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 ipv6h = ipv6_hdr(skb); 28 uh = udp_hdr(skb); 29 30 uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len, 31 IPPROTO_UDP, 0); 32 skb->csum_start = skb_transport_header(skb) - skb->head; 33 skb->csum_offset = offsetof(struct udphdr, check); 34 skb->ip_summed = CHECKSUM_PARTIAL; 35 return 0; 36 } 37 38 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, 39 netdev_features_t features) 40 { 41 struct sk_buff *segs = ERR_PTR(-EINVAL); 42 unsigned int mss; 43 unsigned int unfrag_ip6hlen, unfrag_len; 44 struct frag_hdr *fptr; 45 u8 *mac_start, *prevhdr; 46 u8 nexthdr; 47 u8 frag_hdr_sz = sizeof(struct frag_hdr); 48 int offset; 49 __wsum csum; 50 51 mss = skb_shinfo(skb)->gso_size; 52 if (unlikely(skb->len <= mss)) 53 goto out; 54 55 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 56 /* Packet is from an untrusted source, reset gso_segs. */ 57 int type = skb_shinfo(skb)->gso_type; 58 59 if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY | 60 SKB_GSO_GRE) || 61 !(type & (SKB_GSO_UDP)))) 62 goto out; 63 64 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 65 66 segs = NULL; 67 goto out; 68 } 69 70 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot 71 * do checksum of UDP packets sent as multiple IP fragments. 72 */ 73 offset = skb_checksum_start_offset(skb); 74 csum = skb_checksum(skb, offset, skb->len - offset, 0); 75 offset += skb->csum_offset; 76 *(__sum16 *)(skb->data + offset) = csum_fold(csum); 77 skb->ip_summed = CHECKSUM_NONE; 78 79 /* Check if there is enough headroom to insert fragment header. */ 80 if ((skb_mac_header(skb) < skb->head + frag_hdr_sz) && 81 pskb_expand_head(skb, frag_hdr_sz, 0, GFP_ATOMIC)) 82 goto out; 83 84 /* Find the unfragmentable header and shift it left by frag_hdr_sz 85 * bytes to insert fragment header. 86 */ 87 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr); 88 nexthdr = *prevhdr; 89 *prevhdr = NEXTHDR_FRAGMENT; 90 unfrag_len = skb_network_header(skb) - skb_mac_header(skb) + 91 unfrag_ip6hlen; 92 mac_start = skb_mac_header(skb); 93 memmove(mac_start-frag_hdr_sz, mac_start, unfrag_len); 94 95 skb->mac_header -= frag_hdr_sz; 96 skb->network_header -= frag_hdr_sz; 97 98 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen); 99 fptr->nexthdr = nexthdr; 100 fptr->reserved = 0; 101 ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb)); 102 103 /* Fragment the skb. ipv6 header and the remaining fields of the 104 * fragment header are updated in ipv6_gso_segment() 105 */ 106 segs = skb_segment(skb, features); 107 108 out: 109 return segs; 110 } 111 static const struct net_offload udpv6_offload = { 112 .callbacks = { 113 .gso_send_check = udp6_ufo_send_check, 114 .gso_segment = udp6_ufo_fragment, 115 }, 116 }; 117 118 int __init udp_offload_init(void) 119 { 120 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP); 121 } 122