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// SPDX-License-Identifier: GPL-2.0-only
/* x_tables module for setting the IPv4/IPv6 DSCP field, Version 1.8
*
* (C) 2002 by Harald Welte <laforge@netfilter.org>
* based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
*
* See RFC2474 for a description of the DSCP field within the IP Header.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <net/dsfield.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_DSCP.h>
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_DESCRIPTION("Xtables: DSCP/TOS field modification");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_DSCP");
MODULE_ALIAS("ip6t_DSCP");
MODULE_ALIAS("ipt_TOS");
MODULE_ALIAS("ip6t_TOS");
#define XT_DSCP_ECN_MASK 3u
static unsigned int
dscp_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct xt_DSCP_info *dinfo = par->targinfo;
u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
if (dscp != dinfo->dscp) {
if (skb_ensure_writable(skb, sizeof(struct iphdr)))
return NF_DROP;
ipv4_change_dsfield(ip_hdr(skb), XT_DSCP_ECN_MASK,
dinfo->dscp << XT_DSCP_SHIFT);
}
return XT_CONTINUE;
}
static unsigned int
dscp_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct xt_DSCP_info *dinfo = par->targinfo;
u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
if (dscp != dinfo->dscp) {
if (skb_ensure_writable(skb, sizeof(struct ipv6hdr)))
return NF_DROP;
ipv6_change_dsfield(ipv6_hdr(skb), XT_DSCP_ECN_MASK,
dinfo->dscp << XT_DSCP_SHIFT);
}
return XT_CONTINUE;
}
static int dscp_tg_check(const struct xt_tgchk_param *par)
{
const struct xt_DSCP_info *info = par->targinfo;
if (info->dscp > XT_DSCP_MAX)
return -EDOM;
return 0;
}
static unsigned int
tos_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct xt_tos_target_info *info = par->targinfo;
struct iphdr *iph = ip_hdr(skb);
u_int8_t orig, nv;
orig = ipv4_get_dsfield(iph);
nv = (orig & ~info->tos_mask) ^ info->tos_value;
if (orig != nv) {
if (skb_ensure_writable(skb, sizeof(struct iphdr)))
return NF_DROP;
iph = ip_hdr(skb);
ipv4_change_dsfield(iph, 0, nv);
}
return XT_CONTINUE;
}
static unsigned int
tos_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct xt_tos_target_info *info = par->targinfo;
struct ipv6hdr *iph = ipv6_hdr(skb);
u_int8_t orig, nv;
orig = ipv6_get_dsfield(iph);
nv = (orig & ~info->tos_mask) ^ info->tos_value;
if (orig != nv) {
if (skb_ensure_writable(skb, sizeof(struct iphdr)))
return NF_DROP;
iph = ipv6_hdr(skb);
ipv6_change_dsfield(iph, 0, nv);
}
return XT_CONTINUE;
}
static struct xt_target dscp_tg_reg[] __read_mostly = {
{
.name = "DSCP",
.family = NFPROTO_IPV4,
.checkentry = dscp_tg_check,
.target = dscp_tg,
.targetsize = sizeof(struct xt_DSCP_info),
.table = "mangle",
.me = THIS_MODULE,
},
{
.name = "DSCP",
.family = NFPROTO_IPV6,
.checkentry = dscp_tg_check,
.target = dscp_tg6,
.targetsize = sizeof(struct xt_DSCP_info),
.table = "mangle",
.me = THIS_MODULE,
},
{
.name = "TOS",
.revision = 1,
.family = NFPROTO_IPV4,
.table = "mangle",
.target = tos_tg,
.targetsize = sizeof(struct xt_tos_target_info),
.me = THIS_MODULE,
},
{
.name = "TOS",
.revision = 1,
.family = NFPROTO_IPV6,
.table = "mangle",
.target = tos_tg6,
.targetsize = sizeof(struct xt_tos_target_info),
.me = THIS_MODULE,
},
};
static int __init dscp_tg_init(void)
{
return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
}
static void __exit dscp_tg_exit(void)
{
xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
}
module_init(dscp_tg_init);
module_exit(dscp_tg_exit);
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