1 /* Kernel module to match the bridge port in and 2 * out device for IP packets coming into contact with a bridge. */ 3 4 /* (C) 2001-2003 Bart De Schuymer <[email protected]> 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 11 #include <linux/module.h> 12 #include <linux/skbuff.h> 13 #include <linux/netfilter/xt_physdev.h> 14 #include <linux/netfilter/x_tables.h> 15 #include <linux/netfilter_bridge.h> 16 #define MATCH 1 17 #define NOMATCH 0 18 19 MODULE_LICENSE("GPL"); 20 MODULE_AUTHOR("Bart De Schuymer <[email protected]>"); 21 MODULE_DESCRIPTION("iptables bridge physical device match module"); 22 MODULE_ALIAS("ipt_physdev"); 23 MODULE_ALIAS("ip6t_physdev"); 24 25 static int 26 match(const struct sk_buff *skb, 27 const struct net_device *in, 28 const struct net_device *out, 29 const void *matchinfo, 30 int offset, 31 unsigned int protoff, 32 int *hotdrop) 33 { 34 int i; 35 static const char nulldevname[IFNAMSIZ]; 36 const struct xt_physdev_info *info = matchinfo; 37 unsigned int ret; 38 const char *indev, *outdev; 39 struct nf_bridge_info *nf_bridge; 40 41 /* Not a bridged IP packet or no info available yet: 42 * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if 43 * the destination device will be a bridge. */ 44 if (!(nf_bridge = skb->nf_bridge)) { 45 /* Return MATCH if the invert flags of the used options are on */ 46 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) && 47 !(info->invert & XT_PHYSDEV_OP_BRIDGED)) 48 return NOMATCH; 49 if ((info->bitmask & XT_PHYSDEV_OP_ISIN) && 50 !(info->invert & XT_PHYSDEV_OP_ISIN)) 51 return NOMATCH; 52 if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) && 53 !(info->invert & XT_PHYSDEV_OP_ISOUT)) 54 return NOMATCH; 55 if ((info->bitmask & XT_PHYSDEV_OP_IN) && 56 !(info->invert & XT_PHYSDEV_OP_IN)) 57 return NOMATCH; 58 if ((info->bitmask & XT_PHYSDEV_OP_OUT) && 59 !(info->invert & XT_PHYSDEV_OP_OUT)) 60 return NOMATCH; 61 return MATCH; 62 } 63 64 /* This only makes sense in the FORWARD and POSTROUTING chains */ 65 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) && 66 (!!(nf_bridge->mask & BRNF_BRIDGED) ^ 67 !(info->invert & XT_PHYSDEV_OP_BRIDGED))) 68 return NOMATCH; 69 70 if ((info->bitmask & XT_PHYSDEV_OP_ISIN && 71 (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) || 72 (info->bitmask & XT_PHYSDEV_OP_ISOUT && 73 (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT)))) 74 return NOMATCH; 75 76 if (!(info->bitmask & XT_PHYSDEV_OP_IN)) 77 goto match_outdev; 78 indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname; 79 for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) { 80 ret |= (((const unsigned int *)indev)[i] 81 ^ ((const unsigned int *)info->physindev)[i]) 82 & ((const unsigned int *)info->in_mask)[i]; 83 } 84 85 if ((ret == 0) ^ !(info->invert & XT_PHYSDEV_OP_IN)) 86 return NOMATCH; 87 88 match_outdev: 89 if (!(info->bitmask & XT_PHYSDEV_OP_OUT)) 90 return MATCH; 91 outdev = nf_bridge->physoutdev ? 92 nf_bridge->physoutdev->name : nulldevname; 93 for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) { 94 ret |= (((const unsigned int *)outdev)[i] 95 ^ ((const unsigned int *)info->physoutdev)[i]) 96 & ((const unsigned int *)info->out_mask)[i]; 97 } 98 99 return (ret != 0) ^ !(info->invert & XT_PHYSDEV_OP_OUT); 100 } 101 102 static int 103 checkentry(const char *tablename, 104 const void *ip, 105 void *matchinfo, 106 unsigned int matchsize, 107 unsigned int hook_mask) 108 { 109 const struct xt_physdev_info *info = matchinfo; 110 111 if (matchsize != XT_ALIGN(sizeof(struct xt_physdev_info))) 112 return 0; 113 if (!(info->bitmask & XT_PHYSDEV_OP_MASK) || 114 info->bitmask & ~XT_PHYSDEV_OP_MASK) 115 return 0; 116 return 1; 117 } 118 119 static struct xt_match physdev_match = { 120 .name = "physdev", 121 .match = &match, 122 .checkentry = &checkentry, 123 .me = THIS_MODULE, 124 }; 125 126 static struct xt_match physdev6_match = { 127 .name = "physdev", 128 .match = &match, 129 .checkentry = &checkentry, 130 .me = THIS_MODULE, 131 }; 132 133 static int __init init(void) 134 { 135 int ret; 136 137 ret = xt_register_match(AF_INET, &physdev_match); 138 if (ret < 0) 139 return ret; 140 141 ret = xt_register_match(AF_INET6, &physdev6_match); 142 if (ret < 0) 143 xt_unregister_match(AF_INET, &physdev_match); 144 145 return ret; 146 } 147 148 static void __exit fini(void) 149 { 150 xt_unregister_match(AF_INET, &physdev_match); 151 xt_unregister_match(AF_INET6, &physdev6_match); 152 } 153 154 module_init(init); 155 module_exit(fini); 156