nfsd4: fix gss-proxy 4.1 mounts for some AD principals

The principal name on a gss cred is used to setup the NFSv4.0 callback,
which has to have a client principal name to authenticate to.

That code wants the name to be in the form servicetype@hostname.
rpc.svcgssd passes down such names (and passes down no principal name at
all in the case the principal isn't a service principal).

gss-proxy always passes down the principal name, and passes it down in
the form servicetype/hostname@REALM.  So we've been munging the name
gss-proxy passes down into the format the NFSv4.0 callback code expects,
or throwing away the name if we can't.

Since the introduction of the MACH_CRED enforcement in NFSv4.1, we've
also been using the principal name to verify that certain operations are
done as the same principal as was used on the original EXCHANGE_ID call.

For that application, the original name passed down by gss-proxy is also
useful.

Lack of that name in some cases was causing some kerberized NFSv4.1
mount failures in an Active Directory environment.

This fix only works in the gss-proxy case.  The fix for legacy
rpc.svcgssd would be more involved, and rpc.svcgssd already has other
problems in the AD case.

Reported-and-tested-by: James Ralston <ralston@pobox.com>
Acked-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index ed58ced..113ecbf 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1875,6 +1875,10 @@ static int copy_cred(struct svc_cred *target, struct svc_cred *source)
        ret = strdup_if_nonnull(&target->cr_principal, source->cr_principal);
        if (ret)
                return ret;
+       ret = strdup_if_nonnull(&target->cr_raw_principal,
+                                       source->cr_raw_principal);
+       if (ret)
+               return ret;
        target->cr_flavor = source->cr_flavor;
        target->cr_uid = source->cr_uid;
        target->cr_gid = source->cr_gid;
@@ -1978,6 +1982,9 @@ static bool mach_creds_match(struct nfs4_client *cl, struct svc_rqst *rqstp)
                return false;
        if (!svc_rqst_integrity_protected(rqstp))
                return false;
+       if (cl->cl_cred.cr_raw_principal)
+               return 0 == strcmp(cl->cl_cred.cr_raw_principal,
+                                               cr->cr_raw_principal);
        if (!cr->cr_principal)
                return false;
        return 0 == strcmp(cl->cl_cred.cr_principal, cr->cr_principal);
@@ -2390,7 +2397,8 @@ nfsd4_exchange_id(struct svc_rqst *rqstp,
                 * Which is a bug, really.  Anyway, we can't enforce
                 * MACH_CRED in that case, better to give up now:
                 */
-               if (!new->cl_cred.cr_principal) {
+               if (!new->cl_cred.cr_principal &&
+                                       !new->cl_cred.cr_raw_principal) {
                        status = nfserr_serverfault;
                        goto out_nolock;
                }

diff --git a/include/linux/sunrpc/svcauth.h b/include/linux/sunrpc/svcauth.h
index 8d71d65..c00f53a 100644 (file)
--- a/include/linux/sunrpc/svcauth.h
+++ b/include/linux/sunrpc/svcauth.h
@@ -23,13 +23,19 @@ struct svc_cred {
        kgid_t                  cr_gid;
        struct group_info       *cr_group_info;
        u32                     cr_flavor; /* pseudoflavor */
-       char                    *cr_principal; /* for gss */
+       /* name of form servicetype/hostname@REALM, passed down by
+        * gss-proxy: */
+       char                    *cr_raw_principal;
+       /* name of form servicetype@hostname, passed down by
+        * rpc.svcgssd, or computed from the above: */
+       char                    *cr_principal;
        struct gss_api_mech     *cr_gss_mech;
 };
 
 static inline void init_svc_cred(struct svc_cred *cred)
 {
        cred->cr_group_info = NULL;
+       cred->cr_raw_principal = NULL;
        cred->cr_principal = NULL;
        cred->cr_gss_mech = NULL;
 }
@@ -38,6 +44,7 @@ static inline void free_svc_cred(struct svc_cred *cred)
 {
        if (cred->cr_group_info)
                put_group_info(cred->cr_group_info);
+       kfree(cred->cr_raw_principal);
        kfree(cred->cr_principal);
        gss_mech_put(cred->cr_gss_mech);
        init_svc_cred(cred);

diff --git a/net/sunrpc/auth_gss/gss_rpc_upcall.c b/net/sunrpc/auth_gss/gss_rpc_upcall.c
index 59eeed4..f0c6a8c 100644 (file)
--- a/net/sunrpc/auth_gss/gss_rpc_upcall.c
+++ b/net/sunrpc/auth_gss/gss_rpc_upcall.c
@@ -326,6 +326,9 @@ int gssp_accept_sec_context_upcall(struct net *net,
        if (data->found_creds && client_name.data != NULL) {
                char *c;
 
+               data->creds.cr_raw_principal = kstrndup(client_name.data,
+                                               client_name.len, GFP_KERNEL);
+
                data->creds.cr_principal = kstrndup(client_name.data,
                                                client_name.len, GFP_KERNEL);
                if (data->creds.cr_principal) {