On Tue, Jul 05, 2022 at 04:45:02PM +0200, Christian Brauner wrote:
> 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}
>
> 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.
>
> Similarly, the user creates another idmapped mount using the same idmapping:
>
> mount-idmapped/mount-idmapped --map-mount=b:0:10000000:65536 \
> /vol/contpool/ctrover/ \
> /vol/contpool/overmap/
>
> 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()
> | | {
> | | /* This is a nop on non-idmapped mounts. */
> | | 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() |
> | { |
> | /* This is a nop on non-idmapped mounts. */ 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);
> }
Hi Christian,
Trying to understand the problem and solution. I am wondering
why do we still have posix_acl_fix_xattr_to_user().
Shouldn't posix_acl_getxattr_idmapped_mnt() (Or whatever name is
appropriate), take care of doing all the translations. Something along
the lines of cap_inode_getsecurity().
IOW, I am viewing it as if posix_acl_getxattr_idmapped_mnt() takes
care of doing all the translations for each layer. And it is called
twice for stacked filesystem. So for the example when overaly is mounted
from outside the user_ns.
idmapped mount lower: 0:10000000:65536
caller's idmapping: 0:10000000:65536
overlayfs idmapping (ofs->creator_cred): 0:0:4k /* initial idmapping */
Overlay layer translations
10000004 = make_kuid(&init_user_ns, 10000004);
/* Overlayfs mount has no idmapping */
10000004 = mapped_kuid_fs(&init_user_ns, &init_user_ns, 10000004);
/* Map into caller's idmapping. And caller in this case is process
* inside user namespace */
4 = from_kuid(0:10000000:65536, 10000004);
Lower layer translations
4 = make_kuid(&init_user_ns, 4);
10000004 = mapped_kuid_fs(0:10000000:65536 /* lower idmapped mount */, &init_user_ns, 4);
/* Map into caller's idmapping. And caller in this case is mounter
* of overlayfs which is init_user_ns */
10000004 = from_kuid(&init_user_ns, 10000004);
Above kind of makes more sense to me based on your documentation here.
https://www.kernel.org/doc/html/latest/filesystems/idmappings.html
But there is a good chance that I am missing something.
And when overlayfs is mounted from inside user namepsace, then
translations could look as follows.
idmapped mount lower: 0:10000000:65536
caller's idmapping: 0:10000000:65536
overlayfs idmapping (ofs->creator_cred): 0:10000000:65536
Overlay layer translations
/* Overlayfs was mounted from inside user namespace */
10000004 = make_kuid(0:10000000:65536, 4);
/* Overlayfs mount has no idmapping */
10000004 = mapped_kuid_fs(&init_user_ns, 0:10000000:65536, 10000004);
/* Map into caller's idmapping. And caller in this case is process
* inside user namespace */
4 = from_kuid(0:10000000:65536, 10000004);
Lower layer translations
4 = make_kuid(&init_user_ns, 4);
10000004 = mapped_kuid_fs(0:10000000:65536 /* lower idmapped mount */, &init_user_ns, 4);
/* Map into caller's idmapping. And caller in this case is mounter
* of overlayfs which was inside user namespace */
4 = from_kuid(0:10000000:65536, 10000004);
> And similarly if the user chooses option (1) and mounted overayfs on top of
You probably mean if "user chooses option (2)". And following example
also seems to be for option 1 and not option 2.
Thanks
Vivek
> 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()
> | | {
> | | /* This is a nop on non-idmapped mounts. */
> | | 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() |
> | { |
> | /* This is a nop on non-idmapped mounts. */ V
> | 10000004 = make_kuid(&init_user_ns, 10000004);
In this example, overlayfs is mounted from inside the user namespace,
so overlay filesystem idmappings are not init_user_ns. Should this be
following instead.
