NFS: Determine initial mount security

When sec=<something> is not presented as a mount option,
we should attempt to determine what security flavor the
server is using.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

3 files changed, 50 insertions, 2 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 563463777d9d..f9150f03d640 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -41,6 +41,7 @@
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/gss_api.h>
 #include <linux/nfs.h>
 #include <linux/nfs4.h>
 #include <linux/nfs_fs.h>
@@ -2191,15 +2192,43 @@ static int nfs4_lookup_root(struct nfs_server *server, struct nfs_fh *fhandle,
         return err;
 }
 
+static int nfs4_lookup_root_sec(struct nfs_server *server, struct nfs_fh *fhandle,
+                                struct nfs_fsinfo *info, rpc_authflavor_t flavor)
+{
+        struct rpc_auth *auth;
+        int ret;
+
+        auth = rpcauth_create(flavor, server->client);
+        if (!auth) {
+                ret = -EIO;
+                goto out;
+        }
+        ret = nfs4_lookup_root(server, fhandle, info);
+        if (ret < 0)
+                ret = -EAGAIN;
+out:
+        return ret;
+}
+
 /*
  * get the file handle for the "/" directory on the server
  */
 static int nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,
                               struct nfs_fsinfo *info)
 {
-        int status;
+        int i, len, status = 0;
+        rpc_authflavor_t flav_array[NFS_MAX_SECFLAVORS + 2];
 
-        status = nfs4_lookup_root(server, fhandle, info);
+        flav_array[0] = RPC_AUTH_UNIX;
+        len = gss_mech_list_pseudoflavors(&flav_array[1]);
+        flav_array[1+len] = RPC_AUTH_NULL;
+        len += 2;
+
+        for (i = 0; i < len; i++) {
+                status = nfs4_lookup_root_sec(server, fhandle, info, flav_array[i]);
+                if (status == 0)
+                        break;
+        }
         if (status == 0)
                 status = nfs4_server_capabilities(server, fhandle);
         if (status == 0)
diff --git a/include/linux/sunrpc/gss_api.h b/include/linux/sunrpc/gss_api.h
index 5d8048beb051..332da61cf8b7 100644
--- a/include/linux/sunrpc/gss_api.h
+++ b/include/linux/sunrpc/gss_api.h
@@ -126,6 +126,9 @@ struct gss_api_mech *gss_mech_get_by_name(const char *);
 /* Similar, but get by pseudoflavor. */
 struct gss_api_mech *gss_mech_get_by_pseudoflavor(u32);
 
+/* Fill in an array with a list of supported pseudoflavors */
+int gss_mech_list_pseudoflavors(u32 *);
+
 /* Just increments the mechanism's reference count and returns its input: */
 struct gss_api_mech * gss_mech_get(struct gss_api_mech *);
 
diff --git a/net/sunrpc/auth_gss/gss_mech_switch.c b/net/sunrpc/auth_gss/gss_mech_switch.c
index 6c844b01a1d1..e3c36a274412 100644
--- a/net/sunrpc/auth_gss/gss_mech_switch.c
+++ b/net/sunrpc/auth_gss/gss_mech_switch.c
@@ -215,6 +215,22 @@ gss_mech_get_by_pseudoflavor(u32 pseudoflavor)
 
 EXPORT_SYMBOL_GPL(gss_mech_get_by_pseudoflavor);
 
+int gss_mech_list_pseudoflavors(rpc_authflavor_t *array_ptr)
+{
+        struct gss_api_mech *pos = NULL;
+        int i = 0;
+
+        spin_lock(&registered_mechs_lock);
+        list_for_each_entry(pos, &registered_mechs, gm_list) {
+                array_ptr[i] = pos->gm_pfs->pseudoflavor;
+                i++;
+        }
+        spin_unlock(&registered_mechs_lock);
+        return i;
+}
+
+EXPORT_SYMBOL_GPL(gss_mech_list_pseudoflavors);
+
 u32
 gss_svc_to_pseudoflavor(struct gss_api_mech *gm, u32 service)
 {