ospf6d: Core functionality of auth trailer implementation..

Problem Statement:
==================
Implement RFC 7166 support for OSPF6 in FRR code.

RCA:
====
This feature is newly supported in FRR.

Fix:
====
Changes are done to implement ospf6 ingress and egress
packet processing.
This commit has the core functionality.

It supports below debugability commands:
---------------------------------------
debug ospf6 authentication [<tx|rx>]

It supports below clear command:
--------------------------------
clear ipv6 ospf6 auth-counters interface [IFNAME]

It supports below show commands:
--------------------------------
frr# show ipv6 ospf6 interface ens192
ens192 is up, type BROADCAST
  Interface ID: 5
  Number of I/F scoped LSAs is 2
    0 Pending LSAs for LSUpdate in Time 00:00:00 [thread off]
    0 Pending LSAs for LSAck in Time 00:00:00 [thread off]
  Authentication trailer is enabled with manual key         ==> new info added
    Packet drop Tx 0, Packet drop Rx 0			    ==> drop counters

frr# show ipv6 ospf6 neighbor 2.2.2.2 detail
 Neighbor 2.2.2.2%ens192
    Area 1 via interface ens192 (ifindex 3)
    0 Pending LSAs for LSUpdate in Time 00:00:00 [thread off]
    0 Pending LSAs for LSAck in Time 00:00:00 [thread off]
    Authentication header present                           ==> new info added
                         hello        DBDesc       LSReq        LSUpd        LSAck
      Higher sequence no 0x0          0x0          0x0          0x0          0x0
      Lower sequence no  0x242E       0x1DC4       0x1DC3       0x23CC       0x1DDA

frr# show ipv6 ospf6
 OSPFv3 Routing Process (0) with Router-ID 2.2.2.2
 Number of areas in this router is 1
 Authentication Sequence number info                       ==> new info added
  Higher sequence no 3, Lower sequence no 1656

Risk:
=====
Low risk

Tests Executed:
===============
Have executed the combination of commands.

