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/udp.h>
7#include <uapi/linux/tcp.h>
8#include <uapi/linux/virtio_net.h>
9
10static inline bool virtio_net_hdr_match_proto(__be16 protocol, __u8 gso_type)
11{
12 switch (gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
13 case VIRTIO_NET_HDR_GSO_TCPV4:
14 return protocol == cpu_to_be16(ETH_P_IP);
15 case VIRTIO_NET_HDR_GSO_TCPV6:
16 return protocol == cpu_to_be16(ETH_P_IPV6);
17 case VIRTIO_NET_HDR_GSO_UDP:
18 case VIRTIO_NET_HDR_GSO_UDP_L4:
19 return protocol == cpu_to_be16(ETH_P_IP) ||
20 protocol == cpu_to_be16(ETH_P_IPV6);
21 default:
22 return false;
23 }
24}
25
26static inline int virtio_net_hdr_set_proto(struct sk_buff *skb,
27 const struct virtio_net_hdr *hdr)
28{
29 if (skb->protocol)
30 return 0;
31
32 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
33 case VIRTIO_NET_HDR_GSO_TCPV4:
34 case VIRTIO_NET_HDR_GSO_UDP:
35 case VIRTIO_NET_HDR_GSO_UDP_L4:
36 skb->protocol = cpu_to_be16(ETH_P_IP);
37 break;
38 case VIRTIO_NET_HDR_GSO_TCPV6:
39 skb->protocol = cpu_to_be16(ETH_P_IPV6);
40 break;
41 default:
42 return -EINVAL;
43 }
44
45 return 0;
46}
47
48static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
49 const struct virtio_net_hdr *hdr,
50 bool little_endian)
51{
52 unsigned int gso_type = 0;
53 unsigned int thlen = 0;
54 unsigned int p_off = 0;
55 unsigned int ip_proto;
56
57 if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
58 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
59 case VIRTIO_NET_HDR_GSO_TCPV4:
60 gso_type = SKB_GSO_TCPV4;
61 ip_proto = IPPROTO_TCP;
62 thlen = sizeof(struct tcphdr);
63 break;
64 case VIRTIO_NET_HDR_GSO_TCPV6:
65 gso_type = SKB_GSO_TCPV6;
66 ip_proto = IPPROTO_TCP;
67 thlen = sizeof(struct tcphdr);
68 break;
69 case VIRTIO_NET_HDR_GSO_UDP:
70 gso_type = SKB_GSO_UDP;
71 ip_proto = IPPROTO_UDP;
72 thlen = sizeof(struct udphdr);
73 break;
74 case VIRTIO_NET_HDR_GSO_UDP_L4:
75 gso_type = SKB_GSO_UDP_L4;
76 ip_proto = IPPROTO_UDP;
77 thlen = sizeof(struct udphdr);
78 break;
79 default:
80 return -EINVAL;
81 }
82
83 if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
84 gso_type |= SKB_GSO_TCP_ECN;
85
86 if (hdr->gso_size == 0)
87 return -EINVAL;
88 }
89
90 skb_reset_mac_header(skb);
91
92 if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
93 u32 start = __virtio16_to_cpu(little_endian, val: hdr->csum_start);
94 u32 off = __virtio16_to_cpu(little_endian, val: hdr->csum_offset);
95 u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16));
96
97 if (!pskb_may_pull(skb, len: needed))
98 return -EINVAL;
99
100 if (!skb_partial_csum_set(skb, start, off))
101 return -EINVAL;
102
103 p_off = skb_transport_offset(skb) + thlen;
104 if (!pskb_may_pull(skb, len: p_off))
105 return -EINVAL;
106 } else {
107 /* gso packets without NEEDS_CSUM do not set transport_offset.
108 * probe and drop if does not match one of the above types.
