ipv6: sr: add core files for SR HMAC support

This patch adds the necessary functions to compute and check the HMAC signature
of an SR-enabled packet. Two HMAC algorithms are supported: hmac(sha1) and
hmac(sha256).

In order to avoid dynamic memory allocation for each HMAC computation,
a per-cpu ring buffer is allocated for this purpose.

A new per-interface sysctl called seg6_require_hmac is added, allowing a
user-defined policy for processing HMAC-signed SR-enabled packets.
A value of -1 means that the HMAC field will always be ignored.
A value of 0 means that if an HMAC field is present, its validity will
be enforced (the packet is dropped is the signature is incorrect).
Finally, a value of 1 means that any SR-enabled packet that does not
contain an HMAC signature or whose signature is incorrect will be dropped.

Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 68d3f71f0abf..93756585521f 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -65,6 +65,9 @@ struct ipv6_devconf {
 	__s32		use_oif_addrs_only;
 	__s32		keep_addr_on_down;
 	__s32		seg6_enabled;
+#ifdef CONFIG_IPV6_SEG6_HMAC
+	__s32		seg6_require_hmac;
+#endif
 
 	struct ctl_table_header *sysctl_header;
 };