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_tso_segment(struct sk_buff *skb, 18 netdev_features_t features) 19 { 20 struct sk_buff *segs = ERR_PTR(-EINVAL); 21 struct tcphdr *th; 22 unsigned int thlen; 23 unsigned int seq; 24 __be32 delta; 25 unsigned int oldlen; 26 unsigned int mss; 27 struct sk_buff *gso_skb = skb; 28 __sum16 newcheck; 29 bool ooo_okay, copy_destructor; 30 31 if (!pskb_may_pull(skb, sizeof(*th))) 32 goto out; 33 34 th = tcp_hdr(skb); 35 thlen = th->doff * 4; 36 if (thlen < sizeof(*th)) 37 goto out; 38 39 if (!pskb_may_pull(skb, thlen)) 40 goto out; 41 42 oldlen = (u16)~skb->len; 43 __skb_pull(skb, thlen); 44 45 mss = tcp_skb_mss(skb); 46 if (unlikely(skb->len <= mss)) 47 goto out; 48 49 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 50 /* Packet is from an untrusted source, reset gso_segs. */ 51 int type = skb_shinfo(skb)->gso_type; 52 53 if (unlikely(type & 54 ~(SKB_GSO_TCPV4 | 55 SKB_GSO_DODGY | 56 SKB_GSO_TCP_ECN | 57 SKB_GSO_TCPV6 | 58 SKB_GSO_GRE | 59 SKB_GSO_MPLS | 60 SKB_GSO_UDP_TUNNEL | 61 0) || 62 !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))) 63 goto out; 64 65 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 66 67 segs = NULL; 68 goto out; 69 } 70 71 copy_destructor = gso_skb->destructor == tcp_wfree; 72 ooo_okay = gso_skb->ooo_okay; 73 /* All segments but the first should have ooo_okay cleared */ 74 skb->ooo_okay = 0; 75 76 segs = skb_segment(skb, features); 77 if (IS_ERR(segs)) 78 goto out; 79 80 /* Only first segment might have ooo_okay set */ 81 segs->ooo_okay = ooo_okay; 82 83 delta = htonl(oldlen + (thlen + mss)); 84 85 skb = segs; 86 th = tcp_hdr(skb); 87 seq = ntohl(th->seq); 88 89 newcheck = ~csum_fold((__force __wsum)((__force u32)th->check + 90 (__force u32)delta)); 91 92 do { 93 th->fin = th->psh = 0; 94 th->check = newcheck; 95 96 if (skb->ip_summed != CHECKSUM_PARTIAL) 97 th->check = 98 csum_fold(csum_partial(skb_transport_header(skb), 99 thlen, skb->csum)); 100 101 seq += mss; 102 if (copy_destructor) { 103 skb->destructor = gso_skb->destructor; 104 skb->sk = gso_skb->sk; 105 /* {tcp|sock}_wfree() use exact truesize accounting : 106 * sum(skb->truesize) MUST be exactly be gso_skb->truesize 107 * So we account mss bytes of 'true size' for each segment. 108 * The last segment will contain the remaining. 109 */ 110 skb->truesize = mss; 111 gso_skb->truesize -= mss; 112 } 113 skb = skb->next; 114 th = tcp_hdr(skb); 115 116 th->seq = htonl(seq); 117 th->cwr = 0; 118 } while (skb->next); 119 120 /* Following permits TCP Small Queues to work well with GSO : 121 * The callback to TCP stack will be called at the time last frag 122 * is freed at TX completion, and not right now when gso_skb 123 * is freed by GSO engine 124 */ 125 if (copy_destructor) { 126 swap(gso_skb->sk, skb->sk); 127 swap(gso_skb->destructor, skb->destructor); 128 swap(gso_skb->truesize, skb->truesize); 129 } 130 131 delta = htonl(oldlen + (skb_tail_pointer(skb) - 132 skb_transport_header(skb)) + 133 skb->data_len); 134 th->check = ~csum_fold((__force __wsum)((__force u32)th->check + 135 (__force u32)delta)); 136 if (skb->ip_summed != CHECKSUM_PARTIAL) 137 th->check = csum_fold(csum_partial(skb_transport_header(skb), 138 thlen, skb->csum)); 139 out: 140 return segs; 141 } 142 EXPORT_SYMBOL(tcp_tso_segment); 143 144 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb) 145 { 146 struct sk_buff **pp = NULL; 147 struct sk_buff *p; 148 struct tcphdr *th; 149 struct tcphdr *th2; 150 unsigned int len; 151 unsigned int thlen; 152 __be32 flags; 153 unsigned int mss = 1; 154 unsigned int hlen; 155 unsigned int off; 156 int flush = 1; 157 int i; 158 159 off = skb_gro_offset(skb); 160 hlen = off + sizeof(*th); 161 th = skb_gro_header_fast(skb, off); 162 if (skb_gro_header_hard(skb, hlen)) { 163 th = skb_gro_header_slow(skb, hlen, off); 164 if (unlikely(!th)) 165 goto out; 166 } 167 168 thlen = th->doff * 4; 169 if (thlen < sizeof(*th)) 170 goto