ima: don't measure/appraise files on configfs

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IMA measurement of a configfs file causes process_measurement() to hold
iint->mutex while performing a kernel_read() to hash it, which re-enters
configfs's own file locking (buffer->mutex, frag_sem).

Separately, opening any file with O_TRUNC now causes ima_file_truncate()
to take iint->mutex to reset the cached action flags, while sb_writers is
already held for that mount.

When a configfs-backed nvmet namespace is involved, these two independent
lock chains combine into a cycle:

iint->mutex -> configfs locks -> subsys->lock -> sb_writers -> iint->mutex

Add configfs to the builtin don't measure/appraise rules, similarly to
other pseudo file systems, so IMA never takes iint->mutex for configfs
file in the first place.

Reported-by: syzbot+448c2e24b1ceff13ed2a@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/6a77c7cd.b50370da.49fe0.0031.GAE@google.com/
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Frederick Lawler <fred@cloudflare.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

...

This commit is contained in:

Frederick Lawler 2026-08-19 18:45:23 -05:00 • committed by Mimi Zohar

parent ab84c31441

commit 8e22ce504f

2 changed files with 9 additions and 1 deletions

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3

Documentation/ABI/testing/ima_policy

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7

security/integrity/ima/ima_policy.c

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