NFSv4: Fix problems with close in the presence of a delegation

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@engr.wisc.edu>
Fixes: 88069f77e1ac5 (NFSv41: Fix a potential state leakage when...)
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 5aea30a..c4a2a68 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2004,24 +2004,31 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
 {
        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;
                }
        }