diff options
Diffstat (limited to 'net/netfilter/xt_ecn.c')
| -rw-r--r-- | net/netfilter/xt_ecn.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/net/netfilter/xt_ecn.c b/net/netfilter/xt_ecn.c new file mode 100644 index 000000000..b96e8203a --- /dev/null +++ b/net/netfilter/xt_ecn.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Xtables module for matching the value of the IPv4/IPv6 and TCP ECN bits + * + * (C) 2002 by Harald Welte <laforge@gnumonks.org> + * (C) 2011 Patrick McHardy <kaber@trash.net> + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/in.h> +#include <linux/ip.h> +#include <net/ip.h> +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/tcp.h> + +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter/xt_ecn.h> +#include <linux/netfilter_ipv4/ip_tables.h> +#include <linux/netfilter_ipv6/ip6_tables.h> + +MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); +MODULE_DESCRIPTION("Xtables: Explicit Congestion Notification (ECN) flag match"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("ipt_ecn"); +MODULE_ALIAS("ip6t_ecn"); + +static bool match_tcp(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct xt_ecn_info *einfo = par->matchinfo; + struct tcphdr _tcph; + const struct tcphdr *th; + + /* In practice, TCP match does this, so can't fail. But let's + * be good citizens. + */ + th = skb_header_pointer(skb, par->thoff, sizeof(_tcph), &_tcph); + if (th == NULL) + return false; + + if (einfo->operation & XT_ECN_OP_MATCH_ECE) { + if (einfo->invert & XT_ECN_OP_MATCH_ECE) { + if (th->ece == 1) + return false; + } else { + if (th->ece == 0) + return false; + } + } + + if (einfo->operation & XT_ECN_OP_MATCH_CWR) { + if (einfo->invert & XT_ECN_OP_MATCH_CWR) { + if (th->cwr == 1) + return false; + } else { + if (th->cwr == 0) + return false; + } + } + + return true; +} + +static inline bool match_ip(const struct sk_buff *skb, + const struct xt_ecn_info *einfo) +{ + return ((ip_hdr(skb)->tos & XT_ECN_IP_MASK) == einfo->ip_ect) ^ + !!(einfo->invert & XT_ECN_OP_MATCH_IP); +} + +static bool ecn_mt4(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct xt_ecn_info *info = par->matchinfo; + + if (info->operation & XT_ECN_OP_MATCH_IP && !match_ip(skb, info)) + return false; + + if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) && + !match_tcp(skb, par)) + return false; + + return true; +} + +static int ecn_mt_check4(const struct xt_mtchk_param *par) +{ + const struct xt_ecn_info *info = par->matchinfo; + const struct ipt_ip *ip = par->entryinfo; + + if (info->operation & XT_ECN_OP_MATCH_MASK) + return -EINVAL; + + if (info->invert & XT_ECN_OP_MATCH_MASK) + return -EINVAL; + + if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) && + (ip->proto != IPPROTO_TCP || ip->invflags & IPT_INV_PROTO)) { + pr_info_ratelimited("cannot match TCP bits for non-tcp packets\n"); + return -EINVAL; + } + + return 0; +} + +static inline bool match_ipv6(const struct sk_buff *skb, + const struct xt_ecn_info *einfo) +{ + return (((ipv6_hdr(skb)->flow_lbl[0] >> 4) & XT_ECN_IP_MASK) == + einfo->ip_ect) ^ + !!(einfo->invert & XT_ECN_OP_MATCH_IP); +} + +static bool ecn_mt6(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct xt_ecn_info *info = par->matchinfo; + + if (info->operation & XT_ECN_OP_MATCH_IP && !match_ipv6(skb, info)) + return false; + + if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) && + !match_tcp(skb, par)) + return false; + + return true; +} + +static int ecn_mt_check6(const struct xt_mtchk_param *par) +{ + const struct xt_ecn_info *info = par->matchinfo; + const struct ip6t_ip6 *ip = par->entryinfo; + + if (info->operation & XT_ECN_OP_MATCH_MASK) + return -EINVAL; + + if (info->invert & XT_ECN_OP_MATCH_MASK) + return -EINVAL; + + if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) && + (ip->proto != IPPROTO_TCP || ip->invflags & IP6T_INV_PROTO)) { + pr_info_ratelimited("cannot match TCP bits for non-tcp packets\n"); + return -EINVAL; + } + + return 0; +} + +static struct xt_match ecn_mt_reg[] __read_mostly = { + { + .name = "ecn", + .family = NFPROTO_IPV4, + .match = ecn_mt4, + .matchsize = sizeof(struct xt_ecn_info), + .checkentry = ecn_mt_check4, + .me = THIS_MODULE, + }, + { + .name = "ecn", + .family = NFPROTO_IPV6, + .match = ecn_mt6, + .matchsize = sizeof(struct xt_ecn_info), + .checkentry = ecn_mt_check6, + .me = THIS_MODULE, + }, +}; + +static int __init ecn_mt_init(void) +{ + return xt_register_matches(ecn_mt_reg, ARRAY_SIZE(ecn_mt_reg)); +} + +static void __exit ecn_mt_exit(void) +{ + xt_unregister_matches(ecn_mt_reg, ARRAY_SIZE(ecn_mt_reg)); +} + +module_init(ecn_mt_init); +module_exit(ecn_mt_exit); |