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, ufo, 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 ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP); 65 66 need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb)); 67 /* Try to offload checksum if possible */ 68 offload_csum = !!(need_csum && 69 !need_ipsec && 70 (skb->dev->features & 71 (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) : 72 (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM)))); 73 74 features &= skb->dev->hw_enc_features; 75 76 /* The only checksum offload we care about from here on out is the 77 * outer one so strip the existing checksum feature flags and 78 * instead set the flag based on our outer checksum offload value. 79 */ 80 if (remcsum || ufo) { 81 features &= ~NETIF_F_CSUM_MASK; 82 if (!need_csum || offload_csum) 83 features |= NETIF_F_HW_CSUM; 84 } 85 86 /* segment inner packet. */ 87 segs = gso_inner_segment(skb, features); 88 if (IS_ERR_OR_NULL(segs)) { 89 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset, 90 mac_len); 91 goto out; 92 } 93 94 gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL); 95 96 outer_hlen = skb_tnl_header_len(skb); 97 udp_offset = outer_hlen - tnl_hlen; 98 skb = segs; 99 do { 100 unsigned int len; 101 102 if (remcsum) 103 skb->ip_summed = CHECKSUM_NONE; 104 105 /* Set up inner headers if we are offloading inner checksum */ 106 if (skb->ip_summed == CHECKSUM_PARTIAL) { 107 skb_reset_inner_headers(skb); 108 skb->encapsulation = 1; 109 } 110 111 skb->mac_len = mac_len; 112 skb->protocol = protocol; 113 114 __skb_push(skb, outer_hlen); 115 skb_reset_mac_header(skb); 116 skb_set_network_header(skb, mac_len); 117 skb_set_transport_header(skb, udp_offset); 118 len = skb->len - udp_offset; 119 uh = udp_hdr(skb); 120 121 /* If we are only performing partial GSO the inner header 122 * will be using a length value equal to only one MSS sized 123 * segment instead of the entire frame. 124 */ 125 if (gso_partial) { 126 uh->len = htons(skb_shinfo(skb)->gso_size + 127 SKB_GSO_CB(skb)->data_offset + 128 skb->head - (unsigned char *)uh); 129 } else { 130 uh->len = htons(len); 131 } 132 133 if (!need_csum) 134 continue; 135 136 uh->check = ~csum_fold(csum_add(partial, 137 (__force __wsum)htonl(len))); 138 139 if (skb->encapsulation || !offload_csum) { 140 uh->check = gso_make_checksum(skb, ~uh->check); 141 if (uh->check == 0) 142 uh->check = CSUM_MANGLED_0; 143 } else { 144 skb->ip_summed = CHECKSUM_PARTIAL; 145 skb->csum_start = skb_transport_header(skb) - skb->head; 146 skb->csum_offset = offsetof(struct udphdr, check); 147 } 148 } while ((skb = skb->next)); 149 out: 150 return segs; 151 } 152 153 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb, 154 netdev_features_t features, 155 bool is_ipv6) 156 { 157 __be16 protocol = skb->protocol; 158 const struct net_offload **offloads; 159 const struct net_offload *ops; 160 struct sk_buff *segs = ERR_PTR(-EINVAL); 161 struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb, 162 netdev_features_t features); 163 164 rcu_read_lock(); 165 166 switch (skb->inner_protocol_type) { 167 case ENCAP_TYPE_ETHER: 168 protocol = skb->inner_protocol; 169 gso_inner_segment = skb_mac_gso_segment; 170 break; 171 case ENCAP_TYPE_IPPROTO: 172 offloads = is_ipv6 ? inet6_offloads : inet_offloads; 173 ops = rcu_dereference(offloads[skb->inner_ipproto]); 174 if (!ops || !ops->callbacks.gso_segment) 175 goto out_unlock; 176 gso_inner_segment = ops->callbacks.gso_segment; 177 break; 178 default: 179 goto out_unlock; 180 } 181 182 segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment, 183 protocol, is_ipv6); 184 185 out_unlock: 186 rcu_read_unlock(); 187 188 return segs; 189 } 190 EXPORT_SYMBOL(skb_udp_tunnel_segment); 191 192 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, 193 netdev_features_t features) 194 { 195 struct sk_buff *segs = ERR_PTR(-EINVAL); 196 unsigned int mss; 197 __wsum csum; 198 struct udphdr *uh; 199 struct iphdr *iph; 200 201 if (skb->encapsulation && 202 (skb_shinfo(skb)->gso_type & 203 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) { 204 segs = skb_udp_tunnel_segment(skb, features, false); 205 goto out; 206 } 207 208 if (!pskb_may_pull(skb, sizeof(struct udphdr))) 209 goto out; 210 211 mss = skb_shinfo(skb)->gso_size; 212 if (unlikely(skb->len <= mss)) 213 goto out; 214 215 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 216 /* Packet is from an untrusted source, reset gso_segs. */ 217 218 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 219 220 segs = NULL; 221 goto out; 222 } 223 224 /* Do software UFO. Complete and fill in the UDP checksum as 225 * HW cannot do checksum of UDP packets sent as multiple 226 * IP fragments. 