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/indirect_call_wrapper.h> 14 #include <linux/skbuff.h> 15 #include <net/tcp.h> 16 #include <net/protocol.h> 17 18 static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq, 19 unsigned int seq, unsigned int mss) 20 { 21 while (skb) { 22 if (before(ts_seq, seq + mss)) { 23 skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP; 24 skb_shinfo(skb)->tskey = ts_seq; 25 return; 26 } 27 28 skb = skb->next; 29 seq += mss; 30 } 31 } 32 33 static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb, 34 netdev_features_t features) 35 { 36 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)) 37 return ERR_PTR(-EINVAL); 38 39 if (!pskb_may_pull(skb, sizeof(struct tcphdr))) 40 return ERR_PTR(-EINVAL); 41 42 if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) { 43 const struct iphdr *iph = ip_hdr(skb); 44 struct tcphdr *th = tcp_hdr(skb); 45 46 /* Set up checksum pseudo header, usually expect stack to 47 * have done this already. 48 */ 49 50 th->check = 0; 51 skb->ip_summed = CHECKSUM_PARTIAL; 52 __tcp_v4_send_check(skb, iph->saddr, iph->daddr); 53 } 54 55 return tcp_gso_segment(skb, features); 56 } 57 58 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 59 netdev_features_t features) 60 { 61 struct sk_buff *segs = ERR_PTR(-EINVAL); 62 unsigned int sum_truesize = 0; 63 struct tcphdr *th; 64 unsigned int thlen; 65 unsigned int seq; 66 __be32 delta; 67 unsigned int oldlen; 68 unsigned int mss; 69 struct sk_buff *gso_skb = skb; 70 __sum16 newcheck; 71 bool ooo_okay, copy_destructor; 72 73 th = tcp_hdr(skb); 74 thlen = th->doff * 4; 75 if (thlen < sizeof(*th)) 76 goto out; 77 78 if (!pskb_may_pull(skb, thlen)) 79 goto out; 80 81 oldlen = (u16)~skb->len; 82 __skb_pull(skb, thlen); 83 84 mss = skb_shinfo(skb)->gso_size; 85 if (unlikely(skb->len <= mss)) 86 goto out; 87 88 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 89 /* Packet is from an untrusted source, reset gso_segs. */ 90 91 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 92 93 segs = NULL; 94 goto out; 95 } 96 97 copy_destructor = gso_skb->destructor == tcp_wfree; 98 ooo_okay = gso_skb->ooo_okay; 99 /* All segments but the first should have ooo_okay cleared */ 100 skb->ooo_okay = 0; 101 102 segs = skb_segment(skb, features); 103 if (IS_ERR(segs)) 104 goto out; 105 106 /* Only first segment might have ooo_okay set */ 107 segs->ooo_okay = ooo_okay; 108 109 /* GSO partial and frag_list segmentation only requires splitting 110 * the frame into an MSS multiple and possibly a remainder, both 111 * cases return a GSO skb. So update the mss now. 112 */ 113 if (skb_is_gso(segs)) 114 mss *= skb_shinfo(segs)->gso_segs; 115 116 delta = htonl(oldlen + (thlen + mss)); 117 118 skb = segs; 119 th = tcp_hdr(skb); 120 seq = ntohl(th->seq); 121 122 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP)) 123 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss); 124 125 newcheck = ~csum_fold((__force __wsum)((__force u32)th->check + 126 (__force u32)delta)); 127 128 while (skb->next) { 129 th->fin = th->psh = 0; 130 th->check = newcheck; 131 132 if (skb->ip_summed == CHECKSUM_PARTIAL) 133 gso_reset_checksum(skb, ~th->check); 134 else 135 th->check = gso_make_checksum(skb, ~th->check); 136 137 seq += mss; 138 if (copy_destructor) { 139 skb->destructor = gso_skb->destructor; 140 skb->sk = gso_skb->sk; 141 sum_truesize += skb->truesize; 142 } 143 skb = skb->next; 144 th = tcp_hdr(skb); 145 146 th->seq = htonl(seq); 147 th->cwr = 0; 148 } 149 150 /* Following permits TCP Small Queues to work well with GSO : 151 * The callback to TCP stack will be called at the time last frag 152 * is freed at TX completion, and not right now when gso_skb 153 * is freed by GSO engine 154 */ 155 if (copy_destructor) { 156 int delta; 157 158 swap(gso_skb->sk, skb->sk); 159 swap(gso_skb->destructor, skb->destructor); 160 sum_truesize += skb->truesize; 161 delta = sum_truesize - gso_skb->truesize; 162 /* In some pathological cases, delta can be negative. 