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Commit c9af6db4 authored by Pravin B Shelar's avatar Pravin B Shelar Committed by David S. Miller
Browse files

net: Fix possible wrong checksum generation. 



Patch cef401de (net: fix possible wrong checksum
generation) fixed wrong checksum calculation but it broke TSO by
defining new GSO type but not a netdev feature for that type.
net_gso_ok() would not allow hardware checksum/segmentation
offload of such packets without the feature.

Following patch fixes TSO and wrong checksum. This patch uses
same logic that Eric Dumazet used. Patch introduces new flag
SKBTX_SHARED_FRAG if at least one frag can be modified by
the user. but SKBTX_SHARED_FRAG flag is kept in skb shared
info tx_flags rather than gso_type.

tx_flags is better compared to gso_type since we can have skb with
shared frag without gso packet. It does not link SHARED_FRAG to
GSO, So there is no need to define netdev feature for this.

Signed-off-by: default avatarPravin B Shelar <pshelar@nicira.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b8fa4100

drivers/net/macvtap.c

+2 −2
Original line number Diff line number Diff line
@@ -543,7 +543,6 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from, 
		skb->data_len += len;

		skb->len += len;

		skb->truesize += truesize;

		skb_shinfo(skb)->gso_type |= SKB_GSO_SHARED_FRAG;

		atomic_add(truesize, &skb->sk->sk_wmem_alloc);

		while (len) {

			int off = base & ~PAGE_MASK;
@@ -599,7 +598,7 @@ static int macvtap_skb_from_vnet_hdr(struct sk_buff *skb, 


	if (vnet_hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {

		skb_shinfo(skb)->gso_size = vnet_hdr->gso_size;

		skb_shinfo(skb)->gso_type |= gso_type;

		skb_shinfo(skb)->gso_type = gso_type;



		/* Header must be checked, and gso_segs computed. */

		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
@@ -743,6 +742,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, 
	if (zerocopy) {

		skb_shinfo(skb)->destructor_arg = m->msg_control;

		skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;

		skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;

	}

	if (vlan)

		macvlan_start_xmit(skb, vlan->dev);

drivers/net/tun.c

+5 −8
Original line number Diff line number Diff line
@@ -1019,7 +1019,6 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from, 
		skb->data_len += len;

		skb->len += len;

		skb->truesize += truesize;

		skb_shinfo(skb)->gso_type |= SKB_GSO_SHARED_FRAG;

		atomic_add(truesize, &skb->sk->sk_wmem_alloc);

		while (len) {

			int off = base & ~PAGE_MASK;
@@ -1165,18 +1164,16 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 
	}



	if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {

		unsigned short gso_type = 0;



		pr_debug("GSO!\n");

		switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {

		case VIRTIO_NET_HDR_GSO_TCPV4:

			gso_type = SKB_GSO_TCPV4;

			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;

			break;

		case VIRTIO_NET_HDR_GSO_TCPV6:

			gso_type = SKB_GSO_TCPV6;

			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;

			break;

		case VIRTIO_NET_HDR_GSO_UDP:

			gso_type = SKB_GSO_UDP;

			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;

			break;

		default:

			tun->dev->stats.rx_frame_errors++;
@@ -1185,10 +1182,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 
		}



		if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)

			gso_type |= SKB_GSO_TCP_ECN;

			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;



		skb_shinfo(skb)->gso_size = gso.gso_size;

		skb_shinfo(skb)->gso_type |= gso_type;

		if (skb_shinfo(skb)->gso_size == 0) {

			tun->dev->stats.rx_frame_errors++;

			kfree_skb(skb);
@@ -1204,6 +1200,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 
	if (zerocopy) {

		skb_shinfo(skb)->destructor_arg = msg_control;

		skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;

		skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;

	}



	skb_reset_network_header(skb);

drivers/net/virtio_net.c

+5 −8
Original line number Diff line number Diff line
@@ -227,7 +227,7 @@ static void set_skb_frag(struct sk_buff *skb, struct page *page, 
	skb->len += size;

	skb->truesize += PAGE_SIZE;

	skb_shinfo(skb)->nr_frags++;

	skb_shinfo(skb)->gso_type |= SKB_GSO_SHARED_FRAG;

	skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;

