packet: support extensible, 64 bit clean mmaped ring structure

The tpacket_hdr is not 64 bit clean due to use of an unsigned long
and can't be extended because the following struct sockaddr_ll needs
to be at a fixed offset.

Add support for a version 2 tpacket protocol that removes these
limitations.

Userspace can query the header size through a new getsockopt option
and change the protocol version through a setsockopt option. The
changes needed to switch to the new protocol version are:

1. replace struct tpacket_hdr by struct tpacket2_hdr
2. query header len and save
3. set protocol version to 2
 - set up ring as usual
4. for getting the sockaddr_ll, use (void *)hdr + TPACKET_ALIGN(hdrlen)
   instead of (void *)hdr + TPACKET_ALIGN(sizeof(struct tpacket_hdr))

Steps 2 and 4 can be omitted if the struct sockaddr_ll isn't needed.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index ad09609..d4d3c82 100644
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -43,6 +43,8 @@ struct sockaddr_ll
 #define PACKET_COPY_THRESH		7
 #define PACKET_AUXDATA			8
 #define PACKET_ORIGDEV			9
+#define PACKET_VERSION			10
+#define PACKET_HDRLEN			11
 
 struct tpacket_stats
 {
@@ -79,6 +81,25 @@ struct tpacket_hdr
 #define TPACKET_ALIGN(x)	(((x)+TPACKET_ALIGNMENT-1)&~(TPACKET_ALIGNMENT-1))
 #define TPACKET_HDRLEN		(TPACKET_ALIGN(sizeof(struct tpacket_hdr)) + sizeof(struct sockaddr_ll))
 
+struct tpacket2_hdr
+{
+	__u32		tp_status;
+	__u32		tp_len;
+	__u32		tp_snaplen;
+	__u16		tp_mac;
+	__u16		tp_net;
+	__u32		tp_sec;
+	__u32		tp_nsec;
+};
+
+#define TPACKET2_HDRLEN		(TPACKET_ALIGN(sizeof(struct tpacket2_hdr)) + sizeof(struct sockaddr_ll))
+
+enum tpacket_versions
+{
+	TPACKET_V1,
+	TPACKET_V2,
+};
+
 /*
    Frame structure: