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 <net/protocol.h> 14 #include <net/ipv6.h> 15 #include <net/udp.h> 16 #include <net/ip6_checksum.h> 17 #include "ip6_offload.h" 18 19 static int udp6_ufo_send_check(struct sk_buff *skb) 20 { 21 const struct ipv6hdr *ipv6h; 22 struct udphdr *uh; 23 24 if (!pskb_may_pull(skb, sizeof(*uh))) 25 return -EINVAL; 26 27 if (likely(!skb->encapsulation)) { 28 ipv6h = ipv6_hdr(skb); 29 uh = udp_hdr(skb); 30 31 uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len, 32 IPPROTO_UDP, 0); 33 skb->csum_start = skb_transport_header(skb) - skb->head; 34 skb->csum_offset = offsetof(struct udphdr, check); 35 skb->ip_summed = CHECKSUM_PARTIAL; 36 } 37 38 return 0; 39 } 40 41 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, 42 netdev_features_t features) 43 { 44 struct sk_buff *segs = ERR_PTR(-EINVAL); 45 unsigned int mss; 46 unsigned int unfrag_ip6hlen, unfrag_len; 47 struct frag_hdr *fptr; 48 u8 *packet_start, *prevhdr; 49 u8 nexthdr; 50 u8 frag_hdr_sz = sizeof(struct frag_hdr); 51 int offset; 52 __wsum csum; 53 int tnl_hlen; 54 55 mss = skb_shinfo(skb)->gso_size; 56 if (unlikely(skb->len <= mss)) 57 goto out; 58 59 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 60 /* Packet is from an untrusted source, reset gso_segs. */ 61 int type = skb_shinfo(skb)->gso_type; 62 63 if (unlikely(type & ~(SKB_GSO_UDP | 64 SKB_GSO_DODGY | 65 SKB_GSO_UDP_TUNNEL | 66 SKB_GSO_UDP_TUNNEL_CSUM | 67 SKB_GSO_GRE | 68 SKB_GSO_GRE_CSUM | 69 SKB_GSO_IPIP | 70 SKB_GSO_SIT | 71 SKB_GSO_MPLS) || 72 !(type & (SKB_GSO_UDP)))) 73 goto out; 74 75 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 76 77 segs = NULL; 78 goto out; 79 } 80 81 if (skb->encapsulation && skb_shinfo(skb)->gso_type & 82 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM)) 83 segs = skb_udp_tunnel_segment(skb, features); 84 else { 85 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot 86 * do checksum of UDP packets sent as multiple IP fragments. 87 */ 88 offset = skb_checksum_start_offset(skb); 89 csum = skb_checksum(skb, offset, skb->len - offset, 0); 90 offset += skb->csum_offset; 91 *(__sum16 *)(skb->data + offset) = csum_fold(csum); 92 skb->ip_summed = CHECKSUM_NONE; 93 94 /* Check if there is enough headroom to insert fragment header. */ 95 tnl_hlen = skb_tnl_header_len(skb); 96 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) { 97 if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz)) 98 goto out; 99 } 100 101 /* Find the unfragmentable header and shift it left by frag_hdr_sz 102 * bytes to insert fragment header. 103 */ 104 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr); 105 nexthdr = *prevhdr; 106 *prevhdr = NEXTHDR_FRAGMENT; 107 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) + 108 unfrag_ip6hlen + tnl_hlen; 109 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset; 110 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len); 111 112 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz; 113 skb->mac_header -= frag_hdr_sz; 114 skb->network_header -= frag_hdr_sz; 115 116 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen); 117 fptr->nexthdr = nexthdr; 118 fptr->reserved = 0; 119 fptr->identification = skb_shinfo(skb)->ip6_frag_id; 120 121 /* Fragment the skb. ipv6 header and the remaining fields of the 122 * fragment header are updated in ipv6_gso_segment() 123 */ 124 segs = skb_segment(skb, features); 125 } 126 127 out: 128 return segs; 129 } 130 static const struct net_offload udpv6_offload = { 131 .callbacks = { 132 .gso_send_check = udp6_ufo_send_check, 133 .gso_segment = udp6_ufo_fragment, 134 }, 135 }; 136 137 int __init udp_offload_init(void) 138 { 139 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP); 140 } 141