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   1 From: Pablo Neira Ayuso <pablo@netfilter.org>
   2 Date: Mon, 27 Nov 2017 22:29:52 +0100
   3 Subject: [PATCH] netfilter: move route indirection to struct nf_ipv6_ops
   4
   5 We cannot make a direct call to nf_ip6_route() because that would result
   6 in autoloading the 'ipv6' module because of symbol dependencies.
   7 Therefore, define route indirection in nf_ipv6_ops where this really
   8 belongs to.
   9
  10 For IPv4, we can indeed make a direct function call, which is faster,
  11 given IPv4 is built-in in the networking code by default. Still,
  12 CONFIG_INET=n and CONFIG_NETFILTER=y is possible, so define empty inline
  13 stub for IPv4 in such case.
  14
  15 Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
  16 ---
  17
  18 --- a/include/linux/netfilter.h
  19 +++ b/include/linux/netfilter.h
  20 @@ -274,8 +274,6 @@ struct nf_queue_entry;
  21
  22  struct nf_afinfo {
  23         unsigned short  family;
  24 -       int             (*route)(struct net *net, struct dst_entry **dst,
  25 -                                struct flowi *fl, bool strict);
  26         int             (*reroute)(struct net *net, struct sk_buff *skb,
  27                                    const struct nf_queue_entry *entry);
  28         int             route_key_size;
  29 @@ -294,6 +292,8 @@ __sum16 nf_checksum(struct sk_buff *skb,
  30  __sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
  31                             unsigned int dataoff, unsigned int len,
  32                             u_int8_t protocol, unsigned short family);
  33 +int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
  34 +            bool strict, unsigned short family);
  35
  36  int nf_register_afinfo(const struct nf_afinfo *afinfo);
  37  void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
  38 --- a/include/linux/netfilter_ipv4.h
  39 +++ b/include/linux/netfilter_ipv4.h
  40 @@ -24,6 +24,8 @@ __sum16 nf_ip_checksum(struct sk_buff *s
  41  __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
  42                                unsigned int dataoff, unsigned int len,
  43                                u_int8_t protocol);
  44 +int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
  45 +               bool strict);
  46  #else
  47  static inline __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
  48                                      unsigned int dataoff, u_int8_t protocol)
  49 @@ -38,6 +40,11 @@ static inline __sum16 nf_ip_checksum_par
  50  {
  51         return 0;
  52  }
  53 +static inline int nf_ip_route(struct net *net, struct dst_entry **dst,
  54 +                             struct flowi *fl, bool strict)
  55 +{
  56 +       return -EOPNOTSUPP;
  57 +}
  58  #endif /* CONFIG_INET */
  59
  60  #endif /*__LINUX_IP_NETFILTER_H*/
  61 --- a/include/linux/netfilter_ipv6.h
  62 +++ b/include/linux/netfilter_ipv6.h
  63 @@ -33,6 +33,8 @@ struct nf_ipv6_ops {
  64         __sum16 (*checksum_partial)(struct sk_buff *skb, unsigned int hook,
  65                                     unsigned int dataoff, unsigned int len,
  66                                     u_int8_t protocol);
  67 +       int (*route)(struct net *net, struct dst_entry **dst, struct flowi *fl,
  68 +                    bool strict);
  69  };
  70
  71  #ifdef CONFIG_NETFILTER
  72 --- a/net/bridge/netfilter/nf_tables_bridge.c
  73 +++ b/net/bridge/netfilter/nf_tables_bridge.c
  74 @@ -101,15 +101,8 @@ static int nf_br_reroute(struct net *net
  75         return 0;
  76  }
  77
  78 -static int nf_br_route(struct net *net, struct dst_entry **dst,
  79 -                      struct flowi *fl, bool strict __always_unused)
  80 -{
  81 -       return 0;
  82 -}
  83 -