Signed-off-by: Abhinay Ramesh <rabhinay@vmware.com>

4 files changed, 912 insertions, 0 deletions

diff --git a/ospf6d/ospf6_auth_trailer.c b/ospf6d/ospf6_auth_trailer.c
new file mode 100644
index 000000000..88d2fc240
--- /dev/null
+++ b/ospf6d/ospf6_auth_trailer.c
@@ -0,0 +1,828 @@
+/*
+ * Copyright (C) 2021 Abhinay Ramesh
+ *
+ * This file is part of GNU Zebra.
+ *
+ * GNU Zebra is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * GNU Zebra is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "zebra.h"
+#include "memory.h"
+#include "ospf6d.h"
+#include "vty.h"
+#include "command.h"
+#include "md5.h"
+#include "sha256.h"
+#include "lib/zlog.h"
+#include "ospf6_message.h"
+#include "ospf6_interface.h"
+#include "ospf6_neighbor.h"
+#include "ospf6_proto.h"
+#include "ospf6_auth_trailer.h"
+#include "ospf6_route.h"
+#include "ospf6_zebra.h"
+#include "lib/keychain.h"
+
+unsigned char conf_debug_ospf6_auth[2];
+DEFINE_MTYPE_STATIC(OSPF6D, OSPF6_AUTH_PKT, "OSPF6 auth packet");
+DEFINE_MTYPE_STATIC(OSPF6D, OSPF6_AUTH_HASH, "OSPF6 auth hash");
+DEFINE_MTYPE_STATIC(OSPF6D, OSPF6_AUTH_HASH_XOR, "OSPF6 auth hash xor");
+
+/*Apad is the hexadecimal value 0x878FE1F3. */
+const uint8_t ospf6_hash_apad_max[KEYCHAIN_MAX_HASH_SIZE] = {
+	0x87, 0x8f, 0xe1, 0xf3, 0x87, 0x8f, 0xe1, 0xf3, 0x87, 0x8f, 0xe1,
+	0xf3, 0x87, 0x8f, 0xe1, 0xf3, 0x87, 0x8f, 0xe1, 0xf3, 0x87, 0x8f,
+	0xe1, 0xf3, 0x87, 0x8f, 0xe1, 0xf3, 0x87, 0x8f, 0xe1, 0xf3, 0x87,
+	0x8f, 0xe1, 0xf3, 0x87, 0x8f, 0xe1, 0xf3, 0x87, 0x8f, 0xe1, 0xf3,
+	0x87, 0x8f, 0xe1, 0xf3, 0x87, 0x8f, 0xe1, 0xf3, 0x87, 0x8f, 0xe1,
+	0xf3, 0x87, 0x8f, 0xe1, 0xf3, 0x87, 0x8f, 0xe1, 0xf3,
+};
+
+const uint8_t ospf6_hash_ipad_max[KEYCHAIN_ALGO_MAX_INTERNAL_BLK_SIZE] = {
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+	0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
+};
+
+const uint8_t ospf6_hash_opad_max[KEYCHAIN_ALGO_MAX_INTERNAL_BLK_SIZE] = {
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+	0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
+};
+
+void ospf6_auth_hdr_dump_send(struct ospf6_header *ospfh, uint16_t length)
+{
+	struct ospf6_auth_hdr *ospf6_at_hdr;
+	int at_len, oh_len, at_hdr_len, hash_len;
+	unsigned char temp[KEYCHAIN_MAX_HASH_SIZE+1];
+
+	oh_len = htons(ospfh->length);
+	at_len = length - oh_len;
+	if (at_len > 0) {
+		ospf6_at_hdr = (struct ospf6_auth_hdr *)
+					((uint8_t *)ospfh + oh_len);
+		at_hdr_len = htons(ospf6_at_hdr->length);
+		hash_len = at_hdr_len - OSPF6_AUTH_HDR_MIN_SIZE;
+		memcpy(temp, ospf6_at_hdr->data, hash_len);
+		temp[hash_len] = '\0';
+		zlog_debug("OSPF6 Authentication Trailer");
+		zlog_debug("  Type %d", htons(ospf6_at_hdr->type));
+		zlog_debug("  Length %d", at_hdr_len);
+		zlog_debug("  Reserved %d", ospf6_at_hdr->reserved);
+		zlog_debug("  SA ID %d", htons(ospf6_at_hdr->id));
+		zlog_debug("  seqnum high 0x%08x",
+			   htonl(ospf6_at_hdr->seqnum_h));
+		zlog_debug("  seqnum high 0x%08x",
+			   htonl(ospf6_at_hdr->seqnum_l));
+		zlog_debug("  Data %s", temp);
+	}
+}
+
+void ospf6_auth_hdr_dump_recv(struct ospf6_header *ospfh, uint16_t length)
+{
+	struct ospf6_auth_hdr *ospf6_at_hdr;
+	int at_len, oh_len, at_hdr_len, hash_len;
+	unsigned char temp[KEYCHAIN_MAX_HASH_SIZE+1];
+
+	oh_len = ntohs(ospfh->length);
+	at_len = length - oh_len;
+	if (at_len > 0) {
+		ospf6_at_hdr = (struct ospf6_auth_hdr *)
+					((uint8_t *)ospfh + oh_len);
+		at_hdr_len = ntohs(ospf6_at_hdr->length);
+		hash_len = at_hdr_len - OSPF6_AUTH_HDR_MIN_SIZE;
+		memcpy(temp, ospf6_at_hdr->data, hash_len);
+		temp[hash_len] = '\0';
+		zlog_debug("OSPF6 Authentication Trailer");
+		zlog_debug("  Type %d", ntohs(ospf6_at_hdr->type));
+		zlog_debug("  Length %d", at_hdr_len);
+		zlog_debug("  Reserved %d", ospf6_at_hdr->reserved);
+		zlog_debug("  SA ID %d", ntohs(ospf6_at_hdr->id));
+		zlog_debug("  seqnum high 0x%08x",
