xfrm: enforce validity of offload input flags

commit 7c76ecd9c99b6e9a771d813ab1aa7fa428b3ade1 upstream.

struct xfrm_user_offload has flags variable that received user input,
but kernel didn't check if valid bits were provided. It caused a situation
where not sanitized input was forwarded directly to the drivers.

For example, XFRM_OFFLOAD_IPV6 define that was exposed, was used by
strongswan, but not implemented in the kernel at all.

As a solution, check and sanitize input flags to forward
XFRM_OFFLOAD_INBOUND to the drivers.

Fixes: d77e38e612a0 ("xfrm: Add an IPsec hardware offloading API")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h
index 2290c98b47cf..90ddb49fce84 100644
--- a/include/uapi/linux/xfrm.h
+++ b/include/uapi/linux/xfrm.h
@@ -506,6 +506,12 @@ struct xfrm_user_offload {
 	int				ifindex;
 	__u8				flags;
 };
+/* This flag was exposed without any kernel code that supporting it.
+ * Unfortunately, strongswan has the code that uses sets this flag,
+ * which makes impossible to reuse this bit.
+ *
+ * So leave it here to make sure that it won't be reused by mistake.
+ */
 #define XFRM_OFFLOAD_IPV6	1
 #define XFRM_OFFLOAD_INBOUND	2