#include <linux/err.h> #include <linux/module.h> #include <net/ip.h> #include <net/xfrm.h> #include <net/esp.h> #include <linux/scatterlist.h> #include <linux/crypto.h> #include <linux/kernel.h> #include <linux/pfkeyv2.h> #include <linux/random.h> #include <linux/spinlock.h> #include <linux/in6.h> #include <net/icmp.h> #include <net/protocol.h> #include <net/udp.h> static int esp_output(struct xfrm_state *x, struct sk_buff *skb) { int err; struct ip_esp_hdr *esph; struct crypto_blkcipher *tfm; struct blkcipher_desc desc; struct esp_data *esp; struct sk_buff *trailer; u8 *tail; int blksize; int clen; int alen; int nfrags; /* skb is pure payload to encrypt */ err = -ENOMEM; /* Round to block size */ clen = skb->len; esp = x->data; alen = esp->auth.icv_trunc_len; tfm = esp->conf.tfm; desc.tfm = tfm; desc.flags = 0; blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); clen = ALIGN(clen + 2, blksize); if (esp->conf.padlen) clen = ALIGN(clen, esp->conf.padlen); if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) goto error; /* Fill padding... */ tail = skb_tail_pointer(trailer); do { int i; for (i=0; i<clen-skb->len - 2; i++) tail[i] = i + 1; } while (0); tail[clen - skb->len - 2] = (clen - skb->len) - 2; pskb_put(skb, trailer, clen - skb->len); skb_push(skb, -skb_network_offset(skb)); esph = ip_esp_hdr(skb); *(skb_tail_pointer(trailer) - 1) = *skb_mac_header(skb); *skb_mac_header(skb) = IPPROTO_ESP; spin_lock_bh(&x->lock); /* this is non-NULL only with UDP Encapsulation */ if (x->encap) { struct xfrm_encap_tmpl *encap = x->encap; struct udphdr *uh; __be32 *udpdata32; uh = (struct udphdr *)esph; uh->source = encap->encap_sport; uh->dest = encap->encap_dport; uh->len = htons(skb->len + alen - skb_transport_offset(skb)); uh->check = 0; switch (encap->encap_type) { default: case UDP_ENCAP_ESPINUDP: esph = (struct ip_esp_hdr *)(uh + 1); break; case UDP_ENCAP_ESPINUDP_NON_IKE: udpdata32 = (__be32 *)(uh + 1); udpdata32[0] = udpdata32[1] = 0; esph = (struct ip_esp_hdr *)(udpdata32 + 2); break; } *skb_mac_header(skb) = IPPROTO_UDP; } esph->spi = x->id.spi; esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq); if (esp->conf.ivlen) { if (unlikely(!esp->conf.ivinitted)) { get_random_bytes(esp->conf.ivec, esp->conf.ivlen); esp->conf.ivinitted = 1; } crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen); } do { struct scatterlist *sg = &esp->sgbuf[0]; if (unlikely(nfrags > ESP_NUM_FAST_SG)) { sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); if (!sg) goto unlock; } sg_init_table(sg, nfrags); skb_to_sgvec(skb, sg, esph->enc_data + esp->conf.ivlen - skb->data, clen); err = crypto_blkcipher_encrypt(&desc, sg, sg, clen); if (unlikely(sg != &esp->sgbuf[0])) kfree(sg); } while (0); if (unlikely(err)) goto unlock; if (esp->conf.ivlen) { memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen); crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen); } if (esp->auth.icv_full_len) { err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data, sizeof(*esph) + esp->conf.ivlen + clen); memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen); } unlock: spin_unlock_bh(&x->lock); error: return err; } /* * Note: detecting truncated vs. non-truncated authentication data is very * expensive, so we only support truncated data, which is the recommended * and common case. */ static int esp_input(struct xfrm_state *x, struct sk_buff *skb) { struct iphdr *iph; struct ip_esp_hdr *esph; struct esp_data *esp = x->data; struct crypto_blkcipher *tfm = esp->conf.tfm; struct blkcipher_desc desc = { .tfm = tfm }; struct sk_buff *trailer; int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); int alen = esp->auth.icv_trunc_len; int elen = skb->len - sizeof(*esph) - esp->conf.ivlen - alen; int nfrags; int ihl; u8 nexthdr[2]; struct scatterlist *sg; int padlen; int err; if (!pskb_may_pull(skb, sizeof(*esph))) goto out; if (elen <= 0 || (elen & (blksize-1))) goto out; /* If integrity check is required, do this. */ if (esp->auth.icv_full_len) { u8 sum[alen]; err = esp_mac_digest(esp, skb, 0, skb->len - alen); if (err) goto out; if (skb_copy_bits(skb, skb->len - alen, sum, alen)) BUG(); if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) { x->stats.integrity_failed++; goto out; } } if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) goto out; skb->ip_summed = CHECKSUM_NONE; esph = (struct ip_esp_hdr *)skb->data; /* Get ivec. This can be wrong, check against another impls. */ if (esp->conf.ivlen) crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen); sg = &esp->sgbuf[0]; if (unlikely(nfrags > ESP_NUM_FAST_SG)) { sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); if (!sg) goto out; } sg_init_table(sg, nfrags); skb_to_sgvec(skb, sg, sizeof(*esph) + esp->conf.ivlen, elen); err = crypto_blkcipher_decrypt(&desc, sg, sg, elen); if (unlikely(sg != &esp->sgbuf[0])) kfree(sg); if (unlikely(err)) return err; if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) BUG(); padlen = nexthdr[0]; if (padlen+2 >= elen) goto out; /* ... check padding bits here. Silly. :-) */ /* RFC4303: Drop dummy packets without any error */ if (nexthdr[1] == IPPROTO_NONE) goto out; iph = ip_hdr(skb); ihl = iph->ihl * 4; if (x->encap) { struct xfrm_encap_tmpl *encap = x->encap; struct udphdr *uh = (void *)(skb_network_header(skb) + ihl); /* * 1) if the NAT-T peer's IP or port changed then * advertize the change to the keying daemon. * This is an inbound SA, so just compare * SRC ports. */ if (iph->saddr != x->props.saddr.a4 || uh->source != encap->encap_sport) { xfrm_address_t ipaddr; ipaddr.a4 = iph->saddr; km_new_mapping(x, &ipaddr, uh->source); /* XXX: perhaps add an extra * policy check here, to see * if we should allow or * reject a packet from a * different source * address/port. */ } /* * 2) ignore UDP/TCP checksums in case * of NAT-T in Transport Mode, or * perform other post-processing fixes * as per draft-ietf-ipsec-udp-encaps-06, * section 3.1.2 */ if (x->props.mode == XFRM_MODE_TRANSPORT) skb->ip_summed = CHECKSUM_UNNECESSARY; } pskb_trim(skb, skb->len - alen - padlen - 2); __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen); skb_set_transport_header(skb, -ihl); return nexthdr[1]; out: return -EINVAL; } static u32 esp4_get_mtu(struct xfrm_state *x, int mtu) { struct esp_data *esp = x->data; u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); u32 align = max_t(u32, blksize, esp->conf.padlen); u32 rem; mtu -= x->props.header_len + esp->auth.icv_trunc_len; rem = mtu & (align - 1); mtu &= ~(align - 1); switch (x->props.mode) { case XFRM_MODE_TUNNEL: break; default: case XFRM_MODE_TRANSPORT: /* The worst case */ mtu -= blksize - 4; mtu += min_t(u32, blksize - 4, rem); break; case XFRM_MODE_BEET: /* The worst case. */ mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem); break; } return mtu - 2; } static void esp4_err(struct sk_buff *skb, u32 info) { struct iphdr *iph = (struct iphdr*)skb->data; struct ip_esp_hdr *esph = (struct ip_esp_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((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); if (!x) return; NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", ntohl(esph->spi), ntohl(iph->daddr)); xfrm_state_put(x); } static