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 * TCPv4 GSO/GRO support 11 */ 12 13 #include <linux/skbuff.h> 14 #include <net/tcp.h> 15 #include <net/protocol.h> 16 17 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 18 netdev_features_t features) 19 { 20 struct sk_buff *segs = ERR_PTR(-EINVAL); 21 unsigned int sum_truesize = 0; 22 struct tcphdr *th; 23 unsigned int thlen; 24 unsigned int seq; 25 __be32 delta; 26 unsigned int oldlen; 27 unsigned int mss; 28 struct sk_buff *gso_skb = skb; 29 __sum16 newcheck; 30 bool ooo_okay, copy_destructor; 31 32 if (!pskb_may_pull(skb, sizeof(*th))) 33 goto out; 34 35 th = tcp_hdr(skb); 36 thlen = th->doff * 4; 37 if (thlen < sizeof(*th)) 38 goto out; 39 40 if (!pskb_may_pull(skb, thlen)) 41 goto out; 42 43 oldlen = (u16)~skb->len; 44 __skb_pull(skb, thlen); 45 46 mss = tcp_skb_mss(skb); 47 if (unlikely(skb->len <= mss)) 48 goto out; 49 50 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 51 /* Packet is from an untrusted source, reset gso_segs. */ 52 int type = skb_shinfo(skb)->gso_type; 53 54 if (unlikely(type & 55 ~(SKB_GSO_TCPV4 | 56 SKB_GSO_DODGY | 57 SKB_GSO_TCP_ECN | 58 SKB_GSO_TCPV6 | 59 SKB_GSO_GRE | 60 SKB_GSO_IPIP | 61 SKB_GSO_SIT | 62 SKB_GSO_MPLS | 63 SKB_GSO_UDP_TUNNEL | 64 0) || 65 !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))) 66 goto out; 67 68 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 69 70 segs = NULL; 71 goto out; 72 } 73 74 copy_destructor = gso_skb->destructor == tcp_wfree; 75 ooo_okay = gso_skb->ooo_okay; 76 /* All segments but the first should have ooo_okay cleared */ 77 skb->ooo_okay = 0; 78 79 segs = skb_segment(skb, features); 80 if (IS_ERR(segs)) 81 goto out; 82 83 /* Only first segment might have ooo_okay set */ 84 segs->ooo_okay = ooo_okay; 85 86 delta = htonl(oldlen + (thlen + mss)); 87 88 skb = segs; 89 th = tcp_hdr(skb); 90 seq = ntohl(th->seq); 91 92 newcheck = ~csum_fold((__force __wsum)((__force u32)th->check + 93 (__force u32)delta)); 94 95 do { 96 th->fin = th->psh = 0; 97 th->check = newcheck; 98 99 if (skb->ip_summed != CHECKSUM_PARTIAL) 100 th->check = 101 csum_fold(csum_partial(skb_transport_header(skb), 102 thlen, skb->csum)); 103 104 seq += mss; 105 if (copy_destructor) { 106 skb->destructor = gso_skb->destructor; 107 skb->sk = gso_skb->sk; 108 sum_truesize += skb->truesize; 109 } 110 skb = skb->next; 111 th = tcp_hdr(skb); 112 113 th->seq = htonl(seq); 114 th->cwr = 0; 115 } while (skb->next); 116 117 /* Following permits TCP Small Queues to work well with GSO : 118 * The callback to TCP stack will be called at the time last frag 119 * is freed at TX completion, and not right now when gso_skb 120 * is freed by GSO engine 121 */ 122 if (copy_destructor) { 123 swap(gso_skb->sk, skb->sk); 124 swap(gso_skb->destructor, skb->destructor); 125 sum_truesize += skb->truesize; 126 atomic_add(sum_truesize - gso_skb->truesize, 127 &skb->sk->sk_wmem_alloc); 128 } 129 130 delta = htonl(oldlen + (skb_tail_pointer(skb) - 131 skb_transport_header(skb)) + 132 skb->data_len); 133 th->check = ~csum_fold((__force __wsum)((__force u32)th->check + 134 (__force u32)delta)); 135 if (skb->ip_summed != CHECKSUM_PARTIAL) 136 th->check = csum_fold(csum_partial(skb_transport_header(skb), 137 thlen, skb->csum)); 138 out: 139 return segs; 140 } 141 142 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb) 143 { 144 struct sk_buff **pp = NULL; 145 struct sk_buff *p; 146 struct tcphdr *th; 147 struct tcphdr *th2; 148 unsigned int len; 149 unsigned int thlen; 150 __be32 flags; 151 unsigned int mss = 1; 152 unsigned int hlen; 153 unsigned int off; 154 int flush = 1; 155 int i; 156 157 off = skb_gro_offset(skb); 158 hlen = off + sizeof(*th); 159 th = skb_gro_header_fast(skb, off); 160 if (skb_gro_header_hard(skb, hlen)) { 161 th = skb_gro_header_slow(skb, hlen, off); 162 if (unlikely(!th)) 163 goto out; 164 } 165 166 thlen = th->doff * 4; 167 if (thlen < sizeof(*th)) 168 goto out; 169 170 hlen = off + thlen; 171 if (skb_gro_header_hard(skb, hlen)) { 172 th = skb_gro_header_slow(skb, hlen, off); 173 if (unlikely(!th)) 174 goto out; 175 } 176 177 skb_gro_pull(skb, thlen); 178 179 len = skb_gro_len(skb); 180 flags = tcp_flag_word(th); 181 182 for (; (p = *head); head = &p->next) { 183 if (!NAPI_GRO_CB(p)->same_flow) 184 continue; 185 186 th2 = tcp_hdr(p); 187 188 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 189 NAPI_GRO_CB(p)->same_flow = 0; 190 continue; 191 } 192 193 goto found; 194 } 195 196 goto out_check_final; 197 198 found: 199 /* Include the IP ID check below from the inner most IP hdr */ 200 flush = NAPI_GRO_CB(p)->flush | NAPI_GRO_CB(p)->flush_id; 201 flush |= (__force int)(flags & TCP_FLAG_CWR); 202 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 203 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 204 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 205 for (i = sizeof(*th); i < thlen; i += 4) 206 flush |= *(u32 *)((u8 *)th + i) ^ 207 *(u32 *)((u8 *)th2 + i); 208 209 mss = tcp_skb_mss(p); 210 211 flush |= (len - 1) >= mss; 212 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 213 214 if (flush || skb_gro_receive(head, skb)) { 215 mss = 1; 216 goto out_check_final; 217 } 218 219 p = *head; 220 th2 = tcp_hdr(p); 221 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 222 223 out_check_final: 224 flush = len < mss; 225 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 226 TCP_FLAG_RST | TCP_FLAG_SYN | 227 TCP_FLAG_FIN)); 228 229 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 230 pp = head; 231 232 out: 233 NAPI_GRO_CB(skb)->flush |= (flush != 0); 234 235 return pp; 236 } 237 238 int tcp_gro_complete(struct sk_buff *skb) 239 { 240 struct tcphdr *th = tcp_hdr(skb); 241 242 skb->csum_start = (unsigned char *)th - skb->head; 243 skb->csum_offset = offsetof(struct tcphdr, check); 244 skb->ip_summed = CHECKSUM_PARTIAL; 245 246 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 247 248 if (th->cwr) 249 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 250 251 return 0; 252 } 253 EXPORT_SYMBOL(tcp_gro_complete); 254 255 static int tcp_v4_gso_send_check(struct sk_buff *skb) 256 { 257 const struct iphdr *iph; 258 struct tcphdr *th; 259 260 if (!pskb_may_pull(skb, sizeof(*th))) 261 return -EINVAL; 262 263 iph = ip_hdr(skb); 264 th = tcp_hdr(skb); 265 266 th->check = 0; 267 skb->ip_summed = CHECKSUM_PARTIAL; 268 __tcp_v4_send_check(skb, iph->saddr, iph->daddr); 269 return 0; 270 } 271 272 static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb) 273 { 274 /* Use the IP hdr immediately proceeding for this transport */ 275 const struct iphdr *iph = skb_gro_network_header(skb); 276 __wsum wsum; 277 278 /* Don't bother verifying checksum if we're going to flush anyway. */ 279 if (NAPI_GRO_CB(skb)->flush) 280 goto skip_csum; 281 282 wsum = NAPI_GRO_CB(skb)->csum; 283 284 switch (skb->ip_summed) { 285 case CHECKSUM_NONE: 286 wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 287 0); 288 289 /* fall through */ 290 291 case CHECKSUM_COMPLETE: 292 if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr, 293 wsum)) { 294 skb->ip_summed = CHECKSUM_UNNECESSARY; 295 break; 296 } 297 298 NAPI_GRO_CB(skb)->flush = 1; 299 return NULL; 300 } 301 302 skip_csum: 303 return tcp_gro_receive(head, skb); 304 } 305 306 static int tcp4_gro_complete(struct sk_buff *skb, int thoff) 307 { 308 const struct iphdr *iph = ip_hdr(skb); 309 struct tcphdr *th = tcp_hdr(skb); 310 311 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, 312 iph->daddr, 0); 313 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4; 314 315 return tcp_gro_complete(skb); 316 } 317 318 static const struct net_offload tcpv4_offload = { 319 .callbacks = { 320 .gso_send_check = tcp_v4_gso_send_check, 321 .gso_segment = tcp_gso_segment, 322 .gro_receive = tcp4_gro_receive, 323 .gro_complete = tcp4_gro_complete, 324 }, 325 }; 326 327 int __init tcpv4_offload_init(void) 328 { 329 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 330 } 331