[IPSEC]: Use HMAC template and hash interface

This patch converts IPsec to use the new HMAC template.  The names of
existing simple digest algorithms may still be used to refer to their
HMAC composites.

The same structure can be used by other MACs such as AES-XCBC-MAC.

This patch also switches from the digest interface to hash.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ah.h

@@ -15,22 +15,29 @@ struct ah_data
 	int			icv_full_len;
 	int			icv_trunc_len;
 
-	void			(*icv)(struct ah_data*,
-	                               struct sk_buff *skb, u8 *icv);
-
-	struct crypto_tfm	*tfm;
+	struct crypto_hash	*tfm;
 };
 
-static inline void
-ah_hmac_digest(struct ah_data *ahp, struct sk_buff *skb, u8 *auth_data)
+static inline int ah_mac_digest(struct ah_data *ahp, struct sk_buff *skb,
+				u8 *auth_data)
 {
-	struct crypto_tfm *tfm = ahp->tfm;
+	struct hash_desc desc;
+	int err;
+
+	desc.tfm = ahp->tfm;
+	desc.flags = 0;
 
 	memset(auth_data, 0, ahp->icv_trunc_len);
-	crypto_hmac_init(tfm, ahp->key, &ahp->key_len);
-	skb_icv_walk(skb, tfm, 0, skb->len, crypto_hmac_update);
-	crypto_hmac_final(tfm, ahp->key, &ahp->key_len, ahp->work_icv);
-	memcpy(auth_data, ahp->work_icv, ahp->icv_trunc_len);
+	err = crypto_hash_init(&desc);
+	if (unlikely(err))
+		goto out;
+	err = skb_icv_walk(skb, &desc, 0, skb->len, crypto_hash_update);
+	if (unlikely(err))
+		goto out;
+	err = crypto_hash_final(&desc, ahp->work_icv);
+
+out:
+	return err;
 }
 
 #endif

include/net/esp.h

@@ -35,7 +35,7 @@ struct esp_data
 		void			(*icv)(struct esp_data*,
 		                               struct sk_buff *skb,
 		                               int offset, int len, u8 *icv);
-		struct crypto_tfm	*tfm;
+		struct crypto_hash	*tfm;
 	} auth;
 };
 
@@ -43,18 +43,22 @@ extern int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset,
 extern int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
 extern void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
 
-static inline void
-esp_hmac_digest(struct esp_data *esp, struct sk_buff *skb, int offset,
-                int len, u8 *auth_data)
+static inline int esp_mac_digest(struct esp_data *esp, struct sk_buff *skb,
+				 int offset, int len)
 {
-	struct crypto_tfm *tfm = esp->auth.tfm;
-	char *icv = esp->auth.work_icv;
-
-	memset(auth_data, 0, esp->auth.icv_trunc_len);
-	crypto_hmac_init(tfm, esp->auth.key, &esp->auth.key_len);
-	skb_icv_walk(skb, tfm, offset, len, crypto_hmac_update);
-	crypto_hmac_final(tfm, esp->auth.key, &esp->auth.key_len, icv);
-	memcpy(auth_data, icv, esp->auth.icv_trunc_len);
+	struct hash_desc desc;
+	int err;
+
+	desc.tfm = esp->auth.tfm;
+	desc.flags = 0;
+
+	err = crypto_hash_init(&desc);
+	if (unlikely(err))
+		return err;
+	err = skb_icv_walk(skb, &desc, offset, len, crypto_hash_update);
+	if (unlikely(err))
+		return err;
+	return crypto_hash_final(&desc, esp->auth.work_icv);
 }
 
 #endif

include/net/xfrm.h

@@ -984,11 +984,12 @@ extern struct xfrm_algo_desc *xfrm_aalg_get_byname(char *name, int probe);
 extern struct xfrm_algo_desc *xfrm_ealg_get_byname(char *name, int probe);
 extern struct xfrm_algo_desc *xfrm_calg_get_byname(char *name, int probe);
 
