kernel/linux.git/fs/kernfs, branch v6.18.22

Merge tag 'vfs-6.18-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-09-29T16:03:07+00:00

Pull misc vfs updates from Christian Brauner: "This contains the usual selections of misc updates for this cycle. Features: - Add "initramfs_options" parameter to set initramfs mount options. This allows to add specific mount options to the rootfs to e.g., limit the memory size - Add RWF_NOSIGNAL flag for pwritev2() Add RWF_NOSIGNAL flag for pwritev2. This flag prevents the SIGPIPE signal from being raised when writing on disconnected pipes or sockets. The flag is handled directly by the pipe filesystem and converted to the existing MSG_NOSIGNAL flag for sockets - Allow to pass pid namespace as procfs mount option Ever since the introduction of pid namespaces, procfs has had very implicit behaviour surrounding them (the pidns used by a procfs mount is auto-selected based on the mounting process's active pidns, and the pidns itself is basically hidden once the mount has been constructed) This implicit behaviour has historically meant that userspace was required to do some special dances in order to configure the pidns of a procfs mount as desired. Examples include: * In order to bypass the mnt_too_revealing() check, Kubernetes creates a procfs mount from an empty pidns so that user namespaced containers can be nested (without this, the nested containers would fail to mount procfs) But this requires forking off a helper process because you cannot just one-shot this using mount(2) * Container runtimes in general need to fork into a container before configuring its mounts, which can lead to security issues in the case of shared-pidns containers (a privileged process in the pidns can interact with your container runtime process) While SUID_DUMP_DISABLE and user namespaces make this less of an issue, the strict need for this due to a minor uAPI wart is kind of unfortunate Things would be much easier if there was a way for userspace to just specify the pidns they want. So this pull request contains changes to implement a new "pidns" argument which can be set using fsconfig(2): fsconfig(procfd, FSCONFIG_SET_FD, "pidns", NULL, nsfd); fsconfig(procfd, FSCONFIG_SET_STRING, "pidns", "/proc/self/ns/pid", 0); or classic mount(2) / mount(8): // mount -t proc -o pidns=/proc/self/ns/pid proc /tmp/proc mount("proc", "/tmp/proc", "proc", MS_..., "pidns=/proc/self/ns/pid"); Cleanups: - Remove the last references to EXPORT_OP_ASYNC_LOCK - Make file_remove_privs_flags() static - Remove redundant __GFP_NOWARN when GFP_NOWAIT is used - Use try_cmpxchg() in start_dir_add() - Use try_cmpxchg() in sb_init_done_wq() - Replace offsetof() with struct_size() in ioctl_file_dedupe_range() - Remove vfs_ioctl() export - Replace rwlock() with spinlock in epoll code as rwlock causes priority inversion on preempt rt kernels - Make ns_entries in fs/proc/namespaces const - Use a switch() statement() in init_special_inode() just like we do in may_open() - Use struct_size() in dir_add() in the initramfs code - Use str_plural() in rd_load_image() - Replace strcpy() with strscpy() in find_link() - Rename generic_delete_inode() to inode_just_drop() and generic_drop_inode() to inode_generic_drop() - Remove unused arguments from fcntl_{g,s}et_rw_hint() Fixes: - Document @name parameter for name_contains_dotdot() helper - Fix spelling mistake - Always return zero from replace_fd() instead of the file descriptor number - Limit the size for copy_file_range() in compat mode to prevent a signed overflow - Fix debugfs mount options not being applied - Verify the inode mode when loading it from disk in minixfs - Verify the inode mode when loading it from disk in cramfs - Don't trigger automounts with RESOLVE_NO_XDEV If openat2() was called with RESOLVE_NO_XDEV it didn't traverse through automounts, but could still trigger them - Add FL_RECLAIM flag to show_fl_flags() macro so it appears in tracepoints - Fix unused variable warning in rd_load_image() on s390 - Make INITRAMFS_PRESERVE_MTIME depend on BLK_DEV_INITRD - Use ns_capable_noaudit() when determining net sysctl permissions - Don't call path_put() under namespace semaphore in listmount() and statmount()" * tag 'vfs-6.18-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (38 commits) fcntl: trim arguments listmount: don't call path_put() under namespace semaphore statmount: don't call path_put() under namespace semaphore pid: use ns_capable_noaudit() when determining net sysctl permissions fs: rename generic_delete_inode() and generic_drop_inode() init: INITRAMFS_PRESERVE_MTIME should depend on BLK_DEV_INITRD initramfs: Replace strcpy() with strscpy() in find_link() initrd: Use str_plural() in rd_load_image() initramfs: Use struct_size() helper to improve dir_add() initrd: Fix unused variable warning in rd_load_image() on s390 fs: use the switch statement in init_special_inode() fs/proc/namespaces: make ns_entries const filelock: add FL_RECLAIM to show_fl_flags() macro eventpoll: Replace rwlock with spinlock selftests/proc: add tests for new pidns APIs procfs: add "pidns" mount option pidns: move is-ancestor logic to helper openat2: don't trigger automounts with RESOLVE_NO_XDEV namei: move cross-device check to __traverse_mounts namei: remove LOOKUP_NO_XDEV check from handle_mounts ...