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);
> }
>
> Link: https://github.com/brauner/mount-idmapped/issues/9
> Cc: Seth Forshee <sforshee@xxxxxxxxxxxxxxxx>
> Cc: Amir Goldstein <amir73il@xxxxxxxxx>
> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Aleksa Sarai <cyphar@xxxxxxxxxx>
> Cc: Miklos Szeredi <mszeredi@xxxxxxxxxx>
> Cc: linux-unionfs@xxxxxxxxxxxxxxx
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx
> Signed-off-by: Christian Brauner (Microsoft) <brauner@xxxxxxxxxx>
> ---
> Hey,
>
> This passes the following tests:
>
> sudo ./check -g quick
> sudo ./check -g idmapped # always running that even though it's part of -g quick
> sudo ./check -overlay
> sudo ./check -overlay # export IDMAPPED_MOUNTS=true
> sudo ./check -overlay -g overlay/union
> sudo ./runltp # running the full LTP testsuite
>
> We don't need a fixes tag since this work is only going to be released with v5.19.
>
> Thanks!
> Christian
> ---
> fs/ksmbd/vfs.c | 2 +-
> fs/ksmbd/vfs.h | 2 +-
> fs/overlayfs/overlayfs.h | 2 +-
> fs/posix_acl.c | 133 +++++++++++++++++++++++---------
> fs/xattr.c | 24 ++++--
> include/linux/capability.h | 2 +-
> include/linux/posix_acl_xattr.h | 32 +++++---
> include/linux/xattr.h | 2 +-
> security/commoncap.c | 2 +-
> 9 files changed, 139 insertions(+), 62 deletions(-)
>
> diff --git a/fs/ksmbd/vfs.c b/fs/ksmbd/vfs.c
> index 05efcdf7a4a7..7c849024999f 100644
> --- a/fs/ksmbd/vfs.c
> +++ b/fs/ksmbd/vfs.c
> @@ -963,7 +963,7 @@ ssize_t ksmbd_vfs_getxattr(struct user_namespace *user_ns,
> */
> int ksmbd_vfs_setxattr(struct user_namespace *user_ns,
> struct dentry *dentry, const char *attr_name,
> - const void *attr_value, size_t attr_size, int flags)
> + void *attr_value, size_t attr_size, int flags)
> {
> int err;
>
> diff --git a/fs/ksmbd/vfs.h b/fs/ksmbd/vfs.h
> index 8c37aaf936ab..70da4c0ba7ad 100644
> --- a/fs/ksmbd/vfs.h
> +++ b/fs/ksmbd/vfs.h
> @@ -109,7 +109,7 @@ ssize_t ksmbd_vfs_casexattr_len(struct user_namespace *user_ns,
> int attr_name_len);
> int ksmbd_vfs_setxattr(struct user_namespace *user_ns,
> struct dentry *dentry, const char *attr_name,
> - const void *attr_value, size_t attr_size, int flags);
> + void *attr_value, size_t attr_size, int flags);
> int ksmbd_vfs_xattr_stream_name(char *stream_name, char **xattr_stream_name,
> size_t *xattr_stream_name_size, int s_type);
> int ksmbd_vfs_remove_xattr(struct user_namespace *user_ns,
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index 4f34b7e02eee..9c793a42eda6 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -256,7 +256,7 @@ static inline ssize_t ovl_path_getxattr(struct ovl_fs *ofs,
> }
>
> static inline int ovl_do_setxattr(struct ovl_fs *ofs, struct dentry *dentry,
> - const char *name, const void *value,
> + const char *name, void *value,
> size_t size, int flags)
> {
> int err = vfs_setxattr(ovl_upper_mnt_userns(ofs), dentry, name, value, size, flags);
> diff --git a/fs/posix_acl.c b/fs/posix_acl.c
> index 962d32468eb4..7eeb2c327b59 100644
> --- a/fs/posix_acl.c
> +++ b/fs/posix_acl.c
> @@ -710,10 +710,30 @@ EXPORT_SYMBOL(posix_acl_update_mode);
> /*
> * Fix up the uids and gids in posix acl extended attributes in place.
