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/tcp.h> 13 #include <net/protocol.h> 14 15 static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq, 16 unsigned int seq, unsigned int mss) 17 { 18 while (skb) { 19 if (before(ts_seq, seq + mss)) { 20 skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP; 21 skb_shinfo(skb)->tskey = ts_seq; 22 return; 23 } 24 25 skb = skb->next; 26 seq += mss; 27 } 28 } 29 30 static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb, 31 netdev_features_t features) 32 { 33 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)) 34 return ERR_PTR(-EINVAL); 35 36 if (!pskb_may_pull(skb, sizeof(struct tcphdr))) 37 return ERR_PTR(-EINVAL); 38 39 if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) { 40 const struct iphdr *iph = ip_hdr(skb); 41 struct tcphdr *th = tcp_hdr(skb); 42 43 /* Set up checksum pseudo header, usually expect stack to 44 * have done this already. 45 */ 46 47 th->check = 0; 48 skb->ip_summed = CHECKSUM_PARTIAL; 49 __tcp_v4_send_check(skb, iph->saddr, iph->daddr); 50 } 51 52 return tcp_gso_segment(skb, features); 53 } 54 55 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 56 netdev_features_t features) 57 { 58 struct sk_buff *segs = ERR_PTR(-EINVAL); 59 unsigned int sum_truesize = 0; 60 struct tcphdr *th; 61 unsigned int thlen; 62 unsigned int seq; 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 __wsum delta; 69 70 th = tcp_hdr(skb); 71 thlen = th->doff * 4; 72 if (thlen < sizeof(*th)) 73 goto out; 74 75 if (!pskb_may_pull(skb, thlen)) 76 goto out; 77 78 oldlen = ~skb->len; 79 __skb_pull(skb, thlen); 80 81 mss = skb_shinfo(skb)->gso_size; 82 if (unlikely(skb->len <= mss)) 83 goto out; 84 85 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 86 /* Packet is from an untrusted source, reset gso_segs. */ 87 88 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 89 90 segs = NULL; 91 goto out; 92 } 93 94 copy_destructor = gso_skb->destructor == tcp_wfree; 95 ooo_okay = gso_skb->ooo_okay; 96 /* All segments but the first should have ooo_okay cleared */ 97 skb->ooo_okay = 0; 98 99 segs = skb_segment(skb, features); 100 if (IS_ERR(segs)) 101 goto out; 102 103 /* Only first segment might have ooo_okay set */ 104 segs->ooo_okay = ooo_okay; 105 106 /* GSO partial and frag_list segmentation only requires splitting 107 * the frame into an MSS multiple and possibly a remainder, both 108 * cases return a GSO skb. So update the mss now. 109 */ 110 if (skb_is_gso(segs)) 111 mss *= skb_shinfo(segs)->gso_segs; 112 113 delta = (__force __wsum)htonl(oldlen + thlen + mss); 114 115 skb = segs; 116 th = tcp_hdr(skb); 117 seq = ntohl(th->seq); 118 119 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP)) 120 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss); 121 122 newcheck = ~csum_fold(csum_add(csum_unfold(th->check), 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 int delta; 153 154 swap(gso_skb->sk, skb->sk); 155 swap(gso_skb->destructor, skb->destructor); 156 sum_truesize += skb->truesize; 157 delta = sum_truesize - gso_skb->truesize; 158 /* In some pathological cases, delta can be negative. 159 * We need to either use refcount_add() or refcount_sub_and_test() 160 */ 161 if (likely(delta >= 0)) 162 refcount_add(delta, &skb->sk->sk_wmem_alloc); 163 else 164 WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc)); 165 } 166 167 delta = (__force __wsum)htonl(oldlen + 168 (skb_tail_pointer(skb) - 169 skb_transport_header(skb)) + 170 skb->data_len); 171 th->check = ~csum_fold(csum_add(csum_unfold(th->check), delta)); 172 if (skb->ip_summed == CHECKSUM_PARTIAL) 173 gso_reset_checksum(skb, ~th->check); 174 else 175 th->check = gso_make_checksum(skb, ~th->check); 176 out: 177 return segs; 178 } 179 180 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb) 181 { 182 struct sk_buff *pp = NULL; 183 struct sk_buff *p; 184 struct tcphdr *th; 185 struct tcphdr *th2; 186 unsigned int len; 187 unsigned int thlen; 188 __be32 flags; 189 unsigned int mss = 1; 190 unsigned int hlen; 191 unsigned int off; 192 int flush = 1; 193 int i; 194 195 off = skb_gro_offset(skb); 196 hlen = off + sizeof(*th); 197 th = skb_gro_header(skb, hlen, off); 198 if (unlikely(!th)) 199 goto out; 200 201 thlen = th->doff * 4; 202 if (thlen < sizeof(*th)) 203 goto out; 204 205 hlen = off + thlen; 206 if (skb_gro_header_hard(skb, hlen)) { 207 th = skb_gro_header_slow(skb, hlen, off); 208 if (unlikely(!th)) 209 goto out; 210 } 211 212 skb_gro_pull(skb, thlen); 213 214 len = skb_gro_len(skb); 215 flags = tcp_flag_word(th); 216 217 list_for_each_entry(p, head, list) { 218 if (!NAPI_GRO_CB(p)->same_flow) 219 continue; 220 221 th2 = tcp_hdr(p); 222 223 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 224 NAPI_GRO_CB(p)->same_flow = 0; 225 continue; 226 } 227 228 goto found; 229 } 230 p = NULL; 231 goto out_check_final; 232 233 found: 234 /* Include the IP ID check below from the inner most IP hdr */ 235 flush = NAPI_GRO_CB(p)->flush; 236 flush |= (__force int)(flags & TCP_FLAG_CWR); 237 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 238 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 239 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 240 for (i = sizeof(*th); i < thlen; i += 4) 241 flush |= *(u32 *)((u8 *)th + i) ^ 242 *(u32 *)((u8 *)th2 + i); 243 244 /* When we receive our second frame we can made a decision on if we 245 * continue this flow as an atomic flow with a fixed ID or if we use 246 * an incrementing ID. 247 */ 248 if (NAPI_GRO_CB(p)->flush_id != 1 || 249 NAPI_GRO_CB(p)->count != 1 || 250 !NAPI_GRO_CB(p)->is_atomic) 251 flush |= NAPI_GRO_CB(p)->flush_id; 252 else 253 NAPI_GRO_CB(p)->is_atomic = false; 254 255 mss = skb_shinfo(p)->gso_size; 256 257 /* If skb is a GRO packet, make sure its gso_size matches prior packet mss. 258 * If it is a single frame, do not aggregate it if its length 259 * is bigger than our mss. 260 */ 261 if (unlikely(skb_is_gso(skb))) 262 flush |= (mss != skb_shinfo(skb)->gso_size); 263 else 264 flush |= (len - 1) >= mss; 265 266 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 267 #ifdef CONFIG_TLS_DEVICE 268 flush |= p->decrypted ^ skb->decrypted; 269 #endif 270 271 if (flush || skb_gro_receive(p, skb)) { 272 mss = 1; 273 goto out_check_final; 274 } 275 276 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 277 278 out_check_final: 279 /* Force a flush if last segment is smaller than mss. */ 280 if (unlikely(skb_is_gso(skb))) 281 flush = len != NAPI_GRO_CB(skb)->count * skb_shinfo(skb)->gso_size; 282 else 283 flush = len < mss; 284 285 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 286 TCP_FLAG_RST | TCP_FLAG_SYN | 287 TCP_FLAG_FIN)); 288 289 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 290 pp = p; 291 292 out: 293 NAPI_GRO_CB(skb)->flush |= (flush != 0); 294 295 return pp; 296 } 297 298 void tcp_gro_complete(struct sk_buff *skb) 299 { 300 struct tcphdr *th = tcp_hdr(skb); 301 302 skb->csum_start = (unsigned char *)th - skb->head; 303 skb->csum_offset = offsetof(struct tcphdr, check); 304 skb->ip_summed = CHECKSUM_PARTIAL; 305 306 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 307 308 if (th->cwr) 309 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 310 311 if (skb->encapsulation) 312 skb->inner_transport_header = skb->transport_header; 313 } 314 EXPORT_SYMBOL(tcp_gro_complete); 315 316 INDIRECT_CALLABLE_SCOPE 317 struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb) 318 { 319 /* Don't bother verifying checksum if we're going to flush anyway. */ 320 if (!NAPI_GRO_CB(skb)->flush && 321 skb_gro_checksum_validate(skb, IPPROTO_TCP, 322 inet_gro_compute_pseudo)) { 323 NAPI_GRO_CB(skb)->flush = 1; 324 return NULL; 325 } 326 327 return tcp_gro_receive(head, skb); 328 } 329 330 INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff) 331 { 332 const struct iphdr *iph = ip_hdr(skb); 333 struct tcphdr *th = tcp_hdr(skb); 334 335 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, 336 iph->daddr, 0); 337 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4; 338 339 if (NAPI_GRO_CB(skb)->is_atomic) 340 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID; 341 342 tcp_gro_complete(skb); 343 return 0; 344 } 345 346 static const struct net_offload tcpv4_offload = { 347 .callbacks = { 348 .gso_segment = tcp4_gso_segment, 349 .gro_receive = tcp4_gro_receive, 350 .gro_complete = tcp4_gro_complete, 351 }, 352 }; 353 354 int __init tcpv4_offload_init(void) 355 { 356 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 357 } 358