linux/include
Christian Brauner cdf930a009
fs: support FD_FAILFS_ROOT in fchdir()
Add a new file descriptor sentinel FD_FAILFS_ROOT following
FD_PIDFS_ROOT and FD_NSFS_ROOT and teach fchdir() to accept it. A
process calling fchdir(FD_FAILFS_ROOT) moves its working directory
into failfs. Every AT_FDCWD-relative lookup afterwards fails with
EOPNOTSUPP including "." and ".." and getcwd() reports the working
directory as unreachable from the process root by returning a path
prefixed with "(unreachable)". Lookups relative to explicit directory
file descriptors are unaffected.

The sentinel is the only way in. No privilege or gating is required.
Setting the working directory to a directory in which every operation
fails grants nothing and loses nothing that closing file descriptors
couldn't lose. An unlinked working directory behaves the same way today
modulo errno. The working directory also plays no role in confining ".."
resolution so no boundary is weakened.

Link: https://patch.msgid.link/20260724-work-failfs-v2-2-485dabbae185@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
2026-07-27 17:17:59 +02:00
..
acpi ACPICA: Define acpi_ut_safe_strncpy() as strscpy_pad() alias 2026-07-01 12:29:24 +02:00
asm-generic mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
clocksource
crypto Networking changes for 7.2. 2026-06-17 08:17:00 +01:00
cxl cxl/region: Introduce devm_cxl_probe_mem() 2026-06-12 13:47:30 -07:00
drm drm/amd/display: Force PWM backlight on Lenovo Legion 5 15ARH05 2026-07-17 17:41:15 -04:00
dt-bindings SoC fixes for 7.2 2026-07-17 08:52:09 -07:00
hyperv
keys keys: Pin request_key_auth payload in instantiate paths 2026-06-15 15:19:13 +03:00
kunit linux_kselftest-kunit-7.2-rc1 2026-06-16 16:33:57 +05:30
kvm Merge branch kvm-arm64/vgic-v5-PPI-fixes into kvmarm-master/next 2026-06-12 09:08:31 +01:00
linux BPF fixes: 2026-07-17 12:55:24 -07:00
math-emu
media media: v4l2-fwnode: Fix subdev owner overwritten in v4l2_async_register_subdev_sensor() 2026-06-05 10:28:03 +03:00
memory
misc
net sctp: fix auth_hmacs array size in struct sctp_cookie 2026-07-17 12:27:53 +02:00
pcmcia Replace <linux/mod_devicetable.h> by more specific <linux/device-id/*.h> (headers) 2026-07-03 07:38:16 +02:00
ras
rdma RDMA v7.2 merge window 2026-06-18 08:16:21 -07:00
rv rv: Prevent task migration while handling per-CPU events 2026-06-03 12:33:25 +02:00
scsi scsi: core: wake eh reliably when using scsi_schedule_eh 2026-07-12 22:21:22 -04:00
soc soc/tegra: pmc: Fixes for v7.2 2026-07-10 14:40:52 +02:00
sound Replace <linux/mod_devicetable.h> by more specific <linux/device-id/*.h> (headers) 2026-07-03 07:38:16 +02:00
target
trace This adds support for manual client session reset in CephFS, allowing 2026-06-26 16:15:53 -07:00
uapi fs: support FD_FAILFS_ROOT in fchdir() 2026-07-27 17:17:59 +02:00
ufs Merge branch 7.1/scsi-fixes into 7.2/scsi-staging 2026-06-15 21:01:30 -04:00
vdso futex: Provide infrastructure to plug the non contended robust futex unlock race 2026-06-03 11:38:52 +02:00
video
xen xen: Replace __ASSEMBLY__ with __ASSEMBLER__ in header files 2026-07-01 09:49:52 +02:00
Kbuild