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 __be32 delta; 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 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 = (u16)~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 = 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((__force __wsum)((__force u32)th->check + 123 (__force u32)delta)); 124 125 while (skb->next) { 126 th->fin = th->psh = 0; 127 th->check = newcheck; 128 129 if (skb->ip_summed == CHECKSUM_PARTIAL) 130 gso_reset_checksum(skb, ~th->check); 131 else 132 th->check = gso_make_checksum(skb, ~th->check); 133 134 seq += mss; 135 if (copy_destructor) { 136 skb->destructor = gso_skb->destructor; 137 skb->sk = gso_skb->sk; 138 sum_truesize += skb->truesize; 139 } 140 skb = skb->next; 141 th = tcp_hdr(skb); 142 143 th->seq = htonl(seq); 144 th->cwr = 0; 145 } 146 147 /* Following permits TCP Small Queues to work well with GSO : 148 * The callback to TCP stack will be called at the time last frag 149 * is freed at TX completion, and not right now when gso_skb 150 * is freed by GSO engine 151 */ 152 if (copy_destructor) { 153 int delta; 154 155 swap(gso_skb->sk, skb->sk); 156 swap(gso_skb->destructor, skb->destructor); 157 sum_truesize += skb->truesize; 158 delta = sum_truesize - gso_skb->truesize; 159 /* In some pathological cases, delta can be negative. 160 * We need to either use refcount_add() or refcount_sub_and_test() 161 */ 162 if (likely(delta >= 0)) 163 refcount_add(delta, &skb->sk->sk_wmem_alloc); 164 else 165 WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc)); 166 } 167 168 delta = htonl(oldlen + (skb_tail_pointer(skb) - 169 skb_transport_header(skb)) + 170 skb->data_len); 171 th->check = ~csum_fold((__force __wsum)((__force u32)th->check + 172 (__force u32)delta)); 173 if (skb->ip_summed == CHECKSUM_PARTIAL) 174 gso_reset_checksum(skb, ~th->check); 175 else 176 th->check = gso_make_checksum(skb, ~th->check); 177 out: 178 return segs; 179 } 180 181 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb) 182 { 183 struct sk_buff *pp = NULL; 184 struct sk_buff *p; 185 struct tcphdr *th; 186 struct tcphdr *th2; 187 unsigned int len; 188 unsigned int thlen; 189 __be32 flags; 190 unsigned int mss = 1; 191 unsigned int hlen; 192 unsigned int off; 193 int flush = 1; 194 int i; 195 196 off = skb_gro_offset(skb); 197 hlen = off + sizeof(*th); 198 th = skb_gro_header(skb, hlen, off); 199 if (unlikely(!th)) 200 goto out; 201 202 thlen = th->doff * 4; 203 if (thlen < sizeof(*th)) 204 goto out; 205 206 hlen = off + thlen; 207 if (skb_gro_header_hard(skb, hlen)) { 208 th = skb_gro_header_slow(skb, hlen, off); 209 if (unlikely(!th)) 210 goto out; 211 } 212 213 skb_gro_pull(skb, thlen); 214 215 len = skb_gro_len(skb); 216 flags = tcp_flag_word(th); 217 218 list_for_each_entry(p, head, list) { 219 if (!NAPI_GRO_CB(p)->same_flow) 220 continue; 221 222 th2 = tcp_hdr(p); 223 224 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 225 NAPI_GRO_CB(p)->same_flow = 0; 226 continue; 227 } 228 229 goto found; 230 } 231 p = NULL; 232 goto out_check_final; 233 234 found: 235 /* Include the IP ID check below from the inner most IP hdr */ 236 flush = NAPI_GRO_CB(p)->flush; 237 flush |= (__force int)(flags & TCP_FLAG_CWR); 238 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 239 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 240 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 241 for (i = sizeof(*th); i < thlen; i += 4) 242 flush |= *(u32 *)((u8 *)th + i) ^ 243 *(u32 *)((u8 *)th2 + i); 244 245 /* When we receive our second frame we can made a decision on if we 246 * continue this flow as an atomic flow with a fixed ID or if we use 247 * an incrementing ID. 248 */ 249 if (NAPI_GRO_CB(p)->flush_id != 1 || 250 NAPI_GRO_CB(p)->count != 1 || 251 !NAPI_GRO_CB(p)->is_atomic) 252 flush |= NAPI_GRO_CB(p)->flush_id; 253 else 254 NAPI_GRO_CB(p)->is_atomic = false; 255 256 mss = skb_shinfo(p)->gso_size; 257 258 /* If skb is a GRO packet, make sure its gso_size matches prior packet mss. 259 * If it is a single frame, do not aggregate it if its length 260 * is bigger than our mss. 261 */ 262 if (unlikely(skb_is_gso(skb))) 263 flush |= (mss != skb_shinfo(skb)->gso_size); 264 else 265 flush |= (len - 1) >= mss; 266 267 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 268 #ifdef CONFIG_TLS_DEVICE 269 flush |= p->decrypted ^ skb->decrypted; 270 #endif 271 272 if (flush || skb_gro_receive(p, skb)) { 273 mss = 1; 274 goto out_check_final; 275 } 276 277 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 278 279 out_check_final: 280 /* Force a flush if last segment is smaller than mss. */ 281 if (unlikely(skb_is_gso(skb))) 282 flush = len != NAPI_GRO_CB(skb)->count * skb_shinfo(skb)->gso_size; 283 else 284 flush = len < mss; 285 286 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 287 TCP_FLAG_RST | TCP_FLAG_SYN | 288 TCP_FLAG_FIN)); 289 290 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 291 pp = p; 292 293 out: 294 NAPI_GRO_CB(skb)->flush |= (flush != 0); 295 296 return pp; 297 } 298 299 int tcp_gro_complete(struct sk_buff *skb) 300 { 301 struct tcphdr *th = tcp_hdr(skb); 302 303 skb->csum_start = (unsigned char *)th - skb->head; 304 skb->csum_offset = offsetof(struct tcphdr, check); 305 skb->ip_summed = CHECKSUM_PARTIAL; 306 307 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 308 309 if (th->cwr) 310 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 311 312 if (skb->encapsulation) 313 skb->inner_transport_header = skb->transport_header; 314 315 return 0; 316 } 317 EXPORT_SYMBOL(tcp_gro_complete); 318 319 INDIRECT_CALLABLE_SCOPE 320 struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb) 321 { 322 /* Don't bother verifying checksum if we're going to flush anyway. */ 323 if (!NAPI_GRO_CB(skb)->flush && 324 skb_gro_checksum_validate(skb, IPPROTO_TCP, 325 inet_gro_compute_pseudo)) { 326 NAPI_GRO_CB(skb)->flush = 1; 327 return NULL; 328 } 329 330 return tcp_gro_receive(head, skb); 331 } 332 333 INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff) 334 { 335 const struct iphdr *iph = ip_hdr(skb); 336 struct tcphdr *th = tcp_hdr(skb); 337 338 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, 339 iph->daddr, 0); 340 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4; 341 342 if (NAPI_GRO_CB(skb)->is_atomic) 343 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID; 344 345 return tcp_gro_complete(skb); 346 } 347 348 static const struct net_offload tcpv4_offload = { 349 .callbacks = { 350 .gso_segment = tcp4_gso_segment, 351 .gro_receive = tcp4_gro_receive, 352 .gro_complete = tcp4_gro_complete, 353 }, 354 }; 355 356 int __init tcpv4_offload_init(void) 357 { 358 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 359 } 360