text: /*
   * Copyright (C)2002 USAGI/WIDE Project
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, see <http://www.gnu.org/licenses/>.
   *
   * Authors
   *
   *	Mitsuru KANDA @USAGI       : IPv6 Support
   *	Kazunori MIYAZAWA @USAGI   :
   *	Kunihiro Ishiguro <kunihiro@ipinfusion.com>
   *
   *	This file is derived from net/ipv4/esp.c
   */
  
  #define pr_fmt(fmt) "IPv6: " 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/random.h>
  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <net/ip6_route.h>
  #include <net/icmp.h>
  #include <net/ipv6.h>
  #include <net/protocol.h>
  #include <linux/icmpv6.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 esp6_get_mtu(struct xfrm_state *x, int mtu);
  
  /*
   * Allocate an AEAD request structure with extra space for SG and IV.
   *
   * For alignment considerations the upper 32 bits of the sequence number are
   * placed at the front, if present. Followed by the IV, 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 seqihlen)
  {
  	unsigned int len;
  
  	len = seqihlen;
  
  	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_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_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 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);
  }
  
  /* Move ESP header back into place. */
  static void esp_restore_header(struct sk_buff *skb, unsigned int offset)
  {
  	struct ip_esp_hdr *esph = (void *)(skb->data + offset);
  	void *tmp = ESP_SKB_CB(skb)->tmp;
  	__be32 *seqhi = esp_tmp_seqhi(tmp);
  
  	esph->seq_no = esph->spi;
  	esph->spi = *seqhi;
  }
  
  static void esp_output_restore_header(struct sk_buff *skb)
  {
  	esp_restore_header(skb, skb_transport_offset(skb) - sizeof(__be32));
  }
  
  static void esp_output_done_esn(struct crypto_async_request *base, int err)
  {
  	struct sk_buff *skb = base->data;
  
  	esp_output_restore_header(skb);
  	esp_output_done(base, err);
  }
  
  static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
  {
  	int err;
  	struct ip_esp_hdr *esph;
  	struct crypto_aead *aead;
  	struct aead_request *req;
  	struct scatterlist *sg;
  	struct sk_buff *trailer;
  	void *tmp;
  	int blksize;
  	int clen;
  	int alen;
  	int plen;
  	int ivlen;
  	int tfclen;
  	int nfrags;
  	int assoclen;
  	int seqhilen;
  	u8 *iv;
  	u8 *tail;
  	__be32 *seqhi;
  	__be64 seqno;
  
  	/* skb is pure payload to encrypt */
  	aead = x->data;
  	alen = crypto_aead_authsize(aead);
  	ivlen = crypto_aead_ivsize(aead);
  
  	tfclen = 0;
  	if (x->tfcpad) {
  		struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
  		u32 padto;
  
  		padto = min(x->tfcpad, esp6_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);
  	seqhilen = 0;
  
  	if (x->props.flags & XFRM_STATE_ESN) {
  		seqhilen += sizeof(__be32);
  		assoclen += seqhilen;
  	}
  
  	tmp = esp_alloc_tmp(aead, nfrags, seqhilen);
  	if (!tmp) {
  		err = -ENOMEM;
  		goto error;
  	}
  
  	seqhi = esp_tmp_seqhi(tmp);
  	iv = esp_tmp_iv(aead, tmp, seqhilen);
  	req = esp_tmp_req(aead, iv);
  	sg = esp_req_sg(aead, req);
  
  	/* 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;
  
  	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
  
  	aead_request_set_callback(req, 0, esp_output_done, skb);
  
  	/* For ESN we move the header forward by 4 bytes to
  	 * accomodate the high bits.  We will move it back after
  	 * encryption.
  	 */
  	if ((x->props.flags & XFRM_STATE_ESN)) {
  		esph = (void *)(skb_transport_header(skb) - sizeof(__be32));
  		*seqhi = esph->spi;
  		esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
  		aead_request_set_callback(req, 0, esp_output_done_esn, skb);
  	}
  
  	esph->spi = x->id.spi;
  
  	sg_init_table(sg, nfrags);
  	err = skb_to_sgvec(skb, sg,
  		           (unsigned char *)esph - skb->data,
  		           assoclen + ivlen + clen + alen);
  	if (unlikely(err < 0))
  		goto error;
  
  	aead_request_set_crypt(req, sg, sg, ivlen + clen, iv);
  	aead_request_set_ad(req, assoclen);
  
  	seqno = cpu_to_be64(XFRM_SKB_CB(skb)->seq.output.low +
  			    ((u64)XFRM_SKB_CB(skb)->seq.output.hi << 32));
  
  	memset(iv, 0, ivlen);
  	memcpy(iv + ivlen - min(ivlen, 8), (u8 *)&seqno + 8 - min(ivlen, 8),
  	       min(ivlen, 8));
  
