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/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
  12 static 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
  28 static 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
  50 static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
  51                                         const struct virtio_net_hdr *hdr,
  52                                         bool little_endian)
  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         u64 ret, remainder, gso_size;
  60
  61         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
  62                 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
  63                 case VIRTIO_NET_HDR_GSO_TCPV4:
  64                         gso_type = SKB_GSO_TCPV4;
  65                         ip_proto = IPPROTO_TCP;
  66                         thlen = sizeof(struct tcphdr);
  67                         break;
  68                 case VIRTIO_NET_HDR_GSO_TCPV6:
  69                         gso_type = SKB_GSO_TCPV6;
  70                         ip_proto = IPPROTO_TCP;
  71                         thlen = sizeof(struct tcphdr);
  72                         nh_min_len = sizeof(struct ipv6hdr);
  73                         break;
  74                 case VIRTIO_NET_HDR_GSO_UDP:
  75                         gso_type = SKB_GSO_UDP;
  76                         ip_proto = IPPROTO_UDP;
  77                         thlen = sizeof(struct udphdr);
  78                         break;
  79                 case VIRTIO_NET_HDR_GSO_UDP_L4:
  80                         gso_type = SKB_GSO_UDP_L4;
  81                         ip_proto = IPPROTO_UDP;
  82                         thlen = sizeof(struct udphdr);
  83                         break;
  84                 default:
  85                         return -EINVAL;
  86                 }
  87
  88                 if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
  89                         gso_type |= SKB_GSO_TCP_ECN;
  90
  91                 if (hdr->gso_size == 0)
  92                         return -EINVAL;
  93         }
  94
  95         skb_reset_mac_header(skb);
  96
  97         if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
  98                 u32 start = __virtio16_to_cpu(little_endian, hdr->csum_start);
  99                 u32 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
 100                 u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16));
 101
 102                 if (hdr->gso_size) {
 103                         gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size);
 104                         ret = div64_u64_rem(skb->len, gso_size, &remainder);
 105                         if (!(ret && (hdr->gso_size > needed) &&
 106                                                 ((remainder > needed) || (remainder == 0)))) {
 107                                 return -EINVAL;
 108                         }
 109                         skb_shinfo(skb)->tx_flags |= SKBFL_SHARED_FRAG;
 110                 }
 111
 112                 if (!pskb_may_pull(skb, needed))
 113                         return -EINVAL;
 114
 115                 if (!skb_partial_csum_set(skb, start, off))
 116                         return -EINVAL;
 117
 118                 nh_min_len = max_t(u32, nh_min_len, skb_transport_offset(skb));
 119                 p_off = nh_min_len + thlen;
 120                 if (!pskb_may_pull(skb, p_off))
 121                         return -EINVAL;
 122         } else {
 123                 /* gso packets without NEEDS_CSUM do not set transport_offset.
 124                  * probe and drop if does not match one of the above types.
