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2021-06-29fs: move ramfs_aops to libfsChristoph Hellwig1-7/+1
Move the ramfs aops to libfs and reuse them for kernfs and configfs. Thosw two did not wire up ->set_page_dirty before and now get __set_page_dirty_no_writeback, which is the right one for no-writeback address_space usage. Drop the now unused exports of the libfs helpers only used for ramfs-style pagecache usage. Link: https://lkml.kernel.org/r/20210614061512.3966143-3-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-23Merge tag 'idmapped-mounts-v5.12' of ↵Linus Torvalds3-12/+22
git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux Pull idmapped mounts from Christian Brauner: "This introduces idmapped mounts which has been in the making for some time. Simply put, different mounts can expose the same file or directory with different ownership. This initial implementation comes with ports for fat, ext4 and with Christoph's port for xfs with more filesystems being actively worked on by independent people and maintainers. Idmapping mounts handle a wide range of long standing use-cases. Here are just a few: - Idmapped mounts make it possible to easily share files between multiple users or multiple machines especially in complex scenarios. For example, idmapped mounts will be used in the implementation of portable home directories in systemd-homed.service(8) where they allow users to move their home directory to an external storage device and use it on multiple computers where they are assigned different uids and gids. This effectively makes it possible to assign random uids and gids at login time. - It is possible to share files from the host with unprivileged containers without having to change ownership permanently through chown(2). - It is possible to idmap a container's rootfs and without having to mangle every file. For example, Chromebooks use it to share the user's Download folder with their unprivileged containers in their Linux subsystem. - It is possible to share files between containers with non-overlapping idmappings. - Filesystem that lack a proper concept of ownership such as fat can use idmapped mounts to implement discretionary access (DAC) permission checking. - They allow users to efficiently changing ownership on a per-mount basis without having to (recursively) chown(2) all files. In contrast to chown (2) changing ownership of large sets of files is instantenous with idmapped mounts. This is especially useful when ownership of a whole root filesystem of a virtual machine or container is changed. With idmapped mounts a single syscall mount_setattr syscall will be sufficient to change the ownership of all files. - Idmapped mounts always take the current ownership into account as idmappings specify what a given uid or gid is supposed to be mapped to. This contrasts with the chown(2) syscall which cannot by itself take the current ownership of the files it changes into account. It simply changes the ownership to the specified uid and gid. This is especially problematic when recursively chown(2)ing a large set of files which is commong with the aforementioned portable home directory and container and vm scenario. - Idmapped mounts allow to change ownership locally, restricting it to specific mounts, and temporarily as the ownership changes only apply as long as the mount exists. Several userspace projects have either already put up patches and pull-requests for this feature or will do so should you decide to pull this: - systemd: In a wide variety of scenarios but especially right away in their implementation of portable home directories. https://systemd.io/HOME_DIRECTORY/ - container runtimes: containerd, runC, LXD:To share data between host and unprivileged containers, unprivileged and privileged containers, etc. The pull request for idmapped mounts support in containerd, the default Kubernetes runtime is already up for quite a while now: https://github.com/containerd/containerd/pull/4734 - The virtio-fs developers and several users have expressed interest in using this feature with virtual machines once virtio-fs is ported. - ChromeOS: Sharing host-directories with unprivileged containers. I've tightly synced with all those projects and all of those listed here have also expressed their need/desire for this feature on the mailing list. For more info on how people use this there's a bunch of talks about this too. Here's just two recent ones: https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdf https://fosdem.org/2021/schedule/event/containers_idmap/ This comes with an extensive xfstests suite covering both ext4 and xfs: https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts It covers truncation, creation, opening, xattrs, vfscaps, setid execution, setgid inheritance and more both with idmapped and non-idmapped mounts. It already helped to discover an unrelated xfs setgid inheritance bug which has since been fixed in mainline. It will be sent for inclusion with the xfstests project should you decide to merge this. In order to support per-mount idmappings vfsmounts are marked with user namespaces. The idmapping of the user namespace will be used to map the ids of vfs objects when they are accessed through that mount. By default all vfsmounts are marked with the initial user namespace. The initial user namespace is used to indicate that a mount is not idmapped. All operations behave as before and this is verified in the testsuite. Based on prior discussions we want to attach the whole user namespace and not just a dedicated idmapping struct. This allows us to reuse all the helpers that already exist for dealing with idmappings instead of introducing a whole new range of helpers. In addition, if we decide in the future that we are confident enough to enable unprivileged users to setup idmapped mounts the