+			   ntohl(ospf6_at_hdr->seqnum_h));
+		zlog_debug("  seqnum high 0x%08x",
+			   ntohl(ospf6_at_hdr->seqnum_l));
+		zlog_debug("  Data %s", temp);
+	}
+}
+
+unsigned char *ospf6_hash_message_xor(unsigned char *mes1,
+				      unsigned char *mes2,
+				      uint32_t len)
+{
+	unsigned char *result;
+	uint32_t i;
+
+	result = XCALLOC(MTYPE_OSPF6_AUTH_HASH_XOR, len);
+	if (!result)
+		return NULL;
+
+	for (i = 0; i < len; i++)
+		result[i] = mes1[i] ^ mes2[i];
+
+	return result;
+}
+
+static void md5_digest(unsigned char *mes, uint32_t len,
+		       unsigned char *digest)
+{
+#ifdef CRYPTO_OPENSSL
+	unsigned int size = KEYCHAIN_MD5_HASH_SIZE;
+	EVP_MD_CTX *ctx;
+#elif CRYPTO_INTERNAL
+	MD5_CTX ctx;
+#endif
+
+#ifdef CRYPTO_OPENSSL
+	ctx = EVP_MD_CTX_new();
+	EVP_DigestInit(ctx, EVP_md5());
+	EVP_DigestUpdate(ctx, mes, len);
+	EVP_DigestFinal(ctx, digest, &size);
+	EVP_MD_CTX_free(ctx);
+#elif CRYPTO_INTERNAL
+	memset(&ctx, 0, sizeof(ctx));
+	MD5Init(&ctx);
+	MD5Update(&ctx, mes, len);
+	MD5Final(digest, &ctx);
+#endif
+}
+
+static void sha256_digest(unsigned char *mes, uint32_t len,
+			  unsigned char *digest)
+{
+#ifdef CRYPTO_OPENSSL
+	unsigned int size = KEYCHAIN_HMAC_SHA256_HASH_SIZE;
+	EVP_MD_CTX *ctx;
+#elif CRYPTO_INTERNAL
+	SHA256_CTX ctx;
+#endif
+
+#ifdef CRYPTO_OPENSSL
+	ctx = EVP_MD_CTX_new();
+	EVP_DigestInit(ctx, EVP_sha256());
+	EVP_DigestUpdate(ctx, mes, len);
+	EVP_DigestFinal(ctx, digest, &size);
+	EVP_MD_CTX_free(ctx);
+#elif CRYPTO_INTERNAL
+	memset(&ctx, 0, sizeof(ctx));
+	SHA256_Init(&ctx);
+	SHA256_Update(&ctx, mes, len);
+	SHA256_Final(digest, &ctx);
+#endif
+}
+
+#ifdef CRYPTO_OPENSSL
+static void sha1_digest(unsigned char *mes, uint32_t len,
+			unsigned char *digest)
+{
+	EVP_MD_CTX *ctx;
+	unsigned int size = KEYCHAIN_HMAC_SHA1_HASH_SIZE;
+
+	ctx = EVP_MD_CTX_new();
+	EVP_DigestInit(ctx, EVP_sha1());
+	EVP_DigestUpdate(ctx, mes, len);
+	EVP_DigestFinal(ctx, digest, &size);
+	EVP_MD_CTX_free(ctx);
+}
+
+static void sha384_digest(unsigned char *mes, uint32_t len,
+			  unsigned char *digest)
+{
+	EVP_MD_CTX *ctx;
+	unsigned int size = KEYCHAIN_HMAC_SHA384_HASH_SIZE;
+
+	ctx = EVP_MD_CTX_new();
+	EVP_DigestInit(ctx, EVP_sha384());
+	EVP_DigestUpdate(ctx, mes, len);
+	EVP_DigestFinal(ctx, digest, &size);
+	EVP_MD_CTX_free(ctx);
+}
+
+static void sha512_digest(unsigned char *mes, uint32_t len,
+			  unsigned char *digest)
+{
+	EVP_MD_CTX *ctx;
+	unsigned int size = KEYCHAIN_HMAC_SHA512_HASH_SIZE;
+
+	ctx = EVP_MD_CTX_new();
+	EVP_DigestInit(ctx, EVP_sha512());
+	EVP_DigestUpdate(ctx, mes, len);
+	EVP_DigestFinal(ctx, digest, &size);
+	EVP_MD_CTX_free(ctx);
+}
+#endif /* CRYPTO_OPENSSL */
+
+static void ospf6_hash_hmac_sha_digest(enum keychain_hash_algo key,
+				       unsigned char *mes, uint32_t len,
+				       unsigned char *digest)
+{
+	if ((key <= KEYCHAIN_ALGO_NULL) || (key >= KEYCHAIN_ALGO_MAX))
+		return;
+
+	switch (key) {
+	case KEYCHAIN_ALGO_MD5:
+		md5_digest(mes, len, digest);
+		break;
+	case KEYCHAIN_ALGO_HMAC_SHA1:
+#ifdef CRYPTO_OPENSSL
+		sha1_digest(mes, len, digest);
+#endif
+		break;
+	case KEYCHAIN_ALGO_HMAC_SHA256:
+		sha256_digest(mes, len, digest);
+		break;
+	case KEYCHAIN_ALGO_HMAC_SHA384:
+#ifdef CRYPTO_OPENSSL
+		sha384_digest(mes, len, digest);
+#endif
+		break;
+	case KEYCHAIN_ALGO_HMAC_SHA512:
+#ifdef CRYPTO_OPENSSL
+		sha512_digest(mes, len, digest);
+#endif
+		break;
+	case KEYCHAIN_ALGO_NULL:
+	case KEYCHAIN_ALGO_MAX:
+	default:
+		/* no action */
+		break;
+	}
+}
+
+unsigned int ospf6_auth_len_get(struct ospf6_interface *oi)
+{
+	unsigned int at_len = 0;
+	char *keychain_name = NULL;
+	struct keychain *keychain = NULL;
+	struct key *key = NULL;
+
+	if (CHECK_FLAG(oi->at_data.flags, OSPF6_AUTH_TRAILER_KEYCHAIN)) {
+		if (CHECK_FLAG(oi->at_data.flags,
+			       OSPF6_AUTH_TRAILER_KEYCHAIN_VALID)) {
