// SPDX-License-Identifier: GPL-2.0-only
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/* x_tables module for setting the IPv4/IPv6 DSCP field, Version 1.8
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*
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* (C) 2002 by Harald Welte <laforge@netfilter.org>
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* based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
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*
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* See RFC2474 for a description of the DSCP field within the IP Header.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <net/dsfield.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter/xt_DSCP.h>
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MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
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MODULE_DESCRIPTION("Xtables: DSCP/TOS field modification");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("ipt_DSCP");
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MODULE_ALIAS("ip6t_DSCP");
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MODULE_ALIAS("ipt_TOS");
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MODULE_ALIAS("ip6t_TOS");
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static unsigned int
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dscp_tg(struct sk_buff *skb, const struct xt_action_param *par)
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{
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const struct xt_DSCP_info *dinfo = par->targinfo;
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u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
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if (dscp != dinfo->dscp) {
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if (skb_ensure_writable(skb, sizeof(struct iphdr)))
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return NF_DROP;
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ipv4_change_dsfield(ip_hdr(skb),
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(__force __u8)(~XT_DSCP_MASK),
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dinfo->dscp << XT_DSCP_SHIFT);
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}
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return XT_CONTINUE;
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}
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static unsigned int
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dscp_tg6(struct sk_buff *skb, const struct xt_action_param *par)
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{
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const struct xt_DSCP_info *dinfo = par->targinfo;
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u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
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if (dscp != dinfo->dscp) {
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if (skb_ensure_writable(skb, sizeof(struct ipv6hdr)))
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return NF_DROP;
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ipv6_change_dsfield(ipv6_hdr(skb),
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(__force __u8)(~XT_DSCP_MASK),
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dinfo->dscp << XT_DSCP_SHIFT);
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}
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return XT_CONTINUE;
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}
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static int dscp_tg_check(const struct xt_tgchk_param *par)
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{
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const struct xt_DSCP_info *info = par->targinfo;
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if (info->dscp > XT_DSCP_MAX)
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return -EDOM;
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return 0;
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}
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static unsigned int
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tos_tg(struct sk_buff *skb, const struct xt_action_param *par)
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{
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const struct xt_tos_target_info *info = par->targinfo;
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struct iphdr *iph = ip_hdr(skb);
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u_int8_t orig, nv;
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orig = ipv4_get_dsfield(iph);
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nv = (orig & ~info->tos_mask) ^ info->tos_value;
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if (orig != nv) {
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if (skb_ensure_writable(skb, sizeof(struct iphdr)))
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return NF_DROP;
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iph = ip_hdr(skb);
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ipv4_change_dsfield(iph, 0, nv);
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}
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return XT_CONTINUE;
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}
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static unsigned int
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tos_tg6(struct sk_buff *skb, const struct xt_action_param *par)
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{
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const struct xt_tos_target_info *info = par->targinfo;
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struct ipv6hdr *iph = ipv6_hdr(skb);
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u_int8_t orig, nv;
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orig = ipv6_get_dsfield(iph);
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nv = (orig & ~info->tos_mask) ^ info->tos_value;
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if (orig != nv) {
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if (skb_ensure_writable(skb, sizeof(struct iphdr)))
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return NF_DROP;
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iph = ipv6_hdr(skb);
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ipv6_change_dsfield(iph, 0, nv);
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}
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return XT_CONTINUE;
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}
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static struct xt_target dscp_tg_reg[] __read_mostly = {
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{
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.name = "DSCP",
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.family = NFPROTO_IPV4,
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.checkentry = dscp_tg_check,
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.target = dscp_tg,
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.targetsize = sizeof(struct xt_DSCP_info),
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.table = "mangle",
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.me = THIS_MODULE,
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},
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{
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.name = "DSCP",
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.family = NFPROTO_IPV6,
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.checkentry = dscp_tg_check,
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.target = dscp_tg6,
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.targetsize = sizeof(struct xt_DSCP_info),
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.table = "mangle",
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.me = THIS_MODULE,
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},
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{
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.name = "TOS",
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.revision = 1,
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.family = NFPROTO_IPV4,
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.table = "mangle",
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.target = tos_tg,
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.targetsize = sizeof(struct xt_tos_target_info),
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.me = THIS_MODULE,
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},
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{
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.name = "TOS",
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.revision = 1,
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.family = NFPROTO_IPV6,
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.table = "mangle",
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.target = tos_tg6,
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.targetsize = sizeof(struct xt_tos_target_info),
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.me = THIS_MODULE,
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},
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};
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static int __init dscp_tg_init(void)
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{
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return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
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}
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static void __exit dscp_tg_exit(void)
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{
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xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
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}
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module_init(dscp_tg_init);
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module_exit(dscp_tg_exit);
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