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 && skb_is_gso(skb)) { 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_ufo_fragment(struct sk_buff *skb, 191 netdev_features_t features) 192 { 193 struct sk_buff *segs = ERR_PTR(-EINVAL); 194 unsigned int mss; 195 __wsum csum; 196 struct udphdr *uh; 197 struct iphdr *iph; 198 199 if (skb->encapsulation && 200 (skb_shinfo(skb)->gso_type & 201 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) { 202 segs = skb_udp_tunnel_segment(skb, features, false); 203 goto out; 204 } 205 206 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP)) 207 goto out; 208 209 if (!pskb_may_pull(skb, sizeof(struct udphdr))) 210 goto out; 211 212 mss = skb_shinfo(skb)->gso_size; 213 if (unlikely(skb->len <= mss)) 214 goto out; 215 216 /* Do software UFO. Complete and fill in the UDP checksum as 217 * HW cannot do checksum of UDP packets sent as multiple 218 * IP fragments. 219 */ 220 221 uh = udp_hdr(skb); 222 iph = ip_hdr(skb); 223 224 uh->check = 0; 225 csum = skb_checksum(skb, 0, skb->len, 0); 226 uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum); 227 if (uh->check == 0) 228 uh->check = CSUM_MANGLED_0; 229 230 skb->ip_summed = CHECKSUM_UNNECESSARY; 231 232 /* If there is no outer header we can fake a checksum offload 233 * due to the fact that we have already done the checksum in 234 * software prior to segmenting the frame. 235 */ 236 if (!skb->encap_hdr_csum) 237 features |= NETIF_F_HW_CSUM; 238 239 /* Fragment the skb. IP headers of the fragments are updated in 240 * inet_gso_segment() 241 */ 242 segs = skb_segment(skb, features); 243 out: 244 return segs; 245 } 246 247 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb, 248 struct udphdr *uh, udp_lookup_t lookup) 249 { 250 struct sk_buff *p, **pp = NULL; 251 struct udphdr *uh2; 252 unsigned int off = skb_gro_offset(skb); 253 int flush = 1; 254 struct sock *sk; 255 256 if (NAPI_GRO_CB(skb)->encap_mark || 257 (skb->ip_summed != CHECKSUM_PARTIAL && 258 NAPI_GRO_CB(skb)->csum_cnt == 0 && 259 !NAPI_GRO_CB(skb)->csum_valid)) 260 goto out; 261 262 /* mark that this skb passed once through the tunnel gro layer */ 263 NAPI_GRO_CB(skb)->encap_mark = 1; 264 265 rcu_read_lock(); 266 sk = (*lookup)(skb, uh->source, uh->dest); 267 268 if (sk && udp_sk(sk)->gro_receive) 269 goto unflush; 270 goto out_unlock; 271 272 unflush: 273 flush = 0; 274 275 for (p = *head; p; p = p->next) { 276 if (!NAPI_GRO_CB(p)->same_flow) 277 continue; 278 279 uh2 = (struct udphdr *)(p->data + off); 280 281 /* Match ports and either checksums are either both zero 282 * or nonzero. 283 */ 284 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) || 285 (!uh->check ^ !uh2->check)) { 286 NAPI_GRO_CB(p)->same_flow = 0; 287 continue; 288 } 289 } 290 291 skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */ 292 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); 293 pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb); 294 295 out_unlock: 296 rcu_read_unlock(); 297 out: 298 NAPI_GRO_CB(skb)->flush |= flush; 299 return pp; 300 } 301 EXPORT_SYMBOL(udp_gro_receive); 302 303 static struct sk_buff **udp4_gro_receive(struct sk_buff **head, 304 struct sk_buff *skb) 305 { 306 struct udphdr *uh = udp_gro_udphdr(skb); 307 308 if (unlikely(!uh)) 309 goto flush; 310 311 /* Don't bother verifying checksum if we're going to flush anyway. */ 312 if (NAPI_GRO_CB(skb)->flush) 313 goto skip; 314 315 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 316 inet_gro_compute_pseudo)) 317 goto flush; 318 else if (uh->check) 319 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 320 inet_gro_compute_pseudo); 321 skip: 322 NAPI_GRO_CB(skb)->is_ipv6 = 0; 323 return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb); 324 325 flush: 326 NAPI_GRO_CB(skb)->flush = 1; 327 return NULL; 328 } 329 330 int udp_gro_complete(struct sk_buff *skb, int nhoff, 331 udp_lookup_t lookup) 332 { 333 __be16 newlen = htons(skb->len - nhoff); 334 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 335 int err = -ENOSYS; 336 struct sock *sk; 337 338 uh->len = newlen; 339 340 /* Set encapsulation before calling into inner gro_complete() functions 341 * to make them set up the inner offsets. 342 */ 343 skb->encapsulation = 1; 344 345 rcu_read_lock(); 346 sk = (*lookup)(skb, uh->source, uh->dest); 347 if (sk && udp_sk(sk)->gro_complete) 348 err = udp_sk(sk)->gro_complete(sk, skb, 349 nhoff + sizeof(struct udphdr)); 350 rcu_read_unlock(); 351 352 if (skb->remcsum_offload) 353 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM; 354 355 return err; 356 } 357 EXPORT_SYMBOL(udp_gro_complete); 358 359 static int udp4_gro_complete(struct sk_buff *skb, int nhoff) 360 { 361 const struct iphdr *iph = ip_hdr(skb); 362 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 363 364 if (uh->check) { 365 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM; 366 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr, 367 iph->daddr, 0); 368 } else { 369 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL; 370 } 371 372 return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb); 373 } 374 375 static const struct net_offload udpv4_offload = { 376 .callbacks = { 377 .gso_segment = udp4_ufo_fragment, 378 .gro_receive = udp4_gro_receive, 379 .gro_complete = udp4_gro_complete, 380 }, 381 }; 382 383 int __init udpv4_offload_init(void) 384 { 385 return inet_add_offload(&udpv4_offload, IPPROTO_UDP); 386 } 387