Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 807 insertions, 0 deletions

diff --git a/net/ipv6/ah6.c b/net/ipv6/ah6.c
new file mode 100644
index 000000000..5228d2716
--- /dev/null
+++ b/net/ipv6/ah6.c
@@ -0,0 +1,807 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C)2002 USAGI/WIDE Project
+ *
+ * Authors
+ *
+ *	Mitsuru KANDA @USAGI       : IPv6 Support
+ *	Kazunori MIYAZAWA @USAGI   :
+ *	Kunihiro Ishiguro <kunihiro@ipinfusion.com>
+ *
+ *	This file is derived from net/ipv4/ah.c.
+ */
+
+#define pr_fmt(fmt) "IPv6: " fmt
+
+#include <crypto/algapi.h>
+#include <crypto/hash.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <net/ip.h>
+#include <net/ah.h>
+#include <linux/crypto.h>
+#include <linux/pfkeyv2.h>
+#include <linux/string.h>
+#include <linux/scatterlist.h>
+#include <net/ip6_route.h>
+#include <net/icmp.h>
+#include <net/ipv6.h>
+#include <net/protocol.h>
+#include <net/xfrm.h>
+
+#define IPV6HDR_BASELEN 8
+
+struct tmp_ext {
+#if IS_ENABLED(CONFIG_IPV6_MIP6)
+		struct in6_addr saddr;
+#endif
+		struct in6_addr daddr;
+		char hdrs[];
+};
+
+struct ah_skb_cb {
+	struct xfrm_skb_cb xfrm;
+	void *tmp;
+};
+
+#define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
+
+static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
+			  unsigned int size)
+{
+	unsigned int len;
+
+	len = size + crypto_ahash_digestsize(ahash) +
+	      (crypto_ahash_alignmask(ahash) &
+	       ~(crypto_tfm_ctx_alignment() - 1));
+
+	len = ALIGN(len, crypto_tfm_ctx_alignment());
+
+	len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
+	len = ALIGN(len, __alignof__(struct scatterlist));
+
+	len += sizeof(struct scatterlist) * nfrags;
+
+	return kmalloc(len, GFP_ATOMIC);
+}
+
+static inline struct tmp_ext *ah_tmp_ext(void *base)
+{
+	return base + IPV6HDR_BASELEN;
+}
+
+static inline u8 *ah_tmp_auth(u8 *tmp, unsigned int offset)
+{
+	return tmp + offset;
+}
+
+static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
+			     unsigned int offset)
+{
+	return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
+}
+
+static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
+					       u8 *icv)
+{
+	struct ahash_request *req;
+
+	req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
+				crypto_tfm_ctx_alignment());
+
+	ahash_request_set_tfm(req, ahash);
+
+	return req;
+}
+
+static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
+					     struct ahash_request *req)
+{
+	return (void *)ALIGN((unsigned long)(req + 1) +
+			     crypto_ahash_reqsize(ahash),
+			     __alignof__(struct scatterlist));
+}
+
+static bool zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
+{
+	u8 *opt = (u8 *)opthdr;
+	int len = ipv6_optlen(opthdr);
+	int off = 0;
+	int optlen = 0;
+
+	off += 2;
+	len -= 2;
+
+	while (len > 0) {
+
+		switch (opt[off]) {
+
+		case IPV6_TLV_PAD1:
+			optlen = 1;
+			break;
+		default:
+			if (len < 2)
+				goto bad;
+			optlen = opt[off+1]+2;
+			if (len < optlen)
+				goto bad;
+			if (opt[off] & 0x20)
+				memset(&opt[off+2], 0, opt[off+1]);
+			break;
+		}
+
+		off += optlen;
+		len -= optlen;
+	}
+	if (len == 0)
+		return true;
+
+bad:
+	return false;
+}
+
+#if IS_ENABLED(CONFIG_IPV6_MIP6)
+/**
+ *	ipv6_rearrange_destopt - rearrange IPv6 destination options header
+ *	@iph: IPv6 header
+ *	@destopt: destionation options header
+ */
+static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt)
+{
+	u8 *opt = (u8 *)destopt;
+	int len = ipv6_optlen(destopt);
+	int off = 0;
+	int optlen = 0;
+
+	off += 2;
+	len -= 2;
+
+	while (len > 0) {
+
+		switch (opt[off]) {
+
+		case IPV6_TLV_PAD1:
+			optlen = 1;
+			break;
+		default:
+			if (len < 2)
+				goto bad;
+			optlen = opt[off+1]+2;
+			if (len < optlen)
+				goto bad;
+
+			/* Rearrange the source address in @iph and the
+			 * addresses in home address option for final source.
