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   1 From: Pablo Neira Ayuso <pablo@netfilter.org>
   2 Date: Mon, 27 Nov 2017 21:55:14 +0100
   3 Subject: [PATCH] netfilter: move checksum indirection to struct nf_ipv6_ops
   4
   5 We cannot make a direct call to nf_ip6_checksum() because that would
   6 result in autoloading the 'ipv6' module because of symbol dependencies.
   7 Therefore, define checksum 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  create mode 100644 net/netfilter/utils.c
  18
  19 --- a/include/linux/netfilter.h
  20 +++ b/include/linux/netfilter.h
  21 @@ -311,8 +311,6 @@ struct nf_queue_entry;
  22
  23  struct nf_afinfo {
  24         unsigned short  family;
  25 -       __sum16         (*checksum)(struct sk_buff *skb, unsigned int hook,
  26 -                                   unsigned int dataoff, u_int8_t protocol);
  27         __sum16         (*checksum_partial)(struct sk_buff *skb,
  28                                             unsigned int hook,
  29                                             unsigned int dataoff,
  30 @@ -333,20 +331,9 @@ static inline const struct nf_afinfo *nf
  31         return rcu_dereference(nf_afinfo[family]);
  32  }
  33
  34 -static inline __sum16
  35 -nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
  36 -           u_int8_t protocol, unsigned short family)
  37 -{
  38 -       const struct nf_afinfo *afinfo;
  39 -       __sum16 csum = 0;
  40 -
  41 -       rcu_read_lock();
  42 -       afinfo = nf_get_afinfo(family);
  43 -       if (afinfo)
  44 -               csum = afinfo->checksum(skb, hook, dataoff, protocol);
  45 -       rcu_read_unlock();
  46 -       return csum;
  47 -}
  48 +__sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
  49 +                   unsigned int dataoff, u_int8_t protocol,
  50 +                   unsigned short family);
  51
  52  static inline __sum16
  53  nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
  54 --- a/include/linux/netfilter_ipv4.h
  55 +++ b/include/linux/netfilter_ipv4.h
  56 @@ -7,6 +7,16 @@
  57  #include <uapi/linux/netfilter_ipv4.h>
  58
  59  int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned addr_type);
  60 +
  61 +#ifdef CONFIG_INET
  62  __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
  63                        unsigned int dataoff, u_int8_t protocol);
  64 +#else
  65 +static inline __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
  66 +                                    unsigned int dataoff, u_int8_t protocol)
  67 +{
  68 +       return 0;
  69 +}
  70 +#endif /* CONFIG_INET */
  71 +
  72  #endif /*__LINUX_IP_NETFILTER_H*/
  73 --- a/include/linux/netfilter_ipv6.h
  74 +++ b/include/linux/netfilter_ipv6.h
  75 @@ -19,6 +19,8 @@ struct nf_ipv6_ops {
  76         void (*route_input)(struct sk_buff *skb);
  77         int (*fragment)(struct net *net, struct sock *sk, struct sk_buff *skb,
  78                         int (*output)(struct net *, struct sock *, struct sk_buff *));
  79 +       __sum16 (*checksum)(struct sk_buff *skb, unsigned int hook,
  80 +                           unsigned int dataoff, u_int8_t protocol);
  81  };
  82
  83  #ifdef CONFIG_NETFILTER
  84 --- a/net/bridge/netfilter/nf_tables_bridge.c
  85 +++ b/net/bridge/netfilter/nf_tables_bridge.c
  86 @@ -106,12 +106,6 @@ static int nf_br_reroute(struct net *net
  87         return 0;
  88  }
  89
  90 -static __sum16 nf_br_checksum(struct sk_buff *skb, unsigned int hook,
  91 -                             unsigned int dataoff, u_int8_t protocol)
