net/eth.c

   1 /*
   2  * QEMU network structures definitions and helper functions
   3  *
   4  * Copyright (c) 2012 Ravello Systems LTD (http://ravellosystems.com)
   5  *
   6  * Developed by Daynix Computing LTD (http://www.daynix.com)
   7  *
   8  * Authors:
   9  * Dmitry Fleytman <dmitry@daynix.com>
  10  * Tamir Shomer <tamirs@daynix.com>
  11  * Yan Vugenfirer <yan@daynix.com>
  12  *
  13  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  14  * See the COPYING file in the top-level directory.
  15  *
  16  */
  17
  18 #include "qemu/osdep.h"
  19 #include "net/eth.h"
  20 #include "net/checksum.h"
  21 #include "qemu-common.h"
  22 #include "net/tap.h"
  23
  24 void eth_setup_vlan_headers(struct eth_header *ehdr, uint16_t vlan_tag,
  25     bool *is_new)
  26 {
  27     struct vlan_header *vhdr = PKT_GET_VLAN_HDR(ehdr);
  28
  29     switch (be16_to_cpu(ehdr->h_proto)) {
  30     case ETH_P_VLAN:
  31     case ETH_P_DVLAN:
  32         /* vlan hdr exists */
  33         *is_new = false;
  34         break;
  35
  36     default:
  37         /* No VLAN header, put a new one */
  38         vhdr->h_proto = ehdr->h_proto;
  39         ehdr->h_proto = cpu_to_be16(ETH_P_VLAN);
  40         *is_new = true;
  41         break;
  42     }
  43     vhdr->h_tci = cpu_to_be16(vlan_tag);
  44 }
  45
  46 uint8_t
  47 eth_get_gso_type(uint16_t l3_proto, uint8_t *l3_hdr, uint8_t l4proto)
  48 {
  49     uint8_t ecn_state = 0;
  50
  51     if (l3_proto == ETH_P_IP) {
  52         struct ip_header *iphdr = (struct ip_header *) l3_hdr;
  53
  54         if (IP_HEADER_VERSION(iphdr) == IP_HEADER_VERSION_4) {
  55             if (IPTOS_ECN(iphdr->ip_tos) == IPTOS_ECN_CE) {
  56                 ecn_state = VIRTIO_NET_HDR_GSO_ECN;
  57             }
  58             if (l4proto == IP_PROTO_TCP) {
  59                 return VIRTIO_NET_HDR_GSO_TCPV4 | ecn_state;
  60             } else if (l4proto == IP_PROTO_UDP) {
  61                 return VIRTIO_NET_HDR_GSO_UDP | ecn_state;
  62             }
  63         }
  64     } else if (l3_proto == ETH_P_IPV6) {
  65         struct ip6_header *ip6hdr = (struct ip6_header *) l3_hdr;
  66
  67         if (IP6_ECN(ip6hdr->ip6_ecn_acc) == IP6_ECN_CE) {
  68             ecn_state = VIRTIO_NET_HDR_GSO_ECN;
  69         }
  70
  71         if (l4proto == IP_PROTO_TCP) {
  72             return VIRTIO_NET_HDR_GSO_TCPV6 | ecn_state;
  73         }
  74     }
  75
  76     /* Unsupported offload */
  77     g_assert_not_reached();
  78
  79     return VIRTIO_NET_HDR_GSO_NONE | ecn_state;
  80 }
  81
  82 void eth_get_protocols(const uint8_t *headers,
  83                        uint32_t hdr_length,
  84                        bool *isip4, bool *isip6,
  85                        bool *isudp, bool *istcp)
  86 {
  87     int proto;
  88     size_t l2hdr_len = eth_get_l2_hdr_length(headers);
  89     assert(hdr_length >= eth_get_l2_hdr_length(headers));
  90     *isip4 = *isip6 = *isudp = *istcp = false;
  91
  92     proto = eth_get_l3_proto(headers, l2hdr_len);
  93     if (proto == ETH_P_IP) {
  94         *isip4 = true;
  95
  96         struct ip_header *iphdr;
  97
  98         assert(hdr_length >=
  99             eth_get_l2_hdr_length(headers) + sizeof(struct ip_header));
 100
 101         iphdr = PKT_GET_IP_HDR(headers);
 102
 103         if (IP_HEADER_VERSION(iphdr) == IP_HEADER_VERSION_4) {
 104             if (iphdr->ip_p == IP_PROTO_TCP) {
 105                 *istcp = true;
 106             } else if (iphdr->ip_p == IP_PROTO_UDP) {
 107                 *isudp = true;
 108             }
 109         }
 110     } else if (proto == ETH_P_IPV6) {
 111         uint8_t l4proto;
