Account for the IP version of the tunnel when accounting skb headroom on xmit. This avoids having to potentially copy the skb a second time down the stack due to allocating not enough space for IPv6 headers in case the tunnel uses IPv6. Fixes: b784e7ebfce8 ("L2TP:Adjust intf MTU, add underlay L3, L2 hdrs.") Signed-off-by: David Bauer --- net/l2tp/l2tp_core.c | 3 ++- net/l2tp/l2tp_core.h | 1 + net/l2tp/l2tp_eth.c | 9 ++------- 3 files changed, 5 insertions(+), 8 deletions(-) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 687c1366a4d0f..b07b4861f2f59 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1234,7 +1234,7 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, uns * make room. Adjust truesize. */ uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(*uh) : 0; - headroom = NET_SKB_PAD + sizeof(struct iphdr) + uhlen + session->hdr_len; + headroom = NET_SKB_PAD + tunnel->l3_overhead + uhlen + session->hdr_len; if (skb_cow_head(skb, headroom)) { kfree_skb(skb); return NET_XMIT_DROP; @@ -1680,6 +1680,7 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, } sk->sk_allocation = GFP_ATOMIC; + tunnel->l3_overhead = kernel_sock_ip_overhead(sk); release_sock(sk); sock_hold(sk); diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h index ffd8ced3a51ff..aab574376d95f 100644 --- a/net/l2tp/l2tp_core.h +++ b/net/l2tp/l2tp_core.h @@ -167,6 +167,7 @@ struct l2tp_tunnel { u32 tunnel_id; u32 peer_tunnel_id; int version; /* 2=>L2TPv2, 3=>L2TPv3 */ + int l3_overhead; /* IP header overhead */ char name[L2TP_TUNNEL_NAME_MAX]; /* for logging */ enum l2tp_encap_type encap; diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c index cf0b66f4fb29b..709e1fb1b2e3c 100644 --- a/net/l2tp/l2tp_eth.c +++ b/net/l2tp/l2tp_eth.c @@ -187,7 +187,6 @@ static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, struct net_device *dev) { unsigned int overhead = 0; - u32 l3_overhead = 0; u32 mtu; /* if the encap is UDP, account for UDP header size */ @@ -196,11 +195,7 @@ static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, dev->needed_headroom += sizeof(struct udphdr); } - lock_sock(tunnel->sock); - l3_overhead = kernel_sock_ip_overhead(tunnel->sock); - release_sock(tunnel->sock); - - if (l3_overhead == 0) { + if (tunnel->l3_overhead == 0) { /* L3 Overhead couldn't be identified, this could be * because tunnel->sock was NULL or the socket's * address family was not IPv4 or IPv6, @@ -211,7 +206,7 @@ static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr * UDP overhead, if any, was already factored in above. */ - overhead += session->hdr_len + ETH_HLEN + l3_overhead; + overhead += session->hdr_len + ETH_HLEN + tunnel->l3_overhead; mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead; if (mtu < dev->min_mtu || mtu > dev->max_mtu) -- 2.51.0