linux/include
Christian Brauner 5222470b2f
nsfs: support file handles
A while ago we added support for file handles to pidfs so pidfds can be
encoded and decoded as file handles. Userspace has adopted this quickly
and it's proven very useful. Implement file handles for namespaces as
well.

A process is not always able to open /proc/self/ns/. That requires
procfs to be mounted and for /proc/self/ or /proc/self/ns/ to not be
overmounted. However, userspace can always derive a namespace fd from
a pidfd. And that always works for a task's own namespace.

There's no need to introduce unnecessary behavioral differences between
/proc/self/ns/ fds, pidfd-derived namespace fds, and file-handle-derived
namespace fds. So namespace file handles are always decodable if the
caller is located in the namespace the file handle refers to.

This also allows a task to e.g., store a set of file handles to its
namespaces in a file on-disk so it can verify when it gets rexeced that
they're still valid and so on. This is akin to the pidfd use-case.

Or just plainly for namespace comparison reasons where a file handle to
the task's own namespace can be easily compared against others.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-09-19 14:26:16 +02:00
..
acpi mailbox/pcc: support mailbox management of the shared buffer 2025-08-07 23:49:56 -05:00
asm-generic Deferred unwind changes for 6.17 2025-08-01 09:46:24 -07:00
clocksource
crypto This push fixes a regression that breaks hmac(sha3-224-s390). 2025-08-09 07:26:19 +03:00
cxl
drm drm/gpuvm: fix various typos in .c and .h gpuvm file 2025-08-25 21:48:50 +02:00
dt-bindings Pin control changes for v6.17 2025-08-02 12:07:09 -07:00
hyperv
keys
kunit linux_kselftest-kunit-6.17-rc1 2025-07-29 12:43:10 -07:00
kvm KVM/arm64 changes for 6.17, round #1 2025-07-29 12:27:40 -04:00
linux nsfs: support file handles 2025-09-19 14:26:16 +02:00
math-emu
media
memory
misc
net ns: add to_<type>_ns() to respective headers 2025-09-19 14:26:16 +02:00
pcmcia
ras
rdma
rv
scsi
soc This is the usual collection of primarily clk driver updates. The big part of 2025-07-31 13:36:27 -07:00
sound ASoC: Fixes for v6.17 2025-08-21 09:02:28 +02:00
target
trace tracing changes for 6.17 2025-08-01 10:29:36 -07:00
uapi nsfs: support file handles 2025-09-19 14:26:16 +02:00
ufs
vdso
video
xen Significant patch series in this pull request: 2025-08-03 16:23:09 -07:00
Kbuild