> */
> -static void posix_acl_fix_xattr_userns(
> - struct user_namespace *to, struct user_namespace *from,
> - struct user_namespace *mnt_userns,
> - void *value, size_t size, bool from_user)
> +static int posix_acl_fix_xattr_common(void *value, size_t size)
> +{
> + struct posix_acl_xattr_header *header = value;
> + int count;
> +
> + if (!header)
> + return -EINVAL;
> + if (size < sizeof(struct posix_acl_xattr_header))
> + return -EINVAL;
> + if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
> + return -EINVAL;
> +
> + count = posix_acl_xattr_count(size);
> + if (count < 0)
> + return -EINVAL;
> + if (count == 0)
> + return -EINVAL;
> +
> + return count;
> +}
> +
> +void posix_acl_getxattr_idmapped_mnt(struct user_namespace *mnt_userns,
> + const struct inode *inode,
> + void *value, size_t size)
> {
> struct posix_acl_xattr_header *header = value;
> struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
> @@ -721,35 +741,88 @@ static void posix_acl_fix_xattr_userns(
> kuid_t uid;
> kgid_t gid;
>
> - if (!value)
> + if (no_idmapping(mnt_userns, i_user_ns(inode)))
> return;
> - if (size < sizeof(struct posix_acl_xattr_header))
> +
> + count = posix_acl_fix_xattr_common(value, size);
> + if (count < 0)
> return;
> - if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
> +
> + for (end = entry + count; entry != end; entry++) {
> + switch (le16_to_cpu(entry->e_tag)) {
> + case ACL_USER:
> + uid = make_kuid(&init_user_ns, le32_to_cpu(entry->e_id));
> + uid = mapped_kuid_fs(mnt_userns, &init_user_ns, uid);
> + entry->e_id = cpu_to_le32(from_kuid(&init_user_ns, uid));
> + break;
> + case ACL_GROUP:
> + gid = make_kgid(&init_user_ns, le32_to_cpu(entry->e_id));
> + gid = mapped_kgid_fs(mnt_userns, &init_user_ns, gid);
> + entry->e_id = cpu_to_le32(from_kgid(&init_user_ns, gid));
> + break;
> + default:
> + break;
> + }
> + }
> +}
> +
> +void posix_acl_setxattr_idmapped_mnt(struct user_namespace *mnt_userns,
> + const struct inode *inode,
> + void *value, size_t size)
> +{
> + struct posix_acl_xattr_header *header = value;
> + struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
> + int count;
> + kuid_t uid;
> + kgid_t gid;
> +
> + if (no_idmapping(mnt_userns, i_user_ns(inode)))
> return;
>
> - count = posix_acl_xattr_count(size);
> + count = posix_acl_fix_xattr_common(value, size);
> if (count < 0)
> return;
> - if (count == 0)
> +
> + for (end = entry + count; entry != end; entry++) {
> + switch (le16_to_cpu(entry->e_tag)) {
> + case ACL_USER:
> + uid = make_kuid(&init_user_ns, le32_to_cpu(entry->e_id));
> + uid = mapped_kuid_user(mnt_userns, &init_user_ns, uid);
> + entry->e_id = cpu_to_le32(from_kuid(&init_user_ns, uid));
> + break;
> + case ACL_GROUP:
> + gid = make_kgid(&init_user_ns, le32_to_cpu(entry->e_id));
> + gid = mapped_kgid_user(mnt_userns, &init_user_ns, gid);
> + entry->e_id = cpu_to_le32(from_kgid(&init_user_ns, gid));
> + break;
> + default:
> + break;
> + }
> + }
> +}
> +
> +static void posix_acl_fix_xattr_userns(
> + struct user_namespace *to, struct user_namespace *from,
> + void *value, size_t size)
> +{
> + struct posix_acl_xattr_header *header = value;
> + struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
> + int count;
> + kuid_t uid;
> + kgid_t gid;
> +
> + count = posix_acl_fix_xattr_common(value, size);
> + if (count < 0)
> return;
>
> for (end = entry + count; entry != end; entry++) {
> switch(le16_to_cpu(entry->e_tag)) {
> case ACL_USER:
> uid = make_kuid(from, le32_to_cpu(entry->e_id));
> - if (from_user)
> - uid = mapped_kuid_user(mnt_userns, &init_user_ns, uid);
> - else
> - uid = mapped_kuid_fs(mnt_userns, &init_user_ns, uid);
> entry->e_id = cpu_to_le32(from_kuid(to, uid));
> break;
> case ACL_GROUP:
> gid = make_kgid(from, le32_to_cpu(entry->e_id));
