diff mbox series

[net-next,05/11] netfilter: nf_tables: avoid false-positive lockdep splat on rule deletion

Message ID 20241106234625.168468-6-pablo@netfilter.org (mailing list archive)
State Accepted
Commit 9adbb4198bf6cf3634032871118a7052aeaa573f
Delegated to: Netdev Maintainers
Headers show
Series [net-next,01/11] netfilter: Make legacy configs user selectable | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 3 this patch: 3
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers fail 2 blamed authors not CCed: joel@joelfernandes.org paulmck@kernel.org; 5 maintainers not CCed: horms@kernel.org kadlec@netfilter.org coreteam@netfilter.org joel@joelfernandes.org paulmck@kernel.org
netdev/build_clang success Errors and warnings before: 3 this patch: 3
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 14 this patch: 14
netdev/checkpatch warning WARNING: line length of 88 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 5 this patch: 5
netdev/source_inline success Was 0 now: 0
netdev/contest fail net-next-2024-11-07--03-00 (tests: 786)

Commit Message

Pablo Neira Ayuso Nov. 6, 2024, 11:46 p.m. UTC 
From: Florian Westphal <fw@strlen.de>

On rule delete we get:
 WARNING: suspicious RCU usage
 net/netfilter/nf_tables_api.c:3420 RCU-list traversed in non-reader section!!
 1 lock held by iptables/134:
   #0: ffff888008c4fcc8 (&nft_net->commit_mutex){+.+.}-{3:3}, at: nf_tables_valid_genid (include/linux/jiffies.h:101) nf_tables

Code is fine, no other CPU can change the list because we're holding
transaction mutex.

Pass the needed lockdep annotation to the iterator and fix
two comments for functions that are no longer restricted to rcu-only
context.

This is enough to resolve rule delete, but there are several other
missing annotations, added in followup-patches.

Fixes: 28875945ba98 ("rcu: Add support for consolidated-RCU reader checking")
Reported-by: Matthieu Baerts <matttbe@kernel.org>
Tested-by: Matthieu Baerts <matttbe@kernel.org>
Closes: https://lore.kernel.org/netfilter-devel/da27f17f-3145-47af-ad0f-7fd2a823623e@kernel.org/
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 30331688301e..80c285ac7e07 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3411,13 +3411,15 @@  void nft_expr_destroy(const struct nft_ctx *ctx, struct nft_expr *expr)
  * Rules
  */
 
-static struct nft_rule *__nft_rule_lookup(const struct nft_chain *chain,
+static struct nft_rule *__nft_rule_lookup(const struct net *net,
+					  const struct nft_chain *chain,
 					  u64 handle)
 {
 	struct nft_rule *rule;
 
 	// FIXME: this sucks
-	list_for_each_entry_rcu(rule, &chain->rules, list) {
+	list_for_each_entry_rcu(rule, &chain->rules, list,
+				lockdep_commit_lock_is_held(net)) {
 		if (handle == rule->handle)
 			return rule;
 	}
@@ -3425,13 +3427,14 @@  static struct nft_rule *__nft_rule_lookup(const struct nft_chain *chain,
 	return ERR_PTR(-ENOENT);
 }
 
-static struct nft_rule *nft_rule_lookup(const struct nft_chain *chain,
+static struct nft_rule *nft_rule_lookup(const struct net *net,
+					const struct nft_chain *chain,
 					const struct nlattr *nla)
 {
 	if (nla == NULL)
 		return ERR_PTR(-EINVAL);
 
-	return __nft_rule_lookup(chain, be64_to_cpu(nla_get_be64(nla)));
+	return __nft_rule_lookup(net, chain, be64_to_cpu(nla_get_be64(nla)));
 }
 
 static const struct nla_policy nft_rule_policy[NFTA_RULE_MAX + 1] = {
@@ -3732,7 +3735,7 @@  static int nf_tables_dump_rules_done(struct netlink_callback *cb)
 	return 0;
 }
 
-/* called with rcu_read_lock held */
+/* Caller must hold rcu read lock or transaction mutex */
 static struct sk_buff *
 nf_tables_getrule_single(u32 portid, const struct nfnl_info *info,
 			 const struct nlattr * const nla[], bool reset)
@@ -3759,7 +3762,7 @@  nf_tables_getrule_single(u32 portid, const struct nfnl_info *info,
 		return ERR_CAST(chain);
 	}
 
-	rule = nft_rule_lookup(chain, nla[NFTA_RULE_HANDLE]);
+	rule = nft_rule_lookup(net, chain, nla[NFTA_RULE_HANDLE]);
 	if (IS_ERR(rule)) {
 		NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
 		return ERR_CAST(rule);
@@ -4057,7 +4060,7 @@  static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
 
 	if (nla[NFTA_RULE_HANDLE]) {
 		handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_HANDLE]));
-		rule = __nft_rule_lookup(chain, handle);
+		rule = __nft_rule_lookup(net, chain, handle);
 		if (IS_ERR(rule)) {
 			NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
 			return PTR_ERR(rule);
@@ -4079,7 +4082,7 @@  static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
 
 		if (nla[NFTA_RULE_POSITION]) {
 			pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION]));
-			old_rule = __nft_rule_lookup(chain, pos_handle);
+			old_rule = __nft_rule_lookup(net, chain, pos_handle);
 			if (IS_ERR(old_rule)) {
 				NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION]);
 				return PTR_ERR(old_rule);
@@ -4296,7 +4299,7 @@  static int nf_tables_delrule(struct sk_buff *skb, const struct nfnl_info *info,
 
 	if (chain) {
 		if (nla[NFTA_RULE_HANDLE]) {
-			rule = nft_rule_lookup(chain, nla[NFTA_RULE_HANDLE]);
+			rule = nft_rule_lookup(info->net, chain, nla[NFTA_RULE_HANDLE]);
 			if (IS_ERR(rule)) {
 				if (PTR_ERR(rule) == -ENOENT &&
 				    NFNL_MSG_TYPE(info->nlh->nlmsg_type) == NFT_MSG_DESTROYRULE)
@@ -8101,7 +8104,7 @@  static int nf_tables_dump_obj_done(struct netlink_callback *cb)
 	return 0;
 }
 
-/* called with rcu_read_lock held */
+/* Caller must hold rcu read lock or transaction mutex */
 static struct sk_buff *
 nf_tables_getobj_single(u32 portid, const struct nfnl_info *info,
 			const struct nlattr * const nla[], bool reset)