![Florian Westphal](/assets/img/avatar_default.png)
skb_gso_segment() has a 'features' argument representing offload features available to the output path. A few handlers, e.g. GRE, instead re-fetch the features of skb->dev and use those instead of the provided ones when handing encapsulation/tunnels. Depending on dev->hw_enc_features of the output device skb_gso_segment() can then return NULL even when the caller has disabled all GSO feature bits, as segmentation of inner header thinks device will take care of segmentation. This e.g. affects the tbf scheduler, which will silently drop GRE-encap GSO skbs that did not fit the remaining token quota as the segmentation does not work when device supports corresponding hw offload capabilities. Cc: Pravin B Shelar <pshelar@nicira.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
396 lines
9.7 KiB
C
396 lines
9.7 KiB
C
/*
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* IPV4 GSO/GRO offload support
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* Linux INET implementation
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* UDPv4 GSO support
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*/
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#include <linux/skbuff.h>
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#include <net/udp.h>
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#include <net/protocol.h>
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static DEFINE_SPINLOCK(udp_offload_lock);
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static struct udp_offload_priv __rcu *udp_offload_base __read_mostly;
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#define udp_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&udp_offload_lock))
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struct udp_offload_priv {
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struct udp_offload *offload;
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struct rcu_head rcu;
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struct udp_offload_priv __rcu *next;
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};
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static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
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netdev_features_t features,
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struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
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netdev_features_t features),
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__be16 new_protocol)
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{
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struct sk_buff *segs = ERR_PTR(-EINVAL);
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u16 mac_offset = skb->mac_header;
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int mac_len = skb->mac_len;
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int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
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__be16 protocol = skb->protocol;
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netdev_features_t enc_features;
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int udp_offset, outer_hlen;
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unsigned int oldlen;
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bool need_csum;
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oldlen = (u16)~skb->len;
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if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
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goto out;
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skb->encapsulation = 0;
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__skb_pull(skb, tnl_hlen);
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skb_reset_mac_header(skb);
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skb_set_network_header(skb, skb_inner_network_offset(skb));
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skb->mac_len = skb_inner_network_offset(skb);
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skb->protocol = new_protocol;
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need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
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if (need_csum)
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skb->encap_hdr_csum = 1;
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/* segment inner packet. */
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enc_features = skb->dev->hw_enc_features & features;
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segs = gso_inner_segment(skb, enc_features);
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if (IS_ERR_OR_NULL(segs)) {
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skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
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mac_len);
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goto out;
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}
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outer_hlen = skb_tnl_header_len(skb);
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udp_offset = outer_hlen - tnl_hlen;
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skb = segs;
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do {
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struct udphdr *uh;
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int len;
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skb_reset_inner_headers(skb);
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skb->encapsulation = 1;
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skb->mac_len = mac_len;
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skb_push(skb, outer_hlen);
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skb_reset_mac_header(skb);
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skb_set_network_header(skb, mac_len);
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skb_set_transport_header(skb, udp_offset);
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len = skb->len - udp_offset;
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uh = udp_hdr(skb);
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uh->len = htons(len);
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if (need_csum) {
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__be32 delta = htonl(oldlen + len);
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uh->check = ~csum_fold((__force __wsum)
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((__force u32)uh->check +
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(__force u32)delta));
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uh->check = gso_make_checksum(skb, ~uh->check);
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if (uh->check == 0)
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uh->check = CSUM_MANGLED_0;
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}
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skb->protocol = protocol;
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} while ((skb = skb->next));
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out:
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return segs;
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}
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struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
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netdev_features_t features,
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bool is_ipv6)
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{
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__be16 protocol = skb->protocol;
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const struct net_offload **offloads;
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const struct net_offload *ops;
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struct sk_buff *segs = ERR_PTR(-EINVAL);
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struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
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netdev_features_t features);
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rcu_read_lock();
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switch (skb->inner_protocol_type) {
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case ENCAP_TYPE_ETHER:
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protocol = skb->inner_protocol;
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gso_inner_segment = skb_mac_gso_segment;
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break;
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case ENCAP_TYPE_IPPROTO:
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offloads = is_ipv6 ? inet6_offloads : inet_offloads;
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ops = rcu_dereference(offloads[skb->inner_ipproto]);
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if (!ops || !ops->callbacks.gso_segment)
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goto out_unlock;
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gso_inner_segment = ops->callbacks.gso_segment;
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break;
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default:
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goto out_unlock;
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}
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segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
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protocol);
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out_unlock:
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rcu_read_unlock();
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return segs;
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}
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static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
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netdev_features_t features)
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{
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struct sk_buff *segs = ERR_PTR(-EINVAL);
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unsigned int mss;
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__wsum csum;
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struct udphdr *uh;
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struct iphdr *iph;
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if (skb->encapsulation &&
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(skb_shinfo(skb)->gso_type &
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(SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
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segs = skb_udp_tunnel_segment(skb, features, false);
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goto out;
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}
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if (!pskb_may_pull(skb, sizeof(struct udphdr)))
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goto out;
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mss = skb_shinfo(skb)->gso_size;
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if (unlikely(skb->len <= mss))
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goto out;
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if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
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/* Packet is from an untrusted source, reset gso_segs. */
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int type = skb_shinfo(skb)->gso_type;
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if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
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SKB_GSO_UDP_TUNNEL |
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SKB_GSO_UDP_TUNNEL_CSUM |
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SKB_GSO_IPIP |
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SKB_GSO_GRE | SKB_GSO_GRE_CSUM |
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SKB_GSO_MPLS) ||
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!(type & (SKB_GSO_UDP))))
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goto out;
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skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
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segs = NULL;
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goto out;
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}
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/* Do software UFO. Complete and fill in the UDP checksum as
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* HW cannot do checksum of UDP packets sent as multiple
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* IP fragments.
