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_GRE | 46 SKB_GSO_GRE_CSUM | 47 SKB_GSO_IPIP | 48 SKB_GSO_SIT | 49 SKB_GSO_MPLS) || 50 !(type & (SKB_GSO_UDP)))) 51 goto out; 52 53 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 54 55 segs = NULL; 56 goto out; 57 } 58 59 if (skb->encapsulation && skb_shinfo(skb)->gso_type & 60 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM)) 61 segs = skb_udp_tunnel_segment(skb, features, true); 62 else { 63 const struct ipv6hdr *ipv6h; 64 struct udphdr *uh; 65 66 if (!pskb_may_pull(skb, sizeof(struct udphdr))) 67 goto out; 68 69 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot 70 * do checksum of UDP packets sent as multiple IP fragments. 71 */ 72 73 uh = udp_hdr(skb); 74 ipv6h = ipv6_hdr(skb); 75 76 uh->check = 0; 77 csum = skb_checksum(skb, 0, skb->len, 0); 78 uh->check = udp_v6_check(skb->len, &ipv6h->saddr, 79 &ipv6h->daddr, csum); 80 81 if (uh->check == 0) 82 uh->check = CSUM_MANGLED_0; 83 84 skb->ip_summed = CHECKSUM_NONE; 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 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr); 97 nexthdr = *prevhdr; 98 *prevhdr = NEXTHDR_FRAGMENT; 99 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) + 100 unfrag_ip6hlen + tnl_hlen; 101 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset; 102 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len); 103 104 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz; 105 skb->mac_header -= frag_hdr_sz; 106 skb->network_header -= frag_hdr_sz; 107 108 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen); 109 fptr->nexthdr = nexthdr; 110 fptr->reserved = 0; 111 fptr->identification = skb_shinfo(skb)->ip6_frag_id; 112 113 /* Fragment the skb. ipv6 header and the remaining fields of the 114 * fragment header are updated in ipv6_gso_segment() 115 */ 116 segs = skb_segment(skb, features); 117 } 118 119 out: 120 return segs; 121 } 122 123 static struct sk_buff **udp6_gro_receive(struct sk_buff **head, 124 struct sk_buff *skb) 125 { 126 struct udphdr *uh = udp_gro_udphdr(skb); 127 128 if (unlikely(!uh)) 129 goto flush; 130 131 /* Don't bother verifying checksum if we're going to flush anyway. */ 132 if (NAPI_GRO_CB(skb)->flush) 133 goto skip; 134 135 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 136 ip6_gro_compute_pseudo)) 137 goto flush; 138 else if (uh->check) 139 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 140 ip6_gro_compute_pseudo); 141 142 skip: 143 NAPI_GRO_CB(skb)->is_ipv6 = 1; 144 return udp_gro_receive(head, skb, uh); 145 146 flush: 147 NAPI_GRO_CB(skb)->flush = 1; 148 return NULL; 149 } 150 151 static int udp6_gro_complete(struct sk_buff *skb, int nhoff) 152 { 153 const struct ipv6hdr *ipv6h = ipv6_hdr(skb); 154 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 155 156 if (uh->check) 157 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr, 158 &ipv6h->daddr, 0); 159 160 return udp_gro_complete(skb, nhoff); 161 } 162 163 static const struct net_offload udpv6_offload = { 164 .callbacks = { 165 .gso_segment = udp6_ufo_fragment, 166 .gro_receive = udp6_gro_receive, 167 .gro_complete = udp6_gro_complete, 168 }, 169 }; 170 171 int __init udp_offload_init(void) 172 { 173 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP); 174 } 175