The current way of setting and getting posix acls through the generic
xattr interface is error prone and type unsafe. The vfs needs to
interpret and fixup posix acls before storing or reporting it to
userspace. Various hacks exist to make this work. The code is hard to
understand and difficult to maintain in it's current form. Instead of
making this work by hacking posix acls through xattr handlers we are
building a dedicated posix acl api around the get and set inode
operations. This removes a lot of hackiness and makes the codepaths
easier to maintain. A lot of background can be found in [1].
The current inode operation for getting posix acls takes an inode
argument but various filesystems (e.g., 9p, cifs, overlayfs) need access
to the dentry. In contrast to the ->set_acl() inode operation we cannot
simply extend ->get_acl() to take a dentry argument. The ->get_acl()
inode operation is called from:
acl_permission_check()
-> check_acl()
-> get_acl()
which is part of generic_permission() which in turn is part of
inode_permission(). Both generic_permission() and inode_permission() are
called in the ->permission() handler of various filesystems (e.g.,
overlayfs). So simply passing a dentry argument to ->get_acl() would
amount to also having to pass a dentry argument to ->permission(). We
should avoid this unnecessary change.
So instead of extending the existing inode operation rename it from
->get_acl() to ->get_inode_acl() and add a ->get_acl() method later that
passes a dentry argument and which filesystems that need access to the
dentry can implement instead of ->get_inode_acl(). Filesystems like cifs
which allow setting and getting posix acls but not using them for
permission checking during lookup can simply not implement
->get_inode_acl().
This is intended to be a non-functional change.
Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1]
Suggested-by/Inspired-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
The current way of setting and getting posix acls through the generic
xattr interface is error prone and type unsafe. The vfs needs to
interpret and fixup posix acls before storing or reporting it to
userspace. Various hacks exist to make this work. The code is hard to
understand and difficult to maintain in it's current form. Instead of
making this work by hacking posix acls through xattr handlers we are
building a dedicated posix acl api around the get and set inode
operations. This removes a lot of hackiness and makes the codepaths
easier to maintain. A lot of background can be found in [1].
Since some filesystem rely on the dentry being available to them when
setting posix acls (e.g., 9p and cifs) they cannot rely on set acl inode
operation. But since ->set_acl() is required in order to use the generic
posix acl xattr handlers filesystems that do not implement this inode
operation cannot use the handler and need to implement their own
dedicated posix acl handlers.
Update the ->set_acl() inode method to take a dentry argument. This
allows all filesystems to rely on ->set_acl().
As far as I can tell all codepaths can be switched to rely on the dentry
instead of just the inode. Note that the original motivation for passing
the dentry separate from the inode instead of just the dentry in the
xattr handlers was because of security modules that call
security_d_instantiate(). This hook is called during
d_instantiate_new(), d_add(), __d_instantiate_anon(), and
d_splice_alias() to initialize the inode's security context and possibly
to set security.* xattrs. Since this only affects security.* xattrs this
is completely irrelevant for posix acls.
Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1]
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
A while ago we introduced a dedicated vfs{g,u}id_t type in commit
1e5267cd08 ("mnt_idmapping: add vfs{g,u}id_t"). We already switched
over a good part of the VFS. Ultimately we will remove all legacy
idmapped mount helpers that operate only on k{g,u}id_t in favor of the
new type safe helpers that operate on vfs{g,u}id_t.
Cc: Seth Forshee (Digital Ocean) <sforshee@kernel.org>
Cc: Steve French <sfrench@samba.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Hyunchul Lee <hyc.lee@gmail.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
... in particular, there should never be a non-const pointers to
any file->f_path.
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steve French <stfrench@microsoft.com>
The issue happens in a specific path in smb_check_perm_dacl(). When
"id" and "uid" have the same value, the function simply jumps out of
the loop without decrementing the reference count of the object
"posix_acls", which is increased by get_acl() earlier. This may
result in memory leaks.
Fix it by decreasing the reference count of "posix_acls" before
jumping to label "check_access_bits".
Fixes: 777cad1604 ("ksmbd: remove select FS_POSIX_ACL in Kconfig")
Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.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>
Add buffer validation for SMB2_CREATE_CONTEXT.
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Reviewed-by: Ralph Boehme <slow@samba.org>
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Addresses-Coverity reported Control flow issues in sid_to_id()
/fs/ksmbd/smbacl.c: 277 in sid_to_id()
271
272 if (sidtype == SIDOWNER) {
273 kuid_t uid;
274 uid_t id;
275
276 id = le32_to_cpu(psid->sub_auth[psid->num_subauth - 1]);
>>> CID 1506810: Control flow issues (NO_EFFECT)
>>> This greater-than-or-equal-to-zero comparison of an unsigned value
>>> is always true. "id >= 0U".
277 if (id >= 0) {
278 /*
279 * Translate raw sid into kuid in the server's user
280 * namespace.
281 */
282 uid = make_kuid(&init_user_ns, id);
Addresses-Coverity: ("Control flow issues")
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
When ownership is changed we might in certain scenarios loose the
ability to alter the inode after we changed ownership. This can e.g.
happen when we are on an idmapped mount where uid 0 is mapped to uid
1000 and uid 1000 is mapped to uid 0.
A caller with fs*id 1000 will be able to create files as *id 1000 on
disk. They will also be able to change ownership of files owned by *id 0
to *id 1000 but they won't be able to change ownership in the other
direction. This means acl operations following notify_change() would
fail. Move the notify_change() call after the acls have been updated.
This guarantees that we don't end up with spurious "hash value diff"
warnings later on because we managed to change ownership but didn't
manage to alter acls.