+			 * See 11.3.2 of RFC 3775 for details.
+			 */
+			if (opt[off] == IPV6_TLV_HAO) {
+				struct ipv6_destopt_hao *hao;
+
+				hao = (struct ipv6_destopt_hao *)&opt[off];
+				if (hao->length != sizeof(hao->addr)) {
+					net_warn_ratelimited("destopt hao: invalid header length: %u\n",
+							     hao->length);
+					goto bad;
+				}
+				swap(hao->addr, iph->saddr);
+			}
+			break;
+		}
+
+		off += optlen;
+		len -= optlen;
+	}
+	/* Note: ok if len == 0 */
+bad:
+	return;
+}
+#else
+static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt) {}
+#endif
+
+/**
+ *	ipv6_rearrange_rthdr - rearrange IPv6 routing header
+ *	@iph: IPv6 header
+ *	@rthdr: routing header
+ *
+ *	Rearrange the destination address in @iph and the addresses in @rthdr
+ *	so that they appear in the order they will at the final destination.
+ *	See Appendix A2 of RFC 2402 for details.
+ */
+static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
+{
+	int segments, segments_left;
+	struct in6_addr *addrs;
+	struct in6_addr final_addr;
+
+	segments_left = rthdr->segments_left;
+	if (segments_left == 0)
+		return;
+	rthdr->segments_left = 0;
+
+	/* The value of rthdr->hdrlen has been verified either by the system
+	 * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
+	 * packets.  So we can assume that it is even and that segments is
+	 * greater than or equal to segments_left.
+	 *
+	 * For the same reason we can assume that this option is of type 0.
+	 */
+	segments = rthdr->hdrlen >> 1;
+
+	addrs = ((struct rt0_hdr *)rthdr)->addr;
+	final_addr = addrs[segments - 1];
+
+	addrs += segments - segments_left;
+	memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
+
+	addrs[0] = iph->daddr;
+	iph->daddr = final_addr;
+}
+
+static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len, int dir)
+{
+	union {
+		struct ipv6hdr *iph;
+		struct ipv6_opt_hdr *opth;
+		struct ipv6_rt_hdr *rth;
+		char *raw;
+	} exthdr = { .iph = iph };
+	char *end = exthdr.raw + len;
+	int nexthdr = iph->nexthdr;
+
+	exthdr.iph++;
+
+	while (exthdr.raw < end) {
+		switch (nexthdr) {
+		case NEXTHDR_DEST:
+			if (dir == XFRM_POLICY_OUT)
+				ipv6_rearrange_destopt(iph, exthdr.opth);
+			fallthrough;
+		case NEXTHDR_HOP:
+			if (!zero_out_mutable_opts(exthdr.opth)) {
+				net_dbg_ratelimited("overrun %sopts\n",
+						    nexthdr == NEXTHDR_HOP ?