 125                  */
 126                 if (gso_type && skb->network_header) {
 127                         struct flow_keys_basic keys;
 128
 129                         if (!skb->protocol) {
 130                                 __be16 protocol = dev_parse_header_protocol(skb);
 131
 132                                 if (!protocol)
 133                                         virtio_net_hdr_set_proto(skb, hdr);
 134                                 else if (!virtio_net_hdr_match_proto(protocol, hdr->gso_type))
 135                                         return -EINVAL;
 136                                 else
 137                                         skb->protocol = protocol;
 138                         }
 139 retry:
 140                         if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
 141                                                               NULL, 0, 0, 0,
 142                                                               0)) {
 143                                 /* UFO does not specify ipv4 or 6: try both */
 144                                 if (gso_type & SKB_GSO_UDP &&
 145                                     skb->protocol == htons(ETH_P_IP)) {
 146                                         skb->protocol = htons(ETH_P_IPV6);
 147                                         goto retry;
 148                                 }
 149                                 return -EINVAL;
 150                         }
 151
 152                         p_off = keys.control.thoff + thlen;
 153                         if (!pskb_may_pull(skb, p_off) ||
 154                             keys.basic.ip_proto != ip_proto)
 155                                 return -EINVAL;
 156
 157                         skb_set_transport_header(skb, keys.control.thoff);
 158                 } else if (gso_type) {
 159                         p_off = nh_min_len + thlen;
 160                         if (!pskb_may_pull(skb, p_off))
 161                                 return -EINVAL;
 162                 }
 163         }
 164
 165         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 166                 u16 gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size);
 167                 unsigned int nh_off = p_off;
 168                 struct skb_shared_info *shinfo = skb_shinfo(skb);
 169
 170                 switch (gso_type & ~SKB_GSO_TCP_ECN) {
 171                 case SKB_GSO_UDP:
 172                         /* UFO may not include transport header in gso_size. */
 173                         nh_off -= thlen;
 174                         break;
 175                 case SKB_GSO_UDP_L4:
 176                         if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
 177                                 return -EINVAL;
 178                         if (skb->csum_offset != offsetof(struct udphdr, check))
 179                                 return -EINVAL;
 180                         if (skb->len - p_off > gso_size * UDP_MAX_SEGMENTS)
 181                                 return -EINVAL;
 182                         if (gso_type != SKB_GSO_UDP_L4)
 183                                 return -EINVAL;
 184                         break;
 185                 }
 186
 187                 /* Kernel has a special handling for GSO_BY_FRAGS. */
 188                 if (gso_size == GSO_BY_FRAGS)
 189                         return -EINVAL;
 190
 191                 /* Too small packets are not really GSO ones. */
 192                 if (skb->len - nh_off > gso_size) {
 193                         shinfo->gso_size = gso_size;
 194                         shinfo->gso_type = gso_type;
 195
 196                         /* Header must be checked, and gso_segs computed. */
 197                         shinfo->gso_type |= SKB_GSO_DODGY;
 198                         shinfo->gso_segs = 0;
 199                 }
 200         }
 201
 202         return 0;
 203 }
 204
 205 static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
 206                                           struct virtio_net_hdr *hdr,
 207                                           bool little_endian,
 208                                           bool has_data_valid,
 209                                           int vlan_hlen)
 210 {
 211         memset(hdr, 0, sizeof(*hdr));   /* no info leak */
 212
 213         if (skb_is_gso(skb)) {
 214                 struct skb_shared_info *sinfo = skb_shinfo(skb);
 215
 216                 /* This is a hint as to how much should be linear. */
 217                 hdr->hdr_len = __cpu_to_virtio16(little_endian,
 218                                                  skb_headlen(skb));
 219                 hdr->gso_size = __cpu_to_virtio16(little_endian,
 220                                                   sinfo->gso_size);
 221                 if (sinfo->gso_type & SKB_GSO_TCPV4)
 222                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 223                 else if (sinfo->gso_type & SKB_GSO_TCPV6)
 224                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 225                 else if (sinfo->gso_type & SKB_GSO_UDP_L4)
 226                         hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP_L4;
 227                 else
 228                         return -EINVAL;
 229                 if (sinfo->gso_type & SKB_GSO_TCP_ECN)
 230                         hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
 231         } else
 232                 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
 233
 234         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 235                 hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 236                 hdr->csum_start = __cpu_to_virtio16(little_endian,
 237                         skb_checksum_start_offset(skb) + vlan_hlen);
 238                 hdr->csum_offset = __cpu_to_virtio16(little_endian,
 239                                 skb->csum_offset);
 240         } else if (has_data_valid &&
 241                    skb->ip_summed == CHECKSUM_UNNECESSARY) {
 242                 hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
 243         } /* else everything is zero */
 244
 245         return 0;
 246 }
 247
 248 #endif /* _LINUX_VIRTIO_NET_H */