diff options
Diffstat (limited to '')
-rw-r--r-- | net/ipv6/netfilter/ip6t_srh.c | 320 |
1 files changed, 320 insertions, 0 deletions
diff --git a/net/ipv6/netfilter/ip6t_srh.c b/net/ipv6/netfilter/ip6t_srh.c new file mode 100644 index 000000000..db0fd64d8 --- /dev/null +++ b/net/ipv6/netfilter/ip6t_srh.c @@ -0,0 +1,320 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Kernel module to match Segment Routing Header (SRH) parameters. */ + +/* Author: + * Ahmed Abdelsalam <amsalam20@gmail.com> + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/ipv6.h> +#include <linux/types.h> +#include <net/ipv6.h> +#include <net/seg6.h> + +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter_ipv6/ip6t_srh.h> +#include <linux/netfilter_ipv6/ip6_tables.h> + +/* Test a struct->mt_invflags and a boolean for inequality */ +#define NF_SRH_INVF(ptr, flag, boolean) \ + ((boolean) ^ !!((ptr)->mt_invflags & (flag))) + +static bool srh_mt6(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct ip6t_srh *srhinfo = par->matchinfo; + struct ipv6_sr_hdr *srh; + struct ipv6_sr_hdr _srh; + int hdrlen, srhoff = 0; + + if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, NULL) < 0) + return false; + srh = skb_header_pointer(skb, srhoff, sizeof(_srh), &_srh); + if (!srh) + return false; + + hdrlen = ipv6_optlen(srh); + if (skb->len - srhoff < hdrlen) + return false; + + if (srh->type != IPV6_SRCRT_TYPE_4) + return false; + + if (srh->segments_left > srh->first_segment) + return false; + + /* Next Header matching */ + if (srhinfo->mt_flags & IP6T_SRH_NEXTHDR) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_NEXTHDR, + !(srh->nexthdr == srhinfo->next_hdr))) + return false; + + /* Header Extension Length matching */ + if (srhinfo->mt_flags & IP6T_SRH_LEN_EQ) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_EQ, + !(srh->hdrlen == srhinfo->hdr_len))) + return false; + + if (srhinfo->mt_flags & IP6T_SRH_LEN_GT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_GT, + !(srh->hdrlen > srhinfo->hdr_len))) + return false; + + if (srhinfo->mt_flags & IP6T_SRH_LEN_LT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_LT, + !(srh->hdrlen < srhinfo->hdr_len))) + return false; + + /* Segments Left matching */ + if (srhinfo->mt_flags & IP6T_SRH_SEGS_EQ) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_EQ, + !(srh->segments_left == srhinfo->segs_left))) + return false; + + if (srhinfo->mt_flags & IP6T_SRH_SEGS_GT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_GT, + !(srh->segments_left > srhinfo->segs_left))) + return false; + + if (srhinfo->mt_flags & IP6T_SRH_SEGS_LT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_LT, + !(srh->segments_left < srhinfo->segs_left))) + return false; + + /** + * Last Entry matching + * Last_Entry field was introduced in revision 6 of the SRH draft. + * It was called First_Segment in the previous revision + */ + if (srhinfo->mt_flags & IP6T_SRH_LAST_EQ) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_EQ, + !(srh->first_segment == srhinfo->last_entry))) + return false; + + if (srhinfo->mt_flags & IP6T_SRH_LAST_GT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_GT, + !(srh->first_segment > srhinfo->last_entry))) + return false; + + if (srhinfo->mt_flags & IP6T_SRH_LAST_LT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_LT, + !(srh->first_segment < srhinfo->last_entry))) + return false; + + /** + * Tag matchig + * Tag field was introduced in revision 6 of the SRH draft. + */ + if (srhinfo->mt_flags & IP6T_SRH_TAG) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_TAG, + !(srh->tag == srhinfo->tag))) + return false; + return true; +} + +static bool srh1_mt6(const struct sk_buff *skb, struct xt_action_param *par) +{ + int hdrlen, psidoff, nsidoff, lsidoff, srhoff = 0; + const struct ip6t_srh1 *srhinfo = par->matchinfo; + struct in6_addr *psid, *nsid, *lsid; + struct in6_addr _psid, _nsid, _lsid; + struct ipv6_sr_hdr *srh; + struct ipv6_sr_hdr _srh; + + if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, NULL) < 0) + return false; + srh = skb_header_pointer(skb, srhoff, sizeof(_srh), &_srh); + if (!srh) + return false; + + hdrlen = ipv6_optlen(srh); + if (skb->len - srhoff < hdrlen) + return false; + + if (srh->type != IPV6_SRCRT_TYPE_4) + return false; + + if (srh->segments_left > srh->first_segment) + return false; + + /* Next Header matching */ + if (srhinfo->mt_flags & IP6T_SRH_NEXTHDR) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_NEXTHDR, + !(srh->nexthdr == srhinfo->next_hdr))) + return false; + + /* Header Extension Length matching */ + if (srhinfo->mt_flags & IP6T_SRH_LEN_EQ) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_EQ, + !(srh->hdrlen == srhinfo->hdr_len))) + return false; + if (srhinfo->mt_flags & IP6T_SRH_LEN_GT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_GT, + !