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 33 mss = skb_shinfo(skb)->gso_size; 34 if (unlikely(skb->len <= mss)) 35 goto out; 36 37 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 38 /* Packet is from an untrusted source, reset gso_segs. */ 39 int type = skb_shinfo(skb)->gso_type; 40 41 if (unlikely(type & ~(SKB_GSO_UDP | 42 SKB_GSO_DODGY | 43 SKB_GSO_UDP_TUNNEL | 44 SKB_GSO_UDP_TUNNEL_CSUM | 45 SKB_GSO_TUNNEL_REMCSUM | 46 SKB_GSO_GRE | 47 SKB_GSO_GRE_CSUM | 48 SKB_GSO_IPIP | 49 SKB_GSO_SIT) || 50 !(type & (SKB_GSO_UDP)))) 51 goto out; 52 53 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 54 55 /* Set the IPv6 fragment id if not set yet */ 56 if (!skb_shinfo(skb)->ip6_frag_id) 57 ipv6_proxy_select_ident(dev_net(skb->dev), skb); 58 59 segs = NULL; 60 goto out; 61 } 62 63 if (skb->encapsulation && skb_shinfo(skb)->gso_type & 64 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM)) 65 segs = skb_udp_tunnel_segment(skb, features, true); 66 else { 67 const struct ipv6hdr *ipv6h; 68 struct udphdr *uh; 69 70 if (!pskb_may_pull(skb, sizeof(struct udphdr))) 71 goto out; 72 73 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot 74 * do checksum of UDP packets sent as multiple IP fragments. 75 */ 76 77 uh = udp_hdr(skb); 78 ipv6h = ipv6_hdr(skb); 79 80 uh->check = 0; 81 csum = skb_checksum(skb, 0, skb->len, 0); 82 uh->check = udp_v6_check(skb->len, &ipv6h->saddr, 83 &ipv6h->daddr, csum); 84 if (uh->check == 0) 85 uh->check = CSUM_MANGLED_0; 86 87 skb->ip_summed = CHECKSUM_NONE; 88 89 /* If there is no outer header we can fake a checksum offload 90 * due to the fact that we have already done the checksum in 91 * software prior to segmenting the frame. 92 */ 93 if (!skb->encap_hdr_csum) 94 features |= NETIF_F_HW_CSUM; 95 96 /* Check if there is enough headroom to insert fragment header. */ 97 tnl_hlen = skb_tnl_header_len(skb); 98 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) { 99 if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz)) 100 goto out; 101 } 102 103 /* Find the unfragmentable header and shift it left by frag_hdr_sz 104 * bytes to insert fragment header. 105 */ 106 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr); 107 nexthdr = *prevhdr; 108 *prevhdr = NEXTHDR_FRAGMENT; 109 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) + 110 unfrag_ip6hlen + tnl_hlen; 111 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset; 112 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len); 113 114 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz; 115 skb->mac_header -= frag_hdr_sz; 116 skb->network_header -= frag_hdr_sz; 117 118 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen); 119 fptr->nexthdr = nexthdr; 120 fptr->reserved = 0; 121 if (!skb_shinfo(skb)->ip6_frag_id) 122 ipv6_proxy_select_ident(dev_net(skb->dev), skb); 123 fptr->identification = skb_shinfo(skb)->ip6_frag_id; 124 125 /* Fragment the skb. ipv6 header and the remaining fields of the 126 * fragment header are updated in ipv6_gso_segment() 127 */ 128 segs = skb_segment(skb, features); 129 } 130 131 out: 132 return segs; 133 } 134 135 static struct sk_buff **udp6_gro_receive(struct sk_buff **head, 136 struct sk_buff *skb) 137 { 138 struct udphdr *uh = udp_gro_udphdr(skb); 139 140 if (unlikely(!uh)) 141 goto flush; 142 143 /* Don't bother verifying checksum if we're going to flush anyway. */ 144 if (NAPI_GRO_CB(skb)->flush) 145 goto skip; 146 147 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 148 ip6_gro_compute_pseudo)) 149 goto flush; 150 else if (uh->check) 151 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 152 ip6_gro_compute_pseudo); 153 154 skip: 155 NAPI_GRO_CB(skb)->is_ipv6 = 1; 156 return udp_gro_receive(head, skb, uh, udp6_lib_lookup_skb); 157 158 flush: 159 NAPI_GRO_CB(skb)->flush = 1; 160 return NULL; 161 } 162 163 static int udp6_gro_complete(struct sk_buff *skb, int nhoff) 164 { 165 const struct ipv6hdr *ipv6h = ipv6_hdr(skb); 166 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 167 168 if (uh->check) { 169 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM; 170 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr, 171 &ipv6h->daddr, 0); 172 } else { 173 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL; 174 } 175 176 return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb); 177 } 178 179 static const struct net_offload udpv6_offload = { 180 .callbacks = { 181 .gso_segment = udp6_ufo_fragment, 182 .gro_receive = udp6_gro_receive, 183 .gro_complete = udp6_gro_complete, 184 }, 185 }; 186 187 int udpv6_offload_init(void) 188 { 189 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP); 190 } 191 192 int udpv6_offload_exit(void) 193 { 194 return inet6_del_offload(&udpv6_offload, IPPROTO_UDP); 195 } 196