permission checking can take into account whether the caller is privileged in the user namespace the mount is currently marked with. The user namespace the mount will be marked with can be specified by passing a file descriptor refering to the user namespace as an argument to the new mount_setattr() syscall together with the new MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern of extensibility. The following conditions must be met in order to create an idmapped mount: - The caller must currently have the CAP_SYS_ADMIN capability in the user namespace the underlying filesystem has been mounted in. - The underlying filesystem must support idmapped mounts. - The mount must not already be idmapped. This also implies that the idmapping of a mount cannot be altered once it has been idmapped. - The mount must be a detached/anonymous mount, i.e. it must have been created by calling open_tree() with the OPEN_TREE_CLONE flag and it must not already have been visible in the filesystem. The last two points guarantee easier semantics for userspace and the kernel and make the implementation significantly simpler. By default vfsmounts are marked with the initial user namespace and no behavioral or performance changes are observed. The manpage with a detailed description can be found here: https://git.kernel.org/brauner/man-pages/c/1d7b902e2875a1ff342e036a9f866a995640aea8 In order to support idmapped mounts, filesystems need to be changed and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The patches to convert individual filesystem are not very large or complicated overall as can be seen from the included fat, ext4, and xfs ports. Patches for other filesystems are actively worked on and will be sent out separately. The xfstestsuite can be used to verify that port has been done correctly. The mount_setattr() syscall is motivated independent of the idmapped mounts patches and it's been around since July 2019. One of the most valuable features of the new mount api is the ability to perform mounts based on file descriptors only. Together with the lookup restrictions available in the openat2() RESOLVE_* flag namespace which we added in v5.6 this is the first time we are close to hardened and race-free (e.g. symlinks) mounting and path resolution. While userspace has started porting to the new mount api to mount proper filesystems and create new bind-mounts it is currently not possible to change mount options of an already existing bind mount in the new mount api since the mount_setattr() syscall is missing. With the addition of the mount_setattr() syscall we remove this last restriction and userspace can now fully port to the new mount api, covering every use-case the old mount api could. We also add the crucial ability to recursively change mount options for a whole mount tree, both removing and adding mount options at the same time. This syscall has been requested multiple times by various people and projects. There is a simple tool available at https://github.com/brauner/mount-idmapped that allows to create idmapped mounts so people can play with this patch series. I'll add support for the regular mount binary should you decide to pull this in the following weeks: Here's an example to a simple idmapped mount of another user's home directory: u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt u1001@f2-vm:/$ ls -al /home/ubuntu/ total 28 drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 . drwxr-xr-x 4 root root 4096 Oct 28 04:00 .. -rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history -rw-r--r-- 1 ubuntu ubuntu 220 Feb 25 2020 .bash_logout -rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25 2020 .bashrc -rw-r--r-- 1 ubuntu ubuntu 807 Feb 25 2020 .profile -rw-r--r-- 1 ubuntu ubuntu 0 Oct 16 16:11 .sudo_as_admin_successful -rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo u1001@f2-vm:/$ ls -al /mnt/ total 28 drwxr-xr-x 2 u1001 u1001 4096 Oct 28 22:07 . drwxr-xr-x 29 root root 4096 Oct 28 22:01 .. -rw------- 1 u1001 u1001 3154 Oct 28 22:12 .bash_history -rw-r--r-- 1 u1001 u1001 220 Feb 25 2020 .bash_logout -rw-r--r-- 1 u1001 u1001 3771 Feb 25 2020 .bashrc -rw-r--r-- 1 u1001 u1001 807 Feb 25 2020 .profile -rw-r--r-- 1 u1001 u1001 0 Oct 16 16:11 .sudo_as_admin_successful -rw------- 1 u1001 u1001 1144 Oct 28 00:43 .viminfo u1001@f2-vm:/$ touch /mnt/my-file u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file u1001@f2-vm:/$ ls -al /mnt/my-file -rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file u1001@f2-vm:/$ ls -al /home/ubuntu/my-file -rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file u1001@f2-vm:/$ getfacl /mnt/my-file getfacl: Removing leading '/' from absolute path names # file: mnt/my-file # owner: u1001 # group: u1001 user::rw- user:u1001:rwx group::rw- mask::rwx other::r-- u1001@f2-vm:/$ getfacl /home/ubuntu/my-file getfacl: Removing leading '/' from absolute path names # file: home/ubuntu/my-file # owner: ubuntu # group: ubuntu user::rw- user:ubuntu:rwx group::rw- mask::rwx other::r--" * tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits) xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl xfs: support idmapped mounts ext4: support idmapped mounts fat: handle idmapped mounts tests: add mount_setattr() selftests fs: introduce MOUNT_ATTR_IDMAP fs: add mount_setattr() fs: add attr_flags_to_mnt_flags helper fs: split out functions to hold writers namespace: only take read lock in do_reconfigure_mnt() mount: make {lock,unlock}_mount_hash() static namespace: take lock_mount_hash() directly when changing flags nfs: do not export idmapped mounts overlayfs: do not mount on top of idmapped mounts ecryptfs: do not mount on top of idmapped mounts ima: handle idmapped mounts apparmor: handle idmapped mounts fs: make helpers idmap mount aware exec: handle idmapped mounts would_dump: handle idmapped mounts ...
