kgssapi: Increase timeout for kernel to gssd(8) upcalls

It turns out that the underlying problem that caused
a Kerberized NFS mount with the "gssname" option to
fail was that the kernel upcall to the gssd(8) daemon
would time out prematurely after 25 seconds.  The
gss_acquire_cred() GSSAPI library call
takes about 27 seconds for the case where a desired_name
argument is specified.  A similarly long delay occurs
when the gss_init_sec_context() call is made and the
user principal's TGT has expired.

Once the upcall timed out, the kernel code assumed that
the gssd(8) daemon had died and closed the socket.
Ironically, closing the socket did cause the gssd(8)
daemon to terminate via a SIGPIPE signal.

This patch increases the timeout to 5 minutes.  Since
a timeout should only occur when the gssd(8) daemon
has died, a long timeout should be ok and seems to fix this
problem.

I still think that commit c33509d49a should remain in the
system, since it allows the mount to complete quickly
and not take nearly 30 seconds.

PR:	268823
MFC after:	2 weeks

1 files changed, 10 insertions, 0 deletions

diff --git a/sys/kgssapi/gss_impl.c b/sys/kgssapi/gss_impl.c
index 07e10d0999c4..9b1277298e32 100644
--- a/sys/kgssapi/gss_impl.c
+++ b/sys/kgssapi/gss_impl.c
@@ -119,7 +119,17 @@ sys_gssd_syscall(struct thread *td, struct gssd_syscall_args *uap)
 		 */
 		if (cl != NULL) {
 			int retry_count = 5;
+			struct timeval timo;
 			CLNT_CONTROL(cl, CLSET_RETRIES, &retry_count);
+
+			/*
+			 * Set the timeout for an upcall to 5 minutes.  The
+			 * default of 25 seconds is not long enough for some
+			 * gss_XXX() calls done by the gssd(8) daemon.
+			 */
+			timo.tv_sec = 5 * 60;
+			timo.tv_usec = 0;
+			CLNT_CONTROL(cl, CLSET_TIMEOUT, &timo);
 		}
 	} else
 		cl = NULL;