From 923347bb83c67c3a572b04decb5875c3adb0d306 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Mon, 9 Dec 2013 18:25:16 +0800 Subject: [PATCH] tun: unbreak truncated packet signalling Commit 6680ec68eff47d36f67b4351bc9836fd6cba9532 (tuntap: hardware vlan tx support) breaks the truncated packet signal by never return a length greater than iov length in tun_put_user(). This patch fixes this by always return the length of packet plus possible vlan header. Caller can detect the truncated packet by comparing the return value and the size of iov length. Reported-by: Vlad Yasevich Cc: Vlad Yasevich Cc: Zhi Yong Wu Signed-off-by: Jason Wang Signed-off-by: David S. Miller --- drivers/net/tun.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index e26cbea1ce6..dd1bd7aedc3 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1183,7 +1183,11 @@ static ssize_t tun_put_user(struct tun_struct *tun, const struct iovec *iv, int len) { struct tun_pi pi = { 0, skb->protocol }; - ssize_t total = 0; + struct { + __be16 h_vlan_proto; + __be16 h_vlan_TCI; + } veth; + ssize_t total = 0, off = 0; int vlan_offset = 0; if (!(tun->flags & TUN_NO_PI)) { @@ -1248,14 +1252,11 @@ static ssize_t tun_put_user(struct tun_struct *tun, total += tun->vnet_hdr_sz; } + off = total; if (!vlan_tx_tag_present(skb)) { len = min_t(int, skb->len, len); } else { int copy, ret; - struct { - __be16 h_vlan_proto; - __be16 h_vlan_TCI; - } veth; veth.h_vlan_proto = skb->vlan_proto; veth.h_vlan_TCI = htons(vlan_tx_tag_get(skb)); @@ -1264,22 +1265,22 @@ static ssize_t tun_put_user(struct tun_struct *tun, len = min_t(int, skb->len + VLAN_HLEN, len); copy = min_t(int, vlan_offset, len); - ret = skb_copy_datagram_const_iovec(skb, 0, iv, total, copy); + ret = skb_copy_datagram_const_iovec(skb, 0, iv, off, copy); len -= copy; - total += copy; + off += copy; if (ret || !len) goto done; copy = min_t(int, sizeof(veth), len); - ret = memcpy_toiovecend(iv, (void *)&veth, total, copy); + ret = memcpy_toiovecend(iv, (void *)&veth, off, copy); len -= copy; - total += copy; + off += copy; if (ret || !len) goto done; } - skb_copy_datagram_const_iovec(skb, vlan_offset, iv, total, len); - total += len; + skb_copy_datagram_const_iovec(skb, vlan_offset, iv, off, len); + total += skb->len + (vlan_offset ? sizeof(veth) : 0); done: tun->dev->stats.tx_packets++; -- 2.43.2