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