kernel.git/fs/nsfs.c, branch linux-6.15.y

Merge tag 'vfs-6.15-rc1.nsfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-03-24T18:38:12Z

Pull vfs nsfs updates from Christian Brauner: "This contains non-urgent fixes for nsfs to validate ioctls before performing any relevant operations. We alredy did this for a few other filesystems last cycle" * tag 'vfs-6.15-rc1.nsfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: selftests/nsfs: add ioctl validation tests nsfs: validate ioctls

nsfs: remove d_op->d_delete

2025-02-24T10:30:35Z

Nsfs only deals with unhashed dentries and there's currently no way for them to become hashed. So remove d_op->d_delete. Signed-off-by: Christian Brauner

nsfs: validate ioctls

2025-02-20T08:13:49Z

Nsfs supports extensible and non-extensible ioctls. Validate both types to prevent confusion. Link: https://lore.kernel.org/r/20250219-work-nsfs-v1-1-21128d73c5e8@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner

fs: lockless mntns lookup for nsfs

2025-01-09T15:58:52Z

We already made the rbtree lookup lockless for the simple lookup case. However, walking the list of mount namespaces via nsfs still happens with taking the read lock blocking concurrent additions of new mount namespaces pointlessly. Plus, such additions are rare anyway so allow lockless lookup of the previous and next mount namespace by keeping a separate list. This also allows to make some things simpler in the code. Link: https://lore.kernel.org/r/20241213-work-mount-rbtree-lockless-v3-5-6e3cdaf9b280@kernel.org Reviewed-by: Jeff Layton Suggested-by: Peter Zijlstra Signed-off-by: Christian Brauner

[tree-wide] finally take no_llseek out

2024-09-27T15:18:43Z

no_llseek had been defined to NULL two years ago, in commit 868941b14441 ("fs: remove no_llseek") To quote that commit, At -rc1 we'll need do a mechanical removal of no_llseek - git grep -l -w no_llseek | grep -v porting.rst | while read i; do sed -i '/\/d' $i done would do it. Unfortunately, that hadn't been done. Linus, could you do that now, so that we could finally put that thing to rest? All instances are of the form .llseek = no_llseek, so it's obviously safe. Signed-off-by: Al Viro Signed-off-by: Linus Torvalds

nsfs: iterate through mount namespaces

2024-08-09T10:46:59Z

It is already possible to list mounts in other mount namespaces and to retrieve namespace file descriptors without having to go through procfs by deriving them from pidfds. Augment these abilities by adding the ability to retrieve information about a mount namespace via NS_MNT_GET_INFO. This will return the mount namespace id and the number of mounts currently in the mount namespace. The number of mounts can be used to size the buffer that needs to be used for listmount() and is in general useful without having to actually iterate through all the mounts. The structure is extensible. And add the ability to iterate through all mount namespaces over which the caller holds privilege returning the file descriptor for the next or previous mount namespace. To retrieve a mount namespace the caller must be privileged wrt to it's owning user namespace. This means that PID 1 on the host can list all mounts in all mount namespaces or that a container can list all mounts of its nested containers. Optionally pass a structure for NS_MNT_GET_INFO with NS_MNT_GET_{PREV,NEXT} to retrieve information about the mount namespace in one go. Both ioctls can be implemented for other namespace types easily. Together with recent api additions this means one can iterate through all mounts in all mount namespaces without ever touching procfs. Link: https://lore.kernel.org/r/20240719-work-mount-namespace-v1-5-834113cab0d2@kernel.org Reviewed-by: Josef Bacik Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner

nsfs: use cleanup guard

2024-07-18T07:50:08Z

Ensure that rcu read lock is given up before returning. Link: https://lore.kernel.org/r/20240716-elixier-fliesen-1ab342151a61@brauner Fixes: ca567df74a28 ("nsfs: add pid translation ioctls") Reported-by: syzbot+a3e82ae343b26b4d2335@syzkaller.appspotmail.com Signed-off-by: Christian Brauner

Merge tag 'vfs-6.11.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-07-15T19:34:01Z

Pull pidfs updates from Christian Brauner: "This contains work to make it possible to derive namespace file descriptors from pidfd file descriptors. Right now it is already possible to use a pidfd with setns() to atomically change multiple namespaces at the same time. In other words, it is possible to switch to the namespace context of a process using a pidfd. There is no need to first open namespace file descriptors via procfs. The work included here is an extension of these abilities by allowing to open namespace file descriptors using a pidfd. This means it is now possible to interact with namespaces without ever touching procfs. To this end a new set of ioctls() on pidfds is introduced covering all supported namespace types" * tag 'vfs-6.11.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: pidfs: allow retrieval of namespace file descriptors nsfs: add open_namespace() nsproxy: add helper to go from arbitrary namespace to ns_common nsproxy: add a cleanup helper for nsproxy file: add take_fd() cleanup helper

Merge tag 'vfs-6.11.nsfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-07-15T19:27:39Z

Pull namespace-fs updates from Christian Brauner: "This adds ioctls allowing to translate PIDs between PID namespaces. The motivating use-case comes from LXCFS which is a tiny fuse filesystem used to virtualize various aspects of procfs. LXCFS is run on the host. The files and directories it creates can be bind-mounted by e.g. a container at startup and mounted over the various procfs files the container wishes to have virtualized. When e.g. a read request for uptime is received, LXCFS will receive the pid of the reader. In order to virtualize the corresponding read, LXCFS needs to know the pid of the init process of the reader's pid namespace. In order to do this, LXCFS first needs to fork() two helper processes. The first helper process setns() to the readers pid namespace. The second helper process is needed to create a process that is a proper member of the pid namespace. The second helper process then creates a ucred message with ucred.pid set to 1 and sends it back to LXCFS. The kernel will translate the ucred.pid field to the corresponding pid number in LXCFS's pid namespace. This way LXCFS can learn the init pid number of the reader's pid namespace and can go on to virtualize. Since these two forks() are costly LXCFS maintains an init pid cache that caches a given pid for a fixed amount of time. The cache is pruned during new read requests. However, even with the cache the hit of the two forks() is singificant when a very large number of containers are running. So this adds a simple set of ioctls that let's a caller translate PIDs from and into a given PID namespace. This significantly improves performance with a very simple change. To protect against races pidfds can be used to check whether the process is still valid" * tag 'vfs-6.11.nsfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: nsfs: add pid translation ioctls

nsfs: add open_namespace()

2024-06-28T08:37:29Z

and call it from open_related_ns(). Link: https://lore.kernel.org/r/20240627-work-pidfs-v1-3-7e9ab6cc3bb1@kernel.org Reviewed-by: Jeff Layton Reviewed-by: Josef Bacik Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner