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, 5 insertions, 20 deletions

diff --git a/src/parser_bison.y b/src/parser_bison.y
index b83ac9a2..83f0250a 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -1474,11 +1474,7 @@ list_cmd		:	TABLE		table_spec
 			}
 			;
 
-basehook_device_name	:	/* NULL */
-			{
-				$$ = NULL;
-			}
-			|	DEVICE STRING
+basehook_device_name	:	DEVICE STRING
 			{
 				$$ = $2;
 			}
@@ -1488,22 +1484,11 @@ basehook_spec		:	ruleset_spec
 			{
 				$$ = $1;
 			}
-			|	ruleset_spec    STRING  basehook_device_name
+			|	ruleset_spec    basehook_device_name
 			{
-				const char *name = chain_hookname_lookup($2);
-
-				if (name == NULL) {
-					erec_queue(error(&@2, "unknown chain hook"),
-						   state->msgs);
-					xfree($3);
-					YYERROR;
-				}
-
-				$1.chain.name = $2;
-				$1.chain.location = @2;
-				if ($3) {
-					$1.obj.name = $3;
-					$1.obj.location = @3;
+				if ($2) {
+					$1.obj.name = $2;
+					$1.obj.location = @2;
 				}
 				$$ = $1;
 			}