2021-01-24fs: make helpers idmap mount awareChristian Brauner3-8/+16
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>
2021-01-24stat: handle idmapped mountsChristian Brauner1-1/+1
The generic_fillattr() helper fills in the basic attributes associated with an inode. Enable it to handle idmapped mounts. If the inode is accessed through an idmapped mount map it into the mount's user namespace before we store the uid and gid. 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/20210121131959.646623-12-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>
2021-01-24acl: handle idmapped mountsChristian Brauner1-0/+2
The posix acl permission checking helpers determine whether a caller is privileged over an inode according to the acls associated with the inode. Add helpers that make it possible to handle acls on idmapped mounts. The vfs and the filesystems targeted by this first iteration make use of posix_acl_fix_xattr_from_user() and posix_acl_fix_xattr_to_user() to translate basic posix access and default permissions such as the ACL_USER and ACL_GROUP type according to the initial user namespace (or the superblock's user namespace) to and from the caller's current user namespace. Adapt these two helpers to handle idmapped mounts whereby we either map from or into the mount's user namespace depending on in which direction we're translating. Similarly, cap_convert_nscap() is used by the vfs to translate user namespace and non-user namespace aware filesystem capabilities from the superblock's user namespace to the caller's user namespace. Enable it to handle idmapped mounts by accounting for the mount's user namespace. In addition the fileystems targeted in the first iteration of this patch series make use of the posix_acl_chmod() and, posix_acl_update_mode() helpers. Both helpers perform permission checks on the target inode. Let them handle idmapped mounts. These two helpers are called when posix acls are set by the respective filesystems to handle this case we extend the ->set() method to take an additional user namespace argument to pass the mount's user namespace down. Link: https://lore.kernel.org/r/20210121131959.646623-9-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-24attr: handle idmapped mountsChristian Brauner1-2/+2
When file attributes are changed most filesystems rely on the setattr_prepare(), setattr_copy(), and notify_change() helpers for initialization and permission checking. Let them handle idmapped mounts. 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 mounts. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Helpers that perform checks on the ia_uid and ia_gid fields in struct iattr assume that ia_uid and ia_gid are intended values and have already been mapped correctly at the userspace-kernelspace boundary as we already do today. 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/20210121131959.646623-8-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-24namei: make permission helpers idmapped mount awareChristian Brauner1-1/+1
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>
2021-01-21kernfs: wire up ->splice_read and ->splice_writeChristoph Hellwig1-0/+2
Wire up the splice_read and splice_write methods to the default helpers using ->read_iter and ->write_iter now that those are implemented for kernfs. This restores support to use splice and sendfile on kernfs files. Fixes: 36e2c7421f02 ("fs: don't allow splice read/write without explicit ops") Reported-by: Siddharth Gupta <sidgup@codeaurora.org> Tested-by: Siddharth Gupta <sidgup@codeaurora.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20210120204631.274206-4-hch@lst.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-21kernfs: implement ->write_iterChristoph Hellwig1-18/+10
Switch kernfs to implement the write_iter method instead of plain old write to prepare to supporting splice and sendfile again. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20210120204631.274206-3-hch@lst.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-21kernfs: implement ->read_iterChristoph Hellwig1-23/+12
Switch kernfs to implement the read_iter method instead of plain old read to prepare to supporting splice and sendfile again. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20210120204631.274206-2-hch@lst.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-09fs/kernfs: remove the double check of dentry->inodeHui Su1-2/+1
In both kernfs_node_from_dentry() and in kernfs_dentry_node(), we will check the dentry->inode is NULL or not, which is superfluous. So remove the check in kernfs_node_from_dentry(). Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Hui Su <sh_def@163.com> Link: https://lore.kernel.org/r/20201113132143.GA119541@rlk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-09kernfs: bring names in comments in line with codeWillem de Bruijn1-1/+1
Fix two stragglers in the comments of the below rename operation. Fixes: adc5e8b58f48 ("kernfs: drop s_ prefix from kernfs_node members") Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Willem de Bruijn <willemb@google.com> Link: https://lore.kernel.org/r/20201015185726.1386868-1-willemdebruijn.kernel@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-27fsnotify: pass dir and inode arguments to fsnotify()Amir Goldstein1-2/+3
The arguments of fsnotify() are overloaded and mean different things for different event types. Replace the to_tell argument with separate arguments @dir and @inode, because we may be sending to both dir and child. Using the @data argument to pass the child is not enough, because dirent events pass this argument (for audit), but we do not report to child. Document the new fsnotify() function argumenets. Link: https://lore.kernel.org/r/20200722125849.17418-7-amir73il@gmail.com Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz>
2020-07-27fsnotify: create helper fsnotify_inode()Amir Goldstein1-4/+2
Simple helper to consolidate biolerplate code. Link: https://lore.kernel.org/r/20200722125849.17418-5-amir73il@gmail.com Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz>
2020-07-27fsnotify: send event to parent and child with single callbackAmir Goldstein1-4/+6
Instead of calling fsnotify() twice, once with parent inode and once with child inode, if event should be sent to parent inode, send it with both parent and child inodes marks in object type iterator and call the backend handle_event() callback only once. The parent inode is assigned to the standard "inode" iterator type and the child inode is assigned to the special "child" iterator type. In that case, the bit FS_EVENT_ON_CHILD will be set in the event mask, the dir argument to handle_event will be the parent inode, the file_name argument to handle_event is non NULL and refers to the name of the child and the child inode can be accessed with fsnotify_data_inode(). This will allow fanotify to make decisions based on child or parent's ignored mask. For example, when a parent is interested in a specific event on its children, but a specific child wishes to ignore this event, the event will not be reported. This is not what happens with current code, but according to man page, it is the expected behavior. Link: https://lore.kernel.org/r/20200716084230.30611-15-amir73il@gmail.com Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz>
2020-07-15kernfs: do not call fsnotify() with name without a parentAmir Goldstein1-1/+1
When creating an FS_MODIFY event on inode itself (not on parent) the file_name argument should be NULL. The change to send a non NULL name to inode itself was done on purpuse as part of another commit, as Tejun writes: "...While at it, supply the target file name to fsnotify() from kernfs_node->name.". But this is wrong practice and inconsistent with inotify behavior when watching a single file. When a child is being watched (as opposed to the parent directory) the inotify event should contain the watch descriptor, but not the file name. Fixes: df6a58c5c5aa ("kernfs: don't depend on d_find_any_alias()...") Link: https://lore.kernel.org/r/20200708111156.24659-5-amir73il@gmail.com Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz>
