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28850dc7 DB |
1 | /* |
2 | * IPV4 GSO/GRO offload support | |
3 | * Linux INET implementation | |
4 | * | |
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. | |
9 | * | |
10 | * TCPv4 GSO/GRO support | |
11 | */ | |
12 | ||
13 | #include <linux/skbuff.h> | |
14 | #include <net/tcp.h> | |
15 | #include <net/protocol.h> | |
16 | ||
17 | struct sk_buff *tcp_tso_segment(struct sk_buff *skb, | |
18 | netdev_features_t features) | |
19 | { | |
20 | struct sk_buff *segs = ERR_PTR(-EINVAL); | |
21 | struct tcphdr *th; | |
22 | unsigned int thlen; | |
23 | unsigned int seq; | |
24 | __be32 delta; | |
25 | unsigned int oldlen; | |
26 | unsigned int mss; | |
27 | struct sk_buff *gso_skb = skb; | |
28 | __sum16 newcheck; | |
29 | bool ooo_okay, copy_destructor; | |
30 | ||
31 | if (!pskb_may_pull(skb, sizeof(*th))) | |
32 | goto out; | |
33 | ||
34 | th = tcp_hdr(skb); | |
35 | thlen = th->doff * 4; | |
36 | if (thlen < sizeof(*th)) | |
37 | goto out; | |
38 | ||
39 | if (!pskb_may_pull(skb, thlen)) | |
40 | goto out; | |
41 | ||
42 | oldlen = (u16)~skb->len; | |
43 | __skb_pull(skb, thlen); | |
44 | ||
45 | mss = tcp_skb_mss(skb); | |
46 | if (unlikely(skb->len <= mss)) | |
47 | goto out; | |
48 | ||
49 | if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { | |
50 | /* Packet is from an untrusted source, reset gso_segs. */ | |
51 | int type = skb_shinfo(skb)->gso_type; | |
52 | ||
53 | if (unlikely(type & | |
54 | ~(SKB_GSO_TCPV4 | | |
55 | SKB_GSO_DODGY | | |
56 | SKB_GSO_TCP_ECN | | |
57 | SKB_GSO_TCPV6 | | |
58 | SKB_GSO_GRE | | |
59 | SKB_GSO_MPLS | | |
60 | SKB_GSO_UDP_TUNNEL | | |
61 | 0) || | |
62 | !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))) | |
63 | goto out; | |
64 | ||
65 | skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); | |
66 | ||
67 | segs = NULL; | |
68 | goto out; | |
69 | } | |
70 | ||
71 | copy_destructor = gso_skb->destructor == tcp_wfree; | |
72 | ooo_okay = gso_skb->ooo_okay; | |
73 | /* All segments but the first should have ooo_okay cleared */ | |
74 | skb->ooo_okay = 0; | |
75 | ||
76 | segs = skb_segment(skb, features); | |
77 | if (IS_ERR(segs)) | |
78 | goto out; | |
79 | ||
80 | /* Only first segment might have ooo_okay set */ | |
81 | segs->ooo_okay = ooo_okay; | |
82 | ||
83 | delta = htonl(oldlen + (thlen + mss)); | |
84 | ||
85 | skb = segs; | |
86 | th = tcp_hdr(skb); | |
87 | seq = ntohl(th->seq); | |
88 | ||
89 | newcheck = ~csum_fold((__force __wsum)((__force u32)th->check + | |
90 | (__force u32)delta)); | |
91 | ||
92 | do { | |
93 | th->fin = th->psh = 0; | |
94 | th->check = newcheck; | |
95 | ||
96 | if (skb->ip_summed != CHECKSUM_PARTIAL) | |
97 | th->check = | |
98 | csum_fold(csum_partial(skb_transport_header(skb), | |
99 | thlen, skb->csum)); | |
100 | ||
101 | seq += mss; | |
102 | if (copy_destructor) { | |
103 | skb->destructor = gso_skb->destructor; | |
104 | skb->sk = gso_skb->sk; | |
105 | /* {tcp|sock}_wfree() use exact truesize accounting : | |
106 | * sum(skb->truesize) MUST be exactly be gso_skb->truesize | |
107 | * So we account mss bytes of 'true size' for each segment. | |
108 | * The last segment will contain the remaining. | |
109 | */ | |
110 | skb->truesize = mss; | |
111 | gso_skb->truesize -= mss; | |
112 | } | |
113 | skb = skb->next; | |
114 | th = tcp_hdr(skb); | |
115 | ||
