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 copy_destructor = gso_skb->destructor == tcp_wfree; 94 ooo_okay = gso_skb->ooo_okay; 95 /* All segments but the first should have ooo_okay cleared */ 96 skb->ooo_okay = 0; 97 98 segs = skb_segment(skb, features); 99 if (IS_ERR(segs)) 100 goto out; 101 102 /* Only first segment might have ooo_okay set */ 103 segs->ooo_okay = ooo_okay; 104 105 /* GSO partial and frag_list segmentation only requires splitting 106 * the frame into an MSS multiple and possibly a remainder, both 107 * cases return a GSO skb. So update the mss now. 108 */ 109 if (skb_is_gso(segs)) 110 mss *= skb_shinfo(segs)->gso_segs; 111 112 delta = htonl(oldlen + (thlen + mss)); 113 114 skb = segs; 115 th = tcp_hdr(skb); 116 seq = ntohl(th->seq); 117 118 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP)) 119 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss); 120 121 newcheck = ~csum_fold((__force __wsum)((__force u32)th->check + 122 (__force u32)delta)); 123 124 while (skb->next) { 125 th->fin = th->psh = 0; 126 th->check = newcheck; 127 128 if (skb->ip_summed == CHECKSUM_PARTIAL) 129 gso_reset_checksum(skb, ~th->check); 130 else 131 th->check = gso_make_checksum(skb, ~th->check); 132 133 seq += mss; 134 if (copy_destructor) { 135 skb->destructor = gso_skb->destructor; 136 skb->sk = gso_skb->sk; 137 sum_truesize += skb->truesize; 138 } 139 skb = skb->next; 140 th = tcp_hdr(skb); 141 142 th->seq = htonl(seq); 143 th->cwr = 0; 144 } 145 146 /* Following permits TCP Small Queues to work well with GSO : 147 * The callback to TCP stack will be called at the time last frag 148 * is freed at TX completion, and not right now when gso_skb 149 * is freed by GSO engine 150 */ 151 if (copy_destructor) { 152 swap(gso_skb->sk, skb->sk); 153 swap(gso_skb->destructor, skb->destructor); 154 sum_truesize += skb->truesize; 155 refcount_add(sum_truesize - gso_skb->truesize, 156 &skb->sk->sk_wmem_alloc); 157 } 158 159 delta = htonl(oldlen + (skb_tail_pointer(skb) - 160 skb_transport_header(skb)) + 161 skb->data_len); 162 th->check = ~csum_fold((__force __wsum)((__force u32)th->check + 163 (__force u32)delta)); 164 if (skb->ip_summed == CHECKSUM_PARTIAL) 165 gso_reset_checksum(skb, ~th->check); 166 else 167 th->check = gso_make_checksum(skb, ~th->check); 168 out: 169 return segs; 170 } 171 172 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb) 173 { 174 struct sk_buff **pp = NULL; 175 struct sk_buff *p; 176 struct tcphdr *th; 177 struct tcphdr *th2; 178 unsigned int len; 179 unsigned int thlen; 180 __be32 flags; 181 unsigned int mss = 1; 182 unsigned int hlen; 183 unsigned int off; 184 int flush = 1; 185 int i; 186 187 off = skb_gro_offset(skb); 188 hlen = off + sizeof(*th); 189 th = skb_gro_header_fast(skb, off); 190 if (skb_gro_header_hard(skb, hlen)) { 191 th = skb_gro_header_slow(skb, hlen, off); 192 if (unlikely(!th)) 193 goto out; 194 } 195 196 thlen = th->doff * 4; 197 if (thlen < sizeof(*th)) 198 goto out; 199 200 hlen = off + thlen; 201 if (skb_gro_header_hard(skb, hlen)) { 202 th = skb_gro_header_slow(skb, hlen, off); 203 if (unlikely(!th)) 204 goto out; 205 } 206 207 skb_gro_pull(skb, thlen); 208 209 len = skb_gro_len(skb); 210 flags = tcp_flag_word(th); 211 212 for (; (p = *head); head = &p->next) { 213 if (!NAPI_GRO_CB(p)->same_flow) 214 continue; 215 216 th2 = tcp_hdr(p); 217 218 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 219 NAPI_GRO_CB(p)->same_flow = 0; 220 continue; 221 } 222 223 goto found; 224 } 225 226 goto out_check_final; 227 228 found: 229 /* Include the IP ID check below from the inner most IP hdr */ 230 flush = NAPI_GRO_CB(p)->flush; 231 flush |= (__force int)(flags & TCP_FLAG_CWR); 232 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 233 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 234 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 235 for (i = sizeof(*th); i < thlen; i += 4) 236 flush |= *(u32 *)((u8 *)th + i) ^ 237 *(u32 *)((u8 *)th2 + i); 238 239 /* When we receive our second frame we can made a decision on if we 240 * continue this flow as an atomic flow with a fixed ID or if we use 241 * an incrementing ID. 242 */ 243 if (NAPI_GRO_CB(p)->flush_id != 1 || 244 NAPI_GRO_CB(p)->count != 1 || 245 !NAPI_GRO_CB(p)->is_atomic) 246 flush |= NAPI_GRO_CB(p)->flush_id; 247 else 248 NAPI_GRO_CB(p)->is_atomic = false; 249 250 mss = skb_shinfo(p)->gso_size; 251 252 flush |= (len - 1) >= mss; 253 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 254 255 if (flush || skb_gro_receive(head, skb)) { 256 mss = 1; 257 goto out_check_final; 258 } 259 260 p = *head; 261 th2 = tcp_hdr(p); 262 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 263 264 out_check_final: 265 flush = len < mss; 266 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 267 TCP_FLAG_RST | TCP_FLAG_SYN | 268 TCP_FLAG_FIN)); 269 270 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 271 pp = head; 272 273 out: 274 NAPI_GRO_CB(skb)->flush |= (flush != 0); 275 276 return pp; 277 } 278 279 int tcp_gro_complete(struct sk_buff *skb) 280 { 281 struct tcphdr *th = tcp_hdr(skb); 282 283 skb->csum_start = (unsigned char *)th - skb->head; 284 skb->csum_offset = offsetof(struct tcphdr, check); 285 skb->ip_summed = CHECKSUM_PARTIAL; 286 287 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 288 289 if (th->cwr) 290 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 291 292 return 0; 293 } 294 EXPORT_SYMBOL(tcp_gro_complete); 295 296 static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb) 297 { 298 /* Don't bother verifying checksum if we're going to flush anyway. */ 299 if (!NAPI_GRO_CB(skb)->flush && 300 skb_gro_checksum_validate(skb, IPPROTO_TCP, 301 inet_gro_compute_pseudo)) { 302 NAPI_GRO_CB(skb)->flush = 1; 303 return NULL; 304 } 305 306 return tcp_gro_receive(head, skb); 307 } 308 309 static int tcp4_gro_complete(struct sk_buff *skb, int thoff) 310 { 311 const struct iphdr *iph = ip_hdr(skb); 312 struct tcphdr *th = tcp_hdr(skb); 313 314 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, 315 iph->daddr, 0); 316 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4; 317 318 if (NAPI_GRO_CB(skb)->is_atomic) 319 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID; 320 321 return tcp_gro_complete(skb); 322 } 323 324 static const struct net_offload tcpv4_offload = { 325 .callbacks = { 326 .gso_segment = tcp4_gso_segment, 327 .gro_receive = tcp4_gro_receive, 328 .gro_complete = tcp4_gro_complete, 329 }, 330 }; 331 332 int __init tcpv4_offload_init(void) 333 { 334 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 335 } 336