  92 -{
  93 -       return 0;
  94 -}
  95 -
  96  static __sum16 nf_br_checksum_partial(struct sk_buff *skb, unsigned int hook,
  97                                       unsigned int dataoff, unsigned int len,
  98                                       u_int8_t protocol)
  99 @@ -127,7 +121,6 @@ static int nf_br_route(struct net *net,
 100
 101  static const struct nf_afinfo nf_br_afinfo = {
 102         .family                 = AF_BRIDGE,
 103 -       .checksum               = nf_br_checksum,
 104         .checksum_partial       = nf_br_checksum_partial,
 105         .route                  = nf_br_route,
 106         .saveroute              = nf_br_saveroute,
 107 --- a/net/ipv4/netfilter.c
 108 +++ b/net/ipv4/netfilter.c
 109 @@ -188,7 +188,6 @@ static int nf_ip_route(struct net *net,
 110
 111  static const struct nf_afinfo nf_ip_afinfo = {
 112         .family                 = AF_INET,
 113 -       .checksum               = nf_ip_checksum,
 114         .checksum_partial       = nf_ip_checksum_partial,
 115         .route                  = nf_ip_route,
 116         .saveroute              = nf_ip_saveroute,
 117 --- a/net/ipv6/netfilter.c
 118 +++ b/net/ipv6/netfilter.c
 119 @@ -194,12 +194,12 @@ static __sum16 nf_ip6_checksum_partial(s
 120  static const struct nf_ipv6_ops ipv6ops = {
 121         .chk_addr       = ipv6_chk_addr,
 122         .route_input    = ip6_route_input,
 123 -       .fragment       = ip6_fragment
 124 +       .fragment       = ip6_fragment,
 125 +       .checksum       = nf_ip6_checksum,
 126  };
 127
 128  static const struct nf_afinfo nf_ip6_afinfo = {
 129         .family                 = AF_INET6,
 130 -       .checksum               = nf_ip6_checksum,
 131         .checksum_partial       = nf_ip6_checksum_partial,
 132         .route                  = nf_ip6_route,
 133         .saveroute              = nf_ip6_saveroute,
 134 --- a/net/netfilter/Makefile
 135 +++ b/net/netfilter/Makefile
 136 @@ -1,5 +1,5 @@
 137  # SPDX-License-Identifier: GPL-2.0
 138 -netfilter-objs := core.o nf_log.o nf_queue.o nf_sockopt.o
 139 +netfilter-objs := core.o nf_log.o nf_queue.o nf_sockopt.o utils.o
 140
 141  nf_conntrack-y := nf_conntrack_core.o nf_conntrack_standalone.o nf_conntrack_expect.o nf_conntrack_helper.o nf_conntrack_proto.o nf_conntrack_l3proto_generic.o nf_conntrack_proto_generic.o nf_conntrack_proto_tcp.o nf_conntrack_proto_udp.o nf_conntrack_extend.o nf_conntrack_acct.o nf_conntrack_seqadj.o
 142  nf_conntrack-$(CONFIG_NF_CONNTRACK_TIMEOUT) += nf_conntrack_timeout.o
 143 --- /dev/null
 144 +++ b/net/netfilter/utils.c
 145 @@ -0,0 +1,26 @@
 146 +#include <linux/kernel.h>
 147 +#include <linux/netfilter.h>
 148 +#include <linux/netfilter_ipv4.h>
 149 +#include <linux/netfilter_ipv6.h>
 150 +
 151 +__sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
 152 +                   unsigned int dataoff, u_int8_t protocol,
 153 +                   unsigned short family)
 154 +{
 155 +       const struct nf_ipv6_ops *v6ops;
 156 +       __sum16 csum = 0;
 157 +
 158 +       switch (family) {
 159 +       case AF_INET:
 160 +               csum = nf_ip_checksum(skb, hook, dataoff, protocol);
 161 +               break;
 162 +       case AF_INET6:
 163 +               v6ops = rcu_dereference(nf_ipv6_ops);
 164 +               if (v6ops)
 165 +                       csum = v6ops->checksum(skb, hook, dataoff, protocol);
 166 +               break;
 167 +       }
 168 +
 169 +       return csum;
 170 +}
 171 +EXPORT_SYMBOL_GPL(nf_checksum);