero
- once counter reaches zero, its further
increments aren't allowed
- counter schema uses basic atomic operations
(set, inc, inc_not_zero, dec_and_test, etc.)
Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.
The variable posix_acl.a_refcount is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
**Important note for maintainers:
Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.
The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.
Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.
Please double check that you don't have some undocumented
memory guarantees for this variable usage.
For the posix_acl.a_refcount it might make a difference
in following places:
- get_cached_acl(): increment in refcount_inc_not_zero() only
guarantees control dependency on success vs. fully ordered
atomic counterpart. However this operation is performed under
rcu_read_lock(), so this should be fine.
- posix_acl_release(): decrement in refcount_dec_and_test() only
provides RELEASE ordering and control dependency on success
vs. fully ordered atomic counterpart
Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Add #include <linux/cred.h> dependencies to all .c files rely on sched.h
doing that for them.
Note that even if the count where we need to add extra headers seems high,
it's still a net win, because <linux/sched.h> is included in over
2,200 files ...
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This change was missed the tmpfs modification in In CVE-2016-7097
commit 073931017b ("posix_acl: Clear SGID bit when setting
file permissions")
It can test by xfstest generic/375, which failed to clear
setgid bit in the following test case on tmpfs:
touch $testfile
chown 100:100 $testfile
chmod 2755 $testfile
_runas -u 100 -g 101 -- setfacl -m u::rwx,g::rwx,o::rwx $testfile
Signed-off-by: Gu Zheng <guzheng1@huawei.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull more vfs updates from Al Viro:
">rename2() work from Miklos + current_time() from Deepa"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: Replace current_fs_time() with current_time()
fs: Replace CURRENT_TIME_SEC with current_time() for inode timestamps
fs: Replace CURRENT_TIME with current_time() for inode timestamps
fs: proc: Delete inode time initializations in proc_alloc_inode()
vfs: Add current_time() api
vfs: add note about i_op->rename changes to porting
fs: rename "rename2" i_op to "rename"
vfs: remove unused i_op->rename
fs: make remaining filesystems use .rename2
libfs: support RENAME_NOREPLACE in simple_rename()
fs: support RENAME_NOREPLACE for local filesystems
ncpfs: fix unused variable warning
Remove the unnecessary typedefs and the zero-length a_entries array in
struct posix_acl_xattr_header.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
CURRENT_TIME macro is not appropriate for filesystems as it
doesn't use the right granularity for filesystem timestamps.
Use current_time() instead.
CURRENT_TIME is also not y2038 safe.
This is also in preparation for the patch that transitions
vfs timestamps to use 64 bit time and hence make them
y2038 safe. As part of the effort current_time() will be
extended to do range checks. Hence, it is necessary for all
file system timestamps to use current_time(). Also,
current_time() will be transitioned along with vfs to be
y2038 safe.
Note that whenever a single call to current_time() is used
to change timestamps in different inodes, it is because they
share the same time granularity.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Felipe Balbi <balbi@kernel.org>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
When file permissions are modified via chmod(2) and the user is not in
the owning group or capable of CAP_FSETID, the setgid bit is cleared in
inode_change_ok(). Setting a POSIX ACL via setxattr(2) sets the file
permissions as well as the new ACL, but doesn't clear the setgid bit in
a similar way; this allows to bypass the check in chmod(2). Fix that.
References: CVE-2016-7097
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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.
...
Update posix_acl_valid to verify that an acl is within a user namespace.
Update the callers of posix_acl_valid to pass in an appropriate
user namespace. For posix_acl_xattr_set and v9fs_xattr_set_acl pass in
inode->i_sb->s_user_ns to posix_acl_valid. For md_unpack_acl pass in
&init_user_ns as no inode or superblock is in sight.
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Factor out part of posix_acl_xattr_set into a common function that takes
a posix_acl, which nfsd can also call.
The prototype already exists in include/linux/posix_acl.h.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: stable@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
acl_by_type(inode, type) returns a pointer to either inode->i_acl or
inode->i_default_acl depending on type. This is useful in
fs/posix_acl.c, but should never have been visible outside that file.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
When get_acl() is called for an inode whose ACL is not cached yet, the
get_acl inode operation is called to fetch the ACL from the filesystem.
The inode operation is responsible for updating the cached acl with
set_cached_acl(). This is done without locking at the VFS level, so
another task can call set_cached_acl() or forget_cached_acl() before the
get_acl inode operation gets to calling set_cached_acl(), and then
get_acl's call to set_cached_acl() results in caching an outdate ACL.
Prevent this from happening by setting the cached ACL pointer to a
task-specific sentinel value before calling the get_acl inode operation.
