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_gso_segment(struct sk_buff *gso_skb, 21 netdev_features_t features) 22 { 23 if (!can_checksum_protocol(features, htons(ETH_P_IPV6))) 24 return ERR_PTR(-EIO); 25 26 return __udp_gso_segment(gso_skb, features); 27 } 28 29 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, 30 netdev_features_t features) 31 { 32 struct sk_buff *segs = ERR_PTR(-EINVAL); 33 unsigned int mss; 34 unsigned int unfrag_ip6hlen, unfrag_len; 35 struct frag_hdr *fptr; 36 u8 *packet_start, *prevhdr; 37 u8 nexthdr; 38 u8 frag_hdr_sz = sizeof(struct frag_hdr); 39 __wsum csum; 40 int tnl_hlen; 41 int err; 42 43 mss = skb_shinfo(skb)->gso_size; 44 if (unlikely(skb->len <= mss)) 45 goto out; 46 47 if (skb->encapsulation && skb_shinfo(skb)->gso_type & 48 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM)) 49 segs = skb_udp_tunnel_segment(skb, features, true); 50 else { 51 const struct ipv6hdr *ipv6h; 52 struct udphdr *uh; 53 54 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4))) 55 goto out; 56 57 if (!pskb_may_pull(skb, sizeof(struct udphdr))) 58 goto out; 59 60 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) 61 return __udp6_gso_segment(skb, features); 62 63 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot 64 * do checksum of UDP packets sent as multiple IP fragments. 65 */ 66 67 uh = udp_hdr(skb); 68 ipv6h = ipv6_hdr(skb); 69 70 uh->check = 0; 71 csum = skb_checksum(skb, 0, skb->len, 0); 72 uh->check = udp_v6_check(skb->len, &ipv6h->saddr, 73 &ipv6h->daddr, csum); 74 if (uh->check == 0) 75 uh->check = CSUM_MANGLED_0; 76 77 skb->ip_summed = CHECKSUM_UNNECESSARY; 78 79 /* If there is no outer header we can fake a checksum offload 80 * due to the fact that we have already done the checksum in 81 * software prior to segmenting the frame. 82 */ 83 if (!skb->encap_hdr_csum) 84 features |= NETIF_F_HW_CSUM; 85 86 /* Check if there is enough headroom to insert fragment header. */ 87 tnl_hlen = skb_tnl_header_len(skb); 88 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) { 89 if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz)) 90 goto out; 91 } 92 93 /* Find the unfragmentable header and shift it left by frag_hdr_sz 94 * bytes to insert fragment header. 95 */ 96 err = ip6_find_1stfragopt(skb, &prevhdr); 97 if (err < 0) 98 return ERR_PTR(err); 99 unfrag_ip6hlen = err; 100 nexthdr = *prevhdr; 101 *prevhdr = NEXTHDR_FRAGMENT; 102 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) + 103 unfrag_ip6hlen + tnl_hlen; 104 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset; 105 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len); 106 107 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz; 108 skb->mac_header -= frag_hdr_sz; 109 skb->network_header -= frag_hdr_sz; 110 111 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen); 112 fptr->nexthdr = nexthdr; 113 fptr->reserved = 0; 114 fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb); 115 116 /* Fragment the skb. ipv6 header and the remaining fields of the 117 * fragment header are updated in ipv6_gso_segment() 118 */ 119 segs = skb_segment(skb, features); 120 } 121 122 out: 123 return segs; 124 } 125 126 static struct sk_buff **udp6_gro_receive(struct sk_buff **head, 127 struct sk_buff *skb) 128 { 129 struct udphdr *uh = udp_gro_udphdr(skb); 130 131 if (unlikely(!uh)) 132 goto flush; 133 134 /* Don't bother verifying checksum if we're going to flush anyway. */ 135 if (NAPI_GRO_CB(skb)->flush) 136 goto skip; 137 138 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 139 ip6_gro_compute_pseudo)) 140 goto flush; 141 else if (uh->check) 142 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 143 ip6_gro_compute_pseudo); 144 145 skip: 146 NAPI_GRO_CB(skb)->is_ipv6 = 1; 147 return udp_gro_receive(head, skb, uh, udp6_lib_lookup_skb); 148 149 flush: 150 NAPI_GRO_CB(skb)->flush = 1; 151 return NULL; 152 } 153 154 static int udp6_gro_complete(struct sk_buff *skb, int nhoff) 155 { 156 const struct ipv6hdr *ipv6h = ipv6_hdr(skb); 157 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 158 159 if (uh->check) { 160 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM; 161 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr, 162 &ipv6h->daddr, 0); 163 } else { 164 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL; 165 } 166 167 return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb); 168 } 169 170 static const struct net_offload udpv6_offload = { 171 .callbacks = { 172 .gso_segment = udp6_ufo_fragment, 173 .gro_receive = udp6_gro_receive, 174 .gro_complete = udp6_gro_complete, 175 }, 176 }; 177 178 int udpv6_offload_init(void) 179 { 180 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP); 181 } 182 183 int udpv6_offload_exit(void) 184 { 185 return inet6_del_offload(&udpv6_offload, IPPROTO_UDP); 186 } 187