diff options
Diffstat (limited to 'net/ipv4/ah4.c')
| -rw-r--r-- | net/ipv4/ah4.c | 538 |
1 files changed, 538 insertions, 0 deletions
diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c new file mode 100644 index 00000000..fd508b52 --- /dev/null +++ b/net/ipv4/ah4.c @@ -0,0 +1,538 @@ +#define pr_fmt(fmt) "IPsec: " fmt + +#include <crypto/hash.h> +#include <linux/err.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <net/ip.h> +#include <net/xfrm.h> +#include <net/ah.h> +#include <linux/crypto.h> +#include <linux/pfkeyv2.h> +#include <linux/scatterlist.h> +#include <net/icmp.h> +#include <net/protocol.h> + +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 u8 *ah_tmp_auth(void *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)); +} + +/* Clear mutable options and find final destination to substitute + * into IP header for icv calculation. Options are already checked + * for validity, so paranoia is not required. */ + +static int ip_clear_mutable_options(const struct iphdr *iph, __be32 *daddr) +{ + unsigned char * optptr = (unsigned char*)(iph+1); + int l = iph->ihl*4 - sizeof(struct iphdr); + int optlen; + + while (l > 0) { + switch (*optptr) { + case IPOPT_END: + return 0; + case IPOPT_NOOP: + l--; + optptr++; + continue; + } + optlen = optptr[1]; + if (optlen<2 || optlen>l) + return -EINVAL; + switch (*optptr) { + case IPOPT_SEC: + case 0x85: /* Some "Extended Security" crap. */ + case IPOPT_CIPSO: + case IPOPT_RA: + case 0x80|21: /* RFC1770 */ + break; + case IPOPT_LSRR: + case IPOPT_SSRR: + if (optlen < 6) + return -EINVAL; + memcpy(daddr, optptr+optlen-4, 4); + /* Fall through */ + default: + memset(optptr, 0, optlen); + } + l -= optlen; + optptr += optlen; + } + return 0; +} + +static void ah_output_done(struct crypto_async_request *base, int err) +{ + u8 *icv; + struct iphdr *iph; + struct sk_buff *skb = base->data; + struct xfrm_state *x = skb_dst(skb)->xfrm; + struct ah_data *ahp = x->data; + struct iphdr *top_iph = ip_hdr(skb); + struct ip_auth_hdr *ah = ip_auth_hdr(skb); + int ihl = ip_hdrlen(skb); + + iph = AH_SKB_CB(skb)->tmp; + icv = ah_tmp_icv(ahp->ahash, iph, ihl); + memcpy(ah->auth_data, icv, ahp->icv_trunc_len); + + top_iph->tos = iph->tos; + top_iph->ttl = iph->ttl; + top_iph->frag_off = iph->frag_off; + if (top_iph->ihl != 5) { + top_iph->daddr = iph->daddr; + memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); + } + + kfree(AH_SKB_CB(skb)->tmp); + xfrm_output_resume(skb, err); +} + +static int ah_output(struct xfrm_state *x, struct sk_buff *skb) +{ + int err; + int nfrags; + int ihl; + u8 *icv; + struct sk_buff *trailer; + struct crypto_ahash *ahash; + struct ahash_request *req; + struct scatterlist *sg; + struct iphdr *iph, *top_iph; + struct ip_auth_hdr *ah; + struct ah_data *ahp; + + ahp = x->data; + ahash = ahp->ahash; + + if ((err = skb_cow_data(skb, 0, &trailer)) < 0) + goto out; + nfrags = err; + + skb_push(skb, -skb_network_offset(skb)); + ah = ip_auth_hdr(skb); + ihl = ip_hdrlen(skb); + + err = -ENOMEM; + iph = ah_alloc_tmp(ahash, nfrags, ihl); + if (!iph) + goto out; + + icv = ah_tmp_icv(ahash, iph, ihl); + req = ah_tmp_req(ahash, icv); + sg = ah_req_sg(ahash, req); + + memset(ah->auth_data, 0, ahp->icv_trunc_len); + + top_iph = ip_hdr(skb); + + iph->tos = top_iph->tos; + iph->ttl = top_iph->ttl; + iph->frag_off = top_iph->frag_off; + + if (top_iph->ihl != 5) { + iph->daddr = top_iph->daddr; + memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); + err = ip_clear_mutable_options(top_iph, &top_iph->daddr); + if (err) + goto out_free; + } + + ah->nexthdr = *skb_mac_header(skb); + *skb_mac_header(skb) = IPPROTO_AH; + + top_iph->tos = 0; + top_iph->tot_len = htons(skb->len); + top_iph->frag_off = 0; + top_iph->ttl = 0; + top_iph->check = 0; + + if (x->props.flags & XFRM_STATE_ALIGN4) + ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; + else + 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); + skb_to_sgvec(skb, sg, 0, skb->len); + + ahash_request_set_crypt(req, sg, icv, skb->len); + ahash_request_set_callback(req, 0, ah_output_done, skb); + + AH_SKB_CB(skb)->tmp = iph; + + err = crypto_ahash_digest(req); + if (err) { + if (err == -EINPROGRESS) + goto out; + + if (err == -EBUSY) + err = NET_XMIT_DROP; + goto out_free; + } + + memcpy(ah->auth_data, icv, ahp->icv_trunc_len); + + top_iph->tos = iph->tos; + top_iph->ttl = iph->ttl; + top_iph->frag_off = iph->frag_off; + if (top_iph->ihl != 5) { + top_iph->daddr = iph->daddr; + memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); + } + +out_free: + kfree(iph); +out: + return err; +} + +static void ah_input_done(struct crypto_async_request *base, int err) +{ + u8 *auth_data; + u8 *icv; + struct iphdr *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 ihl = ip_hdrlen(skb); + int ah_hlen = (ah->hdrlen + 2) << 2; + + work_iph = AH_SKB_CB(skb)->tmp; + auth_data = ah_tmp_auth(work_iph, ihl); + icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len); + + err = memcmp(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, ihl); + __skb_pull(skb, ah_hlen + ihl); + skb_set_transport_header(skb, -ihl); +out: + kfree(AH_SKB_CB(skb)->tmp); + xfrm_input_resume(skb, err); +} + +static int ah_input(struct xfrm_state *x, struct sk_buff *skb) +{ + int ah_hlen; + int ihl; + int nexthdr; + int nfrags; + u8 *auth_data; + u8 *icv; + struct sk_buff *trailer; + struct crypto_ahash *ahash; + struct ahash_request *req; + struct scatterlist *sg; + struct iphdr *iph, *work_iph; + struct ip_auth_hdr *ah; + struct ah_data *ahp; + int err = -ENOMEM; + + if (!pskb_may_pull(skb, sizeof(*ah))) + goto out; + + ah = (struct ip_auth_hdr *)skb->data; + ahp = x->data; + ahash = ahp->ahash; + + nexthdr = ah->nexthdr; + ah_hlen = (ah->hdrlen + 2) << 2; + + if (x->props.flags & XFRM_STATE_ALIGN4) { + if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) && + ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len)) + goto out; + } else { + 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; + + /* We are going to _remove_ AH header to keep sockets happy, + * so... Later this can change. */ + if (skb_cloned(skb) && + pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) + goto out; + + skb->ip_summed = CHECKSUM_NONE; + + + if ((err = skb_cow_data(skb, 0, &trailer)) < 0) + goto out; + nfrags = err; + + ah = (struct ip_auth_hdr *)skb->data; + iph = ip_hdr(skb); + ihl = ip_hdrlen(skb); + + work_iph = ah_alloc_tmp(ahash, nfrags, ihl + ahp->icv_trunc_len); + if (!work_iph) + goto out; + + auth_data = ah_tmp_auth(work_iph, ihl); + icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len); + req = ah_tmp_req(ahash, icv); + sg = ah_req_sg(ahash, req); + + memcpy(work_iph, iph, ihl); + memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); + memset(ah->auth_data, 0, ahp->icv_trunc_len); + + iph->ttl = 0; + iph->tos = 0; + iph->frag_off = 0; + iph->check = 0; + if (ihl > sizeof(*iph)) { + __be32 dummy; + err = ip_clear_mutable_options(iph, &dummy); + if (err) + goto out_free; + } + + skb_push(skb, ihl); + + sg_init_table(sg, nfrags); + skb_to_sgvec(skb, sg, 0, skb->len); + + ahash_request_set_crypt(req, sg, icv, skb->len); + ahash_request_set_callback(req, 0, ah_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 = memcmp(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, ihl); + __skb_pull(skb, ah_hlen + ihl); + skb_set_transport_header(skb, -ihl); + + err = nexthdr; + +out_free: + kfree (work_iph); +out: + return err; +} + +static void ah4_err(struct sk_buff *skb, u32 info) +{ + struct net *net = dev_net(skb->dev); + const struct iphdr *iph = (const struct iphdr *)skb->data; + struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2)); + struct xfrm_state *x; + + if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || + icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) + return; + + x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, + ah->spi, IPPROTO_AH, AF_INET); + if (!x) + return; + printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n", + ntohl(ah->spi), ntohl(iph->daddr)); + xfrm_state_put(x); +} + +static int ah_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_ahash(). + */ + 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("%s: %s digestsize %u != %hu\n", + __func__, 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; + + BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); + + if (x->props.flags & XFRM_STATE_ALIGN4) + x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) + + ahp->icv_trunc_len); + else + x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + + ahp->icv_trunc_len); + if (x->props.mode == XFRM_MODE_TUNNEL) + x->props.header_len += sizeof(struct iphdr); + x->data = ahp; + + return 0; + +error: + if (ahp) { + crypto_free_ahash(ahp->ahash); + kfree(ahp); + } + return -EINVAL; +} + +static void ah_destroy(struct xfrm_state *x) +{ + struct ah_data *ahp = x->data; + + if (!ahp) + return; + + crypto_free_ahash(ahp->ahash); + kfree(ahp); +} + + +static const struct xfrm_type ah_type = +{ + .description = "AH4", + .owner = THIS_MODULE, + .proto = IPPROTO_AH, + .flags = XFRM_TYPE_REPLAY_PROT, + .init_state = ah_init_state, + .destructor = ah_destroy, + .input = ah_input, + .output = ah_output +}; + +static const struct net_protocol ah4_protocol = { + .handler = xfrm4_rcv, + .err_handler = ah4_err, + .no_policy = 1, + .netns_ok = 1, +}; + +static int __init ah4_init(void) +{ + if (xfrm_register_type(&ah_type, AF_INET) < 0) { + pr_info("%s: can't add xfrm type\n", __func__); + return -EAGAIN; + } + if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) { + pr_info("%s: can't add protocol\n", __func__); + xfrm_unregister_type(&ah_type, AF_INET); + return -EAGAIN; + } + return 0; +} + +static void __exit ah4_fini(void) +{ + if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0) + pr_info("%s: can't remove protocol\n", __func__); + if (xfrm_unregister_type(&ah_type, AF_INET) < 0) + pr_info("%s: can't remove xfrm type\n", __func__); +} + +module_init(ah4_init); +module_exit(ah4_fini); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH); |