void esp_destroy(struct xfrm_state *x) { struct esp_data *esp = x->data; if (!esp) return; crypto_free_blkcipher(esp->conf.tfm); esp->conf.tfm = NULL; kfree(esp->conf.ivec); esp->conf.ivec = NULL; crypto_free_hash(esp->auth.tfm); esp->auth.tfm = NULL; kfree(esp->auth.work_icv); esp->auth.work_icv = NULL; kfree(esp); } static int esp_init_state(struct xfrm_state *x) { struct esp_data *esp = NULL; struct crypto_blkcipher *tfm; u32 align; if (x->ealg == NULL) goto error; esp = kzalloc(sizeof(*esp), GFP_KERNEL); if (esp == NULL) return -ENOMEM; if (x->aalg) { struct xfrm_algo_desc *aalg_desc; struct crypto_hash *hash; hash = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC); if (IS_ERR(hash)) goto error; esp->auth.tfm = hash; if (crypto_hash_setkey(hash, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8)) goto error; aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); BUG_ON(!aalg_desc); if (aalg_desc->uinfo.auth.icv_fullbits/8 != crypto_hash_digestsize(hash)) { NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", x->aalg->alg_name, crypto_hash_digestsize(hash), aalg_desc->uinfo.auth.icv_fullbits/8); goto error; } esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); if (!esp->auth.work_icv) goto error; } tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC); if (IS_ERR(tfm)) goto error; esp->conf.tfm = tfm; esp->conf.ivlen = crypto_blkcipher_ivsize(tfm); esp->conf.padlen = 0; if (esp->conf.ivlen) { esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); if (unlikely(esp->conf.ivec == NULL)) goto error; esp->conf.ivinitted = 0; } if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8)) goto error; x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; if (x->props.mode == XFRM_MODE_TUNNEL) x->props.header_len += sizeof(struct iphdr); else if (x->props.mode == XFRM_MODE_BEET) x->props.header_len += IPV4_BEET_PHMAXLEN; if (x->encap) { struct xfrm_encap_tmpl *encap = x->encap; switch (encap->encap_type) { default: goto error; case UDP_ENCAP_ESPINUDP: x->props.header_len += sizeof(struct udphdr); break; case UDP_ENCAP_ESPINUDP_NON_IKE: x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); break; } } x->data = esp; align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); if (esp->conf.padlen) align = max_t(u32, align, esp->conf.padlen); x->props.trailer_len = align + 1 + esp->auth.icv_trunc_len; return 0; error: x->data = esp; esp_destroy(x); x->data = NULL; return -EINVAL; } static struct xfrm_type esp_type = { .description = "ESP4", .owner = THIS_MODULE, .proto = IPPROTO_ESP, .flags = XFRM_TYPE_REPLAY_PROT, .init_state = esp_init_state, .destructor = esp_destroy, .get_mtu = esp4_get_mtu, .input = esp_input, .output = esp_output }; static struct net_protocol esp4_protocol = { .handler = xfrm4_rcv, .err_handler = esp4_err, .no_policy = 1, }; static int __init esp4_init(void) { if (xfrm_register_type(&esp_type, AF_INET) < 0) { printk(KERN_INFO "ip esp init: can't add xfrm type\n"); return -EAGAIN; } if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { printk(KERN_INFO "ip esp init: can't add protocol\n"); xfrm_unregister_type(&esp_type, AF_INET); return -EAGAIN; } return 0; } static void __exit esp4_fini(void) { if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) printk(KERN_INFO "ip esp close: can't remove protocol\n"); if (xfrm_unregister_type(&esp_type, AF_INET) < 0) printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); } module_init(esp4_init); module_exit(esp4_fini); MODULE_LICENSE("GPL"); MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);