out; 171 172 hlen = off + thlen; 173 if (skb_gro_header_hard(skb, hlen)) { 174 th = skb_gro_header_slow(skb, hlen, off); 175 if (unlikely(!th)) 176 goto out; 177 } 178 179 skb_gro_pull(skb, thlen); 180 181 len = skb_gro_len(skb); 182 flags = tcp_flag_word(th); 183 184 for (; (p = *head); head = &p->next) { 185 if (!NAPI_GRO_CB(p)->same_flow) 186 continue; 187 188 th2 = tcp_hdr(p); 189 190 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 191 NAPI_GRO_CB(p)->same_flow = 0; 192 continue; 193 } 194 195 goto found; 196 } 197 198 goto out_check_final; 199 200 found: 201 flush = NAPI_GRO_CB(p)->flush; 202 flush |= (__force int)(flags & TCP_FLAG_CWR); 203 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 204 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 205 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 206 for (i = sizeof(*th); i < thlen; i += 4) 207 flush |= *(u32 *)((u8 *)th + i) ^ 208 *(u32 *)((u8 *)th2 + i); 209 210 mss = tcp_skb_mss(p); 211 212 flush |= (len - 1) >= mss; 213 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 214 215 if (flush || skb_gro_receive(head, skb)) { 216 mss = 1; 217 goto out_check_final; 218 } 219 220 p = *head; 221 th2 = tcp_hdr(p); 222 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 223 224 out_check_final: 225 flush = len < mss; 226 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 227 TCP_FLAG_RST | TCP_FLAG_SYN | 228 TCP_FLAG_FIN)); 229 230 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 231 pp = head; 232 233 out: 234 NAPI_GRO_CB(skb)->flush |= flush; 235 236 return pp; 237 } 238 EXPORT_SYMBOL(tcp_gro_receive); 239 240 int tcp_gro_complete(struct sk_buff *skb) 241 { 242 struct tcphdr *th = tcp_hdr(skb); 243 244 skb->csum_start = skb_transport_header(skb) - skb->head; 245 skb->csum_offset = offsetof(struct tcphdr, check); 246 skb->ip_summed = CHECKSUM_PARTIAL; 247 248 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 249 250 if (th->cwr) 251 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 252 253 return 0; 254 } 255 EXPORT_SYMBOL(tcp_gro_complete); 256 257 static int tcp_v4_gso_send_check(struct sk_buff *skb) 258 { 259 const struct iphdr *iph; 260 struct tcphdr *th; 261 262 if (!pskb_may_pull(skb, sizeof(*th))) 263 return -EINVAL; 264 265 iph = ip_hdr(skb); 266 th = tcp_hdr(skb); 267 268 th->check = 0; 269 skb->ip_summed = CHECKSUM_PARTIAL; 270 __tcp_v4_send_check(skb, iph->saddr, iph->daddr); 271 return 0; 272 } 273 274 static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb) 275 { 276 const struct iphdr *iph = skb_gro_network_header(skb); 277 __wsum wsum; 278 __sum16 sum; 279 280 switch (skb->ip_summed) { 281 case CHECKSUM_COMPLETE: 282 if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr, 283 skb->csum)) { 284 skb->ip_summed = CHECKSUM_UNNECESSARY; 285 break; 286 } 287 flush: 288 NAPI_GRO_CB(skb)->flush = 1; 289 return NULL; 290 291 case CHECKSUM_NONE: 292 wsum = csum_tcpudp_nofold(iph->saddr, iph->daddr, 293 skb_gro_len(skb), IPPROTO_TCP, 0); 294 sum = csum_fold(skb_checksum(skb, 295 skb_gro_offset(skb), 296 skb_gro_len(skb), 297 wsum)); 298 if (sum) 299 goto flush; 300 301 skb->ip_summed = CHECKSUM_UNNECESSARY; 302 break; 303 } 304 305 return tcp_gro_receive(head, skb); 306 } 307 308 static int tcp4_gro_complete(struct sk_buff *skb) 309 { 310 const struct iphdr *iph = ip_hdr(skb); 311 struct tcphdr *th = tcp_hdr(skb); 312 313 th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb), 314 iph->saddr, iph->daddr, 0); 315 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4; 316 317 return tcp_gro_complete(skb); 318 } 319 320 static const struct net_offload tcpv4_offload = { 321 .callbacks = { 322 .gso_send_check = tcp_v4_gso_send_check, 323 .gso_segment = tcp_tso_segment, 324 .gro_receive = tcp4_gro_receive, 325 .gro_complete = tcp4_gro_complete, 326 }, 327 }; 328 329 int __init tcpv4_offload_init(void) 330 { 331 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 332 } 333