1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Kernel module to match the bridge port in and 3 * out device for IP packets coming into contact with a bridge. */ 4 5 /* (C) 2001-2003 Bart De Schuymer <bdschuym@pandora.be> 6 */ 7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 8 9 #include <linux/if.h> 10 #include <linux/module.h> 11 #include <linux/skbuff.h> 12 #include <linux/netfilter_bridge.h> 13 #include <linux/netfilter/x_tables.h> 14 #include <uapi/linux/netfilter/xt_physdev.h> 15 16 MODULE_LICENSE("GPL"); 17 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>"); 18 MODULE_DESCRIPTION("Xtables: Bridge physical device match"); 19 MODULE_ALIAS("ipt_physdev"); 20 MODULE_ALIAS("ip6t_physdev"); 21 22 23 static bool 24 physdev_mt(const struct sk_buff *skb, struct xt_action_param *par) 25 { 26 const struct xt_physdev_info *info = par->matchinfo; 27 const struct net_device *physdev; 28 unsigned long ret; 29 const char *indev, *outdev; 30 31 /* Not a bridged IP packet or no info available yet: 32 * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if 33 * the destination device will be a bridge. */ 34 if (!nf_bridge_info_exists(skb)) { 35 /* Return MATCH if the invert flags of the used options are on */ 36 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) && 37 !(info->invert & XT_PHYSDEV_OP_BRIDGED)) 38 return false; 39 if ((info->bitmask & XT_PHYSDEV_OP_ISIN) && 40 !(info->invert & XT_PHYSDEV_OP_ISIN)) 41 return false; 42 if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) && 43 !(info->invert & XT_PHYSDEV_OP_ISOUT)) 44 return false; 45 if ((info->bitmask & XT_PHYSDEV_OP_IN) && 46 !(info->invert & XT_PHYSDEV_OP_IN)) 47 return false; 48 if ((info->bitmask & XT_PHYSDEV_OP_OUT) && 49 !(info->invert & XT_PHYSDEV_OP_OUT)) 50 return false; 51 return true; 52 } 53 54 physdev = nf_bridge_get_physoutdev(skb); 55 outdev = physdev ? physdev->name : NULL; 56 57 /* This only makes sense in the FORWARD and POSTROUTING chains */ 58 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) && 59 (!!outdev ^ !(info->invert & XT_PHYSDEV_OP_BRIDGED))) 60 return false; 61 62 physdev = nf_bridge_get_physindev(skb); 63 indev = physdev ? physdev->name : NULL; 64 65 if ((info->bitmask & XT_PHYSDEV_OP_ISIN && 66 (!indev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) || 67 (info->bitmask & XT_PHYSDEV_OP_ISOUT && 68 (!outdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT)))) 69 return false; 70 71 if (!(info->bitmask & XT_PHYSDEV_OP_IN)) 72 goto match_outdev; 73 74 if (indev) { 75 ret = ifname_compare_aligned(indev, info->physindev, 76 info->in_mask); 77 78 if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN)) 79 return false; 80 } 81 82 match_outdev: 83 if (!(info->bitmask & XT_PHYSDEV_OP_OUT)) 84 return true; 85 86 if (!outdev) 87 return false; 88 89 ret = ifname_compare_aligned(outdev, info->physoutdev, info->out_mask); 90 91 return (!!ret ^ !(info->invert & XT_PHYSDEV_OP_OUT)); 92 } 93 94 static int physdev_mt_check(const struct xt_mtchk_param *par) 95 { 96 const struct xt_physdev_info *info = par->matchinfo; 97 static bool brnf_probed __read_mostly; 98 99 if (!(info->bitmask & XT_PHYSDEV_OP_MASK) || 100 info->bitmask & ~XT_PHYSDEV_OP_MASK) 101 return -EINVAL; 102 if (info->bitmask & (XT_PHYSDEV_OP_OUT | XT_PHYSDEV_OP_ISOUT) && 103 (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) || 104 info->invert & XT_PHYSDEV_OP_BRIDGED) && 105 par->hook_mask & (1 << NF_INET_LOCAL_OUT)) { 106 pr_info_ratelimited("--physdev-out and --physdev-is-out only supported in the FORWARD and POSTROUTING chains with bridged traffic\n"); 107 return -EINVAL; 108 } 109 110 if (!brnf_probed) { 111 brnf_probed = true; 112 request_module("br_netfilter"); 113 } 114 115 return 0; 116 } 117 118 static struct xt_match physdev_mt_reg __read_mostly = { 119 .name = "physdev", 120 .revision = 0, 121 .family = NFPROTO_UNSPEC, 122 .checkentry = physdev_mt_check, 123 .match = physdev_mt, 124 .matchsize = sizeof(struct xt_physdev_info), 125 .me = THIS_MODULE, 126 }; 127 128 static int __init physdev_mt_init(void) 129 { 130 return xt_register_match(&physdev_mt_reg); 131 } 132 133 static void __exit physdev_mt_exit(void) 134 { 135 xt_unregister_match(&physdev_mt_reg); 136 } 137 138 module_init(physdev_mt_init); 139 module_exit(physdev_mt_exit); 140