esp6: Add support for IPsec extended sequence numbers

This patch adds IPsec extended sequence numbers support to esp6.
We use the authencesn crypto algorithm to handle esp with separate
encryption/authentication algorithms.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/esp6.c

@@ -54,16 +54,20 @@ 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 IV is placed at the front, followed
- * by the request and finally the SG list.
+ * 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)
+static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags, int seqihlen)
 {
 	unsigned int len;
 
-	len = crypto_aead_ivsize(aead);
+	len = seqihlen;
+
+	len += crypto_aead_ivsize(aead);
+
 	if (len) {
 		len += crypto_aead_alignmask(aead) &
 		       ~(crypto_tfm_ctx_alignment() - 1);
@@ -78,10 +82,16 @@ static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags)
 	return kmalloc(len, GFP_ATOMIC);
 }
 
-static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp)
+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, crypto_aead_alignmask(aead) + 1) : tmp;
+	       PTR_ALIGN((u8 *)tmp + seqhilen,
+			 crypto_aead_alignmask(aead) + 1) : tmp + seqhilen;
 }
 
 static inline struct aead_givcrypt_request *esp_tmp_givreq(
@@ -145,8 +155,12 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
 	int plen;
 	int tfclen;
 	int nfrags;
+	int assoclen;
+	int sglists;
+	int seqhilen;
 	u8 *iv;
 	u8 *tail;
+	__be32 *seqhi;
 	struct esp_data *esp = x->data;
 
 	/* skb is pure payload to encrypt */
@@ -175,14 +189,25 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
 		goto error;
 	nfrags = err;
 
-	tmp = esp_alloc_tmp(aead, nfrags + 1);
+	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)
 		goto error;
 
-	iv = esp_tmp_iv(aead, tmp);
+	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 + 1;
+	sg = asg + sglists;
 
 	/* Fill padding... */
 	tail = skb_tail_pointer(trailer);
@@ -210,11 +235,19 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
 	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, sizeof(*esph));
+	aead_givcrypt_set_assoc(req, asg, assoclen);
 	aead_givcrypt_set_giv(req, esph->enc_data,
 			      XFRM_SKB_CB(skb)->seq.output.low);
 
@@ -292,8 +325,12 @@ static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 	struct sk_buff *trailer;
 	int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead);
 	int nfrags;
+	int assoclen;
+	int sglists;
+	int seqhilen;
 	int ret = 0;
 	void *tmp;
+	__be32 *seqhi;
 	u8 *iv;
 	struct scatterlist *sg;
 	struct scatterlist *asg;
@@ -314,12 +351,24 @@ static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 	}
 
 	ret = -ENOMEM;
-	tmp = esp_alloc_tmp(aead, nfrags + 1);
+
+	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)
 		goto out;
 
 	ESP_SKB_CB(skb)->tmp = tmp;
-	iv = esp_tmp_iv(aead, 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 + 1;
@@ -333,11 +382,19 @@ static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 
 	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, sizeof(*esph));
+	aead_request_set_assoc(req, asg, assoclen);
 
 	ret = crypto_aead_decrypt(req);
 	if (ret == -EINPROGRESS)
@@ -443,10 +500,20 @@ static int esp_init_authenc(struct xfrm_state *x)
 		goto error;
 
 	err = -ENAMETOOLONG;
-	if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)",
+
+	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);