  84  static const struct nf_afinfo nf_br_afinfo = {
  85         .family                 = AF_BRIDGE,
  86 -       .route                  = nf_br_route,
  87         .reroute                = nf_br_reroute,
  88         .route_key_size         = 0,
  89  };
  90 --- a/net/ipv4/netfilter.c
  91 +++ b/net/ipv4/netfilter.c
  92 @@ -150,8 +150,8 @@ __sum16 nf_ip_checksum_partial(struct sk
  93  }
  94  EXPORT_SYMBOL_GPL(nf_ip_checksum_partial);
  95
  96 -static int nf_ip_route(struct net *net, struct dst_entry **dst,
  97 -                      struct flowi *fl, bool strict __always_unused)
  98 +int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
  99 +               bool strict __always_unused)
 100  {
 101         struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
 102         if (IS_ERR(rt))
 103 @@ -159,10 +159,10 @@ static int nf_ip_route(struct net *net,
 104         *dst = &rt->dst;
 105         return 0;
 106  }
 107 +EXPORT_SYMBOL_GPL(nf_ip_route);
 108
 109  static const struct nf_afinfo nf_ip_afinfo = {
 110         .family                 = AF_INET,
 111 -       .route                  = nf_ip_route,
 112         .reroute                = nf_ip_reroute,
 113         .route_key_size         = sizeof(struct ip_rt_info),
 114  };
 115 --- a/net/ipv6/netfilter.c
 116 +++ b/net/ipv6/netfilter.c
 117 @@ -171,11 +171,11 @@ static const struct nf_ipv6_ops ipv6ops
 118         .fragment               = ip6_fragment,
 119         .checksum               = nf_ip6_checksum,
 120         .checksum_partial       = nf_ip6_checksum_partial,
 121 +       .route                  = nf_ip6_route,
 122  };
 123
 124  static const struct nf_afinfo nf_ip6_afinfo = {
 125         .family                 = AF_INET6,
 126 -       .route                  = nf_ip6_route,
 127         .reroute                = nf_ip6_reroute,
 128         .route_key_size         = sizeof(struct ip6_rt_info),
 129  };
 130 --- a/net/ipv6/netfilter/nft_fib_ipv6.c
 131 +++ b/net/ipv6/netfilter/nft_fib_ipv6.c
 132 @@ -60,7 +60,6 @@ static u32 __nft_fib6_eval_type(const st
 133  {
 134         const struct net_device *dev = NULL;
 135         const struct nf_ipv6_ops *v6ops;
 136 -       const struct nf_afinfo *afinfo;
 137         int route_err, addrtype;
 138         struct rt6_info *rt;
 139         struct flowi6 fl6 = {
 140 @@ -69,8 +68,8 @@ static u32 __nft_fib6_eval_type(const st
 141         };
 142         u32 ret = 0;
 143
 144 -       afinfo = nf_get_afinfo(NFPROTO_IPV6);
 145 -       if (!afinfo)
 146 +       v6ops = nf_get_ipv6_ops();
 147 +       if (!v6ops)
 148                 return RTN_UNREACHABLE;
 149
 150         if (priv->flags & NFTA_FIB_F_IIF)
 151 @@ -80,12 +79,11 @@ static u32 __nft_fib6_eval_type(const st
 152
 153         nft_fib6_flowi_init(&fl6, priv, pkt, dev, iph);
 154
 155 -       v6ops = nf_get_ipv6_ops();
 156 -       if (dev && v6ops && v6ops->chk_addr(nft_net(pkt), &fl6.daddr, dev, true))
 157 +       if (dev && v6ops->chk_addr(nft_net(pkt), &fl6.daddr, dev, true))
 158                 ret = RTN_LOCAL;
 159
 160 -       route_err = afinfo->route(nft_net(pkt), (struct dst_entry **)&rt,
 161 -                                 flowi6_to_flowi(&fl6), false);
 162 +       route_err = v6ops->route(nft_net(pkt), (struct dst_entry **)&rt,
 163 +                                flowi6_to_flowi(&fl6), false);
 164         if (route_err)
 165                 goto err;
 166
 167 --- a/net/netfilter/nf_conntrack_h323_main.c
 168 +++ b/net/netfilter/nf_conntrack_h323_main.c
 169 @@ -24,6 +24,7 @@
 170  #include <linux/skbuff.h>
 171  #include <net/route.h>
 172  #include <net/ip6_route.h>
 173 +#include <linux/netfilter_ipv6.h>
 174
 175  #include <net/netfilter/nf_conntrack.h>
 176  #include <net/netfilter/nf_conntrack_core.h>
