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 /* UDP Tunnel offload on ipv6 is not yet supported. */ 25 if (skb->encapsulation) 26 return -EINVAL; 27 28 if (!pskb_may_pull(skb, sizeof(*uh))) 29 return -EINVAL; 30 31 ipv6h = ipv6_hdr(skb); 32 uh = udp_hdr(skb); 33 34 uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len, 35 IPPROTO_UDP, 0); 36 skb->csum_start = skb_transport_header(skb) - skb->head; 37 skb->csum_offset = offsetof(struct udphdr, check); 38 skb->ip_summed = CHECKSUM_PARTIAL; 39 return 0; 40 } 41 42 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, 43 netdev_features_t features) 44 { 45 struct sk_buff *segs = ERR_PTR(-EINVAL); 46 unsigned int mss; 47 unsigned int unfrag_ip6hlen, unfrag_len; 48 struct frag_hdr *fptr; 49 u8 *packet_start, *prevhdr; 50 u8 nexthdr; 51 u8 frag_hdr_sz = sizeof(struct frag_hdr); 52 int offset; 53 __wsum csum; 54 int tnl_hlen; 55 56 mss = skb_shinfo(skb)->gso_size; 57 if (unlikely(skb->len <= mss)) 58 goto out; 59 60 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 61 /* Packet is from an untrusted source, reset gso_segs. */ 62 int type = skb_shinfo(skb)->gso_type; 63 64 if (unlikely(type & ~(SKB_GSO_UDP | 65 SKB_GSO_DODGY | 66 SKB_GSO_UDP_TUNNEL | 67 SKB_GSO_GRE) || 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 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot 78 * do checksum of UDP packets sent as multiple IP fragments. 79 */ 80 offset = skb_checksum_start_offset(skb); 81 csum = skb_checksum(skb, offset, skb->len - offset, 0); 82 offset += skb->csum_offset; 83 *(__sum16 *)(skb->data + offset) = csum_fold(csum); 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_headroom(skb) < (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 ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb)); 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 out: 119 return segs; 120 } 121 static const struct net_offload udpv6_offload = { 122 .callbacks = { 123 .gso_send_check = udp6_ufo_send_check, 124 .gso_segment = udp6_ufo_fragment, 125 }, 126 }; 127 128 int __init udp_offload_init(void) 129 { 130 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP); 131 } 132