  	ESP_SKB_CB(skb)->tmp = tmp;
  	err = crypto_aead_encrypt(req);
  
  	switch (err) {
  	case -EINPROGRESS:
  		goto error;
  
  	case -EBUSY:
  		err = NET_XMIT_DROP;
  		break;
  
  	case 0:
  		if ((x->props.flags & XFRM_STATE_ESN))
  			esp_output_restore_header(skb);
  	}
  
  	kfree(tmp);
  
  error:
  	return err;
  }
  
  static int esp_input_done2(struct sk_buff *skb, int err)
  {
  	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 hdr_len = skb_network_header_len(skb);
  	int padlen;
  	u8 nexthdr[2];
  
  	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) {
  		net_dbg_ratelimited("ipsec esp packet is garbage padlen=%d, elen=%d\n",
  				    padlen + 2, elen - alen);
  		goto out;
  	}
  
  	/* ... check padding bits here. Silly. :-) */
  
  	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, -hdr_len);
  
  	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));
  }
  
  static void esp_input_restore_header(struct sk_buff *skb)
  {
  	esp_restore_header(skb, 0);
  	__skb_pull(skb, 4);
  }
  
  static void esp_input_done_esn(struct crypto_async_request *base, int err)
  {
  	struct sk_buff *skb = base->data;
  
  	esp_input_restore_header(skb);
  	esp_input_done(base, err);
  }
  
  static int esp6_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 ivlen = crypto_aead_ivsize(aead);
  	int elen = skb->len - sizeof(*esph) - ivlen;
  	int nfrags;
  	int assoclen;
  	int seqhilen;
  	int ret = 0;
  	void *tmp;
  	__be32 *seqhi;
  	u8 *iv;
  	struct scatterlist *sg;
  
  	if (!pskb_may_pull(skb, sizeof(*esph) + ivlen)) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	if (elen <= 0) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	nfrags = skb_cow_data(skb, 0, &trailer);
  	if (nfrags < 0) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	ret = -ENOMEM;
  
  	assoclen = sizeof(*esph);
  	seqhilen = 0;
  
  	if (x->props.flags & XFRM_STATE_ESN) {
  		seqhilen += sizeof(__be32);
  		assoclen += seqhilen;
  	}
  
  	tmp = esp_alloc_tmp(aead, nfrags, 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);
  	sg = esp_req_sg(aead, req);
  
  	skb->ip_summed = CHECKSUM_NONE;
  
  	esph = (struct ip_esp_hdr *)skb->data;
  
  	aead_request_set_callback(req, 0, esp_input_done, skb);
  
  	/* For ESN we move the header forward by 4 bytes to
  	 * accomodate the high bits.  We will move it back after
  	 * decryption.
  	 */
  	if ((x->props.flags & XFRM_STATE_ESN)) {
  		esph = (void *)skb_push(skb, 4);
  		*seqhi = esph->spi;
  		esph->spi = esph->seq_no;
  		esph->seq_no = XFRM_SKB_CB(skb)->seq.input.hi;
  		aead_request_set_callback(req, 0, esp_input_done_esn, skb);
  	}
  
  	sg_init_table(sg, nfrags);
  	ret = skb_to_sgvec(skb, sg, 0, skb->len);
  	if (unlikely(ret < 0))
  		goto out;
  
  	aead_request_set_crypt(req, sg, sg, elen + ivlen, iv);
  	aead_request_set_ad(req, assoclen);
  
  	ret = crypto_aead_decrypt(req);
  	if (ret == -EINPROGRESS)
  		goto out;
  
  	if ((x->props.flags & XFRM_STATE_ESN))
  		esp_input_restore_header(skb);
  
  	ret = esp_input_done2(skb, ret);
  
  out:
  	return ret;
  }
  
  static u32 esp6_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;
  
  	if (x->props.mode != XFRM_MODE_TUNNEL)
  		net_adj = sizeof(struct ipv6hdr);
  	else
  		net_adj = 0;
  
  	return ((mtu - x->props.header_len - crypto_aead_authsize(aead) -
  		 net_adj) & ~(blksize - 1)) + net_adj - 2;
  }
  
