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 bool r; 29 pr_debug("segsleft_match:%c 0x%x <= 0x%x <= 0x%x\n", 30 invert ? '!' : ' ', min, id, max); 31 r = (id >= min && id <= max) ^ invert; 32 pr_debug(" result %s\n", r ? "PASS" : "FAILED"); 33 return r; 34 } 35 36 static bool rt_mt6(const struct sk_buff *skb, struct xt_action_param *par) 37 { 38 struct ipv6_rt_hdr _route; 39 const struct ipv6_rt_hdr *rh; 40 const struct ip6t_rt *rtinfo = par->matchinfo; 41 unsigned int temp; 42 unsigned int ptr = 0; 43 unsigned int hdrlen = 0; 44 bool ret = false; 45 struct in6_addr _addr; 46 const struct in6_addr *ap; 47 int err; 48 49 err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL, NULL); 50 if (err < 0) { 51 if (err != -ENOENT) 52 par->hotdrop = true; 53 return false; 54 } 55 56 rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route); 57 if (rh == NULL) { 58 par->hotdrop = true; 59 return false; 60 } 61 62 hdrlen = ipv6_optlen(rh); 63 if (skb->len - ptr < hdrlen) { 64 /* Pcket smaller than its length field */ 65 return false; 66 } 67 68 pr_debug("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen); 69 pr_debug("TYPE %04X ", rh->type); 70 pr_debug("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left); 71 72 pr_debug("IPv6 RT segsleft %02X ", 73 segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1], 74 rh->segments_left, 75 !!(rtinfo->invflags & IP6T_RT_INV_SGS))); 76 pr_debug("type %02X %02X %02X ", 77 rtinfo->rt_type, rh->type, 78 (!(rtinfo->flags & IP6T_RT_TYP) || 79 ((rtinfo->rt_type == rh->type) ^ 80 !!(rtinfo->invflags & IP6T_RT_INV_TYP)))); 81 pr_debug("len %02X %04X %02X ", 82 rtinfo->hdrlen, hdrlen, 83 !(rtinfo->flags & IP6T_RT_LEN) || 84 ((rtinfo->hdrlen == hdrlen) ^ 85 !!(rtinfo->invflags & IP6T_RT_INV_LEN))); 86 pr_debug("res %02X %02X %02X ", 87 rtinfo->flags & IP6T_RT_RES, 88 ((const struct rt0_hdr *)rh)->reserved, 89 !((rtinfo->flags & IP6T_RT_RES) && 90 (((const struct rt0_hdr *)rh)->reserved))); 91 92 ret = (rh != NULL) && 93 (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1], 94 rh->segments_left, 95 !!(rtinfo->invflags & IP6T_RT_INV_SGS))) && 96 (!(rtinfo->flags & IP6T_RT_LEN) || 97 ((rtinfo->hdrlen == hdrlen) ^ 98 !!(rtinfo->invflags & IP6T_RT_INV_LEN))) && 99 (!(rtinfo->flags & IP6T_RT_TYP) || 100 ((rtinfo->rt_type == rh->type) ^ 101 !!(rtinfo->invflags & IP6T_RT_INV_TYP))); 102 103 if (ret && (rtinfo->flags & IP6T_RT_RES)) { 104 const u_int32_t *rp; 105 u_int32_t _reserved; 106 rp = skb_header_pointer(skb, 107 ptr + offsetof(struct rt0_hdr, 108 reserved), 109 sizeof(_reserved), 110 &_reserved); 111 112 ret = (*rp == 0); 113 } 114 115 pr_debug("#%d ", rtinfo->addrnr); 116 if (!(rtinfo->flags & IP6T_RT_FST)) { 117 return ret; 118 } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) { 119 pr_debug("Not strict "); 120 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) { 121 pr_debug("There isn't enough space\n"); 122 return false; 123 } else { 124 unsigned int i = 0; 125 126 pr_debug("#%d ", rtinfo->addrnr); 127 for (temp = 0; 128 temp < (unsigned int)((hdrlen - 8) / 16); 129 temp++) { 130 ap = skb_header_pointer(skb, 131 ptr 132 + sizeof(struct rt0_hdr) 133 + temp * sizeof(_addr), 134 sizeof(_addr), 135 &_addr); 136 137 if (ap == NULL) { 138 par->hotdrop = true; 139 return false; 140 } 141 142 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) { 143 pr_debug("i=%d temp=%d;\n", i, temp); 144 i++; 145 } 146 if (i == rtinfo->addrnr) 147 break; 148 } 149 pr_debug("i=%d #%d\n", i, rtinfo->addrnr); 150 if (i == rtinfo->addrnr) 151 return ret; 152 else 153 return false; 154 } 155 } else { 156 pr_debug("Strict "); 157 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) { 158 pr_debug("There isn't enough space\n"); 159 return false; 160 } else { 161 pr_debug("#%d ", rtinfo->addrnr); 162 for (temp = 0; temp < rtinfo->addrnr; temp++) { 163 ap = skb_header_pointer(skb, 164 ptr 165 + sizeof(struct rt0_hdr) 166 + temp * sizeof(_addr), 167 sizeof(_addr), 168 &_addr); 169 if (ap == NULL) { 170 par->hotdrop = true; 171 return false; 172 } 173 174 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp])) 175 break; 176 } 177 pr_debug("temp=%d #%d\n", temp, rtinfo->addrnr); 178 if (temp == rtinfo->addrnr && 179 temp == (unsigned int)((hdrlen - 8) / 16)) 180 return ret; 181 else 182 return false; 183 } 184 } 185 186 return false; 187 } 188 189 static int rt_mt6_check(const struct xt_mtchk_param *par) 190 { 191 const struct ip6t_rt *rtinfo = par->matchinfo; 192 193 if (rtinfo->invflags & ~IP6T_RT_INV_MASK) { 194 pr_debug("unknown flags %X\n", rtinfo->invflags); 195 return -EINVAL; 196 } 197 if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) && 198 (!(rtinfo->flags & IP6T_RT_TYP) || 199 (rtinfo->rt_type != 0) || 200 (rtinfo->invflags & IP6T_RT_INV_TYP))) { 201 pr_debug("`--rt-type 0' required before `--rt-0-*'"); 202 return -EINVAL; 203 } 204 205 return 0; 206 } 207 208 static struct xt_match rt_mt6_reg __read_mostly = { 209 .name = "rt", 210 .family = NFPROTO_IPV6, 211 .match = rt_mt6, 212 .matchsize = sizeof(struct ip6t_rt), 213 .checkentry = rt_mt6_check, 214 .me = THIS_MODULE, 215 }; 216 217 static int __init rt_mt6_init(void) 218 { 219 return xt_register_match(&rt_mt6_reg); 220 } 221 222 static void __exit rt_mt6_exit(void) 223 { 224 xt_unregister_match(&rt_mt6_reg); 225 } 226 227 module_init(rt_mt6_init); 228 module_exit(rt_mt6_exit); 229