 112         size_t full_ip6hdr_len;
 113
 114         struct iovec hdr_vec;
 115         hdr_vec.iov_base = (void *) headers;
 116         hdr_vec.iov_len = hdr_length;
 117
 118         *isip6 = true;
 119         if (eth_parse_ipv6_hdr(&hdr_vec, 1, l2hdr_len,
 120                               &l4proto, &full_ip6hdr_len)) {
 121             if (l4proto == IP_PROTO_TCP) {
 122                 *istcp = true;
 123             } else if (l4proto == IP_PROTO_UDP) {
 124                 *isudp = true;
 125             }
 126         }
 127     }
 128 }
 129
 130 void
 131 eth_setup_ip4_fragmentation(const void *l2hdr, size_t l2hdr_len,
 132                             void *l3hdr, size_t l3hdr_len,
 133                             size_t l3payload_len,
 134                             size_t frag_offset, bool more_frags)
 135 {
 136     if (eth_get_l3_proto(l2hdr, l2hdr_len) == ETH_P_IP) {
 137         uint16_t orig_flags;
 138         struct ip_header *iphdr = (struct ip_header *) l3hdr;
 139         uint16_t frag_off_units = frag_offset / IP_FRAG_UNIT_SIZE;
 140         uint16_t new_ip_off;
 141
 142         assert(frag_offset % IP_FRAG_UNIT_SIZE == 0);
 143         assert((frag_off_units & ~IP_OFFMASK) == 0);
 144
 145         orig_flags = be16_to_cpu(iphdr->ip_off) & ~(IP_OFFMASK|IP_MF);
 146         new_ip_off = frag_off_units | orig_flags  | (more_frags ? IP_MF : 0);
 147         iphdr->ip_off = cpu_to_be16(new_ip_off);
 148         iphdr->ip_len = cpu_to_be16(l3payload_len + l3hdr_len);
 149     }
 150 }
 151
 152 void
 153 eth_fix_ip4_checksum(void *l3hdr, size_t l3hdr_len)
 154 {
 155     struct ip_header *iphdr = (struct ip_header *) l3hdr;
 156     iphdr->ip_sum = 0;
 157     iphdr->ip_sum = cpu_to_be16(net_raw_checksum(l3hdr, l3hdr_len));
 158 }
 159
 160 uint32_t
 161 eth_calc_pseudo_hdr_csum(struct ip_header *iphdr, uint16_t csl)
 162 {
 163     struct ip_pseudo_header ipph;
 164     ipph.ip_src = iphdr->ip_src;
 165     ipph.ip_dst = iphdr->ip_dst;
 166     ipph.ip_payload = cpu_to_be16(csl);
 167     ipph.ip_proto = iphdr->ip_p;
 168     ipph.zeros = 0;
 169     return net_checksum_add(sizeof(ipph), (uint8_t *) &ipph);
 170 }
 171
 172 static bool
 173 eth_is_ip6_extension_header_type(uint8_t hdr_type)
 174 {
 175     switch (hdr_type) {
 176     case IP6_HOP_BY_HOP:
 177     case IP6_ROUTING:
 178     case IP6_FRAGMENT:
 179     case IP6_ESP:
 180     case IP6_AUTHENTICATION:
 181     case IP6_DESTINATON:
 182     case IP6_MOBILITY:
 183         return true;
 184     default:
 185         return false;
 186     }
 187 }
 188
 189 bool eth_parse_ipv6_hdr(struct iovec *pkt, int pkt_frags,
 190                         size_t ip6hdr_off, uint8_t *l4proto,
 191                         size_t *full_hdr_len)
 192 {
 193     struct ip6_header ip6_hdr;
 194     struct ip6_ext_hdr ext_hdr;
 195     size_t bytes_read;
 196
 197     bytes_read = iov_to_buf(pkt, pkt_frags, ip6hdr_off,
 198                             &ip6_hdr, sizeof(ip6_hdr));
 199     if (bytes_read < sizeof(ip6_hdr)) {
 200         return false;
 201     }
 202
 203     *full_hdr_len = sizeof(struct ip6_header);
 204
 205     if (!eth_is_ip6_extension_header_type(ip6_hdr.ip6_nxt)) {
 206         *l4proto = ip6_hdr.ip6_nxt;
 207         return true;
 208     }
 209
 210     do {
 211         bytes_read = iov_to_buf(pkt, pkt_frags, ip6hdr_off + *full_hdr_len,
 212                                 &ext_hdr, sizeof(ext_hdr));
 213         *full_hdr_len += (ext_hdr.ip6r_len + 1) * IP6_EXT_GRANULARITY;
 214     } while (eth_is_ip6_extension_header_type(ext_hdr.ip6r_nxt));
 215
 216     *l4proto = ext_hdr.ip6r_nxt;
 217     return true;
 218 }