net: add skb frag size accessors

To ease skb->truesize sanitization, its better to be able to localize
all references to skb frags size.

Define accessors : skb_frag_size() to fetch frag size, and
skb_frag_size_{set|add|sub}() to manipulate it.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 18 insertions, 17 deletions

diff --git a/net/ipv4/inet_lro.c b/net/ipv4/inet_lro.c
index 8e6be5aad11..cc280a3f4f9 100644
--- a/net/ipv4/inet_lro.c
+++ b/net/ipv4/inet_lro.c
@@ -244,11 +244,11 @@ static void lro_add_frags(struct net_lro_desc *lro_desc,
 	skb->truesize += truesize;
 
 	skb_frags[0].page_offset += hlen;
-	skb_frags[0].size -= hlen;
+	skb_frag_size_sub(&skb_frags[0], hlen);
 
 	while (tcp_data_len > 0) {
 		*(lro_desc->next_frag) = *skb_frags;
-		tcp_data_len -= skb_frags->size;
+		tcp_data_len -= skb_frag_size(skb_frags);
 		lro_desc->next_frag++;
 		skb_frags++;
 		skb_shinfo(skb)->nr_frags++;
@@ -400,14 +400,14 @@ static struct sk_buff *lro_gen_skb(struct net_lro_mgr *lro_mgr,
 	skb_frags = skb_shinfo(skb)->frags;
 	while (data_len > 0) {
 		*skb_frags = *frags;
-		data_len -= frags->size;
+		data_len -= skb_frag_size(frags);
 		skb_frags++;
 		frags++;
 		skb_shinfo(skb)->nr_frags++;
 	}
 
 	skb_shinfo(skb)->frags[0].page_offset += hdr_len;
-	skb_shinfo(skb)->frags[0].size -= hdr_len;
+	skb_frag_size_sub(&skb_shinfo(skb)->frags[0], hdr_len);
 
 	skb->ip_summed = ip_summed;
 	skb->csum = sum;
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 763589ad673..fdaabf2f2b6 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -599,8 +599,8 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 		head->next = clone;
 		skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 		skb_frag_list_init(head);
-		for (i=0; i<skb_shinfo(head)->nr_frags; i++)
-			plen += skb_shinfo(head)->frags[i].size;
+		for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
+			plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
 		clone->len = clone->data_len = head->data_len - plen;
 		head->data_len -= clone->len;
 		head->len -= clone->len;
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index ae3bb147aff..e1374ab034b 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1015,13 +1015,13 @@ alloc_new_skb:
 				err = -EMSGSIZE;
 				goto error;
 			}
-			if (getfrag(from, skb_frag_address(frag)+frag->size,
+			if (getfrag(from, skb_frag_address(frag)+skb_frag_size(frag),
 				    offset, copy, skb->len, skb) < 0) {
 				err = -EFAULT;
 				goto error;
 			}
 			cork->off += copy;
-			frag->size += copy;
+			skb_frag_size_add(frag, copy);
 			skb->len += copy;
 			skb->data_len += copy;
 			skb->truesize += copy;
@@ -1230,7 +1230,7 @@ ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
 		if (len > size)
 			len = size;
 		if (skb_can_coalesce(skb, i, page, offset)) {
-			skb_shinfo(skb)->frags[i-1].size += len;
+			skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len);
 		} else if (i < MAX_SKB_FRAGS) {
 			get_page(page);
 			skb_fill_page_desc(skb, i, page, offset, len);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4c0da24fb64..132be081cd0 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -813,7 +813,7 @@ new_segment:
 			goto wait_for_memory;
 
 		if (can_coalesce) {
-			skb_shinfo(skb)->frags[i - 1].size += copy;
+			skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
 		} else {
 			get_page(page);
 			skb_fill_page_desc(skb, i, page, offset, copy);
@@ -1058,8 +1058,7 @@ new_segment:
 
 				/* Update the skb. */
 				if (merge) {
-					skb_shinfo(skb)->frags[i - 1].size +=
-									copy;
+					skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
 				} else {
 					skb_fill_page_desc(skb, i, page, off, copy);
 					if (TCP_PAGE(sk)) {
@@ -3031,8 +3030,8 @@ int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
 	for (i = 0; i < shi->nr_frags; ++i) {
 		const struct skb_frag_struct *f = &shi->frags[i];
 		struct page *page = skb_frag_page(f);
-		sg_set_page(&sg, page, f->size, f->page_offset);
-		if (crypto_hash_update(desc, &sg, f->size))
+		sg_set_page(&sg, page, skb_frag_size(f), f->page_offset);
+		if (crypto_hash_update(desc, &sg, skb_frag_size(f)))
 			return 1;
 	}
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index dde6b576831..ed96c543f1c 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1094,14 +1094,16 @@ static void __pskb_trim_head(struct sk_buff *skb, int len)
 	eat = len;
 	k = 0;
 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
-		if (skb_shinfo(skb)->frags[i].size <= eat) {
+		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
+
+		if (size <= eat) {
 			skb_frag_unref(skb, i);
-			eat -= skb_shinfo(skb)->frags[i].size;
+			eat -= size;
 		} else {
 			skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
 			if (eat) {
 				skb_shinfo(skb)->frags[k].page_offset += eat;
-				skb_shinfo(skb)->frags[k].size -= eat;
+				skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat);
 				eat = 0;
 			}
 			k++;