| /* |
| * IPv6 library code, needed by static components when full IPv6 support is |
| * not configured or static. |
| */ |
| #include <linux/export.h> |
| #include <net/ipv6.h> |
| |
| /* |
| * find out if nexthdr is a well-known extension header or a protocol |
| */ |
| |
| bool ipv6_ext_hdr(u8 nexthdr) |
| { |
| /* |
| * find out if nexthdr is an extension header or a protocol |
| */ |
| return (nexthdr == NEXTHDR_HOP) || |
| (nexthdr == NEXTHDR_ROUTING) || |
| (nexthdr == NEXTHDR_FRAGMENT) || |
| (nexthdr == NEXTHDR_AUTH) || |
| (nexthdr == NEXTHDR_NONE) || |
| (nexthdr == NEXTHDR_DEST); |
| } |
| EXPORT_SYMBOL(ipv6_ext_hdr); |
| |
| /* |
| * Skip any extension headers. This is used by the ICMP module. |
| * |
| * Note that strictly speaking this conflicts with RFC 2460 4.0: |
| * ...The contents and semantics of each extension header determine whether |
| * or not to proceed to the next header. Therefore, extension headers must |
| * be processed strictly in the order they appear in the packet; a |
| * receiver must not, for example, scan through a packet looking for a |
| * particular kind of extension header and process that header prior to |
| * processing all preceding ones. |
| * |
| * We do exactly this. This is a protocol bug. We can't decide after a |
| * seeing an unknown discard-with-error flavour TLV option if it's a |
| * ICMP error message or not (errors should never be send in reply to |
| * ICMP error messages). |
| * |
| * But I see no other way to do this. This might need to be reexamined |
| * when Linux implements ESP (and maybe AUTH) headers. |
| * --AK |
| * |
| * This function parses (probably truncated) exthdr set "hdr". |
| * "nexthdrp" initially points to some place, |
| * where type of the first header can be found. |
| * |
| * It skips all well-known exthdrs, and returns pointer to the start |
| * of unparsable area i.e. the first header with unknown type. |
| * If it is not NULL *nexthdr is updated by type/protocol of this header. |
| * |
| * NOTES: - if packet terminated with NEXTHDR_NONE it returns NULL. |
| * - it may return pointer pointing beyond end of packet, |
| * if the last recognized header is truncated in the middle. |
| * - if packet is truncated, so that all parsed headers are skipped, |
| * it returns NULL. |
| * - First fragment header is skipped, not-first ones |
| * are considered as unparsable. |
| * - Reports the offset field of the final fragment header so it is |
| * possible to tell whether this is a first fragment, later fragment, |
| * or not fragmented. |
| * - ESP is unparsable for now and considered like |
| * normal payload protocol. |
| * - Note also special handling of AUTH header. Thanks to IPsec wizards. |
| * |
| * --ANK (980726) |
| */ |
| |
| int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp, |
| __be16 *frag_offp) |
| { |
| u8 nexthdr = *nexthdrp; |
| |
| *frag_offp = 0; |
| |
| while (ipv6_ext_hdr(nexthdr)) { |
| struct ipv6_opt_hdr _hdr, *hp; |
| int hdrlen; |
| |
| if (nexthdr == NEXTHDR_NONE) |
| return -1; |
| hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr); |
| if (!hp) |
| return -1; |
| if (nexthdr == NEXTHDR_FRAGMENT) { |
| __be16 _frag_off, *fp; |
| fp = skb_header_pointer(skb, |
| start+offsetof(struct frag_hdr, |
| frag_off), |
| sizeof(_frag_off), |
| &_frag_off); |
| if (!fp) |
| return -1; |
| |
| *frag_offp = *fp; |
| if (ntohs(*frag_offp) & ~0x7) |
| break; |
| hdrlen = 8; |
| } else if (nexthdr == NEXTHDR_AUTH) |
| hdrlen = ipv6_authlen(hp); |
| else |
| hdrlen = ipv6_optlen(hp); |
| |
| nexthdr = hp->nexthdr; |
| start += hdrlen; |
| } |
| |
| *nexthdrp = nexthdr; |
| return start; |
| } |
| EXPORT_SYMBOL(ipv6_skip_exthdr); |
| |
| int ipv6_find_tlv(const struct sk_buff *skb, int offset, int type) |
| { |
| const unsigned char *nh = skb_network_header(skb); |
| int packet_len = skb_tail_pointer(skb) - skb_network_header(skb); |
| struct ipv6_opt_hdr *hdr; |
| int len; |
| |
| if (offset + 2 > packet_len) |
| goto bad; |
| hdr = (struct ipv6_opt_hdr *)(nh + offset); |
| len = ((hdr->hdrlen + 1) << 3); |
| |
