linux/tools/testing
Christian Brauner d943e68edc
selftests/filesystems: test O_TMPFILE creation on idmapped mounts
Add a regression test for the fsuidgid_has_mapping() check in
vfs_tmpfile().  It idmaps a detached tmpfs mount so that the
caller-visible id range [0, 10000) maps onto the on-disk range
[10000, 20000) and checks that:

  - a caller whose fsuid/fsgid fall outside that range cannot create an
    O_TMPFILE through the mount and gets -EOVERFLOW instead of an inode
    owned by (uid_t)-1;

  - a mapped caller can create an O_TMPFILE, link it into the namespace,
    and the ownership round-trips through the mount idmap: it is reported
    as 0 through the mount and stored as 10000 on the underlying tmpfs.

The test runs entirely as root and uses setfsuid()/setfsgid() to become
the unmapped caller, so it needs no helper user.  The layer directory is
world-writable so that an unmapped caller still clears the directory
permission check and reaches the fsuidgid_has_mapping() test.

Link: https://patch.msgid.link/20260615-work-idmapped-tmpfile-v1-2-754a94d81f83@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
History 2026-07-01 15:26:18 +02:00
..
crypto/chacha20-s390 crypto: drbg - Fold include/crypto/drbg.h into crypto/drbg.c 2026-05-07 16:09:59 +08:00
cxl Merge branch 'for-7.2/cxl-type2-attach-region' into cxl-for-next 2026-06-12 13:47:53 -07:00
fault-injection failcmd: make failcmd.sh executable 2024-09-01 20:43:32 -07:00
ktest ktest: Add logfile to failure directory 2026-04-20 15:23:13 -04:00
kunit kunit:tool: Don't write to stdout when it should be disabled 2026-06-07 20:10:30 -06:00
memblock liveupdate: updates for 7.2-rc1 2026-06-21 09:46:14 -07:00
nvdimm tools/testing/nvdimm: Use per-DIMM device handle 2025-11-03 16:47:13 -06:00
radix-tree MAINTAINERS: update Liam's email address 2026-04-27 05:54:25 -07:00
rbtree lib/interval_tree: add test case for span iteration 2025-03-17 12:17:01 -07:00
scatterlist mm: remove nth_page() 2025-09-21 14:22:10 -07:00
selftests selftests/filesystems: test O_TMPFILE creation on idmapped mounts 2026-07-01 15:26:18 +02:00
shared mm/slab: improve kmem_cache_alloc_bulk 2026-06-03 18:20:43 +02:00
vma mm/vma: eliminate mmap_action->error_hook, introduce error_override 2026-06-04 14:45:00 -07:00
vsock vsock/test: add MSG_PEEK after partial recv test 2026-04-16 19:34:22 -07:00