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*/
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uh = udp_hdr(skb);
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iph = ip_hdr(skb);
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uh->check = 0;
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csum = skb_checksum(skb, 0, skb->len, 0);
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uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
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if (uh->check == 0)
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uh->check = CSUM_MANGLED_0;
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skb->ip_summed = CHECKSUM_NONE;
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/* Fragment the skb. IP headers of the fragments are updated in
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* inet_gso_segment()
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*/
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segs = skb_segment(skb, features);
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out:
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return segs;
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}
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int udp_add_offload(struct udp_offload *uo)
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{
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struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC);
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if (!new_offload)
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return -ENOMEM;
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new_offload->offload = uo;
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spin_lock(&udp_offload_lock);
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new_offload->next = udp_offload_base;
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rcu_assign_pointer(udp_offload_base, new_offload);
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spin_unlock(&udp_offload_lock);
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return 0;
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}
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EXPORT_SYMBOL(udp_add_offload);
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static void udp_offload_free_routine(struct rcu_head *head)
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{
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struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
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kfree(ou_priv);
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}
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void udp_del_offload(struct udp_offload *uo)
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{
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struct udp_offload_priv __rcu **head = &udp_offload_base;
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struct udp_offload_priv *uo_priv;
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spin_lock(&udp_offload_lock);
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uo_priv = udp_deref_protected(*head);
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for (; uo_priv != NULL;
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uo_priv = udp_deref_protected(*head)) {
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if (uo_priv->offload == uo) {
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rcu_assign_pointer(*head,
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udp_deref_protected(uo_priv->next));
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goto unlock;
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}
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head = &uo_priv->next;
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}
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pr_warn("udp_del_offload: didn't find offload for port %d\n", ntohs(uo->port));
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unlock:
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spin_unlock(&udp_offload_lock);
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if (uo_priv != NULL)
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call_rcu(&uo_priv->rcu, udp_offload_free_routine);
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}
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EXPORT_SYMBOL(udp_del_offload);
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struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
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struct udphdr *uh)
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{
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struct udp_offload_priv *uo_priv;
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struct sk_buff *p, **pp = NULL;
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struct udphdr *uh2;
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unsigned int off = skb_gro_offset(skb);
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int flush = 1;
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if (NAPI_GRO_CB(skb)->udp_mark ||
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(skb->ip_summed != CHECKSUM_PARTIAL &&
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NAPI_GRO_CB(skb)->csum_cnt == 0 &&
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!NAPI_GRO_CB(skb)->csum_valid))
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goto out;
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/* mark that this skb passed once through the udp gro layer */
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NAPI_GRO_CB(skb)->udp_mark = 1;
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rcu_read_lock();
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uo_priv = rcu_dereference(udp_offload_base);
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for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
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if (uo_priv->offload->port == uh->dest &&
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uo_priv->offload->callbacks.gro_receive)
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goto unflush;
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}
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goto out_unlock;
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unflush:
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flush = 0;
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for (p = *head; p; p = p->next) {
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if (!NAPI_GRO_CB(p)->same_flow)
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continue;
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uh2 = (struct udphdr *)(p->data + off);
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/* Match ports and either checksums are either both zero
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* or nonzero.
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*/
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if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
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(!uh->check ^ !uh2->check)) {
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NAPI_GRO_CB(p)->same_flow = 0;
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continue;
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}
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}
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skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
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skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
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NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
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pp = uo_priv->offload->callbacks.gro_receive(head, skb);
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out_unlock:
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rcu_read_unlock();
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out:
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NAPI_GRO_CB(skb)->flush |= flush;
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return pp;
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}
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static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
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struct sk_buff *skb)
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{
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struct udphdr *uh = udp_gro_udphdr(skb);
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if (unlikely(!uh))
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goto flush;
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/* Don't bother verifying checksum if we're going to flush anyway. */
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if (NAPI_GRO_CB(skb)->flush)
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goto skip;
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if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
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inet_gro_compute_pseudo))
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goto flush;
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else if (uh->check)
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skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
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inet_gro_compute_pseudo);
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skip:
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NAPI_GRO_CB(skb)->is_ipv6 = 0;
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return udp_gro_receive(head, skb, uh);
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flush:
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NAPI_GRO_CB(skb)->flush = 1;
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return NULL;
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}
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int udp_gro_complete(struct sk_buff *skb, int nhoff)
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{
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struct udp_offload_priv *uo_priv;
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__be16 newlen = htons(skb->len - nhoff);
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struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
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int err = -ENOSYS;
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uh->len = newlen;
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rcu_read_lock();
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uo_priv = rcu_dereference(udp_offload_base);
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for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
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if (uo_priv->offload->port == uh->dest &&
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uo_priv->offload->callbacks.gro_complete)
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break;
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}
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if (uo_priv != NULL) {
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NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
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err = uo_priv->offload->callbacks.gro_complete(skb, nhoff + sizeof(struct udphdr));
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}
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rcu_read_unlock();
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return err;
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}
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static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
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{
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const struct iphdr *iph = ip_hdr(skb);
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struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
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if (uh->check)
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uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
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iph->daddr, 0);
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return udp_gro_complete(skb, nhoff);
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}
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static const struct net_offload udpv4_offload = {
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.callbacks = {
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.gso_segment = udp4_ufo_fragment,
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.gro_receive = udp4_gro_receive,
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.gro_complete = udp4_gro_complete,
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},
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};
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int __init udpv4_offload_init(void)
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{
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return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
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}
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