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