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 static 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 = skb_shinfo(skb)->gso_size; 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 87 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 88 89 segs = NULL; 90 goto out; 91 } 92 93 /* GSO partial only requires splitting the frame into an MSS 94 * multiple and possibly a remainder. So update the mss now. 95 */ 96 if (features & NETIF_F_GSO_PARTIAL) 97 mss = skb->len - (skb->len % mss); 98 99 copy_destructor = gso_skb->destructor == tcp_wfree; 100 ooo_okay = gso_skb->ooo_okay; 101 /* All segments but the first should have ooo_okay cleared */ 102 skb->ooo_okay = 0; 103 104 segs = skb_segment(skb, features); 105 if (IS_ERR(segs)) 106 goto out; 107 108 /* Only first segment might have ooo_okay set */ 109 segs->ooo_okay = ooo_okay; 110 111 delta = htonl(oldlen + (thlen + mss)); 112 113 skb = segs; 114 th = tcp_hdr(skb); 115 seq = ntohl(th->seq); 116 117 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP)) 118 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss); 119 120 newcheck = ~csum_fold((__force __wsum)((__force u32)th->check + 121 (__force u32)delta)); 122 123 while (skb->next) { 124 th->fin = th->psh = 0; 125 th->check = newcheck; 126 127 if (skb->ip_summed == CHECKSUM_PARTIAL) 128 gso_reset_checksum(skb, ~th->check); 129 else 130 th->check = gso_make_checksum(skb, ~th->check); 131 132 seq += mss; 133 if (copy_destructor) { 134 skb->destructor = gso_skb->destructor; 135 skb->sk = gso_skb->sk; 136 sum_truesize += skb->truesize; 137 } 138 skb = skb->next; 139 th = tcp_hdr(skb); 140 141 th->seq = htonl(seq); 142 th->cwr = 0; 143 } 144 145 /* Following permits TCP Small Queues to work well with GSO : 146 * The callback to TCP stack will be called at the time last frag 147 * is freed at TX completion, and not right now when gso_skb 148 * is freed by GSO engine 149 */ 150 if (copy_destructor) { 151 swap(gso_skb->sk, skb->sk); 152 swap(gso_skb->destructor, skb->destructor); 153 sum_truesize += skb->truesize; 154 atomic_add(sum_truesize - gso_skb->truesize, 155 &skb->sk->sk_wmem_alloc); 156 } 157 158 delta = htonl(oldlen + (skb_tail_pointer(skb) - 159 skb_transport_header(skb)) + 160 skb->data_len); 161 th->check = ~csum_fold((__force __wsum)((__force u32)th->check + 162 (__force u32)delta)); 163 if (skb->ip_summed == CHECKSUM_PARTIAL) 164 gso_reset_checksum(skb, ~th->check); 165 else 166 th->check = gso_make_checksum(skb, ~th->check); 167 out: 168 return segs; 169 } 170 171 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb) 172 { 173 struct sk_buff **pp = NULL; 174 struct sk_buff *p; 175 struct tcphdr *th; 176 struct tcphdr *th2; 177 unsigned int len; 178 unsigned int thlen; 179 __be32 flags; 180 unsigned int mss = 1; 181 unsigned int hlen; 182 unsigned int off; 183 int flush = 1; 184 int i; 185 186 off = skb_gro_offset(skb); 187 hlen = off + sizeof(*th); 188 th = skb_gro_header_fast(skb, off); 189 if (skb_gro_header_hard(skb, hlen)) { 190 th = skb_gro_header_slow(skb, hlen, off); 191 if (unlikely(!th)) 192 goto out; 193 } 194 195 thlen = th->doff * 4; 196 if (thlen < sizeof(*th)) 197 goto out; 198 199 hlen = off + thlen; 200 if (skb_gro_header_hard(skb, hlen)) { 201 th = skb_gro_header_slow(skb, hlen, off); 202 if (unlikely(!th)) 203 goto out; 204 } 205 206 skb_gro_pull(skb, thlen); 207 208 len = skb_gro_len(skb); 209 flags = tcp_flag_word(th); 210 211 for (; (p = *head); head = &p->next) { 212 if (!NAPI_GRO_CB(p)->same_flow) 213 continue; 214 215 th2 = tcp_hdr(p); 216 217 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 218 NAPI_GRO_CB(p)->same_flow = 0; 219 continue; 220 } 221 222 goto found; 223 } 224 225 goto out_check_final; 226 227 found: 228 /* Include the IP ID check below from the inner most IP hdr */ 229 flush = NAPI_GRO_CB(p)->flush; 230 flush |= (__force int)(flags & TCP_FLAG_CWR); 231 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 232 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 233 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 234 for (i = sizeof(*th); i < thlen; i += 4) 235 flush |= *(u32 *)((u8 *)th + i) ^ 236 *(u32 *)((u8 *)th2 + i); 237 238 /* When we receive our second frame we can made a decision on if we 239 * continue this flow as an atomic flow with a fixed ID or if we use 240 * an incrementing ID. 241 */ 242 if (NAPI_GRO_CB(p)->flush_id != 1 || 243 NAPI_GRO_CB(p)->count != 1 || 244 !NAPI_GRO_CB(p)->is_atomic) 245 flush |= NAPI_GRO_CB(p)->flush_id; 246 else 247 NAPI_GRO_CB(p)->is_atomic = false; 248 249 mss = skb_shinfo(p)->gso_size; 250 251 flush |= (len - 1) >= mss; 252 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 253 254 if (flush || skb_gro_receive(head, skb)) { 255 mss = 1; 256 goto out_check_final; 257 } 258 259 p = *head; 260 th2 = tcp_hdr(p); 261 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 262 263 out_check_final: 264 flush = len < mss; 265 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 266 TCP_FLAG_RST | TCP_FLAG_SYN | 267 TCP_FLAG_FIN)); 268 269 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 270 pp = head; 271 272 out: 273 NAPI_GRO_CB(skb)->flush |= (flush != 0); 274 275 return pp; 276 } 277 278 int tcp_gro_complete(struct sk_buff *skb) 279 { 280 struct tcphdr *th = tcp_hdr(skb); 281 282 skb->csum_start = (unsigned char *)th - skb->head; 283 skb->csum_offset = offsetof(struct tcphdr, check); 284 skb->ip_summed = CHECKSUM_PARTIAL; 285 286 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 287 288 if (th->cwr) 289 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 290 291 return 0; 292 } 293 EXPORT_SYMBOL(tcp_gro_complete); 294 295 static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb) 296 { 297 /* Don't bother verifying checksum if we're going to flush anyway. */ 298 if (!NAPI_GRO_CB(skb)->flush && 299 skb_gro_checksum_validate(skb, IPPROTO_TCP, 300 inet_gro_compute_pseudo)) { 301 NAPI_GRO_CB(skb)->flush = 1; 302 return NULL; 303 } 304 305 return tcp_gro_receive(head, skb); 306 } 307 308 static int tcp4_gro_complete(struct sk_buff *skb, int thoff) 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 - thoff, iph->saddr, 314 iph->daddr, 0); 315 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4; 316 317 if (NAPI_GRO_CB(skb)->is_atomic) 318 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID; 319 320 return tcp_gro_complete(skb); 321 } 322 323 static const struct net_offload tcpv4_offload = { 324 .callbacks = { 325 .gso_segment = tcp4_gso_segment, 326 .gro_receive = tcp4_gro_receive, 327 .gro_complete = tcp4_gro_complete, 328 }, 329 }; 330 331 int __init tcpv4_offload_init(void) 332 { 333 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 334 } 335