+						    "hop" : "dest");
+				return -EINVAL;
+			}
+			break;
+
+		case NEXTHDR_ROUTING:
+			ipv6_rearrange_rthdr(iph, exthdr.rth);
+			break;
+
+		default:
+			return 0;
+		}
+
+		nexthdr = exthdr.opth->nexthdr;
+		exthdr.raw += ipv6_optlen(exthdr.opth);
+	}
+
+	return 0;
+}
+
+static void ah6_output_done(struct crypto_async_request *base, int err)
+{
+	int extlen;
+	u8 *iph_base;
+	u8 *icv;
+	struct sk_buff *skb = base->data;
+	struct xfrm_state *x = skb_dst(skb)->xfrm;
+	struct ah_data *ahp = x->data;
+	struct ipv6hdr *top_iph = ipv6_hdr(skb);
+	struct ip_auth_hdr *ah = ip_auth_hdr(skb);
+	struct tmp_ext *iph_ext;
+
+	extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
+	if (extlen)
+		extlen += sizeof(*iph_ext);
+
+	iph_base = AH_SKB_CB(skb)->tmp;
+	iph_ext = ah_tmp_ext(iph_base);
+	icv = ah_tmp_icv(ahp->ahash, iph_ext, extlen);
+
+	memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
+	memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
+
+	if (extlen) {
+#if IS_ENABLED(CONFIG_IPV6_MIP6)
+		memcpy(&top_iph->saddr, iph_ext, extlen);
+#else
+		memcpy(&top_iph->daddr, iph_ext, extlen);
+#endif
+	}
+
+	kfree(AH_SKB_CB(skb)->tmp);
+	xfrm_output_resume(skb->sk, skb, err);
+}
+
+static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err;
+	int nfrags;
+	int extlen;
+	u8 *iph_base;
+	u8 *icv;
+	u8 nexthdr;
+	struct sk_buff *trailer;
+	struct crypto_ahash *ahash;
+	struct ahash_request *req;
+	struct scatterlist *sg;
+	struct ipv6hdr *top_iph;
+	struct ip_auth_hdr *ah;
+	struct ah_data *ahp;
+	struct tmp_ext *iph_ext;
+	int seqhi_len = 0;
+	__be32 *seqhi;
+	int sglists = 0;
+	struct scatterlist *seqhisg;
+
+	ahp = x->data;
+	ahash = ahp->ahash;
+
+	err = skb_cow_data(skb, 0, &trailer);
+	if (err < 0)
+		goto out;
+	nfrags = err;
+
+	skb_push(skb, -skb_network_offset(skb));
+	extlen = skb_network_header_len(skb) - sizeof(struct ipv6hdr);
+	if (extlen)
+		extlen += sizeof(*iph_ext);
+
+	if (x->props.flags & XFRM_STATE_ESN) {
+		sglists = 1;
+		seqhi_len = sizeof(*seqhi);
+	}
+	err = -ENOMEM;
+	iph_base = ah_alloc_tmp(ahash, nfrags + sglists, IPV6HDR_BASELEN +
+				extlen + seqhi_len);
+	if (!iph_base)
+		goto out;
+
+	iph_ext = ah_tmp_ext(iph_base);
+	seqhi = (__be32 *)((char *)iph_ext + extlen);
+	icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
+	req = ah_tmp_req(ahash, icv);
+	sg = ah_req_sg(ahash, req);
+	seqhisg = sg + nfrags;
+
+	ah = ip_auth_hdr(skb);
+	memset(ah->auth_data, 0, ahp->icv_trunc_len);
+
+	top_iph = ipv6_hdr(skb);
+	top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
+
+	nexthdr = *skb_mac_header(skb);
+	*skb_mac_header(skb) = IPPROTO_AH;
+
+	/* When there are no extension headers, we only need to save the first
+	 * 8 bytes of the base IP header.
