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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 | // SPDX-License-Identifier: GPL-2.0-only /* Kernel module to match Hop-by-Hop and Destination parameters. */ /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/skbuff.h> #include <linux/ipv6.h> #include <linux/types.h> #include <net/checksum.h> #include <net/ipv6.h> #include <asm/byteorder.h> #include <linux/netfilter/x_tables.h> #include <linux/netfilter_ipv6/ip6_tables.h> #include <linux/netfilter_ipv6/ip6t_opts.h> MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("Xtables: IPv6 Hop-By-Hop and Destination Header match"); MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); MODULE_ALIAS("ip6t_dst"); /* * (Type & 0xC0) >> 6 * 0 -> ignorable * 1 -> must drop the packet * 2 -> send ICMP PARM PROB regardless and drop packet * 3 -> Send ICMP if not a multicast address and drop packet * (Type & 0x20) >> 5 * 0 -> invariant * 1 -> can change the routing * (Type & 0x1F) Type * 0 -> Pad1 (only 1 byte!) * 1 -> PadN LENGTH info (total length = length + 2) * C0 | 2 -> JUMBO 4 x x x x ( xxxx > 64k ) * 5 -> RTALERT 2 x x */ static struct xt_match hbh_mt6_reg[] __read_mostly; static bool hbh_mt6(const struct sk_buff *skb, struct xt_action_param *par) { struct ipv6_opt_hdr _optsh; const struct ipv6_opt_hdr *oh; const struct ip6t_opts *optinfo = par->matchinfo; unsigned int temp; unsigned int ptr = 0; unsigned int hdrlen = 0; bool ret = false; u8 _opttype; u8 _optlen; const u_int8_t *tp = NULL; const u_int8_t *lp = NULL; unsigned int optlen; int err; err = ipv6_find_hdr(skb, &ptr, (par->match == &hbh_mt6_reg[0]) ? NEXTHDR_HOP : NEXTHDR_DEST, NULL, NULL); if (err < 0) { if (err != -ENOENT) par->hotdrop = true; return false; } oh = skb_header_pointer(skb, ptr, sizeof(_optsh), &_optsh); if (oh == NULL) { par->hotdrop = true; return false; } hdrlen = ipv6_optlen(oh); if (skb->len - ptr < hdrlen) { /* Packet smaller than it's length field */ return false; } pr_debug("IPv6 OPTS LEN %u %u ", hdrlen, oh->hdrlen); pr_debug("len %02X %04X %02X ", optinfo->hdrlen, hdrlen, (!(optinfo->flags & IP6T_OPTS_LEN) || ((optinfo->hdrlen == hdrlen) ^ !!(optinfo->invflags & IP6T_OPTS_INV_LEN)))); ret = (!(optinfo->flags & IP6T_OPTS_LEN) || ((optinfo->hdrlen == hdrlen) ^ !!(optinfo->invflags & IP6T_OPTS_INV_LEN))); ptr += 2; hdrlen -= 2; if (!(optinfo->flags & IP6T_OPTS_OPTS)) { return ret; } else { pr_debug("Strict "); pr_debug("#%d ", optinfo->optsnr); for (temp = 0; temp < optinfo->optsnr; temp++) { /* type field exists ? */ if (hdrlen < 1) break; tp = skb_header_pointer(skb, ptr, sizeof(_opttype), &_opttype); if (tp == NULL) break; /* Type check */ if (*tp != (optinfo->opts[temp] & 0xFF00) >> 8) { pr_debug("Tbad %02X %02X\n", *tp, (optinfo->opts[temp] & 0xFF00) >> 8); return false; } else { pr_debug("Tok "); } /* Length check */ if (*tp) { u16 spec_len; /* length field exists ? */ if (hdrlen < 2) break; lp = skb_header_pointer(skb, ptr + 1, sizeof(_optlen), &_optlen); if (lp == NULL) break; spec_len = optinfo->opts[temp] & 0x00FF; if (spec_len != 0x00FF && spec_len != *lp) { pr_debug("Lbad %02X %04X\n", *lp, spec_len); return false; } pr_debug("Lok "); optlen = *lp + 2; } else { pr_debug("Pad1\n"); optlen = 1; } /* Step to the next */ pr_debug("len%04X\n", optlen); if ((ptr > skb->len - optlen || hdrlen < optlen) && temp < optinfo->optsnr - 1) { pr_debug("new pointer is too large!\n"); break; } ptr += optlen; hdrlen -= optlen; } if (temp == optinfo->optsnr) return ret; else return false; } return false; } static int hbh_mt6_check(const struct xt_mtchk_param *par) { const struct ip6t_opts *optsinfo = par->matchinfo; if (optsinfo->invflags & ~IP6T_OPTS_INV_MASK) { pr_debug("unknown flags %X\n", optsinfo->invflags); return -EINVAL; } if (optsinfo->flags & IP6T_OPTS_NSTRICT) { pr_debug("Not strict - not implemented"); return -EINVAL; } return 0; } static struct xt_match hbh_mt6_reg[] __read_mostly = { { /* Note, hbh_mt6 relies on the order of hbh_mt6_reg */ .name = "hbh", .family = NFPROTO_IPV6, .match = hbh_mt6, .matchsize = sizeof(struct ip6t_opts), .checkentry = hbh_mt6_check, .me = THIS_MODULE, }, { .name = "dst", .family = NFPROTO_IPV6, .match = hbh_mt6, .matchsize = sizeof(struct ip6t_opts), .checkentry = hbh_mt6_check, .me = THIS_MODULE, }, }; static int __init hbh_mt6_init(void) { return xt_register_matches(hbh_mt6_reg, ARRAY_SIZE(hbh_mt6_reg)); } static void __exit hbh_mt6_exit(void) { xt_unregister_matches(hbh_mt6_reg, ARRAY_SIZE(hbh_mt6_reg)); } module_init(hbh_mt6_init); module_exit(hbh_mt6_exit); |