projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 8f97339d FW |
1 | /* |
| 2 | * Copyright (c) 2011 Florian Westphal <fw@strlen.de> | |
| 3 | * | |
| 4 | * This program is free software; you can redistribute it and/or modify | |
| 5 | * it under the terms of the GNU General Public License version 2 as | |
| 6 | * published by the Free Software Foundation. | |
| 7 | * | |
| 8 | * based on fib_frontend.c; Author: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> | |
| 9 | */ | |
| 10 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
| 11 | #include <linux/module.h> | |
| 12 | #include <linux/skbuff.h> | |
| 13 | #include <linux/netdevice.h> | |
| 14 | #include <linux/ip.h> | |
| 15 | #include <net/ip.h> | |
| 16 | #include <net/ip_fib.h> | |
| 17 | #include <net/route.h> | |
| 18 | ||
| 19 | #include <linux/netfilter/xt_rpfilter.h> | |
| 20 | #include <linux/netfilter/x_tables.h> | |
| 21 | ||
| 22 | MODULE_LICENSE("GPL"); | |
| 23 | MODULE_AUTHOR("Florian Westphal <fw@strlen.de>"); | |
| 24 | MODULE_DESCRIPTION("iptables: ipv4 reverse path filter match"); | |
| 25 | ||
| 26 | /* don't try to find route from mcast/bcast/zeronet */ | |
| 27 | static __be32 rpfilter_get_saddr(__be32 addr) | |
| 28 | { | |
| 29 | if (ipv4_is_multicast(addr) || ipv4_is_lbcast(addr) || | |
| 30 | ipv4_is_zeronet(addr)) | |
| 31 | return 0; | |
| 32 | return addr; | |
| 33 | } | |
| 34 | ||
| 35 | static bool rpfilter_lookup_reverse(struct flowi4 *fl4, | |
| 36 | const struct net_device *dev, u8 flags) | |
| 37 | { | |
| 38 | struct fib_result res; | |
| 39 | bool dev_match; | |
| 40 | struct net *net = dev_net(dev); | |
| 41 | int ret __maybe_unused; | |
| 42 | ||
| 43 | if (fib_lookup(net, fl4, &res)) | |
| 44 | return false; | |
| 45 | ||
| 46 | if (res.type != RTN_UNICAST) { | |
| 47 | if (res.type != RTN_LOCAL || !(flags & XT_RPFILTER_ACCEPT_LOCAL)) | |
| 48 | return false; | |
| 49 | } | |
| 50 | dev_match = false; | |
| 51 | #ifdef CONFIG_IP_ROUTE_MULTIPATH | |
| 52 | for (ret = 0; ret < res.fi->fib_nhs; ret++) { | |
| 53 | struct fib_nh *nh = &res.fi->fib_nh[ret]; | |
| 54 | ||
| 55 | if (nh->nh_dev == dev) { | |
| 56 | dev_match = true; | |
| 57 | break; | |
| 58 | } | |
| 59 | } | |
| 60 | #else | |
| 61 | if (FIB_RES_DEV(res) == dev) | |
| 62 | dev_match = true; | |
| 63 | #endif | |
| 64 | if (dev_match || flags & XT_RPFILTER_LOOSE) | |
| 65 | return FIB_RES_NH(res).nh_scope <= RT_SCOPE_HOST; | |
| 66 | return dev_match; | |
| 67 | } | |
| 68 | ||
| 69 | static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par) | |
| 70 | { | |
| 71 | const struct xt_rpfilter_info *info; | |
| 72 | const struct iphdr *iph; | |
| 73 | struct flowi4 flow; | |
| 74 | bool invert; | |
| 75 | ||
| 76 | info = par->matchinfo; | |
| 77 | invert = info->flags & XT_RPFILTER_INVERT; | |
| 78 | ||
| 79 | if (par->in->flags & IFF_LOOPBACK) | |
| 80 | return true ^ invert; | |
| 81 | ||
| 82 | iph = ip_hdr(skb); | |
| 83 | if (ipv4_is_multicast(iph->daddr)) { | |
| 84 | if (ipv4_is_zeronet(iph->saddr)) | |
| 85 | return ipv4_is_local_multicast(iph->daddr) ^ invert; | |
| 86 | flow.flowi4_iif = 0; | |
| 87 | } else { | |
| 1fb9489b | 88 | flow.flowi4_iif = LOOPBACK_IFINDEX; |
| 8f97339d FW |
89 | } |
| 90 | ||
| 91 | flow.daddr = iph->saddr; | |
| 92 | flow.saddr = rpfilter_get_saddr(iph->daddr); | |
| 93 | flow.flowi4_oif = 0; | |
| 94 | flow.flowi4_mark = info->flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0; | |
| 95 | flow.flowi4_tos = RT_TOS(iph->tos); | |
| 96 | flow.flowi4_scope = RT_SCOPE_UNIVERSE; | |
| 97 | ||
| 98 | return rpfilter_lookup_reverse(&flow, par->in, info->flags) ^ invert; | |
| 99 | } | |
| 100 | ||
| 101 | static int rpfilter_check(const struct xt_mtchk_param *par) | |
| 102 | { | |
| 103 | const struct xt_rpfilter_info *info = par->matchinfo; | |
| 104 | unsigned int options = ~XT_RPFILTER_OPTION_MASK; | |
| 105 | if (info->flags & options) { | |
| 106 | pr_info("unknown options encountered"); | |
| 107 | return -EINVAL; | |
| 108 | } | |
| 109 | ||
| 110 | if (strcmp(par->table, "mangle") != 0 && | |
| 111 | strcmp(par->table, "raw") != 0) { | |
| 112 | pr_info("match only valid in the \'raw\' " | |
| 113 | "or \'mangle\' tables, not \'%s\'.\n", par->table); | |
| 114 | return -EINVAL; | |
| 115 | } | |
| 116 | ||
| 117 | return 0; | |
| 118 | } | |
| 119 | ||
| 120 | static struct xt_match rpfilter_mt_reg __read_mostly = { | |
| 121 | .name = "rpfilter", | |
| 122 | .family = NFPROTO_IPV4, | |
| 123 | .checkentry = rpfilter_check, | |
| 124 | .match = rpfilter_mt, | |
| 125 | .matchsize = sizeof(struct xt_rpfilter_info), | |
| 126 | .hooks = (1 << NF_INET_PRE_ROUTING), | |
| 127 | .me = THIS_MODULE | |
| 128 | }; | |
| 129 | ||
| 130 | static int __init rpfilter_mt_init(void) | |
| 131 | { | |
| 132 | return xt_register_match(&rpfilter_mt_reg); | |
| 133 | } | |
| 134 | ||
| 135 | static void __exit rpfilter_mt_exit(void) | |
| 136 | { | |
| 137 | xt_unregister_match(&rpfilter_mt_reg); | |
| 138 | } | |
| 139 | ||
| 140 | module_init(rpfilter_mt_init); | |
| 141 | module_exit(rpfilter_mt_exit); |