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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 | // SPDX-License-Identifier: GPL-2.0-or-later /* Kernel module to match Segment Routing Header (SRH) parameters. */ /* Author: * Ahmed Abdelsalam <amsalam20@gmail.com> */ #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/ipv6.h> #include <net/seg6.h> #include <linux/netfilter/x_tables.h> #include <linux/netfilter_ipv6/ip6t_srh.h> #include <linux/netfilter_ipv6/ip6_tables.h> /* Test a struct->mt_invflags and a boolean for inequality */ #define NF_SRH_INVF(ptr, flag, boolean) \ ((boolean) ^ !!((ptr)->mt_invflags & (flag))) static bool srh_mt6(const struct sk_buff *skb, struct xt_action_param *par) { const struct ip6t_srh *srhinfo = par->matchinfo; struct ipv6_sr_hdr *srh; struct ipv6_sr_hdr _srh; int hdrlen, srhoff = 0; if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, NULL) < 0) return false; srh = skb_header_pointer(skb, srhoff, sizeof(_srh), &_srh); if (!srh) return false; hdrlen = ipv6_optlen(srh); if (skb->len - srhoff < hdrlen) return false; if (srh->type != IPV6_SRCRT_TYPE_4) return false; if (srh->segments_left > srh->first_segment) return false; /* Next Header matching */ if (srhinfo->mt_flags & IP6T_SRH_NEXTHDR) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_NEXTHDR, !(srh->nexthdr == srhinfo->next_hdr))) return false; /* Header Extension Length matching */ if (srhinfo->mt_flags & IP6T_SRH_LEN_EQ) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_EQ, !(srh->hdrlen == srhinfo->hdr_len))) return false; if (srhinfo->mt_flags & IP6T_SRH_LEN_GT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_GT, !(srh->hdrlen > srhinfo->hdr_len))) return false; if (srhinfo->mt_flags & IP6T_SRH_LEN_LT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_LT, !(srh->hdrlen < srhinfo->hdr_len))) return false; /* Segments Left matching */ if (srhinfo->mt_flags & IP6T_SRH_SEGS_EQ) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_EQ, !(srh->segments_left == srhinfo->segs_left))) return false; if (srhinfo->mt_flags & IP6T_SRH_SEGS_GT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_GT, !(srh->segments_left > srhinfo->segs_left))) return false; if (srhinfo->mt_flags & IP6T_SRH_SEGS_LT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_LT, !(srh->segments_left < srhinfo->segs_left))) return false; /** * Last Entry matching * Last_Entry field was introduced in revision 6 of the SRH draft. * It was called First_Segment in the previous revision */ if (srhinfo->mt_flags & IP6T_SRH_LAST_EQ) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_EQ, !(srh->first_segment == srhinfo->last_entry))) return false; if (srhinfo->mt_flags & IP6T_SRH_LAST_GT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_GT, !(srh->first_segment > srhinfo->last_entry))) return false; if (srhinfo->mt_flags & IP6T_SRH_LAST_LT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_LT, !(srh->first_segment < srhinfo->last_entry))) return false; /** * Tag matchig * Tag field was introduced in revision 6 of the SRH draft. */ if (srhinfo->mt_flags & IP6T_SRH_TAG) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_TAG, !(srh->tag == srhinfo->tag))) return false; return true; } static bool srh1_mt6(const struct sk_buff *skb, struct xt_action_param *par) { int hdrlen, psidoff, nsidoff, lsidoff, srhoff = 0; const struct ip6t_srh1 *srhinfo = par->matchinfo; struct in6_addr *psid, *nsid, *lsid; struct in6_addr _psid, _nsid, _lsid; struct ipv6_sr_hdr *srh; struct ipv6_sr_hdr _srh; if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, NULL) < 0) return false; srh = skb_header_pointer(skb, srhoff, sizeof(_srh), &_srh); if (!srh) return false; hdrlen = ipv6_optlen(srh); if (skb->len - srhoff < hdrlen) return false; if (srh->type != IPV6_SRCRT_TYPE_4) return false; if (srh->segments_left > srh->first_segment) return false; /* Next Header matching */ if (srhinfo->mt_flags & IP6T_SRH_NEXTHDR) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_NEXTHDR, !(srh->nexthdr == srhinfo->next_hdr))) return false; /* Header Extension Length matching */ if (srhinfo->mt_flags & IP6T_SRH_LEN_EQ) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_EQ, !(srh->hdrlen == srhinfo->hdr_len))) return false; if (srhinfo->mt_flags & IP6T_SRH_LEN_GT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_GT, !