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, 12 insertions, 2 deletions

diff --git a/include/linux/netfilter/nfnetlink_hook.h b/include/linux/netfilter/nfnetlink_hook.h
index d8ac8278..bbcd285b 100644
--- a/include/linux/netfilter/nfnetlink_hook.h
+++ b/include/linux/netfilter/nfnetlink_hook.h
@@ -8,10 +8,10 @@ enum nfnl_hook_msg_types {
 };
 
 /**
- * enum nfnl_hook_attributes - nf_tables netfilter hook netlink attributes
+ * enum nfnl_hook_attributes - netfilter hook netlink attributes
  *
  * @NFNLA_HOOK_HOOKNUM: netfilter hook number (NLA_U32)
- * @NFNLAA_HOOK_PRIORITY: netfilter hook priority (NLA_U32)
+ * @NFNLA_HOOK_PRIORITY: netfilter hook priority (NLA_U32)
  * @NFNLA_HOOK_DEV: netdevice name (NLA_STRING)
  * @NFNLA_HOOK_FUNCTION_NAME: hook function name (NLA_STRING)
  * @NFNLA_HOOK_MODULE_NAME: kernel module that registered this hook (NLA_STRING)
@@ -43,6 +43,15 @@ enum nfnl_hook_chain_info_attributes {
 };
 #define NFNLA_HOOK_INFO_MAX (__NFNLA_HOOK_INFO_MAX - 1)
 
+enum nfnl_hook_chain_desc_attributes {
+	NFNLA_CHAIN_UNSPEC,
+	NFNLA_CHAIN_TABLE,
+	NFNLA_CHAIN_FAMILY,
+	NFNLA_CHAIN_NAME,
+	__NFNLA_CHAIN_MAX,
+};
+#define NFNLA_CHAIN_MAX (__NFNLA_CHAIN_MAX - 1)
+
 /**
  * enum nfnl_hook_chaintype - chain type
  *
@@ -51,4 +60,5 @@ enum nfnl_hook_chain_info_attributes {
 enum nfnl_hook_chaintype {
 	NFNL_HOOK_TYPE_NFTABLES = 0x1,
 };
+
 #endif /* _NFNL_HOOK_H */