109 */
110 if (gso_type && skb->network_header) {
111 struct flow_keys_basic keys;
112
113 if (!skb->protocol) {
114 __be16 protocol = dev_parse_header_protocol(skb);
115
116 if (!protocol)
117 virtio_net_hdr_set_proto(skb, hdr);
118 else if (!virtio_net_hdr_match_proto(protocol, gso_type: hdr->gso_type))
119 return -EINVAL;
120 else
121 skb->protocol = protocol;
122 }
123retry:
124 if (!skb_flow_dissect_flow_keys_basic(NULL, skb, flow: &keys,
125 NULL, proto: 0, nhoff: 0, hlen: 0,
126 flags: 0)) {
127 /* UFO does not specify ipv4 or 6: try both */
128 if (gso_type & SKB_GSO_UDP &&
129 skb->protocol == htons(ETH_P_IP)) {
130 skb->protocol = htons(ETH_P_IPV6);
131 goto retry;
132 }
133 return -EINVAL;
134 }
135
136 p_off = keys.control.thoff + thlen;
137 if (!pskb_may_pull(skb, len: p_off) ||
138 keys.basic.ip_proto != ip_proto)
139 return -EINVAL;
140
141 skb_set_transport_header(skb, offset: keys.control.thoff);
142 } else if (gso_type) {
143 p_off = thlen;
144 if (!pskb_may_pull(skb, len: p_off))
145 return -EINVAL;
146 }
147 }
148
149 if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
150 u16 gso_size = __virtio16_to_cpu(little_endian, val: hdr->gso_size);
151 unsigned int nh_off = p_off;
152 struct skb_shared_info *shinfo = skb_shinfo(skb);
153
154 switch (gso_type & ~SKB_GSO_TCP_ECN) {
155 case SKB_GSO_UDP:
156 /* UFO may not include transport header in gso_size. */
157 nh_off -= thlen;
158 break;
159 case SKB_GSO_UDP_L4:
160 if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
161 return -EINVAL;
162 if (skb->csum_offset != offsetof(struct udphdr, check))
163 return -EINVAL;
164 if (skb->len - p_off > gso_size * UDP_MAX_SEGMENTS)
165 return -EINVAL;
166 if (gso_type != SKB_GSO_UDP_L4)
167 return -EINVAL;
168 break;
169 }
170
171 /* Kernel has a special handling for GSO_BY_FRAGS. */
172 if (gso_size == GSO_BY_FRAGS)
173 return -EINVAL;
174
175 /* Too small packets are not really GSO ones. */
176 if (skb->len - nh_off > gso_size) {
177 shinfo->gso_size = gso_size;
178 shinfo->gso_type = gso_type;
179
180 /* Header must be checked, and gso_segs computed. */
181 shinfo->gso_type |= SKB_GSO_DODGY;
182 shinfo->gso_segs = 0;
183 }
184 }
185
186 return 0;
187}
188
189static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
190 struct virtio_net_hdr *hdr,
191 bool little_endian,
192 bool has_data_valid,
193 int vlan_hlen)
194{
195 memset(hdr, 0, sizeof(*hdr)); /* no info leak */
196
197 if (skb_is_gso(skb)) {
198 struct skb_shared_info *sinfo = skb_shinfo(skb);
199
200 /* This is a hint as to how much should be linear. */
201 hdr->hdr_len = __cpu_to_virtio16(little_endian,
202 val: skb_headlen(skb));
203 hdr->gso_size = __cpu_to_virtio16(little_endian,
204 val: sinfo->gso_size);
205 if (sinfo->gso_type & SKB_GSO_TCPV4)
206 hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
207 else if (sinfo->gso_type & SKB_GSO_TCPV6)
208 hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
209 else if (sinfo->gso_type & SKB_GSO_UDP_L4)
210 hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP_L4;
211 else
212 return -EINVAL;
213 if (sinfo->gso_type & SKB_GSO_TCP_ECN)
214 hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
215 } else
216 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
217
218 if (skb->ip_summed == CHECKSUM_PARTIAL) {
219 hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
220 hdr->csum_start = __cpu_to_virtio16(little_endian,
221 val: skb_checksum_start_offset(skb) + vlan_hlen);
222 hdr->csum_offset = __cpu_to_virtio16(little_endian,
223 val: skb->csum_offset);
224 } else if (has_data_valid &&
225 skb->ip_summed == CHECKSUM_UNNECESSARY) {
226 hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
227 } /* else everything is zero */
228
229 return 0;
230}
231
232#endif /* _LINUX_VIRTIO_NET_H */
233

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