[PATCH] cifs.upcall: bump SPNEGO msg version number and don't reject old versions

[Jeff Layton]

When we added the ability for the kernel to send sec=mskrb5 to the
upcall, we subtly broke old cifs.upcall versions that don't understand
it. Bump the spnego message version to 2 to make this clear. Also,
change cifs.upcall to not reject requests with a version that's lower
than the current one, and to send the reply with the same version that
the request sent. The idea is to try and keep cifs.upcall backward
compatible with old kernels.

Signed-off-by: Jeff Layton <jlayton at redhat.com>
---
 source/client/cifs.upcall.c |    4 ++--
 source/client/cifs_spnego.h |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/source/client/cifs.upcall.c b/source/client/cifs.upcall.c
index cf5f1c3..7cb5166 100644
--- a/source/client/cifs.upcall.c
+++ b/source/client/cifs.upcall.c
@@ -284,7 +284,7 @@ int main(const int argc, char *const argv[])
 	}
 	SAFE_FREE(buf);
 
-	if (kernel_upcall_version != CIFS_SPNEGO_UPCALL_VERSION) {
+	if (kernel_upcall_version > CIFS_SPNEGO_UPCALL_VERSION) {
 		syslog(LOG_WARNING,
 		       "incompatible kernel upcall version: 0x%x",
 		       kernel_upcall_version);
@@ -353,7 +353,7 @@ int main(const int argc, char *const argv[])
 		rc = 1;
 		goto out;
 	}
-	keydata->version = CIFS_SPNEGO_UPCALL_VERSION;
+	keydata->version = kernel_upcall_version;
 	keydata->flags = 0;
 	keydata->sesskey_len = sess_key.length;
 	keydata->secblob_len = secblob.length;
diff --git a/source/client/cifs_spnego.h b/source/client/cifs_spnego.h
index 13909dd..f8753a7 100644
--- a/source/client/cifs_spnego.h
+++ b/source/client/cifs_spnego.h
@@ -23,7 +23,7 @@
 #ifndef _CIFS_SPNEGO_H
 #define _CIFS_SPNEGO_H
 
-#define CIFS_SPNEGO_UPCALL_VERSION 1
+#define CIFS_SPNEGO_UPCALL_VERSION 2
 
 /*
  * The version field should always be set to CIFS_SPNEGO_UPCALL_VERSION.
-- 
1.5.5.1