2020-06-09mmap locking API: convert mmap_sem commentsMichel Lespinasse1-2/+2
Convert comments that reference mmap_sem to reference mmap_lock instead. [akpm@linux-foundation.org: fix up linux-next leftovers] [akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil] [akpm@linux-foundation.org: more linux-next fixups, per Michel] Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-23kernfs: Change kernfs_node lockdep name to "kn->active"Waiman Long1-1/+1
The kernfs_node lockdep tracking is being done on kn->active, the active reference count. The other reference count (kn->count) is not tracked by lockdep. So change the lockdep name to reflect what it is tracking. Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20200402171056.27871-1-longman@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-16kernfs: Add option to enable user xattrsDaniel Xu2-0/+91
User extended attributes are useful as metadata storage for kernfs consumers like cgroups. Especially in the case of cgroups, it is useful to have a central metadata store that multiple processes/services can use to coordinate actions. A concrete example is for userspace out of memory killers. We want to let delegated cgroup subtree owners (running as non-root) to be able to say "please avoid killing this cgroup". This is especially important for desktop linux as delegated subtrees owners are less likely to run as root. This patch introduces a new flag, KERNFS_ROOT_SUPPORT_USER_XATTR, that lets kernfs consumers enable user xattr support. An initial limit of 128 entries or 128KB -- whichever is hit first -- is placed per cgroup because xattrs come from kernel memory and we don't want to let unprivileged users accidentally eat up too much kernel memory. Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Acked-by: Chris Down <chris@chrisdown.name> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2020-03-16kernfs: Add removed_size out param for simple_xattr_setDaniel Xu1-1/+1
This helps set up size accounting in the next commit. Without this out param, it's difficult to find out the removed xattr size without taking a lock for longer and walking the xattr linked list twice. Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Acked-by: Chris Down <chris@chrisdown.name> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2020-02-05Merge branch 'imm.timestamp' of ↵Linus Torvalds1-3/+3
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs timestamp updates from Al Viro: "More 64bit timestamp work" * 'imm.timestamp' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: kernfs: don't bother with timestamp truncation fs: Do not overload update_time fs: Delete timespec64_trunc() fs: ubifs: Eliminate timespec64_trunc() usage fs: ceph: Delete timespec64_trunc() usage fs: cifs: Delete usage of timespec64_trunc fs: fat: Eliminate timespec64_trunc() usage utimes: Clamp the timestamps in notify_change()
2020-01-14fs/kernfs/dir.c: Clean code by removing always true conditionMateusz Nosek1-1/+1
Previously there was an additional check if variable pos is not null. However, this check happens after entering while loop and only then, which can happen only if pos is not null. Therefore the additional check is redundant and can be removed. Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20191230191628.21099-1-mateusznosek0@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-12-08kernfs: don't bother with timestamp truncationAl Viro1-3/+3
kernfs users are not going to have limited range or granularity anyway. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-12-06Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfsLinus Torvalds1-1/+1
Pull vfs d_inode/d_flags memory ordering fixes from Al Viro: "Fallout from tree-wide audit for ->d_inode/->d_flags barriers use. Basically, the problem is that negative pinned dentries require careful treatment - unless ->d_lock is locked or parent is held at least shared, another thread can make them positive right under us. Most of the uses turned out to be safe - the main surprises as far as filesystems are concerned were - race in dget_parent() fastpath, that might end up with the caller observing the returned dentry _negative_, due to insufficient barriers. It is positive in memory, but we could end up seeing the wrong value of ->d_inode in CPU cache. Fixed. - manual checks that result of lookup_one_len_unlocked() is positive (and rejection of negatives). Again, insufficient barriers (we might end up with inconsistent observed values of ->d_inode and ->d_flags). Fixed by switching to a new primitive that does the checks itself and returns ERR_PTR(-ENOENT) instead of a negative dentry. That way we get rid of boilerplate converting negatives into ERR_PTR(-ENOENT) in the callers and have a single place to deal with the barrier-related mess - inside fs/namei.c rather than in every caller out there. The guts of pathname resolution *do* need to be careful - the race found by Ritesh is real, as well as several similar races. Fortunately, it turns out that we can take care of that with fairly local changes in there. The tree-wide audit had not been fun, and I hate the idea of repeating it. I think the right approach would be to annotate the places where we are _not_ guaranteed ->d_inode/->d_flags stability and have sparse catch regressions. But I'm still not sure what would be the least invasive way of doing that and it's clearly the next cycle fodder" * 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: fs/namei.c: fix missing barriers when checking positivity fix dget_parent() fastpath race new helper: lookup_positive_unlocked() fs/namei.c: pull positivity check into follow_managed()
2019-11-26Merge branch 'locking-core-for-linus' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: "The main changes in this cycle were: - A comprehensive rewrite of the robust/PI futex code's exit handling to fix various exit races. (Thomas Gleixner et al) - Rework the generic REFCOUNT_FULL implementation using atomic_fetch_* operations so that the performance impact of the cmpxchg() loops is mitigated for common refcount operations. With these performance improvements the generic implementation of refcount_t should be good enough for everybody - and this got confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and REFCOUNT_FULL entirely, leaving the generic implementation enabled unconditionally. (Will Deacon) - Other misc changes, fixes, cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) lkdtm: Remove references to CONFIG_REFCOUNT_FULL locking/refcount: Remove unused 'refcount_error_report()' function locking/refcount: Consolidate implementations of refcount_t locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions locking/refcount: Move saturation warnings out of line locking/refcount: Improve performance of generic REFCOUNT_FULL code locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header locking/refcount: Remove unused refcount_*_checked() variants locking/refcount: Ensure integer operands are treated as signed locking/refcount: Define constants for saturation and max refcount values futex: Prevent exit livelock futex: Provide distinct return value when owner is exiting futex: Add mutex around futex exit futex: Provide state handling for exec() as well futex: Sanitize exit state handling futex: Mark the begin of futex exit explicitly futex: Set task::futex_state to DEAD right after handling futex exit futex: Split futex_mm_release() for exit/exec exit/exec: Seperate mm_release() futex: Replace PF_EXITPIDONE with a state ...