+			at_len = OSPF6_AUTH_HDR_MIN_SIZE
+				 + keychain_get_hash_len(oi->at_data.hash_algo);
+		} else {
+			keychain_name = oi->at_data.keychain;
+			keychain = keychain_lookup(keychain_name);
+			if (keychain) {
+				key = key_lookup_for_send(keychain);
+				if (key && key->string
+				    && key->hash_algo != KEYCHAIN_ALGO_NULL) {
+					at_len = OSPF6_AUTH_HDR_MIN_SIZE
+						 + keychain_get_hash_len(
+							   key->hash_algo);
+				}
+			}
+		}
+	} else if (CHECK_FLAG(oi->at_data.flags,
+			      OSPF6_AUTH_TRAILER_MANUAL_KEY)) {
+		at_len = OSPF6_AUTH_HDR_MIN_SIZE
+			 + keychain_get_hash_len(oi->at_data.hash_algo);
+	}
+
+	return at_len;
+}
+
+int ospf6_auth_validate_pkt(struct ospf6_interface *oi, unsigned int *pkt_len,
+			    struct ospf6_header *oh, unsigned int *at_len)
+{
+	struct ospf6_hello *hello = NULL;
+	struct ospf6_dbdesc *dbdesc = NULL;
+	struct ospf6_neighbor *on = NULL;
+	struct ospf6_auth_hdr ospf6_auth_info;
+	uint16_t hdr_len = 0;
+	uint32_t oh_seqnum_h = 0;
+	uint32_t oh_seqnum_l = 0;
+
+	on = ospf6_neighbor_lookup(oh->router_id, oi);
+	hdr_len = ntohs(oh->length);
+	if (*pkt_len < hdr_len) {
+		if (IS_OSPF6_DEBUG_AUTH_RX)
+			zlog_warn("RECV[%s] Wrong %s packet auth length",
+				  oi->interface->name,
+				  lookup_msg(ospf6_message_type_str, oh->type,
+					     NULL));
+		oi->at_data.rx_drop++;
+		return -1;
+	} else if (*pkt_len == hdr_len) {
+		/* no auth data in packet
+		 */
+		return -1;
+	}
+
+	switch (oh->type) {
+	case OSPF6_MESSAGE_TYPE_HELLO:
+		hello = (struct ospf6_hello *)((uint8_t *)oh
+					       + sizeof(struct ospf6_header));
+		if (OSPF6_OPT_ISSET_EXT(hello->options, OSPF6_OPT_AT)) {
+			if (on)
+				on->auth_present = true;
+		} else {
+			if (on)
+				on->auth_present = false;
+
+			if (oi->at_data.flags != 0) {
+				if (IS_OSPF6_DEBUG_AUTH_RX)
+					zlog_warn("RECV[%s] : Auth option miss-match in hello pkt",
+						  oi->interface->name);
+				oi->at_data.rx_drop++;
+			}
+
+			return -1;
+		}
+		break;
+	case OSPF6_MESSAGE_TYPE_DBDESC:
+		dbdesc = (struct ospf6_dbdesc *)((uint8_t *)oh
+						 + sizeof(struct ospf6_header));
+
+		if (OSPF6_OPT_ISSET_EXT(dbdesc->options, OSPF6_OPT_AT)) {
+			if (on)
+				on->auth_present = true;
+		} else {
+			if (on)
+				on->auth_present = false;
+
+			if (oi->at_data.flags != 0) {
+				if (IS_OSPF6_DEBUG_AUTH_RX)
+					zlog_warn("RECV[%s] : Auth option miss-match in DB desc pkt",
+						  oi->interface->name);
+				oi->at_data.rx_drop++;
+			}
+
+			return -1;
+		}
+		break;
+	case OSPF6_MESSAGE_TYPE_LSREQ:
+	case OSPF6_MESSAGE_TYPE_LSUPDATE:
+	case OSPF6_MESSAGE_TYPE_LSACK:
+		if ((on && on->auth_present == false)
+		    && (oi->at_data.flags != 0)) {
+			if (IS_OSPF6_DEBUG_AUTH_RX)
+				zlog_warn("RECV[%s] : Auth config miss-match in %s",
+					  oi->interface->name,
+					  lookup_msg(ospf6_message_type_str,
+						     oh->type, NULL));
+			oi->at_data.rx_drop++;
+			return -1;
+		}
+		break;
+	default:
+		if (IS_OSPF6_DEBUG_AUTH_RX)
+			zlog_warn("RECV[%s] : Wrong packet type %d",
+				  oi->interface->name, oh->type);
+		return -1;
+	}
+
+	memset(&ospf6_auth_info, 0, sizeof(struct ospf6_auth_hdr));
+	memcpy(&ospf6_auth_info, (uint8_t *)oh + hdr_len, *pkt_len - hdr_len);
+	if (ntohs(ospf6_auth_info.length) > OSPF6_AUTH_HDR_FULL) {
+		if (IS_OSPF6_DEBUG_AUTH_RX)
+			zlog_warn("RECV[%s] : Auth config miss-match in %s",
+				  oi->interface->name,
+				  lookup_msg(ospf6_message_type_str, oh->type,
+					     NULL));
+		oi->at_data.rx_drop++;
+		return -1;
+	}
+
+	/* after authentication header validation is done
+	 * reduce the auth hdr size from the packet length
+	 */
+	*at_len = ntohs(ospf6_auth_info.length);
+	*pkt_len = *pkt_len - *at_len;
+
+	if (on) {
+		oh_seqnum_h = ntohl(ospf6_auth_info.seqnum_h);
+		oh_seqnum_l = ntohl(ospf6_auth_info.seqnum_l);
+		if ((oh_seqnum_h >= on->seqnum_h) &&
