1 /* 2 * IPV4 GSO/GRO offload support 3 * Linux INET 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 * UDPv4 GSO support 11 */ 12 13 #include <linux/skbuff.h> 14 #include <net/udp.h> 15 #include <net/protocol.h> 16 17 static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb, 18 netdev_features_t features, 19 struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb, 20 netdev_features_t features), 21 __be16 new_protocol, bool is_ipv6) 22 { 23 int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb); 24 bool remcsum, need_csum, offload_csum, gso_partial; 25 struct sk_buff *segs = ERR_PTR(-EINVAL); 26 struct udphdr *uh = udp_hdr(skb); 27 u16 mac_offset = skb->mac_header; 28 __be16 protocol = skb->protocol; 29 u16 mac_len = skb->mac_len; 30 int udp_offset, outer_hlen; 31 __wsum partial; 32 bool need_ipsec; 33 34 if (unlikely(!pskb_may_pull(skb, tnl_hlen))) 35 goto out; 36 37 /* Adjust partial header checksum to negate old length. 38 * We cannot rely on the value contained in uh->len as it is 39 * possible that the actual value exceeds the boundaries of the 40 * 16 bit length field due to the header being added outside of an 41 * IP or IPv6 frame that was already limited to 64K - 1. 42 */ 43 if (skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL) 44 partial = (__force __wsum)uh->len; 45 else 46 partial = (__force __wsum)htonl(skb->len); 47 partial = csum_sub(csum_unfold(uh->check), partial); 48 49 /* setup inner skb. */ 50 skb->encapsulation = 0; 51 SKB_GSO_CB(skb)->encap_level = 0; 52 __skb_pull(skb, tnl_hlen); 53 skb_reset_mac_header(skb); 54 skb_set_network_header(skb, skb_inner_network_offset(skb)); 55 skb->mac_len = skb_inner_network_offset(skb); 56 skb->protocol = new_protocol; 57 58 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM); 59 skb->encap_hdr_csum = need_csum; 60 61 remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM); 62 skb->remcsum_offload = remcsum; 63 64 need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb)); 65 /* Try to offload checksum if possible */ 66 offload_csum = !!(need_csum && 67 !need_ipsec && 68 (skb->dev->features & 69 (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) : 70 (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM)))); 71 72 features &= skb->dev->hw_enc_features; 73 74 /* The only checksum offload we care about from here on out is the 75 * outer one so strip the existing checksum feature flags and 76 * instead set the flag based on our outer checksum offload value. 77 */ 78 if (remcsum) { 79 features &= ~NETIF_F_CSUM_MASK; 80 if (!need_csum || offload_csum) 81 features |= NETIF_F_HW_CSUM; 82 } 83 84 /* segment inner packet. */ 85 segs = gso_inner_segment(skb, features); 86 if (IS_ERR_OR_NULL(segs)) { 87 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset, 88 mac_len); 89 goto out; 90 } 91 92 gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL); 93 94 outer_hlen = skb_tnl_header_len(skb); 95 udp_offset = outer_hlen - tnl_hlen; 96 skb = segs; 97 do { 98 unsigned int len; 99 100 if (remcsum) 101 skb->ip_summed = CHECKSUM_NONE; 102 103 /* Set up inner headers if we are offloading inner checksum */ 104 if (skb->ip_summed == CHECKSUM_PARTIAL) { 105 skb_reset_inner_headers(skb); 106 skb->encapsulation = 1; 107 } 108 109 skb->mac_len = mac_len; 110 skb->protocol = protocol; 111 112 __skb_push(skb, outer_hlen); 113 skb_reset_mac_header(skb); 114 skb_set_network_header(skb, mac_len); 115 skb_set_transport_header(skb, udp_offset); 116 len = skb->len - udp_offset; 117 uh = udp_hdr(skb); 118 119 /* If we are only performing partial GSO the inner header 120 * will be using a length value equal to only one MSS sized 121 * segment instead of the entire frame. 122 */ 123 if (gso_partial) { 124 uh->len = htons(skb_shinfo(skb)->gso_size + 125 SKB_GSO_CB(skb)->data_offset + 126 skb->head - (unsigned char *)uh); 127 } else { 128 uh->len = htons(len); 129 } 130 131 if (!need_csum) 132 continue; 133 134 uh->check = ~csum_fold(csum_add(partial, 135 (__force __wsum)htonl(len))); 136 137 if (skb->encapsulation || !offload_csum) { 138 uh->check = gso_make_checksum(skb, ~uh->check); 139 if (uh->check == 0) 140 uh->check = CSUM_MANGLED_0; 141 } else { 142 skb->ip_summed = CHECKSUM_PARTIAL; 143 skb->csum_start = skb_transport_header(skb) - skb->head; 144 skb->csum_offset = offsetof(struct udphdr, check); 145 } 146 } while ((skb = skb->next)); 147 out: 148 return segs; 149 } 150 151 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb, 152 netdev_features_t features, 153 bool is_ipv6) 154 { 155 __be16 protocol = skb->protocol; 156 const struct net_offload **offloads; 157 const struct net_offload *ops; 158 struct sk_buff *segs = ERR_PTR(-EINVAL); 159 struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb, 160 netdev_features_t features); 161 162 rcu_read_lock(); 163 164 