2019-11-15new helper: lookup_positive_unlocked()Al Viro1-1/+1
Most of the callers of lookup_one_len_unlocked() treat negatives are ERR_PTR(-ENOENT). Provide a helper that would do just that. Note that a pinned positive dentry remains positive - it's ->d_inode is stable, etc.; a pinned _negative_ dentry can become positive at any point as long as you are not holding its parent at least shared. So using lookup_one_len_unlocked() needs to be careful; lookup_positive_unlocked() is safer and that's what the callers end up open-coding anyway. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-11-12kernfs: use 64bit inos if ino_t is 64bitTejun Heo2-16/+33
Each kernfs_node is identified with a 64bit ID. The low 32bit is exposed as ino and the high gen. While this already allows using inos as keys by looking up with wildcard generation number of 0, it's adding unnecessary complications for 64bit ino archs which can directly use kernfs_node IDs as inos to uniquely identify each cgroup instance. This patch exposes IDs directly as inos on 64bit ino archs. The conversion is mostly straight-forward. * 32bit ino archs behave the same as before. 64bit ino archs now use the whole 64bit ID as ino and the generation number is fixed at 1. * 64bit inos still use the same idr allocator which gurantees that the lower 32bits identify the current live instance uniquely and the high 32bits are incremented whenever the low bits wrap. As the upper 32bits are no longer used as gen and we don't wanna start ino allocation with 33rd bit set, the initial value for highbits allocation is changed to 0 on 64bit ino archs. * blktrace exposes two 32bit numbers - (INO,GEN) pair - to identify the issuing cgroup. Userland builds FILEID_INO32_GEN fids from these numbers to look up the cgroups. To remain compatible with the behavior, always output (LOW32,HIGH32) which will be constructed back to the original 64bit ID by __kernfs_fh_to_dentry(). Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Namhyung Kim <namhyung@kernel.org>
2019-11-12kernfs: implement custom exportfs ops and fid typeTejun Heo1-16/+61
The current kernfs exportfs implementation uses the generic_fh_*() helpers and FILEID_INO32_GEN[_PARENT] which limits ino to 32bits. Let's implement custom exportfs operations and fid type to remove the restriction. * FILEID_KERNFS is a single u64 value whose content is kernfs_node->id. This is the only native fid type. * For backward compatibility with blk_log_action() path which exposes (ino,gen) pairs which userland assembles into FILEID_INO32_GEN keys, combine the generic keys into 64bit IDs in the same order. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Namhyung Kim <namhyung@kernel.org>
2019-11-12kernfs: combine ino/id lookup functions into kernfs_find_and_get_node_by_id()Tejun Heo3-30/+15
kernfs_find_and_get_node_by_ino() looks the kernfs_node matching the specified ino. On top of that, kernfs_get_node_by_id() and kernfs_fh_get_inode() implement full ID matching by testing the rest of ID. On surface, confusingly, the two are slightly different in that the latter uses 0 gen as wildcard while the former doesn't - does it mean that the latter can't uniquely identify inodes w/ 0 gen? In practice, this is a distinction without a difference because generation number starts at 1. There are no actual IDs with 0 gen, so it can always safely used as wildcard. Let's simplify the code by renaming kernfs_find_and_get_node_by_ino() to kernfs_find_and_get_node_by_id(), moving all lookup logics into it, and removing now unnecessary kernfs_get_node_by_id(). Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-11-12kernfs: convert kernfs_node->id from union kernfs_node_id to u64Tejun Heo4-13/+12
kernfs_node->id is currently a union kernfs_node_id which represents either a 32bit (ino, gen) pair or u64 value. I can't see much value in the usage of the union - all that's needed is a 64bit ID which the current code is already limited to. Using a union makes the code unnecessarily complicated and prevents using 64bit ino without adding practical benefits. This patch drops union kernfs_node_id and makes kernfs_node->id a u64. ino is stored in the lower 32bits and gen upper. Accessors - kernfs[_id]_ino() and kernfs[_id]_gen() - are added to retrieve the ino and gen. This simplifies ID handling less cumbersome and will allow using 64bit inos on supported archs. This patch doesn't make any functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Alexei Starovoitov <ast@kernel.org>
2019-11-12kernfs: kernfs_find_and_get_node_by_ino() should only look up activated nodesTejun Heo1-1/+7
kernfs node can be created in two separate steps - allocation and activation. This is used to make kernfs nodes visible only after the internal states attached to the node are fully initialized. kernfs_find_and_get_node_by_id() currently allows lookups of nodes which aren't activated yet and thus can expose nodes are which are still being prepped by kernfs users. Fix it by disallowing lookups of nodes which aren't activated yet. kernfs_find_and_get_node_by_ino() Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Namhyung Kim <namhyung@kernel.org>
2019-11-12kernfs: use dumber locking for kernfs_find_and_get_node_by_ino()Tejun Heo2-46/+10