116 | th->seq = htonl(seq); | |
117 | th->cwr = 0; | |
118 | } while (skb->next); | |
119 | ||
120 | /* Following permits TCP Small Queues to work well with GSO : | |
121 | * The callback to TCP stack will be called at the time last frag | |
122 | * is freed at TX completion, and not right now when gso_skb | |
123 | * is freed by GSO engine | |
124 | */ | |
125 | if (copy_destructor) { | |
126 | swap(gso_skb->sk, skb->sk); | |
127 | swap(gso_skb->destructor, skb->destructor); | |
128 | swap(gso_skb->truesize, skb->truesize); | |
129 | } | |
130 | ||
131 | delta = htonl(oldlen + (skb_tail_pointer(skb) - | |
132 | skb_transport_header(skb)) + | |
133 | skb->data_len); | |
134 | th->check = ~csum_fold((__force __wsum)((__force u32)th->check + | |
135 | (__force u32)delta)); | |
136 | if (skb->ip_summed != CHECKSUM_PARTIAL) | |
137 | th->check = csum_fold(csum_partial(skb_transport_header(skb), | |
138 | thlen, skb->csum)); | |
139 | out: | |
140 | return segs; | |
141 | } | |
142 | EXPORT_SYMBOL(tcp_tso_segment); | |
143 | ||
144 | struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb) | |
145 | { | |
146 | struct sk_buff **pp = NULL; | |
147 | struct sk_buff *p; | |
148 | struct tcphdr *th; | |
149 | struct tcphdr *th2; | |
150 | unsigned int len; | |
151 | unsigned int thlen; | |
152 | __be32 flags; | |
153 | unsigned int mss = 1; | |
154 | unsigned int hlen; | |
155 | unsigned int off; | |
156 | int flush = 1; | |
157 | int i; | |
158 | ||
159 | off = skb_gro_offset(skb); | |
160 | hlen = off + sizeof(*th); | |
161 | th = skb_gro_header_fast(skb, off); | |
162 | if (skb_gro_header_hard(skb, hlen)) { | |
163 | th = skb_gro_header_slow(skb, hlen, off); | |
164 | if (unlikely(!th)) | |
165 | goto out; | |
166 | } | |
167 | ||
168 | thlen = th->doff * 4; | |
169 | if (thlen < sizeof(*th)) | |
170 | goto out; | |
171 | ||
172 | hlen = off + thlen; | |
173 | if (skb_gro_header_hard(skb, hlen)) { | |
174 | th = skb_gro_header_slow(skb, hlen, off); | |
175 | if (unlikely(!th)) | |
176 | goto out; | |
177 | } | |
178 | ||
179 | skb_gro_pull(skb, thlen); | |
180 | ||
181 | len = skb_gro_len(skb); | |
182 | flags = tcp_flag_word(th); | |
183 | ||
184 | for (; (p = *head); head = &p->next) { | |
185 | if (!NAPI_GRO_CB(p)->same_flow) | |
186 | continue; | |
187 | ||
188 | th2 = tcp_hdr(p); | |
189 | ||
190 | if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { | |
191 | NAPI_GRO_CB(p)->same_flow = 0; | |
192 | continue; | |
193 | } | |
194 | ||
195 | goto found; | |
196 | } | |
197 | ||
198 | goto out_check_final; | |
199 | ||
200 | found: | |
201 | flush = NAPI_GRO_CB(p)->flush; | |
202 | flush |= (__force int)(flags & TCP_FLAG_CWR); | |
203 | flush |= (__force int)((flags ^ tcp_flag_word(th2)) & | |
204 | ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); | |
205 | flush |= (__force int)(th->ack_seq ^ th2->ack_seq); | |
206 | for (i = sizeof(*th); i < thlen; i += 4) | |
207 | flush |= *(u32 *)((u8 *)th + i) ^ | |
208 | *(u32 *)((u8 *)th2 + i); | |
209 | ||
210 | mss = tcp_skb_mss(p); | |
211 | ||
212 | flush |= (len - 1) >= mss; | |
213 | flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); | |
214 | ||
215 | if (flush || skb_gro_receive(head, skb)) { | |
216 | mss = 1; | |
217 | goto out_check_final; | |
218 | } | |
219 | ||
220 | p = *head; | |
221 | th2 = tcp_hdr(p); | |
222 | tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); | |
