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_GRE_CSUM | 61 SKB_GSO_IPIP | 62 SKB_GSO_SIT | 63 SKB_GSO_MPLS | 64 SKB_GSO_UDP_TUNNEL | 65 SKB_GSO_UDP_TUNNEL_CSUM | 66 0) || 67 !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))) 68 goto out; 69 70 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 71 72 segs = NULL; 73 goto out; 74 } 75 76 copy_destructor = gso_skb->destructor == tcp_wfree; 77 ooo_okay = gso_skb->ooo_okay; 78 /* All segments but the first should have ooo_okay cleared */ 79 skb->ooo_okay = 0; 80 81 segs = skb_segment(skb, features); 82 if (IS_ERR(segs)) 83 goto out; 84 85 /* Only first segment might have ooo_okay set */ 86 segs->ooo_okay = ooo_okay; 87 88 delta = htonl(oldlen + (thlen + mss)); 89 90 skb = segs; 91 th = tcp_hdr(skb); 92 seq = ntohl(th->seq); 93 94 newcheck = ~csum_fold((__force __wsum)((__force u32)th->check + 95 (__force u32)delta)); 96 97 do { 98 th->fin = th->psh = 0; 99 th->check = newcheck; 100 101 if (skb->ip_summed != CHECKSUM_PARTIAL) 102 th->check = gso_make_checksum(skb, ~th->check); 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 = gso_make_checksum(skb, ~th->check); 137 out: 138 return segs; 139 } 140 141 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb) 142 { 143 struct sk_buff **pp = NULL; 144 struct sk_buff *p; 145 struct tcphdr *th; 146 struct tcphdr *th2; 147 unsigned int len; 148 unsigned int thlen; 149 __be32 flags; 150 unsigned int mss = 1; 151 unsigned int hlen; 152 unsigned int off; 153 int flush = 1; 154 int i; 155 156 off = skb_gro_offset(skb); 157 hlen = off + sizeof(*th); 158 th = skb_gro_header_fast(skb, off); 159 if (skb_gro_header_hard(skb, hlen)) { 160 th = skb_gro_header_slow(skb, hlen, off); 161 if (unlikely(!th)) 162 goto out; 163 } 164 165 thlen = th->doff * 4; 166 if (thlen < sizeof(*th)) 167 goto out; 168 169 hlen = off + thlen; 170 if (skb_gro_header_hard(skb, hlen)) { 171 th = skb_gro_header_slow(skb, hlen, off); 172 if (unlikely(!th)) 173 goto out; 174 } 175 176 skb_gro_pull(skb, thlen); 177 178 len = skb_gro_len(skb); 179 flags = tcp_flag_word(th); 180 181 for (; (p = *head); head = &p->next) { 182 if (!NAPI_GRO_CB(p)->same_flow) 183 continue; 184 185 th2 = tcp_hdr(p); 186 187 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 188 NAPI_GRO_CB(p)->same_flow = 0; 189 continue; 190 } 191 192 goto found; 193 } 194 195 goto out_check_final; 196 197 found: 198 /* Include the IP ID check below from the inner most IP hdr */ 199 flush = NAPI_GRO_CB(p)->flush | NAPI_GRO_CB(p)->flush_id; 200 flush |= (__force int)(flags & TCP_FLAG_CWR); 201 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 202 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 203 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 204 for (i = sizeof(*th); i < thlen; i += 4) 205 flush |= *(u32 *)((u8 *)th + i) ^ 206 *(u32 *)((u8 *)th2 + i); 207 208 mss = tcp_skb_mss(p); 209 210 flush |= (len - 1) >= mss; 211 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 212 213 if (flush || skb_gro_receive(head, skb)) { 214 mss = 1; 215 goto out_check_final; 216 } 217 218 p = *head; 219 th2 = tcp_hdr(p); 220 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 221 222 out_check_final: 223 flush = len < mss; 224 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 225 TCP_FLAG_RST | TCP_FLAG_SYN | 226 TCP_FLAG_FIN)); 227 228 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 229 pp = head; 230 231 out: 232 NAPI_GRO_CB(skb)->flush |= (flush != 0); 233 234 return pp; 235 } 236 237 int tcp_gro_complete(struct sk_buff *skb) 238 { 239 struct tcphdr *th = tcp_hdr(skb); 240 241 skb->csum_start = (unsigned char *)th - skb->head; 242 skb->csum_offset = offsetof(struct tcphdr, check); 243 skb->ip_summed = CHECKSUM_PARTIAL; 244 245 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 246 247 if (th->cwr) 248 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 249 250 return 0; 251 } 252 EXPORT_SYMBOL(tcp_gro_complete); 253 254 static int tcp_v4_gso_send_check(struct sk_buff *skb) 255 { 256 const struct iphdr *iph; 257 struct tcphdr *th; 258 259 if (!pskb_may_pull(skb, sizeof(*th))) 260 return -EINVAL; 261 262 iph = ip_hdr(skb); 263 th = tcp_hdr(skb); 264 265 th->check = 0; 266 skb->ip_summed = CHECKSUM_PARTIAL; 267 __tcp_v4_send_check(skb, iph->saddr, iph->daddr); 268 return 0; 269 } 270 271 static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb) 272 { 273 /* Use the IP hdr immediately proceeding for this transport */ 274 const struct iphdr *iph = skb_gro_network_header(skb); 275 __wsum wsum; 276 277 /* Don't bother verifying checksum if we're going to flush anyway. */ 278 if (NAPI_GRO_CB(skb)->flush) 279 goto skip_csum; 280 281 wsum = NAPI_GRO_CB(skb)->csum; 282 283 switch (skb->ip_summed) { 284 case CHECKSUM_NONE: 285 wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 286 0); 287 288 /* fall through */ 289 290 case CHECKSUM_COMPLETE: 291 if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr, 292 wsum)) { 293 skb->ip_summed = CHECKSUM_UNNECESSARY; 294 break; 295 } 296 297 NAPI_GRO_CB(skb)->flush = 1; 298 return NULL; 299 } 300 301 skip_csum: 302 return tcp_gro_receive(head, skb); 303 } 304 305 static int tcp4_gro_complete(struct sk_buff *skb, int thoff) 306 { 307 const struct iphdr *iph = ip_hdr(skb); 308 struct tcphdr *th = tcp_hdr(skb); 309 310 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, 311 iph->daddr, 0); 312 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4; 313 314 return tcp_gro_complete(skb); 315 } 316 317 static const struct net_offload tcpv4_offload = { 318 .callbacks = { 319 .gso_send_check = tcp_v4_gso_send_check, 320 .gso_segment = tcp_gso_segment, 321 .gro_receive = tcp4_gro_receive, 322 .gro_complete = tcp4_gro_complete, 323 }, 324 }; 325 326 int __init tcpv4_offload_init(void) 327 { 328 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 329 } 330