1 /* Kernel module to match ROUTING parameters. */ 2 3 /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 */ 9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 10 #include <linux/module.h> 11 #include <linux/skbuff.h> 12 #include <linux/ipv6.h> 13 #include <linux/types.h> 14 #include <net/checksum.h> 15 #include <net/ipv6.h> 16 17 #include <asm/byteorder.h> 18 19 #include <linux/netfilter/x_tables.h> 20 #include <linux/netfilter_ipv6/ip6_tables.h> 21 #include <linux/netfilter_ipv6/ip6t_rt.h> 22 23 MODULE_LICENSE("GPL"); 24 MODULE_DESCRIPTION("Xtables: IPv6 Routing Header match"); 25 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); 26 27 /* Returns 1 if the id is matched by the range, 0 otherwise */ 28 static inline bool 29 segsleft_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert) 30 { 31 bool r; 32 pr_debug("segsleft_match:%c 0x%x <= 0x%x <= 0x%x\n", 33 invert ? '!' : ' ', min, id, max); 34 r = (id >= min && id <= max) ^ invert; 35 pr_debug(" result %s\n", r ? "PASS" : "FAILED"); 36 return r; 37 } 38 39 static bool rt_mt6(const struct sk_buff *skb, struct xt_action_param *par) 40 { 41 struct ipv6_rt_hdr _route; 42 const struct ipv6_rt_hdr *rh; 43 const struct ip6t_rt *rtinfo = par->matchinfo; 44 unsigned int temp; 45 unsigned int ptr = 0; 46 unsigned int hdrlen = 0; 47 bool ret = false; 48 struct in6_addr _addr; 49 const struct in6_addr *ap; 50 int err; 51 52 err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL, NULL); 53 if (err < 0) { 54 if (err != -ENOENT) 55 par->hotdrop = true; 56 return false; 57 } 58 59 rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route); 60 if (rh == NULL) { 61 par->hotdrop = true; 62 return false; 63 } 64 65 hdrlen = ipv6_optlen(rh); 66 if (skb->len - ptr < hdrlen) { 67 /* Pcket smaller than its length field */ 68 return false; 69 } 70 71 pr_debug("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen); 72 pr_debug("TYPE %04X ", rh->type); 73 pr_debug("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left); 74 75 pr_debug("IPv6 RT segsleft %02X ", 76 segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1], 77 rh->segments_left, 78 !!(rtinfo->invflags & IP6T_RT_INV_SGS))); 79 pr_debug("type %02X %02X %02X ", 80 rtinfo->rt_type, rh->type, 81 (!(rtinfo->flags & IP6T_RT_TYP) || 82 ((rtinfo->rt_type == rh->type) ^ 83 !!(rtinfo->invflags & IP6T_RT_INV_TYP)))); 84 pr_debug("len %02X %04X %02X ", 85 rtinfo->hdrlen, hdrlen, 86 !(rtinfo->flags & IP6T_RT_LEN) || 87 ((rtinfo->hdrlen == hdrlen) ^ 88 !!(rtinfo->invflags & IP6T_RT_INV_LEN))); 89 pr_debug("res %02X %02X %02X ", 90 rtinfo->flags & IP6T_RT_RES, 91 ((const struct rt0_hdr *)rh)->reserved, 92 !((rtinfo->flags & IP6T_RT_RES) && 93 (((const struct rt0_hdr *)rh)->reserved))); 94 95 ret = (rh != NULL) && 96 (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1], 97 rh->segments_left, 98 !!(rtinfo->invflags & IP6T_RT_INV_SGS))) && 99 (!(rtinfo->flags & IP6T_RT_LEN) || 100 ((rtinfo->hdrlen == hdrlen) ^ 101 !!(rtinfo->invflags & IP6T_RT_INV_LEN))) && 102 (!(rtinfo->flags & IP6T_RT_TYP) || 103 ((rtinfo->rt_type == rh->type) ^ 104 !!