netdev - [PATCH 3/4] netfilter: nftables: extend error reporting for chain updates

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Date:   Wed, 14 Oct 2020 01:45:58 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH 3/4] netfilter: nftables: extend error reporting for chain updates

The initial support for netlink extended ACK is missing the chain update
path, which results in misleading error reporting in case of EEXIST.

Fixes 36dd1bcc07e5 ("netfilter: nf_tables: initial support for extended ACK reporting")
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_tables_api.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 4603b667973a..0e43063767d6 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2103,7 +2103,8 @@ static bool nft_hook_list_equal(struct list_head *hook_list1,
 }
 
 static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
-			      u32 flags)
+			      u32 flags, const struct nlattr *attr,
+			      struct netlink_ext_ack *extack)
 {
 	const struct nlattr * const *nla = ctx->nla;
 	struct nft_table *table = ctx->table;
@@ -2119,9 +2120,10 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
 		return -EOPNOTSUPP;
 
 	if (nla[NFTA_CHAIN_HOOK]) {
-		if (!nft_is_base_chain(chain))
+		if (!nft_is_base_chain(chain)) {
+			NL_SET_BAD_ATTR(extack, attr);
 			return -EEXIST;
-
+		}
 		err = nft_chain_parse_hook(ctx->net, nla, &hook, ctx->family,
 					   false);
 		if (err < 0)
@@ -2130,6 +2132,7 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
 		basechain = nft_base_chain(chain);
 		if (basechain->type != hook.type) {
 			nft_chain_release_hook(&hook);
+			NL_SET_BAD_ATTR(extack, attr);
 			return -EEXIST;
 		}
 
@@ -2137,6 +2140,7 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
 			if (!nft_hook_list_equal(&basechain->hook_list,
 						 &hook.list)) {
 				nft_chain_release_hook(&hook);
+				NL_SET_BAD_ATTR(extack, attr);
 				return -EEXIST;
 			}
 		} else {
@@ -2144,6 +2148,7 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
 			if (ops->hooknum != hook.num ||
 			    ops->priority != hook.priority) {
 				nft_chain_release_hook(&hook);
+				NL_SET_BAD_ATTR(extack, attr);
 				return -EEXIST;
 			}
 		}
@@ -2156,8 +2161,10 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
 
 		chain2 = nft_chain_lookup(ctx->net, table,
 					  nla[NFTA_CHAIN_NAME], genmask);
-		if (!IS_ERR(chain2))
+		if (!IS_ERR(chain2)) {
+			NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_NAME]);
 			return -EEXIST;
+		}
 	}
 
 	if (nla[NFTA_CHAIN_COUNTERS]) {
@@ -2200,6 +2207,7 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
 			    nft_trans_chain_update(tmp) &&
 			    nft_trans_chain_name(tmp) &&
 			    strcmp(name, nft_trans_chain_name(tmp)) == 0) {
+				NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_NAME]);
 				kfree(name);
 				goto err;
 			}
@@ -2322,7 +2330,8 @@ static int nf_tables_newchain(struct net *net, struct sock *nlsk,
 			return -EOPNOTSUPP;
 
 		flags |= chain->flags & NFT_CHAIN_BASE;
-		return nf_tables_updchain(&ctx, genmask, policy, flags);
+		return nf_tables_updchain(&ctx, genmask, policy, flags, attr,
+					  extack);
 	}
 
 	return nf_tables_addchain(&ctx, family, genmask, policy, flags);
-- 
2.20.1