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