net/netfilter/xt_HMARK.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * xt_HMARK - Netfilter module to set mark by means of hashing
   4  *
   5  * (C) 2012 by Hans Schillstrom <hans.schillstrom@ericsson.com>
   6  * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/icmp.h>
  14
  15 #include <linux/netfilter/x_tables.h>
  16 #include <linux/netfilter/xt_HMARK.h>
  17
  18 #include <net/ip.h>
  19 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  20 #include <net/netfilter/nf_conntrack.h>
  21 #endif
  22 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
  23 #include <net/ipv6.h>
  24 #include <linux/netfilter_ipv6/ip6_tables.h>
  25 #endif
  26
  27 MODULE_LICENSE("GPL");
  28 MODULE_AUTHOR("Hans Schillstrom <hans.schillstrom@ericsson.com>");
  29 MODULE_DESCRIPTION("Xtables: packet marking using hash calculation");
  30 MODULE_ALIAS("ipt_HMARK");
  31 MODULE_ALIAS("ip6t_HMARK");
  32
  33 struct hmark_tuple {
  34         __be32                  src;
  35         __be32                  dst;
  36         union hmark_ports       uports;
  37         u8                      proto;
  38 };
  39
  40 static inline __be32 hmark_addr6_mask(const __be32 *addr32, const __be32 *mask)
  41 {
  42         return (addr32[0] & mask[0]) ^
  43                (addr32[1] & mask[1]) ^
  44                (addr32[2] & mask[2]) ^
  45                (addr32[3] & mask[3]);
  46 }
  47
  48 static inline __be32
  49 hmark_addr_mask(int l3num, const __be32 *addr32, const __be32 *mask)
  50 {
  51         switch (l3num) {
  52         case AF_INET:
  53                 return *addr32 & *mask;
  54         case AF_INET6:
  55                 return hmark_addr6_mask(addr32, mask);
  56         }
  57         return 0;
  58 }
  59
  60 static inline void hmark_swap_ports(union hmark_ports *uports,
  61                                     const struct xt_hmark_info *info)
  62 {
  63         union hmark_ports hp;
  64         u16 src, dst;
  65
  66         hp.b32 = (uports->b32 & info->port_mask.b32) | info->port_set.b32;
  67         src = ntohs(hp.b16.src);
  68         dst = ntohs(hp.b16.dst);
  69
  70         if (dst > src)
  71                 uports->v32 = (dst << 16) | src;
  72         else
  73                 uports->v32 = (src << 16) | dst;
  74 }
  75
  76 static int
  77 hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t,
  78                     const struct xt_hmark_info *info)
  79 {
  80 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  81         enum ip_conntrack_info ctinfo;
  82         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  83         struct nf_conntrack_tuple *otuple;
  84         struct nf_conntrack_tuple *rtuple;
  85
  86         if (ct == NULL)
  87                 return -1;
  88
  89         otuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
  90         rtuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
  91
  92         t->src = hmark_addr_mask(otuple->src.l3num, otuple->src.u3.ip6,
  93                                  info->src_mask.ip6);
  94         t->dst = hmark_addr_mask(otuple->src.l3num, rtuple->src.u3.ip6,
  95                                  info->dst_mask.ip6);
  96
  97         if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
  98                 return 0;
  99
 100         t->proto = nf_ct_protonum(ct);
 101         if (t->proto != IPPROTO_ICMP) {
 102                 t->uports.b16.src = otuple->src.u.all;
 103                 t->uports.b16.dst = rtuple->src.u.all;
 104                 hmark_swap_ports(&t->uports, info);
 105         }
 106
 107         return 0;
 108 #else
 109         return -1;
 110 #endif
 111 }
 112
 113 /* This hash function is endian independent, to ensure consistent hashing if
 114  * the cluster is composed of big and little endian systems. */
 115 static inline u32
 116 hmark_hash(struct hmark_tuple *t, const struct xt_hmark_info *info)
 117 {
 118         u32 hash;
 119         u32 src = ntohl(t->src);
 120         u32 dst = ntohl(t->dst);
 121
 122         if (dst < src)
 123                 swap(src, dst);
 124
 125         hash = jhash_3words(src, dst, t->uports.v32, info->hashrnd);
 126         hash = hash ^ (t->proto & info->proto_mask);
 127
 128         return reciprocal_scale(hash, info->hmodulus) + info->hoffset;
