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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_VIRTIO_NET_H
3#define _LINUX_VIRTIO_NET_H
4
5#include <linux/if_vlan.h>
6#include <linux/ip.h>
7#include <linux/ipv6.h>
8#include <linux/udp.h>
9#include <uapi/linux/tcp.h>
10#include <uapi/linux/virtio_net.h>
11
12static inline bool virtio_net_hdr_match_proto(__be16 protocol, __u8 gso_type)
13{
14 switch (gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
15 case VIRTIO_NET_HDR_GSO_TCPV4:
16 return protocol == cpu_to_be16(ETH_P_IP);
17 case VIRTIO_NET_HDR_GSO_TCPV6:
18 return protocol == cpu_to_be16(ETH_P_IPV6);
19 case VIRTIO_NET_HDR_GSO_UDP:
20 case VIRTIO_NET_HDR_GSO_UDP_L4:
21 return protocol == cpu_to_be16(ETH_P_IP) ||
22 protocol == cpu_to_be16(ETH_P_IPV6);
23 default:
24 return false;
25 }
26}
27
28static inline int virtio_net_hdr_set_proto(struct sk_buff *skb,
29 const struct virtio_net_hdr *hdr)
30{
31 if (skb->protocol)
32 return 0;
33
34 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
35 case VIRTIO_NET_HDR_GSO_TCPV4:
36 case VIRTIO_NET_HDR_GSO_UDP:
37 case VIRTIO_NET_HDR_GSO_UDP_L4:
38 skb->protocol = cpu_to_be16(ETH_P_IP);
39 break;
40 case VIRTIO_NET_HDR_GSO_TCPV6:
41 skb->protocol = cpu_to_be16(ETH_P_IPV6);
42 break;
43 default:
44 return -EINVAL;
45 }
46
47 return 0;
48}
49
50static inline int __virtio_net_hdr_to_skb(struct sk_buff *skb,
51 const struct virtio_net_hdr *hdr,
52 bool little_endian, u8 hdr_gso_type)
53{
54 unsigned int nh_min_len = sizeof(struct iphdr);
55 unsigned int gso_type = 0;
56 unsigned int thlen = 0;
57 unsigned int p_off = 0;
58 unsigned int ip_proto;
59
60 if (hdr_gso_type != VIRTIO_NET_HDR_GSO_NONE) {
61 switch (hdr_gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
62 case VIRTIO_NET_HDR_GSO_TCPV4:
63 gso_type = SKB_GSO_TCPV4;
64 ip_proto = IPPROTO_TCP;
65 thlen = sizeof(struct tcphdr);
66 break;
67 case VIRTIO_NET_HDR_GSO_TCPV6:
68 gso_type = SKB_GSO_TCPV6;
69 ip_proto = IPPROTO_TCP;
70 thlen = sizeof(struct tcphdr);
71 nh_min_len = sizeof(struct ipv6hdr);
72 break;
73 case VIRTIO_NET_HDR_GSO_UDP:
74 gso_type = SKB_GSO_UDP;
75 ip_proto = IPPROTO_UDP;
76 thlen = sizeof(struct udphdr);
77 break;
78 case VIRTIO_NET_HDR_GSO_UDP_L4:
79 gso_type = SKB_GSO_UDP_L4;
80 ip_proto = IPPROTO_UDP;
81 thlen = sizeof(struct udphdr);
82 break;
83 default:
84 return -EINVAL;
85 }
86
87 if (hdr_gso_type & VIRTIO_NET_HDR_GSO_ECN)
88 gso_type |= SKB_GSO_TCP_ECN;
89
90 if (hdr->gso_size == 0)
91 return -EINVAL;
92 }
93
94 skb_reset_mac_header(skb);
95
96 if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
97 u32 start = __virtio16_to_cpu(little_endian, val: hdr->csum_start);
98 u32 off = __virtio16_to_cpu(little_endian, val: hdr->csum_offset);
99 u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16));
100
101 if (!pskb_may_pull(skb, len: needed))
102 return -EINVAL;
103
104 if (!skb_partial_csum_set(skb, start, off))
105 return -EINVAL;
106 if (skb_transport_offset(skb) < nh_min_len)
107 return -EINVAL;
108
109 nh_min_len = skb_transport_offset(skb);
110 p_off = nh_min_len + thlen;
111 if (!pskb_may_pull(skb, len: p_off))
112 return -EINVAL;
113 } else {
114 /* gso packets without NEEDS_CSUM do not set transport_offset.
115 * probe and drop if does not match one of the above types.
