1/* x_tables module for setting the IPv4/IPv6 DSCP field, Version 1.8 2 * 3 * (C) 2002 by Harald Welte <laforge@netfilter.org> 4 * based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * See RFC2474 for a description of the DSCP field within the IP Header. 11*/ 12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 13#include <linux/module.h> 14#include <linux/skbuff.h> 15#include <linux/ip.h> 16#include <linux/ipv6.h> 17#include <net/dsfield.h> 18 19#include <linux/netfilter/x_tables.h> 20#include <linux/netfilter/xt_DSCP.h> 21 22MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); 23MODULE_DESCRIPTION("Xtables: DSCP/TOS field modification"); 24MODULE_LICENSE("GPL"); 25MODULE_ALIAS("ipt_DSCP"); 26MODULE_ALIAS("ip6t_DSCP"); 27MODULE_ALIAS("ipt_TOS"); 28MODULE_ALIAS("ip6t_TOS"); 29 30static unsigned int 31dscp_tg(struct sk_buff *skb, const struct xt_action_param *par) 32{ 33 const struct xt_DSCP_info *dinfo = par->targinfo; 34 u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT; 35 36 if (dscp != dinfo->dscp) { 37 if (!skb_make_writable(skb, sizeof(struct iphdr))) 38 return NF_DROP; 39 40 ipv4_change_dsfield(ip_hdr(skb), (__u8)(~XT_DSCP_MASK), 41 dinfo->dscp << XT_DSCP_SHIFT); 42 43 } 44 return XT_CONTINUE; 45} 46 47static unsigned int 48dscp_tg6(struct sk_buff *skb, const struct xt_action_param *par) 49{ 50 const struct xt_DSCP_info *dinfo = par->targinfo; 51 u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT; 52 53 if (dscp != dinfo->dscp) { 54 if (!skb_make_writable(skb, sizeof(struct ipv6hdr))) 55 return NF_DROP; 56 57 ipv6_change_dsfield(ipv6_hdr(skb), (__u8)(~XT_DSCP_MASK), 58 dinfo->dscp << XT_DSCP_SHIFT); 59 } 60 return XT_CONTINUE; 61} 62 63static int dscp_tg_check(const struct xt_tgchk_param *par) 64{ 65 const struct xt_DSCP_info *info = par->targinfo; 66 67 if (info->dscp > XT_DSCP_MAX) { 68 pr_info("dscp %x out of range\n", info->dscp); 69 return -EDOM; 70 } 71 return 0; 72} 73 74static unsigned int 75tos_tg(struct sk_buff *skb, const struct xt_action_param *par) 76{ 77 const struct xt_tos_target_info *info = par->targinfo; 78 struct iphdr *iph = ip_hdr(skb); 79 u_int8_t orig, nv; 80 81 orig = ipv4_get_dsfield(iph); 82 nv = (orig & ~info->tos_mask) ^ info->tos_value; 83 84 if (orig != nv) { 85 if (!skb_make_writable(skb, sizeof(struct iphdr))) 86 return NF_DROP; 87 iph = ip_hdr(skb); 88 ipv4_change_dsfield(iph, 0, nv); 89 } 90 91 return XT_CONTINUE; 92} 93 94static unsigned int 95tos_tg6(struct sk_buff *skb, const struct xt_action_param *par) 96{ 97 const struct xt_tos_target_info *info = par->targinfo; 98 struct ipv6hdr *iph = ipv6_hdr(skb); 99 u_int8_t orig, nv; 100 101 orig = ipv6_get_dsfield(iph); 102 nv = (orig & info->tos_mask) ^ info->tos_value; 103 104 if (orig != nv) { 105 if (!skb_make_writable(skb, sizeof(struct iphdr))) 106 return NF_DROP; 107 iph = ipv6_hdr(skb); 108 ipv6_change_dsfield(iph, 0, nv); 109 } 110 111 return XT_CONTINUE; 112} 113 114static struct xt_target dscp_tg_reg[] __read_mostly = { 115 { 116 .name = "DSCP", 117 .family = NFPROTO_IPV4, 118 .checkentry = dscp_tg_check, 119 .target = dscp_tg, 120 .targetsize = sizeof(struct xt_DSCP_info), 121 .table = "mangle", 122 .me = THIS_MODULE, 123 }, 124 { 125 .name = "DSCP", 126 .family = NFPROTO_IPV6, 127 .checkentry = dscp_tg_check, 128 .target = dscp_tg6, 129 .targetsize = sizeof(struct xt_DSCP_info), 130 .table = "mangle", 131 .me = THIS_MODULE, 132 }, 133 { 134 .name = "TOS", 135 .revision = 1, 136 .family = NFPROTO_IPV4, 137 .table = "mangle", 138 .target = tos_tg, 139 .targetsize = sizeof(struct xt_tos_target_info), 140 .me = THIS_MODULE, 141 }, 142 { 143 .name = "TOS", 144 .revision = 1, 145 .family = NFPROTO_IPV6, 146 .table = "mangle", 147 .target = tos_tg6, 148 .targetsize = sizeof(struct xt_tos_target_info), 149 .me = THIS_MODULE, 150 }, 151}; 152 153static int __init dscp_tg_init(void) 154{ 155 return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg)); 156} 157 158static void __exit dscp_tg_exit(void) 159{ 160 xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg)); 161} 162 163module_init(dscp_tg_init); 164module_exit(dscp_tg_exit); 165