Cc: Steve French <stfrench@microsoft.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Hyunchul Lee <hyc.lee@gmail.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
The sid_to_id() functions is relevant when changing ownership of
filesystem objects based on acl information. In this case we need to
first translate the relevant s*ids into k*ids in ksmbd's user namespace
and account for any idmapped mounts. Requesting a change in ownership
requires the inverse translation to be applied when we would report
ownership to userspace. So k*id_from_mnt() must be used here.
Cc: Steve French <stfrench@microsoft.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Hyunchul Lee <hyc.lee@gmail.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
It's not obvious why subauth 0 would be excluded from translation. This
would lead to wrong results whenever a non-identity idmapping is used.
Cc: Steve French <stfrench@microsoft.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Hyunchul Lee <hyc.lee@gmail.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
The ksmbd server performs translation of posix acls to smb acls.
Currently the translation is wrong since the idmapping of the mount is
used to map the ids into raw userspace ids but what is relevant is the
user namespace of ksmbd itself. The user namespace of ksmbd itself which
is the initial user namespace. The operation is similar to asking "What
*ids would a userspace process see given that k*id in the relevant user
namespace?". Before the final translation we need to apply the idmapping
of the mount in case any is used. Add two simple helpers for ksmbd.
Cc: Steve French <stfrench@microsoft.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Hyunchul Lee <hyc.lee@gmail.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
When creating new filesystem objects ksmbd translates between k*ids and
s*ids. For this it often uses struct smb_fattr and stashes the k*ids in
cf_uid and cf_gid. Let cf_uid and cf_gid always contain the final
information taking any potential idmapped mounts into account. When
finally translation cf_*id into s*ids translate them into the user
namespace of ksmbd since that is the relevant user namespace here.
Cc: Steve French <stfrench@microsoft.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Hyunchul Lee <hyc.lee@gmail.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
When commanding chmod and chown on cifs&ksmbd, ksmbd allows it without file
permissions check. There is code to check it in settattr_prepare.
Instead of setting the inode directly, update the mode and uid/gid
through notify_change.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
When there is no dacl in request, ksmbd send dacl that coverted by using
file permission. This patch don't set FILE DELETE and FILE_DELETE_CHILD
in access mask by default.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
ksmbd is forcing to turn on FS_POSIX_ACL in Kconfig to use vfs acl
functions(posix_acl_alloc, get_acl, set_posix_acl). OpenWRT and other
platform doesn't use acl and this config is disable by default in
kernel. This patch use IS_ENABLED() to know acl config is enable and use
acl function if it is enable.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Add two labels to fix memory leak in smb_inherit_dacl().
Reported-by: Coverity Scan <scan-admin@coverity.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Avoid calling mnt_user_ns() many time in
a function.
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christian Brauner <christian@brauner.io>
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
For user namespace support, call vfs functions
with struct user_namespace got from struct path.
This patch have been tested mannually as below.
Create an id-mapped mount using the mount-idmapped utility
(https://github.com/brauner/mount-idmapped).
$ mount-idmapped --map-mount b:1003:1002:1 /home/foo <EXPORT DIR>/foo
(the user, "foo" is 1003, and the user "bar" is 1002).
And mount the export directory using cifs with the user, "bar".
succeed to create/delete/stat/read/write files and directory in
the <EXPORT DIR>/foo. But fail with a bind mount for /home/foo.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
For user namespace support, we need to pass
struct user_namespace with struct dentry
to some functions. For reducing the number
of arguments, replace the struct dentry with
struct path in these functions.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reorder and document on-disk and netlink structures in headers.
This is a userspace ABI to communicate data between ksmbd and user IPC
daemon using netlink. This is added to track and cache user account DB
and share configuration info from userspace.
- KSMBD_EVENT_HEARTBEAT_REQUEST(ksmbd_heartbeat)
This event is to check whether user IPC daemon is alive. If user IPC
daemon is dead, ksmbd keep existing connection till disconnecting and
new connection will be denied.
- KSMBD_EVENT_STARTING_UP(ksmbd_startup_request)
This event is to receive the information that initializes the ksmbd
server from the user IPC daemon and to start the server. The global
section parameters are given from smb.conf as initialization
information.
- KSMBD_EVENT_SHUTTING_DOWN(ksmbd_shutdown_request)
This event is to shutdown ksmbd server.
- KSMBD_EVENT_LOGIN_REQUEST/RESPONSE(ksmbd_login_request/response)
This event is to get user account info to user IPC daemon.
- KSMBD_EVENT_SHARE_CONFIG_REQUEST/RESPONSE
(ksmbd_share_config_request/response)
This event is to get net share configuration info.
- KSMBD_EVENT_TREE_CONNECT_REQUEST/RESPONSE
(ksmbd_tree_connect_request/response)
This event is to get session and tree connect info.
- KSMBD_EVENT_TREE_DISCONNECT_REQUEST(ksmbd_tree_disconnect_request)
This event is to send tree disconnect info to user IPC daemon.
- KSMBD_EVENT_LOGOUT_REQUEST(ksmbd_logout_request)
This event is to send logout request to user IPC daemon.
- KSMBD_EVENT_RPC_REQUEST/RESPONSE(ksmbd_rpc_command)
This event is to make DCE/RPC request like srvsvc, wkssvc, lsarpc,
samr to be processed in userspace.
- KSMBD_EVENT_SPNEGO_AUTHEN_REQUEST/RESPONSE
(ksmbd_spnego_authen_request/response)
This event is to make kerberos authentication to be processed in
userspace.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Move fs/cifsd to fs/ksmbd and rename the remaining cifsd name to ksmbd.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
