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Merge branch 'tun-net'
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Herbert Xu says:

====================
tun: Fix csum_start and TUN_PKT_STRIP

The first patch fixes a serious problem that breaks checksum offload
in VMs while the second patch fixes a problem that probably affects
no one.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller committed Nov 3, 2014
2 parents 7071cf7 + 2eb783c commit 2b11e67
Showing 1 changed file with 17 additions and 11 deletions.
28 changes: 17 additions & 11 deletions drivers/net/tun.c
Original file line number Diff line number Diff line change
Expand Up @@ -1235,12 +1235,20 @@ static ssize_t tun_put_user(struct tun_struct *tun,
struct tun_pi pi = { 0, skb->protocol };
ssize_t total = 0;
int vlan_offset = 0, copied;
int vlan_hlen = 0;
int vnet_hdr_sz = 0;

if (vlan_tx_tag_present(skb))
vlan_hlen = VLAN_HLEN;

if (tun->flags & TUN_VNET_HDR)
vnet_hdr_sz = tun->vnet_hdr_sz;

if (!(tun->flags & TUN_NO_PI)) {
if ((len -= sizeof(pi)) < 0)
return -EINVAL;

if (len < skb->len) {
if (len < skb->len + vlan_hlen + vnet_hdr_sz) {
/* Packet will be striped */
pi.flags |= TUN_PKT_STRIP;
}
Expand All @@ -1250,9 +1258,9 @@ static ssize_t tun_put_user(struct tun_struct *tun,
total += sizeof(pi);
}

if (tun->flags & TUN_VNET_HDR) {
if (vnet_hdr_sz) {
struct virtio_net_hdr gso = { 0 }; /* no info leak */
if ((len -= tun->vnet_hdr_sz) < 0)
if ((len -= vnet_hdr_sz) < 0)
return -EINVAL;

if (skb_is_gso(skb)) {
Expand Down Expand Up @@ -1284,7 +1292,8 @@ static ssize_t tun_put_user(struct tun_struct *tun,

if (skb->ip_summed == CHECKSUM_PARTIAL) {
gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
gso.csum_start = skb_checksum_start_offset(skb);
gso.csum_start = skb_checksum_start_offset(skb) +
vlan_hlen;
gso.csum_offset = skb->csum_offset;
} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
Expand All @@ -1293,14 +1302,13 @@ static ssize_t tun_put_user(struct tun_struct *tun,
if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total,
sizeof(gso))))
return -EFAULT;
total += tun->vnet_hdr_sz;
total += vnet_hdr_sz;
}

copied = total;
total += skb->len;
if (!vlan_tx_tag_present(skb)) {
len = min_t(int, skb->len, len);
} else {
len = min_t(int, skb->len + vlan_hlen, len);
total += skb->len + vlan_hlen;
if (vlan_hlen) {
int copy, ret;
struct {
__be16 h_vlan_proto;
Expand All @@ -1311,8 +1319,6 @@ static ssize_t tun_put_user(struct tun_struct *tun,
veth.h_vlan_TCI = htons(vlan_tx_tag_get(skb));

vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
len = min_t(int, skb->len + VLAN_HLEN, len);
total += VLAN_HLEN;

copy = min_t(int, vlan_offset, len);
ret = skb_copy_datagram_const_iovec(skb, 0, iv, copied, copy);
Expand Down

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