> - if (from_user)
> - gid = mapped_kgid_user(mnt_userns, &init_user_ns, gid);
> - else
> - gid = mapped_kgid_fs(mnt_userns, &init_user_ns, gid);
> entry->e_id = cpu_to_le32(from_kgid(to, gid));
> break;
> default:
> @@ -758,34 +831,20 @@ static void posix_acl_fix_xattr_userns(
> }
> }
>
> -void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns,
> - struct inode *inode,
> - void *value, size_t size)
> +void posix_acl_fix_xattr_from_user(void *value, size_t size)
> {
> struct user_namespace *user_ns = current_user_ns();
> -
> - /* Leave ids untouched on non-idmapped mounts. */
> - if (no_idmapping(mnt_userns, i_user_ns(inode)))
> - mnt_userns = &init_user_ns;
> - if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
> + if (user_ns == &init_user_ns)
> return;
> - posix_acl_fix_xattr_userns(&init_user_ns, user_ns, mnt_userns, value,
> - size, true);
> + posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
> }
>
> -void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns,
> - struct inode *inode,
> - void *value, size_t size)
> +void posix_acl_fix_xattr_to_user(void *value, size_t size)
> {
> struct user_namespace *user_ns = current_user_ns();
> -
> - /* Leave ids untouched on non-idmapped mounts. */
> - if (no_idmapping(mnt_userns, i_user_ns(inode)))
> - mnt_userns = &init_user_ns;
> - if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
> + if (user_ns == &init_user_ns)
> return;
> - posix_acl_fix_xattr_userns(user_ns, &init_user_ns, mnt_userns, value,
> - size, false);
> + posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
> }
>
> /*
> diff --git a/fs/xattr.c b/fs/xattr.c
> index e8dd03e4561e..d60893b0056c 100644
> --- a/fs/xattr.c
> +++ b/fs/xattr.c
> @@ -282,13 +282,19 @@ __vfs_setxattr_locked(struct user_namespace *mnt_userns, struct dentry *dentry,
> }
> EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
>
> +static inline bool is_posix_acl_xattr(const char *name)
> +{
> + return (strcmp(name, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
> + (strcmp(name, XATTR_NAME_POSIX_ACL_DEFAULT) == 0);
> +}
> +
> int
> vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> - const char *name, const void *value, size_t size, int flags)
> + const char *name, void *value, size_t size, int flags)
> {
> struct inode *inode = dentry->d_inode;
> struct inode *delegated_inode = NULL;
> - const void *orig_value = value;
> + void *orig_value = value;
> int error;
>
> if (size && strcmp(name, XATTR_NAME_CAPS) == 0) {
> @@ -298,6 +304,9 @@ vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> size = error;
> }
>
> + if (size && is_posix_acl_xattr(name))
> + posix_acl_setxattr_idmapped_mnt(mnt_userns, inode, value, size);
> +
> retry_deleg:
> inode_lock(inode);
> error = __vfs_setxattr_locked(mnt_userns, dentry, name, value, size,
> @@ -431,7 +440,10 @@ vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> return ret;
> }
> nolsm:
> - return __vfs_getxattr(dentry, inode, name, value, size);
> + error = __vfs_getxattr(dentry, inode, name, value, size);
> + if (error > 0 && is_posix_acl_xattr(name))
> + posix_acl_getxattr_idmapped_mnt(mnt_userns, inode, value, size);
> + return error;
> }
> EXPORT_SYMBOL_GPL(vfs_getxattr);
>
> @@ -577,8 +589,7 @@ static void setxattr_convert(struct user_namespace *mnt_userns,
> if (ctx->size &&
> ((strcmp(ctx->kname->name, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
> (strcmp(ctx->kname->name, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)))
> - posix_acl_fix_xattr_from_user(mnt_userns, d_inode(d),
> - ctx->kvalue, ctx->size);
> + posix_acl_fix_xattr_from_user(ctx->kvalue, ctx->size);
> }
>
> int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> @@ -695,8 +706,7 @@ do_getxattr(struct user_namespace *mnt_userns, struct dentry *d,
> if (error > 0) {
