diff options
Diffstat (limited to 'net/ipv4/esp4.c')
-rw-r--r-- | net/ipv4/esp4.c | 731 |
1 files changed, 731 insertions, 0 deletions
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c new file mode 100644 index 000000000..30b544f02 --- /dev/null +++ b/net/ipv4/esp4.c @@ -0,0 +1,731 @@ +#define pr_fmt(fmt) "IPsec: " fmt + +#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])) + +static u32 esp4_get_mtu(struct xfrm_state *x, int mtu); + +/* + * 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, int seqhilen) +{ + unsigned int len; + + len = seqhilen; + + 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 __be32 *esp_tmp_seqhi(void *tmp) +{ + return PTR_ALIGN((__be32 *)tmp, __alignof__(__be32)); +} +static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int seqhilen) +{ + return crypto_aead_ivsize(aead) ? + PTR_ALIGN((u8 *)tmp + seqhilen, + crypto_aead_alignmask(aead) + 1) : tmp + seqhilen; +} + +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 sk_buff *trailer; + void *tmp; + u8 *iv; + u8 *tail; + int blksize; + int clen; + int alen; + int plen; + int tfclen; + int nfrags; + int assoclen; + int sglists; + int seqhilen; + __be32 *seqhi; + + /* skb is pure payload to encrypt */ + + aead = x->data; + alen = crypto_aead_authsize(aead); + + tfclen = 0; + if (x->tfcpad) { + struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb); + u32 padto; + + padto = min(x->tfcpad, esp4_get_mtu(x, dst->child_mtu_cached)); + if (skb->len < padto) + tfclen = padto - skb->len; + } + blksize = ALIGN(crypto_aead_blocksize(aead), 4); + clen = ALIGN(skb->len + 2 + tfclen, blksize); + plen = clen - skb->len - tfclen; + + err = skb_cow_data(skb, tfclen + plen + alen, &trailer); + if (err < 0) + goto error; + nfrags = err; + + assoclen = sizeof(*esph); + sglists = 1; + seqhilen = 0; + + if (x->props.flags & XFRM_STATE_ESN) { + sglists += 2; + seqhilen += sizeof(__be32); + assoclen += seqhilen; + } + + tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen); + if (!tmp) { + err = -ENOMEM; + goto error; + } + + seqhi = esp_tmp_seqhi(tmp); + iv = esp_tmp_iv(aead, tmp, seqhilen); + req = esp_tmp_givreq(aead, iv); + asg = esp_givreq_sg(aead, req); + sg = asg + sglists; + + /* Fill padding... */ + tail = skb_tail_pointer(trailer); + if (tfclen) { + memset(tail, 0, tfclen); + tail += tfclen; + } + do { + int i; + for (i = 0; i < plen - 2; i++) + tail[i] = i + 1; + } while (0); + tail[plen - 2] = plen - 2; + tail[plen - 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.low); + + sg_init_table(sg, nfrags); + skb_to_sgvec(skb, sg, + esph->enc_data + crypto_aead_ivsize(aead) - skb->data, + clen + alen); + + if ((x->props.flags & XFRM_STATE_ESN)) { + sg_init_table(asg, 3); + sg_set_buf(asg, &esph->spi, sizeof(__be32)); + *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); + sg_set_buf(asg + 1, seqhi, seqhilen); + sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32)); + } else + 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, assoclen); + aead_givcrypt_set_giv(req, esph->enc_data, + XFRM_SKB_CB(skb)->seq.output.low + + ((u64)XFRM_SKB_CB(skb)->seq.output.hi << 32)); + + 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) +{ + const struct iphdr *iph; + struct xfrm_state *x = xfrm_input_state(skb); + struct crypto_aead *aead = x->data; + 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); + if (x->props.mode == XFRM_MODE_TUNNEL) + skb_reset_transport_header(skb); + else + 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 crypto_aead *aead = x->data; + struct aead_request *req; + struct sk_buff *trailer; + int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead); + int nfrags; + int assoclen; + int sglists; + int seqhilen; + __be32 *seqhi; + 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; + + err = skb_cow_data(skb, 0, &trailer); + if (err < 0) + goto out; + + nfrags = err; + + assoclen = sizeof(*esph); + sglists = 1; + seqhilen = 0; + + if (x->props.flags & XFRM_STATE_ESN) { + sglists += 2; + seqhilen += sizeof(__be32); + assoclen += seqhilen; + } + + err = -ENOMEM; + tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen); + if (!tmp) + goto out; + + ESP_SKB_CB(skb)->tmp = tmp; + seqhi = esp_tmp_seqhi(tmp); + iv = esp_tmp_iv(aead, tmp, seqhilen); + req = esp_tmp_req(aead, iv); + asg = esp_req_sg(aead, req); + sg = asg + sglists; + + 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); + + if ((x->props.flags & XFRM_STATE_ESN)) { + sg_init_table(asg, 3); + sg_set_buf(asg, &esph->spi, sizeof(__be32)); + *seqhi = XFRM_SKB_CB(skb)->seq.input.hi; + sg_set_buf(asg + 1, seqhi, seqhilen); + sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32)); + } else + 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, assoclen); + + 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 crypto_aead *aead = x->data; + u32 blksize = ALIGN(crypto_aead_blocksize(aead), 4); + unsigned int net_adj; + + switch (x->props.mode) { + case XFRM_MODE_TRANSPORT: + case XFRM_MODE_BEET: + net_adj = sizeof(struct iphdr); + break; + case XFRM_MODE_TUNNEL: + net_adj = 0; + break; + default: + BUG(); + } + + return ((mtu - x->props.header_len - crypto_aead_authsize(aead) - + net_adj) & ~(blksize - 1)) + net_adj - 2; +} + +static int esp4_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_esp_hdr *esph = (struct ip_esp_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, + esph->spi, IPPROTO_ESP, AF_INET); + if (!x) + return 0; + + if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) + ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ESP, 0); + else + ipv4_redirect(skb, net, 0, 0, IPPROTO_ESP, 0); + xfrm_state_put(x); + + return 0; +} + +static void esp_destroy(struct xfrm_state *x) +{ + struct crypto_aead *aead = x->data; + + if (!aead) + return; + + crypto_free_aead(aead); +} + +static int esp_init_aead(struct xfrm_state *x) +{ + 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; + + x->data = 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 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) + goto error; + + err = -ENAMETOOLONG; + + if ((x->props.flags & XFRM_STATE_ESN)) { + if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, + "authencesn(%s,%s)", + x->aalg ? x->aalg->alg_name : "digest_null", + x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME) + goto error; + } else { + 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; + + x->data = 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)) { + pr_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, x->aalg->alg_trunc_len / 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 crypto_aead *aead; + u32 align; + int err; + + x->data = NULL; + + if (x->aead) + err = esp_init_aead(x); + else + err = esp_init_authenc(x); + + if (err) + goto error; + + aead = x->data; + + 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->sel.family != AF_INET6) + 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); + x->props.trailer_len = align + 1 + crypto_aead_authsize(aead); + +error: + return err; +} + +static int esp4_rcv_cb(struct sk_buff *skb, int err) +{ + return 0; +} + +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 xfrm4_protocol esp4_protocol = { + .handler = xfrm4_rcv, + .input_handler = xfrm_input, + .cb_handler = esp4_rcv_cb, + .err_handler = esp4_err, + .priority = 0, +}; + +static int __init esp4_init(void) +{ + if (xfrm_register_type(&esp_type, AF_INET) < 0) { + pr_info("%s: can't add xfrm type\n", __func__); + return -EAGAIN; + } + if (xfrm4_protocol_register(&esp4_protocol, IPPROTO_ESP) < 0) { + pr_info("%s: can't add protocol\n", __func__); + xfrm_unregister_type(&esp_type, AF_INET); + return -EAGAIN; + } + return 0; +} + +static void __exit esp4_fini(void) +{ + if (xfrm4_protocol_deregister(&esp4_protocol, IPPROTO_ESP) < 0) + pr_info("%s: can't remove protocol\n", __func__); + if (xfrm_unregister_type(&esp_type, AF_INET) < 0) + pr_info("%s: can't remove xfrm type\n", __func__); +} + +module_init(esp4_init); +module_exit(esp4_fini); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP); |