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/tcp.h> 12 #include <net/protocol.h> 13 14 static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq, 15 unsigned int seq, unsigned int mss) 16 { 17 while (skb) { 18 if (before(ts_seq, seq + mss)) { 19 skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP; 20 skb_shinfo(skb)->tskey = ts_seq; 21 return; 22 } 23 24 skb = skb->next; 25 seq += mss; 26 } 27 } 28 29 static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb, 30 netdev_features_t features) 31 { 32 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)) 33 return ERR_PTR(-EINVAL); 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 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 = htonl(oldlen + (skb_tail_pointer(skb) - 168 skb_transport_header(skb)) + 169 skb->data_len); 170 th->check = ~csum_fold((__force __wsum)((__force u32)th->check + 171 (__force u32)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_fast(skb, off); 198 if (skb_gro_header_hard(skb, hlen)) { 199 th = skb_gro_header_slow(skb, hlen, off); 200 if (unlikely(!th)) 201 goto out; 202 } 203 204 thlen = th->doff * 4; 205 if (thlen < sizeof(*th)) 206 goto out; 207 208 hlen = off + thlen; 209 if (skb_gro_header_hard(skb, hlen)) { 210 th = skb_gro_header_slow(skb, hlen, off); 211 if (unlikely(!th)) 212 goto out; 213 } 214 215 skb_gro_pull(skb, thlen); 216 217 len = skb_gro_len(skb); 218 flags = tcp_flag_word(th); 219 220 list_for_each_entry(p, head, list) { 221 if (!NAPI_GRO_CB(p)->same_flow) 222 continue; 223 224 th2 = tcp_hdr(p); 225 226 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 227 NAPI_GRO_CB(p)->same_flow = 0; 228 continue; 229 } 230 231 goto found; 232 } 233 p = NULL; 234 goto out_check_final; 235 236 found: 237 /* Include the IP ID check below from the inner most IP hdr */ 238 flush = NAPI_GRO_CB(p)->flush; 239 flush |= (__force int)(flags & TCP_FLAG_CWR); 240 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 241 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 242 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 243 for (i = sizeof(*th); i < thlen; i += 4) 244 flush |= *(u32 *)((u8 *)th + i) ^ 245 *(u32 *)((u8 *)th2 + i); 246 247 /* When we receive our second frame we can made a decision on if we 248 * continue this flow as an atomic flow with a fixed ID or if we use 249 * an incrementing ID. 250 */ 251 if (NAPI_GRO_CB(p)->flush_id != 1 || 252 NAPI_GRO_CB(p)->count != 1 || 253 !NAPI_GRO_CB(p)->is_atomic) 254 flush |= NAPI_GRO_CB(p)->flush_id; 255 else 256 NAPI_GRO_CB(p)->is_atomic = false; 257 258 mss = skb_shinfo(p)->gso_size; 259 260 flush |= (len - 1) >= mss; 261 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 262 #ifdef CONFIG_TLS_DEVICE 263 flush |= p->decrypted ^ skb->decrypted; 264 #endif 265 266 if (flush || skb_gro_receive(p, skb)) { 267 mss = 1; 268 goto out_check_final; 269 } 270 271 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 272 273 out_check_final: 274 flush = len < mss; 275 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 276 TCP_FLAG_RST | TCP_FLAG_SYN | 277 TCP_FLAG_FIN)); 278 279 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 280 pp = p; 281 282 out: 283 NAPI_GRO_CB(skb)->flush |= (flush != 0); 284 285 return pp; 286 } 287 288 int tcp_gro_complete(struct sk_buff *skb) 289 { 290 struct tcphdr *th = tcp_hdr(skb); 291 292 skb->csum_start = (unsigned char *)th - skb->head; 293 skb->csum_offset = offsetof(struct tcphdr, check); 294 skb->ip_summed = CHECKSUM_PARTIAL; 295 296 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 297 298 if (th->cwr) 299 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 300 301 if (skb->encapsulation) 302 skb->inner_transport_header = skb->transport_header; 303 304 return 0; 305 } 306 EXPORT_SYMBOL(tcp_gro_complete); 307 308 INDIRECT_CALLABLE_SCOPE 309 struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb) 310 { 311 /* Don't bother verifying checksum if we're going to flush anyway. */ 312 if (!NAPI_GRO_CB(skb)->flush && 313 skb_gro_checksum_validate(skb, IPPROTO_TCP, 314 inet_gro_compute_pseudo)) { 315 NAPI_GRO_CB(skb)->flush = 1; 316 return NULL; 317 } 318 319 return tcp_gro_receive(head, skb); 320 } 321 322 INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff) 323 { 324 const struct iphdr *iph = ip_hdr(skb); 325 struct tcphdr *th = tcp_hdr(skb); 326 327 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, 328 iph->daddr, 0); 329 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4; 330 331 if (NAPI_GRO_CB(skb)->is_atomic) 332 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID; 333 334 return tcp_gro_complete(skb); 335 } 336 337 static const struct net_offload tcpv4_offload = { 338 .callbacks = { 339 .gso_segment = tcp4_gso_segment, 340 .gro_receive = tcp4_gro_receive, 341 .gro_complete = tcp4_gro_complete, 342 }, 343 }; 344 345 int __init tcpv4_offload_init(void) 346 { 347 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); 348 } 349