[PATCH 3.2 088/131] NFSv4: Fix problems with close in the presence of a delegation

[Ben Hutchings]

3.2.63-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>

commit aee7af356e151494d5014f57b33460b162f181b5 upstream.

In the presence of delegations, we can no longer assume that the
state->n_rdwr, state->n_rdonly, state->n_wronly reflect the open
stateid share mode, and so we need to calculate the initial value
for calldata->arg.fmode using the state->flags.

Reported-by: James Drews <drews@xxxxxxxxxxxxx>
Fixes: 88069f77e1ac5 (NFSv41: Fix a potential state leakage when...)
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 fs/nfs/nfs4proc.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2004,24 +2004,31 @@ static void nfs4_close_prepare(struct rp
 {
 	struct nfs4_closedata *calldata = data;
 	struct nfs4_state *state = calldata->state;
+	bool is_rdonly, is_wronly, is_rdwr;
 	int call_close = 0;
 
 	if (nfs_wait_on_sequence(calldata->arg.seqid, task) != 0)
 		return;
 
 	task->tk_msg.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_OPEN_DOWNGRADE];
-	calldata->arg.fmode = FMODE_READ|FMODE_WRITE;
 	spin_lock(&state->owner->so_lock);
+	is_rdwr = test_bit(NFS_O_RDWR_STATE, &state->flags);
+	is_rdonly = test_bit(NFS_O_RDONLY_STATE, &state->flags);
+	is_wronly = test_bit(NFS_O_WRONLY_STATE, &state->flags);
+	/* Calculate the current open share mode */
+	calldata->arg.fmode = 0;
+	if (is_rdonly || is_rdwr)
+		calldata->arg.fmode |= FMODE_READ;
+	if (is_wronly || is_rdwr)
+		calldata->arg.fmode |= FMODE_WRITE;
 	/* Calculate the change in open mode */
 	if (state->n_rdwr == 0) {
 		if (state->n_rdonly == 0) {
-			call_close |= test_bit(NFS_O_RDONLY_STATE, &state->flags);
-			call_close |= test_bit(NFS_O_RDWR_STATE, &state->flags);
+			call_close |= is_rdonly || is_rdwr;
 			calldata->arg.fmode &= ~FMODE_READ;
 		}
 		if (state->n_wronly == 0) {
-			call_close |= test_bit(NFS_O_WRONLY_STATE, &state->flags);
-			call_close |= test_bit(NFS_O_RDWR_STATE, &state->flags);
+			call_close |= is_wronly || is_rdwr;
 			calldata->arg.fmode &= ~FMODE_WRITE;
 		}
 	}

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