+	 */
+	memcpy(iph_base, top_iph, IPV6HDR_BASELEN);
+
+	if (extlen) {
+#if IS_ENABLED(CONFIG_IPV6_MIP6)
+		memcpy(iph_ext, &top_iph->saddr, extlen);
+#else
+		memcpy(iph_ext, &top_iph->daddr, extlen);
+#endif
+		err = ipv6_clear_mutable_options(top_iph,
+						 extlen - sizeof(*iph_ext) +
+						 sizeof(*top_iph),
+						 XFRM_POLICY_OUT);
+		if (err)
+			goto out_free;
+	}
+
+	ah->nexthdr = nexthdr;
+
+	top_iph->priority    = 0;
+	top_iph->flow_lbl[0] = 0;
+	top_iph->flow_lbl[1] = 0;
+	top_iph->flow_lbl[2] = 0;
+	top_iph->hop_limit   = 0;
+
+	ah->hdrlen  = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
+
+	ah->reserved = 0;
+	ah->spi = x->id.spi;
+	ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
+
+	sg_init_table(sg, nfrags + sglists);
+	err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
+	if (unlikely(err < 0))
+		goto out_free;
+
+	if (x->props.flags & XFRM_STATE_ESN) {
+		/* Attach seqhi sg right after packet payload */
+		*seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
+		sg_set_buf(seqhisg, seqhi, seqhi_len);
+	}
+	ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
+	ahash_request_set_callback(req, 0, ah6_output_done, skb);
+
+	AH_SKB_CB(skb)->tmp = iph_base;
+
+	err = crypto_ahash_digest(req);
+	if (err) {
+		if (err == -EINPROGRESS)
+			goto out;
+
+		if (err == -ENOSPC)
+			err = NET_XMIT_DROP;
+		goto out_free;
+	}
+
+	memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
+	memcpy(top_iph, iph_base, IPV6HDR_BASELEN);
+
+	if (extlen) {
+#if IS_ENABLED(CONFIG_IPV6_MIP6)
+		memcpy(&top_iph->saddr, iph_ext, extlen);
+#else
+		memcpy(&top_iph->daddr, iph_ext, extlen);
+#endif
+	}
+
+out_free:
+	kfree(iph_base);
+out:
+	return err;
+}
+
+static void ah6_input_done(struct crypto_async_request *base, int err)
+{
+	u8 *auth_data;
+	u8 *icv;
+	u8 *work_iph;
+	struct sk_buff *skb = base->data;
+	struct xfrm_state *x = xfrm_input_state(skb);
+	struct ah_data *ahp = x->data;
+	struct ip_auth_hdr *ah = ip_auth_hdr(skb);
+	int hdr_len = skb_network_header_len(skb);
+	int ah_hlen = ipv6_authlen(ah);
+
+	if (err)
+		goto out;
+
+	work_iph = AH_SKB_CB(skb)->tmp;
+	auth_data = ah_tmp_auth(work_iph, hdr_len);
+	icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
+
+	err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
+	if (err)
+		goto out;
+
+	err = ah->nexthdr;
+
+	skb->network_header += ah_hlen;
+	memcpy(skb_network_header(skb), work_iph, hdr_len);
+	__skb_pull(skb, ah_hlen + hdr_len);
+	if (x->props.mode == XFRM_MODE_TUNNEL)
+		skb_reset_transport_header(skb);
+	else
+		skb_set_transport_header(skb, -hdr_len);
+out:
+	kfree(AH_SKB_CB(skb)->tmp);
+	xfrm_input_resume(skb, err);
+}
+
+
+
+static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+	/*
+	 * Before process AH
+	 * [IPv6][Ext1][Ext2][AH][Dest][Payload]
+	 * |<-------------->| hdr_len
+	 *
+	 * To erase AH:
+	 * Keeping copy of cleared headers. After AH processing,
+	 * Moving the pointer of skb->network_header by using skb_pull as long
+	 * as AH header length. Then copy back the copy as long as hdr_len
+	 * If destination header following AH exists, copy it into after [Ext2].
+	 *
+	 * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
+	 * There is offset of AH before IPv6 header after the process.
