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 static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq, 18 unsigned int seq, unsigned int mss) 19 { 20 while (skb) { 21 if (before(ts_seq, seq + mss)) { 22 skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP; 23 skb_shinfo(skb)->tskey = ts_seq; 24 return; 25 } 26 27 skb = skb->next; 28 seq += mss; 29 } 30 } 31 32 struct sk_buff *tcp4_gso_segment(struct sk_buff *skb, 33 netdev_features_t features) 34 { 35 if (!pskb_may_pull(skb, sizeof(struct tcphdr))) 36 return ERR_PTR(-EINVAL); 37 38 if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) { 39 const struct iphdr *iph = ip_hdr(skb); 40 struct tcphdr *th = tcp_hdr(skb); 41 42 /* Set up checksum pseudo header, usually expect stack to 43 * have done this already. 44 */ 45 46 th->check = 0; 47 skb->ip_summed = CHECKSUM_PARTIAL; 48 __tcp_v4_send_check(skb, iph->saddr, iph->daddr); 49 } 50 51 return tcp_gso_segment(skb, features); 52 } 53 54 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 55 netdev_features_t features) 56 { 57 struct sk_buff *segs = ERR_PTR(-EINVAL); 58 unsigned int sum_truesize = 0; 59 struct tcphdr *th; 60 unsigned int thlen; 61 unsigned int seq; 62 __be32 delta; 63 unsigned int oldlen; 64 unsigned int mss; 65 struct sk_buff *gso_skb = skb; 66 __sum16 newcheck; 67 bool ooo_okay, copy_destructor; 68 69 th = tcp_hdr(skb); 70 thlen = th->doff * 4; 71 if (thlen < sizeof(*th)) 72 goto out; 73 74 if (!pskb_may_pull(skb, thlen)) 75 goto out; 76 77 oldlen = (u16)~skb->len; 78 __skb_pull(skb, thlen); 79 80 mss = tcp_skb_mss(skb); 81 if (unlikely(skb->len <= mss)) 82 goto out; 83 84 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 85 /* Packet is from an untrusted source, reset gso_segs. */ 86 int type = skb_shinfo(skb)->gso_type; 87 88 if (unlikely(type & 89 ~(SKB_GSO_TCPV4 | 90 SKB_GSO_DODGY | 91 SKB_GSO_TCP_ECN | 92 SKB_GSO_TCPV6 | 93 SKB_GSO_GRE | 94 SKB_GSO_GRE_CSUM | 95 SKB_GSO_IPIP | 96 SKB_GSO_SIT | 97 SKB_GSO_MPLS | 98 SKB_GSO_UDP_TUNNEL | 99 SKB_GSO_UDP_TUNNEL_CSUM | 100 0) || 101 !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))) 102 goto out; 103 104 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 105 106 segs = NULL; 107 goto out; 108 } 109 110 copy_destructor = gso_skb->destructor == tcp_wfree; 111 ooo_okay = gso_skb->ooo_okay; 112 /* All segments but the first should have ooo_okay cleared */ 113 skb->ooo_okay = 0; 114 115 segs = skb_segment(skb, features); 116 if (IS_ERR(segs)) 117 goto out; 118 119 /* Only first segment might have ooo_okay set */ 120 segs->ooo_okay = ooo_okay; 121 122 delta = htonl(oldlen + (thlen + mss)); 123 124 skb = segs; 125 th = tcp_hdr(skb); 126 seq = ntohl(th->seq); 127 128 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP)) 129 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss); 130 131 newcheck = ~csum_fold((__force __wsum)((__force u32)th->check + 132 (__force u32)delta)); 133 134 do { 135 th->fin = th->psh = 0; 136 th->check = newcheck; 137 138 if (skb->ip_summed != CHECKSUM_PARTIAL) 139 th->check = gso_make_checksum(skb, ~th->check); 140 141 seq += mss; 142 if (copy_destructor) { 143 skb->destructor = gso_skb->destructor; 144 skb->sk = gso_skb->sk; 145 sum_truesize += skb->truesize; 146 } 147 skb = skb->next; 148 th = tcp_hdr(skb); 149 150 th->seq = htonl(seq); 151 th->cwr = 0; 152 } while (skb->next); 153 154 /* Following permits TCP Small Queues to work well with GSO : 155 * The callback to TCP stack will be called at the time last frag 156 * is freed at TX completion, and not right now when gso_skb 157 * is freed by GSO engine 158 */ 159 if (copy_destructor) { 160 swap(gso_skb->sk, skb->sk); 161 swap(gso_skb->destructor, skb->destructor); 162 sum_truesize += skb->truesize; 163 atomic_add(sum_truesize - gso_skb->truesize, 164 &skb->sk->sk_wmem_alloc); 165 } 166 167 delta = htonl(oldlen + (skb_tail_pointer(skb) - 168 skb_transport_header(skb)) + 169 skb->data_len); 170 th->check = ~csum_fold((__force __wsum)((__force u32)th->check + 171 (__force u32)delta)); 172 if (skb->ip_summed != CHECKSUM_PARTIAL) 173 th->check = gso_make_checksum(skb, ~th->check); 174 out: 175 return segs; 176 } 177 178 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb) 179 { 180 struct sk_buff **pp = NULL; 181 struct sk_buff *p; 182 struct tcphdr *th; 183 struct tcphdr *th2; 184 unsigned int len; 185 unsigned int thlen; 186 __be32 flags; 187 unsigned int mss = 1; 188 unsigned int hlen; 189 unsigned int off; 190 int flush = 1; 191 int i; 192 193 off = skb_gro_offset(skb); 194 hlen = off + sizeof(*th); 195 th = skb_gro_header_fast(skb, off); 196 if (skb_gro_header_hard(skb, hlen)) { 197 th = skb_gro_header_slow(skb, hlen, off); 198 if (unlikely(!th)) 199 goto out; 200 } 201 202 thlen = th->doff * 4; 203 if (thlen < sizeof(*th)) 204 goto out; 205 206 hlen = off + thlen; 207 if (skb_gro_header_hard(skb, hlen)) { 208 th = skb_gro_header_slow(skb, hlen, off); 209 if (unlikely(!th)) 210 goto out; 211 } 212 213 skb_gro_pull(skb, thlen); 214 215 len = skb_gro_len(skb); 216 flags = tcp_flag_word(th); 217 218 for (; (p = *head); head = &p->next) { 219 if (!NAPI_GRO_CB(p)->same_flow) 220 continue; 221 222 th2 = tcp_hdr(p); 223 224 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 225 NAPI_GRO_CB(p)->same_flow = 0; 226 continue; 227 } 228 229 goto found; 230 } 231 232 goto out_check_final; 233 234 found: 235 /* Include the IP ID check below from the inner most IP hdr */ 236 flush = NAPI_GRO_CB(p)->flush | NAPI_GRO_CB(p)->flush_id; 237 flush |= (__force int)(flags & TCP_FLAG_CWR); 238 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 239 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 240 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 241 for (i = sizeof(*th); i < thlen; i += 4) 242 flush |= *(u32 *)((u8 *)th + i) ^ 243 *(u32 *)((u8 *)th2 + i); 244 245 mss = tcp_skb_mss(p); 246 247 flush |= (len - 1) >= mss; 248 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 249 250 if (flush || skb_gro_receive(head, skb)) { 251 mss = 1; 252 goto out_check_final; 253 } 254 255 p = *head; 256 th2 = tcp_hdr(p); 257 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 258 259 out_check_final: 260 flush = len < mss; 261 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 262 TCP_FLAG_RST | TCP_FLAG_SYN | 263 TCP_FLAG_FIN)); 264 265 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 266 pp = head; 267 268 out: 269 NAPI_GRO_CB(skb)->flush |= (flush != 0); 270 271 return pp; 272 } 273 274 int tcp_gro_complete(struct sk_buff *skb) 275 { 276 struct tcphdr *th = tcp_hdr(skb); 277 278 skb->csum_start = (unsigned char *)th - skb->head; 279 skb->csum_offset = offsetof(struct tcphdr, check); 280 skb->ip_summed = CHECKSUM_PARTIAL; 281 282 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 283 284 if (th->cwr) 285 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 286 287 return 0; 288 } 289 EXPORT_SYMBOL(tcp_gro_complete); 290 291 static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb) 292 { 293 /* Don't bother verifying checksum if we're going to flush anyway. */ 294 if (!NAPI_GRO_CB(skb)->flush && 295 skb_gro_checksum_validate(skb, IPPROTO_TCP, 296 inet_gro_compute_pseudo)) { 297 NAPI_GRO_CB(skb)->flush = 1; 298 return NULL; 299 } 300 301 return tcp_gro_receive(head, skb); 302 } 303 304 static int tcp4_gro_complete(struct sk_buff *skb, int thoff) 305 { 306 const struct iphdr *iph = ip_hdr(skb); 307 struct tcphdr *th = tcp_hdr(skb); 308 309 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, 310 iph->daddr, 0); 311 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4; 312 313 return tcp_gro_complete(skb); 314 } 315 316 static const struct net_offload tcpv4_offload = { 317 .callbacks = { 318 .gso_segment = tcp4_gso_segment, 319 .gro_receive = tcp4_gro_receive, 320 .gro_complete = tcp4_gro_complete, 321 }, 322 }; 323 324 int __init tcpv4_offload_init(void) 325 { 326 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 327 } 328