NFSv4: Fix security auto-negotiation

NFSv4 security auto-negotiation has been broken since
commit 4580a92d44e2b21c2254fa5fef0f1bfb43c82318 (NFS:
Use server-recommended security flavor by default (NFSv3))
because nfs4_try_mount() will automatically select AUTH_SYS
if it sees no auth flavours.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Chuck Lever <chuck.lever@oracle.com>

6 files changed, 30 insertions, 18 deletions

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 23ec6e8e8a4d..d388302c005f 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -358,7 +358,7 @@ extern struct dentry *nfs_get_root(struct super_block *, struct nfs_fh *,
 extern struct dentry *nfs4_get_root(struct super_block *, struct nfs_fh *,
                                     const char *);
 
-extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh);
+extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool);
 #endif
 
 struct nfs_pgio_completion_ops;
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index d2db3ce07d3a..f520a1113b38 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -221,7 +221,7 @@ struct vfsmount *nfs4_submount(struct nfs_server *, struct dentry *,
 /* nfs4proc.c */
 extern int nfs4_proc_setclientid(struct nfs_client *, u32, unsigned short, struct rpc_cred *, struct nfs4_setclientid_res *);
 extern int nfs4_proc_setclientid_confirm(struct nfs_client *, struct nfs4_setclientid_res *arg, struct rpc_cred *);
-extern int nfs4_proc_get_rootfh(struct nfs_server *, struct nfs_fh *, struct nfs_fsinfo *);
+extern int nfs4_proc_get_rootfh(struct nfs_server *, struct nfs_fh *, struct nfs_fsinfo *, bool);
 extern int nfs4_proc_bind_conn_to_session(struct nfs_client *, struct rpc_cred *cred);
 extern int nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred);
 extern int nfs4_destroy_clientid(struct nfs_client *clp);
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index f798925d8291..cc80085c4de4 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -885,7 +885,7 @@ static void nfs4_session_set_rwsize(struct nfs_server *server)
 }
 
 static int nfs4_server_common_setup(struct nfs_server *server,
-                struct nfs_fh *mntfh)
+                struct nfs_fh *mntfh, bool auth_probe)
 {
         struct nfs_fattr *fattr;
         int error;
@@ -917,7 +917,7 @@ static int nfs4_server_common_setup(struct nfs_server *server,
 
 
         /* Probe the root fh to retrieve its FSID and filehandle */
-        error = nfs4_get_rootfh(server, mntfh);
+        error = nfs4_get_rootfh(server, mntfh, auth_probe);
         if (error < 0)
                 goto out;
 
@@ -949,6 +949,7 @@ out:
 static int nfs4_init_server(struct nfs_server *server,
                 const struct nfs_parsed_mount_data *data)
 {
+        rpc_authflavor_t pseudoflavor = RPC_AUTH_UNIX;
         struct rpc_timeout timeparms;
         int error;
 
@@ -961,13 +962,16 @@ static int nfs4_init_server(struct nfs_server *server,
         server->flags = data->flags;
         server->options = data->options;
 
+        if (data->auth_flavor_len >= 1)
+                pseudoflavor = data->auth_flavors[0];
+
         /* Get a client record */
         error = nfs4_set_client(server,
                         data->nfs_server.hostname,
                         (const struct sockaddr *)&data->nfs_server.address,
                         data->nfs_server.addrlen,
                         data->client_address,
-                        data->auth_flavors[0],
+                        pseudoflavor,
                         data->nfs_server.protocol,
                         &timeparms,
                         data->minorversion,
@@ -987,7 +991,7 @@ static int nfs4_init_server(struct nfs_server *server,
 
         server->port = data->nfs_server.port;
 
-        error = nfs_init_server_rpcclient(server, &timeparms, data->auth_flavors[0]);
+        error = nfs_init_server_rpcclient(server, &timeparms, pseudoflavor);
 
 error:
         /* Done */
@@ -1005,6 +1009,7 @@ struct nfs_server *nfs4_create_server(struct nfs_mount_info *mount_info,
                                       struct nfs_subversion *nfs_mod)
 {
         struct nfs_server *server;
+        bool auth_probe;
         int error;
 
         dprintk("--> nfs4_create_server()\n");
@@ -1013,12 +1018,14 @@ struct nfs_server *nfs4_create_server(struct nfs_mount_info *mount_info,
         if (!server)
                 return ERR_PTR(-ENOMEM);
 