(rtinfo->invflags & IP6T_RT_INV_TYP))); 105 106 if (ret && (rtinfo->flags & IP6T_RT_RES)) { 107 const u_int32_t *rp; 108 u_int32_t _reserved; 109 rp = skb_header_pointer(skb, 110 ptr + offsetof(struct rt0_hdr, 111 reserved), 112 sizeof(_reserved), 113 &_reserved); 114 115 ret = (*rp == 0); 116 } 117 118 pr_debug("#%d ", rtinfo->addrnr); 119 if (!(rtinfo->flags & IP6T_RT_FST)) { 120 return ret; 121 } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) { 122 pr_debug("Not strict "); 123 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) { 124 pr_debug("There isn't enough space\n"); 125 return false; 126 } else { 127 unsigned int i = 0; 128 129 pr_debug("#%d ", rtinfo->addrnr); 130 for (temp = 0; 131 temp < (unsigned int)((hdrlen - 8) / 16); 132 temp++) { 133 ap = skb_header_pointer(skb, 134 ptr 135 + sizeof(struct rt0_hdr) 136 + temp * sizeof(_addr), 137 sizeof(_addr), 138 &_addr); 139 140 if (ap == NULL) { 141 par->hotdrop = true; 142 return false; 143 } 144 145 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) { 146 pr_debug("i=%d temp=%d;\n", i, temp); 147 i++; 148 } 149 if (i == rtinfo->addrnr) 150 break; 151 } 152 pr_debug("i=%d #%d\n", i, rtinfo->addrnr); 153 if (i == rtinfo->addrnr) 154 return ret; 155 else 156 return false; 157 } 158 } else { 159 pr_debug("Strict "); 160 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) { 161 pr_debug("There isn't enough space\n"); 162 return false; 163 } else { 164 pr_debug("#%d ", rtinfo->addrnr); 165 for (temp = 0; temp < rtinfo->addrnr; temp++) { 166 ap = skb_header_pointer(skb, 167 ptr 168 + sizeof(struct rt0_hdr) 169 + temp * sizeof(_addr), 170 sizeof(_addr), 171 &_addr); 172 if (ap == NULL) { 173 par->hotdrop = true; 174 return false; 175 } 176 177 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp])) 178 break; 179 } 180 pr_debug("temp=%d #%d\n", temp, rtinfo->addrnr); 181 if (temp == rtinfo->addrnr && 182 temp == (unsigned int)((hdrlen - 8) / 16)) 183 return ret; 184 else 185 return false; 186 } 187 } 188 189 return false; 190 } 191 192 static int rt_mt6_check(const struct xt_mtchk_param *par) 193 { 194 const struct ip6t_rt *rtinfo = par->matchinfo; 195 196 if (rtinfo->invflags & ~IP6T_RT_INV_MASK) { 197 pr_debug("unknown flags %X\n", rtinfo->invflags); 198 return -EINVAL; 199 } 200 if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) && 201 (!(rtinfo->flags & IP6T_RT_TYP) || 202 (rtinfo->rt_type != 0) || 203 (rtinfo->invflags & IP6T_RT_INV_TYP))) { 204 pr_debug("`--rt-type 0' required before `--rt-0-*'"); 205 return -EINVAL; 206 } 207 208 return 0; 209 } 210 211 static struct xt_match rt_mt6_reg __read_mostly = { 212 .name = "rt", 213 .family = NFPROTO_IPV6, 214 .match = rt_mt6, 215 .matchsize = sizeof(struct ip6t_rt), 216 .checkentry = rt_mt6_check, 217 .me = THIS_MODULE, 218 }; 219 220 static int __init rt_mt6_init(void) 221 { 222 return xt_register_match(&rt_mt6_reg); 223 } 224 225 static void __exit rt_mt6_exit(void) 226 { 227 xt_unregister_match(&rt_mt6_reg); 228 } 229 230 module_init(rt_mt6_init); 231 module_exit(rt_mt6_exit); 232