Move the responsibility for updating the cached ACL from the get_acl
inode operations to get_acl(). There, only set the cached ACL if the
sentinel value hasn't changed.
The sentinel values are chosen to have odd values. Likewise, the value
of ACL_NOT_CACHED is odd. In contrast, ACL object pointers always have
an even value (ACLs are aligned in memory). This allows to distinguish
uncached ACLs values from ACL objects.
In addition, switch from guarding inode->i_acl and inode->i_default_acl
upates by the inode->i_lock spinlock to using xchg() and cmpxchg().
Filesystems that do not want ACLs returned from their get_acl inode
operations to be cached must call forget_cached_acl() to prevent the VFS
from doing so.
(Patch written by Al Viro and Andreas Gruenbacher.)
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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>
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>
Remove POSIX_ACL_XATTR_{ACCESS,DEFAULT} and GFS2_POSIX_ACL_{ACCESS,DEFAULT}
and replace them with the definitions in <include/uapi/linux/xattr.h>.
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>
The xattr_handler operations are currently all passed a file system
specific flags value which the operations can use to disambiguate between
different handlers; some file systems use that to distinguish the xattr
namespace, for example. In some oprations, it would be useful to also have
access to the handler prefix. To allow that, pass a pointer to the handler
to operations instead of the flags value alone.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
When a filesystem that contains POSIX ACLs is mounted without ACL support
(-o noacl), the appropriate behavior is not to list any existing POSIX ACL
xattrs. The return value for list xattr handlers in this case is 0, not an
error code: several filesystems that use the POSIX ACL xattr handlers do
not expect the list operation to fail.
Symlinks cannot have ACLs, so posix_acl_xattr_list will never be called for
symlinks in the first place.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The get and set operations of the POSIX ACL xattr handlers failed to check
the attribute names, so all names with "system.posix_acl_access" or
"system.posix_acl_default" as a prefix were accepted. Reject invalid names
from now on.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
If posix_acl_create() returns an error code then "*acl" and "*default_acl"
can be uninitialized or point to freed memory. This is a dangerous thing
to do. For example, it causes a problem in ocfs2_reflink():
fs/ocfs2/refcounttree.c:4327 ocfs2_reflink()
error: potentially using uninitialized 'default_acl'.
I've re-written this so we set the pointers to NULL at the start. I've
added a temporary "clone" variable to hold the value of "*acl" until end.
Setting them to NULL means means we don't need the "no_acl" label. We may
as well remove the "apply_umask" stuff forward and remove that label as
well.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Convert the following where appropriate:
(1) S_ISLNK(dentry->d_inode) to d_is_symlink(dentry).
(2) S_ISREG(dentry->d_inode) to d_is_reg(dentry).
(3) S_ISDIR(dentry->d_inode) to d_is_dir(dentry). This is actually more
complicated than it appears as some calls should be converted to
d_can_lookup() instead. The difference is whether the directory in
question is a real dir with a ->lookup op or whether it's a fake dir with
a ->d_automount op.
In some circumstances, we can subsume checks for dentry->d_inode not being
NULL into this, provided we the code isn't in a filesystem that expects
d_inode to be NULL if the dirent really *is* negative (ie. if we're going to
use d_inode() rather than d_backing_inode() to get the inode pointer).
Note that the dentry type field may be set to something other than
DCACHE_MISS_TYPE when d_inode is NULL in the case of unionmount, where the VFS
manages the fall-through from a negative dentry to a lower layer. In such a
case, the dentry type of the negative union dentry is set to the same as the
type of the lower dentry.
However, if you know d_inode is not NULL at the call site, then you can use
the d_is_xxx() functions even in a filesystem.
There is one further complication: a 0,0 chardev dentry may be labelled
DCACHE_WHITEOUT_TYPE rather than DCACHE_SPECIAL_TYPE. Strictly, this was
intended for special directory entry types that don't have attached inodes.
The following perl+coccinelle script was used:
use strict;
my @callers;
open($fd, 'git grep -l \'S_IS[A-Z].*->d_inode\' |') ||
die "Can't grep for S_ISDIR and co. callers";
@callers = <$fd>;
close($fd);
unless (@callers) {
print "No matches\n";
exit(0);
}
my @cocci = (
'@@',
'expression E;',
'@@',
'',
'- S_ISLNK(E->d_inode->i_mode)',
'+ d_is_symlink(E)',
'',
'@@',
'expression E;',
'@@',
'',
'- S_ISDIR(E->d_inode->i_mode)',
'+ d_is_dir(E)',
'',
'@@',
'expression E;',
'@@',
'',
'- S_ISREG(E->d_inode->i_mode)',
'+ d_is_reg(E)' );
my $coccifile = "tmp.sp.cocci";
open($fd, ">$coccifile") || die $coccifile;
print($fd "$_\n") || die $coccifile foreach (@cocci);
close($fd);
foreach my $file (@callers) {
chomp $file;
print "Processing ", $file, "\n";
system("spatch", "--sp-file", $coccifile, $file, "--in-place", "--no-show-diff") == 0 ||
die "spatch failed";
}
[AV: overlayfs parts skipped]
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
get_acl gets a reference which we must release in the error cases.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Various filesystems don't bother checking for a NULL ACL in
posix_acl_equiv_mode, and thus can dereference a NULL pointer when it
gets passed one. This usually happens from the NFS server, as the ACL tools
never pass a NULL ACL, but instead of one representing the mode bits.