  static int esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
  		    u8 type, u8 code, int offset, __be32 info)
  {
  	struct net *net = dev_net(skb->dev);
  	const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
  	struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset);
  	struct xfrm_state *x;
  
  	if (type != ICMPV6_PKT_TOOBIG &&
  	    type != NDISC_REDIRECT)
  		return 0;
  
  	x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
  			      esph->spi, IPPROTO_ESP, AF_INET6);
  	if (!x)
  		return 0;
  
  	if (type == NDISC_REDIRECT)
  		ip6_redirect(skb, net, skb->dev->ifindex, 0,
  			     sock_net_uid(net, NULL));
  	else
  		ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
  	xfrm_state_put(x);
  
  	return 0;
  }
  
  static void esp6_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)
  {
  	char aead_name[CRYPTO_MAX_ALG_NAME];
  	struct crypto_aead *aead;
  	int err;
  
  	err = -ENAMETOOLONG;
  	if (snprintf(aead_name, CRYPTO_MAX_ALG_NAME, "%s(%s)",
  		     x->geniv, x->aead->alg_name) >= CRYPTO_MAX_ALG_NAME)
  		goto error;
  
  	aead = crypto_alloc_aead(aead_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,
  			     "%s%sauthencesn(%s,%s)%s",
  			     x->geniv ?: "", x->geniv ? "(" : "",
  			     x->aalg ? x->aalg->alg_name : "digest_null",
  			     x->ealg->alg_name,
  			     x->geniv ? ")" : "") >= CRYPTO_MAX_ALG_NAME)
  			goto error;
  	} else {
  		if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
  			     "%s%sauthenc(%s,%s)%s",
  			     x->geniv ?: "", x->geniv ? "(" : "",
  			     x->aalg ? x->aalg->alg_name : "digest_null",
  			     x->ealg->alg_name,
  			     x->geniv ? ")" : "") >= 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 esp6_init_state(struct xfrm_state *x)
  {
  	struct crypto_aead *aead;
  	u32 align;
  	int err;
  
  	if (x->encap)
  		return -EINVAL;
  
  	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);
  	switch (x->props.mode) {
  	case XFRM_MODE_BEET:
  		if (x->sel.family != AF_INET6)
  			x->props.header_len += IPV4_BEET_PHMAXLEN +
  					       (sizeof(struct ipv6hdr) - sizeof(struct iphdr));
  		break;
  	case XFRM_MODE_TRANSPORT:
  		break;
  	case XFRM_MODE_TUNNEL:
  		x->props.header_len += sizeof(struct ipv6hdr);
  		break;
  	default:
  		goto error;
  	}
  
  	align = ALIGN(crypto_aead_blocksize(aead), 4);
  	x->props.trailer_len = align + 1 + crypto_aead_authsize(aead);
  
  error:
  	return err;
  }
  
  static int esp6_rcv_cb(struct sk_buff *skb, int err)
  {
  	return 0;
  }
  
  static const struct xfrm_type esp6_type = {
  	.description	= "ESP6",
  	.owner		= THIS_MODULE,
  	.proto		= IPPROTO_ESP,
  	.flags		= XFRM_TYPE_REPLAY_PROT,
  	.init_state	= esp6_init_state,
  	.destructor	= esp6_destroy,
  	.get_mtu	= esp6_get_mtu,
  	.input		= esp6_input,
  	.output		= esp6_output,
  	.hdr_offset	= xfrm6_find_1stfragopt,
  };
  
  static struct xfrm6_protocol esp6_protocol = {
  	.handler	=	xfrm6_rcv,
  	.cb_handler	=	esp6_rcv_cb,
  	.err_handler	=	esp6_err,
  	.priority	=	0,
  };
  
  static int __init esp6_init(void)
  {
  	if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
  		pr_info("%s: can't add xfrm type\n", __func__);
  		return -EAGAIN;
  	}
  	if (xfrm6_protocol_register(&esp6_protocol, IPPROTO_ESP) < 0) {
  		pr_info("%s: can't add protocol\n", __func__);
  		xfrm_unregister_type(&esp6_type, AF_INET6);
  		return -EAGAIN;
  	}
  
  	return 0;
  }
  
  static void __exit esp6_fini(void)
  {
  	if (xfrm6_protocol_deregister(&esp6_protocol, IPPROTO_ESP) < 0)
  		pr_info("%s: can't remove protocol\n", __func__);
  	if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
  		pr_info("%s: can't remove xfrm type\n", __func__);
  }
  
  module_init(esp6_init);
  module_exit(esp6_fini);
  
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP);
  