mnl: revisit hook listing

Update this command to display the hook datapath for a packet depending
on its family.

This patch also includes:

- Group of existing hooks based on the hook location.
- Order hooks by priority, from INT_MIN to INT_MAX.
- Do not add sign to priority zero.
- Refresh include/linux/netfilter/nfnetlink_hook.h cache copy.
- Use NFNLA_CHAIN_* attributes to print the chain family, table and name.
  If NFNLA_CHAIN_* attributes are not available, display the hookfn name.
- Update syntax: remove optional hook parameter, promote the 'device'
  argument.

The following example shows the hook datapath for IPv4 packets coming in
from netdevice 'eth0':

 # nft list hooks ip device eth0
 family ip {
        hook ingress {
                +0000000010 chain netdev x y [nf_tables]
                +0000000300 chain inet m w  [nf_tables]
        }
        hook input {
                -0000000100 chain ip a b [nf_tables]
                +0000000300 chain inet m z [nf_tables]
        }
        hook forward {
                -0000000225 selinux_ipv4_forward
                 0000000000 chain ip a c [nf_tables]
        }
        hook output {
                -0000000225 selinux_ipv4_output
        }
        hook postrouting {
                +0000000225 selinux_ipv4_postroute
        }
 }

Note that the listing above includes the existing netdev and inet
hooks/chains which *might* interfer in the travel of an incoming IPv4
packet. This allows users to debug the pipeline, basically, to
understand in what order the hooks/chains are evaluated for the IPv4
packets.

If the netdevice is not specified, then the ingress hooks are not
shown.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/rule.h b/include/rule.h
index 357326a3..be316956 100644
--- a/include/rule.h
+++ b/include/rule.h
@@ -270,6 +270,7 @@ extern struct chain *chain_binding_lookup(const struct table *table,
 					  const char *chain_name);
 
 extern const char *family2str(unsigned int family);
+#define __NF_ARP_INGRESS	255
 extern const char *hooknum2str(unsigned int family, unsigned int hooknum);
 extern const char *chain_policy2str(uint32_t policy);
 extern void chain_print_plain(const struct chain *chain,