 177 @@ -732,14 +733,8 @@ static int callforward_do_filter(struct
 178                                  const union nf_inet_addr *dst,
 179                                  u_int8_t family)
 180  {
 181 -       const struct nf_afinfo *afinfo;
 182         int ret = 0;
 183
 184 -       /* rcu_read_lock()ed by nf_hook_thresh */
 185 -       afinfo = nf_get_afinfo(family);
 186 -       if (!afinfo)
 187 -               return 0;
 188 -
 189         switch (family) {
 190         case AF_INET: {
 191                 struct flowi4 fl1, fl2;
 192 @@ -750,10 +745,10 @@ static int callforward_do_filter(struct
 193
 194                 memset(&fl2, 0, sizeof(fl2));
 195                 fl2.daddr = dst->ip;
 196 -               if (!afinfo->route(net, (struct dst_entry **)&rt1,
 197 -                                  flowi4_to_flowi(&fl1), false)) {
 198 -                       if (!afinfo->route(net, (struct dst_entry **)&rt2,
 199 -                                          flowi4_to_flowi(&fl2), false)) {
 200 +               if (!nf_ip_route(net, (struct dst_entry **)&rt1,
 201 +                                flowi4_to_flowi(&fl1), false)) {
 202 +                       if (!nf_ip_route(net, (struct dst_entry **)&rt2,
 203 +                                        flowi4_to_flowi(&fl2), false)) {
 204                                 if (rt_nexthop(rt1, fl1.daddr) ==
 205                                     rt_nexthop(rt2, fl2.daddr) &&
 206                                     rt1->dst.dev  == rt2->dst.dev)
 207 @@ -766,18 +761,23 @@ static int callforward_do_filter(struct
 208         }
 209  #if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV6)
 210         case AF_INET6: {
 211 -               struct flowi6 fl1, fl2;
 212 +               const struct nf_ipv6_ops *v6ops;
 213                 struct rt6_info *rt1, *rt2;
 214 +               struct flowi6 fl1, fl2;
 215 +
 216 +               v6ops = nf_get_ipv6_ops();
 217 +               if (!v6ops)
 218 +                       return 0;
 219
 220                 memset(&fl1, 0, sizeof(fl1));
 221                 fl1.daddr = src->in6;
 222
 223                 memset(&fl2, 0, sizeof(fl2));
 224                 fl2.daddr = dst->in6;
 225 -               if (!afinfo->route(net, (struct dst_entry **)&rt1,
 226 -                                  flowi6_to_flowi(&fl1), false)) {
 227 -                       if (!afinfo->route(net, (struct dst_entry **)&rt2,
 228 -                                          flowi6_to_flowi(&fl2), false)) {
 229 +               if (!v6ops->route(net, (struct dst_entry **)&rt1,
 230 +                                 flowi6_to_flowi(&fl1), false)) {
 231 +                       if (!v6ops->route(net, (struct dst_entry **)&rt2,
 232 +                                         flowi6_to_flowi(&fl2), false)) {
 233                                 if (ipv6_addr_equal(rt6_nexthop(rt1, &fl1.daddr),
 234                                                     rt6_nexthop(rt2, &fl2.daddr)) &&
 235                                     rt1->dst.dev == rt2->dst.dev)
 236 --- a/net/netfilter/nft_rt.c
 237 +++ b/net/netfilter/nft_rt.c
 238 @@ -27,7 +27,7 @@ static u16 get_tcpmss(const struct nft_p
 239  {
 240         u32 minlen = sizeof(struct ipv6hdr), mtu = dst_mtu(skbdst);
 241         const struct sk_buff *skb = pkt->skb;
 242 -       const struct nf_afinfo *ai;
 243 +       struct dst_entry *dst = NULL;
 244         struct flowi fl;
 245
 246         memset(&fl, 0, sizeof(fl));
 247 @@ -43,15 +43,10 @@ static u16 get_tcpmss(const struct nft_p
 248                 break;
 249         }
 250
 251 -       ai = nf_get_afinfo(nft_pf(pkt));
 252 -       if (ai) {
 253 -               struct dst_entry *dst = NULL;
 254 -
 255 -               ai->route(nft_net(pkt), &dst, &fl, false);