fs: rename generic_delete_inode() and generic_drop_inode()

2025-09-15T14:09:42+00:00

generic_delete_inode() is rather misleading for what the routine is doing. inode_just_drop() should be much clearer. The new naming is inconsistent with generic_drop_inode(), so rename that one as well with inode_ as the suffix. No functional changes. Signed-off-by: Mateusz Guzik Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

kernfs: Fix UAF in polling when open file is released

2025-09-06T18:11:27+00:00

A use-after-free (UAF) vulnerability was identified in the PSI (Pressure Stall Information) monitoring mechanism: BUG: KASAN: slab-use-after-free in psi_trigger_poll+0x3c/0x140 Read of size 8 at addr ffff3de3d50bd308 by task systemd/1 psi_trigger_poll+0x3c/0x140 cgroup_pressure_poll+0x70/0xa0 cgroup_file_poll+0x8c/0x100 kernfs_fop_poll+0x11c/0x1c0 ep_item_poll.isra.0+0x188/0x2c0 Allocated by task 1: cgroup_file_open+0x88/0x388 kernfs_fop_open+0x73c/0xaf0 do_dentry_open+0x5fc/0x1200 vfs_open+0xa0/0x3f0 do_open+0x7e8/0xd08 path_openat+0x2fc/0x6b0 do_filp_open+0x174/0x368 Freed by task 8462: cgroup_file_release+0x130/0x1f8 kernfs_drain_open_files+0x17c/0x440 kernfs_drain+0x2dc/0x360 kernfs_show+0x1b8/0x288 cgroup_file_show+0x150/0x268 cgroup_pressure_write+0x1dc/0x340 cgroup_file_write+0x274/0x548 Reproduction Steps: 1. Open test/cpu.pressure and establish epoll monitoring 2. Disable monitoring: echo 0 > test/cgroup.pressure 3. Re-enable monitoring: echo 1 > test/cgroup.pressure The race condition occurs because: 1. When cgroup.pressure is disabled (echo 0 > cgroup.pressure), it: - Releases PSI triggers via cgroup_file_release() - Frees of->priv through kernfs_drain_open_files() 2. While epoll still holds reference to the file and continues polling 3. Re-enabling (echo 1 > cgroup.pressure) accesses freed of->priv epolling disable/enable cgroup.pressure fd=open(cpu.pressure) while(1) ... epoll_wait kernfs_fop_poll kernfs_get_active = true echo 0 > cgroup.pressure ... cgroup_file_show kernfs_show // inactive kn kernfs_drain_open_files cft->release(of); kfree(ctx); ... kernfs_get_active = false echo 1 > cgroup.pressure kernfs_show kernfs_activate_one(kn); kernfs_fop_poll kernfs_get_active = true cgroup_file_poll psi_trigger_poll // UAF ... end: close(fd) To address this issue, introduce kernfs_get_active_of() for kernfs open files to obtain active references. This function will fail if the open file has been released. Replace kernfs_get_active() with kernfs_get_active_of() to prevent further operations on released file descriptors. Fixes: 34f26a15611a ("sched/psi: Per-cgroup PSI accounting disable/re-enable interface") Cc: stable Reported-by: Zhang Zhaotian Signed-off-by: Chen Ridong Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20250822070715.1565236-2-chenridong@huaweicloud.com Signed-off-by: Greg Kroah-Hartman

