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 85 if (uh->check == 0) 86 uh->check = CSUM_MANGLED_0; 87 88 skb->ip_summed = CHECKSUM_NONE; 89 90 /* Check if there is enough headroom to insert fragment header. */ 91 tnl_hlen = skb_tnl_header_len(skb); 92 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) { 93 if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz)) 94 goto out; 95 } 96 97 /* Find the unfragmentable header and shift it left by frag_hdr_sz 98 * bytes to insert fragment header. 99 */ 100 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr); 101 nexthdr = *prevhdr; 102 *prevhdr = NEXTHDR_FRAGMENT; 103 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) + 104 unfrag_ip6hlen + tnl_hlen; 105 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset; 106 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len); 107 108 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz; 109 skb->mac_header -= frag_hdr_sz; 110 skb->network_header -= frag_hdr_sz; 111 112 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen); 113 fptr->nexthdr = nexthdr; 114 fptr->reserved = 0; 115 if (!skb_shinfo(skb)->ip6_frag_id) 116 ipv6_proxy_select_ident(dev_net(skb->dev), skb); 117 fptr->identification = skb_shinfo(skb)->ip6_frag_id; 118 119 /* Fragment the skb. ipv6 header and the remaining fields of the 120 * fragment header are updated in ipv6_gso_segment() 121 */ 122 segs = skb_segment(skb, features); 123 } 124 125 out: 126 return segs; 127 } 128 129 static struct sk_buff **udp6_gro_receive(struct sk_buff **head, 130 struct sk_buff *skb) 131 { 132 struct udphdr *uh = udp_gro_udphdr(skb); 133 134 if (unlikely(!uh)) 135 goto flush; 136 137 /* Don't bother verifying checksum if we're going to flush anyway. */ 138 if (NAPI_GRO_CB(skb)->flush) 139 goto skip; 140 141 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 142 ip6_gro_compute_pseudo)) 143 goto flush; 144 else if (uh->check) 145 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 146 ip6_gro_compute_pseudo); 147 148 skip: 149 NAPI_GRO_CB(skb)->is_ipv6 = 1; 150 return udp_gro_receive(head, skb, uh); 151 152 flush: 153 NAPI_GRO_CB(skb)->flush = 1; 154 return NULL; 155 } 156 157 static int udp6_gro_complete(struct sk_buff *skb, int nhoff) 158 { 159 const struct ipv6hdr *ipv6h = ipv6_hdr(skb); 160 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 161 162 if (uh->check) { 163 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM; 164 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr, 165 &ipv6h->daddr, 0); 166 } else { 167 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL; 168 } 169 170 return udp_gro_complete(skb, nhoff); 171 } 172 173 static const struct net_offload udpv6_offload = { 174 .callbacks = { 175 .gso_segment = udp6_ufo_fragment, 176 .gro_receive = udp6_gro_receive, 177 .gro_complete = udp6_gro_complete, 178 }, 179 }; 180 181 int __init udp_offload_init(void) 182 { 183 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP); 184 } 185