116 */
117 if (gso_type && skb->network_header) {
118 struct flow_keys_basic keys;
119
120 if (!skb->protocol) {
121 __be16 protocol = dev_parse_header_protocol(skb);
122
123 if (!protocol)
124 virtio_net_hdr_set_proto(skb, hdr);
125 else if (!virtio_net_hdr_match_proto(protocol,
126 gso_type: hdr_gso_type))
127 return -EINVAL;
128 else
129 skb->protocol = protocol;
130 }
131retry:
132 if (!skb_flow_dissect_flow_keys_basic(NULL, skb, flow: &keys,
133 NULL, proto: 0, nhoff: 0, hlen: 0,
134 flags: 0)) {
135 /* UFO does not specify ipv4 or 6: try both */
136 if (gso_type & SKB_GSO_UDP &&
137 skb->protocol == htons(ETH_P_IP)) {
138 skb->protocol = htons(ETH_P_IPV6);
139 goto retry;
140 }
141 return -EINVAL;
142 }
143
144 p_off = keys.control.thoff + thlen;
145 if (!pskb_may_pull(skb, len: p_off) ||
146 keys.basic.ip_proto != ip_proto)
147 return -EINVAL;
148
149 skb_set_transport_header(skb, offset: keys.control.thoff);
150 } else if (gso_type) {
151 p_off = nh_min_len + thlen;
152 if (!pskb_may_pull(skb, len: p_off))
153 return -EINVAL;
154 }
155 }
156
157 if (hdr_gso_type != VIRTIO_NET_HDR_GSO_NONE) {
158 u16 gso_size = __virtio16_to_cpu(little_endian, val: hdr->gso_size);
159 unsigned int nh_off = p_off;
160 struct skb_shared_info *shinfo = skb_shinfo(skb);
161
162 switch (gso_type & ~SKB_GSO_TCP_ECN) {
163 case SKB_GSO_UDP:
164 /* UFO may not include transport header in gso_size. */
165 nh_off -= thlen;
166 break;
167 case SKB_GSO_UDP_L4:
168 if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
169 return -EINVAL;
170 if (skb->csum_offset != offsetof(struct udphdr, check))
171 return -EINVAL;
172 if (skb->len - p_off > gso_size * UDP_MAX_SEGMENTS)
173 return -EINVAL;
174 if (gso_type != SKB_GSO_UDP_L4)
175 return -EINVAL;
176 break;
177 case SKB_GSO_TCPV4:
178 case SKB_GSO_TCPV6:
179 if (skb->ip_summed == CHECKSUM_PARTIAL &&
180 skb->csum_offset != offsetof(struct tcphdr, check))
181 return -EINVAL;
182 break;
183 }
184
185 /* Kernel has a special handling for GSO_BY_FRAGS. */
186 if (gso_size == GSO_BY_FRAGS)
187 return -EINVAL;
188
189 /* Too small packets are not really GSO ones. */
190 if (skb->len - nh_off > gso_size) {
191 shinfo->gso_size = gso_size;
192 shinfo->gso_type = gso_type;
193
194 /* Header must be checked, and gso_segs computed. */
195 shinfo->gso_type |= SKB_GSO_DODGY;
196 shinfo->gso_segs = 0;
197 }
198 }
199
200 return 0;
201}
202
203static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
204 const struct virtio_net_hdr *hdr,
205 bool little_endian)
206{
207 return __virtio_net_hdr_to_skb(skb, hdr, little_endian, hdr_gso_type: hdr->gso_type);
208}
209
210static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
211 struct virtio_net_hdr *hdr,
212 bool little_endian,
213 bool has_data_valid,
214 int vlan_hlen)
215{
216 memset(hdr, 0, sizeof(*hdr)); /* no info leak */
217
218 if (skb_is_gso(skb)) {
219 struct skb_shared_info *sinfo = skb_shinfo(skb);
220
221 /* This is a hint as to how much should be linear. */
222 hdr->hdr_len = __cpu_to_virtio16(little_endian,
223 val: skb_headlen(skb));
224 hdr->gso_size = __cpu_to_virtio16(little_endian,
225 val: sinfo->gso_size);
226 if (sinfo->gso_type & SKB_GSO_TCPV4)
227 hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
228 else if (sinfo->gso_type & SKB_GSO_TCPV6)