+		     (oh_seqnum_l > on->seqnum_l)) {
+			/* valid sequence number received */
+			on->seqnum_h = oh_seqnum_h;
+			on->seqnum_l = oh_seqnum_l;
+		} else {
+			if (IS_OSPF6_DEBUG_AUTH_RX) {
+				zlog_warn("RECV[%s] : Nbr(%s) Auth Sequence number mismatch",
+					  oi->interface->name, on->name);
+				zlog_warn("nbr_seq_l %u, nbr_seq_h %u, hdr_seq_l %u, hdr_seq_h %u",
+					  on->seqnum_l, on->seqnum_h,
+					  oh_seqnum_l, oh_seqnum_h);
+			}
+
+			oi->at_data.rx_drop++;
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+/* Starting point of packet process function. */
+int ospf6_auth_check_digest(struct ospf6_header *oh, struct ospf6_interface *oi,
+			    struct in6_addr *src)
+{
+	uint32_t hash_len = KEYCHAIN_MAX_HASH_SIZE;
+	unsigned char apad[hash_len];
+	unsigned char temp_hash[hash_len];
+	struct ospf6_auth_hdr *ospf6_auth;
+	uint32_t ipv6_addr_size = sizeof(struct in6_addr);
+	struct keychain *keychain = NULL;
+	struct key *key = NULL;
+	char *auth_str = NULL;
+	uint16_t auth_len = 0;
+	uint8_t hash_algo = 0;
+	uint16_t oh_len = ntohs(oh->length);
+
+	if (oi->at_data.flags == 0)
+		return -2;
+
+	ospf6_auth = (struct ospf6_auth_hdr *)((uint8_t *)oh + oh_len);
+	if (CHECK_FLAG(oi->at_data.flags, OSPF6_AUTH_TRAILER_KEYCHAIN)) {
+		keychain = keychain_lookup(oi->at_data.keychain);
+		if (!keychain) {
+			if (IS_OSPF6_DEBUG_AUTH_RX)
+				zlog_warn("RECV[%s]: Keychain does't exist for %s",
+					  oi->interface->name,
+					  lookup_msg(ospf6_message_type_str,
+						     oh->type, NULL));
+			oi->at_data.rx_drop++;
+			return -1;
+		}
+
+		key = key_lookup_for_accept(keychain, ntohs(ospf6_auth->id));
+		if (!key) {
+			if (IS_OSPF6_DEBUG_AUTH_RX)
+				zlog_warn("RECV[%s]: Auth, Invalid SA for %s",
+					  oi->interface->name,
+					  lookup_msg(ospf6_message_type_str,
+						     oh->type, NULL));
+			oi->at_data.rx_drop++;
+			return -1;
+		}
+
+		if (key && key->string
+		    && key->hash_algo != KEYCHAIN_ALGO_NULL) {
+			auth_str = key->string;
+			hash_algo = key->hash_algo;
+		} else {
+			if (IS_OSPF6_DEBUG_AUTH_RX)
+				zlog_warn("RECV[%s]: Incomplete keychain config for %s",
+					  oi->interface->name,
+					  lookup_msg(ospf6_message_type_str,
+						     oh->type, NULL));
+			oi->at_data.rx_drop++;
+			return -1;
+		}
+	} else if (CHECK_FLAG(oi->at_data.flags,
+			      OSPF6_AUTH_TRAILER_MANUAL_KEY)) {
+		auth_str = oi->at_data.auth_key;
+		hash_algo = oi->at_data.hash_algo;
+	}
+
+	if (!auth_str)
+		return -2;
+
+	hash_len = keychain_get_hash_len(hash_algo);
+	memset(apad, 0, sizeof(hash_len));
+	memset(temp_hash, 0, sizeof(hash_len));
+
+	/* start digest verification */
+	memcpy(apad, src, ipv6_addr_size);
+	memcpy(apad + ipv6_addr_size, ospf6_hash_apad_max,
+	       (hash_len - ipv6_addr_size));
+
+	auth_len = ntohs(ospf6_auth->length);
+
+	memcpy(temp_hash, ospf6_auth->data, hash_len);
+	memcpy(ospf6_auth->data, apad, hash_len);
+
+	ospf6_auth_update_digest(oi, oh, ospf6_auth, auth_str, auth_len,
+				 (oh_len + auth_len), hash_algo);
+
+#ifdef CRYPTO_OPENSSL
+	return !(CRYPTO_memcmp(temp_hash, ospf6_auth->data, hash_len));
+#else
+	return !(memcmp(temp_hash, ospf6_auth->data, hash_len));
+#endif
+}
+
+void ospf6_auth_digest_send(struct in6_addr *src, struct ospf6_interface *oi,
+			    struct ospf6_header *oh, uint16_t auth_len,
+			    uint32_t pkt_len)
+{
+	struct ospf6_auth_hdr *ospf6_auth;
+	char *keychain_name = NULL;
+	struct keychain *keychain = NULL;
+	struct key *key = NULL;
+	char *auth_str = NULL;
+	uint16_t key_id = 0;
+	enum keychain_hash_algo hash_algo = KEYCHAIN_ALGO_NULL;
+	uint32_t hash_len = KEYCHAIN_MAX_HASH_SIZE;
+	unsigned char apad[hash_len];
+	int ipv6_addr_size = sizeof(struct in6_addr);
+
+	if (CHECK_FLAG(oi->at_data.flags, OSPF6_AUTH_TRAILER_KEYCHAIN)) {
+		if (CHECK_FLAG(oi->at_data.flags,
+			       OSPF6_AUTH_TRAILER_KEYCHAIN_VALID)) {