+	 */
+
+	u8 *auth_data;
+	u8 *icv;
+	u8 *work_iph;
+	struct sk_buff *trailer;
+	struct crypto_ahash *ahash;
+	struct ahash_request *req;
+	struct scatterlist *sg;
+	struct ip_auth_hdr *ah;
+	struct ipv6hdr *ip6h;
+	struct ah_data *ahp;
+	u16 hdr_len;
+	u16 ah_hlen;
+	int nexthdr;
+	int nfrags;
+	int err = -ENOMEM;
+	int seqhi_len = 0;
+	__be32 *seqhi;
+	int sglists = 0;
+	struct scatterlist *seqhisg;
+
+	if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
+		goto out;
+
+	/* We are going to _remove_ AH header to keep sockets happy,
+	 * so... Later this can change. */
+	if (skb_unclone(skb, GFP_ATOMIC))
+		goto out;
+
+	skb->ip_summed = CHECKSUM_NONE;
+
+	hdr_len = skb_network_header_len(skb);
+	ah = (struct ip_auth_hdr *)skb->data;
+	ahp = x->data;
+	ahash = ahp->ahash;
+
+	nexthdr = ah->nexthdr;
+	ah_hlen = ipv6_authlen(ah);
+
+	if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
+	    ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
+		goto out;
+
+	if (!pskb_may_pull(skb, ah_hlen))
+		goto out;
+
+	err = skb_cow_data(skb, 0, &trailer);
+	if (err < 0)
+		goto out;
+	nfrags = err;
+
+	ah = (struct ip_auth_hdr *)skb->data;
+	ip6h = ipv6_hdr(skb);
+
+	skb_push(skb, hdr_len);
+
+	if (x->props.flags & XFRM_STATE_ESN) {
+		sglists = 1;
+		seqhi_len = sizeof(*seqhi);
+	}
+
+	work_iph = ah_alloc_tmp(ahash, nfrags + sglists, hdr_len +
+				ahp->icv_trunc_len + seqhi_len);
+	if (!work_iph) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	auth_data = ah_tmp_auth((u8 *)work_iph, hdr_len);
+	seqhi = (__be32 *)(auth_data + ahp->icv_trunc_len);
+	icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
+	req = ah_tmp_req(ahash, icv);
+	sg = ah_req_sg(ahash, req);
+	seqhisg = sg + nfrags;
+
+	memcpy(work_iph, ip6h, hdr_len);
+	memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
+	memset(ah->auth_data, 0, ahp->icv_trunc_len);
+
+	err = ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN);
+	if (err)
+		goto out_free;
+
+	ip6h->priority    = 0;
+	ip6h->flow_lbl[0] = 0;
+	ip6h->flow_lbl[1] = 0;
+	ip6h->flow_lbl[2] = 0;
+	ip6h->hop_limit   = 0;
+
+	sg_init_table(sg, nfrags + sglists);
+	err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
+	if (unlikely(err < 0))
+		goto out_free;
+
+	if (x->props.flags & XFRM_STATE_ESN) {
+		/* Attach seqhi sg right after packet payload */
+		*seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
+		sg_set_buf(seqhisg, seqhi, seqhi_len);
+	}
+
+	ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
+	ahash_request_set_callback(req, 0, ah6_input_done, skb);
+
+	AH_SKB_CB(skb)->tmp = work_iph;
+
+	err = crypto_ahash_digest(req);
+	if (err) {
+		if (err == -EINPROGRESS)
+			goto out;
+
+		goto out_free;
+	}
+
+	err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
+	if (err)
+		goto out_free;
+
+	skb->network_header += ah_hlen;
+	memcpy(skb_network_header(skb), work_iph, hdr_len);
+	__skb_pull(skb, ah_hlen + hdr_len);
+
+	if (x->props.mode == XFRM_MODE_TUNNEL)
+		skb_reset_transport_header(skb);
+	else
+		skb_set_transport_header(skb, -hdr_len);
+
+	err = nexthdr;
+
+out_free:
+	kfree(work_iph);
+out:
+	return err;
+}
+
+static int ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+		   u8 type, u8 code, int offset, __be32 info)
+{
+	struct net *net = dev_net(skb->dev);
+	struct ipv6hdr *iph = (struct ipv6hdr *)skb->data;
+	struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+offset);
+	struct xfrm_state *x;
+
+	if (type != ICMPV6_PKT_TOOBIG &&
+	    type != NDISC_REDIRECT)
+		return 0;
+
+	x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
+	if (!x)
+		return 0;
+
+	if (type == NDISC_REDIRECT)
+		ip6_redirect(skb, net, skb->dev->ifindex, 0,
+			     sock_net_uid(net, NULL));
+	else
+		ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
+	xfrm_state_put(x);
+
+	return 0;
+}
+
+static int ah6_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
+{
+	struct ah_data *ahp = NULL;
+	struct xfrm_algo_desc *aalg_desc;
+	struct crypto_ahash *ahash;
+
+	if (!x->aalg) {
+		NL_SET_ERR_MSG(extack, "AH requires a state with an AUTH algorithm");
+		goto error;
+	}
+
+	if (x->encap) {
+		NL_SET_ERR_MSG(extack, "AH is not compatible with encapsulation");
+		goto error;
+	}
+
+	ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
+	if (!ahp)
+		return -ENOMEM;
+
+	ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
+	if (IS_ERR(ahash)) {
+		NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations");
+		goto error;
+	}
+
+	ahp->ahash = ahash;
+	if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
+			       (x->aalg->alg_key_len + 7) / 8)) {
+		NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations");
+		goto error;
+	}
+
+	/*
+	 * Lookup the algorithm description maintained by xfrm_algo,
+	 * verify crypto transform properties, and store information
+	 * we need for AH processing.  This lookup cannot fail here
+	 * after a successful crypto_alloc_hash().
+	 */
+	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
+	BUG_ON(!aalg_desc);
+
+	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
+	    crypto_ahash_digestsize(ahash)) {
+		NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations");
+		goto error;
+	}
+
+	ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
+	ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
+
+	x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
+					  ahp->icv_trunc_len);
+	switch (x->props.mode) {
+	case XFRM_MODE_BEET:
+	case XFRM_MODE_TRANSPORT:
+		break;
+	case XFRM_MODE_TUNNEL:
+		x->props.header_len += sizeof(struct ipv6hdr);
+		break;
+	default:
+		NL_SET_ERR_MSG(extack, "Invalid mode requested for AH, must be one of TRANSPORT, TUNNEL, BEET");
+		goto error;
+	}
+	x->data = ahp;
+
+	return 0;
+
+error:
+	if (ahp) {
+		crypto_free_ahash(ahp->ahash);
+		kfree(ahp);
+	}
+	return -EINVAL;
+}
+
+static void ah6_destroy(struct xfrm_state *x)
+{
+	struct ah_data *ahp = x->data;
+
+	if (!ahp)
+		return;
+
+	crypto_free_ahash(ahp->ahash);
+	kfree(ahp);
+}
+
+static int ah6_rcv_cb(struct sk_buff *skb, int err)
+{
+	return 0;
+}
+
+static const struct xfrm_type ah6_type = {
+	.owner		= THIS_MODULE,
+	.proto		= IPPROTO_AH,
+	.flags		= XFRM_TYPE_REPLAY_PROT,
+	.init_state	= ah6_init_state,
+	.destructor	= ah6_destroy,
+	.input		= ah6_input,
+	.output		= ah6_output,
+};
+
+static struct xfrm6_protocol ah6_protocol = {
+	.handler	=	xfrm6_rcv,
+	.input_handler	=	xfrm_input,
+	.cb_handler	=	ah6_rcv_cb,
+	.err_handler	=	ah6_err,
+	.priority	=	0,
+};
+
+static int __init ah6_init(void)
+{
+	if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
+		pr_info("%s: can't add xfrm type\n", __func__);
+		return -EAGAIN;
+	}
+
+	if (xfrm6_protocol_register(&ah6_protocol, IPPROTO_AH) < 0) {
+		pr_info("%s: can't add protocol\n", __func__);
+		xfrm_unregister_type(&ah6_type, AF_INET6);
+		return -EAGAIN;
+	}
+
+	return 0;
+}
+
+static void __exit ah6_fini(void)
+{
+	if (xfrm6_protocol_deregister(&ah6_protocol, IPPROTO_AH) < 0)
+		pr_info("%s: can't remove protocol\n", __func__);
+
+	xfrm_unregister_type(&ah6_type, AF_INET6);
+}
+
+module_init(ah6_init);
+module_exit(ah6_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);