163 * We need to either use refcount_add() or refcount_sub_and_test() 164 */ 165 if (likely(delta >= 0)) 166 refcount_add(delta, &skb->sk->sk_wmem_alloc); 167 else 168 WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc)); 169 } 170 171 delta = htonl(oldlen + (skb_tail_pointer(skb) - 172 skb_transport_header(skb)) + 173 skb->data_len); 174 th->check = ~csum_fold((__force __wsum)((__force u32)th->check + 175 (__force u32)delta)); 176 if (skb->ip_summed == CHECKSUM_PARTIAL) 177 gso_reset_checksum(skb, ~th->check); 178 else 179 th->check = gso_make_checksum(skb, ~th->check); 180 out: 181 return segs; 182 } 183 184 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb) 185 { 186 struct sk_buff *pp = NULL; 187 struct sk_buff *p; 188 struct tcphdr *th; 189 struct tcphdr *th2; 190 unsigned int len; 191 unsigned int thlen; 192 __be32 flags; 193 unsigned int mss = 1; 194 unsigned int hlen; 195 unsigned int off; 196 int flush = 1; 197 int i; 198 199 off = skb_gro_offset(skb); 200 hlen = off + sizeof(*th); 201 th = skb_gro_header_fast(skb, off); 202 if (skb_gro_header_hard(skb, hlen)) { 203 th = skb_gro_header_slow(skb, hlen, off); 204 if (unlikely(!th)) 205 goto out; 206 } 207 208 thlen = th->doff * 4; 209 if (thlen < sizeof(*th)) 210 goto out; 211 212 hlen = off + thlen; 213 if (skb_gro_header_hard(skb, hlen)) { 214 th = skb_gro_header_slow(skb, hlen, off); 215 if (unlikely(!th)) 216 goto out; 217 } 218 219 skb_gro_pull(skb, thlen); 220 221 len = skb_gro_len(skb); 222 flags = tcp_flag_word(th); 223 224 list_for_each_entry(p, head, list) { 225 if (!NAPI_GRO_CB(p)->same_flow) 226 continue; 227 228 th2 = tcp_hdr(p); 229 230 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 231 NAPI_GRO_CB(p)->same_flow = 0; 232 continue; 233 } 234 235 goto found; 236 } 237 p = NULL; 238 goto out_check_final; 239 240 found: 241 /* Include the IP ID check below from the inner most IP hdr */ 242 flush = NAPI_GRO_CB(p)->flush; 243 flush |= (__force int)(flags & TCP_FLAG_CWR); 244 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 245 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 246 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 247 for (i = sizeof(*th); i < thlen; i += 4) 248 flush |= *(u32 *)((u8 *)th + i) ^ 249 *(u32 *)((u8 *)th2 + i); 250 251 /* When we receive our second frame we can made a decision on if we 252 * continue this flow as an atomic flow with a fixed ID or if we use 253 * an incrementing ID. 254 */ 255 if (NAPI_GRO_CB(p)->flush_id != 1 || 256 NAPI_GRO_CB(p)->count != 1 || 257 !NAPI_GRO_CB(p)->is_atomic) 258 flush |= NAPI_GRO_CB(p)->flush_id; 259 else 260 NAPI_GRO_CB(p)->is_atomic = false; 261 262 mss = skb_shinfo(p)->gso_size; 263 264 flush |= (len - 1) >= mss; 265 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 266 #ifdef CONFIG_TLS_DEVICE 267 flush |= p->decrypted ^ skb->decrypted; 268 #endif 269 270 if (flush || skb_gro_receive(p, skb)) { 271 mss = 1; 272 goto out_check_final; 273 } 274 275 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 276 277 out_check_final: 278 flush = len < mss; 279 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 280 TCP_FLAG_RST | TCP_FLAG_SYN | 281 TCP_FLAG_FIN)); 282 283 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 284 pp = p; 285 286 out: 287 NAPI_GRO_CB(skb)->flush |= (flush != 0); 288 289 return pp; 290 } 291 292 int tcp_gro_complete(struct sk_buff *skb) 293 { 294 struct tcphdr *th = tcp_hdr(skb); 295 296 skb->csum_start = (unsigned char *)th - skb->head; 297 skb->csum_offset = offsetof(struct tcphdr, check); 298 skb->ip_summed = CHECKSUM_PARTIAL; 299 300 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 301 302 if (th->cwr) 303 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 304 305 return 0; 306 } 307 EXPORT_SYMBOL(tcp_gro_complete); 308 309 INDIRECT_CALLABLE_SCOPE 310 struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb) 311 { 312 /* Don't bother verifying checksum if we're going to flush anyway. */ 313 if (!NAPI_GRO_CB(skb)->flush && 314 skb_gro_checksum_validate(skb, IPPROTO_TCP, 315 inet_gro_compute_pseudo)) { 316 NAPI_GRO_CB(skb)->flush = 1; 317 return NULL; 318 } 319 320 return tcp_gro_receive(head, skb); 321 } 322 323 INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff) 324 { 325 const struct iphdr *iph = ip_hdr(skb); 326 struct tcphdr *th = tcp_hdr(skb); 327 328 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, 329 iph->daddr, 0); 330 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4; 331 332 if (NAPI_GRO_CB(skb)->is_atomic) 333 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID; 334 335 return tcp_gro_complete(skb); 336 } 337 338 static const struct net_offload tcpv4_offload = { 339 .callbacks = { 340 .gso_segment = tcp4_gso_segment, 341 .gro_receive = tcp4_gro_receive, 342 .gro_complete = tcp4_gro_complete, 343 }, 344 }; 345 346 int __init tcpv4_offload_init(void) 347 { 348 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 349 } 350