 129 }
 130
 131 static void
 132 hmark_set_tuple_ports(const struct sk_buff *skb, unsigned int nhoff,
 133                       struct hmark_tuple *t, const struct xt_hmark_info *info)
 134 {
 135         int protoff;
 136
 137         protoff = proto_ports_offset(t->proto);
 138         if (protoff < 0)
 139                 return;
 140
 141         nhoff += protoff;
 142         if (skb_copy_bits(skb, nhoff, &t->uports, sizeof(t->uports)) < 0)
 143                 return;
 144
 145         hmark_swap_ports(&t->uports, info);
 146 }
 147
 148 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 149 static int get_inner6_hdr(const struct sk_buff *skb, int *offset)
 150 {
 151         struct icmp6hdr *icmp6h, _ih6;
 152
 153         icmp6h = skb_header_pointer(skb, *offset, sizeof(_ih6), &_ih6);
 154         if (icmp6h == NULL)
 155                 return 0;
 156
 157         if (icmp6h->icmp6_type && icmp6h->icmp6_type < 128) {
 158                 *offset += sizeof(struct icmp6hdr);
 159                 return 1;
 160         }
 161         return 0;
 162 }
 163
 164 static int
 165 hmark_pkt_set_htuple_ipv6(const struct sk_buff *skb, struct hmark_tuple *t,
 166                           const struct xt_hmark_info *info)
 167 {
 168         struct ipv6hdr *ip6, _ip6;
 169         int flag = IP6_FH_F_AUTH;
 170         unsigned int nhoff = 0;
 171         u16 fragoff = 0;
 172         int nexthdr;
 173
 174         ip6 = (struct ipv6hdr *) (skb->data + skb_network_offset(skb));
 175         nexthdr = ipv6_find_hdr(skb, &nhoff, -1, &fragoff, &flag);
 176         if (nexthdr < 0)
 177                 return 0;
 178         /* No need to check for icmp errors on fragments */
 179         if ((flag & IP6_FH_F_FRAG) || (nexthdr != IPPROTO_ICMPV6))
 180                 goto noicmp;
 181         /* Use inner header in case of ICMP errors */
 182         if (get_inner6_hdr(skb, &nhoff)) {
 183                 ip6 = skb_header_pointer(skb, nhoff, sizeof(_ip6), &_ip6);
 184                 if (ip6 == NULL)
 185                         return -1;
 186                 /* If AH present, use SPI like in ESP. */
 187                 flag = IP6_FH_F_AUTH;
 188                 nexthdr = ipv6_find_hdr(skb, &nhoff, -1, &fragoff, &flag);
 189                 if (nexthdr < 0)
 190                         return -1;
 191         }
 192 noicmp:
 193         t->src = hmark_addr6_mask(ip6->saddr.s6_addr32, info->src_mask.ip6);
 194         t->dst = hmark_addr6_mask(ip6->daddr.s6_addr32, info->dst_mask.ip6);
 195
 196         if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
 197                 return 0;
 198
 199         t->proto = nexthdr;
 200         if (t->proto == IPPROTO_ICMPV6)
 201                 return 0;
 202
 203         if (flag & IP6_FH_F_FRAG)
 204                 return 0;
 205
 206         hmark_set_tuple_ports(skb, nhoff, t, info);
 207         return 0;
 208 }
 209
 210 static unsigned int
 211 hmark_tg_v6(struct sk_buff *skb, const struct xt_action_param *par)
 212 {
 213         const struct xt_hmark_info *info = par->targinfo;
 214         struct hmark_tuple t;
 215
 216         memset(&t, 0, sizeof(struct hmark_tuple));
 217
 218         if (info->flags & XT_HMARK_FLAG(XT_HMARK_CT)) {
 219                 if (hmark_ct_set_htuple(skb, &t, info) < 0)
 220                         return XT_CONTINUE;
 221         } else {
 222                 if (hmark_pkt_set_htuple_ipv6(skb, &t, info) < 0)
 223                         return XT_CONTINUE;
 224         }
 225
 226         skb->mark = hmark_hash(&t, info);
 227         return XT_CONTINUE;
 228 }
 229 #endif
 230
 231 static int get_inner_hdr(const struct sk_buff *skb, int iphsz, int *nhoff)
 232 {
 233         const struct icmphdr *icmph;
 234         struct icmphdr _ih;
 235
 236         /* Not enough header? */
 237         icmph = skb_header_pointer(skb, *nhoff + iphsz, sizeof(_ih), &_ih);
 238         if (icmph == NULL || icmph->type > NR_ICMP_TYPES)
 239                 return 0;
 240
 241         /* Error message? */
 242         if (!icmp_is_err(icmph->type))
 243                 return 0;
 244
 245         *nhoff += iphsz + sizeof(_ih);
 246         return 1;
 247 }
 248
 249 static int
 250 hmark_pkt_set_htuple_ipv4(const struct sk_buff *skb, struct hmark_tuple *t,