+			auth_str = oi->at_data.auth_key;
+			hash_algo = oi->at_data.hash_algo;
+			key_id = oi->at_data.key_id;
+		} else {
+			keychain_name = oi->at_data.keychain;
+			keychain = keychain_lookup(keychain_name);
+			if (keychain) {
+				key = key_lookup_for_send(keychain);
+				if (key && key->string
+				    && key->hash_algo != KEYCHAIN_ALGO_NULL) {
+					auth_str = key->string;
+					hash_algo = key->hash_algo;
+					key_id = key->index;
+				}
+			}
+		}
+	} else if (CHECK_FLAG(oi->at_data.flags,
+			      OSPF6_AUTH_TRAILER_MANUAL_KEY)) {
+		auth_str = oi->at_data.auth_key;
+		hash_algo = oi->at_data.hash_algo;
+		key_id = oi->at_data.key_id;
+	} else {
+		if (IS_OSPF6_DEBUG_AUTH_TX)
+			zlog_warn("SEND[%s]: Authentication not configured for %s",
+				  oi->interface->name,
+				  lookup_msg(ospf6_message_type_str,
+					     oh->type, NULL));
+		return;
+	}
+
+	if (!auth_str) {
+		if (IS_OSPF6_DEBUG_AUTH_TX)
+			zlog_warn("SEND[%s]: Authentication key is not configured for %s",
+				  oi->interface->name,
+				  lookup_msg(ospf6_message_type_str,
+					     oh->type, NULL));
+		return;
+	}
+
+	hash_len = keychain_get_hash_len(hash_algo);
+	oi->at_data.seqnum_l++;
+
+	if (oi->at_data.seqnum_l == 0xFFFFFFFF) {
+		oi->at_data.seqnum_h++;
+		oi->at_data.seqnum_l = 0;
+	}
+
+	/* Key must be reset. which is not handled as of now. */
+	if ((oi->at_data.seqnum_l == 0xFFFFFFFF)
+	    && (oi->at_data.seqnum_h == 0xFFFFFFFF)) {
+		oi->at_data.seqnum_l = 0;
+		oi->at_data.seqnum_h = 0;
+	}
+
+	memset(apad, 0, hash_len);
+
+	if (src)
+		memcpy(apad, src, ipv6_addr_size);
+
+	memcpy(apad + ipv6_addr_size, ospf6_hash_apad_max,
+	       (hash_len - ipv6_addr_size));
+
+	ospf6_auth =
+		(struct ospf6_auth_hdr *)((uint8_t *)oh + ntohs(oh->length));
+	ospf6_auth->type = htons(OSPF6_AUTHENTICATION_CRYPTOGRAPHIC);
+	ospf6_auth->length = htons(auth_len);
+	ospf6_auth->reserved = 0;
+	ospf6_auth->id = htons(key_id);
+	ospf6_auth->seqnum_h = htonl(oi->at_data.seqnum_h);
+	ospf6_auth->seqnum_l = htonl(oi->at_data.seqnum_l);
+	memcpy(ospf6_auth->data, apad, hash_len);
+
+	ospf6_auth_update_digest(oi, oh, ospf6_auth, auth_str, auth_len,
+				 pkt_len, hash_algo);
+
+	if (CHECK_FLAG(oi->at_data.flags, OSPF6_AUTH_TRAILER_KEYCHAIN_VALID)) {
+		oi->at_data.hash_algo = KEYCHAIN_ALGO_NULL;
+		if (oi->at_data.auth_key) {
+			XFREE(MTYPE_OSPF6_AUTH_MANUAL_KEY,
+			      oi->at_data.auth_key);
+			oi->at_data.auth_key = NULL;
+		}
+
+		oi->at_data.key_id = 0;
+		UNSET_FLAG(oi->at_data.flags,
+			   OSPF6_AUTH_TRAILER_KEYCHAIN_VALID);
+	}
+}
+
+void ospf6_auth_update_digest(struct ospf6_interface *oi,
+			      struct ospf6_header *oh,
+			      struct ospf6_auth_hdr *ospf6_auth, char *auth_str,
+			      uint16_t auth_len, uint32_t pkt_len,
+			      enum keychain_hash_algo algo)
+{
+	uint32_t hash_len = keychain_get_hash_len(algo);
+	uint32_t block_s = keychain_get_block_size(algo);
+	uint32_t k_len = strlen(auth_str);
+	uint32_t ks_len = strlen(auth_str) + sizeof(CPID);
+	unsigned char ipad[block_s];
+	unsigned char opad[block_s];
+	unsigned char ko[block_s], ks[ks_len], tmp[hash_len];
+	unsigned char *first = NULL;
+	unsigned char *second = NULL;
+	unsigned char *first_mes, *second_mes;
+	unsigned char *first_hash, *second_hash;
+
+	memset(ko, 0, block_s);
+	memcpy(ks, auth_str, k_len);
+	memcpy(ks + k_len, &CPID, sizeof(CPID));
+	if (ks_len > hash_len) {
+		ospf6_hash_hmac_sha_digest(algo, ks, ks_len, tmp);
+		memcpy(ko, tmp, hash_len);
+	} else
+		memcpy(ko, ks, ks_len);
+
+	memcpy(ipad, ospf6_hash_ipad_max, block_s);
+	memcpy(opad, ospf6_hash_opad_max, block_s);
+
+	first = ospf6_hash_message_xor((unsigned char *)&ipad, ko, block_s);
+	second = ospf6_hash_message_xor((unsigned char *)&opad, ko, block_s);
+
+	first_mes = XMALLOC(MTYPE_OSPF6_AUTH_PKT, (block_s + pkt_len));
+
+	memcpy(first_mes, first, block_s);
