#include <linux/config.h> #include <linux/module.h> #include <net/ip.h> #include <net/xfrm.h> #include <net/esp.h> #include <asm/scatterlist.h> #include <linux/crypto.h> #include <linux/pfkeyv2.h> #include <linux/random.h> #include <net/icmp.h> #include <net/udp.h> /* decapsulation data for use when post-processing */ struct esp_decap_data { xfrm_address_t saddr; __u16 sport; __u8 proto; }; static int esp_output(struct xfrm_state *x, struct sk_buff *skb) { int err; struct iphdr *top_iph; struct ip_esp_hdr *esph; struct crypto_tfm *tfm; struct esp_data *esp; struct sk_buff *trailer; int blksize; int clen; int alen; int nfrags; /* Strip IP+ESP header. */ __skb_pull(skb, skb->h.raw - skb->data); /* Now 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; blksize = (crypto_tfm_alg_blocksize(tfm) + 3) & ~3; clen = (clen + 2 + blksize-1)&~(blksize-1); if (esp->conf.padlen) clen = (clen + esp->conf.padlen-1)&~(esp->conf.padlen-1); if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) goto error; /* Fill padding... */ do { int i; for (i=0; i<clen-skb->len - 2; i++) *(u8*)(trailer->tail + i) = i+1; } while (0); *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2; pskb_put(skb, trailer, clen - skb->len); __skb_push(skb, skb->data - skb->nh.raw); top_iph = skb->nh.iph; esph = (struct ip_esp_hdr *)(skb->nh.raw + top_iph->ihl*4); top_iph->tot_len = htons(skb->len + alen); *(u8*)(trailer->tail - 1) = top_iph->protocol; /* this is non-NULL only with UDP Encapsulation */ if (x->encap) { struct xfrm_encap_tmpl *encap = x->encap; struct udphdr *uh; u32 *udpdata32; uh = (struct udphdr *)esph; uh->source = encap->encap_sport; uh->dest = encap->encap_dport; uh->len = htons(skb->len + alen - top_iph->ihl*4); 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 = (u32 *)(uh + 1); udpdata32[0] = udpdata32[1] = 0; esph = (struct ip_esp_hdr *)(udpdata32 + 2); break; } top_iph->protocol = IPPROTO_UDP; } else top_iph->protocol = IPPROTO_ESP; esph->spi = x->id.spi; esph->seq_no = htonl(++x->replay.oseq); if (esp->conf.ivlen) crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 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 error; } skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); crypto_cipher_encrypt(tfm, sg, sg, clen); if (unlikely(sg != &esp->sgbuf[0])) kfree(sg); } while (0); if (esp->conf.ivlen) { memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); } if (esp->auth.icv_full_len) { esp->auth.icv(esp, skb, (u8*)esph-skb->data, sizeof(struct ip_esp_hdr) + esp->conf.ivlen+clen, trailer->tail); pskb_put(skb, trailer, alen); } ip_send_check(top_iph); err = 0; 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 xfrm_decap_state *decap, struct sk_buff *skb) { struct iphdr *iph; struct ip_esp_hdr *esph; struct esp_data *esp = x->data; struct sk_buff *trailer; int blksize = crypto_tfm_alg_blocksize(esp->conf.tfm); int alen = esp->auth.icv_trunc_len; int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen; int nfrags; int encap_len = 0; if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr))) 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[esp->auth.icv_full_len]; u8 sum1[alen]; esp->auth.icv(esp, skb, 0, skb->len-alen, sum); if (skb_copy_bits(skb, skb->len-alen, sum1, alen)) BUG(); if (unlikely(memcmp(sum, sum1, 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; iph = skb->nh.iph; /* Get ivec. This can be wrong, check against another impls. */ if (esp->conf.ivlen) crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); { u8 nexthdr[2]; struct scatterlist *sg = &esp->sgbuf[0]; u8 workbuf[60]; int padlen; if (unlikely(nfrags > ESP_NUM_FAST_SG)) { sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); if (!sg) goto out; } skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen); crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); if (unlikely(sg != &esp->sgbuf[0])) kfree(sg); 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. :-) */ if (x->encap && decap && decap->decap_type) { struct esp_decap_data *encap_data; struct udphdr *uh = (struct udphdr *) (iph+1); encap_data = (struct esp_decap_data *) (decap->decap_data); encap_data->proto = 0; switch (decap->decap_type) { case UDP_ENCAP_ESPINUDP: case UDP_ENCAP_ESPINUDP_NON_IKE: encap_data->proto = AF_INET; encap_data->saddr.a4 = iph->saddr; encap_data->sport = uh->source; encap_len = (void*)esph - (void*)uh; break; default: goto out; } } iph->protocol = nexthdr[1]; pskb_trim(skb, skb->len - alen - padlen - 2); memcpy(workbuf, skb->nh.raw, iph->ihl*4); skb->h.raw = skb_pull(skb, sizeof(struct ip_esp_hdr) + esp->conf.ivlen); skb->nh.raw += encap_len + sizeof(struct ip_esp_hdr) + esp->conf.ivlen; memcpy(skb->nh.raw, workbuf, iph->ihl*4); skb->nh.iph->tot_len = htons(skb->len); } return 0; out: return -EINVAL; } static int esp_post_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) { if (x->encap) { struct xfrm_encap_tmpl *encap; struct esp_decap_data *decap_data; encap = x->encap; decap_data = (struct esp_decap_data *)(decap->decap_data); /* first, make sure that the decap type == the encap type */ if (encap->encap_type != decap->decap_type) return -EINVAL; switch (encap->encap_type) { default: case UDP_ENCAP_ESPINUDP: case UDP_ENCAP_ESPINUDP_NON_IKE: /* * 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 (decap_data->proto == AF_INET && (decap_data->saddr.a4 != x->props.saddr.a4 || decap_data->sport != encap->encap_sport)) { xfrm_address_t ipaddr; ipaddr.a4 = decap_data->saddr.a4; km_new_mapping(x, &ipaddr, decap_data->sport); /* 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) skb->ip_summed = CHECKSUM_UNNECESSARY; break; } } return 0; } static u32 esp4_get_max_size(struct xfrm_state *x, int mtu) { struct esp_data *esp = x->data; u32 blksize = crypto_tfm_alg_blocksize(esp->conf.tfm); if (x->props.mode) { mtu = (mtu + 2 + blksize-1)&~(blksize-1); } else { /* The worst case. */ mtu += 2 + blksize; } if (esp->conf.padlen) mtu = (mtu + esp->conf.padlen-1)&~(esp->conf.padlen-1); return mtu + x->props.header_len + esp->auth.icv_trunc_len; } 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 (skb->h.icmph->type != ICMP_DEST_UNREACH || skb->h.icmph->code != ICMP_FRAG_NEEDED) return; x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); if (!x) return; NETDEBUG(printk(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; if (esp->conf.tfm) { crypto_free_tfm(esp->conf.tfm); esp->conf.tfm = NULL; } if (esp->conf.ivec) { kfree(esp->conf.ivec); esp->conf.ivec = NULL; } if (esp->auth.tfm) { crypto_free_tfm(esp->auth.tfm); esp->auth.tfm = NULL; } if (esp->auth.work_icv) { kfree(esp->auth.work_icv); esp->auth.work_icv = NULL; } kfree(esp); } static int esp_init_state(struct xfrm_state *x, void *args) { struct esp_data *esp = NULL; /* null auth and encryption can have zero length keys */ if (x->aalg) { if (x->aalg->alg_key_len > 512) goto error; } if (x->ealg == NULL) goto error; esp = kmalloc(sizeof(*esp), GFP_KERNEL); if (esp == NULL) return -ENOMEM; memset(esp, 0, sizeof(*esp)); if (x->aalg) { struct xfrm_algo_desc *aalg_desc; esp->auth.key = x->aalg->alg_key; esp->auth.key_len = (x->aalg->alg_key_len+7)/8; esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); if (esp->auth.tfm == NULL) goto error; esp->auth.icv = esp_hmac_digest; aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); BUG_ON(!aalg_desc); if (aalg_desc->uinfo.auth.icv_fullbits/8 != crypto_tfm_alg_digestsize(esp->auth.tfm)) { NETDEBUG(printk(KERN_INFO "ESP: %s digestsize %u != %hu\n", x->aalg->alg_name, crypto_tfm_alg_digestsize(esp->auth.tfm), 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; } esp->conf.key = x->ealg->alg_key; esp->conf.key_len = (x->ealg->alg_key_len+7)/8; if (x->props.ealgo == SADB_EALG_NULL) esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); else esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); if (esp->conf.tfm == NULL) goto error; esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.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; get_random_bytes(esp->conf.ivec, esp->conf.ivlen); } if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) goto error; x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; if (x->props.mode) x->props.header_len += sizeof(struct iphdr); 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; x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_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, .init_state = esp_init_state, .destructor = esp_destroy, .get_max_size = esp4_get_max_size, .input = esp_input, .post_input = esp_post_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) { struct xfrm_decap_state decap; if (sizeof(struct esp_decap_data) < sizeof(decap.decap_data)) { extern void decap_data_too_small(void); decap_data_too_small(); } 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");