1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Kernel module to match ROUTING parameters. */ 3 4 /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> 5 */ 6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 7 #include <linux/module.h> 8 #include <linux/skbuff.h> 9 #include <linux/ipv6.h> 10 #include <linux/types.h> 11 #include <net/checksum.h> 12 #include <net/ipv6.h> 13 14 #include <asm/byteorder.h> 15 16 #include <linux/netfilter/x_tables.h> 17 #include <linux/netfilter_ipv6/ip6_tables.h> 18 #include <linux/netfilter_ipv6/ip6t_rt.h> 19 20 MODULE_LICENSE("GPL"); 21 MODULE_DESCRIPTION("Xtables: IPv6 Routing Header match"); 22 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); 23 24 /* Returns 1 if the id is matched by the range, 0 otherwise */ 25 static inline bool 26 segsleft_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert) 27 { 28 return (id >= min && id <= max) ^ invert; 29 } 30 31 static bool rt_mt6(const struct sk_buff *skb, struct xt_action_param *par) 32 { 33 struct ipv6_rt_hdr _route; 34 const struct ipv6_rt_hdr *rh; 35 const struct ip6t_rt *rtinfo = par->matchinfo; 36 unsigned int temp; 37 unsigned int ptr = 0; 38 unsigned int hdrlen = 0; 39 bool ret = false; 40 struct in6_addr _addr; 41 const struct in6_addr *ap; 42 int err; 43 44 err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL, NULL); 45 if (err < 0) { 46 if (err != -ENOENT) 47 par->hotdrop = true; 48 return false; 49 } 50 51 rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route); 52 if (rh == NULL) { 53 par->hotdrop = true; 54 return false; 55 } 56 57 hdrlen = ipv6_optlen(rh); 58 if (skb->len - ptr < hdrlen) { 59 /* Pcket smaller than its length field */ 60 return false; 61 } 62 63 ret = (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1], 64 rh->segments_left, 65 !!(rtinfo->invflags & IP6T_RT_INV_SGS))) && 66 (!(rtinfo->flags & IP6T_RT_LEN) || 67 ((rtinfo->hdrlen == hdrlen) ^ 68 !!(rtinfo->invflags & IP6T_RT_INV_LEN))) && 69 (!(rtinfo->flags & IP6T_RT_TYP) || 70 ((rtinfo->rt_type == rh->type) ^ 71 !!(rtinfo->invflags & IP6T_RT_INV_TYP))); 72 73 if (ret && (rtinfo->flags & IP6T_RT_RES)) { 74 const u_int32_t *rp; 75 u_int32_t _reserved; 76 rp = skb_header_pointer(skb, 77 ptr + offsetof(struct rt0_hdr, 78 reserved), 79 sizeof(_reserved), 80 &_reserved); 81 if (!rp) { 82 par->hotdrop = true; 83 return false; 84 } 85 86 ret = (*rp == 0); 87 } 88 89 if (!(rtinfo->flags & IP6T_RT_FST)) { 90 return ret; 91 } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) { 92 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) { 93 return false; 94 } else { 95 unsigned int i = 0; 96 97 for (temp = 0; 98 temp < (unsigned int)((hdrlen - 8) / 16); 99 temp++) { 100 ap = skb_header_pointer(skb, 101 ptr 102 + sizeof(struct rt0_hdr) 103 + temp * sizeof(_addr), 104 sizeof(_addr), 105 &_addr); 106 107 if (ap == NULL) { 108 par->hotdrop = true; 109 return false; 110 } 111 112 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) 113 i++; 114 if (i == rtinfo->addrnr) 115 break; 116 } 117 if (i == rtinfo->addrnr) 118 return ret; 119 else 120 return false; 121 } 122 } else { 123 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) { 124 return false; 125 } else { 126 for (temp = 0; temp < rtinfo->addrnr; temp++) { 127 ap = skb_header_pointer(skb, 128 ptr 129 + sizeof(struct rt0_hdr) 130 + temp * sizeof(_addr), 131 sizeof(_addr), 132 &_addr); 133 if (ap == NULL) { 134 par->hotdrop = true; 135 return false; 136 } 137 138 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp])) 139 break; 140 } 141 if (temp == rtinfo->addrnr && 142 temp == (unsigned int)((hdrlen - 8) / 16)) 143 return ret; 144 else 145 return false; 146 } 147 } 148 149 return false; 150 } 151 152 static int rt_mt6_check(const struct xt_mtchk_param *par) 153 { 154 const struct ip6t_rt *rtinfo = par->matchinfo; 155 156 if (rtinfo->invflags & ~IP6T_RT_INV_MASK) { 157 pr_debug("unknown flags %X\n", rtinfo->invflags); 158 return -EINVAL; 159 } 160 if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) && 161 (!(rtinfo->flags & IP6T_RT_TYP) || 162 (rtinfo->rt_type != 0) || 163 (rtinfo->invflags & IP6T_RT_INV_TYP))) { 164 pr_debug("`--rt-type 0' required before `--rt-0-*'"); 165 return -EINVAL; 166 } 167 168 return 0; 169 } 170 171 static struct xt_match rt_mt6_reg __read_mostly = { 172 .name = "rt", 173 .family = NFPROTO_IPV6, 174 .match = rt_mt6, 175 .matchsize = sizeof(struct ip6t_rt), 176 .checkentry = rt_mt6_check, 177 .me = THIS_MODULE, 178 }; 179 180 static int __init rt_mt6_init(void) 181 { 182 return xt_register_match(&rt_mt6_reg); 183 } 184 185 static void __exit rt_mt6_exit(void) 186 { 187 xt_unregister_match(&rt_mt6_reg); 188 } 189 190 module_init(rt_mt6_init); 191 module_exit(rt_mt6_exit); 192