nfsd: return better errors to exportfs

commit 427d6c6646d868fbd3094e7e2e1644d480cd9204 upstream.

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>
Reported-by: Yin.JianHong <jiyin@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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);