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 <uapi/linux/tcp.h>
   7 #include <uapi/linux/udp.h>
   8 #include <uapi/linux/virtio_net.h>
   9
  10 static inline int virtio_net_hdr_set_proto(struct sk_buff *skb,
  11                                            const struct virtio_net_hdr *hdr)
  12 {
  13         switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
  14         case VIRTIO_NET_HDR_GSO_TCPV4:
  15         case VIRTIO_NET_HDR_GSO_UDP:
  16                 skb->protocol = cpu_to_be16(ETH_P_IP);
  17                 break;
  18         case VIRTIO_NET_HDR_GSO_TCPV6:
  19                 skb->protocol = cpu_to_be16(ETH_P_IPV6);
  20                 break;
  21         default:
  22                 return -EINVAL;
  23         }
  24
  25         return 0;
  26 }
  27
  28 static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
  29                                         const struct virtio_net_hdr *hdr,
  30                                         bool little_endian)
  31 {
  32         unsigned int gso_type = 0;
  33         unsigned int thlen = 0;
  34         unsigned int p_off = 0;
  35         unsigned int ip_proto;
  36
  37         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
  38                 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
  39                 case VIRTIO_NET_HDR_GSO_TCPV4:
  40                         gso_type = SKB_GSO_TCPV4;
  41                         ip_proto = IPPROTO_TCP;
  42                         thlen = sizeof(struct tcphdr);
  43                         break;
  44                 case VIRTIO_NET_HDR_GSO_TCPV6:
  45                         gso_type = SKB_GSO_TCPV6;
  46                         ip_proto = IPPROTO_TCP;
  47                         thlen = sizeof(struct tcphdr);
  48                         break;
  49                 case VIRTIO_NET_HDR_GSO_UDP:
  50                         gso_type = SKB_GSO_UDP;
  51                         ip_proto = IPPROTO_UDP;
  52                         thlen = sizeof(struct udphdr);
  53                         break;
  54                 default:
  55                         return -EINVAL;
  56                 }
  57
  58                 if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
  59                         gso_type |= SKB_GSO_TCP_ECN;
  60
  61                 if (hdr->gso_size == 0)
  62                         return -EINVAL;
  63         }
  64
  65         if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
  66                 u16 start = __virtio16_to_cpu(little_endian, hdr->csum_start);
  67                 u16 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
  68
  69                 if (!skb_partial_csum_set(skb, start, off))
  70                         return -EINVAL;
  71
  72                 p_off = skb_transport_offset(skb) + thlen;
  73                 if (p_off > skb_headlen(skb))
  74                         return -EINVAL;
  75         } else {
  76                 /* gso packets without NEEDS_CSUM do not set transport_offset.
  77                  * probe and drop if does not match one of the above types.
  78                  */
  79                 if (gso_type && skb->network_header) {
  80                         struct flow_keys_basic keys;
  81
  82                         if (!skb->protocol)
  83                                 virtio_net_hdr_set_proto(skb, hdr);
  84 retry:
  85                         if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
  86                                                               NULL, 0, 0, 0,
  87                                                               0)) {
  88                                 /* UFO does not specify ipv4 or 6: try both */
  89                                 if (gso_type & SKB_GSO_UDP &&
  90                                     skb->protocol == htons(ETH_P_IP)) {
  91                                         skb->protocol = htons(ETH_P_IPV6);
  92                                         goto retry;
  93                                 }
  94                                 return -EINVAL;
  95                         }
  96
  97                         p_off = keys.control.thoff + thlen;
  98                         if (p_off > skb_headlen(skb) ||
  99                             keys.basic.ip_proto != ip_proto)
 100                                 return -EINVAL;
 101
 102                         skb_set_transport_header(skb, keys.control.thoff);
 103                 } else if (gso_type) {
 104                         p_off = thlen;
 105                         if (p_off > skb_headlen(skb))
 106                                 return -EINVAL;
 107                 }
 108         }
 109
 110         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 111                 u16 gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size);
 112                 struct skb_shared_info *shinfo = skb_shinfo(skb);
 113
 114                 /* Too small packets are not really GSO ones. */
 115                 if (skb->len - p_off > gso_size) {
 116                         shinfo->gso_size = gso_size;
 117                         shinfo->gso_type = gso_type;
 118
 119                         /* Header must be checked, and gso_segs computed. */
 120                         shinfo->gso_type |= SKB_GSO_DODGY;
 121                         shinfo->gso_segs = 0;
 122                 }
 123         }
 124
 125         return 0;
 126 }
 127
 128 static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
 129                                           struct virtio_net_hdr *hdr,
 130                                           bool little_endian,
 131                                           bool has_data_valid,
 132                                           int vlan_hlen)
 133 {
 134         memset(hdr, 0, sizeof(*hdr));   /* no info leak */
 135
 136         if (skb_is_gso(skb)) {
 137                 struct skb_shared_info *sinfo = skb_shinfo(skb);
 138
 139                 /* This is a hint as to how much should be linear. */
 140                 hdr->hdr_len = __cpu_to_virtio16(little_endian,
 141                                                  skb_headlen(skb));
 142                 hdr->gso_size = __cpu_to_virtio16(little_endian,
 143                                                   sinfo->gso_size);
 144                 if (sinfo->gso_type & SKB_GSO_TCPV4)
 145                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 146                 else if (sinfo->gso_type & SKB_GSO_TCPV6)
 147                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 148                 else
 149                         return -EINVAL;
 150                 if (sinfo->gso_type & SKB_GSO_TCP_ECN)
 151                         hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
 152         } else
 153                 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
 154
 155         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 156                 hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 157                 hdr->csum_start = __cpu_to_virtio16(little_endian,
 158                         skb_checksum_start_offset(skb) + vlan_hlen);
 159                 hdr->csum_offset = __cpu_to_virtio16(little_endian,
 160                                 skb->csum_offset);
 161         } else if (has_data_valid &&
 162                    skb->ip_summed == CHECKSUM_UNNECESSARY) {
 163                 hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
 164         } /* else everything is zero */
 165
 166         return 0;
 167 }
 168
 169 #endif /* _LINUX_VIRTIO_NET_H */