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