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 = (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1], 93 rh->segments_left, 94 !!(rtinfo->invflags & IP6T_RT_INV_SGS))) && 95 (!(rtinfo->flags & IP6T_RT_LEN) || 96 ((rtinfo->hdrlen == hdrlen) ^ 97 !!(rtinfo->invflags & IP6T_RT_INV_LEN))) && 98 (!(rtinfo->flags & IP6T_RT_TYP) || 99 ((rtinfo->rt_type == rh->type) ^ 100 !!(rtinfo->invflags & IP6T_RT_INV_TYP))); 101 102 if (ret && (rtinfo->flags & IP6T_RT_RES)) { 103 const u_int32_t *rp; 104 u_int32_t _reserved; 105 rp = skb_header_pointer(skb, 106 ptr + offsetof(struct rt0_hdr, 107 reserved), 108 sizeof(_reserved), 109 &_reserved); 110 111 ret = (*rp == 0); 112 } 113 114 pr_debug("#%d ", rtinfo->addrnr); 115 if (!(rtinfo->flags & IP6T_RT_FST)) { 116 return ret; 117 } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) { 118 pr_debug("Not strict "); 119 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) { 120 pr_debug("There isn't enough space\n"); 121 return false; 122 } else { 123 unsigned int i = 0; 124 125 pr_debug("#%d ", rtinfo->addrnr); 126 for (temp = 0; 127 temp < (unsigned int)((hdrlen - 8) / 16); 128 temp++) { 129 ap = skb_header_pointer(skb, 130 ptr 131 + sizeof(struct rt0_hdr) 132 + temp * sizeof(_addr), 133 sizeof(_addr), 134 &_addr); 135 136 if (ap == NULL) { 137 par->hotdrop = true; 138 return false; 139 } 140 141 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) { 142 pr_debug("i=%d temp=%d;\n", i, temp); 143 i++; 144 } 145 if (i == rtinfo->addrnr) 146 break; 147 } 148 pr_debug("i=%d #%d\n", i, rtinfo->addrnr); 149 if (i == rtinfo->addrnr) 150 return ret; 151 else 152 return false; 153 } 154 } else { 155 pr_debug("Strict "); 156 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) { 157 pr_debug("There isn't enough space\n"); 158 return false; 159 } else { 160 pr_debug("#%d ", rtinfo->addrnr); 161 for (temp = 0; temp < rtinfo->addrnr; temp++) { 162 ap = skb_header_pointer(skb, 163 ptr 164 + sizeof(struct rt0_hdr) 165 + temp * sizeof(_addr), 166 sizeof(_addr), 167 &_addr); 168 if (ap == NULL) { 169 par->hotdrop = true; 170 return false; 171 } 172 173 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp])) 174 break; 175 } 176 pr_debug("temp=%d #%d\n", temp, rtinfo->addrnr); 177 if (temp == rtinfo->addrnr && 178 temp == (unsigned int)((hdrlen - 8) / 16)) 179 return ret; 180 else 181 return false; 182 } 183 } 184 185 return false; 186 } 187 188 static int rt_mt6_check(const struct xt_mtchk_param *par) 189 { 190 const struct ip6t_rt *rtinfo = par->matchinfo; 191 192 if (rtinfo->invflags & ~IP6T_RT_INV_MASK) { 193 pr_debug("unknown flags %X\n", rtinfo->invflags); 194 return -EINVAL; 195 } 196 if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) && 197 (!(rtinfo->flags & IP6T_RT_TYP) || 198 (rtinfo->rt_type != 0) || 199 (rtinfo->invflags & IP6T_RT_INV_TYP))) { 200 pr_debug("`--rt-type 0' required before `--rt-0-*'"); 201 return -EINVAL; 202 } 203 204 return 0; 205 } 206 207 static struct xt_match rt_mt6_reg __read_mostly = { 208 .name = "rt", 209 .family = NFPROTO_IPV6, 210 .match = rt_mt6, 211 .matchsize = sizeof(struct ip6t_rt), 212 .checkentry = rt_mt6_check, 213 .me = THIS_MODULE, 214 }; 215 216 static int __init rt_mt6_init(void) 217 { 218 return xt_register_match(&rt_mt6_reg); 219 } 220 221 static void __exit rt_mt6_exit(void) 222 { 223 xt_unregister_match(&rt_mt6_reg); 224 } 225 226 module_init(rt_mt6_init); 227 module_exit(rt_mt6_exit); 228