Instead of adding boilerplat to all filesystems put this check into one place,
which will allow us to remove the check from other filesystems as well later
on.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Ben Greear <greearb@candelatech.com>
Reported-by: Marco Munderloh <munderl@tnt.uni-hannover.de>,
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
but instead the widening contributor base. It is good to see that
interest is increasing in GFS2, and I'd like to thank all the
contributors to this patch set.
In addition to the usual set of bug fixes and clean ups, there are
patches to improve inode creation performance when xattrs are
required and some improvements to the transaction code which is
intended to help improve scalability after further changes in due
course.
Journal extent mapping is also updated to make it more efficient
and again, this is a foundation for future work in this area.
The maximum number of ACLs has been increased to 300 (for a 4k
block size) which means that even with a few additional xattrs
from selinux, everything should fit within a single fs block.
There is also a patch to bring GFS2's own copy of the writepages
code up to the same level as the core VFS. Eventually we may be
able to merge some of this code, since it is fairly similar.
The other major change this time, is bringing consistency to
the printing of messages via fs_<level>, pr_<level> macros.
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Merge tag 'gfs2-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-3.0-nmw
Pull GFS2 updates from Steven Whitehouse:
"One of the main highlights this time, is not the patches themselves
but instead the widening contributor base. It is good to see that
interest is increasing in GFS2, and I'd like to thank all the
contributors to this patch set.
In addition to the usual set of bug fixes and clean ups, there are
patches to improve inode creation performance when xattrs are required
and some improvements to the transaction code which is intended to
help improve scalability after further changes in due course.
Journal extent mapping is also updated to make it more efficient and
again, this is a foundation for future work in this area.
The maximum number of ACLs has been increased to 300 (for a 4k block
size) which means that even with a few additional xattrs from selinux,
everything should fit within a single fs block.
There is also a patch to bring GFS2's own copy of the writepages code
up to the same level as the core VFS. Eventually we may be able to
merge some of this code, since it is fairly similar.
The other major change this time, is bringing consistency to the
printing of messages via fs_<level>, pr_<level> macros"
* tag 'gfs2-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-3.0-nmw: (29 commits)
GFS2: Fix address space from page function
GFS2: Fix uninitialized VFS inode in gfs2_create_inode
GFS2: Fix return value in slot_get()
GFS2: inline function gfs2_set_mode
GFS2: Remove extraneous function gfs2_security_init
GFS2: Increase the max number of ACLs
GFS2: Re-add a call to log_flush_wait when flushing the journal
GFS2: Ensure workqueue is scheduled after noexp request
GFS2: check NULL return value in gfs2_ok_to_move
GFS2: Convert gfs2_lm_withdraw to use fs_err
GFS2: Use fs_<level> more often
GFS2: Use pr_<level> more consistently
GFS2: Move recovery variables to journal structure in memory
GFS2: global conversion to pr_foo()
GFS2: return -E2BIG if hit the maximum limits of ACLs
GFS2: Clean up journal extent mapping
GFS2: replace kmalloc - __vmalloc / memset 0
GFS2: Remove extra "if" in gfs2_log_flush()
fs: NULL dereference in posix_acl_to_xattr()
GFS2: Move log buffer accounting to transaction
...
This patch moves the dereference of "buffer" after the check for NULL.
The only place which passes a NULL parameter is gfs2_set_acl().
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
posix_acl_xattr_get requires get_acl() to return EOPNOTSUPP if the
filesystem cannot support acls. This is needed for NFS, which can't
know whether or not the server supports acls until it tries to get/set
one.
This patch converts posix_acl_chmod and posix_acl_create to deal with
EOPNOTSUPP return values from get_acl().
Reported-by: Russell King <linux@arm.linux.org.uk>
Link: http://lkml.kernel.org/r/20140130140834.GW15937@n2100.arm.linux.org.uk
Cc: Al Viro viro@zeniv.linux.org.uk>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
