datapath/linux/compat/exthdrs_core.c

   1 #include <linux/ipv6.h>
   2 #include <linux/version.h>
   3 #include <net/ipv6.h>
   4
   5 #if LINUX_VERSION_CODE < KERNEL_VERSION(3,3,0)
   6 int rpl_ipv6_skip_exthdr(const struct sk_buff *skb, int start,
   7                          u8 *nexthdrp, __be16 *frag_offp)
   8 {
   9         u8 nexthdr = *nexthdrp;
  10
  11         *frag_offp = 0;
  12
  13         while (ipv6_ext_hdr(nexthdr)) {
  14                 struct ipv6_opt_hdr _hdr, *hp;
  15                 int hdrlen;
  16
  17                 if (nexthdr == NEXTHDR_NONE)
  18                         return -1;
  19                 hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
  20                 if (hp == NULL)
  21                         return -1;
  22                 if (nexthdr == NEXTHDR_FRAGMENT) {
  23                         __be16 _frag_off, *fp;
  24                         fp = skb_header_pointer(skb,
  25                                                 start+offsetof(struct frag_hdr,
  26                                                                frag_off),
  27                                                 sizeof(_frag_off),
  28                                                 &_frag_off);
  29                         if (fp == NULL)
  30                                 return -1;
  31
  32                         *frag_offp = *fp;
  33                         if (ntohs(*frag_offp) & ~0x7)
  34                                 break;
  35                         hdrlen = 8;
  36                 } else if (nexthdr == NEXTHDR_AUTH)
  37                         hdrlen = (hp->hdrlen+2)<<2;
  38                 else
  39                         hdrlen = ipv6_optlen(hp);
  40
  41                 nexthdr = hp->nexthdr;
  42                 start += hdrlen;
  43         }
  44
  45         *nexthdrp = nexthdr;
  46         return start;
  47 }
  48 #endif /* Kernel version < 3.3 */
  49
  50 /*
  51  * find the offset to specified header or the protocol number of last header
  52  * if target < 0. "last header" is transport protocol header, ESP, or
  53  * "No next header".
  54  *
  55  * Note that *offset is used as input/output parameter. an if it is not zero,
  56  * then it must be a valid offset to an inner IPv6 header. This can be used
  57  * to explore inner IPv6 header, eg. ICMPv6 error messages.
  58  *
  59  * If target header is found, its offset is set in *offset and return protocol
  60  * number. Otherwise, return -1.
  61  *
  62  * If the first fragment doesn't contain the final protocol header or
  63  * NEXTHDR_NONE it is considered invalid.
  64  *
  65  * Note that non-1st fragment is special case that "the protocol number
  66  * of last header" is "next header" field in Fragment header. In this case,
  67  * *offset is meaningless and fragment offset is stored in *fragoff if fragoff
  68  * isn't NULL.
  69  *
  70  * if flags is not NULL and it's a fragment, then the frag flag
  71  * OVS_IP6T_FH_F_FRAG will be set. If it's an AH header, the
  72  * OVS_IP6T_FH_F_AUTH flag is set and target < 0, then this function will
  73  * stop at the AH header. If OVS_IP6T_FH_F_SKIP_RH flag was passed, then this
  74  * function will skip all those routing headers, where segements_left was 0.
  75  */
  76 int rpl_ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
  77                   int target, unsigned short *fragoff, int *flags)
  78 {
  79         unsigned int start = skb_network_offset(skb) + sizeof(struct ipv6hdr);
  80         u8 nexthdr = ipv6_hdr(skb)->nexthdr;
  81         unsigned int len;
  82         bool found;
  83
  84         if (fragoff)
  85                 *fragoff = 0;
  86
  87         if (*offset) {
  88                 struct ipv6hdr _ip6, *ip6;
  89
  90                 ip6 = skb_header_pointer(skb, *offset, sizeof(_ip6), &_ip6);
  91                 if (!ip6 || (ip6->version != 6)) {
  92                         printk(KERN_ERR "IPv6 header not found\n");
  93                         return -EBADMSG;
  94                 }
  95                 start = *offset + sizeof(struct ipv6hdr);
  96                 nexthdr = ip6->nexthdr;
  97         }
  98         len = skb->len - start;
  99
 100         do {
 101                 struct ipv6_opt_hdr _hdr, *hp;
 102                 unsigned int hdrlen;
 103                 found = (nexthdr == target);
 104
 105                 if ((!ipv6_ext_hdr(nexthdr)) || nexthdr == NEXTHDR_NONE) {
 106                         if (target < 0)
 107                                 break;
 108                         return -ENOENT;
 109                 }
 110
 111                 hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
 112                 if (hp == NULL)
 113                         return -EBADMSG;
 114
 115                 if (nexthdr == NEXTHDR_ROUTING) {
 116                         struct ipv6_rt_hdr _rh, *rh;
 117
 118                         rh = skb_header_pointer(skb, start, sizeof(_rh),
 119                                                 &_rh);
 120                         if (rh == NULL)
 121                                 return -EBADMSG;
 122
 123                         if (flags && (*flags & OVS_IP6T_FH_F_SKIP_RH) &&
 124                             rh->segments_left == 0)
 125                                 found = false;
 126                 }
 127
 128                 if (nexthdr == NEXTHDR_FRAGMENT) {
 129                         unsigned short _frag_off;
 130                         __be16 *fp;
 131
 132                         if (flags)      /* Indicate that this is a fragment */
 133                                 *flags |= OVS_IP6T_FH_F_FRAG;
 134                         fp = skb_header_pointer(skb,
 135                                                 start+offsetof(struct frag_hdr,
 136                                                                frag_off),
 137                                                 sizeof(_frag_off),
 138                                                 &_frag_off);
 139                         if (fp == NULL)
 140                                 return -EBADMSG;
 141
 142                         _frag_off = ntohs(*fp) & ~0x7;
 143                         if (_frag_off) {
 144                                 if (target < 0 &&
 145                                     ((!ipv6_ext_hdr(hp->nexthdr)) ||
 146                                      hp->nexthdr == NEXTHDR_NONE)) {
 147                                         if (fragoff)
 148                                                 *fragoff = _frag_off;
 149                                         return hp->nexthdr;
 150                                 }
 151                                 return -ENOENT;
 152                         }
 153                         hdrlen = 8;
 154                 } else if (nexthdr == NEXTHDR_AUTH) {
 155                         if (flags && (*flags & OVS_IP6T_FH_F_AUTH) &&
 156                             (target < 0))
 157                                 break;
 158                         hdrlen = (hp->hdrlen + 2) << 2;
 159                 } else
 160                         hdrlen = ipv6_optlen(hp);
 161
 162                 if (!found) {
 163                         nexthdr = hp->nexthdr;
 164                         len -= hdrlen;
 165                         start += hdrlen;
 166                 }
 167         } while (!found);
 168
 169         *offset = start;
 170         return nexthdr;
 171 }