kernfs_find_and_get_node_by_ino() uses RCU protection. It's currently a bit buggy because it can look up a node which hasn't been activated yet and thus may end up exposing a node that the kernfs user is still prepping. While it can be fixed by pushing it further in the current direction, it's already complicated and isn't clear whether the complexity is justified. The main use of kernfs_find_and_get_node_by_ino() is for exportfs operations. They aren't super hot and all the follow-up operations (e.g. mapping to path) use normal locking anyway. Let's switch to a dumber locking scheme and protect the lookup with kernfs_idr_lock. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Namhyung Kim <namhyung@kernel.org>
2019-11-12kernfs: fix ino wrap-around detectionTejun Heo1-3/+2
When the 32bit ino wraps around, kernfs increments the generation number to distinguish reused ino instances. The wrap-around detection tests whether the allocated ino is lower than what the cursor but the cursor is pointing to the next ino to allocate so the condition never triggers. Fix it by remembering the last ino and comparing against that. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Fixes: 4a3ef68acacf ("kernfs: implement i_generation") Cc: Namhyung Kim <namhyung@kernel.org> Cc: stable@vger.kernel.org # v4.14+
2019-10-09locking/lockdep: Remove unused @nested argument from lock_release()Qian Cai1-2/+2
Since the following commit: b4adfe8e05f1 ("locking/lockdep: Remove unused argument in __lock_release") @nested is no longer used in lock_release(), so remove it from all lock_release() calls and friends. Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will@kernel.org> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: alexander.levin@microsoft.com Cc: daniel@iogearbox.net Cc: davem@davemloft.net Cc: dri-devel@lists.freedesktop.org Cc: duyuyang@gmail.com Cc: gregkh@linuxfoundation.org Cc: hannes@cmpxchg.org Cc: intel-gfx@lists.freedesktop.org Cc: jack@suse.com Cc: jlbec@evilplan.or Cc: joonas.lahtinen@linux.intel.com Cc: joseph.qi@linux.alibaba.com Cc: jslaby@suse.com Cc: juri.lelli@redhat.com Cc: maarten.lankhorst@linux.intel.com Cc: mark@fasheh.com Cc: mhocko@kernel.org Cc: mripard@kernel.org Cc: ocfs2-devel@oss.oracle.com Cc: rodrigo.vivi@intel.com Cc: sean@poorly.run Cc: st@kernel.org Cc: tj@kernel.org Cc: tytso@mit.edu Cc: vdavydov.dev@gmail.com Cc: vincent.guittot@linaro.org Cc: viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/1568909380-32199-1-git-send-email-cai@lca.pw Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-19Merge tag 'y2038-vfs' of ↵Linus Torvalds1-4/+3
git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground Pull y2038 vfs updates from Arnd Bergmann: "Add inode timestamp clamping. This series from Deepa Dinamani adds a per-superblock minimum/maximum timestamp limit for a file system, and clamps timestamps as they are written, to avoid random behavior from integer overflow as well as having different time stamps on disk vs in memory. At mount time, a warning is now printed for any file system that can represent current timestamps but not future timestamps more than 30 years into the future, similar to the arbitrary 30 year limit that was added to settimeofday(). This was picked as a compromise to warn users to migrate to other file systems (e.g. ext4 instead of ext3) when they need the file system to survive beyond 2038 (or similar limits in other file systems), but not get in the way of normal usage" * tag 'y2038-vfs' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground: ext4: Reduce ext4 timestamp warnings isofs: Initialize filesystem timestamp ranges pstore: fs superblock limits fs: omfs: Initialize filesystem timestamp ranges fs: hpfs: Initialize filesystem timestamp ranges fs: ceph: Initialize filesystem timestamp ranges fs: sysv: Initialize filesystem timestamp ranges fs: affs: Initialize filesystem timestamp ranges fs: fat: Initialize filesystem timestamp ranges fs: cifs: Initialize filesystem timestamp ranges fs: nfs: Initialize filesystem timestamp ranges ext4: Initialize timestamps limits 9p: Fill min and max timestamps in sb fs: Fill in max and min timestamps in superblock utimes: Clamp the timestamps before update mount: Add mount warning for impending timestamp expiry timestamp_truncate: Replace users of timespec64_trunc vfs: Add timestamp_truncate() api vfs: Add file timestamp range support
2019-08-30timestamp_truncate: Replace users of timespec64_truncDeepa Dinamani1-4/+3
Update the inode timestamp updates to use timestamp_truncate() instead of timespec64_trunc(). The change was mostly generated by the following coccinelle script. virtual context virtual patch @r1 depends on patch forall@ struct inode *inode; identifier i_xtime =~ "^i_[acm]time$"; expression e; @@ inode->i_xtime = - timespec64_trunc( + timestamp_truncate( ..., - e); + inode); Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Jeff Layton <jlayton@kernel.org> Cc: adrian.hunter@intel.com Cc: dedekind1@gmail.com Cc: gregkh@linuxfoundation.org Cc: hch@lst.de Cc: jaegeuk@kernel.org Cc: jlbec@evilplan.org Cc: richard@nod.at Cc: tj@kernel.org Cc: yuchao0@huawei.com Cc: linux-f2fs-devel@lists.sourceforge.net Cc: linux-ntfs-dev@lists.sourceforge.net Cc: linux-mtd@lists.infradead.org
2019-07-25fs: kernfs: Fix possible null-pointer dereferences in ↵Jia-Ju Bai1-2/+4
