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 static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
33 netdev_features_t features)
35 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
36 return ERR_PTR(-EINVAL);
38 if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
39 const struct iphdr *iph = ip_hdr(skb);
40 struct tcphdr *th = tcp_hdr(skb);
42 /* Set up checksum pseudo header, usually expect stack to
43 * have done this already.
47 skb->ip_summed = CHECKSUM_PARTIAL;
48 __tcp_v4_send_check(skb, iph->saddr, iph->daddr);
51 return tcp_gso_segment(skb, features);
54 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
55 netdev_features_t features)
57 struct sk_buff *segs = ERR_PTR(-EINVAL);
58 unsigned int sum_truesize = 0;
65 struct sk_buff *gso_skb = skb;
67 bool ooo_okay, copy_destructor;
71 if (thlen < sizeof(*th))
74 if (!pskb_may_pull(skb, thlen))
77 oldlen = (u16)~skb->len;
78 __skb_pull(skb, thlen);
80 mss = skb_shinfo(skb)->gso_size;
81 if (unlikely(skb->len <= mss))
84 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
85 /* Packet is from an untrusted source, reset gso_segs. */
87 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
93 /* GSO partial only requires splitting the frame into an MSS
94 * multiple and possibly a remainder. So update the mss now.
96 if (features & NETIF_F_GSO_PARTIAL)
97 mss = skb->len - (skb->len % mss);
99 copy_destructor = gso_skb->destructor == tcp_wfree;
100 ooo_okay = gso_skb->ooo_okay;
101 /* All segments but the first should have ooo_okay cleared */
104 segs = skb_segment(skb, features);
108 /* Only first segment might have ooo_okay set */
109 segs->ooo_okay = ooo_okay;
111 delta = htonl(oldlen + (thlen + mss));
115 seq = ntohl(th->seq);
117 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
118 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);
120 newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
121 (__force u32)delta));
124 th->fin = th->psh = 0;
125 th->check = newcheck;
127 if (skb->ip_summed == CHECKSUM_PARTIAL)
128 gso_reset_checksum(skb, ~th->check);
130 th->check = gso_make_checksum(skb, ~th->check);
133 if (copy_destructor) {
134 skb->destructor = gso_skb->destructor;
135 skb->sk = gso_skb->sk;
136 sum_truesize += skb->truesize;
141 th->seq = htonl(seq);
145 /* Following permits TCP Small Queues to work well with GSO :
146 * The callback to TCP stack will be called at the time last frag
147 * is freed at TX completion, and not right now when gso_skb
148 * is freed by GSO engine
150 if (copy_destructor) {
151 swap(gso_skb->sk, skb->sk);
152 swap(gso_skb->destructor, skb->destructor);
153 sum_truesize += skb->truesize;
154 atomic_add(sum_truesize - gso_skb->truesize,
155 &skb->sk->sk_wmem_alloc);
158 delta = htonl(oldlen + (skb_tail_pointer(skb) -
159 skb_transport_header(skb)) +
161 th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
162 (__force u32)delta));
163 if (skb->ip_summed == CHECKSUM_PARTIAL)
164 gso_reset_checksum(skb, ~th->check);
166 th->check = gso_make_checksum(skb, ~th->check);
171 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
173 struct sk_buff **pp = NULL;
180 unsigned int mss = 1;
186 off = skb_gro_offset(skb);
187 hlen = off + sizeof(*th);
188 th = skb_gro_header_fast(skb, off);
189 if (skb_gro_header_hard(skb, hlen)) {
190 th = skb_gro_header_slow(skb, hlen, off);
195 thlen = th->doff * 4;
196 if (thlen < sizeof(*th))
200 if (skb_gro_header_hard(skb, hlen)) {
201 th = skb_gro_header_slow(skb, hlen, off);
206 skb_gro_pull(skb, thlen);
208 len = skb_gro_len(skb);
209 flags = tcp_flag_word(th);
211 for (; (p = *head); head = &p->next) {
212 if (!NAPI_GRO_CB(p)->same_flow)
217 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
218 NAPI_GRO_CB(p)->same_flow = 0;
225 goto out_check_final;
228 /* Include the IP ID check below from the inner most IP hdr */
229 flush = NAPI_GRO_CB(p)->flush;
230 flush |= (__force int)(flags & TCP_FLAG_CWR);
231 flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
232 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
233 flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
234 for (i = sizeof(*th); i < thlen; i += 4)
235 flush |= *(u32 *)((u8 *)th + i) ^
236 *(u32 *)((u8 *)th2 + i);
238 /* When we receive our second frame we can made a decision on if we
239 * continue this flow as an atomic flow with a fixed ID or if we use
240 * an incrementing ID.
242 if (NAPI_GRO_CB(p)->flush_id != 1 ||
243 NAPI_GRO_CB(p)->count != 1 ||
244 !NAPI_GRO_CB(p)->is_atomic)
245 flush |= NAPI_GRO_CB(p)->flush_id;
247 NAPI_GRO_CB(p)->is_atomic = false;
249 mss = skb_shinfo(p)->gso_size;
251 flush |= (len - 1) >= mss;
252 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
254 if (flush || skb_gro_receive(head, skb)) {
256 goto out_check_final;
261 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
265 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
266 TCP_FLAG_RST | TCP_FLAG_SYN |
269 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
273 NAPI_GRO_CB(skb)->flush |= (flush != 0);
278 int tcp_gro_complete(struct sk_buff *skb)
280 struct tcphdr *th = tcp_hdr(skb);
282 skb->csum_start = (unsigned char *)th - skb->head;
283 skb->csum_offset = offsetof(struct tcphdr, check);
284 skb->ip_summed = CHECKSUM_PARTIAL;
286 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
289 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
293 EXPORT_SYMBOL(tcp_gro_complete);
295 static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
297 /* Don't bother verifying checksum if we're going to flush anyway. */
298 if (!NAPI_GRO_CB(skb)->flush &&
299 skb_gro_checksum_validate(skb, IPPROTO_TCP,
300 inet_gro_compute_pseudo)) {
301 NAPI_GRO_CB(skb)->flush = 1;
305 return tcp_gro_receive(head, skb);
308 static int tcp4_gro_complete(struct sk_buff *skb, int thoff)
310 const struct iphdr *iph = ip_hdr(skb);
311 struct tcphdr *th = tcp_hdr(skb);
313 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
315 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
317 if (NAPI_GRO_CB(skb)->is_atomic)
318 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID;
320 return tcp_gro_complete(skb);
323 static const struct net_offload tcpv4_offload = {
325 .gso_segment = tcp4_gso_segment,
326 .gro_receive = tcp4_gro_receive,
327 .gro_complete = tcp4_gro_complete,
331 int __init tcpv4_offload_init(void)
333 return inet_add_offload(&tcpv4_offload, IPPROTO_TCP);