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linux/net/ipv6/ah6.c

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// 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 in6_addr final_addr;
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;
}
final_addr = hao->addr;
hao->addr = iph->saddr;
iph->saddr = final_addr;
}
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 ah_data *ahp = NULL;
struct xfrm_algo_desc *aalg_desc;
struct crypto_ahash *ahash;
if (!x->aalg)
goto error;
if (x->encap)
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))
goto error;
ahp->ahash = ahash;
if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
(x->aalg->alg_key_len + 7) / 8))
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)) {
pr_info("AH: %s digestsize %u != %hu\n",
x->aalg->alg_name, crypto_ahash_digestsize(ahash),
aalg_desc->uinfo.auth.icv_fullbits/8);
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:
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 = {
.description = "AH6",
.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,
.hdr_offset = xfrm6_find_1stfragopt,
};
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);
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