kernfs_path_from_node_locked() In kernfs_path_from_node_locked(), there is an if statement on line 147 to check whether buf is NULL: if (buf) When buf is NULL, it is used on line 151: len += strlcpy(buf + len, parent_str, ...) and line 158: len += strlcpy(buf + len, "/", ...) and line 160: len += strlcpy(buf + len, kn->name, ...) Thus, possible null-pointer dereferences may occur. To fix these possible bugs, buf is checked before being used. If it is NULL, -EINVAL is returned. These bugs are found by a static analysis tool STCheck written by us. Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> Link: https://lore.kernel.org/r/20190724022242.27505-1-baijiaju1990@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-07-25kernfs: fix potential null pointer dereferencePeng Wang1-2/+1
Get root safely after kn is ensureed to be not null. Signed-off-by: Peng Wang <rocking@whu.edu.cn> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20190708151611.13242-1-rocking@whu.edu.cn Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428Thomas Gleixner6-12/+6
Based on 1 normalized pattern(s): this file is released under the gplv2 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 68 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Armijn Hemel <armijn@tjaldur.nl> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190531190114.292346262@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21treewide: Add SPDX license identifier - Makefile/KconfigThomas Gleixner2-0/+2
Add SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any form 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>
2019-05-07Merge branch 'work.dcache' of ↵Linus Torvalds1-2/+4
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull misc dcache updates from Al Viro: "Most of this pile is putting name length into struct name_snapshot and making use of it. The beginning of this series ("ovl_lookup_real_one(): don't bother with strlen()") ought to have been split in two (separate switch of name_snapshot to struct qstr from overlayfs reaping the trivial benefits of that), but I wanted to avoid a rebase - by the time I'd spotted that it was (a) in -next and (b) close to 5.1-final ;-/" * 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: audit_compare_dname_path(): switch to const struct qstr * audit_update_watch(): switch to const struct qstr * inotify_handle_event(): don't bother with strlen() fsnotify: switch send_to_group() and ->handle_event to const struct qstr * fsnotify(): switch to passing const struct qstr * for file_name switch fsnotify_move() to passing const struct qstr * for old_name ovl_lookup_real_one(): don't bother with strlen() sysv: bury the broken "quietly truncate the long filenames" logics nsfs: unobfuscate unexport d_alloc_pseudo()
2019-05-07Merge tag 'selinux-pr-20190507' of ↵Linus Torvalds4-116/+82
git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux Pull selinux updates from Paul Moore: "We've got a few SELinux patches for the v5.2 merge window, the highlights are below: - Add LSM hooks, and the SELinux implementation, for proper labeling of kernfs. While we are only including the SELinux implementation here, the rest of the LSM folks have given the hooks a thumbs-up. - Update the SELinux mdp (Make Dummy Policy) script to actually work on a modern system. - Disallow userspace to change the LSM credentials via /proc/self/attr when the task's credentials are already overridden. The change was made in procfs because all the LSM folks agreed this was the Right Thing To Do and duplicating it across each LSM was going to be annoying" * tag 'selinux-pr-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: proc: prevent changes to overridden credentials selinux: Check address length before reading address family kernfs: fix xattr name handling in LSM helpers MAINTAINERS: update SELinux file patterns selinux: avoid uninitialized variable warning selinux: remove useless assignments LSM: lsm_hooks.h - fix missing colon in docstring selinux: Make selinux_kernfs_init_security static kernfs: initialize security of newly created nodes selinux: implement the kernfs_init_security hook LSM: add new hook for kernfs node initialization kernfs: use simple_xattrs for security attributes selinux: try security xattr after genfs for kernfs filesystems kernfs: do not alloc iattrs in kernfs_xattr_get kernfs: clean up struct kernfs_iattrs scripts/selinux: fix build selinux: use kernel linux/socket.h for genheaders and mdp scripts/selinux: modernize mdp
2019-04-26fsnotify(): switch to passing const struct qstr * for file_nameAl Viro1-2/+4
Note that in fnsotify_move() and fsnotify_link() we are guaranteed that dentry->d_name won't change during the fsnotify() evaluation (by having the parent directory locked exclusive), so we don't need to fetch dentry->d_name.name in the callers. In fsnotify_dirent() the same stability of dentry->d_name is also true, but it's a bit more convoluted - there is one callchain (devpts_pty_new() -> fsnotify_create() -> fsnotify_dirent()) where the parent is _not_ locked, but on devpts ->d_name of everything is unchanging; it has neither explicit nor implicit renames. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-04-25kernfs: fix barrier usage in __kernfs_new_node()Andrea Parri1-3/+2
smp_mb__before_atomic() can not be applied to atomic_set(). Remove the barrier and rely on RELEASE synchronization. Fixes: ba16b2846a8c6 ("kernfs: add an API to get kernfs node from inode number") Cc: stable@vger.kernel.org Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-04kernfs: fix xattr name handling in LSM helpersOndrej Mosnacek1-41/+21
