include/linux/virtio_net.h

   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
  10 static 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
  26 static 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
  48 static 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, hdr->csum_start);
  94                 u32 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
  95                 u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16));
  96
  97                 if (!pskb_may_pull(skb, 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, 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, hdr->gso_type))
 119                                         return -EINVAL;
 120                                 else
 121                                         skb->protocol = protocol;
 122                         }
 123 retry:
 124                         if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
 125                                                               NULL, 0, 0, 0,
 126                                                               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, p_off) ||
 138                             keys.basic.ip_proto != ip_proto)
 139                                 return -EINVAL;
 140
 141                         skb_set_transport_header(skb, keys.control.thoff);
 142                 } else if (gso_type) {
 143                         p_off = thlen;
 144                         if (!pskb_may_pull(skb, 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, 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
 189 static 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                                                  skb_headlen(skb));
 203                 hdr->gso_size = __cpu_to_virtio16(little_endian,
 204                                                   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                         skb_checksum_start_offset(skb) + vlan_hlen);
 222                 hdr->csum_offset = __cpu_to_virtio16(little_endian,
 223                                 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 */