From e6f30c731718db45cec380964dfee210307cfc4a Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Fri, 18 Jan 2013 07:17:30 +0000 Subject: [PATCH] netfilter: x_tables: add xt_bpf match Support arbitrary linux socket filter (BPF) programs as x_tables match rules. This allows for very expressive filters, and on platforms with BPF JIT appears competitive with traditional hardcoded iptables rules using the u32 match. The size of the filter has been artificially limited to 64 instructions maximum to avoid bloating the size of each rule using this new match. Signed-off-by: Willem de Bruijn Signed-off-by: Pablo Neira Ayuso --- include/uapi/linux/netfilter/xt_bpf.h | 17 +++++++ net/netfilter/Kconfig | 9 ++++ net/netfilter/Makefile | 1 + net/netfilter/xt_bpf.c | 73 +++++++++++++++++++++++++++ 4 files changed, 100 insertions(+) create mode 100644 include/uapi/linux/netfilter/xt_bpf.h create mode 100644 net/netfilter/xt_bpf.c diff --git a/include/uapi/linux/netfilter/xt_bpf.h b/include/uapi/linux/netfilter/xt_bpf.h new file mode 100644 index 000000000000..5dda450eb55b --- /dev/null +++ b/include/uapi/linux/netfilter/xt_bpf.h @@ -0,0 +1,17 @@ +#ifndef _XT_BPF_H +#define _XT_BPF_H + +#include +#include + +#define XT_BPF_MAX_NUM_INSTR 64 + +struct xt_bpf_info { + __u16 bpf_program_num_elem; + struct sock_filter bpf_program[XT_BPF_MAX_NUM_INSTR]; + + /* only used in the kernel */ + struct sk_filter *filter __attribute__((aligned(8))); +}; + +#endif /*_XT_BPF_H */ diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index bb48607d4ee4..eb2c8ebf6d99 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -811,6 +811,15 @@ config NETFILTER_XT_MATCH_ADDRTYPE If you want to compile it as a module, say M here and read . If unsure, say `N'. +config NETFILTER_XT_MATCH_BPF + tristate '"bpf" match support' + depends on NETFILTER_ADVANCED + help + BPF matching applies a linux socket filter to each packet and + accepts those for which the filter returns non-zero. + + To compile it as a module, choose M here. If unsure, say N. + config NETFILTER_XT_MATCH_CLUSTER tristate '"cluster" match support' depends on NF_CONNTRACK diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index b3bbda60945e..a1abf87d43bf 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -99,6 +99,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_IDLETIMER) += xt_IDLETIMER.o # matches obj-$(CONFIG_NETFILTER_XT_MATCH_ADDRTYPE) += xt_addrtype.o +obj-$(CONFIG_NETFILTER_XT_MATCH_BPF) += xt_bpf.o obj-$(CONFIG_NETFILTER_XT_MATCH_CLUSTER) += xt_cluster.o obj-$(CONFIG_NETFILTER_XT_MATCH_COMMENT) += xt_comment.o obj-$(CONFIG_NETFILTER_XT_MATCH_CONNBYTES) += xt_connbytes.o diff --git a/net/netfilter/xt_bpf.c b/net/netfilter/xt_bpf.c new file mode 100644 index 000000000000..12d4da8e6c77 --- /dev/null +++ b/net/netfilter/xt_bpf.c @@ -0,0 +1,73 @@ +/* Xtables module to match packets using a BPF filter. + * Copyright 2013 Google Inc. + * Written by Willem de Bruijn + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include + +#include +#include + +MODULE_AUTHOR("Willem de Bruijn "); +MODULE_DESCRIPTION("Xtables: BPF filter match"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("ipt_bpf"); +MODULE_ALIAS("ip6t_bpf"); + +static int bpf_mt_check(const struct xt_mtchk_param *par) +{ + struct xt_bpf_info *info = par->matchinfo; + struct sock_fprog program; + + program.len = info->bpf_program_num_elem; + program.filter = (struct sock_filter __user *) info->bpf_program; + if (sk_unattached_filter_create(&info->filter, &program)) { + pr_info("bpf: check failed: parse error\n"); + return -EINVAL; + } + + return 0; +} + +static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct xt_bpf_info *info = par->matchinfo; + + return SK_RUN_FILTER(info->filter, skb); +} + +static void bpf_mt_destroy(const struct xt_mtdtor_param *par) +{ + const struct xt_bpf_info *info = par->matchinfo; + sk_unattached_filter_destroy(info->filter); +} + +static struct xt_match bpf_mt_reg __read_mostly = { + .name = "bpf", + .revision = 0, + .family = NFPROTO_UNSPEC, + .checkentry = bpf_mt_check, + .match = bpf_mt, + .destroy = bpf_mt_destroy, + .matchsize = sizeof(struct xt_bpf_info), + .me = THIS_MODULE, +}; + +static int __init bpf_mt_init(void) +{ + return xt_register_match(&bpf_mt_reg); +} + +static void __exit bpf_mt_exit(void) +{ + xt_unregister_match(&bpf_mt_reg); +} + +module_init(bpf_mt_init); +module_exit(bpf_mt_exit); -- 2.30.2