--- /dev/null
+#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;
+ int seqhi_len = 0;
+ __be32 *seqhi;
+ int sglists = 0;
+ struct scatterlist *seqhisg;
+
+ 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);
+
+ if (x->props.flags & XFRM_STATE_ESN) {
+ sglists = 1;
+ seqhi_len = sizeof(*seqhi);
+ }
+ err = -ENOMEM;
+ iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + seqhi_len);
+ if (!iph)
+ goto out;
+ seqhi = (__be32 *)((char *)iph + ihl);
+ icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
+ req = ah_tmp_req(ahash, icv);
+ sg = ah_req_sg(ahash, req);
+ seqhisg = sg + nfrags;
+
+ 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 + sglists);
+ skb_to_sgvec_nomark(skb, sg, 0, skb->len);
+
+ 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, 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);
+
+ if (x->props.mode == XFRM_MODE_TUNNEL)
+ skb_reset_transport_header(skb);
+ else
+ 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;
+ int seqhi_len = 0;
+ __be32 *seqhi;
+ int sglists = 0;
+ struct scatterlist *seqhisg;
+
+ 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_unclone(skb, 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);
+
+ if (x->props.flags & XFRM_STATE_ESN) {
+ sglists = 1;
+ seqhi_len = sizeof(*seqhi);
+ }
+
+ work_iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl +
+ ahp->icv_trunc_len + seqhi_len);
+ if (!work_iph)
+ goto out;
+
+ seqhi = (__be32 *)((char *)work_iph + ihl);
+ auth_data = ah_tmp_auth(seqhi, seqhi_len);
+ icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
+ req = ah_tmp_req(ahash, icv);
+ sg = ah_req_sg(ahash, req);
+ seqhisg = sg + nfrags;
+
+ 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 + sglists);
+ skb_to_sgvec_nomark(skb, sg, 0, skb->len);
+
+ 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, 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);
+ if (x->props.mode == XFRM_MODE_TUNNEL)
+ skb_reset_transport_header(skb);
+ else
+ skb_set_transport_header(skb, -ihl);
+
+ err = nexthdr;
+
+out_free:
+ kfree (work_iph);
+out:
+ return err;
+}
+
+static int 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;
+
+ switch (icmp_hdr(skb)->type) {
+ case ICMP_DEST_UNREACH:
+ if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
+ return 0;
+ case ICMP_REDIRECT:
+ break;
+ default:
+ return 0;
+ }
+
+ x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
+ ah->spi, IPPROTO_AH, AF_INET);
+ if (!x)
+ return 0;
+
+ if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
+ ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_AH, 0);
+ else
+ ipv4_redirect(skb, net, 0, 0, IPPROTO_AH, 0);
+ xfrm_state_put(x);
+
+ return 0;
+}
+
+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;
+
+ 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 int ah4_rcv_cb(struct sk_buff *skb, int err)
+{
+ return 0;
+}
+
+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 struct xfrm4_protocol ah4_protocol = {
+ .handler = xfrm4_rcv,
+ .input_handler = xfrm_input,
+ .cb_handler = ah4_rcv_cb,
+ .err_handler = ah4_err,
+ .priority = 0,
+};
+
+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 (xfrm4_protocol_register(&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 (xfrm4_protocol_deregister(&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);
Code Review / kvmfornfv.git / blobdiff