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>

1 files changed, 8 insertions, 1 deletions

diff --git a/include/linux/sunrpc/svcauth.h b/include/linux/sunrpc/svcauth.h
index 8d71d6577459..c00f53a4ccdd 100644
--- 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);