#include <crypto/aead.h> #include <crypto/authenc.h> #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/kernel.h> #include <linux/pfkeyv2.h> #include <linux/rtnetlink.h> #include <linux/slab.h> #include <linux/spinlock.h> #include <linux/in6.h> #include <net/icmp.h> #include <net/protocol.h> #include <net/udp.h> struct esp_skb_cb { struct xfrm_skb_cb xfrm; void *tmp; }; #define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0])) /* * Allocate an AEAD request structure with extra space for SG and IV. * * For alignment considerations the IV is placed at the front, followed * by the request and finally the SG list. * * TODO: Use spare space in skb for this where possible. */ static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags) { unsigned int len; len = crypto_aead_ivsize(aead); if (len) { len += crypto_aead_alignmask(aead) & ~(crypto_tfm_ctx_alignment() - 1); len = ALIGN(len, crypto_tfm_ctx_alignment()); } len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead); len = ALIGN(len, __alignof__(struct scatterlist)); len += sizeof(struct scatterlist) * nfrags; return kmalloc(len, GFP_ATOMIC); } static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp) { return crypto_aead_ivsize(aead) ? PTR_ALIGN((u8 *)tmp, crypto_aead_alignmask(aead) + 1) : tmp; } static inline struct aead_givcrypt_request *esp_tmp_givreq( struct crypto_aead *aead, u8 *iv) { struct aead_givcrypt_request *req; req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), crypto_tfm_ctx_alignment()); aead_givcrypt_set_tfm(req, aead); return req; } static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv) { struct aead_request *req; req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead), crypto_tfm_ctx_alignment()); aead_request_set_tfm(req, aead); return req; } static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead, struct aead_request *req) { return (void *)ALIGN((unsigned long)(req + 1) + crypto_aead_reqsize(aead), __alignof__(struct scatterlist)); } static inline struct scatterlist *esp_givreq_sg( struct crypto_aead *aead, struct aead_givcrypt_request *req) { return (void *)ALIGN((unsigned long)(req + 1) + crypto_aead_reqsize(aead), __alignof__(struct scatterlist)); } static void esp_output_done(struct crypto_async_request *base, int err) { struct sk_buff *skb = base->data; kfree(ESP_SKB_CB(skb)->tmp); xfrm_output_resume(skb, err); } static int esp_output(struct xfrm_state *x, struct sk_buff *skb) { int err; struct ip_esp_hdr *esph; struct crypto_aead *aead; struct aead_givcrypt_request *req; struct scatterlist *sg; struct scatterlist *asg; struct esp_data *esp; struct sk_buff *trailer; void *tmp; u8 *iv; 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; aead = esp->aead; alen = crypto_aead_authsize(aead); blksize = ALIGN(crypto_aead_blocksize(aead), 4); clen = ALIGN(clen + 2, blksize); if (esp->padlen) clen = ALIGN(clen, esp->padlen); if ((err = skb_cow_data(skb, clen - skb->len + alen, &trailer)) < 0) goto error; nfrags = err; tmp = esp_alloc_tmp(aead, nfrags + 1); if (!tmp) goto error; iv = esp_tmp_iv(aead, tmp); req = esp_tmp_givreq(aead, iv); asg = esp_givreq_sg(aead, req); sg = asg + 1; /* 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; tail[clen - skb->len - 1] = *skb_mac_header(skb); pskb_put(skb, trailer, clen - skb->len + alen); skb_push(skb, -skb_network_offset(skb)); esph = ip_esp_hdr(skb); *skb_mac_header(skb) = IPPROTO_ESP; /* this is non-NULL only with UDP Encapsulation */ if (x->encap) { struct xfrm_encap_tmpl *encap = x->encap; struct udphdr *uh; __be32 *udpdata32; __be16 sport, dport; int encap_type; spin_lock_bh(&x->lock); sport = encap->encap_sport; dport = encap->encap_dport; encap_type = encap->encap_type; spin_unlock_bh(&x->lock); uh = (struct udphdr *)esph; uh->source = sport; uh->dest = dport; uh->len = htons(skb->len - skb_transport_offset(skb)); uh->check = 0; switch (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.output); sg_init_table(sg, nfrags); skb_to_sgvec(skb, sg, esph->enc_data + crypto_aead_ivsize(aead) - skb->data, clen + alen); sg_init_one(asg, esph, sizeof(*esph)); aead_givcrypt_set_callback(req, 0, esp_output_done, skb); aead_givcrypt_set_crypt(req, sg, sg, clen, iv); aead_givcrypt_set_assoc(req, asg, sizeof(*esph)); aead_givcrypt_set_giv(req, esph->enc_data, XFRM_SKB_CB(skb)->seq.output); ESP_SKB_CB(skb)->tmp = tmp; err = crypto_aead_givencrypt(req); if (err == -EINPROGRESS) goto error; if (err == -EBUSY) err = NET_XMIT_DROP; kfree(tmp); error: return err; } static int esp_input_done2(struct sk_buff *skb, int err) { struct iphdr *iph; struct xfrm_state *x = xfrm_input_state(skb); struct esp_data *esp = x->data; struct crypto_aead *aead = esp->aead; int alen = crypto_aead_authsize(aead); int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead); int elen = skb->len - hlen; int ihl; u8 nexthdr[2]; int padlen; kfree(ESP_SKB_CB(skb)->tmp); if (unlikely(err)) goto out; if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) BUG(); err = -EINVAL; padlen = nexthdr[0]; if (padlen + 2 + alen >= elen) goto out; /* ... check padding bits here. Silly. :-) */ 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, hlen); skb_set_transport_header(skb, -ihl); err = nexthdr[1]; /* RFC4303: Drop dummy packets without any error */ if (err == IPPROTO_NONE) err = -EINVAL; out: return err; } static void esp_input_done(struct crypto_async_request *base, int err) { struct sk_buff *skb = base->data; xfrm_input_resume(skb, esp_input_done2(skb, 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 ip_esp_hdr *esph; struct esp_data *esp = x->data; struct crypto_aead *aead = esp->aead; struct aead_request *req; struct sk_buff *trailer; int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead); int nfrags; void *tmp; u8 *iv; struct scatterlist *sg; struct scatterlist *asg; int err = -EINVAL; if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) goto out; if (elen <= 0) goto out; if ((err = skb_cow_data(skb, 0, &trailer)) < 0) goto out; nfrags = err; err = -ENOMEM; tmp = esp_alloc_tmp(aead, nfrags + 1); if (!tmp) goto out; ESP_SKB_CB(skb)->tmp = tmp; iv = esp_tmp_iv(aead, tmp); req = esp_tmp_req(aead, iv); asg = esp_req_sg(aead, req); sg = asg + 1; skb->ip_summed = CHECKSUM_NONE; esph = (struct ip_esp_hdr *)skb->data; /* Get ivec. This can be wrong, check against another impls. */ iv = esph->enc_data; sg_init_table(sg, nfrags); skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen); sg_init_one(asg, esph, sizeof(*esph)); aead_request_set_callback(req, 0, esp_input_done, skb); aead_request_set_crypt(req, sg, sg, elen, iv); aead_request_set_assoc(req, asg, sizeof(*esph)); err = crypto_aead_decrypt(req); if (err == -EINPROGRESS) goto out; err = esp_input_done2(skb, err); out: return err; } static u32 esp4_get_mtu(struct xfrm_state *x, int mtu) { struct esp_data *esp = x->data; u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4); u32 align = max_t(u32, blksize, esp->padlen); u32 rem; mtu -= x->props.header_len + crypto_aead_authsize(esp->aead); 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_aead(esp->aead); kfree(esp); } static int esp_init_aead(struct xfrm_state *x) { struct esp_data *esp = x->data; struct crypto_aead *aead; int err; aead = crypto_alloc_aead(x->aead->alg_name, 0, 0); err = PTR_ERR(aead); if (IS_ERR(aead)) goto error; esp->aead = aead; err = crypto_aead_setkey(aead, x->aead->alg_key, (x->aead->alg_key_len + 7) / 8); if (err) goto error; err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8); if (err) goto error; error: return err; } static int esp_init_authenc(struct xfrm_state *x) { struct esp_data *esp = x->data; struct crypto_aead *aead; struct crypto_authenc_key_param *param; struct rtattr *rta; char *key; char *p; char authenc_name[CRYPTO_MAX_ALG_NAME]; unsigned int keylen; int err; err = -EINVAL; if (x->ealg == NULL) goto error; err = -ENAMETOOLONG; if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)", x->aalg ? x->aalg->alg_name : "digest_null", x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) goto error; aead = crypto_alloc_aead(authenc_name, 0, 0); err = PTR_ERR(aead); if (IS_ERR(aead)) goto error; esp->aead = aead; keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) + (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param)); err = -ENOMEM; key = kmalloc(keylen, GFP_KERNEL); if (!key) goto error; p = key; rta = (void *)p; rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM; rta->rta_len = RTA_LENGTH(sizeof(*param)); param = RTA_DATA(rta); p += RTA_SPACE(sizeof(*param)); if (x->aalg) { struct xfrm_algo_desc *aalg_desc; memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8); p += (x->aalg->alg_key_len + 7) / 8; aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); BUG_ON(!aalg_desc); err = -EINVAL; if (aalg_desc->uinfo.auth.icv_fullbits/8 != crypto_aead_authsize(aead)) { NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", x->aalg->alg_name, crypto_aead_authsize(aead), aalg_desc->uinfo.auth.icv_fullbits/8); goto free_key; } err = crypto_aead_setauthsize( aead, aalg_desc->uinfo.auth.icv_truncbits / 8); if (err) goto free_key; } param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8); memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8); err = crypto_aead_setkey(aead, key, keylen); free_key: kfree(key); error: return err; } static int esp_init_state(struct xfrm_state *x) { struct esp_data *esp; struct crypto_aead *aead; u32 align; int err; esp = kzalloc(sizeof(*esp), GFP_KERNEL); if (esp == NULL) return -ENOMEM; x->data = esp; if (x->aead) err = esp_init_aead(x); else err = esp_init_authenc(x); if (err) goto error; aead = esp->aead; esp->padlen = 0; x->props.header_len = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead); 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; } } align = ALIGN(crypto_aead_blocksize(aead), 4); if (esp->padlen) align = max_t(u32, align, esp->padlen); x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead); error: return err; } static const 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);