-struct crypto_tfm;
+struct hash_desc;
 struct scatterlist;
-typedef void (icv_update_fn_t)(struct crypto_tfm *, struct scatterlist *, unsigned int);
+typedef int (icv_update_fn_t)(struct hash_desc *, struct scatterlist *,
+			      unsigned int);
 
-extern void skb_icv_walk(const struct sk_buff *skb, struct crypto_tfm *tfm,
+extern int skb_icv_walk(const struct sk_buff *skb, struct hash_desc *tfm,
 			int offset, int len, icv_update_fn_t icv_update);
 
 static inline int xfrm_addr_cmp(xfrm_address_t *a, xfrm_address_t *b,

net/ipv4/ah4.c

+#include <linux/err.h>
 #include <linux/module.h>
 #include <net/ip.h>
 #include <net/xfrm.h>
@@ -97,7 +98,10 @@ static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
 	ah->spi = x->id.spi;
 	ah->seq_no = htonl(++x->replay.oseq);
 	xfrm_aevent_doreplay(x);
-	ahp->icv(ahp, skb, ah->auth_data);
+	err = ah_mac_digest(ahp, skb, ah->auth_data);
+	if (err)
+		goto error;
+	memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len);
 
 	top_iph->tos = iph->tos;
 	top_iph->ttl = iph->ttl;
@@ -119,6 +123,7 @@ static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
 {
 	int ah_hlen;
 	int ihl;
+	int err = -EINVAL;
 	struct iphdr *iph;
 	struct ip_auth_hdr *ah;
 	struct ah_data *ahp;
@@ -166,8 +171,11 @@ static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
 		
 		memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
 		skb_push(skb, ihl);
-		ahp->icv(ahp, skb, ah->auth_data);
-		if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
+		err = ah_mac_digest(ahp, skb, ah->auth_data);
+		if (err)
+			goto out;
+		err = -EINVAL;
+		if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len)) {
 			x->stats.integrity_failed++;
 			goto out;
 		}
@@ -179,7 +187,7 @@ static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
 	return 0;
 
 out:
-	return -EINVAL;
+	return err;
 }
 
 static void ah4_err(struct sk_buff *skb, u32 info)
@@ -204,6 +212,7 @@ static int ah_init_state(struct xfrm_state *x)
 {
 	struct ah_data *ahp = NULL;
 	struct xfrm_algo_desc *aalg_desc;
+	struct crypto_hash *tfm;
 
 	if (!x->aalg)
 		goto error;
@@ -221,24 +230,27 @@ static int ah_init_state(struct xfrm_state *x)
 
 	ahp->key = x->aalg->alg_key;
 	ahp->key_len = (x->aalg->alg_key_len+7)/8;
-	ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
-	if (!ahp->tfm)
+	tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(tfm))
+		goto error;
+
+	ahp->tfm = tfm;
+	if (crypto_hash_setkey(tfm, ahp->key, ahp->key_len))
 		goto error;
-	ahp->icv = ah_hmac_digest;
 	
 	/*
 	 * Lookup the algorithm description maintained by xfrm_algo,
 	 * verify crypto transform properties, and store information
 	 * we need for AH processing.  This lookup cannot fail here
-	 * after a successful crypto_alloc_tfm().
+	 * after a successful crypto_alloc_hash().
 	 */
 	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(ahp->tfm)) {
+	    crypto_hash_digestsize(tfm)) {
 		printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
-		       x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
+		       x->aalg->alg_name, crypto_hash_digestsize(tfm),
 		       aalg_desc->uinfo.auth.icv_fullbits/8);
 		goto error;
 	}
@@ -262,7 +274,7 @@ static int ah_init_state(struct xfrm_state *x)
 error:
 	if (ahp) {
 		kfree(ahp->work_icv);
-		crypto_free_tfm(ahp->tfm);
+		crypto_free_hash(ahp->tfm);
 		kfree(ahp);
 	}
 	return -EINVAL;
@@ -277,7 +289,7 @@ static void ah_destroy(struct xfrm_state *x)
 
 	kfree(ahp->work_icv);
 	ahp->work_icv = NULL;
-	crypto_free_tfm(ahp->tfm);
+	crypto_free_hash(ahp->tfm);
 	ahp->tfm = NULL;
 	kfree(ahp);
 }

net/ipv4/esp4.c

@@ -121,9 +121,9 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
 	}
 
 	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);
+		err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
+				     sizeof(*esph) + esp->conf.ivlen + clen);
+		memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
 	}
 
 	ip_send_check(top_iph);
@@ -163,15 +163,16 @@ static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
 
