[PATCH nft 2/3] src: improve error reporting when setting policy on non-base chain

[Pablo Neira Ayuso <pablo@netfilter.org>]

When trying to set a policy to non-base chain:

 # nft add chain x y { policy accept\; }
 Error: Could not process rule: Operation not supported
 add chain x y { policy accept; }
                 ^^^^^^^^^^^^^

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/mnl.c          | 12 +++++++-----
 src/parser_bison.y |  3 ++-
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/mnl.c b/src/mnl.c
index f959196922fc..6d1e476444ef 100644
--- a/src/mnl.c
+++ b/src/mnl.c
@@ -619,11 +619,6 @@ int mnl_nft_chain_add(struct netlink_ctx *ctx, struct cmd *cmd,
 			nftnl_chain_set_str(nlc, NFTNL_CHAIN_TYPE,
 					    cmd->chain->type);
 		}
-		if (cmd->chain->policy) {
-			mpz_export_data(&policy, cmd->chain->policy->value,
-					BYTEORDER_HOST_ENDIAN, sizeof(int));
-			nftnl_chain_set_u32(nlc, NFTNL_CHAIN_POLICY, policy);
-		}
 		if (cmd->chain->dev_expr) {
 			dev_array = xmalloc(sizeof(char *) * 8);
 			dev_array_len = 8;
@@ -658,6 +653,13 @@ int mnl_nft_chain_add(struct netlink_ctx *ctx, struct cmd *cmd,
 	cmd_add_loc(cmd, nlh->nlmsg_len, &cmd->handle.chain.location);
 	mnl_attr_put_strz(nlh, NFTA_CHAIN_NAME, cmd->handle.chain.name);
 
+	if (cmd && cmd->chain->policy) {
+		mpz_export_data(&policy, cmd->chain->policy->value,
+				BYTEORDER_HOST_ENDIAN, sizeof(int));
+		cmd_add_loc(cmd, nlh->nlmsg_len, &cmd->chain->policy->location);
+		mnl_attr_put_u32(nlh, NFTA_CHAIN_POLICY, htonl(policy));
+	}
+
 	nftnl_chain_nlmsg_build_payload(nlh, nlc);
 	nftnl_chain_free(nlc);
 
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 819c78bfa6d1..cc77d0420cb0 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -2160,7 +2160,8 @@ policy_spec		:	POLICY		policy_expr
 					expr_free($2);
 					YYERROR;
 				}
-				$<chain>0->policy	= $2;
+				$<chain>0->policy		= $2;
+				$<chain>0->policy->location	= @$;
 			}
 			;
 
-- 
2.11.0