+	memcpy(first_mes + block_s, oh, pkt_len);
+
+	first_hash = XMALLOC(MTYPE_OSPF6_AUTH_HASH, hash_len);
+
+	ospf6_hash_hmac_sha_digest(algo, first_mes, (block_s + pkt_len),
+				   first_hash);
+
+	second_mes = XMALLOC(MTYPE_OSPF6_AUTH_PKT, (block_s + hash_len));
+
+	memcpy(second_mes, second, block_s);
+	memcpy(second_mes + block_s, first_hash, hash_len);
+
+	second_hash = XMALLOC(MTYPE_OSPF6_AUTH_HASH, hash_len);
+
+	ospf6_hash_hmac_sha_digest(algo, second_mes, (block_s + hash_len),
+				   second_hash);
+
+	memcpy(ospf6_auth->data, second_hash, hash_len);
+	XFREE(MTYPE_OSPF6_AUTH_PKT, first_mes);
+	XFREE(MTYPE_OSPF6_AUTH_PKT, second_mes);
+	XFREE(MTYPE_OSPF6_AUTH_HASH, first_hash);
+	XFREE(MTYPE_OSPF6_AUTH_HASH, second_hash);
+	XFREE(MTYPE_OSPF6_AUTH_HASH_XOR, first);
+	XFREE(MTYPE_OSPF6_AUTH_HASH_XOR, second);
+}
+
+DEFUN (debug_ospf6_auth,
+       debug_ospf6_auth_cmd,
+       "debug ospf6 authentication [<tx|rx>]",
+       DEBUG_STR
+       OSPF6_STR
+       "debug OSPF6 authentication\n"
+       "debug authentication tx\n"
+       "debug authentication rx\n")
+{
+	int auth_opt_idx = 3;
+
+	if (argc == 4) {
+		if (!strncmp(argv[auth_opt_idx]->arg, "t", 1))
+			OSPF6_DEBUG_AUTH_TX_ON();
+		else if (!strncmp(argv[auth_opt_idx]->arg, "r", 1))
+			OSPF6_DEBUG_AUTH_RX_ON();
+	} else {
+		OSPF6_DEBUG_AUTH_TX_ON();
+		OSPF6_DEBUG_AUTH_RX_ON();
+	}
+
+	return CMD_SUCCESS;
+}
+
+DEFUN (no_debug_ospf6_auth,
+       no_debug_ospf6_auth_cmd,
+       "no debug ospf6 authentication [<tx|rx>]",
+       NO_STR
+       DEBUG_STR
+       OSPF6_STR
+       "debug OSPF6 authentication\n"
+       "debug authentication tx\n"
+       "debug authentication rx\n")
+{
+	int auth_opt_idx = 3;
+
+	if (argc == 5) {
+		if (!strncmp(argv[auth_opt_idx]->arg, "t", 1))
+			OSPF6_DEBUG_AUTH_TX_OFF();
+		else if (!strncmp(argv[auth_opt_idx]->arg, "r", 1))
+			OSPF6_DEBUG_AUTH_RX_OFF();
+	} else {
+		OSPF6_DEBUG_AUTH_TX_OFF();
+		OSPF6_DEBUG_AUTH_RX_OFF();
+	}
+
+	return CMD_SUCCESS;
+}
+
+int config_write_ospf6_debug_auth(struct vty *vty)
+{
+	if (IS_OSPF6_DEBUG_AUTH_TX)
+		vty_out(vty, "debug ospf6 authentication tx\n");
+	if (IS_OSPF6_DEBUG_AUTH_RX)
+		vty_out(vty, "debug ospf6 authentication rx\n");
+	return 0;
+}
+
+void install_element_ospf6_debug_auth(void)
+{
+	install_element(ENABLE_NODE, &debug_ospf6_auth_cmd);
+	install_element(ENABLE_NODE, &no_debug_ospf6_auth_cmd);
+	install_element(CONFIG_NODE, &debug_ospf6_auth_cmd);
+	install_element(CONFIG_NODE, &no_debug_ospf6_auth_cmd);
+}
+
+/* Clear the specified interface structure */
+static void ospf6_intf_auth_clear(struct vty *vty, struct interface *ifp)
+{
+	struct ospf6_interface *oi;
+
+	if (!if_is_operative(ifp))
+		return;
+
+	if (ifp->info == NULL)
+		return;
+
+	oi = (struct ospf6_interface *)ifp->info;
+
+	if (IS_OSPF6_DEBUG_INTERFACE)
+		zlog_debug(
+			"Interface %s: clear authentication rx/tx drop counters",
+			ifp->name);
+
+	/* Reset the interface rx/tx drop counters */
+	oi->at_data.tx_drop = 0;
+	oi->at_data.rx_drop = 0;
+}
+
+/* Clear interface */
+DEFUN(clear_ipv6_ospf6_intf_auth,
+      clear_ipv6_ospf6_intf_auth_cmd,
+      "clear ipv6 ospf6 auth-counters interface [IFNAME]",
+      CLEAR_STR
+      IP6_STR
+      OSPF6_STR
+      "authentication rx/tx drop counters\n"
+      INTERFACE_STR
+      IFNAME_STR)
+{
+	struct vrf *vrf = vrf_lookup_by_id(VRF_DEFAULT);
+	int idx_ifname = 5;
+	struct interface *ifp;
+
+	if (argc == 5) { /* Clear all the ospfv3 interfaces. */
+		FOR_ALL_INTERFACES (vrf, ifp)
+			ospf6_intf_auth_clear(vty, ifp);
+	} else { /* Interface name is specified. */
+		ifp = if_lookup_by_name(argv[idx_ifname]->arg, VRF_DEFAULT);
+		if (ifp  == NULL) {
+			vty_out(vty, "Error: No such Interface: %s\n",
+				argv[idx_ifname]->arg);
+			return CMD_WARNING;
+		}
+		ospf6_intf_auth_clear(vty, ifp);
+	}
+
+	return CMD_SUCCESS;