 	/* If integrity check is required, do this. */
 	if (esp->auth.icv_full_len) {
-		u8 sum[esp->auth.icv_full_len];
-		u8 sum1[alen];
+		u8 sum[alen];
 
-		esp->auth.icv(esp, skb, 0, skb->len-alen, sum);
+		err = esp_mac_digest(esp, skb, 0, skb->len - alen);
+		if (err)
+			goto out;
 
-		if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
+		if (skb_copy_bits(skb, skb->len - alen, sum, alen))
 			BUG();
 
-		if (unlikely(memcmp(sum, sum1, alen))) {
+		if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
 			x->stats.integrity_failed++;
 			goto out;
 		}
@@ -307,7 +308,7 @@ static void esp_destroy(struct xfrm_state *x)
 	esp->conf.tfm = NULL;
 	kfree(esp->conf.ivec);
 	esp->conf.ivec = NULL;
-	crypto_free_tfm(esp->auth.tfm);
+	crypto_free_hash(esp->auth.tfm);
 	esp->auth.tfm = NULL;
 	kfree(esp->auth.work_icv);
 	esp->auth.work_icv = NULL;
@@ -333,22 +334,27 @@ static int esp_init_state(struct xfrm_state *x)
 
 	if (x->aalg) {
 		struct xfrm_algo_desc *aalg_desc;
+		struct crypto_hash *hash;
 
 		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)
+		hash = crypto_alloc_hash(x->aalg->alg_name, 0,
+					 CRYPTO_ALG_ASYNC);
+		if (IS_ERR(hash))
+			goto error;
+
+		esp->auth.tfm = hash;
+		if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
 			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)) {
+		    crypto_hash_digestsize(hash)) {
 			NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 				 x->aalg->alg_name,
-				 crypto_tfm_alg_digestsize(esp->auth.tfm),
+				 crypto_hash_digestsize(hash),
 				 aalg_desc->uinfo.auth.icv_fullbits/8);
 			goto error;
 		}

net/ipv6/ah6.c

@@ -213,7 +213,10 @@ static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
 	ah->spi = x->id.spi;
 	ah->seq_no = htonl(++x->replay.oseq);
 	xfrm_aevent_doreplay(x);
-	ahp->icv(ahp, skb, ah->auth_data);
+	err = ah_mac_digest(ahp, skb, ah->auth_data);
+	if (err)
+		goto error_free_iph;
+	memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len);
 
 	err = 0;
 
@@ -251,6 +254,7 @@ static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 	u16 hdr_len;
 	u16 ah_hlen;
 	int nexthdr;
+	int err = -EINVAL;
 
 	if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
 		goto out;
@@ -292,8 +296,11 @@ static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 		memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
 		memset(ah->auth_data, 0, ahp->icv_trunc_len);
 		skb_push(skb, hdr_len);
-		ahp->icv(ahp, skb, ah->auth_data);
-		if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
+		err = ah_mac_digest(ahp, skb, ah->auth_data);
+		if (err)
+			goto free_out;
+		err = -EINVAL;
+		if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len)) {
 			LIMIT_NETDEBUG(KERN_WARNING "ipsec ah authentication error\n");
 			x->stats.integrity_failed++;
 			goto free_out;
@@ -310,7 +317,7 @@ static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 free_out:
 	kfree(tmp_hdr);
 out:
-	return -EINVAL;
+	return err;
 }
 
 static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 
@@ -338,6 +345,7 @@ static int ah6_init_state(struct xfrm_state *x)
 {
 	struct ah_data *ahp = NULL;
 	struct xfrm_algo_desc *aalg_desc;
+	struct crypto_hash *tfm;
 
 	if (!x->aalg)
 		goto error;
@@ -355,24 +363,27 @@ static int ah6_init_state(struct xfrm_state *x)
 
 	ahp->key = x->aalg->alg_key;
 	ahp->key_len = (x->aalg->alg_key_len+7)/8;
-	ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
-	if (!ahp->tfm)
+	tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(tfm))
+		goto error;
+
+	ahp->tfm = tfm;
+	if (crypto_hash_setkey(tfm, ahp->key, ahp->key_len))
 		goto error;
-	ahp->icv = ah_hmac_digest;
 	