	*len -= size;

}
@@ -387,18 +387,16 @@ static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len) 
		 ntohs(skb->protocol), skb->len, skb->pkt_type);



	if (hdr->hdr.gso_type != VIRTIO_NET_HDR_GSO_NONE) {

		unsigned short gso_type = 0;



		pr_debug("GSO!\n");

		switch (hdr->hdr.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {

		case VIRTIO_NET_HDR_GSO_TCPV4:

			gso_type = SKB_GSO_TCPV4;

			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;

			break;

		case VIRTIO_NET_HDR_GSO_UDP:

			gso_type = SKB_GSO_UDP;

			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;

			break;

		case VIRTIO_NET_HDR_GSO_TCPV6:

			gso_type = SKB_GSO_TCPV6;

			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;

			break;

		default:

			net_warn_ratelimited("%s: bad gso type %u.\n",
@@ -407,7 +405,7 @@ static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len) 
		}



		if (hdr->hdr.gso_type & VIRTIO_NET_HDR_GSO_ECN)

			gso_type |= SKB_GSO_TCP_ECN;

			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;



		skb_shinfo(skb)->gso_size = hdr->hdr.gso_size;

		if (skb_shinfo(skb)->gso_size == 0) {
@@ -415,7 +413,6 @@ static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len) 
			goto frame_err;

		}



		skb_shinfo(skb)->gso_type |= gso_type;

		/* Header must be checked, and gso_segs computed. */

		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;

		skb_shinfo(skb)->gso_segs = 0;

include/linux/skbuff.h

+9 −8
Original line number Diff line number Diff line
@@ -230,6 +230,13 @@ enum { 


	/* generate wifi status information (where possible) */

	SKBTX_WIFI_STATUS = 1 << 4,



	/* This indicates at least one fragment might be overwritten

	 * (as in vmsplice(), sendfile() ...)

	 * If we need to compute a TX checksum, we'll need to copy

	 * all frags to avoid possible bad checksum

	 */

	SKBTX_SHARED_FRAG = 1 << 5,

};



/*
@@ -307,13 +314,6 @@ enum { 
	SKB_GSO_TCPV6 = 1 << 4,



	SKB_GSO_FCOE = 1 << 5,



	/* This indicates at least one fragment might be overwritten

	 * (as in vmsplice(), sendfile() ...)

	 * If we need to compute a TX checksum, we'll need to copy

	 * all frags to avoid possible bad checksum

	 */

	SKB_GSO_SHARED_FRAG = 1 << 6,

};



#if BITS_PER_LONG > 32
@@ -2220,7 +2220,8 @@ static inline int skb_linearize(struct sk_buff *skb) 
 */

static inline bool skb_has_shared_frag(const struct sk_buff *skb)

{

	return skb_shinfo(skb)->gso_type & SKB_GSO_SHARED_FRAG;

	return skb_is_nonlinear(skb) &&

	       skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;

}



/**

net/core/skbuff.c

+2 −3
Original line number Diff line number Diff line
@@ -2326,8 +2326,7 @@ void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len) 
{

	int pos = skb_headlen(skb);



	skb_shinfo(skb1)->gso_type = skb_shinfo(skb)->gso_type;



	skb_shinfo(skb)->tx_flags = skb_shinfo(skb1)->tx_flags & SKBTX_SHARED_FRAG;

	if (len < pos)	/* Split line is inside header. */

		skb_split_inside_header(skb, skb1, len, pos);

	else		/* Second chunk has no header, nothing to copy. */
@@ -2833,7 +2832,7 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) 
		skb_copy_from_linear_data_offset(skb, offset,

						 skb_put(nskb, hsize), hsize);



		skb_shinfo(nskb)->gso_type = skb_shinfo(skb)->gso_type;

		skb_shinfo(nskb)->tx_flags = skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;



		while (pos < offset + len && i < nfrags) {

			*frag = skb_shinfo(skb)->frags[i];