NFSv4: Add ACCESS operation to OPEN compound

The OPEN operation has no way to differentiate an open for read and an
open for execution - both look like read to the server. This allowed
users to read files that didn't have READ access but did have EXEC access,
which is obviously wrong.

This patch adds an ACCESS call to the OPEN compound to handle the
difference between OPENs for reading and execution.  Since we're going
through the trouble of calling ACCESS, we check all possible access bits
and cache the results hopefully avoiding an ACCESS call in the future.

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 44 insertions, 8 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 471a75f11ea2..5b3207f557d9 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -104,6 +104,8 @@ static int nfs4_map_errors(int err)
 		return -EACCES;
 	case -NFS4ERR_MINOR_VERS_MISMATCH:
 		return -EPROTONOSUPPORT;
+	case -NFS4ERR_ACCESS:
+		return -EACCES;
 	default:
 		dprintk("%s could not handle NFSv4 error %d\n",
 				__func__, -err);
@@ -860,6 +862,9 @@ static struct nfs4_opendata *nfs4_opendata_alloc(struct dentry *dentry,
 	p->o_arg.fh = NFS_FH(dir);
 	p->o_arg.open_flags = flags;
 	p->o_arg.fmode = fmode & (FMODE_READ|FMODE_WRITE);
+	/* ask server to check for all possible rights as results are cached */
+	p->o_arg.access = NFS4_ACCESS_READ | NFS4_ACCESS_MODIFY |
+			  NFS4_ACCESS_EXTEND | NFS4_ACCESS_EXECUTE;
 	p->o_arg.clientid = server->nfs_client->cl_clientid;
 	p->o_arg.id.create_time = ktime_to_ns(sp->so_seqid.create_time);
 	p->o_arg.id.uniquifier = sp->so_seqid.owner_id;
@@ -1643,6 +1648,39 @@ static int _nfs4_recover_proc_open(struct nfs4_opendata *data)
 	return status;
 }
 
+static int nfs4_opendata_access(struct rpc_cred *cred,
+				struct nfs4_opendata *opendata,
+				struct nfs4_state *state, fmode_t fmode)
+{
+	struct nfs_access_entry cache;
+	u32 mask;
+
+	/* access call failed or for some reason the server doesn't
+	 * support any access modes -- defer access call until later */
+	if (opendata->o_res.access_supported == 0)
+		return 0;
+
+	mask = 0;
+	if (fmode & FMODE_READ)
+		mask |= MAY_READ;
+	if (fmode & FMODE_WRITE)
+		mask |= MAY_WRITE;
+	if (fmode & FMODE_EXEC)
+		mask |= MAY_EXEC;
+
+	cache.cred = cred;
+	cache.jiffies = jiffies;
+	nfs_access_set_mask(&cache, opendata->o_res.access_result);
+	nfs_access_add_cache(state->inode, &cache);
+
+	if ((mask & ~cache.mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
+		return 0;
+
+	/* even though OPEN succeeded, access is denied. Close the file */
+	nfs4_close_state(state, fmode);
+	return -NFS4ERR_ACCESS;
+}
+
 /*
  * Note: On error, nfs4_proc_open will free the struct nfs4_opendata
  */
@@ -1900,6 +1938,10 @@ static int _nfs4_do_open(struct inode *dir,
 	if (server->caps & NFS_CAP_POSIX_LOCK)
 		set_bit(NFS_STATE_POSIX_LOCKS, &state->flags);
 
+	status = nfs4_opendata_access(cred, opendata, state, fmode);
+	if (status != 0)
+		goto err_opendata_put;
+
 	if (opendata->o_arg.open_flags & O_EXCL) {
 		nfs4_exclusive_attrset(opendata, sattr);
 
@@ -1945,7 +1987,7 @@ static struct nfs4_state *nfs4_do_open(struct inode *dir,
 	struct nfs4_state *res;
 	int status;
 
-	fmode &= FMODE_READ|FMODE_WRITE;
+	fmode &= FMODE_READ|FMODE_WRITE|FMODE_EXEC;
 	do {
 		status = _nfs4_do_open(dir, dentry, fmode, flags, sattr, cred,
 				       &res, ctx_th);
@@ -2771,13 +2813,7 @@ static int _nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry
 
 	status = nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
 	if (!status) {
-		entry->mask = 0;
-		if (res.access & NFS4_ACCESS_READ)
-			entry->mask |= MAY_READ;
-		if (res.access & (NFS4_ACCESS_MODIFY | NFS4_ACCESS_EXTEND | NFS4_ACCESS_DELETE))
-			entry->mask |= MAY_WRITE;
-		if (res.access & (NFS4_ACCESS_LOOKUP|NFS4_ACCESS_EXECUTE))
-			entry->mask |= MAY_EXEC;
+		nfs_access_set_mask(entry, res.access);
 		nfs_refresh_inode(inode, res.fattr);
 	}
 	nfs_free_fattr(res.fattr);