switch (skb->inner_protocol_type) { 165 case ENCAP_TYPE_ETHER: 166 protocol = skb->inner_protocol; 167 gso_inner_segment = skb_mac_gso_segment; 168 break; 169 case ENCAP_TYPE_IPPROTO: 170 offloads = is_ipv6 ? inet6_offloads : inet_offloads; 171 ops = rcu_dereference(offloads[skb->inner_ipproto]); 172 if (!ops || !ops->callbacks.gso_segment) 173 goto out_unlock; 174 gso_inner_segment = ops->callbacks.gso_segment; 175 break; 176 default: 177 goto out_unlock; 178 } 179 180 segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment, 181 protocol, is_ipv6); 182 183 out_unlock: 184 rcu_read_unlock(); 185 186 return segs; 187 } 188 EXPORT_SYMBOL(skb_udp_tunnel_segment); 189 190 static struct sk_buff *udp4_tunnel_segment(struct sk_buff *skb, 191 netdev_features_t features) 192 { 193 struct sk_buff *segs = ERR_PTR(-EINVAL); 194 195 if (skb->encapsulation && 196 (skb_shinfo(skb)->gso_type & 197 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) 198 segs = skb_udp_tunnel_segment(skb, features, false); 199 200 return segs; 201 } 202 203 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb, 204 struct udphdr *uh, udp_lookup_t lookup) 205 { 206 struct sk_buff *p, **pp = NULL; 207 struct udphdr *uh2; 208 unsigned int off = skb_gro_offset(skb); 209 int flush = 1; 210 struct sock *sk; 211 212 if (NAPI_GRO_CB(skb)->encap_mark || 213 (skb->ip_summed != CHECKSUM_PARTIAL && 214 NAPI_GRO_CB(skb)->csum_cnt == 0 && 215 !NAPI_GRO_CB(skb)->csum_valid)) 216 goto out; 217 218 /* mark that this skb passed once through the tunnel gro layer */ 219 NAPI_GRO_CB(skb)->encap_mark = 1; 220 221 rcu_read_lock(); 222 sk = (*lookup)(skb, uh->source, uh->dest); 223 224 if (sk && udp_sk(sk)->gro_receive) 225 goto unflush; 226 goto out_unlock; 227 228 unflush: 229 flush = 0; 230 231 for (p = *head; p; p = p->next) { 232 if (!NAPI_GRO_CB(p)->same_flow) 233 continue; 234 235 uh2 = (struct udphdr *)(p->data + off); 236 237 /* Match ports and either checksums are either both zero 238 * or nonzero. 239 */ 240 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) || 241 (!uh->check ^ !uh2->check)) { 242 NAPI_GRO_CB(p)->same_flow = 0; 243 continue; 244 } 245 } 246 247 skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */ 248 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); 249 pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb); 250 251 out_unlock: 252 rcu_read_unlock(); 253 out: 254 NAPI_GRO_CB(skb)->flush |= flush; 255 return pp; 256 } 257 EXPORT_SYMBOL(udp_gro_receive); 258 259 static struct sk_buff **udp4_gro_receive(struct sk_buff **head, 260 struct sk_buff *skb) 261 { 262 struct udphdr *uh = udp_gro_udphdr(skb); 263 264 if (unlikely(!uh)) 265 goto flush; 266 267 /* Don't bother verifying checksum if we're going to flush anyway. */ 268 if (NAPI_GRO_CB(skb)->flush) 269 goto skip; 270 271 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 272 inet_gro_compute_pseudo)) 273 goto flush; 274 else if (uh->check) 275 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 276 inet_gro_compute_pseudo); 277 skip: 278 NAPI_GRO_CB(skb)->is_ipv6 = 0; 279 return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb); 280 281 flush: 282 NAPI_GRO_CB(skb)->flush = 1; 283 return NULL; 284 } 285 286 int udp_gro_complete(struct sk_buff *skb, int nhoff, 287 udp_lookup_t lookup) 288 { 289 __be16 newlen = htons(skb->len - nhoff); 290 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 291 int err = -ENOSYS; 292 struct sock *sk; 293 294 uh->len = newlen; 295 296 /* Set encapsulation before calling into inner gro_complete() functions 297 * to make them set up the inner offsets. 298 */ 299 skb->encapsulation = 1; 300 301 rcu_read_lock(); 302 sk = (*lookup)(skb, uh->source, uh->dest); 303 if (sk && udp_sk(sk)->gro_complete) 304 err = udp_sk(sk)->gro_complete(sk, skb, 305 nhoff + sizeof(struct udphdr)); 306 rcu_read_unlock(); 307 308 if (skb->remcsum_offload) 309 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM; 310 311 return err; 312 } 313 EXPORT_SYMBOL(udp_gro_complete); 314 315 static int udp4_gro_complete(struct sk_buff *skb, int nhoff) 316 { 317 const struct iphdr *iph = ip_hdr(skb); 318 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 319 320 if (uh->check) { 321 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM; 322 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr, 323 iph->daddr, 0); 324 } else { 325 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL; 326 } 327 328 return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb); 329 } 330 331 static const struct net_offload udpv4_offload = { 332 .callbacks = { 333 .gso_segment = udp4_tunnel_segment, 334 .gro_receive = udp4_gro_receive, 335 .gro_complete = udp4_gro_complete, 336 }, 337 }; 338 339 int __init udpv4_offload_init(void) 340 { 341 return inet_add_offload(&udpv4_offload, IPPROTO_UDP); 342 } 343