kernfs: don't fail listing extended attributes

2025-08-19T11:51:28+00:00

Userspace doesn't expect a failure to list extended attributes: $ ls -lA /sys/ ls: /sys/: No data available ls: /sys/kernel: No data available ls: /sys/power: No data available ls: /sys/class: No data available ls: /sys/devices: No data available ls: /sys/dev: No data available ls: /sys/hypervisor: No data available ls: /sys/fs: No data available ls: /sys/bus: No data available ls: /sys/firmware: No data available ls: /sys/block: No data available ls: /sys/module: No data available total 0 drwxr-xr-x 2 root root 0 Jan 1 1970 block drwxr-xr-x 52 root root 0 Jan 1 1970 bus drwxr-xr-x 88 root root 0 Jan 1 1970 class drwxr-xr-x 4 root root 0 Jan 1 1970 dev drwxr-xr-x 11 root root 0 Jan 1 1970 devices drwxr-xr-x 3 root root 0 Jan 1 1970 firmware drwxr-xr-x 10 root root 0 Jan 1 1970 fs drwxr-xr-x 2 root root 0 Jul 2 09:43 hypervisor drwxr-xr-x 14 root root 0 Jan 1 1970 kernel drwxr-xr-x 251 root root 0 Jan 1 1970 module drwxr-xr-x 3 root root 0 Jul 2 09:43 power Fix it by simply reporting success when no extended attributes are available instead of reporting ENODATA. Link: https://lore.kernel.org/78b13bcdae82ade95e88f315682966051f461dde.camel@linaro.org Fixes: d1f4e9026007 ("kernfs: remove iattr_mutex") # mainline only Reported-by: André Draszik Link: https://lore.kernel.org/20250819-ahndung-abgaben-524a535f8101@brauner Signed-off-by: Christian Brauner

Merge tag 'bpf-next-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2025-07-30T16:58:50+00:00

Pull bpf updates from Alexei Starovoitov: - Remove usermode driver (UMD) framework (Thomas Weißschuh) - Introduce Strongly Connected Component (SCC) in the verifier to detect loops and refine register liveness (Eduard Zingerman) - Allow 'void *' cast using bpf_rdonly_cast() and corresponding '__arg_untrusted' for global function parameters (Eduard Zingerman) - Improve precision for BPF_ADD and BPF_SUB operations in the verifier (Harishankar Vishwanathan) - Teach the verifier that constant pointer to a map cannot be NULL (Ihor Solodrai) - Introduce BPF streams for error reporting of various conditions detected by BPF runtime (Kumar Kartikeya Dwivedi) - Teach the verifier to insert runtime speculation barrier (lfence on x86) to mitigate speculative execution instead of rejecting the programs (Luis Gerhorst) - Various improvements for 'veristat' (Mykyta Yatsenko) - For CONFIG_DEBUG_KERNEL config warn on internal verifier errors to improve bug detection by syzbot (Paul Chaignon) - Support BPF private stack on arm64 (Puranjay Mohan) - Introduce bpf_cgroup_read_xattr() kfunc to read xattr of cgroup's node (Song Liu) - Introduce kfuncs for read-only string opreations (Viktor Malik) - Implement show_fdinfo() for bpf_links (Tao Chen) - Reduce verifier's stack consumption (Yonghong Song) - Implement mprog API for cgroup-bpf programs (Yonghong Song) * tag 'bpf-next-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (192 commits) selftests/bpf: Migrate fexit_noreturns case into tracing_failure test suite selftests/bpf: Add selftest for attaching tracing programs to functions in deny list bpf: Add log for attaching tracing programs to functions in deny list bpf: Show precise rejected function when attaching fexit/fmod_ret to __noreturn functions bpf: Fix various typos in verifier.c comments bpf: Add third round of bounds deduction selftests/bpf: Test invariants on JSLT crossing sign selftests/bpf: Test cross-sign 64bits range refinement selftests/bpf: Update reg_bound range refinement logic bpf: Improve bounds when s64 crosses sign boundary bpf: Simplify bounds refinement from s32 selftests/bpf: Enable private stack tests for arm64 bpf, arm64: JIT support for private stack bpf: Move bpf_jit_get_prog_name() to core.c bpf, arm64: Fix fp initialization for exception boundary umd: Remove usermode driver framework bpf/preload: Don't select USERMODE_DRIVER selftests/bpf: Fix test dynptr/test_dynptr_memset_xdp_chunks failure selftests/bpf: Fix test dynptr/test_dynptr_copy_xdp failure selftests/bpf: Increase xdp data size for arm64 64K page size ...

