p9fs: Fix creating files with restrictive permissions
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Authored by arichardson on Sat, Apr 18, 5:58 AM.

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Reviewers

markj
kib

Group Reviewers

cheri

Commits

rG40d59ee35dc1: p9fs: Fix creating files with restrictive permissions

Summary

When a file is created via p9fs with restrictive permissions (like 000),
the 9P TCREATE request successfully creates and natively opens the file,
returning an open, writable file descriptor. Previously, p9fs would
attempt a subsequent TOPEN. That TOPEN would fail with EACCES due to the
restrictive mode, leaving a 0-byte file and causing operations like 'mv'
to abort.

We now preserve the writable descriptor returned by TCREATE so that the
subsequent VOP_OPEN can use it directly, avoiding the failing TOPEN.
Additionally, p9fs_compatible_mode now appropriately isolates the base
access intent when matching fids, preventing extended flags from
breaking the match.

A test case for this behavior has been submitted to pjdfstest:
https://github.com/pjd/pjdfstest/pull/87

Resolves: https://github.com/CTSRD-CHERI/cheribsd/issues/2617

Diff Detail

Repository

rG FreeBSD src repository

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Tests Not Applicable

Event Timeline

arichardson created this revision.Sat, Apr 18, 5:58 AM

Herald added a subscriber: imp. · View Herald TranscriptSat, Apr 18, 5:58 AM

arichardson requested review of this revision.Sat, Apr 18, 5:58 AM

Herald added a reviewer: cheri. · View Herald TranscriptSat, Apr 18, 5:58 AM

Harbormaster completed remote builds in B72315: Diff 175817.Sat, Apr 18, 5:58 AM

arichardson added a parent revision: D56492: p9fs: Move UMA zone initialization to VFS module lifecycle.Sat, Apr 18, 6:01 AM

markj accepted this revision as: markj.Tue, Apr 21, 1:04 PM

This revision is now accepted and ready to land.Tue, Apr 21, 1:04 PM

jhb added a subscriber: jhb.Tue, Apr 21, 6:55 PM

jhb added inline comments.

sys/fs/p9fs/p9fs_subr.c
284	An old bug perhaps, but what about O_EXEC? Hmm, seems that isn't handled elsewhere either (e.g. in p9fs_uflags_mode() over in p9fs_vnops.c), so not anything trivial to try to handle here.