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 struct xt_match *match, 30 const void *matchinfo, 31 int offset, 32 unsigned int protoff, 33 int *hotdrop) 34 { 35 int i; 36 static const char nulldevname[IFNAMSIZ]; 37 const struct xt_physdev_info *info = matchinfo; 38 unsigned int ret; 39 const char *indev, *outdev; 40 struct nf_bridge_info *nf_bridge; 41 42 /* Not a bridged IP packet or no info available yet: 43 * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if 44 * the destination device will be a bridge. */ 45 if (!(nf_bridge = skb->nf_bridge)) { 46 /* Return MATCH if the invert flags of the used options are on */ 47 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) && 48 !(info->invert & XT_PHYSDEV_OP_BRIDGED)) 49 return NOMATCH; 50 if ((info->bitmask & XT_PHYSDEV_OP_ISIN) && 51 !(info->invert & XT_PHYSDEV_OP_ISIN)) 52 return NOMATCH; 53 if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) && 54 !(info->invert & XT_PHYSDEV_OP_ISOUT)) 55 return NOMATCH; 56 if ((info->bitmask & XT_PHYSDEV_OP_IN) && 57 !(info->invert & XT_PHYSDEV_OP_IN)) 58 return NOMATCH; 59 if ((info->bitmask & XT_PHYSDEV_OP_OUT) && 60 !(info->invert & XT_PHYSDEV_OP_OUT)) 61 return NOMATCH; 62 return MATCH; 63 } 64 65 /* This only makes sense in the FORWARD and POSTROUTING chains */ 66 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) && 67 (!!(nf_bridge->mask & BRNF_BRIDGED) ^ 68 !(info->invert & XT_PHYSDEV_OP_BRIDGED))) 69 return NOMATCH; 70 71 if ((info->bitmask & XT_PHYSDEV_OP_ISIN && 72 (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) || 73 (info->bitmask & XT_PHYSDEV_OP_ISOUT && 74 (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT)))) 75 return NOMATCH; 76 77 if (!(info->bitmask & XT_PHYSDEV_OP_IN)) 78 goto match_outdev; 79 indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname; 80 for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) { 81 ret |= (((const unsigned int *)indev)[i] 82 ^ ((const unsigned int *)info->physindev)[i]) 83 & ((const unsigned int *)info->in_mask)[i]; 84 } 85 86 if ((ret == 0) ^ !(info->invert & XT_PHYSDEV_OP_IN)) 87 return NOMATCH; 88 89 match_outdev: 90 if (!(info->bitmask & XT_PHYSDEV_OP_OUT)) 91 return MATCH; 92 outdev = nf_bridge->physoutdev ? 93 nf_bridge->physoutdev->name : nulldevname; 94 for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) { 95 ret |= (((const unsigned int *)outdev)[i] 96 ^ ((const unsigned int *)info->physoutdev)[i]) 97 & ((const unsigned int *)info->out_mask)[i]; 98 } 99 100 return (ret != 0) ^ !(info->invert & XT_PHYSDEV_OP_OUT); 101 } 102 103 static int 104 checkentry(const char *tablename, 105 const void *ip, 106 const struct xt_match *match, 107 void *matchinfo, 108 unsigned int matchsize, 109 unsigned int hook_mask) 110 { 111 const struct xt_physdev_info *info = matchinfo; 112 113 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 .matchsize = sizeof(struct xt_physdev_info), 123 .checkentry = checkentry, 124 .family = AF_INET, 125 .me = THIS_MODULE, 126 }; 127 128 static struct xt_match physdev6_match = { 129 .name = "physdev", 130 .match = match, 131 .matchsize = sizeof(struct xt_physdev_info), 132 .checkentry = checkentry, 133 .family = AF_INET6, 134 .me = THIS_MODULE, 135 }; 136 137 static int __init xt_physdev_init(void) 138 { 139 int ret; 140 141 ret = xt_register_match(&physdev_match); 142 if (ret < 0) 143 return ret; 144 145 ret = xt_register_match(&physdev6_match); 146 if (ret < 0) 147 xt_unregister_match(&physdev_match); 148 149 return ret; 150 } 151 152 static void __exit xt_physdev_fini(void) 153 { 154 xt_unregister_match(&physdev_match); 155 xt_unregister_match(&physdev6_match); 156 } 157 158 module_init(xt_physdev_init); 159 module_exit(xt_physdev_fini); 160