+        auth_probe = mount_info->parsed->auth_flavor_len < 1;
+
         /* set up the general RPC client */
         error = nfs4_init_server(server, mount_info->parsed);
         if (error < 0)
                 goto error;
 
-        error = nfs4_server_common_setup(server, mount_info->mntfh);
+        error = nfs4_server_common_setup(server, mount_info->mntfh, auth_probe);
         if (error < 0)
                 goto error;
 
@@ -1071,7 +1078,7 @@ struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *data,
         if (error < 0)
                 goto error;
 
-        error = nfs4_server_common_setup(server, mntfh);
+        error = nfs4_server_common_setup(server, mntfh, false);
         if (error < 0)
                 goto error;
 
diff --git a/fs/nfs/nfs4getroot.c b/fs/nfs/nfs4getroot.c
index 549462e5b9b0..c0b3a16b4a00 100644
--- a/fs/nfs/nfs4getroot.c
+++ b/fs/nfs/nfs4getroot.c
@@ -9,7 +9,7 @@
 
 #define NFSDBG_FACILITY         NFSDBG_CLIENT
 
-int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh)
+int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool auth_probe)
 {
         struct nfs_fsinfo fsinfo;
         int ret = -ENOMEM;
@@ -21,7 +21,7 @@ int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh)
                 goto out;
 
         /* Start by getting the root filehandle from the server */
-        ret = nfs4_proc_get_rootfh(server, mntfh, &fsinfo);
+        ret = nfs4_proc_get_rootfh(server, mntfh, &fsinfo, auth_probe);
         if (ret < 0) {
                 dprintk("nfs4_get_rootfh: getroot error = %d\n", -ret);
                 goto out;
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index cb56102ad40e..68551ea0b673 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2884,18 +2884,27 @@ static int nfs4_do_find_root_sec(struct nfs_server *server,
  * @server: initialized nfs_server handle
  * @fhandle: we fill in the pseudo-fs root file handle
  * @info: we fill in an FSINFO struct
+ * @auth_probe: probe the auth flavours
  *
  * Returns zero on success, or a negative errno.
  */
 int nfs4_proc_get_rootfh(struct nfs_server *server, struct nfs_fh *fhandle,
-                         struct nfs_fsinfo *info)
+                         struct nfs_fsinfo *info,
+                         bool auth_probe)
 {
         int status;
 
-        status = nfs4_lookup_root(server, fhandle, info);
-        if ((status == -NFS4ERR_WRONGSEC) &&
-            !(server->flags & NFS_MOUNT_SECFLAVOUR))
+        switch (auth_probe) {
+        case false:
+                status = nfs4_lookup_root(server, fhandle, info);
+                if (status != -NFS4ERR_WRONGSEC)
+                        break;
+                /* Did user force a 'sec=' mount option? */
+                if (server->flags & NFS_MOUNT_SECFLAVOUR)
+                        break;
+        default:
                 status = nfs4_do_find_root_sec(server, fhandle, info);
+        }
 
         if (status == 0)
                 status = nfs4_server_capabilities(server, fhandle);
diff --git a/fs/nfs/nfs4super.c b/fs/nfs/nfs4super.c
index 4ad837cf4786..e26acdd1a645 100644
--- a/fs/nfs/nfs4super.c
+++ b/fs/nfs/nfs4super.c
@@ -253,10 +253,6 @@ struct dentry *nfs4_try_mount(int flags, const char *dev_name,
 
         dfprintk(MOUNT, "--> nfs4_try_mount()\n");
 
-        if (data->auth_flavor_len < 1) {
-                data->auth_flavors[0] = RPC_AUTH_UNIX;
-                data->auth_flavor_len = 1;
-        }
         export_path = data->nfs_server.export_path;
         data->nfs_server.export_path = "/";
         root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, mount_info,