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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * IPV4 GSO/GRO offload support
4 * Linux INET implementation
5 *
6 * GRE GSO support
7 */
8
9#include <linux/skbuff.h>
10#include <linux/init.h>
11#include <net/protocol.h>
12#include <net/gre.h>
13
14static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
15 netdev_features_t features)
16{
17 int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
18 bool need_csum, need_recompute_csum, gso_partial;
19 struct sk_buff *segs = ERR_PTR(-EINVAL);
20 u16 mac_offset = skb->mac_header;
21 __be16 protocol = skb->protocol;
22 u16 mac_len = skb->mac_len;
23 int gre_offset, outer_hlen;
24
25 if (!skb->encapsulation)
26 goto out;
27
28 if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
29 goto out;
30
31 if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
32 goto out;
33
34 /* setup inner skb. */
35 skb->encapsulation = 0;
36 SKB_GSO_CB(skb)->encap_level = 0;
37 __skb_pull(skb, tnl_hlen);
38 skb_reset_mac_header(skb);
39 skb_set_network_header(skb, skb_inner_network_offset(skb));
40 skb->mac_len = skb_inner_network_offset(skb);
41 skb->protocol = skb->inner_protocol;
42
43 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
44 need_recompute_csum = skb->csum_not_inet;
45 skb->encap_hdr_csum = need_csum;
46
47 features &= skb->dev->hw_enc_features;
48
49 /* segment inner packet. */
50 segs = skb_mac_gso_segment(skb, features);
51 if (IS_ERR_OR_NULL(segs)) {
52 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
53 mac_len);
54 goto out;
55 }
56
57 gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
58
59 outer_hlen = skb_tnl_header_len(skb);
60 gre_offset = outer_hlen - tnl_hlen;
61 skb = segs;
62 do {
63 struct gre_base_hdr *greh;
64 __sum16 *pcsum;
65
66 /* Set up inner headers if we are offloading inner checksum */
67 if (skb->ip_summed == CHECKSUM_PARTIAL) {
68 skb_reset_inner_headers(skb);
69 skb->encapsulation = 1;
70 }
71
72 skb->mac_len = mac_len;
73 skb->protocol = protocol;
74
75 __skb_push(skb, outer_hlen);
76 skb_reset_mac_header(skb);
77 skb_set_network_header(skb, mac_len);
78 skb_set_transport_header(skb, gre_offset);
79
80 if (!need_csum)
81 continue;
82
83 greh = (struct gre_base_hdr *)skb_transport_header(skb);
84 pcsum = (__sum16 *)(greh + 1);
85
86 if (gso_partial && skb_is_gso(skb)) {
87 unsigned int partial_adj;
88
89 /* Adjust checksum to account for the fact that
90 * the partial checksum is based on actual size
91 * whereas headers should be based on MSS size.
92 */
93 partial_adj = skb->len + skb_headroom(skb) -
94 SKB_GSO_CB(skb)->data_offset -
95 skb_shinfo(skb)->gso_size;
96 *pcsum = ~csum_fold((__force __wsum)htonl(partial_adj));
97 } else {
98 *pcsum = 0;
99 }
100
101 *(pcsum + 1) = 0;
102 if (need_recompute_csum && !skb_is_gso(skb)) {
103 __wsum csum;
104
105 csum = skb_checksum(skb, gre_offset,
106 skb->len - gre_offset, 0);
107 *pcsum = csum_fold(csum);
108 } else {
109 *pcsum = gso_make_checksum(skb, 0);
110 }
111 } while ((skb = skb->next));
112out:
113 return segs;
114}
115
116static struct sk_buff *gre_gro_receive(struct list_head *head,
117 struct sk_buff *skb)
118{
119 struct sk_buff *pp = NULL;
120 struct sk_buff *p;
121 const struct gre_base_hdr *greh;
122 unsigned int hlen, grehlen;
123 unsigned int off;
124 int flush = 1;
125 struct packet_offload *ptype;
126 __be16 type;
127
128 if (NAPI_GRO_CB(skb)->encap_mark)
129 goto out;
130
131 NAPI_GRO_CB(skb)->encap_mark = 1;
132
133 off = skb_gro_offset(skb);
134 hlen = off + sizeof(*greh);
135 greh = skb_gro_header_fast(skb, off);
136 if (skb_gro_header_hard(skb, hlen)) {
137 greh = skb_gro_header_slow(skb, hlen, off);
138 if (unlikely(!greh))
139 goto out;
140 }
141
142 /* Only support version 0 and K (key), C (csum) flags. Note that
143 * although the support for the S (seq#) flag can be added easily
144 * for GRO, this is problematic for GSO hence can not be enabled
145 * here because a GRO pkt may end up in the forwarding path, thus
146 * requiring GSO support to break it up correctly.
