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 (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP)) 46 goto out; 47 48 if (!pskb_may_pull(skb, sizeof(struct udphdr))) 49 goto out; 50 51 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot 52 * do checksum of UDP packets sent as multiple IP fragments. 53 */ 54 55 uh = udp_hdr(skb); 56 ipv6h = ipv6_hdr(skb); 57 58 uh->check = 0; 59 csum = skb_checksum(skb, 0, skb->len, 0); 60 uh->check = udp_v6_check(skb->len, &ipv6h->saddr, 61 &ipv6h->daddr, csum); 62 if (uh->check == 0) 63 uh->check = CSUM_MANGLED_0; 64 65 skb->ip_summed = CHECKSUM_UNNECESSARY; 66 67 /* If there is no outer header we can fake a checksum offload 68 * due to the fact that we have already done the checksum in 69 * software prior to segmenting the frame. 70 */ 71 if (!skb->encap_hdr_csum) 72 features |= NETIF_F_HW_CSUM; 73 74 /* Check if there is enough headroom to insert fragment header. */ 75 tnl_hlen = skb_tnl_header_len(skb); 76 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) { 77 if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz)) 78 goto out; 79 } 80 81 /* Find the unfragmentable header and shift it left by frag_hdr_sz 82 * bytes to insert fragment header. 83 */ 84 err = ip6_find_1stfragopt(skb, &prevhdr); 85 if (err < 0) 86 return ERR_PTR(err); 87 unfrag_ip6hlen = err; 88 nexthdr = *prevhdr; 89 *prevhdr = NEXTHDR_FRAGMENT; 90 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) + 91 unfrag_ip6hlen + tnl_hlen; 92 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset; 93 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len); 94 95 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz; 96 skb->mac_header -= frag_hdr_sz; 97 skb->network_header -= frag_hdr_sz; 98 99 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen); 100 fptr->nexthdr = nexthdr; 101 fptr->reserved = 0; 102 fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb); 103 104 /* Fragment the skb. ipv6 header and the remaining fields of the 105 * fragment header are updated in ipv6_gso_segment() 106 */ 107 segs = skb_segment(skb, features); 108 } 109 110 out: 111 return segs; 112 } 113 114 static struct sk_buff **udp6_gro_receive(struct sk_buff **head, 115 struct sk_buff *skb) 116 { 117 struct udphdr *uh = udp_gro_udphdr(skb); 118 119 if (unlikely(!uh)) 120 goto flush; 121 122 /* Don't bother verifying checksum if we're going to flush anyway. */ 123 if (NAPI_GRO_CB(skb)->flush) 124 goto skip; 125 126 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 127 ip6_gro_compute_pseudo)) 128 goto flush; 129 else if (uh->check) 130 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 131 ip6_gro_compute_pseudo); 132 133 skip: 134 NAPI_GRO_CB(skb)->is_ipv6 = 1; 135 return udp_gro_receive(head, skb, uh, udp6_lib_lookup_skb); 136 137 flush: 138 NAPI_GRO_CB(skb)->flush = 1; 139 return NULL; 140 } 141 142 static int udp6_gro_complete(struct sk_buff *skb, int nhoff) 143 { 144 const struct ipv6hdr *ipv6h = ipv6_hdr(skb); 145 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 146 147 if (uh->check) { 148 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM; 149 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr, 150 &ipv6h->daddr, 0); 151 } else { 152 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL; 153 } 154 155 return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb); 156 } 157 158 static const struct net_offload udpv6_offload = { 159 .callbacks = { 160 .gso_segment = udp6_ufo_fragment, 161 .gro_receive = udp6_gro_receive, 162 .gro_complete = udp6_gro_complete, 163 }, 164 }; 165 166 int udpv6_offload_init(void) 167 { 168 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP); 169 } 170 171 int udpv6_offload_exit(void) 172 { 173 return inet6_del_offload(&udpv6_offload, IPPROTO_UDP); 174 } 175