diff options
Diffstat (limited to 'net/ipv6/netfilter/ip6t_ipv6header.c')
| -rw-r--r-- | net/ipv6/netfilter/ip6t_ipv6header.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/net/ipv6/netfilter/ip6t_ipv6header.c b/net/ipv6/netfilter/ip6t_ipv6header.c new file mode 100644 index 000000000..c52ff929c --- /dev/null +++ b/net/ipv6/netfilter/ip6t_ipv6header.c @@ -0,0 +1,153 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* ipv6header match - matches IPv6 packets based + on whether they contain certain headers */ + +/* Original idea: Brad Chapman + * Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */ + +/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> + */ + +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/ipv6.h> +#include <linux/types.h> +#include <net/checksum.h> +#include <net/ipv6.h> + +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter_ipv6.h> +#include <linux/netfilter_ipv6/ip6t_ipv6header.h> + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Xtables: IPv6 header types match"); +MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); + +static bool +ipv6header_mt6(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct ip6t_ipv6header_info *info = par->matchinfo; + unsigned int temp; + int len; + u8 nexthdr; + unsigned int ptr; + + /* Make sure this isn't an evil packet */ + + /* type of the 1st exthdr */ + nexthdr = ipv6_hdr(skb)->nexthdr; + /* pointer to the 1st exthdr */ + ptr = sizeof(struct ipv6hdr); + /* available length */ + len = skb->len - ptr; + temp = 0; + + while (nf_ip6_ext_hdr(nexthdr)) { + const struct ipv6_opt_hdr *hp; + struct ipv6_opt_hdr _hdr; + int hdrlen; + + /* No more exthdr -> evaluate */ + if (nexthdr == NEXTHDR_NONE) { + temp |= MASK_NONE; + break; + } + /* Is there enough space for the next ext header? */ + if (len < (int)sizeof(struct ipv6_opt_hdr)) + return false; + /* ESP -> evaluate */ + if (nexthdr == NEXTHDR_ESP) { + temp |= MASK_ESP; + break; + } + + hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr); + if (!hp) { + par->hotdrop = true; + return false; + } + + /* Calculate the header length */ + if (nexthdr == NEXTHDR_FRAGMENT) + hdrlen = 8; + else if (nexthdr == NEXTHDR_AUTH) + hdrlen = ipv6_authlen(hp); + else + hdrlen = ipv6_optlen(hp); + + /* set the flag */ + switch (nexthdr) { + case NEXTHDR_HOP: + temp |= MASK_HOPOPTS; + break; + case NEXTHDR_ROUTING: + temp |= MASK_ROUTING; + break; + case NEXTHDR_FRAGMENT: + temp |= MASK_FRAGMENT; + break; + case NEXTHDR_AUTH: + temp |= MASK_AH; + break; + case NEXTHDR_DEST: + temp |= MASK_DSTOPTS; + break; + default: + return false; + } + + nexthdr = hp->nexthdr; + len -= hdrlen; + ptr += hdrlen; + if (ptr > skb->len) + break; + } + + if (nexthdr != NEXTHDR_NONE && nexthdr != NEXTHDR_ESP) + temp |= MASK_PROTO; + + if (info->modeflag) + return !((temp ^ info->matchflags ^ info->invflags) + & info->matchflags); + else { + if (info->invflags) + return temp != info->matchflags; + else + return temp == info->matchflags; + } +} + +static int ipv6header_mt6_check(const struct xt_mtchk_param *par) +{ + const struct ip6t_ipv6header_info *info = par->matchinfo; + + /* invflags is 0 or 0xff in hard mode */ + if ((!info->modeflag) && info->invflags != 0x00 && + info->invflags != 0xFF) + return -EINVAL; + + return 0; +} + +static struct xt_match ipv6header_mt6_reg __read_mostly = { + .name = "ipv6header", + .family = NFPROTO_IPV6, + .match = ipv6header_mt6, + .matchsize = sizeof(struct ip6t_ipv6header_info), + .checkentry = ipv6header_mt6_check, + .destroy = NULL, + .me = THIS_MODULE, +}; + +static int __init ipv6header_mt6_init(void) +{ + return xt_register_match(&ipv6header_mt6_reg); +} + +static void __exit ipv6header_mt6_exit(void) +{ + xt_unregister_match(&ipv6header_mt6_reg); +} + +module_init(ipv6header_mt6_init); +module_exit(ipv6header_mt6_exit); |