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_GRE | 67 SKB_GSO_MPLS) || 68 !(type & (SKB_GSO_UDP)))) 69 goto out; 70 71 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 72 73 segs = NULL; 74 goto out; 75 } 76 77 if (skb->encapsulation && skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL) 78 segs = skb_udp_tunnel_segment(skb, features); 79 else { 80 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot 81 * do checksum of UDP packets sent as multiple IP fragments. 82 */ 83 offset = skb_checksum_start_offset(skb); 84 csum = skb_checksum(skb, offset, skb->len - offset, 0); 85 offset += skb->csum_offset; 86 *(__sum16 *)(skb->data + offset) = csum_fold(csum); 87 skb->ip_summed = CHECKSUM_NONE; 88 89 /* Check if there is enough headroom to insert fragment header. */ 90 tnl_hlen = skb_tnl_header_len(skb); 91 if (skb_headroom(skb) < (tnl_hlen + frag_hdr_sz)) { 92 if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz)) 93 goto out; 94 } 95 96 /* Find the unfragmentable header and shift it left by frag_hdr_sz 97 * bytes to insert fragment header. 98 */ 99 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr); 100 nexthdr = *prevhdr; 101 *prevhdr = NEXTHDR_FRAGMENT; 102 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) + 103 unfrag_ip6hlen + tnl_hlen; 104 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset; 105 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len); 106 107 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz; 108 skb->mac_header -= frag_hdr_sz; 109 skb->network_header -= frag_hdr_sz; 110 111 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen); 112 fptr->nexthdr = nexthdr; 113 fptr->reserved = 0; 114 ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb)); 115 116 /* Fragment the skb. ipv6 header and the remaining fields of the 117 * fragment header are updated in ipv6_gso_segment() 118 */ 119 segs = skb_segment(skb, features); 120 } 121 122 out: 123 return segs; 124 } 125 static const struct net_offload udpv6_offload = { 126 .callbacks = { 127 .gso_send_check = udp6_ufo_send_check, 128 .gso_segment = udp6_ufo_fragment, 129 }, 130 }; 131 132 int __init udp_offload_init(void) 133 { 134 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP); 135 } 136