 	/*
 	 * Lookup the algorithm description maintained by xfrm_algo,
 	 * verify crypto transform properties, and store information
 	 * we need for AH processing.  This lookup cannot fail here
-	 * after a successful crypto_alloc_tfm().
+	 * after a successful crypto_alloc_hash().
 	 */
 	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(ahp->tfm)) {
+	    crypto_hash_digestsize(tfm)) {
 		printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
-		       x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
+		       x->aalg->alg_name, crypto_hash_digestsize(tfm),
 		       aalg_desc->uinfo.auth.icv_fullbits/8);
 		goto error;
 	}
@@ -396,7 +407,7 @@ static int ah6_init_state(struct xfrm_state *x)
 error:
 	if (ahp) {
 		kfree(ahp->work_icv);
-		crypto_free_tfm(ahp->tfm);
+		crypto_free_hash(ahp->tfm);
 		kfree(ahp);
 	}
 	return -EINVAL;
@@ -411,7 +422,7 @@ static void ah6_destroy(struct xfrm_state *x)
 
 	kfree(ahp->work_icv);
 	ahp->work_icv = NULL;
-	crypto_free_tfm(ahp->tfm);
+	crypto_free_hash(ahp->tfm);
 	ahp->tfm = NULL;
 	kfree(ahp);
 }

net/ipv6/esp6.c

@@ -125,9 +125,9 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
 	}
 
 	if (esp->auth.icv_full_len) {
-		esp->auth.icv(esp, skb, (u8*)esph-skb->data,
-			sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen+clen, trailer->tail);
-		pskb_put(skb, trailer, alen);
+		err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
+				     sizeof(*esph) + esp->conf.ivlen + clen);
+		memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
 	}
 
 error:
@@ -162,15 +162,16 @@ static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 
 	/* If integrity check is required, do this. */
         if (esp->auth.icv_full_len) {
-		u8 sum[esp->auth.icv_full_len];
-		u8 sum1[alen];
+		u8 sum[alen];
 
-		esp->auth.icv(esp, skb, 0, skb->len-alen, sum);
+		ret = esp_mac_digest(esp, skb, 0, skb->len - alen);
+		if (ret)
+			goto out;
 
-		if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
+		if (skb_copy_bits(skb, skb->len - alen, sum, alen))
 			BUG();
 
-		if (unlikely(memcmp(sum, sum1, alen))) {
+		if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
 			x->stats.integrity_failed++;
 			ret = -EINVAL;
 			goto out;
@@ -279,7 +280,7 @@ static void esp6_destroy(struct xfrm_state *x)
 	esp->conf.tfm = NULL;
 	kfree(esp->conf.ivec);
 	esp->conf.ivec = NULL;
-	crypto_free_tfm(esp->auth.tfm);
+	crypto_free_hash(esp->auth.tfm);
 	esp->auth.tfm = NULL;
 	kfree(esp->auth.work_icv);
 	esp->auth.work_icv = NULL;
@@ -308,22 +309,27 @@ static int esp6_init_state(struct xfrm_state *x)
 
 	if (x->aalg) {
 		struct xfrm_algo_desc *aalg_desc;
+		struct crypto_hash *hash;
 
