Add documentation clarifying that ARP and routing UAPI structures are
constrained to IPv4-only usage, making them safe for the coming fixed-size
sockaddr conversion (with the 14-byte struct sockaddr::sa_data). These
are fine as-is, but their use was non-obvious to me, so I figured they
could use a little more documentation:
- struct arpreq: ARP protocol is IPv4-only by design
- struct rtentry: Legacy IPv4 routing API, IPv6 uses different structures
Signed-off-by: Kees Cook <k...@kernel.org>
---
Cc: "David S. Miller" <da...@davemloft.net>
Cc: Eric Dumazet <eduma...@google.com>
Cc: Jakub Kicinski <k...@kernel.org>
Cc: Paolo Abeni <pab...@redhat.com>
Cc: Simon Horman <ho...@kernel.org>
Cc: <net...@vger.kernel.org>
---
include/uapi/linux/if_arp.h | 3 ++-
include/uapi/linux/route.h | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/if_arp.h b/include/uapi/linux/if_arp.h
index 4783af9fe520..4164cc6e8aa5 100644
--- a/include/uapi/linux/if_arp.h
+++ b/include/uapi/linux/if_arp.h
@@ -113,7 +113,7 @@
#define ARPOP_NAK 10 /* (ATM)ARP NAK
*/
-/* ARP ioctl request. */
+/* ARP ioctl request; IPv4-only protocol. */
struct arpreq {
struct sockaddr arp_pa; /* protocol address */
struct sockaddr arp_ha; /* hardware address */
@@ -122,6 +122,7 @@ struct arpreq {
char arp_dev[IFNAMSIZ];
};
+/* Legacy ARP ioctl request; IPv4-only protocol. */
struct arpreq_old {
struct sockaddr arp_pa; /* protocol address */
struct sockaddr arp_ha; /* hardware address */
diff --git a/include/uapi/linux/route.h b/include/uapi/linux/route.h
index a0de9a7331a2..a2955e25d7ee 100644
--- a/include/uapi/linux/route.h
+++ b/include/uapi/linux/route.h
@@ -27,7 +27,7 @@
#include <linux/if.h>
#include <linux/compiler.h>
-/* This structure gets passed by the SIOCADDRT and SIOCDELRT calls. */
+/* This IPv4-only structure gets passed by the SIOCADDRT and SIOCDELRT calls.
*/
struct rtentry {
unsigned long rt_pad1;
struct sockaddr rt_dst; /* target address */
--
2.34.1