+}
+
+void install_element_ospf6_clear_intf_auth(void)
+{
+	install_element(ENABLE_NODE, &clear_ipv6_ospf6_intf_auth_cmd);
+}
diff --git a/ospf6d/ospf6_auth_trailer.h b/ospf6d/ospf6_auth_trailer.h
new file mode 100644
index 000000000..fa2de28ef
--- /dev/null
+++ b/ospf6d/ospf6_auth_trailer.h
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2021 Abhinay Ramesh
+ *
+ * This file is part of GNU Zebra.
+ *
+ * GNU Zebra is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * GNU Zebra is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef __OSPF6_AUTH_TRAILER_H__
+#define __OSPF6_AUTH_TRAILER_H__
+
+#include "lib/keychain.h"
+#include "ospf6_message.h"
+
+#define OSPF6_AUTH_HDR_MIN_SIZE 16
+#define OSPF6_AUTH_HDR_FULL     KEYCHAIN_MAX_HASH_SIZE + OSPF6_AUTH_HDR_MIN_SIZE
+
+#define OSPF6_AUTHENTICATION_NULL                 0
+#define OSPF6_AUTHENTICATION_CRYPTOGRAPHIC        1
+static const uint16_t CPID = 1;
+
+/* Auth debug options */
+extern unsigned char conf_debug_ospf6_auth[2];
+#define OSPF6_AUTH_TX 0
+#define OSPF6_AUTH_RX 1
+#define OSPF6_DEBUG_AUTH_TX_ON() (conf_debug_ospf6_auth[OSPF6_AUTH_TX] = 1)
+#define OSPF6_DEBUG_AUTH_TX_OFF() (conf_debug_ospf6_auth[OSPF6_AUTH_TX] = 0)
+#define OSPF6_DEBUG_AUTH_RX_ON() (conf_debug_ospf6_auth[OSPF6_AUTH_RX] = 1)
+#define OSPF6_DEBUG_AUTH_RX_OFF() (conf_debug_ospf6_auth[OSPF6_AUTH_RX] = 0)
+#define IS_OSPF6_DEBUG_AUTH_TX (conf_debug_ospf6_auth[OSPF6_AUTH_TX])
+#define IS_OSPF6_DEBUG_AUTH_RX (conf_debug_ospf6_auth[OSPF6_AUTH_RX])
+
+#define OSPF6_AUTH_TRAILER_KEYCHAIN (1 << 0)
+#define OSPF6_AUTH_TRAILER_MANUAL_KEY (1 << 1)
+#define OSPF6_AUTH_TRAILER_KEYCHAIN_VALID (1 << 2)
+
+/* According to sesion 4.1 of RFC7166 defining the trailer struct */
+struct ospf6_auth_hdr {
+	uint16_t type;
+	uint16_t length;
+	uint16_t reserved;
+	uint16_t id;
+	uint32_t seqnum_h;
+	uint32_t seqnum_l;
+	unsigned char data[KEYCHAIN_MAX_HASH_SIZE];
+};
+
+void ospf6_auth_hdr_dump_send(struct ospf6_header *ospfh, uint16_t length);
+void ospf6_auth_hdr_dump_recv(struct ospf6_header *ospfh, uint16_t length);
+unsigned char *ospf6_hash_message_xor(unsigned char *mes1, unsigned char *mes2,
+				      uint32_t len);
+unsigned int ospf6_auth_len_get(struct ospf6_interface *oi);
+int ospf6_auth_validate_pkt(struct ospf6_interface *oi, unsigned int *pkt_len,
+			    struct ospf6_header *oh, unsigned int *at_len);
+int ospf6_auth_check_digest(struct ospf6_header *oh, struct ospf6_interface *oi,
+			    struct in6_addr *src);
+void ospf6_auth_update_digest(struct ospf6_interface *oi,
+			      struct ospf6_header *oh,
+			      struct ospf6_auth_hdr *ospf6_auth, char *auth_str,
+			      uint16_t auth_len, uint32_t pkt_len,
+			      enum keychain_hash_algo algo);
+void ospf6_auth_digest_send(struct in6_addr *src, struct ospf6_interface *oi,
+			    struct ospf6_header *oh, uint16_t auth_len,
+			    uint32_t pkt_len);
+void install_element_ospf6_debug_auth(void);
+int config_write_ospf6_debug_auth(struct vty *vty);
+void install_element_ospf6_clear_intf_auth(void);
+#endif /* __OSPF6_AUTH_TRAILER_H__ */
diff --git a/ospf6d/ospf6_interface.h b/ospf6d/ospf6_interface.h
index d068a9857..d6a2b52e1 100644
--- a/ospf6d/ospf6_interface.h
+++ b/ospf6d/ospf6_interface.h
@@ -26,6 +26,8 @@
 #include "if.h"
 #include "ospf6d.h"
 
+DECLARE_MTYPE(OSPF6_AUTH_MANUAL_KEY);
+
 /* Debug option */
 extern unsigned char conf_debug_ospf6_interface;
 #define OSPF6_DEBUG_INTERFACE_ON() (conf_debug_ospf6_interface = 1)
diff --git a/ospf6d/ospf6_message.h b/ospf6d/ospf6_message.h
index 0cd10ef82..68cb4c779 100644
--- a/ospf6d/ospf6_message.h
+++ b/ospf6d/ospf6_message.h
@@ -23,6 +23,8 @@
 
 #define OSPF6_MESSAGE_BUFSIZ  4096
 
+extern const struct message ospf6_message_type_str[];
+
 /* Debug option */
 extern unsigned char conf_debug_ospf6_message[];
 #define OSPF6_ACTION_SEND 0x01