nfsd: return better errors to exportfs

Someone noticed exportfs happily accepted exports that would later be
rejected when mountd tried to give them to the kernel.  Fix this.

This is a regression from 4c1e1b34d5c800ad3ac9a7e2805b0bea70ad2278
"nfsd: Store ex_anon_uid and ex_anon_gid as kuids and kgids".

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: stable@vger.kernel.org
Reported-by: Yin.JianHong <jiyin@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index 5f38ea36e266..af51cf9bf2e3 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -536,16 +536,12 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen)
                 if (err)
                         goto out3;
                 exp.ex_anon_uid= make_kuid(&init_user_ns, an_int);
-                if (!uid_valid(exp.ex_anon_uid))
-                        goto out3;
 
                 /* anon gid */
                 err = get_int(&mesg, &an_int);
                 if (err)
                         goto out3;
                 exp.ex_anon_gid= make_kgid(&init_user_ns, an_int);
-                if (!gid_valid(exp.ex_anon_gid))
-                        goto out3;
 
                 /* fsid */
                 err = get_int(&mesg, &an_int);
@@ -583,6 +579,17 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen)
                                    exp.ex_uuid);
                 if (err)
                         goto out4;
+                /*
+                 * For some reason exportfs has been passing down an
+                 * invalid (-1) uid & gid on the "dummy" export which it
+                 * uses to test export support.  To make sure exportfs
+                 * sees errors from check_export we therefore need to
+                 * delay these checks till after check_export:
+                 */
+                if (!uid_valid(exp.ex_anon_uid))
+                        goto out4;
+                if (!gid_valid(exp.ex_anon_gid))
+                        goto out4;
         }
 
         expp = svc_export_lookup(&exp);