229 hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
230 else if (sinfo->gso_type & SKB_GSO_UDP_L4)
231 hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP_L4;
232 else
233 return -EINVAL;
234 if (sinfo->gso_type & SKB_GSO_TCP_ECN)
235 hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
236 } else
237 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
238
239 if (skb->ip_summed == CHECKSUM_PARTIAL) {
240 hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
241 hdr->csum_start = __cpu_to_virtio16(little_endian,
242 val: skb_checksum_start_offset(skb) + vlan_hlen);
243 hdr->csum_offset = __cpu_to_virtio16(little_endian,
244 val: skb->csum_offset);
245 } else if (has_data_valid &&
246 skb->ip_summed == CHECKSUM_UNNECESSARY) {
247 hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
248 } /* else everything is zero */
249
250 return 0;
251}
252
253static inline unsigned int virtio_l3min(bool is_ipv6)
254{
255 return is_ipv6 ? sizeof(struct ipv6hdr) : sizeof(struct iphdr);
256}
257
258static inline int
259virtio_net_hdr_tnl_to_skb(struct sk_buff *skb,
260 const struct virtio_net_hdr_v1_hash_tunnel *vhdr,
261 bool tnl_hdr_negotiated,
262 bool tnl_csum_negotiated,
263 bool little_endian)
264{
265 const struct virtio_net_hdr *hdr = (const struct virtio_net_hdr *)vhdr;
266 unsigned int inner_nh, outer_th, inner_th;
267 unsigned int inner_l3min, outer_l3min;
268 u8 gso_inner_type, gso_tunnel_type;
269 bool outer_isv6, inner_isv6;
270 int ret;
271
272 gso_tunnel_type = hdr->gso_type & VIRTIO_NET_HDR_GSO_UDP_TUNNEL;
273 if (!gso_tunnel_type)
274 return virtio_net_hdr_to_skb(skb, hdr, little_endian);
275
276 /* Tunnel not supported/negotiated, but the hdr asks for it. */
277 if (!tnl_hdr_negotiated)
278 return -EINVAL;
279
280 /* Either ipv4 or ipv6. */
281 if (gso_tunnel_type == VIRTIO_NET_HDR_GSO_UDP_TUNNEL)
282 return -EINVAL;
283
284 /* The UDP tunnel must carry a GSO packet, but no UFO. */
285 gso_inner_type = hdr->gso_type & ~(VIRTIO_NET_HDR_GSO_ECN |
286 VIRTIO_NET_HDR_GSO_UDP_TUNNEL);
287 if (!gso_inner_type || gso_inner_type == VIRTIO_NET_HDR_GSO_UDP)
288 return -EINVAL;
289
290 /* Rely on csum being present. */
291 if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
292 return -EINVAL;
293
294 /* Validate offsets. */
295 outer_isv6 = gso_tunnel_type & VIRTIO_NET_HDR_GSO_UDP_TUNNEL_IPV6;
296 inner_isv6 = gso_inner_type == VIRTIO_NET_HDR_GSO_TCPV6;
297 inner_l3min = virtio_l3min(is_ipv6: inner_isv6);
298 outer_l3min = ETH_HLEN + virtio_l3min(is_ipv6: outer_isv6);
299
300 inner_th = __virtio16_to_cpu(little_endian, val: hdr->csum_start);
301 inner_nh = le16_to_cpu(vhdr->inner_nh_offset);
302 outer_th = le16_to_cpu(vhdr->outer_th_offset);
303 if (outer_th < outer_l3min ||
304 inner_nh < outer_th + sizeof(struct udphdr) ||
305 inner_th < inner_nh + inner_l3min)
306 return -EINVAL;
307
308 /* Let the basic parsing deal with plain GSO features. */
309 ret = __virtio_net_hdr_to_skb(skb, hdr, little_endian: true,
310 hdr_gso_type: hdr->gso_type & ~gso_tunnel_type);
311 if (ret)
312 return ret;
313
314 /* In case of USO, the inner protocol is still unknown and
315 * `inner_isv6` is just a guess, additional parsing is needed.
316 * The previous validation ensures that accessing an ipv4 inner
317 * network header is safe.