The implementation of kernfs_security_xattr_*() helpers reuses the kernfs_node_xattr_*() functions, which take the suffix of the xattr name and extract full xattr name from it using xattr_full_name(). However, this function relies on the fact that the suffix passed to xattr handlers from VFS is always constructed from the full name by just incerementing the pointer. This doesn't necessarily hold for the callers of kernfs_security_xattr_*(), so their usage will easily lead to out-of-bounds access. Fix this by moving the xattr name reconstruction to the VFS xattr handlers and replacing the kernfs_security_xattr_*() helpers with more general kernfs_xattr_*() helpers that take full xattr name and allow accessing all kernfs node's xattrs. Reported-by: kernel test robot <rong.a.chen@intel.com> Fixes: b230d5aba2d1 ("LSM: add new hook for kernfs node initialization") Fixes: ec882da5cda9 ("selinux: implement the kernfs_init_security hook") Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-03-20kernfs: initialize security of newly created nodesOndrej Mosnacek1-2/+9
Use the new security_kernfs_init_security() hook to allow LSMs to possibly assign a non-default security context to a newly created kernfs node based on the attributes of the new node and also its parent node. This fixes an issue with cgroupfs under SELinux, where newly created cgroup subdirectories/files would not inherit its parent's context if it had been set explicitly to a non-default value (other than the genfs context specified by the policy). This can be reproduced as follows (on Fedora/RHEL): # mkdir /sys/fs/cgroup/unified/test # # Need permissive to change the label under Fedora policy: # setenforce 0 # chcon -t container_file_t /sys/fs/cgroup/unified/test # ls -lZ /sys/fs/cgroup/unified total 0 -r--r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:06 cgroup.controllers -rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:06 cgroup.max.depth -rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:06 cgroup.max.descendants -rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:06 cgroup.procs -r--r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:06 cgroup.stat -rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:06 cgroup.subtree_control -rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:06 cgroup.threads drwxr-xr-x. 2 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:06 init.scope drwxr-xr-x. 26 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:21 system.slice drwxr-xr-x. 3 root root system_u:object_r:container_file_t:s0 0 Jan 29 03:15 test drwxr-xr-x. 3 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:06 user.slice # mkdir /sys/fs/cgroup/unified/test/subdir Actual result: # ls -ldZ /sys/fs/cgroup/unified/test/subdir drwxr-xr-x. 2 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:15 /sys/fs/cgroup/unified/test/subdir Expected result: # ls -ldZ /sys/fs/cgroup/unified/test/subdir drwxr-xr-x. 2 root root unconfined_u:object_r:container_file_t:s0 0 Jan 29 03:15 /sys/fs/cgroup/unified/test/subdir Link: https://github.com/SELinuxProject/selinux-kernel/issues/39 Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-03-20LSM: add new hook for kernfs node initializationOndrej Mosnacek1-9/+39
This patch introduces a new security hook that is intended for initializing the security data for newly created kernfs nodes, which provide a way of storing a non-default security context, but need to operate independently from mounts (and therefore may not have an associated inode at the moment of creation). The main motivation is to allow kernfs nodes to inherit the context of the parent under SELinux, similar to the behavior of security_inode_init_security(). Other LSMs may implement their own logic for handling the creation of new nodes. This patch also adds helper functions to <linux/kernfs.h> for getting/setting security xattrs of a kernfs node so that LSMs hooks are able to do their job. Other important attributes should be accessible direcly in the kernfs_node fields (in case there is need for more, then new helpers should be added to kernfs.h along with the patch that needs them). Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> [PM: more manual merge fixes] Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-03-20kernfs: use simple_xattrs for security attributesOndrej Mosnacek3-58/+2
Replace the special handling of security xattrs with simple_xattrs, as is already done for the trusted xattrs. This simplifies the code and allows LSMs to use more than just a single xattr to do their business. Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> [PM: manual merge fixes] Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-03-20kernfs: do not alloc iattrs in kernfs_xattr_getOndrej Mosnacek1-4/+14
This is a read-only operation, so we can simply return -ENODATA if kn->iattr is NULL. Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> [PM: minor merge fixes] Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-03-20kernfs: clean up struct kernfs_iattrsOndrej Mosnacek4-36/+31
Right now, kernfs_iattrs embeds the whole struct iattr, even though it doesn't really use half of its fields... This both leads to wasting space and makes the code look awkward. Let's just list the few fields we need directly in struct kernfs_iattrs. Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> [PM: merged a number of chunks manually due to fuzz] Signed-off-by: Paul Moore <paul@paul-moore.com>