227 */ 228 229 uh = udp_hdr(skb); 230 iph = ip_hdr(skb); 231 232 uh->check = 0; 233 csum = skb_checksum(skb, 0, skb->len, 0); 234 uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum); 235 if (uh->check == 0) 236 uh->check = CSUM_MANGLED_0; 237 238 skb->ip_summed = CHECKSUM_NONE; 239 240 /* If there is no outer header we can fake a checksum offload 241 * due to the fact that we have already done the checksum in 242 * software prior to segmenting the frame. 243 */ 244 if (!skb->encap_hdr_csum) 245 features |= NETIF_F_HW_CSUM; 246 247 /* Fragment the skb. IP headers of the fragments are updated in 248 * inet_gso_segment() 249 */ 250 segs = skb_segment(skb, features); 251 out: 252 return segs; 253 } 254 255 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb, 256 struct udphdr *uh, udp_lookup_t lookup) 257 { 258 struct sk_buff *p, **pp = NULL; 259 struct udphdr *uh2; 260 unsigned int off = skb_gro_offset(skb); 261 int flush = 1; 262 struct sock *sk; 263 264 if (NAPI_GRO_CB(skb)->encap_mark || 265 (skb->ip_summed != CHECKSUM_PARTIAL && 266 NAPI_GRO_CB(skb)->csum_cnt == 0 && 267 !NAPI_GRO_CB(skb)->csum_valid)) 268 goto out; 269 270 /* mark that this skb passed once through the tunnel gro layer */ 271 NAPI_GRO_CB(skb)->encap_mark = 1; 272 273 rcu_read_lock(); 274 sk = (*lookup)(skb, uh->source, uh->dest); 275 276 if (sk && udp_sk(sk)->gro_receive) 277 goto unflush; 278 goto out_unlock; 279 280 unflush: 281 flush = 0; 282 283 for (p = *head; p; p = p->next) { 284 if (!NAPI_GRO_CB(p)->same_flow) 285 continue; 286 287 uh2 = (struct udphdr *)(p->data + off); 288 289 /* Match ports and either checksums are either both zero 290 * or nonzero. 291 */ 292 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) || 293 (!uh->check ^ !uh2->check)) { 294 NAPI_GRO_CB(p)->same_flow = 0; 295 continue; 296 } 297 } 298 299 skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */ 300 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); 301 pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb); 302 303 out_unlock: 304 rcu_read_unlock(); 305 out: 306 NAPI_GRO_CB(skb)->flush |= flush; 307 return pp; 308 } 309 EXPORT_SYMBOL(udp_gro_receive); 310 311 static struct sk_buff **udp4_gro_receive(struct sk_buff **head, 312 struct sk_buff *skb) 313 { 314 struct udphdr *uh = udp_gro_udphdr(skb); 315 316 if (unlikely(!uh)) 317 goto flush; 318 319 /* Don't bother verifying checksum if we're going to flush anyway. */ 320 if (NAPI_GRO_CB(skb)->flush) 321 goto skip; 322 323 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 324 inet_gro_compute_pseudo)) 325 goto flush; 326 else if (uh->check) 327 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 328 inet_gro_compute_pseudo); 329 skip: 330 NAPI_GRO_CB(skb)->is_ipv6 = 0; 331 return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb); 332 333 flush: 334 NAPI_GRO_CB(skb)->flush = 1; 335 return NULL; 336 } 337 338 int udp_gro_complete(struct sk_buff *skb, int nhoff, 339 udp_lookup_t lookup) 340 { 341 __be16 newlen = htons(skb->len - nhoff); 342 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 343 int err = -ENOSYS; 344 struct sock *sk; 345 346 uh->len = newlen; 347 348 /* Set encapsulation before calling into inner gro_complete() functions 349 * to make them set up the inner offsets. 350 */ 351 skb->encapsulation = 1; 352 353 rcu_read_lock(); 354 sk = (*lookup)(skb, uh->source, uh->dest); 355 if (sk && udp_sk(sk)->gro_complete) 356 err = udp_sk(sk)->gro_complete(sk, skb, 357 nhoff + sizeof(struct udphdr)); 358 rcu_read_unlock(); 359 360 if (skb->remcsum_offload) 361 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM; 362 363 return err; 364 } 365 EXPORT_SYMBOL(udp_gro_complete); 366 367 static int udp4_gro_complete(struct sk_buff *skb, int nhoff) 368 { 369 const struct iphdr *iph = ip_hdr(skb); 370 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 371 372 if (uh->check) { 373 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM; 374 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr, 375 iph->daddr, 0); 376 } else { 377 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL; 378 } 379 380 return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb); 381 } 382 383 static const struct net_offload udpv4_offload = { 384 .callbacks = { 385 .gso_segment = udp4_ufo_fragment, 386 .gro_receive = udp4_gro_receive, 387 .gro_complete = udp4_gro_complete, 388 }, 389 }; 390 391 int __init udpv4_offload_init(void) 392 { 393 return inet_add_offload(&udpv4_offload, IPPROTO_UDP); 394 } 395