svcrpc: fix failures to handle -1 uid's and gid's

As of f025adf191924e3a75ce80e130afcd2485b53bb8 "sunrpc: Properly decode
kuids and kgids in RPC_AUTH_UNIX credentials" any rpc containing a -1
(0xffff) uid or gid would fail with a badcred error.

Reported symptoms were xmbc clients failing on upgrade of the NFS
server; examination of the network trace showed them sending -1 as the
gid.

Reported-by: Julian Sikorski <belegdol@gmail.com>
Tested-by: Julian Sikorski <belegdol@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 7 insertions, 5 deletions

diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
index c3f9e1ef7f53..06bdf5a1082c 100644
--- a/net/sunrpc/svcauth_unix.c
+++ b/net/sunrpc/svcauth_unix.c
@@ -810,11 +810,15 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp)
                 goto badcred;
         argv->iov_base = (void*)((__be32*)argv->iov_base + slen);       /* skip machname */
         argv->iov_len -= slen*4;
-
+        /*
+         * Note: we skip uid_valid()/gid_valid() checks here for
+         * backwards compatibility with clients that use -1 id's.
+         * Instead, -1 uid or gid is later mapped to the
+         * (export-specific) anonymous id by nfsd_setuser.
+         * Supplementary gid's will be left alone.
+         */
         cred->cr_uid = make_kuid(&init_user_ns, svc_getnl(argv)); /* uid */
         cred->cr_gid = make_kgid(&init_user_ns, svc_getnl(argv)); /* gid */
-        if (!uid_valid(cred->cr_uid) || !gid_valid(cred->cr_gid))
-                goto badcred;
         slen = svc_getnl(argv);                 /* gids length */
         if (slen > 16 || (len -= (slen + 2)*4) < 0)
                 goto badcred;
@@ -823,8 +827,6 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp)
                 return SVC_CLOSE;
         for (i = 0; i < slen; i++) {
                 kgid_t kgid = make_kgid(&init_user_ns, svc_getnl(argv));
-                if (!gid_valid(kgid))
-                        goto badcred;
                 GROUP_AT(cred->cr_group_info, i) = kgid;
         }
         if (svc_getu32(argv) != htonl(RPC_AUTH_NULL) || svc_getu32(argv) != 0) {