diff options
Diffstat (limited to 'net')
| -rw-r--r-- | net/netfilter/Kconfig | 16 | ||||
| -rw-r--r-- | net/netfilter/Makefile | 1 | ||||
| -rw-r--r-- | net/netfilter/xt_CHECKSUM.c | 70 |
3 files changed, 87 insertions, 0 deletions
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index aa2f106..5fb8efa 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -326,6 +326,22 @@ config NETFILTER_XT_CONNMARK comment "Xtables targets" +config NETFILTER_XT_TARGET_CHECKSUM + tristate "CHECKSUM target support" + depends on IP_NF_MANGLE || IP6_NF_MANGLE + depends on NETFILTER_ADVANCED + ---help--- + This option adds a `CHECKSUM' target, which can be used in the iptables mangle + table. + + You can use this target to compute and fill in the checksum in + a packet that lacks a checksum. This is particularly useful, + if you need to work around old applications such as dhcp clients, + that do not work well with checksum offloads, but don't want to disable + checksum offload in your device. + + To compile it as a module, choose M here. If unsure, say N. + config NETFILTER_XT_TARGET_CLASSIFY tristate '"CLASSIFY" target support' depends on NETFILTER_ADVANCED diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index e28420a..36ef8e6 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -45,6 +45,7 @@ obj-$(CONFIG_NETFILTER_XT_MARK) += xt_mark.o obj-$(CONFIG_NETFILTER_XT_CONNMARK) += xt_connmark.o # targets +obj-$(CONFIG_NETFILTER_XT_TARGET_CHECKSUM) += xt_CHECKSUM.o obj-$(CONFIG_NETFILTER_XT_TARGET_CLASSIFY) += xt_CLASSIFY.o obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o obj-$(CONFIG_NETFILTER_XT_TARGET_CT) += xt_CT.o diff --git a/net/netfilter/xt_CHECKSUM.c b/net/netfilter/xt_CHECKSUM.c new file mode 100644 index 0000000..0f642ef --- /dev/null +++ b/net/netfilter/xt_CHECKSUM.c @@ -0,0 +1,70 @@ +/* iptables module for the packet checksum mangling + * + * (C) 2002 by Harald Welte <laforge@netfilter.org> + * (C) 2010 Red Hat, Inc. + * + * Author: Michael S. Tsirkin <mst@redhat.com> + * + * 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. +*/ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/module.h> +#include <linux/skbuff.h> + +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter/xt_CHECKSUM.h> + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Michael S. Tsirkin <mst@redhat.com>"); +MODULE_DESCRIPTION("Xtables: checksum modification"); +MODULE_ALIAS("ipt_CHECKSUM"); +MODULE_ALIAS("ip6t_CHECKSUM"); + +static unsigned int +checksum_tg(struct sk_buff *skb, const struct xt_action_param *par) +{ + if (skb->ip_summed == CHECKSUM_PARTIAL) + skb_checksum_help(skb); + + return XT_CONTINUE; +} + +static int checksum_tg_check(const struct xt_tgchk_param *par) +{ + const struct xt_CHECKSUM_info *einfo = par->targinfo; + + if (einfo->operation & ~XT_CHECKSUM_OP_FILL) { + pr_info("unsupported CHECKSUM operation %x\n", einfo->operation); + return -EINVAL; + } + if (!einfo->operation) { + pr_info("no CHECKSUM operation enabled\n"); + return -EINVAL; + } + return 0; +} + +static struct xt_target checksum_tg_reg __read_mostly = { + .name = "CHECKSUM", + .family = NFPROTO_UNSPEC, + .target = checksum_tg, + .targetsize = sizeof(struct xt_CHECKSUM_info), + .table = "mangle", + .checkentry = checksum_tg_check, + .me = THIS_MODULE, +}; + +static int __init checksum_tg_init(void) +{ + return xt_register_target(&checksum_tg_reg); +} + +static void __exit checksum_tg_exit(void) +{ + xt_unregister_target(&checksum_tg_reg); +} + +module_init(checksum_tg_init); +module_exit(checksum_tg_exit); |