1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * IPV4 GSO/GRO offload support 4 * Linux INET implementation 5 * 6 * TCPv4 GSO/GRO support 7 */ 8 9 #include <linux/indirect_call_wrapper.h> 10 #include <linux/skbuff.h> 11 #include <net/gro.h> 12 #include <net/gso.h> 13 #include <net/tcp.h> 14 #include <net/protocol.h> 15 16 static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq, 17 unsigned int seq, unsigned int mss) 18 { 19 while (skb) { 20 if (before(ts_seq, seq + mss)) { 21 skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP; 22 skb_shinfo(skb)->tskey = ts_seq; 23 return; 24 } 25 26 skb = skb->next; 27 seq += mss; 28 } 29 } 30 31 static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb, 32 netdev_features_t features) 33 { 34 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)) 35 return ERR_PTR(-EINVAL); 36 37 if (!pskb_may_pull(skb, sizeof(struct tcphdr))) 38 return ERR_PTR(-EINVAL); 39 40 if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) { 41 const struct iphdr *iph = ip_hdr(skb); 42 struct tcphdr *th = tcp_hdr(skb); 43 44 /* Set up checksum pseudo header, usually expect stack to 45 * have done this already. 46 */ 47 48 th->check = 0; 49 skb->ip_summed = CHECKSUM_PARTIAL; 50 __tcp_v4_send_check(skb, iph->saddr, iph->daddr); 51 } 52 53 return tcp_gso_segment(skb, features); 54 } 55 56 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 57 netdev_features_t features) 58 { 59 struct sk_buff *segs = ERR_PTR(-EINVAL); 60 unsigned int sum_truesize = 0; 61 struct tcphdr *th; 62 unsigned int thlen; 63 unsigned int seq; 64 unsigned int oldlen; 65 unsigned int mss; 66 struct sk_buff *gso_skb = skb; 67 __sum16 newcheck; 68 bool ooo_okay, copy_destructor; 69 __wsum delta; 70 71 th = tcp_hdr(skb); 72 thlen = th->doff * 4; 73 if (thlen < sizeof(*th)) 74 goto out; 75 76 if (unlikely(skb_checksum_start(skb) != skb_transport_header(skb))) 77 goto out; 78 79 if (!pskb_may_pull(skb, thlen)) 80 goto out; 81 82 oldlen = ~skb->len; 83 __skb_pull(skb, thlen); 84 85 mss = skb_shinfo(skb)->gso_size; 86 if (unlikely(skb->len <= mss)) 87 goto out; 88 89 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 90 /* Packet is from an untrusted source, reset gso_segs. */ 91 92 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 93 94 segs = NULL; 95 goto out; 96 } 97 98 copy_destructor = gso_skb->destructor == tcp_wfree; 99 ooo_okay = gso_skb->ooo_okay; 100 /* All segments but the first should have ooo_okay cleared */ 101 skb->ooo_okay = 0; 102 103 segs = skb_segment(skb, features); 104 if (IS_ERR(segs)) 105 goto out; 106 107 /* Only first segment might have ooo_okay set */ 108 segs->ooo_okay = ooo_okay; 109 110 /* GSO partial and frag_list segmentation only requires splitting 111 * the frame into an MSS multiple and possibly a remainder, both 112 * cases return a GSO skb. So update the mss now. 113 */ 114 if (skb_is_gso(segs)) 115 mss *= skb_shinfo(segs)->gso_segs; 116 117 delta = (__force __wsum)htonl(oldlen + thlen + mss); 118 119 skb = segs; 120 th = tcp_hdr(skb); 121 seq = ntohl(th->seq); 122 123 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP)) 124 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss); 125 126 newcheck = ~csum_fold(csum_add(csum_unfold(th->check), 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 = (__force __wsum)htonl(oldlen + 172 (skb_tail_pointer(skb) - 173 skb_transport_header(skb)) + 174 skb->data_len); 175 th->check = ~csum_fold(csum_add(csum_unfold(th->check), 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(skb, hlen, off); 202 if (unlikely(!th)) 203 goto out; 204 205 thlen = th->doff * 4; 206 if (thlen < sizeof(*th)) 207 goto out; 208 209 hlen = off + thlen; 210 if (skb_gro_header_hard(skb, hlen)) { 211 th = skb_gro_header_slow(skb, hlen, off); 212 if (unlikely(!th)) 213 goto out; 214 } 215 216 skb_gro_pull(skb, thlen); 217 218 len = skb_gro_len(skb); 219 flags = tcp_flag_word(th); 220 221 list_for_each_entry(p, head, list) { 