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 22 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); 23 MODULE_DESCRIPTION("Xtables: DSCP/TOS field modification"); 24 MODULE_LICENSE("GPL"); 25 MODULE_ALIAS("ipt_DSCP"); 26 MODULE_ALIAS("ip6t_DSCP"); 27 MODULE_ALIAS("ipt_TOS"); 28 MODULE_ALIAS("ip6t_TOS"); 29 30 static unsigned int 31 dscp_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), 41 (__force __u8)(~XT_DSCP_MASK), 42 dinfo->dscp << XT_DSCP_SHIFT); 43 44 } 45 return XT_CONTINUE; 46 } 47 48 static unsigned int 49 dscp_tg6(struct sk_buff *skb, const struct xt_action_param *par) 50 { 51 const struct xt_DSCP_info *dinfo = par->targinfo; 52 u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT; 53 54 if (dscp != dinfo->dscp) { 55 if (!skb_make_writable(skb, sizeof(struct ipv6hdr))) 56 return NF_DROP; 57 58 ipv6_change_dsfield(ipv6_hdr(skb), 59 (__force __u8)(~XT_DSCP_MASK), 60 dinfo->dscp << XT_DSCP_SHIFT); 61 } 62 return XT_CONTINUE; 63 } 64 65 static int dscp_tg_check(const struct xt_tgchk_param *par) 66 { 67 const struct xt_DSCP_info *info = par->targinfo; 68 69 if (info->dscp > XT_DSCP_MAX) { 70 pr_info("dscp %x out of range\n", info->dscp); 71 return -EDOM; 72 } 73 return 0; 74 } 75 76 static unsigned int 77 tos_tg(struct sk_buff *skb, const struct xt_action_param *par) 78 { 79 const struct xt_tos_target_info *info = par->targinfo; 80 struct iphdr *iph = ip_hdr(skb); 81 u_int8_t orig, nv; 82 83 orig = ipv4_get_dsfield(iph); 84 nv = (orig & ~info->tos_mask) ^ info->tos_value; 85 86 if (orig != nv) { 87 if (!skb_make_writable(skb, sizeof(struct iphdr))) 88 return NF_DROP; 89 iph = ip_hdr(skb); 90 ipv4_change_dsfield(iph, 0, nv); 91 } 92 93 return XT_CONTINUE; 94 } 95 96 static unsigned int 97 tos_tg6(struct sk_buff *skb, const struct xt_action_param *par) 98 { 99 const struct xt_tos_target_info *info = par->targinfo; 100 struct ipv6hdr *iph = ipv6_hdr(skb); 101 u_int8_t orig, nv; 102 103 orig = ipv6_get_dsfield(iph); 104 nv = (orig & ~info->tos_mask) ^ info->tos_value; 105 106 if (orig != nv) { 107 if (!skb_make_writable(skb, sizeof(struct iphdr))) 108 return NF_DROP; 109 iph = ipv6_hdr(skb); 110 ipv6_change_dsfield(iph, 0, nv); 111 } 112 113 return XT_CONTINUE; 114 } 115 116 static struct xt_target dscp_tg_reg[] __read_mostly = { 117 { 118 .name = "DSCP", 119 .family = NFPROTO_IPV4, 120 .checkentry = dscp_tg_check, 121 .target = dscp_tg, 122 .targetsize = sizeof(struct xt_DSCP_info), 123 .table = "mangle", 124 .me = THIS_MODULE, 125 }, 126 { 127 .name = "DSCP", 128 .family = NFPROTO_IPV6, 129 .checkentry = dscp_tg_check, 130 .target = dscp_tg6, 131 .targetsize = sizeof(struct xt_DSCP_info), 132 .table = "mangle", 133 .me = THIS_MODULE, 134 }, 135 { 136 .name = "TOS", 137 .revision = 1, 138 .family = NFPROTO_IPV4, 139 .table = "mangle", 140 .target = tos_tg, 141 .targetsize = sizeof(struct xt_tos_target_info), 142 .me = THIS_MODULE, 143 }, 144 { 145 .name = "TOS", 146 .revision = 1, 147 .family = NFPROTO_IPV6, 148 .table = "mangle", 149 .target = tos_tg6, 150 .targetsize = sizeof(struct xt_tos_target_info), 151 .me = THIS_MODULE, 152 }, 153 }; 154 155 static int __init dscp_tg_init(void) 156 { 157 return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg)); 158 } 159 160 static void __exit dscp_tg_exit(void) 161 { 162 xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg)); 163 } 164 165 module_init(dscp_tg_init); 166 module_exit(dscp_tg_exit); 167