(srh->hdrlen > srhinfo->hdr_len))) + return false; + if (srhinfo->mt_flags & IP6T_SRH_LEN_LT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_LT, + !(srh->hdrlen < srhinfo->hdr_len))) + return false; + + /* Segments Left matching */ + if (srhinfo->mt_flags & IP6T_SRH_SEGS_EQ) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_EQ, + !(srh->segments_left == srhinfo->segs_left))) + return false; + if (srhinfo->mt_flags & IP6T_SRH_SEGS_GT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_GT, + !(srh->segments_left > srhinfo->segs_left))) + return false; + if (srhinfo->mt_flags & IP6T_SRH_SEGS_LT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_LT, + !(srh->segments_left < srhinfo->segs_left))) + return false; + + /** + * Last Entry matching + * Last_Entry field was introduced in revision 6 of the SRH draft. + * It was called First_Segment in the previous revision + */ + if (srhinfo->mt_flags & IP6T_SRH_LAST_EQ) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_EQ, + !(srh->first_segment == srhinfo->last_entry))) + return false; + if (srhinfo->mt_flags & IP6T_SRH_LAST_GT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_GT, + !(srh->first_segment > srhinfo->last_entry))) + return false; + if (srhinfo->mt_flags & IP6T_SRH_LAST_LT) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_LT, + !(srh->first_segment < srhinfo->last_entry))) + return false; + + /** + * Tag matchig + * Tag field was introduced in revision 6 of the SRH draft + */ + if (srhinfo->mt_flags & IP6T_SRH_TAG) + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_TAG, + !(srh->tag == srhinfo->tag))) + return false; + + /* Previous SID matching */ + if (srhinfo->mt_flags & IP6T_SRH_PSID) { + if (srh->segments_left == srh->first_segment) + return false; + psidoff = srhoff + sizeof(struct ipv6_sr_hdr) + + ((srh->segments_left + 1) * sizeof(struct in6_addr)); + psid = skb_header_pointer(skb, psidoff, sizeof(_psid), &_psid); + if (!psid) + return false; + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_PSID, + ipv6_masked_addr_cmp(psid, &srhinfo->psid_msk, + &srhinfo->psid_addr))) + return false; + } + + /* Next SID matching */ + if (srhinfo->mt_flags & IP6T_SRH_NSID) { + if (srh->segments_left == 0) + return false; + nsidoff = srhoff + sizeof(struct ipv6_sr_hdr) + + ((srh->segments_left - 1) * sizeof(struct in6_addr)); + nsid = skb_header_pointer(skb, nsidoff, sizeof(_nsid), &_nsid); + if (!nsid) + return false; + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_NSID, + ipv6_masked_addr_cmp(nsid, &srhinfo->nsid_msk, + &srhinfo->nsid_addr))) + return false; + } + + /* Last SID matching */ + if (srhinfo->mt_flags & IP6T_SRH_LSID) { + lsidoff = srhoff + sizeof(struct ipv6_sr_hdr); + lsid = skb_header_pointer(skb, lsidoff, sizeof(_lsid), &_lsid); + if (!lsid) + return false; + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LSID, + ipv6_masked_addr_cmp(lsid, &srhinfo->lsid_msk, + &srhinfo->lsid_addr))) + return false; + } + return true; +} + +static int srh_mt6_check(const struct xt_mtchk_param *par) +{ + const struct ip6t_srh *srhinfo = par->matchinfo; + + if (srhinfo->mt_flags & ~IP6T_SRH_MASK) { + pr_info_ratelimited("unknown srh match flags %X\n", + srhinfo->mt_flags); + return -EINVAL; + } + + if (srhinfo->mt_invflags & ~IP6T_SRH_INV_MASK) { + pr_info_ratelimited("unknown srh invflags %X\n", + srhinfo->mt_invflags); + return -EINVAL; + } + + return 0; +} + +static int srh1_mt6_check(const struct xt_mtchk_param *par) +{ + const struct ip6t_srh1 *srhinfo = par->matchinfo; + + if (srhinfo->mt_flags & ~IP6T_SRH_MASK) { + pr_info_ratelimited("unknown srh match flags %X\n", + srhinfo->mt_flags); + return -EINVAL; + } + + if (srhinfo->mt_invflags & ~IP6T_SRH_INV_MASK) { + pr_info_ratelimited("unknown srh invflags %X\n", + srhinfo->mt_invflags); + return -EINVAL; + } + + return 0; +} + +static struct xt_match srh_mt6_reg[] __read_mostly = { + { + .name = "srh", + .revision = 0, + .family = NFPROTO_IPV6, + .match = srh_mt6, + .matchsize = sizeof(struct ip6t_srh), + .checkentry = srh_mt6_check, + .me = THIS_MODULE, + }, + { + .name = "srh", + .revision = 1, + .family = NFPROTO_IPV6, + .match = srh1_mt6, + .matchsize = sizeof(struct ip6t_srh1), + .checkentry = srh1_mt6_check, + .me = THIS_MODULE, + } +}; + +static int __init srh_mt6_init(void) +{ + return xt_register_matches(srh_mt6_reg, ARRAY_SIZE(srh_mt6_reg)); +} + +static void __exit srh_mt6_exit(void) +{ + xt_unregister_matches(srh_mt6_reg, ARRAY_SIZE(srh_mt6_reg)); +} + +module_init(srh_mt6_init); +module_exit(srh_mt6_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Xtables: IPv6 Segment Routing Header match"); +MODULE_AUTHOR("Ahmed Abdelsalam <amsalam20@gmail.com>"); |