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/gso.h> |
13 | #include <net/tcp.h> |
14 | #include <net/protocol.h> |
15 | |
16 | static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq, |
17 | unsigned int seq, unsigned int mss) |
18 | { |
19 | while (skb) { |
20 | if (before(seq1: ts_seq, seq2: seq + mss)) { |
21 | skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP; |
22 | skb_shinfo(skb)->tskey = ts_seq; |
23 | return; |
24 | } |
25 | |
26 | skb = skb->next; |
27 | seq += mss; |
28 | } |
29 | } |
30 | |
31 | static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb, |
32 | netdev_features_t features) |
33 | { |
34 | if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)) |
35 | return ERR_PTR(error: -EINVAL); |
36 | |
37 | if (!pskb_may_pull(skb, len: sizeof(struct tcphdr))) |
38 | return ERR_PTR(error: -EINVAL); |
39 | |
40 | if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) { |
41 | const struct iphdr *iph = ip_hdr(skb); |
42 | struct tcphdr *th = tcp_hdr(skb); |
43 | |
44 | /* Set up checksum pseudo header, usually expect stack to |
45 | * have done this already. |
46 | */ |
47 | |
48 | th->check = 0; |
49 | skb->ip_summed = CHECKSUM_PARTIAL; |
50 | __tcp_v4_send_check(skb, saddr: iph->saddr, daddr: iph->daddr); |
51 | } |
52 | |
53 | return tcp_gso_segment(skb, features); |
54 | } |
55 | |
56 | struct sk_buff *tcp_gso_segment(struct sk_buff *skb, |
57 | netdev_features_t features) |
58 | { |
59 | struct sk_buff *segs = ERR_PTR(error: -EINVAL); |
60 | unsigned int sum_truesize = 0; |
61 | struct tcphdr *th; |
62 | unsigned int thlen; |
63 | unsigned int seq; |
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 | __wsum delta; |
70 | |
71 | th = tcp_hdr(skb); |
72 | thlen = th->doff * 4; |
73 | if (thlen < sizeof(*th)) |
74 | goto out; |
75 | |
76 | if (!pskb_may_pull(skb, len: thlen)) |
77 | goto out; |
78 | |
79 | oldlen = ~skb->len; |
80 | __skb_pull(skb, len: thlen); |
81 | |
82 | mss = skb_shinfo(skb)->gso_size; |
83 | if (unlikely(skb->len <= mss)) |
84 | goto out; |
85 | |
86 | if (skb_gso_ok(skb, features: features | NETIF_F_GSO_ROBUST)) { |
87 | /* Packet is from an untrusted source, reset gso_segs. */ |
88 | |
89 | skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); |
90 | |
91 | segs = NULL; |
92 | goto out; |
93 | } |
94 | |
95 | copy_destructor = gso_skb->destructor == tcp_wfree; |
96 | ooo_okay = gso_skb->ooo_okay; |
97 | /* All segments but the first should have ooo_okay cleared */ |
98 | skb->ooo_okay = 0; |
99 | |
100 | segs = skb_segment(skb, features); |
101 | if (IS_ERR(ptr: segs)) |
102 | goto out; |
103 | |
104 | /* Only first segment might have ooo_okay set */ |
105 | segs->ooo_okay = ooo_okay; |
106 | |
107 | /* GSO partial and frag_list segmentation only requires splitting |
108 | * the frame into an MSS multiple and possibly a remainder, both |
109 | * cases return a GSO skb. So update the mss now. |
110 | */ |
111 | if (skb_is_gso(skb: segs)) |
112 | mss *= skb_shinfo(segs)->gso_segs; |
113 | |
114 | delta = (__force __wsum)htonl(oldlen + thlen + mss); |
115 | |
116 | skb = segs; |
117 | th = tcp_hdr(skb); |
118 | seq = ntohl(th->seq); |
119 | |
120 | if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP)) |
121 | tcp_gso_tstamp(skb: segs, skb_shinfo(gso_skb)->tskey, seq, mss); |
122 | |
123 | newcheck = ~csum_fold(sum: csum_add(csum: csum_unfold(n: th->check), addend: 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, res: ~th->check); |
131 | else |
132 | th->check = gso_make_checksum(skb, res: ~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(i: delta, r: &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 = (__force __wsum)htonl(oldlen + |
169 | (skb_tail_pointer(skb) - |
170 | skb_transport_header(skb)) + |
171 | skb->data_len); |
172 | th->check = ~csum_fold(sum: csum_add(csum: csum_unfold(n: th->check), addend: delta)); |
173 | if (skb->ip_summed == CHECKSUM_PARTIAL) |
174 | gso_reset_checksum(skb, res: ~th->check); |
175 | else |
176 | th->check = gso_make_checksum(skb, res: ~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, offset: 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, offset: off); |
209 | if (unlikely(!th)) |
210 | goto out; |
211 | } |
212 | |
213 | skb_gro_pull(skb, len: 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(skb: 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(skb: 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 | void 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 | EXPORT_SYMBOL(tcp_gro_complete); |
316 | |
317 | INDIRECT_CALLABLE_SCOPE |
318 | struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb) |
319 | { |
320 | /* Don't bother verifying checksum if we're going to flush anyway. */ |
321 | if (!NAPI_GRO_CB(skb)->flush && |
322 | skb_gro_checksum_validate(skb, IPPROTO_TCP, |
323 | inet_gro_compute_pseudo)) { |
324 | NAPI_GRO_CB(skb)->flush = 1; |
325 | return NULL; |
326 | } |
327 | |
328 | return tcp_gro_receive(head, skb); |
329 | } |
330 | |
331 | INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff) |
332 | { |
333 | const struct iphdr *iph = ip_hdr(skb); |
334 | struct tcphdr *th = tcp_hdr(skb); |
335 | |
336 | th->check = ~tcp_v4_check(len: skb->len - thoff, saddr: iph->saddr, |
337 | daddr: iph->daddr, base: 0); |
338 | skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4; |
339 | |
340 | if (NAPI_GRO_CB(skb)->is_atomic) |
341 | skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID; |
342 | |
343 | tcp_gro_complete(skb); |
344 | return 0; |
345 | } |
346 | |
347 | static const struct net_offload tcpv4_offload = { |
348 | .callbacks = { |
349 | .gso_segment = tcp4_gso_segment, |
350 | .gro_receive = tcp4_gro_receive, |
351 | .gro_complete = tcp4_gro_complete, |
352 | }, |
353 | }; |
354 | |
355 | int __init tcpv4_offload_init(void) |
356 | { |
357 | return inet_add_offload(prot: &tcpv4_offload, IPPROTO_TCP); |
358 | } |
359 | |