318 */
319 if (gso_inner_type == VIRTIO_NET_HDR_GSO_UDP_L4) {
320 struct iphdr *iphdr = (struct iphdr *)(skb->data + inner_nh);
321
322 inner_isv6 = iphdr->version == 6;
323 inner_l3min = virtio_l3min(is_ipv6: inner_isv6);
324 if (inner_th < inner_nh + inner_l3min)
325 return -EINVAL;
326 }
327
328 skb_set_inner_protocol(skb, protocol: inner_isv6 ? htons(ETH_P_IPV6) :
329 htons(ETH_P_IP));
330 if (hdr->flags & VIRTIO_NET_HDR_F_UDP_TUNNEL_CSUM) {
331 if (!tnl_csum_negotiated)
332 return -EINVAL;
333
334 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
335 } else {
336 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
337 }
338
339 skb->inner_transport_header = inner_th + skb_headroom(skb);
340 skb->inner_network_header = inner_nh + skb_headroom(skb);
341 skb->inner_mac_header = inner_nh + skb_headroom(skb);
342 skb->transport_header = outer_th + skb_headroom(skb);
343 skb->encapsulation = 1;
344 return 0;
345}
346
347/* Checksum-related fields validation for the driver */
348static inline int virtio_net_handle_csum_offload(struct sk_buff *skb,
349 struct virtio_net_hdr *hdr,
350 bool tnl_csum_negotiated)
351{
352 if (!(hdr->gso_type & VIRTIO_NET_HDR_GSO_UDP_TUNNEL)) {
353 if (!(hdr->flags & VIRTIO_NET_HDR_F_DATA_VALID))
354 return 0;
355
356 skb->ip_summed = CHECKSUM_UNNECESSARY;
357 if (!(hdr->flags & VIRTIO_NET_HDR_F_UDP_TUNNEL_CSUM))
358 return 0;
359
360 /* tunnel csum packets are invalid when the related
361 * feature has not been negotiated
362 */
363 if (!tnl_csum_negotiated)
364 return -EINVAL;
365 skb->csum_level = 1;
366 return 0;
367 }
368
369 /* DATA_VALID is mutually exclusive with NEEDS_CSUM, and GSO
370 * over UDP tunnel requires the latter
371 */
372 if (hdr->flags & VIRTIO_NET_HDR_F_DATA_VALID)
373 return -EINVAL;
374 return 0;
375}
376
377/*
378 * vlan_hlen always refers to the outermost MAC header. That also
379 * means it refers to the only MAC header, if the packet does not carry
380 * any encapsulation.
381 */
382static inline int
383virtio_net_hdr_tnl_from_skb(const struct sk_buff *skb,
384 struct virtio_net_hdr_v1_hash_tunnel *vhdr,
385 bool tnl_hdr_negotiated,
386 bool little_endian,
387 int vlan_hlen,
388 bool has_data_valid)
389{
390 struct virtio_net_hdr *hdr = (struct virtio_net_hdr *)vhdr;
391 unsigned int inner_nh, outer_th;
392 int tnl_gso_type;
393 int ret;
394
395 tnl_gso_type = skb_shinfo(skb)->gso_type & (SKB_GSO_UDP_TUNNEL |
396 SKB_GSO_UDP_TUNNEL_CSUM);
397 if (!tnl_gso_type)
398 return virtio_net_hdr_from_skb(skb, hdr, little_endian,
399 has_data_valid, vlan_hlen);
400
401 /* Tunnel support not negotiated but skb ask for it. */
402 if (!tnl_hdr_negotiated)
403 return -EINVAL;
404
405 vhdr->hash_hdr.hash_value_lo = 0;
406 vhdr->hash_hdr.hash_value_hi = 0;
407 vhdr->hash_hdr.hash_report = 0;
408 vhdr->hash_hdr.padding = 0;
409
410 /* Let the basic parsing deal with plain GSO features. */
411 skb_shinfo(skb)->gso_type &= ~tnl_gso_type;
412 ret = virtio_net_hdr_from_skb(skb, hdr, little_endian: true, has_data_valid: false, vlan_hlen);
413 skb_shinfo(skb)->gso_type |= tnl_gso_type;
414 if (ret)
415 return ret;
416
417 if (skb->protocol == htons(ETH_P_IPV6))
418 hdr->gso_type |= VIRTIO_NET_HDR_GSO_UDP_TUNNEL_IPV6;
419 else
420 hdr->gso_type |= VIRTIO_NET_HDR_GSO_UDP_TUNNEL_IPV4;
421
422 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM)
423 hdr->flags |= VIRTIO_NET_HDR_F_UDP_TUNNEL_CSUM;
424
425 inner_nh = skb->inner_network_header - skb_headroom(skb);
426 outer_th = skb->transport_header - skb_headroom(skb);
427 vhdr->inner_nh_offset = cpu_to_le16(inner_nh);
428 vhdr->outer_th_offset = cpu_to_le16(outer_th);
429 return 0;
430}
431
432#endif /* _LINUX_VIRTIO_NET_H */
433

source code of linux/include/linux/virtio_net.h