(srh->hdrlen > srhinfo->hdr_len))) return false; if (srhinfo->mt_flags & IP6T_SRH_LEN_LT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_LT, !(srh->hdrlen < srhinfo->hdr_len))) return false; /* Segments Left matching */ if (srhinfo->mt_flags & IP6T_SRH_SEGS_EQ) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_EQ, !(srh->segments_left == srhinfo->segs_left))) return false; if (srhinfo->mt_flags & IP6T_SRH_SEGS_GT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_GT, !(srh->segments_left > srhinfo->segs_left))) return false; if (srhinfo->mt_flags & IP6T_SRH_SEGS_LT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_LT, !(srh->segments_left < srhinfo->segs_left))) return false; /** * Last Entry matching * Last_Entry field was introduced in revision 6 of the SRH draft. * It was called First_Segment in the previous revision */ if (srhinfo->mt_flags & IP6T_SRH_LAST_EQ) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_EQ, !(srh->first_segment == srhinfo->last_entry))) return false; if (srhinfo->mt_flags & IP6T_SRH_LAST_GT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_GT, !(srh->first_segment > srhinfo->last_entry))) return false; if (srhinfo->mt_flags & IP6T_SRH_LAST_LT) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_LT, !(srh->first_segment < srhinfo->last_entry))) return false; /** * Tag matchig * Tag field was introduced in revision 6 of the SRH draft */ if (srhinfo->mt_flags & IP6T_SRH_TAG) if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_TAG, !(srh->tag == srhinfo->tag))) return false; /* Previous SID matching */ if (srhinfo->mt_flags & IP6T_SRH_PSID) { if (srh->segments_left == srh->first_segment) return false; psidoff = srhoff + sizeof(struct ipv6_sr_hdr) + ((srh->segments_left + 1) * sizeof(struct in6_addr)); psid = skb_header_pointer(skb, psidoff, sizeof(_psid), &_psid); if (!psid) return false; if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_PSID, ipv6_masked_addr_cmp(psid, &srhinfo->psid_msk, &srhinfo->psid_addr))) return false; } /* Next SID matching */ if (srhinfo->mt_flags & IP6T_SRH_NSID) { if (srh->segments_left == 0) return false; nsidoff = srhoff + sizeof(struct ipv6_sr_hdr) + ((srh->segments_left - 1) * sizeof(struct in6_addr)); nsid = skb_header_pointer(skb, nsidoff, sizeof(_nsid), &_nsid); if (!nsid) return false; if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_NSID, ipv6_masked_addr_cmp(nsid, &srhinfo->nsid_msk, &srhinfo->nsid_addr))) return false; } /* Last SID matching */ if (srhinfo->mt_flags & IP6T_SRH_LSID) { lsidoff = srhoff + sizeof(struct ipv6_sr_hdr); lsid = skb_header_pointer(skb, lsidoff, sizeof(_lsid), &_lsid); if (!lsid) return false; if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LSID, ipv6_masked_addr_cmp(lsid, &srhinfo->lsid_msk, &srhinfo->lsid_addr))) return false; } return true; } static int srh_mt6_check(const struct xt_mtchk_param *par) { const struct ip6t_srh *srhinfo = par->matchinfo; if (srhinfo->mt_flags & ~IP6T_SRH_MASK) { pr_info_ratelimited("unknown srh match flags %X\n", srhinfo->mt_flags); return -EINVAL; } if (srhinfo->mt_invflags & ~IP6T_SRH_INV_MASK) { pr_info_ratelimited("unknown srh invflags %X\n", srhinfo->mt_invflags); return -EINVAL; } return 0; } static int srh1_mt6_check(const struct xt_mtchk_param *par) { const struct ip6t_srh1 *srhinfo = par->matchinfo; if (srhinfo->mt_flags & ~IP6T_SRH_MASK) { pr_info_ratelimited("unknown srh match flags %X\n", srhinfo->mt_flags); return -EINVAL; } if (srhinfo->mt_invflags & ~IP6T_SRH_INV_MASK) { pr_info_ratelimited("unknown srh invflags %X\n", srhinfo->mt_invflags); return -EINVAL; } return 0; } static struct xt_match srh_mt6_reg[] __read_mostly = { { .name = "srh", .revision = 0, .family = NFPROTO_IPV6, .match = srh_mt6, .matchsize = sizeof(struct ip6t_srh), .checkentry = srh_mt6_check, .me = THIS_MODULE, }, { .name = "srh", .revision = 1, .family = NFPROTO_IPV6, .match = srh1_mt6, .matchsize = sizeof(struct ip6t_srh1), .checkentry = srh1_mt6_check, .me = THIS_MODULE, } }; static int __init srh_mt6_init(void) { return xt_register_matches(srh_mt6_reg, ARRAY_SIZE(srh_mt6_reg)); } static void __exit srh_mt6_exit(void) { xt_unregister_matches(srh_mt6_reg, ARRAY_SIZE(srh_mt6_reg)); } module_init(srh_mt6_init); module_exit(srh_mt6_exit); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("Xtables: IPv6 Segment Routing Header match"); MODULE_AUTHOR("Ahmed Abdelsalam <amsalam20@gmail.com>"); |