udp_offload.c 3.7 KB

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  1. /*
  2. * IPV6 GSO/GRO offload support
  3. * Linux INET6 implementation
  4. *
  5. * This program is free software; you can redistribute it and/or
  6. * modify it under the terms of the GNU General Public License
  7. * as published by the Free Software Foundation; either version
  8. * 2 of the License, or (at your option) any later version.
  9. *
  10. * UDPv6 GSO support
  11. */
  12. #include <linux/skbuff.h>
  13. #include <net/protocol.h>
  14. #include <net/ipv6.h>
  15. #include <net/udp.h>
  16. #include <net/ip6_checksum.h>
  17. #include "ip6_offload.h"
  18. static int udp6_ufo_send_check(struct sk_buff *skb)
  19. {
  20. const struct ipv6hdr *ipv6h;
  21. struct udphdr *uh;
  22. if (!pskb_may_pull(skb, sizeof(*uh)))
  23. return -EINVAL;
  24. if (likely(!skb->encapsulation)) {
  25. ipv6h = ipv6_hdr(skb);
  26. uh = udp_hdr(skb);
  27. uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len,
  28. IPPROTO_UDP, 0);
  29. skb->csum_start = skb_transport_header(skb) - skb->head;
  30. skb->csum_offset = offsetof(struct udphdr, check);
  31. skb->ip_summed = CHECKSUM_PARTIAL;
  32. }
  33. return 0;
  34. }
  35. static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
  36. netdev_features_t features)
  37. {
  38. struct sk_buff *segs = ERR_PTR(-EINVAL);
  39. unsigned int mss;
  40. unsigned int unfrag_ip6hlen, unfrag_len;
  41. struct frag_hdr *fptr;
  42. u8 *packet_start, *prevhdr;
  43. u8 nexthdr;
  44. u8 frag_hdr_sz = sizeof(struct frag_hdr);
  45. int offset;
  46. __wsum csum;
  47. int tnl_hlen;
  48. mss = skb_shinfo(skb)->gso_size;
  49. if (unlikely(skb->len <= mss))
  50. goto out;
  51. if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
  52. /* Packet is from an untrusted source, reset gso_segs. */
  53. int type = skb_shinfo(skb)->gso_type;
  54. if (unlikely(type & ~(SKB_GSO_UDP |
  55. SKB_GSO_DODGY |
  56. SKB_GSO_UDP_TUNNEL |
  57. SKB_GSO_GRE |
  58. SKB_GSO_MPLS) ||
  59. !(type & (SKB_GSO_UDP))))
  60. goto out;
  61. skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
  62. segs = NULL;
  63. goto out;
  64. }
  65. if (skb->encapsulation && skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL)
  66. segs = skb_udp_tunnel_segment(skb, features);
  67. else {
  68. /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  69. * do checksum of UDP packets sent as multiple IP fragments.
  70. */
  71. offset = skb_checksum_start_offset(skb);
  72. csum = skb_checksum(skb, offset, skb->len - offset, 0);
  73. offset += skb->csum_offset;
  74. *(__sum16 *)(skb->data + offset) = csum_fold(csum);
  75. skb->ip_summed = CHECKSUM_NONE;
  76. /* Check if there is enough headroom to insert fragment header. */
  77. tnl_hlen = skb_tnl_header_len(skb);
  78. if (skb_headroom(skb) < (tnl_hlen + frag_hdr_sz)) {
  79. if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  80. goto out;
  81. }
  82. /* Find the unfragmentable header and shift it left by frag_hdr_sz
  83. * bytes to insert fragment header.
  84. */
  85. unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
  86. nexthdr = *prevhdr;
  87. *prevhdr = NEXTHDR_FRAGMENT;
  88. unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
  89. unfrag_ip6hlen + tnl_hlen;
  90. packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
  91. memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
  92. SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
  93. skb->mac_header -= frag_hdr_sz;
  94. skb->network_header -= frag_hdr_sz;
  95. fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
  96. fptr->nexthdr = nexthdr;
  97. fptr->reserved = 0;
  98. ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb));
  99. /* Fragment the skb. ipv6 header and the remaining fields of the
  100. * fragment header are updated in ipv6_gso_segment()
  101. */
  102. segs = skb_segment(skb, features);
  103. }
  104. out:
  105. return segs;
  106. }
  107. static const struct net_offload udpv6_offload = {
  108. .callbacks = {
  109. .gso_send_check = udp6_ufo_send_check,
  110. .gso_segment = udp6_ufo_fragment,
  111. },
  112. };
  113. int __init udp_offload_init(void)
  114. {
  115. return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
  116. }