Merge tag 'vfs-6.17-rc1.bpf' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-07-28T21:42:31+00:00

Pull vfs bpf updates from Christian Brauner: "These changes allow bpf to read extended attributes from cgroupfs. This is useful in redirecting AF_UNIX socket connections based on cgroup membership of the socket. One use-case is the ability to implement log namespaces in systemd so services and containers are redirected to different journals" * tag 'vfs-6.17-rc1.bpf' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: selftests/kernfs: test xattr retrieval selftests/bpf: Add tests for bpf_cgroup_read_xattr bpf: Mark cgroup_subsys_state->cgroup RCU safe bpf: Introduce bpf_cgroup_read_xattr to read xattr of cgroup's node kernfs: remove iattr_mutex

kernfs: remove iattr_mutex

2025-07-02T12:18:20+00:00

All allocations of struct kernfs_iattrs are serialized through a global mutex. Simply do a racy allocation and let the first one win. I bet most callers are under inode->i_rwsem anyway and it wouldn't be needed but let's not require that. Acked-by: Greg Kroah-Hartman Acked-by: Tejun Heo Signed-off-by: Song Liu Link: https://lore.kernel.org/20250623063854.1896364-2-song@kernel.org Signed-off-by: Christian Brauner

kernfs: remove iattr_mutex

2025-06-23T11:03:12+00:00

new helper: set_default_d_op()

2025-06-11T02:21:16+00:00

... to be used instead of manually assigning to ->s_d_op. All in-tree filesystem converted (and field itself is renamed, so any out-of-tree ones in need of conversion will be caught by compiler). Reviewed-by: Christian Brauner Signed-off-by: Al Viro

Merge tag 'driver-core-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core

2025-05-29T16:11:39+00:00

Pull driver core updates from Greg KH: "Here are the driver core / kernfs changes for 6.16-rc1. Not a huge number of changes this development cycle, here's the summary of what is included in here: - kernfs locking tweaks, pushing some global locks down into a per-fs image lock - rust driver core and pci device bindings added for new features. - sysfs const work for bin_attributes. The final churn of switching away from and removing the transitional struct members, "read_new", "write_new" and "bin_attrs_new" will come after the merge window to avoid unnecesary merge conflicts. - auxbus device creation helpers added - fauxbus fix for creating sysfs files after the probe completed properly - other tiny updates for driver core things. All of these have been in linux-next for over a week with no reported issues" * tag 'driver-core-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core: kernfs: Relax constraint in draining guard Documentation: embargoed-hardware-issues.rst: Remove myself drivers: hv: fix up const issue with vmbus_chan_bin_attrs firmware_loader: use SHA-256 library API instead of crypto_shash API docs: debugfs: do not recommend debugfs_remove_recursive PM: wakeup: Do not expose 4 device wakeup source APIs kernfs: switch global kernfs_rename_lock to per-fs lock kernfs: switch global kernfs_idr_lock to per-fs lock driver core: auxiliary bus: Fix IS_ERR() vs NULL mixup in __devm_auxiliary_device_create() sysfs: constify attribute_group::bin_attrs sysfs: constify bin_attribute argument of bin_attribute::read/write() software node: Correct a OOB check in software_node_get_reference_args() devres: simplify devm_kstrdup() using devm_kmemdup() platform: replace magic number with macro PLATFORM_DEVID_NONE component: do not try to unbind unbound components driver core: auxiliary bus: add device creation helpers driver core: faux: Add sysfs groups after probing