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_bridge.h> 14 #include <linux/netfilter/xt_physdev.h> 15 #include <linux/netfilter/x_tables.h> 16 17 MODULE_LICENSE("GPL"); 18 MODULE_AUTHOR("Bart De Schuymer <[email protected]>"); 19 MODULE_DESCRIPTION("Xtables: Bridge physical device match"); 20 MODULE_ALIAS("ipt_physdev"); 21 MODULE_ALIAS("ip6t_physdev"); 22 23 static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask) 24 { 25 const unsigned long *a = (const unsigned long *)_a; 26 const unsigned long *b = (const unsigned long *)_b; 27 const unsigned long *mask = (const unsigned long *)_mask; 28 unsigned long ret; 29 30 ret = (a[0] ^ b[0]) & mask[0]; 31 if (IFNAMSIZ > sizeof(unsigned long)) 32 ret |= (a[1] ^ b[1]) & mask[1]; 33 if (IFNAMSIZ > 2 * sizeof(unsigned long)) 34 ret |= (a[2] ^ b[2]) & mask[2]; 35 if (IFNAMSIZ > 3 * sizeof(unsigned long)) 36 ret |= (a[3] ^ b[3]) & mask[3]; 37 BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long)); 38 return ret; 39 } 40 41 static bool 42 physdev_mt(const struct sk_buff *skb, const struct xt_match_param *par) 43 { 44 static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long)))); 45 const struct xt_physdev_info *info = par->matchinfo; 46 unsigned long ret; 47 const char *indev, *outdev; 48 const struct nf_bridge_info *nf_bridge; 49 50 /* Not a bridged IP packet or no info available yet: 51 * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if 52 * the destination device will be a bridge. */ 53 if (!(nf_bridge = skb->nf_bridge)) { 54 /* Return MATCH if the invert flags of the used options are on */ 55 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) && 56 !(info->invert & XT_PHYSDEV_OP_BRIDGED)) 57 return false; 58 if ((info->bitmask & XT_PHYSDEV_OP_ISIN) && 59 !(info->invert & XT_PHYSDEV_OP_ISIN)) 60 return false; 61 if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) && 62 !(info->invert & XT_PHYSDEV_OP_ISOUT)) 63 return false; 64 if ((info->bitmask & XT_PHYSDEV_OP_IN) && 65 !(info->invert & XT_PHYSDEV_OP_IN)) 66 return false; 67 if ((info->bitmask & XT_PHYSDEV_OP_OUT) && 68 !(info->invert & XT_PHYSDEV_OP_OUT)) 69 return false; 70 return true; 71 } 72 73 /* This only makes sense in the FORWARD and POSTROUTING chains */ 74 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) && 75 (!!(nf_bridge->mask & BRNF_BRIDGED) ^ 76 !(info->invert & XT_PHYSDEV_OP_BRIDGED))) 77 return false; 78 79 if ((info->bitmask & XT_PHYSDEV_OP_ISIN && 80 (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) || 81 (info->bitmask & XT_PHYSDEV_OP_ISOUT && 82 (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT)))) 83 return false; 84 85 if (!(info->bitmask & XT_PHYSDEV_OP_IN)) 86 goto match_outdev; 87 indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname; 88 ret = ifname_compare(indev, info->physindev, info->in_mask); 89 90 if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN)) 91 return false; 92 93 match_outdev: 94 if (!(info->bitmask & XT_PHYSDEV_OP_OUT)) 95 return true; 96 outdev = nf_bridge->physoutdev ? 97 nf_bridge->physoutdev->name : nulldevname; 98 ret = ifname_compare(outdev, info->physoutdev, info->out_mask); 99 100 return (!!ret ^ !(info->invert & XT_PHYSDEV_OP_OUT)); 101 } 102 103 static bool physdev_mt_check(const struct xt_mtchk_param *par) 104 { 105 const struct xt_physdev_info *info = par->matchinfo; 106 107 if (!(info->bitmask & XT_PHYSDEV_OP_MASK) || 108 info->bitmask & ~XT_PHYSDEV_OP_MASK) 109 return false; 110 if (info->bitmask & XT_PHYSDEV_OP_OUT && 111 (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) || 112 info->invert & XT_PHYSDEV_OP_BRIDGED) && 113 par->hook_mask & ((1 << NF_INET_LOCAL_OUT) | 114 (1 << NF_INET_FORWARD) | (1 << NF_INET_POST_ROUTING))) { 115 printk(KERN_WARNING "physdev match: using --physdev-out in the " 116 "OUTPUT, FORWARD and POSTROUTING chains for non-bridged " 117 "traffic is not supported anymore.\n"); 118 if (par->hook_mask & (1 << NF_INET_LOCAL_OUT)) 119 return false; 120 } 121 return true; 122 } 123 124 static struct xt_match physdev_mt_reg __read_mostly = { 125 .name = "physdev", 126 .revision = 0, 127 .family = NFPROTO_UNSPEC, 128 .checkentry = physdev_mt_check, 129 .match = physdev_mt, 130 .matchsize = sizeof(struct xt_physdev_info), 131 .me = THIS_MODULE, 132 }; 133 134 static int __init physdev_mt_init(void) 135 { 136 return xt_register_match(&physdev_mt_reg); 137 } 138 139 static void __exit physdev_mt_exit(void) 140 { 141 xt_unregister_match(&physdev_mt_reg); 142 } 143 144 module_init(physdev_mt_init); 145 module_exit(physdev_mt_exit); 146