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 33 if (unlikely(!pskb_may_pull(skb, tnl_hlen))) 34 goto out; 35 36 /* Adjust partial header checksum to negate old length. 37 * We cannot rely on the value contained in uh->len as it is 38 * possible that the actual value exceeds the boundaries of the 39 * 16 bit length field due to the header being added outside of an 40 * IP or IPv6 frame that was already limited to 64K - 1. 41 */ 42 if (skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL) 43 partial = (__force __wsum)uh->len; 44 else 45 partial = (__force __wsum)htonl(skb->len); 46 partial = csum_sub(csum_unfold(uh->check), partial); 47 48 /* setup inner skb. */ 49 skb->encapsulation = 0; 50 SKB_GSO_CB(skb)->encap_level = 0; 51 __skb_pull(skb, tnl_hlen); 52 skb_reset_mac_header(skb); 53 skb_set_network_header(skb, skb_inner_network_offset(skb)); 54 skb->mac_len = skb_inner_network_offset(skb); 55 skb->protocol = new_protocol; 56 57 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM); 58 skb->encap_hdr_csum = need_csum; 59 60 remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM); 61 skb->remcsum_offload = remcsum; 62 63 ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP); 64 65 /* Try to offload checksum if possible */ 66 offload_csum = !!(need_csum && 67 (skb->dev->features & 68 (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) : 69 (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM)))); 70 71 features &= skb->dev->hw_enc_features; 72 73 /* The only checksum offload we care about from here on out is the 74 * outer one so strip the existing checksum feature flags and 75 * instead set the flag based on our outer checksum offload value. 76 */ 77 if (remcsum || ufo) { 78 features &= ~NETIF_F_CSUM_MASK; 79 if (!need_csum || offload_csum) 80 features |= NETIF_F_HW_CSUM; 81 } 82 83 /* segment inner packet. */ 84 segs = gso_inner_segment(skb, features); 85 if (IS_ERR_OR_NULL(segs)) { 86 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset, 87 mac_len); 88 goto out; 89 } 90 91 gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL); 92 93 outer_hlen = skb_tnl_header_len(skb); 94 udp_offset = outer_hlen - tnl_hlen; 95 skb = segs; 96 do { 97 unsigned int len; 98 99 if (remcsum) 100 skb->ip_summed = CHECKSUM_NONE; 101 102 /* Set up inner headers if we are offloading inner checksum */ 103 if (skb->ip_summed == CHECKSUM_PARTIAL) { 104 skb_reset_inner_headers(skb); 105 skb->encapsulation = 1; 106 } 107 108 skb->mac_len = mac_len; 109 skb->protocol = protocol; 110 111 __skb_push(skb, outer_hlen); 112 skb_reset_mac_header(skb); 113 skb_set_network_header(skb, mac_len); 114 skb_set_transport_header(skb, udp_offset); 115 len = skb->len - udp_offset; 116 uh = udp_hdr(skb); 117 118 /* If we are only performing partial GSO the inner header 119 * will be using a length value equal to only one MSS sized 120 * segment instead of the entire frame. 121 */ 122 if (gso_partial) { 123 uh->len = htons(skb_shinfo(skb)->gso_size + 124 SKB_GSO_CB(skb)->data_offset + 125 skb->head - (unsigned char *)uh); 126 } else { 127 uh->len = htons(len); 128 } 129 130 if (!need_csum) 131 continue; 132 133 uh->check = ~csum_fold(csum_add(partial, 134 (__force __wsum)htonl(len))); 135 136 if (skb->encapsulation || !offload_csum) { 137 uh->check = gso_make_checksum(skb, ~uh->check); 138 if (uh->check == 0) 139 uh->check = CSUM_MANGLED_0; 140 } else { 141 skb->ip_summed = CHECKSUM_PARTIAL; 142 skb->csum_start = skb_transport_header(skb) - skb->head; 143 skb->csum_offset = offsetof(struct udphdr, check); 144 } 145 } while ((skb = skb->next)); 146 out: 147 return segs; 148 } 149 150 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb, 151 netdev_features_t features, 152 bool is_ipv6) 153 { 154 __be16 protocol = skb->protocol; 155 const struct net_offload **offloads; 156 const struct net_offload *ops; 157 struct sk_buff *segs = ERR_PTR(-EINVAL); 158 struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb, 159 netdev_features_t features); 160 161 rcu_read_lock(); 162 163 switch (skb->inner_protocol_type) { 164 case ENCAP_TYPE_ETHER: 165 protocol = skb->inner_protocol; 166 gso_inner_segment = skb_mac_gso_segment; 167 break; 168 case ENCAP_TYPE_IPPROTO: 169 offloads = is_ipv6 ? inet6_offloads : inet_offloads; 170 ops = rcu_dereference(offloads[skb->inner_ipproto]); 171 if (!ops || !ops->callbacks.gso_segment) 172 goto out_unlock; 173 gso_inner_segment = ops->callbacks.gso_segment; 174 break; 175 default: 176 goto out_unlock; 177 } 178 179 segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment, 180 protocol, is_ipv6); 181 182 out_unlock: 183 rcu_read_unlock(); 184 185 return segs; 186 } 187 EXPORT_SYMBOL(skb_udp_tunnel_segment); 188 189 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, 190 netdev_features_t features) 191 { 192 struct sk_buff *segs = ERR_PTR(-EINVAL); 193 unsigned int mss; 194 __wsum csum; 195 struct udphdr *uh; 196 struct iphdr *iph; 197 198 if (skb->encapsulation && 199 (skb_shinfo(skb)->gso_type & 200 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) { 201 segs = skb_udp_tunnel_segment(skb, features, false); 202 goto out; 203 } 204 205 if (!pskb_may_pull(skb, sizeof(struct udphdr))) 206 goto out; 207 208 mss = skb_shinfo(skb)->gso_size; 209 if (unlikely(skb->len <= mss)) 210 goto out; 211 212 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 213 /* Packet is from an untrusted source, reset gso_segs. */ 214 215 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 216 217 segs = NULL; 218 goto out; 219 } 220 221 /* Do software UFO. Complete and fill in the UDP checksum as 222 * HW cannot do checksum of UDP packets sent as multiple 223 * IP fragments. 