 251                           const struct xt_hmark_info *info)
 252 {
 253         struct iphdr *ip, _ip;
 254         int nhoff = skb_network_offset(skb);
 255
 256         ip = (struct iphdr *) (skb->data + nhoff);
 257         if (ip->protocol == IPPROTO_ICMP) {
 258                 /* Use inner header in case of ICMP errors */
 259                 if (get_inner_hdr(skb, ip->ihl * 4, &nhoff)) {
 260                         ip = skb_header_pointer(skb, nhoff, sizeof(_ip), &_ip);
 261                         if (ip == NULL)
 262                                 return -1;
 263                 }
 264         }
 265
 266         t->src = ip->saddr & info->src_mask.ip;
 267         t->dst = ip->daddr & info->dst_mask.ip;
 268
 269         if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
 270                 return 0;
 271
 272         t->proto = ip->protocol;
 273
 274         /* ICMP has no ports, skip */
 275         if (t->proto == IPPROTO_ICMP)
 276                 return 0;
 277
 278         /* follow-up fragments don't contain ports, skip all fragments */
 279         if (ip_is_fragment(ip))
 280                 return 0;
 281
 282         hmark_set_tuple_ports(skb, (ip->ihl * 4) + nhoff, t, info);
 283
 284         return 0;
 285 }
 286
 287 static unsigned int
 288 hmark_tg_v4(struct sk_buff *skb, const struct xt_action_param *par)
 289 {
 290         const struct xt_hmark_info *info = par->targinfo;
 291         struct hmark_tuple t;
 292
 293         memset(&t, 0, sizeof(struct hmark_tuple));
 294
 295         if (info->flags & XT_HMARK_FLAG(XT_HMARK_CT)) {
 296                 if (hmark_ct_set_htuple(skb, &t, info) < 0)
 297                         return XT_CONTINUE;
 298         } else {
 299                 if (hmark_pkt_set_htuple_ipv4(skb, &t, info) < 0)
 300                         return XT_CONTINUE;
 301         }
 302
 303         skb->mark = hmark_hash(&t, info);
 304         return XT_CONTINUE;
 305 }
 306
 307 static int hmark_tg_check(const struct xt_tgchk_param *par)
 308 {
 309         const struct xt_hmark_info *info = par->targinfo;
 310         const char *errmsg = "proto mask must be zero with L3 mode";
 311
 312         if (!info->hmodulus)
 313                 return -EINVAL;
 314
 315         if (info->proto_mask &&
 316             (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3)))
 317                 goto err;
 318
 319         if (info->flags & XT_HMARK_FLAG(XT_HMARK_SPI_MASK) &&
 320             (info->flags & (XT_HMARK_FLAG(XT_HMARK_SPORT_MASK) |
 321                              XT_HMARK_FLAG(XT_HMARK_DPORT_MASK))))
 322                 return -EINVAL;
 323
 324         if (info->flags & XT_HMARK_FLAG(XT_HMARK_SPI) &&
 325             (info->flags & (XT_HMARK_FLAG(XT_HMARK_SPORT) |
 326                              XT_HMARK_FLAG(XT_HMARK_DPORT)))) {
 327                 errmsg = "spi-set and port-set can't be combined";
 328                 goto err;
 329         }
 330         return 0;
 331 err:
 332         pr_info_ratelimited("%s\n", errmsg);
 333         return -EINVAL;
 334 }
 335
 336 static struct xt_target hmark_tg_reg[] __read_mostly = {
 337         {
 338                 .name           = "HMARK",
 339                 .family         = NFPROTO_IPV4,
 340                 .target         = hmark_tg_v4,
 341                 .targetsize     = sizeof(struct xt_hmark_info),
 342                 .checkentry     = hmark_tg_check,
 343                 .me             = THIS_MODULE,
 344         },
 345 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 346         {
 347                 .name           = "HMARK",
 348                 .family         = NFPROTO_IPV6,
 349                 .target         = hmark_tg_v6,
 350                 .targetsize     = sizeof(struct xt_hmark_info),
 351                 .checkentry     = hmark_tg_check,
 352                 .me             = THIS_MODULE,
 353         },
 354 #endif
 355 };
 356
 357 static int __init hmark_tg_init(void)
 358 {
 359         return xt_register_targets(hmark_tg_reg, ARRAY_SIZE(hmark_tg_reg));
 360 }
 361
 362 static void __exit hmark_tg_exit(void)
 363 {
 364         xt_unregister_targets(hmark_tg_reg, ARRAY_SIZE(hmark_tg_reg));
 365 }
 366
 367 module_init(hmark_tg_init);
 368 module_exit(hmark_tg_exit);