222 if (!NAPI_GRO_CB(p)->same_flow) 223 continue; 224 225 th2 = tcp_hdr(p); 226 227 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 228 NAPI_GRO_CB(p)->same_flow = 0; 229 continue; 230 } 231 232 goto found; 233 } 234 p = NULL; 235 goto out_check_final; 236 237 found: 238 /* Include the IP ID check below from the inner most IP hdr */ 239 flush = NAPI_GRO_CB(p)->flush; 240 flush |= (__force int)(flags & TCP_FLAG_CWR); 241 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 242 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 243 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 244 for (i = sizeof(*th); i < thlen; i += 4) 245 flush |= *(u32 *)((u8 *)th + i) ^ 246 *(u32 *)((u8 *)th2 + i); 247 248 /* When we receive our second frame we can made a decision on if we 249 * continue this flow as an atomic flow with a fixed ID or if we use 250 * an incrementing ID. 251 */ 252 if (NAPI_GRO_CB(p)->flush_id != 1 || 253 NAPI_GRO_CB(p)->count != 1 || 254 !NAPI_GRO_CB(p)->is_atomic) 255 flush |= NAPI_GRO_CB(p)->flush_id; 256 else 257 NAPI_GRO_CB(p)->is_atomic = false; 258 259 mss = skb_shinfo(p)->gso_size; 260 261 /* If skb is a GRO packet, make sure its gso_size matches prior packet mss. 262 * If it is a single frame, do not aggregate it if its length 263 * is bigger than our mss. 264 */ 265 if (unlikely(skb_is_gso(skb))) 266 flush |= (mss != skb_shinfo(skb)->gso_size); 267 else 268 flush |= (len - 1) >= mss; 269 270 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 271 #ifdef CONFIG_TLS_DEVICE 272 flush |= p->decrypted ^ skb->decrypted; 273 #endif 274 275 if (flush || skb_gro_receive(p, skb)) { 276 mss = 1; 277 goto out_check_final; 278 } 279 280 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 281 282 out_check_final: 283 /* Force a flush if last segment is smaller than mss. */ 284 if (unlikely(skb_is_gso(skb))) 285 flush = len != NAPI_GRO_CB(skb)->count * skb_shinfo(skb)->gso_size; 286 else 287 flush = len < mss; 288 289 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 290 TCP_FLAG_RST | TCP_FLAG_SYN | 291 TCP_FLAG_FIN)); 292 293 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 294 pp = p; 295 296 out: 297 NAPI_GRO_CB(skb)->flush |= (flush != 0); 298 299 return pp; 300 } 301 302 void tcp_gro_complete(struct sk_buff *skb) 303 { 304 struct tcphdr *th = tcp_hdr(skb); 305 306 skb->csum_start = (unsigned char *)th - skb->head; 307 skb->csum_offset = offsetof(struct tcphdr, check); 308 skb->ip_summed = CHECKSUM_PARTIAL; 309 310 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 311 312 if (th->cwr) 313 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 314 315 if (skb->encapsulation) 316 skb->inner_transport_header = skb->transport_header; 317 } 318 EXPORT_SYMBOL(tcp_gro_complete); 319 320 INDIRECT_CALLABLE_SCOPE 321 struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb) 322 { 323 /* Don't bother verifying checksum if we're going to flush anyway. */ 324 if (!NAPI_GRO_CB(skb)->flush && 325 skb_gro_checksum_validate(skb, IPPROTO_TCP, 326 inet_gro_compute_pseudo)) { 327 NAPI_GRO_CB(skb)->flush = 1; 328 return NULL; 329 } 330 331 return tcp_gro_receive(head, skb); 332 } 333 334 INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff) 335 { 336 const struct iphdr *iph = ip_hdr(skb); 337 struct tcphdr *th = tcp_hdr(skb); 338 339 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, 340 iph->daddr, 0); 341 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4; 342 343 if (NAPI_GRO_CB(skb)->is_atomic) 344 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID; 345 346 tcp_gro_complete(skb); 347 return 0; 348 } 349 350 static const struct net_offload tcpv4_offload = { 351 .callbacks = { 352 .gso_segment = tcp4_gso_segment, 353 .gro_receive = tcp4_gro_receive, 354 .gro_complete = tcp4_gro_complete, 355 }, 356 }; 357 358 int __init tcpv4_offload_init(void) 359 { 360 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 361 } 362