2 * IPV4 GSO/GRO offload support
3 * Linux INET implementation
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.
10 * TCPv4 GSO/GRO support
13 #include <linux/skbuff.h>
15 #include <net/protocol.h>
17 static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
18 unsigned int seq, unsigned int mss)
21 if (before(ts_seq, seq + mss)) {
22 skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP;
23 skb_shinfo(skb)->tskey = ts_seq;
32 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
33 netdev_features_t features)
35 struct sk_buff *segs = ERR_PTR(-EINVAL);
36 unsigned int sum_truesize = 0;
43 struct sk_buff *gso_skb = skb;
45 bool ooo_okay, copy_destructor;
47 if (!pskb_may_pull(skb, sizeof(*th)))
52 if (thlen < sizeof(*th))
55 if (!pskb_may_pull(skb, thlen))
58 oldlen = (u16)~skb->len;
59 __skb_pull(skb, thlen);
61 mss = tcp_skb_mss(skb);
62 if (unlikely(skb->len <= mss))
65 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
66 /* Packet is from an untrusted source, reset gso_segs. */
67 int type = skb_shinfo(skb)->gso_type;
80 SKB_GSO_UDP_TUNNEL_CSUM |
82 !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
85 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
91 copy_destructor = gso_skb->destructor == tcp_wfree;
92 ooo_okay = gso_skb->ooo_okay;
93 /* All segments but the first should have ooo_okay cleared */
96 segs = skb_segment(skb, features);
100 /* Only first segment might have ooo_okay set */
101 segs->ooo_okay = ooo_okay;
103 delta = htonl(oldlen + (thlen + mss));
107 seq = ntohl(th->seq);
109 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
110 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);
112 newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
113 (__force u32)delta));
116 th->fin = th->psh = 0;
117 th->check = newcheck;
119 if (skb->ip_summed != CHECKSUM_PARTIAL)
120 th->check = gso_make_checksum(skb, ~th->check);
123 if (copy_destructor) {
124 skb->destructor = gso_skb->destructor;
125 skb->sk = gso_skb->sk;
126 sum_truesize += skb->truesize;
131 th->seq = htonl(seq);
135 /* Following permits TCP Small Queues to work well with GSO :
136 * The callback to TCP stack will be called at the time last frag
137 * is freed at TX completion, and not right now when gso_skb
138 * is freed by GSO engine
140 if (copy_destructor) {
141 swap(gso_skb->sk, skb->sk);
142 swap(gso_skb->destructor, skb->destructor);
143 sum_truesize += skb->truesize;
144 atomic_add(sum_truesize - gso_skb->truesize,
145 &skb->sk->sk_wmem_alloc);
148 delta = htonl(oldlen + (skb_tail_pointer(skb) -
149 skb_transport_header(skb)) +
151 th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
152 (__force u32)delta));
153 if (skb->ip_summed != CHECKSUM_PARTIAL)
154 th->check = gso_make_checksum(skb, ~th->check);
159 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
161 struct sk_buff **pp = NULL;
168 unsigned int mss = 1;
174 off = skb_gro_offset(skb);
175 hlen = off + sizeof(*th);
176 th = skb_gro_header_fast(skb, off);
177 if (skb_gro_header_hard(skb, hlen)) {
178 th = skb_gro_header_slow(skb, hlen, off);
183 thlen = th->doff * 4;
184 if (thlen < sizeof(*th))
188 if (skb_gro_header_hard(skb, hlen)) {
189 th = skb_gro_header_slow(skb, hlen, off);
194 skb_gro_pull(skb, thlen);
196 len = skb_gro_len(skb);
197 flags = tcp_flag_word(th);
199 for (; (p = *head); head = &p->next) {
200 if (!NAPI_GRO_CB(p)->same_flow)
205 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
206 NAPI_GRO_CB(p)->same_flow = 0;
213 goto out_check_final;
216 /* Include the IP ID check below from the inner most IP hdr */
217 flush = NAPI_GRO_CB(p)->flush | NAPI_GRO_CB(p)->flush_id;
218 flush |= (__force int)(flags & TCP_FLAG_CWR);
219 flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
220 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
221 flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
222 for (i = sizeof(*th); i < thlen; i += 4)
223 flush |= *(u32 *)((u8 *)th + i) ^
224 *(u32 *)((u8 *)th2 + i);
226 mss = tcp_skb_mss(p);
228 flush |= (len - 1) >= mss;
229 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
231 if (flush || skb_gro_receive(head, skb)) {
233 goto out_check_final;
238 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
242 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
243 TCP_FLAG_RST | TCP_FLAG_SYN |
246 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
250 NAPI_GRO_CB(skb)->flush |= (flush != 0);
255 int tcp_gro_complete(struct sk_buff *skb)
257 struct tcphdr *th = tcp_hdr(skb);
259 skb->csum_start = (unsigned char *)th - skb->head;
260 skb->csum_offset = offsetof(struct tcphdr, check);
261 skb->ip_summed = CHECKSUM_PARTIAL;
263 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
266 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
270 EXPORT_SYMBOL(tcp_gro_complete);
272 static int tcp_v4_gso_send_check(struct sk_buff *skb)
274 const struct iphdr *iph;
277 if (!pskb_may_pull(skb, sizeof(*th)))
284 skb->ip_summed = CHECKSUM_PARTIAL;
285 __tcp_v4_send_check(skb, iph->saddr, iph->daddr);
289 static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
291 /* Use the IP hdr immediately proceeding for this transport */
292 const struct iphdr *iph = skb_gro_network_header(skb);
295 /* Don't bother verifying checksum if we're going to flush anyway. */
296 if (NAPI_GRO_CB(skb)->flush)
299 wsum = NAPI_GRO_CB(skb)->csum;
301 switch (skb->ip_summed) {
303 wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb),
308 case CHECKSUM_COMPLETE:
309 if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
311 skb->ip_summed = CHECKSUM_UNNECESSARY;
315 NAPI_GRO_CB(skb)->flush = 1;
320 return tcp_gro_receive(head, skb);
323 static int tcp4_gro_complete(struct sk_buff *skb, int thoff)
325 const struct iphdr *iph = ip_hdr(skb);
326 struct tcphdr *th = tcp_hdr(skb);
328 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
330 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
332 return tcp_gro_complete(skb);
335 static const struct net_offload tcpv4_offload = {
337 .gso_send_check = tcp_v4_gso_send_check,
338 .gso_segment = tcp_gso_segment,
339 .gro_receive = tcp4_gro_receive,
340 .gro_complete = tcp4_gro_complete,
344 int __init tcpv4_offload_init(void)
346 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP);