NFSv4.1: try SECINFO_NO_NAME flavs until one works

Call nfs4_lookup_root_sec for each flavor returned by SECINFO_NO_NAME until
one works.

One example of a situation this fixes:

 - server configured for krb5
 - server principal somehow gets deleted from KDC
 - server still thinking krb is good, sends krb5 as first entry in
    SECINFO_NO_NAME response
 - client tries krb5, but this fails without even sending an RPC because
    gssd's requests to the KDC can't find the server's principal

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

1 files changed, 27 insertions, 3 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 488ef9b5c51a..f5fe16bd426c 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -7578,6 +7578,8 @@ nfs41_find_root_sec(struct nfs_server *server, struct nfs_fh *fhandle,
         struct page *page;
         rpc_authflavor_t flavor;
         struct nfs4_secinfo_flavors *flavors;
+        struct nfs4_secinfo4 *secinfo;
+        int i;
 
         page = alloc_page(GFP_KERNEL);
         if (!page) {
@@ -7599,9 +7601,31 @@ nfs41_find_root_sec(struct nfs_server *server, struct nfs_fh *fhandle,
         if (err)
                 goto out_freepage;
 
-        flavor = nfs_find_best_sec(flavors);
-        if (err == 0)
-                err = nfs4_lookup_root_sec(server, fhandle, info, flavor);
+        for (i = 0; i < flavors->num_flavors; i++) {
+                secinfo = &flavors->flavors[i];
+
+                switch (secinfo->flavor) {
+                case RPC_AUTH_NULL:
+                case RPC_AUTH_UNIX:
+                case RPC_AUTH_GSS:
+                        flavor = rpcauth_get_pseudoflavor(secinfo->flavor,
+                                        &secinfo->flavor_info);
+                        break;
+                default:
+                        flavor = RPC_AUTH_MAXFLAVOR;
+                        break;
+                }
+
+                if (flavor != RPC_AUTH_MAXFLAVOR) {
+                        err = nfs4_lookup_root_sec(server, fhandle,
+                                                   info, flavor);
+                        if (!err)
+                                break;
+                }
+        }
+
+        if (flavor == RPC_AUTH_MAXFLAVOR)
+                err = -EPERM;
 
 out_freepage:
         put_page(page);