| if (offset + len > packet_len) |
| goto bad; |
| |
| offset += 2; |
| len -= 2; |
| |
| while (len > 0) { |
| int opttype = nh[offset]; |
| int optlen; |
| |
| if (opttype == type) |
| return offset; |
| |
| switch (opttype) { |
| case IPV6_TLV_PAD1: |
| optlen = 1; |
| break; |
| default: |
| optlen = nh[offset + 1] + 2; |
| if (optlen > len) |
| goto bad; |
| break; |
| } |
| offset += optlen; |
| len -= optlen; |
| } |
| /* not_found */ |
| bad: |
| return -1; |
| } |
| EXPORT_SYMBOL_GPL(ipv6_find_tlv); |
| |
| /* |
| * find the offset to specified header or the protocol number of last header |
| * if target < 0. "last header" is transport protocol header, ESP, or |
| * "No next header". |
| * |
| * Note that *offset is used as input/output parameter. an if it is not zero, |
| * then it must be a valid offset to an inner IPv6 header. This can be used |
| * to explore inner IPv6 header, eg. ICMPv6 error messages. |
| * |
| * If target header is found, its offset is set in *offset and return protocol |
| * number. Otherwise, return -1. |
| * |
| * If the first fragment doesn't contain the final protocol header or |
| * NEXTHDR_NONE it is considered invalid. |
| * |
| * Note that non-1st fragment is special case that "the protocol number |
| * of last header" is "next header" field in Fragment header. In this case, |
| * *offset is meaningless and fragment offset is stored in *fragoff if fragoff |
| * isn't NULL. |
| * |
| * if flags is not NULL and it's a fragment, then the frag flag |
| * IP6_FH_F_FRAG will be set. If it's an AH header, the |
| * IP6_FH_F_AUTH flag is set and target < 0, then this function will |
| * stop at the AH header. If IP6_FH_F_SKIP_RH flag was passed, then this |
| * function will skip all those routing headers, where segements_left was 0. |
| */ |
| int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset, |
| int target, unsigned short *fragoff, int *flags) |
| { |
| unsigned int start = skb_network_offset(skb) + sizeof(struct ipv6hdr); |
| u8 nexthdr = ipv6_hdr(skb)->nexthdr; |
| bool found; |
| |
| if (fragoff) |
| *fragoff = 0; |
| |
| if (*offset) { |
| struct ipv6hdr _ip6, *ip6; |
| |
| ip6 = skb_header_pointer(skb, *offset, sizeof(_ip6), &_ip6); |
| if (!ip6 || (ip6->version != 6)) { |
| printk(KERN_ERR "IPv6 header not found\n"); |
| return -EBADMSG; |
| } |
| start = *offset + sizeof(struct ipv6hdr); |
| nexthdr = ip6->nexthdr; |
| } |
| |
| do { |
| struct ipv6_opt_hdr _hdr, *hp; |
| unsigned int hdrlen; |
| found = (nexthdr == target); |
| |
| if ((!ipv6_ext_hdr(nexthdr)) || nexthdr == NEXTHDR_NONE) { |
| if (target < 0 || found) |
| break; |
| return -ENOENT; |
| } |
| |
| hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr); |
| if (!hp) |
| return -EBADMSG; |
| |
| if (nexthdr == NEXTHDR_ROUTING) { |
| struct ipv6_rt_hdr _rh, *rh; |
| |
| rh = skb_header_pointer(skb, start, sizeof(_rh), |
| &_rh); |
| if (!rh) |
| return -EBADMSG; |
| |
| if (flags && (*flags & IP6_FH_F_SKIP_RH) && |
| rh->segments_left == 0) |
| found = false; |
| } |
| |
| if (nexthdr == NEXTHDR_FRAGMENT) { |
| unsigned short _frag_off; |
| __be16 *fp; |
| |
| if (flags) /* Indicate that this is a fragment */ |
| *flags |= IP6_FH_F_FRAG; |
| fp = skb_header_pointer(skb, |
| start+offsetof(struct frag_hdr, |
| frag_off), |
| sizeof(_frag_off), |
| &_frag_off); |
| if (!fp) |
| return -EBADMSG; |
| |
| _frag_off = ntohs(*fp) & ~0x7; |
| if (_frag_off) { |
| if (target < 0 && |
| ((!ipv6_ext_hdr(hp->nexthdr)) || |
| hp->nexthdr == NEXTHDR_NONE)) { |
| if (fragoff) |
| *fragoff = _frag_off; |
| return hp->nexthdr; |
| } |
| if (!found) |
| return -ENOENT; |
| if (fragoff) |
| *fragoff = _frag_off; |
| break; |
| } |
| hdrlen = 8; |
| } else if (nexthdr == NEXTHDR_AUTH) { |
| if (flags && (*flags & IP6_FH_F_AUTH) && (target < 0)) |
| break; |
| hdrlen = (hp->hdrlen + 2) << 2; |
| } else |
| hdrlen = ipv6_optlen(hp); |
| |
| if (!found) { |
| nexthdr = hp->nexthdr; |
| start += hdrlen; |
| } |
| } while (!found); |
| |
| *offset = start; |
| return nexthdr; |
| } |
| EXPORT_SYMBOL(ipv6_find_hdr); |