From abc02e5602f7bf9bbae1e8999570a2ad5114578c Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Tue, 11 Jun 2024 15:36:46 -0400 Subject: NFSD: Support write delegations in LAYOUTGET I noticed LAYOUTGET(LAYOUTIOMODE4_RW) returning NFS4ERR_ACCESS unexpectedly. The NFS client had created a file with mode 0444, and the server had returned a write delegation on the OPEN(CREATE). The client was requesting a RW layout using the write delegation stateid so that it could flush file modifications. Creating a read-only file does not seem to be problematic for NFSv4.1 without pNFS, so I began looking at NFSD's implementation of LAYOUTGET. The failure was because fh_verify() was doing a permission check as part of verifying the FH presented during the LAYOUTGET. It uses the loga_iomode value to specify the @accmode argument to fh_verify(). fh_verify(MAY_WRITE) on a file whose mode is 0444 fails with -EACCES. To permit LAYOUT* operations in this case, add OWNER_OVERRIDE when checking the access permission of the incoming file handle for LAYOUTGET and LAYOUTCOMMIT. Cc: Christoph Hellwig Cc: stable@vger.kernel.org # v6.6+ Message-Id: 4E9C0D74-A06D-4DC3-A48A-73034DC40395@oracle.com Reviewed-by: Jeff Layton Reviewed-by: Christoph Hellwig Signed-off-by: Chuck Lever --- fs/nfsd/nfs4proc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'fs/nfsd') diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index 46bd20fe5c0f..2e39cf2e502a 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -2269,7 +2269,7 @@ nfsd4_layoutget(struct svc_rqst *rqstp, const struct nfsd4_layout_ops *ops; struct nfs4_layout_stateid *ls; __be32 nfserr; - int accmode = NFSD_MAY_READ_IF_EXEC; + int accmode = NFSD_MAY_READ_IF_EXEC | NFSD_MAY_OWNER_OVERRIDE; switch (lgp->lg_seg.iomode) { case IOMODE_READ: @@ -2359,7 +2359,8 @@ nfsd4_layoutcommit(struct svc_rqst *rqstp, struct nfs4_layout_stateid *ls; __be32 nfserr; - nfserr = fh_verify(rqstp, current_fh, 0, NFSD_MAY_WRITE); + nfserr = fh_verify(rqstp, current_fh, 0, + NFSD_MAY_WRITE | NFSD_MAY_OWNER_OVERRIDE); if (nfserr) goto out; -- cgit v1.2.3