147 */
148 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
149 goto out;
150
151 /* We can only support GRE_CSUM if we can track the location of
152 * the GRE header. In the case of FOU/GUE we cannot because the
153 * outer UDP header displaces the GRE header leaving us in a state
154 * of limbo.
155 */
156 if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou)
157 goto out;
158
159 type = greh->protocol;
160
161 rcu_read_lock();
162 ptype = gro_find_receive_by_type(type);
163 if (!ptype)
164 goto out_unlock;
165
166 grehlen = GRE_HEADER_SECTION;
167
168 if (greh->flags & GRE_KEY)
169 grehlen += GRE_HEADER_SECTION;
170
171 if (greh->flags & GRE_CSUM)
172 grehlen += GRE_HEADER_SECTION;
173
174 hlen = off + grehlen;
175 if (skb_gro_header_hard(skb, hlen)) {
176 greh = skb_gro_header_slow(skb, hlen, off);
177 if (unlikely(!greh))
178 goto out_unlock;
179 }
180
181 /* Don't bother verifying checksum if we're going to flush anyway. */
182 if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
183 if (skb_gro_checksum_simple_validate(skb))
184 goto out_unlock;
185
186 skb_gro_checksum_try_convert(skb, IPPROTO_GRE,
187 null_compute_pseudo);
188 }
189
190 list_for_each_entry(p, head, list) {
191 const struct gre_base_hdr *greh2;
192
193 if (!NAPI_GRO_CB(p)->same_flow)
194 continue;
195
196 /* The following checks are needed to ensure only pkts
197 * from the same tunnel are considered for aggregation.
198 * The criteria for "the same tunnel" includes:
199 * 1) same version (we only support version 0 here)
200 * 2) same protocol (we only support ETH_P_IP for now)
201 * 3) same set of flags
202 * 4) same key if the key field is present.
203 */
204 greh2 = (struct gre_base_hdr *)(p->data + off);
205
206 if (greh2->flags != greh->flags ||
207 greh2->protocol != greh->protocol) {
208 NAPI_GRO_CB(p)->same_flow = 0;
209 continue;
210 }
211 if (greh->flags & GRE_KEY) {
212 /* compare keys */
213 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
214 NAPI_GRO_CB(p)->same_flow = 0;
215 continue;
216 }
217 }
218 }
219
220 skb_gro_pull(skb, grehlen);
221
222 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
223 skb_gro_postpull_rcsum(skb, greh, grehlen);
224
225 pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb);
226 flush = 0;
227
228out_unlock:
229 rcu_read_unlock();
230out:
231 skb_gro_flush_final(skb, pp, flush);
232
233 return pp;
234}
235
236static int gre_gro_complete(struct sk_buff *skb, int nhoff)
237{
238 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
239 struct packet_offload *ptype;
240 unsigned int grehlen = sizeof(*greh);
241 int err = -ENOENT;
242 __be16 type;
243
244 skb->encapsulation = 1;
245 skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
246
247 type = greh->protocol;
248 if (greh->flags & GRE_KEY)
249 grehlen += GRE_HEADER_SECTION;
250
251 if (greh->flags & GRE_CSUM)
252 grehlen += GRE_HEADER_SECTION;
253
254 rcu_read_lock();
255 ptype = gro_find_complete_by_type(type);
256 if (ptype)
257 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
258
259 rcu_read_unlock();
260
261 skb_set_inner_mac_header(skb, nhoff + grehlen);
262
263 return err;
264}
265
266static const struct net_offload gre_offload = {
267 .callbacks = {
268 .gso_segment = gre_gso_segment,
269 .gro_receive = gre_gro_receive,
270 .gro_complete = gre_gro_complete,
271 },
272};
273
274static int __init gre_offload_init(void)
275{
276 int err;
277
278 err = inet_add_offload(&gre_offload, IPPROTO_GRE);
279#if IS_ENABLED(CONFIG_IPV6)
280 if (err)
281 return err;
282
283 err = inet6_add_offload(&gre_offload, IPPROTO_GRE);
284 if (err)
285 inet_del_offload(&gre_offload, IPPROTO_GRE);
286#endif
287
288 return err;
289}
290device_initcall(gre_offload_init);
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 * GRE GSO support
11 */
12
13#include <linux/skbuff.h>
