diff options
Diffstat (limited to 'net/ipv4/netfilter/ipt_ah.c')
-rw-r--r-- | net/ipv4/netfilter/ipt_ah.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ipt_ah.c b/net/ipv4/netfilter/ipt_ah.c new file mode 100644 index 000000000..161ba412c --- /dev/null +++ b/net/ipv4/netfilter/ipt_ah.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Kernel module to match AH parameters. */ +/* (C) 1999-2000 Yon Uriarte <yon@astaro.de> + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/in.h> +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/ip.h> + +#include <linux/netfilter_ipv4/ipt_ah.h> +#include <linux/netfilter/x_tables.h> + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>"); +MODULE_DESCRIPTION("Xtables: IPv4 IPsec-AH SPI match"); + +/* Returns 1 if the spi is matched by the range, 0 otherwise */ +static inline bool +spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert) +{ + bool r; + pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n", + invert ? '!' : ' ', min, spi, max); + r = (spi >= min && spi <= max) ^ invert; + pr_debug(" result %s\n", r ? "PASS" : "FAILED"); + return r; +} + +static bool ah_mt(const struct sk_buff *skb, struct xt_action_param *par) +{ + struct ip_auth_hdr _ahdr; + const struct ip_auth_hdr *ah; + const struct ipt_ah *ahinfo = par->matchinfo; + + /* Must not be a fragment. */ + if (par->fragoff != 0) + return false; + + ah = skb_header_pointer(skb, par->thoff, sizeof(_ahdr), &_ahdr); + if (ah == NULL) { + /* We've been asked to examine this packet, and we + * can't. Hence, no choice but to drop. + */ + pr_debug("Dropping evil AH tinygram.\n"); + par->hotdrop = true; + return false; + } + + return spi_match(ahinfo->spis[0], ahinfo->spis[1], + ntohl(ah->spi), + !!(ahinfo->invflags & IPT_AH_INV_SPI)); +} + +static int ah_mt_check(const struct xt_mtchk_param *par) +{ + const struct ipt_ah *ahinfo = par->matchinfo; + + /* Must specify no unknown invflags */ + if (ahinfo->invflags & ~IPT_AH_INV_MASK) { + pr_debug("unknown flags %X\n", ahinfo->invflags); + return -EINVAL; + } + return 0; +} + +static struct xt_match ah_mt_reg __read_mostly = { + .name = "ah", + .family = NFPROTO_IPV4, + .match = ah_mt, + .matchsize = sizeof(struct ipt_ah), + .proto = IPPROTO_AH, + .checkentry = ah_mt_check, + .me = THIS_MODULE, +}; + +static int __init ah_mt_init(void) +{ + return xt_register_match(&ah_mt_reg); +} + +static void __exit ah_mt_exit(void) +{ + xt_unregister_match(&ah_mt_reg); +} + +module_init(ah_mt_init); +module_exit(ah_mt_exit); |