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