14#include <linux/init.h>
15#include <net/protocol.h>
16#include <net/gre.h>
17
18static int gre_gso_send_check(struct sk_buff *skb)
19{
20 if (!skb->encapsulation)
21 return -EINVAL;
22 return 0;
23}
24
25static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
26 netdev_features_t features)
27{
28 struct sk_buff *segs = ERR_PTR(-EINVAL);
29 netdev_features_t enc_features;
30 int ghl;
31 struct gre_base_hdr *greh;
32 u16 mac_offset = skb->mac_header;
33 int mac_len = skb->mac_len;
34 __be16 protocol = skb->protocol;
35 int tnl_hlen;
36 bool csum;
37
38 if (unlikely(skb_shinfo(skb)->gso_type &
39 ~(SKB_GSO_TCPV4 |
40 SKB_GSO_TCPV6 |
41 SKB_GSO_UDP |
42 SKB_GSO_DODGY |
43 SKB_GSO_TCP_ECN |
44 SKB_GSO_GRE |
45 SKB_GSO_IPIP)))
46 goto out;
47
48 if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
49 goto out;
50
51 greh = (struct gre_base_hdr *)skb_transport_header(skb);
52
53 ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
54 if (unlikely(ghl < sizeof(*greh)))
55 goto out;
56
57 csum = !!(greh->flags & GRE_CSUM);
58
59 if (unlikely(!pskb_may_pull(skb, ghl)))
60 goto out;
61
62 /* setup inner skb. */
63 skb->protocol = greh->protocol;
64 skb->encapsulation = 0;
65
66 __skb_pull(skb, ghl);
67 skb_reset_mac_header(skb);
68 skb_set_network_header(skb, skb_inner_network_offset(skb));
69 skb->mac_len = skb_inner_network_offset(skb);
70
71 /* segment inner packet. */
72 enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
73 segs = skb_mac_gso_segment(skb, enc_features);
74 if (!segs || IS_ERR(segs)) {
75 skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
76 goto out;
77 }
78
79 skb = segs;
80 tnl_hlen = skb_tnl_header_len(skb);
81 do {
82 __skb_push(skb, ghl);
83 if (csum) {
84 __be32 *pcsum;
85
86 if (skb_has_shared_frag(skb)) {
87 int err;
88
89 err = __skb_linearize(skb);
90 if (err) {
91 kfree_skb_list(segs);
92 segs = ERR_PTR(err);
93 goto out;
94 }
95 }
96
97 greh = (struct gre_base_hdr *)(skb->data);
98 pcsum = (__be32 *)(greh + 1);
99 *pcsum = 0;
100 *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
101 }
102 __skb_push(skb, tnl_hlen - ghl);
103
104 skb_reset_inner_headers(skb);
105 skb->encapsulation = 1;
106
107 skb_reset_mac_header(skb);
108 skb_set_network_header(skb, mac_len);
109 skb->mac_len = mac_len;
110 skb->protocol = protocol;
111 } while ((skb = skb->next));
112out:
113 return segs;
114}
115
116/* Compute the whole skb csum in s/w and store it, then verify GRO csum
117 * starting from gro_offset.
118 */
119static __sum16 gro_skb_checksum(struct sk_buff *skb)
120{
121 __sum16 sum;
122
123 skb->csum = skb_checksum(skb, 0, skb->len, 0);
124 NAPI_GRO_CB(skb)->csum = csum_sub(skb->csum,
125 csum_partial(skb->data, skb_gro_offset(skb), 0));
126 sum = csum_fold(NAPI_GRO_CB(skb)->csum);
127 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
128 if (unlikely(!sum))
129 netdev_rx_csum_fault(skb->dev);
130 } else
131 skb->ip_summed = CHECKSUM_COMPLETE;
132
133 return sum;
134}
135
136static struct sk_buff **gre_gro_receive(struct sk_buff **head,
137 struct sk_buff *skb)
138{
139 struct sk_buff **pp = NULL;
140 struct sk_buff *p;
141 const struct gre_base_hdr *greh;
142 unsigned int hlen, grehlen;
143 unsigned int off;
144 int flush = 1;
145 struct packet_offload *ptype;
146 __be16 type;
147
148 off = skb_gro_offset(skb);
149 hlen = off + sizeof(*greh);
150 greh = skb_gro_header_fast(skb, off);
151 if (skb_gro_header_hard(skb, hlen)) {
152 greh = skb_gro_header_slow(skb, hlen, off);
153 if (unlikely(!greh))
154 goto out;
155 }
156
157 /* Only support version 0 and K (key), C (csum) flags. Note that
158 * although the support for the S (seq#) flag can be added easily
159 * for GRO, this is problematic for GSO hence can not be enabled
160 * here because a GRO pkt may end up in the forwarding path, thus
161 * requiring GSO support to break it up correctly.
