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, 21 insertions, 0 deletions

diff --git a/include/uapi/linux/seg6_hmac.h b/include/uapi/linux/seg6_hmac.h
new file mode 100644
index 000000000000..b652dfd51bc5
--- /dev/null
+++ b/include/uapi/linux/seg6_hmac.h
@@ -0,0 +1,21 @@
+#ifndef _UAPI_LINUX_SEG6_HMAC_H
+#define _UAPI_LINUX_SEG6_HMAC_H
+
+#include <linux/seg6.h>
+
+#define SEG6_HMAC_SECRET_LEN	64
+#define SEG6_HMAC_FIELD_LEN	32
+
+struct sr6_tlv_hmac {
+	struct sr6_tlv tlvhdr;
+	__u16 reserved;
+	__be32 hmackeyid;
+	__u8 hmac[SEG6_HMAC_FIELD_LEN];
+};
+
+enum {
+	SEG6_HMAC_ALGO_SHA1 = 1,
+	SEG6_HMAC_ALGO_SHA256 = 2,
+};
+
+#endif