nfsd4: backchannel should use client-provided security flavor

For now this only adds support for AUTH_NULL.  (Previously we assumed
AUTH_UNIX.)  We'll also need AUTH_GSS, which is trickier.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index d7e7c110246e..406d0c4620f6 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -425,7 +425,7 @@ nfsd4_decode_access(struct nfsd4_compoundargs *argp, struct nfsd4_access *access
 static __be32 nfsd4_decode_cb_sec(struct nfsd4_compoundargs *argp, struct nfsd4_cb_sec *cbs)
 {
         DECODE_HEAD;
-        u32 dummy;
+        u32 dummy, uid, gid;
         char *machine_name;
         int i;
         int nr_secflavs;
@@ -433,12 +433,15 @@ static __be32 nfsd4_decode_cb_sec(struct nfsd4_compoundargs *argp, struct nfsd4_
         /* callback_sec_params4 */
         READ_BUF(4);
         READ32(nr_secflavs);
+        cbs->flavor = (u32)(-1);
         for (i = 0; i < nr_secflavs; ++i) {
                 READ_BUF(4);
                 READ32(dummy);
                 switch (dummy) {
                 case RPC_AUTH_NULL:
                         /* Nothing to read */
+                        if (cbs->flavor == (u32)(-1))
+                                cbs->flavor = RPC_AUTH_NULL;
                         break;
                 case RPC_AUTH_UNIX:
                         READ_BUF(8);
@@ -452,13 +455,18 @@ static __be32 nfsd4_decode_cb_sec(struct nfsd4_compoundargs *argp, struct nfsd4_
 
                         /* uid, gid */
                         READ_BUF(8);
-                        READ32(cbs->uid);
-                        READ32(cbs->gid);
+                        READ32(uid);
+                        READ32(gid);
 
                         /* more gids */
                         READ_BUF(4);
                         READ32(dummy);
                         READ_BUF(dummy * 4);
+                        if (cbs->flavor == (u32)(-1)) {
+                                cbs->uid = uid;
+                                cbs->gid = gid;
+                                cbs->flavor = RPC_AUTH_UNIX;
+                        }
                         break;
                 case RPC_AUTH_GSS:
                         dprintk("RPC_AUTH_GSS callback secflavor "