 256 -               if (dst) {
 257 -                       mtu = min(mtu, dst_mtu(dst));
 258 -                       dst_release(dst);
 259 -               }
 260 +       nf_route(nft_net(pkt), &dst, &fl, false, nft_pf(pkt));
 261 +       if (dst) {
 262 +               mtu = min(mtu, dst_mtu(dst));
 263 +               dst_release(dst);
 264         }
 265
 266         if (mtu <= minlen || mtu > 0xffff)
 267 --- a/net/netfilter/utils.c
 268 +++ b/net/netfilter/utils.c
 269 @@ -48,3 +48,24 @@ __sum16 nf_checksum_partial(struct sk_bu
 270         return csum;
 271  }
 272  EXPORT_SYMBOL_GPL(nf_checksum_partial);
 273 +
 274 +int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
 275 +            bool strict, unsigned short family)
 276 +{
 277 +       const struct nf_ipv6_ops *v6ops;
 278 +       int ret = 0;
 279 +
 280 +       switch (family) {
 281 +       case AF_INET:
 282 +               ret = nf_ip_route(net, dst, fl, strict);
 283 +               break;
 284 +       case AF_INET6:
 285 +               v6ops = rcu_dereference(nf_ipv6_ops);
 286 +               if (v6ops)
 287 +                       ret = v6ops->route(net, dst, fl, strict);
 288 +               break;
 289 +       }
 290 +
 291 +       return ret;
 292 +}
 293 +EXPORT_SYMBOL_GPL(nf_route);
 294 --- a/net/netfilter/xt_TCPMSS.c
 295 +++ b/net/netfilter/xt_TCPMSS.c
 296 @@ -48,7 +48,6 @@ static u_int32_t tcpmss_reverse_mtu(stru
 297                                     unsigned int family)
 298  {
 299         struct flowi fl;
 300 -       const struct nf_afinfo *ai;
 301         struct rtable *rt = NULL;
 302         u_int32_t mtu     = ~0U;
 303
 304 @@ -62,10 +61,8 @@ static u_int32_t tcpmss_reverse_mtu(stru
 305                 memset(fl6, 0, sizeof(*fl6));
 306                 fl6->daddr = ipv6_hdr(skb)->saddr;
 307         }
 308 -       ai = nf_get_afinfo(family);
 309 -       if (ai != NULL)
 310 -               ai->route(net, (struct dst_entry **)&rt, &fl, false);
 311
 312 +       nf_route(net, (struct dst_entry **)&rt, &fl, false, family);
 313         if (rt != NULL) {
 314                 mtu = dst_mtu(&rt->dst);
 315                 dst_release(&rt->dst);
 316 --- a/net/netfilter/xt_addrtype.c
 317 +++ b/net/netfilter/xt_addrtype.c
 318 @@ -36,7 +36,7 @@ MODULE_ALIAS("ip6t_addrtype");
 319  static u32 match_lookup_rt6(struct net *net, const struct net_device *dev,
 320                             const struct in6_addr *addr, u16 mask)
 321  {
 322 -       const struct nf_afinfo *afinfo;
 323 +       const struct nf_ipv6_ops *v6ops;
 324         struct flowi6 flow;
 325         struct rt6_info *rt;
 326         u32 ret = 0;
 327 @@ -47,17 +47,14 @@ static u32 match_lookup_rt6(struct net *
 328         if (dev)
 329                 flow.flowi6_oif = dev->ifindex;
 330
 331 -       afinfo = nf_get_afinfo(NFPROTO_IPV6);
 332 -       if (afinfo != NULL) {
 333 -               const struct nf_ipv6_ops *v6ops;
 334 -
 335 +       v6ops = nf_get_ipv6_ops();
 336 +       if (v6ops) {
 337                 if (dev && (mask & XT_ADDRTYPE_LOCAL)) {
 338 -                       v6ops = nf_get_ipv6_ops();
 339 -                       if (v6ops && v6ops->chk_addr(net, addr, dev, true))
 340 +                       if (v6ops->chk_addr(net, addr, dev, true))
 341                                 ret = XT_ADDRTYPE_LOCAL;
 342                 }
 343 -               route_err = afinfo->route(net, (struct dst_entry **)&rt,
 344 -                                         flowi6_to_flowi(&flow), false);
 345 +               route_err = v6ops->route(net, (struct dst_entry **)&rt,
 346 +                                        flowi6_to_flowi(&flow), false);
 347         } else {
 348                 route_err = 1;
 349         }