> if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
> (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
> - posix_acl_fix_xattr_to_user(mnt_userns, d_inode(d),
> - ctx->kvalue, error);
> + posix_acl_fix_xattr_to_user(ctx->kvalue, error);
> if (ctx->size && copy_to_user(ctx->value, ctx->kvalue, error))
> error = -EFAULT;
> } else if (error == -ERANGE && ctx->size >= XATTR_SIZE_MAX) {
> diff --git a/include/linux/capability.h b/include/linux/capability.h
> index 65efb74c3585..c65c0d3c77d3 100644
> --- a/include/linux/capability.h
> +++ b/include/linux/capability.h
> @@ -276,6 +276,6 @@ int get_vfs_caps_from_disk(struct user_namespace *mnt_userns,
> struct cpu_vfs_cap_data *cpu_caps);
>
> int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry,
> - const void **ivalue, size_t size);
> + void **ivalue, size_t size);
>
> #endif /* !_LINUX_CAPABILITY_H */
> diff --git a/include/linux/posix_acl_xattr.h b/include/linux/posix_acl_xattr.h
> index 1766e1de6956..c4afeebcae32 100644
> --- a/include/linux/posix_acl_xattr.h
> +++ b/include/linux/posix_acl_xattr.h
> @@ -33,21 +33,29 @@ posix_acl_xattr_count(size_t size)
> }
>
> #ifdef CONFIG_FS_POSIX_ACL
> -void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns,
> - struct inode *inode,
> - void *value, size_t size);
> -void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns,
> - struct inode *inode,
> - void *value, size_t size);
> +void posix_acl_fix_xattr_from_user(void *value, size_t size);
> +void posix_acl_fix_xattr_to_user(void *value, size_t size);
> +void posix_acl_getxattr_idmapped_mnt(struct user_namespace *mnt_userns,
> + const struct inode *inode,
> + void *value, size_t size);
> +void posix_acl_setxattr_idmapped_mnt(struct user_namespace *mnt_userns,
> + const struct inode *inode,
> + void *value, size_t size);
> #else
> -static inline void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns,
> - struct inode *inode,
> - void *value, size_t size)
> +static inline void posix_acl_fix_xattr_from_user(void *value, size_t size)
> {
> }
> -static inline void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns,
> - struct inode *inode,
> - void *value, size_t size)
> +static inline void posix_acl_fix_xattr_to_user(void *value, size_t size)
> +{
> +}
> +void posix_acl_getxattr_idmapped_mnt(struct user_namespace *mnt_userns,
> + const struct inode *inode,
> + void *value, size_t size)
> +{
> +}
> +void posix_acl_setxattr_idmapped_mnt(struct user_namespace *mnt_userns,
> + const struct inode *inode,
> + void *value, size_t size)
> {
> }
> #endif
> diff --git a/include/linux/xattr.h b/include/linux/xattr.h
> index 4c379d23ec6e..979a9d3e5bfb 100644
> --- a/include/linux/xattr.h
> +++ b/include/linux/xattr.h
> @@ -61,7 +61,7 @@ int __vfs_setxattr_locked(struct user_namespace *, struct dentry *,
> const char *, const void *, size_t, int,
> struct inode **);
> int vfs_setxattr(struct user_namespace *, struct dentry *, const char *,
> - const void *, size_t, int);
> + void *, size_t, int);
> int __vfs_removexattr(struct user_namespace *, struct dentry *, const char *);
> int __vfs_removexattr_locked(struct user_namespace *, struct dentry *,
> const char *, struct inode **);
> diff --git a/security/commoncap.c b/security/commoncap.c
> index 5fc8986c3c77..47c9b1a4a8bb 100644
> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -538,7 +538,7 @@ static bool validheader(size_t size, const struct vfs_cap_data *cap)
> * Return: On success, return the new size; on error, return < 0.
> */
> int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry,
> - const void **ivalue, size_t size)
> + void **ivalue, size_t size)
> {
> struct vfs_ns_cap_data *nscap;
> uid_t nsrootid;
>
> base-commit: 88084a3df1672e131ddc1b4e39eeacfd39864acf
> --
> 2.34.1
>
