1 /* 2 * IPV6 GSO/GRO offload support 3 * Linux INET6 implementation 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 8 * 2 of the License, or (at your option) any later version. 9 * 10 * UDPv6 GSO support 11 */ 12 #include <linux/skbuff.h> 13 #include <linux/netdevice.h> 14 #include <net/protocol.h> 15 #include <net/ipv6.h> 16 #include <net/udp.h> 17 #include <net/ip6_checksum.h> 18 #include "ip6_offload.h" 19 20 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, 21 netdev_features_t features) 22 { 23 struct sk_buff *segs = ERR_PTR(-EINVAL); 24 unsigned int mss; 25 unsigned int unfrag_ip6hlen, unfrag_len; 26 struct frag_hdr *fptr; 27 u8 *packet_start, *prevhdr; 28 u8 nexthdr; 29 u8 frag_hdr_sz = sizeof(struct frag_hdr); 30 __wsum csum; 31 int tnl_hlen; 32 int err; 33 34 mss = skb_shinfo(skb)->gso_size; 35 if (unlikely(skb->len <= mss)) 36 goto out; 37 38 if (skb->encapsulation && skb_shinfo(skb)->gso_type & 39 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM)) 40 segs = skb_udp_tunnel_segment(skb, features, true); 41 else { 42 const struct ipv6hdr *ipv6h; 43 struct udphdr *uh; 44 45 if (!pskb_may_pull(skb, sizeof(struct udphdr))) 46 goto out; 47 48 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot 49 * do checksum of UDP packets sent as multiple IP fragments. 50 */ 51 52 uh = udp_hdr(skb); 53 ipv6h = ipv6_hdr(skb); 54 55 uh->check = 0; 56 csum = skb_checksum(skb, 0, skb->len, 0); 57 uh->check = udp_v6_check(skb->len, &ipv6h->saddr, 58 &ipv6h->daddr, csum); 59 if (uh->check == 0) 60 uh->check = CSUM_MANGLED_0; 61 62 skb->ip_summed = CHECKSUM_UNNECESSARY; 63 64 /* If there is no outer header we can fake a checksum offload 65 * due to the fact that we have already done the checksum in 66 * software prior to segmenting the frame. 67 */ 68 if (!skb->encap_hdr_csum) 69 features |= NETIF_F_HW_CSUM; 70 71 /* Check if there is enough headroom to insert fragment header. */ 72 tnl_hlen = skb_tnl_header_len(skb); 73 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) { 74 if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz)) 75 goto out; 76 } 77 78 /* Find the unfragmentable header and shift it left by frag_hdr_sz 79 * bytes to insert fragment header. 80 */ 81 err = ip6_find_1stfragopt(skb, &prevhdr); 82 if (err < 0) 83 return ERR_PTR(err); 84 unfrag_ip6hlen = err; 85 nexthdr = *prevhdr; 86 *prevhdr = NEXTHDR_FRAGMENT; 87 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) + 88 unfrag_ip6hlen + tnl_hlen; 89 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset; 90 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len); 91 92 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz; 93 skb->mac_header -= frag_hdr_sz; 94 skb->network_header -= frag_hdr_sz; 95 96 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen); 97 fptr->nexthdr = nexthdr; 98 fptr->reserved = 0; 99 fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb); 100 101 /* Fragment the skb. ipv6 header and the remaining fields of the 102 * fragment header are updated in ipv6_gso_segment() 103 */ 104 segs = skb_segment(skb, features); 105 } 106 107 out: 108 return segs; 109 } 110 111 static struct sk_buff **udp6_gro_receive(struct sk_buff **head, 112 struct sk_buff *skb) 113 { 114 struct udphdr *uh = udp_gro_udphdr(skb); 115 116 if (unlikely(!uh)) 117 goto flush; 118 119 /* Don't bother verifying checksum if we're going to flush anyway. */ 120 if (NAPI_GRO_CB(skb)->flush) 121 goto skip; 122 123 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 124 ip6_gro_compute_pseudo)) 125 goto flush; 126 else if (uh->check) 127 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 128 ip6_gro_compute_pseudo); 129 130 skip: 131 NAPI_GRO_CB(skb)->is_ipv6 = 1; 132 return udp_gro_receive(head, skb, uh, udp6_lib_lookup_skb); 133 134 flush: 135 NAPI_GRO_CB(skb)->flush = 1; 136 return NULL; 137 } 138 139 static int udp6_gro_complete(struct sk_buff *skb, int nhoff) 140 { 141 const struct ipv6hdr *ipv6h = ipv6_hdr(skb); 142 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 143 144 if (uh->check) { 145 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM; 146 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr, 147 &ipv6h->daddr, 0); 148 } else { 149 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL; 150 } 151 152 return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb); 153 } 154 155 static const struct net_offload udpv6_offload = { 156 .callbacks = { 157 .gso_segment = udp6_ufo_fragment, 158 .gro_receive = udp6_gro_receive, 159 .gro_complete = udp6_gro_complete, 160 }, 161 }; 162 163 int udpv6_offload_init(void) 164 { 165 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP); 166 } 167 168 int udpv6_offload_exit(void) 169 { 170 return inet6_del_offload(&udpv6_offload, IPPROTO_UDP); 171 } 172