 		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)
+		hash = crypto_alloc_hash(x->aalg->alg_name, 0,
+					 CRYPTO_ALG_ASYNC);
+		if (IS_ERR(hash))
+			goto error;
+
+		esp->auth.tfm = hash;
+		if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
 			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)) {
-				printk(KERN_INFO "ESP: %s digestsize %u != %hu\n",
+		    crypto_hash_digestsize(hash)) {
+			NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
 				 x->aalg->alg_name,
-					crypto_tfm_alg_digestsize(esp->auth.tfm),
+				 crypto_hash_digestsize(hash),
 				 aalg_desc->uinfo.auth.icv_fullbits/8);
 			goto error;
 		}

net/xfrm/xfrm_algo.c

@@ -30,7 +30,8 @@
  */
 static struct xfrm_algo_desc aalg_list[] = {
 {
-	.name = "digest_null",
+	.name = "hmac(digest_null)",
+	.compat = "digest_null",
 	
 	.uinfo = {
 		.auth = {
@@ -47,7 +48,8 @@ static struct xfrm_algo_desc aalg_list[] = {
 	}
 },
 {
-	.name = "md5",
+	.name = "hmac(md5)",
+	.compat = "md5",
 
 	.uinfo = {
 		.auth = {
@@ -64,7 +66,8 @@ static struct xfrm_algo_desc aalg_list[] = {
 	}
 },
 {
-	.name = "sha1",
+	.name = "hmac(sha1)",
+	.compat = "sha1",
 
 	.uinfo = {
 		.auth = {
@@ -81,7 +84,8 @@ static struct xfrm_algo_desc aalg_list[] = {
 	}
 },
 {
-	.name = "sha256",
+	.name = "hmac(sha256)",
+	.compat = "sha256",
 
 	.uinfo = {
 		.auth = {
@@ -98,7 +102,8 @@ static struct xfrm_algo_desc aalg_list[] = {
 	}
 },
 {
-	.name = "ripemd160",
+	.name = "hmac(ripemd160)",
+	.compat = "ripemd160",
 
 	.uinfo = {
 		.auth = {
@@ -480,11 +485,12 @@ EXPORT_SYMBOL_GPL(xfrm_count_enc_supported);
 
 /* Move to common area: it is shared with AH. */
 
-void skb_icv_walk(const struct sk_buff *skb, struct crypto_tfm *tfm,
+int skb_icv_walk(const struct sk_buff *skb, struct hash_desc *desc,
 		 int offset, int len, icv_update_fn_t icv_update)
 {
 	int start = skb_headlen(skb);
 	int i, copy = start - offset;
+	int err;
 	struct scatterlist sg;
 
 	/* Checksum header. */
@@ -496,10 +502,12 @@ void skb_icv_walk(const struct sk_buff *skb, struct crypto_tfm *tfm,
 		sg.offset = (unsigned long)(skb->data + offset) % PAGE_SIZE;
 		sg.length = copy;
 		
-		icv_update(tfm, &sg, 1);
+		err = icv_update(desc, &sg, copy);
+		if (unlikely(err))
+			return err;
 		
 		if ((len -= copy) == 0)
-			return;
+			return 0;
 		offset += copy;
 	}
 
@@ -519,10 +527,12 @@ void skb_icv_walk(const struct sk_buff *skb, struct crypto_tfm *tfm,
 			sg.offset = frag->page_offset + offset-start;
 			sg.length = copy;
 			
-			icv_update(tfm, &sg, 1);
+			err = icv_update(desc, &sg, copy);
+			if (unlikely(err))
+				return err;
 
 			if (!(len -= copy))
-				return;
+				return 0;
 			offset += copy;
 		}
 		start = end;
@@ -540,15 +550,19 @@ void skb_icv_walk(const struct sk_buff *skb, struct crypto_tfm *tfm,
 			if ((copy = end - offset) > 0) {
 				if (copy > len)
 					copy = len;
-				skb_icv_walk(list, tfm, offset-start, copy, icv_update);
+				err = skb_icv_walk(list, desc, offset-start,
+						   copy, icv_update);
+				if (unlikely(err))
+					return err;
 				if ((len -= copy) == 0)
-					return;
+					return 0;
 				offset += copy;
 			}
 			start = end;
 		}
 	}
 	BUG_ON(len);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(skb_icv_walk);