diff options
Diffstat (limited to 'net/ipv6/netfilter/ip6t_frag.c')
| -rw-r--r-- | net/ipv6/netfilter/ip6t_frag.c | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/net/ipv6/netfilter/ip6t_frag.c b/net/ipv6/netfilter/ip6t_frag.c new file mode 100644 index 000000000..3aad64393 --- /dev/null +++ b/net/ipv6/netfilter/ip6t_frag.c @@ -0,0 +1,132 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Kernel module to match FRAG parameters. */ + +/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> + */ +#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/checksum.h> +#include <net/ipv6.h> + +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter_ipv6/ip6_tables.h> +#include <linux/netfilter_ipv6/ip6t_frag.h> + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Xtables: IPv6 fragment match"); +MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); + +/* Returns 1 if the id is matched by the range, 0 otherwise */ +static inline bool +id_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert) +{ + bool r; + pr_debug("id_match:%c 0x%x <= 0x%x <= 0x%x\n", invert ? '!' : ' ', + min, id, max); + r = (id >= min && id <= max) ^ invert; + pr_debug(" result %s\n", r ? "PASS" : "FAILED"); + return r; +} + +static bool +frag_mt6(const struct sk_buff *skb, struct xt_action_param *par) +{ + struct frag_hdr _frag; + const struct frag_hdr *fh; + const struct ip6t_frag *fraginfo = par->matchinfo; + unsigned int ptr = 0; + int err; + + err = ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL, NULL); + if (err < 0) { + if (err != -ENOENT) + par->hotdrop = true; + return false; + } + + fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag); + if (fh == NULL) { + par->hotdrop = true; + return false; + } + + pr_debug("INFO %04X ", fh->frag_off); + pr_debug("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7); + pr_debug("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6); + pr_debug("MF %04X ", fh->frag_off & htons(IP6_MF)); + pr_debug("ID %u %08X\n", ntohl(fh->identification), + ntohl(fh->identification)); + + pr_debug("IPv6 FRAG id %02X ", + id_match(fraginfo->ids[0], fraginfo->ids[1], + ntohl(fh->identification), + !!(fraginfo->invflags & IP6T_FRAG_INV_IDS))); + pr_debug("res %02X %02X%04X %02X ", + fraginfo->flags & IP6T_FRAG_RES, fh->reserved, + ntohs(fh->frag_off) & 0x6, + !((fraginfo->flags & IP6T_FRAG_RES) && + (fh->reserved || (ntohs(fh->frag_off) & 0x06)))); + pr_debug("first %02X %02X %02X ", + fraginfo->flags & IP6T_FRAG_FST, + ntohs(fh->frag_off) & ~0x7, + !((fraginfo->flags & IP6T_FRAG_FST) && + (ntohs(fh->frag_off) & ~0x7))); + pr_debug("mf %02X %02X %02X ", + fraginfo->flags & IP6T_FRAG_MF, + ntohs(fh->frag_off) & IP6_MF, + !((fraginfo->flags & IP6T_FRAG_MF) && + !((ntohs(fh->frag_off) & IP6_MF)))); + pr_debug("last %02X %02X %02X\n", + fraginfo->flags & IP6T_FRAG_NMF, + ntohs(fh->frag_off) & IP6_MF, + !((fraginfo->flags & IP6T_FRAG_NMF) && + (ntohs(fh->frag_off) & IP6_MF))); + + return id_match(fraginfo->ids[0], fraginfo->ids[1], + ntohl(fh->identification), + !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)) && + !((fraginfo->flags & IP6T_FRAG_RES) && + (fh->reserved || (ntohs(fh->frag_off) & 0x6))) && + !((fraginfo->flags & IP6T_FRAG_FST) && + (ntohs(fh->frag_off) & ~0x7)) && + !((fraginfo->flags & IP6T_FRAG_MF) && + !(ntohs(fh->frag_off) & IP6_MF)) && + !((fraginfo->flags & IP6T_FRAG_NMF) && + (ntohs(fh->frag_off) & IP6_MF)); +} + +static int frag_mt6_check(const struct xt_mtchk_param *par) +{ + const struct ip6t_frag *fraginfo = par->matchinfo; + + if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) { + pr_debug("unknown flags %X\n", fraginfo->invflags); + return -EINVAL; + } + return 0; +} + +static struct xt_match frag_mt6_reg __read_mostly = { + .name = "frag", + .family = NFPROTO_IPV6, + .match = frag_mt6, + .matchsize = sizeof(struct ip6t_frag), + .checkentry = frag_mt6_check, + .me = THIS_MODULE, +}; + +static int __init frag_mt6_init(void) +{ + return xt_register_match(&frag_mt6_reg); +} + +static void __exit frag_mt6_exit(void) +{ + xt_unregister_match(&frag_mt6_reg); +} + +module_init(frag_mt6_init); +module_exit(frag_mt6_exit); |