162 */
163 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
164 goto out;
165
166 type = greh->protocol;
167
168 rcu_read_lock();
169 ptype = gro_find_receive_by_type(type);
170 if (ptype == NULL)
171 goto out_unlock;
172
173 grehlen = GRE_HEADER_SECTION;
174
175 if (greh->flags & GRE_KEY)
176 grehlen += GRE_HEADER_SECTION;
177
178 if (greh->flags & GRE_CSUM)
179 grehlen += GRE_HEADER_SECTION;
180
181 hlen = off + grehlen;
182 if (skb_gro_header_hard(skb, hlen)) {
183 greh = skb_gro_header_slow(skb, hlen, off);
184 if (unlikely(!greh))
185 goto out_unlock;
186 }
187 if (greh->flags & GRE_CSUM) { /* Need to verify GRE csum first */
188 __sum16 csum = 0;
189
190 if (skb->ip_summed == CHECKSUM_COMPLETE)
191 csum = csum_fold(NAPI_GRO_CB(skb)->csum);
192 /* Don't trust csum error calculated/reported by h/w */
193 if (skb->ip_summed == CHECKSUM_NONE || csum != 0)
194 csum = gro_skb_checksum(skb);
195
196 /* GRE CSUM is the 1's complement of the 1's complement sum
197 * of the GRE hdr plus payload so it should add up to 0xffff
198 * (and 0 after csum_fold()) just like the IPv4 hdr csum.
199 */
200 if (csum)
201 goto out_unlock;
202 }
203 flush = 0;
204
205 for (p = *head; p; p = p->next) {
206 const struct gre_base_hdr *greh2;
207
208 if (!NAPI_GRO_CB(p)->same_flow)
209 continue;
210
211 /* The following checks are needed to ensure only pkts
212 * from the same tunnel are considered for aggregation.
213 * The criteria for "the same tunnel" includes:
214 * 1) same version (we only support version 0 here)
215 * 2) same protocol (we only support ETH_P_IP for now)
216 * 3) same set of flags
217 * 4) same key if the key field is present.
218 */
219 greh2 = (struct gre_base_hdr *)(p->data + off);
220
221 if (greh2->flags != greh->flags ||
222 greh2->protocol != greh->protocol) {
223 NAPI_GRO_CB(p)->same_flow = 0;
224 continue;
225 }
226 if (greh->flags & GRE_KEY) {
227 /* compare keys */
228 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
229 NAPI_GRO_CB(p)->same_flow = 0;
230 continue;
231 }
232 }
233 }
234
235 skb_gro_pull(skb, grehlen);
236
237 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
238 skb_gro_postpull_rcsum(skb, greh, grehlen);
239
240 pp = ptype->callbacks.gro_receive(head, skb);
241
242out_unlock:
243 rcu_read_unlock();
244out:
245 NAPI_GRO_CB(skb)->flush |= flush;
246
247 return pp;
248}
249
250static int gre_gro_complete(struct sk_buff *skb, int nhoff)
251{
252 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
253 struct packet_offload *ptype;
254 unsigned int grehlen = sizeof(*greh);
255 int err = -ENOENT;
256 __be16 type;
257
258 type = greh->protocol;
259 if (greh->flags & GRE_KEY)
260 grehlen += GRE_HEADER_SECTION;
261
262 if (greh->flags & GRE_CSUM)
263 grehlen += GRE_HEADER_SECTION;
264
265 rcu_read_lock();
266 ptype = gro_find_complete_by_type(type);
267 if (ptype != NULL)
268 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
269
270 rcu_read_unlock();
271 return err;
272}
273
274static const struct net_offload gre_offload = {
275 .callbacks = {
276 .gso_send_check = gre_gso_send_check,
277 .gso_segment = gre_gso_segment,
278 .gro_receive = gre_gro_receive,
279 .gro_complete = gre_gro_complete,
280 },
281};
282
283static int __init gre_offload_init(void)
284{
285 return inet_add_offload(&gre_offload, IPPROTO_GRE);
286}
287device_initcall(gre_offload_init);