224 */ 225 226 uh = udp_hdr(skb); 227 iph = ip_hdr(skb); 228 229 uh->check = 0; 230 csum = skb_checksum(skb, 0, skb->len, 0); 231 uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum); 232 if (uh->check == 0) 233 uh->check = CSUM_MANGLED_0; 234 235 skb->ip_summed = CHECKSUM_NONE; 236 237 /* If there is no outer header we can fake a checksum offload 238 * due to the fact that we have already done the checksum in 239 * software prior to segmenting the frame. 240 */ 241 if (!skb->encap_hdr_csum) 242 features |= NETIF_F_HW_CSUM; 243 244 /* Fragment the skb. IP headers of the fragments are updated in 245 * inet_gso_segment() 246 */ 247 segs = skb_segment(skb, features); 248 out: 249 return segs; 250 } 251 252 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb, 253 struct udphdr *uh, udp_lookup_t lookup) 254 { 255 struct sk_buff *p, **pp = NULL; 256 struct udphdr *uh2; 257 unsigned int off = skb_gro_offset(skb); 258 int flush = 1; 259 struct sock *sk; 260 261 if (NAPI_GRO_CB(skb)->encap_mark || 262 (skb->ip_summed != CHECKSUM_PARTIAL && 263 NAPI_GRO_CB(skb)->csum_cnt == 0 && 264 !NAPI_GRO_CB(skb)->csum_valid)) 265 goto out; 266 267 /* mark that this skb passed once through the tunnel gro layer */ 268 NAPI_GRO_CB(skb)->encap_mark = 1; 269 270 rcu_read_lock(); 271 sk = (*lookup)(skb, uh->source, uh->dest); 272 273 if (sk && udp_sk(sk)->gro_receive) 274 goto unflush; 275 goto out_unlock; 276 277 unflush: 278 flush = 0; 279 280 for (p = *head; p; p = p->next) { 281 if (!NAPI_GRO_CB(p)->same_flow) 282 continue; 283 284 uh2 = (struct udphdr *)(p->data + off); 285 286 /* Match ports and either checksums are either both zero 287 * or nonzero. 288 */ 289 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) || 290 (!uh->check ^ !uh2->check)) { 291 NAPI_GRO_CB(p)->same_flow = 0; 292 continue; 293 } 294 } 295 296 skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */ 297 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); 298 pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb); 299 300 out_unlock: 301 rcu_read_unlock(); 302 out: 303 NAPI_GRO_CB(skb)->flush |= flush; 304 return pp; 305 } 306 EXPORT_SYMBOL(udp_gro_receive); 307 308 static struct sk_buff **udp4_gro_receive(struct sk_buff **head, 309 struct sk_buff *skb) 310 { 311 struct udphdr *uh = udp_gro_udphdr(skb); 312 313 if (unlikely(!uh)) 314 goto flush; 315 316 /* Don't bother verifying checksum if we're going to flush anyway. */ 317 if (NAPI_GRO_CB(skb)->flush) 318 goto skip; 319 320 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 321 inet_gro_compute_pseudo)) 322 goto flush; 323 else if (uh->check) 324 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 325 inet_gro_compute_pseudo); 326 skip: 327 NAPI_GRO_CB(skb)->is_ipv6 = 0; 328 return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb); 329 330 flush: 331 NAPI_GRO_CB(skb)->flush = 1; 332 return NULL; 333 } 334 335 int udp_gro_complete(struct sk_buff *skb, int nhoff, 336 udp_lookup_t lookup) 337 { 338 __be16 newlen = htons(skb->len - nhoff); 339 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 340 int err = -ENOSYS; 341 struct sock *sk; 342 343 uh->len = newlen; 344 345 /* Set encapsulation before calling into inner gro_complete() functions 346 * to make them set up the inner offsets. 347 */ 348 skb->encapsulation = 1; 349 350 rcu_read_lock(); 351 sk = (*lookup)(skb, uh->source, uh->dest); 352 if (sk && udp_sk(sk)->gro_complete) 353 err = udp_sk(sk)->gro_complete(sk, skb, 354 nhoff + sizeof(struct udphdr)); 355 rcu_read_unlock(); 356 357 if (skb->remcsum_offload) 358 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM; 359 360 return err; 361 } 362 EXPORT_SYMBOL(udp_gro_complete); 363 364 static int udp4_gro_complete(struct sk_buff *skb, int nhoff) 365 { 366 const struct iphdr *iph = ip_hdr(skb); 367 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 368 369 if (uh->check) { 370 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM; 371 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr, 372 iph->daddr, 0); 373 } else { 374 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL; 375 } 376 377 return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb); 378 } 379 380 static const struct net_offload udpv4_offload = { 381 .callbacks = { 382 .gso_segment = udp4_ufo_fragment, 383 .gro_receive = udp4_gro_receive, 384 .gro_complete = udp4_gro_complete, 385 }, 386 }; 387 388 int __init udpv4_offload_init(void) 389 { 390 return inet_add_offload(&udpv4_offload, IPPROTO_UDP); 391 } 392