223 | ||
224 | out_check_final: | |
225 | flush = len < mss; | |
226 | flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | | |
227 | TCP_FLAG_RST | TCP_FLAG_SYN | | |
228 | TCP_FLAG_FIN)); | |
229 | ||
230 | if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) | |
231 | pp = head; | |
232 | ||
233 | out: | |
234 | NAPI_GRO_CB(skb)->flush |= flush; | |
235 | ||
236 | return pp; | |
237 | } | |
238 | EXPORT_SYMBOL(tcp_gro_receive); | |
239 | ||
240 | int tcp_gro_complete(struct sk_buff *skb) | |
241 | { | |
242 | struct tcphdr *th = tcp_hdr(skb); | |
243 | ||
244 | skb->csum_start = skb_transport_header(skb) - skb->head; | |
245 | skb->csum_offset = offsetof(struct tcphdr, check); | |
246 | skb->ip_summed = CHECKSUM_PARTIAL; | |
247 | ||
248 | skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; | |
249 | ||
250 | if (th->cwr) | |
251 | skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; | |
252 | ||
253 | return 0; | |
254 | } | |
255 | EXPORT_SYMBOL(tcp_gro_complete); | |
256 | ||
257 | static int tcp_v4_gso_send_check(struct sk_buff *skb) | |
258 | { | |
259 | const struct iphdr *iph; | |
260 | struct tcphdr *th; | |
261 | ||
262 | if (!pskb_may_pull(skb, sizeof(*th))) | |
263 | return -EINVAL; | |
264 | ||
265 | iph = ip_hdr(skb); | |
266 | th = tcp_hdr(skb); | |
267 | ||
268 | th->check = 0; | |
269 | skb->ip_summed = CHECKSUM_PARTIAL; | |
270 | __tcp_v4_send_check(skb, iph->saddr, iph->daddr); | |
271 | return 0; | |
272 | } | |
273 | ||
274 | static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb) | |
275 | { | |
276 | const struct iphdr *iph = skb_gro_network_header(skb); | |
277 | __wsum wsum; | |
278 | __sum16 sum; | |
279 | ||
280 | switch (skb->ip_summed) { | |
281 | case CHECKSUM_COMPLETE: | |
282 | if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr, | |
283 | skb->csum)) { | |
284 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
285 | break; | |
286 | } | |
287 | flush: | |
288 | NAPI_GRO_CB(skb)->flush = 1; | |
289 | return NULL; | |
290 | ||
291 | case CHECKSUM_NONE: | |
292 | wsum = csum_tcpudp_nofold(iph->saddr, iph->daddr, | |
293 | skb_gro_len(skb), IPPROTO_TCP, 0); | |
294 | sum = csum_fold(skb_checksum(skb, | |
295 | skb_gro_offset(skb), | |
296 | skb_gro_len(skb), | |
297 | wsum)); | |
298 | if (sum) | |
299 | goto flush; | |
300 | ||
301 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
302 | break; | |
303 | } | |
304 | ||
305 | return tcp_gro_receive(head, skb); | |
306 | } | |
307 | ||
308 | static int tcp4_gro_complete(struct sk_buff *skb) | |
309 | { | |
310 | const struct iphdr *iph = ip_hdr(skb); | |
311 | struct tcphdr *th = tcp_hdr(skb); | |
312 | ||
313 | th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb), | |
314 | iph->saddr, iph->daddr, 0); | |
315 | skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4; | |
316 | ||
317 | return tcp_gro_complete(skb); | |
318 | } | |
319 | ||
320 | static const struct net_offload tcpv4_offload = { | |
321 | .callbacks = { | |
322 | .gso_send_check = tcp_v4_gso_send_check, | |
323 | .gso_segment = tcp_tso_segment, | |
324 | .gro_receive = tcp4_gro_receive, | |
325 | .gro_complete = tcp4_gro_complete, | |
326 | }, | |
327 | }; | |
328 | ||
329 | int __init tcpv4_offload_init(void) | |
330 | { | |
331 | return inet_add_offload(&tcpv4_offload, IPPROTO_TCP); | |
332 | } |