From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Andr=C3=A9=20Fabian=20Silva=20Delgado?= Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- net/ipv6/exthdrs_core.c | 281 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 281 insertions(+) create mode 100644 net/ipv6/exthdrs_core.c (limited to 'net/ipv6/exthdrs_core.c') diff --git a/net/ipv6/exthdrs_core.c b/net/ipv6/exthdrs_core.c new file mode 100644 index 000000000..5c5d23e59 --- /dev/null +++ b/net/ipv6/exthdrs_core.c @@ -0,0 +1,281 @@ +/* + * IPv6 library code, needed by static components when full IPv6 support is + * not configured or static. + */ +#include +#include + +/* + * 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 = (hp->hdrlen+2)<<2; + else + hdrlen = ipv6_optlen(hp); + + nexthdr = hp->nexthdr; + start += hdrlen; + } + + *nexthdrp = nexthdr; + return start; +} +EXPORT_SYMBOL(ipv6_skip_exthdr); + +int ipv6_find_tlv(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; + unsigned int len; + 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; + } + len = skb->len - start; + + 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; + } + return -ENOENT; + } + 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; + len -= hdrlen; + start += hdrlen; + } + } while (!found); + + *offset = start; + return nexthdr; +} +EXPORT_SYMBOL(ipv6_find_hdr); + -- cgit v1.2.3