diff mbox series

[net-next,5/8] netfilter: nf_tables: Don't allocate nft_rule_dump_ctx

Message ID 20231010145343.12551-6-fw@strlen.de (mailing list archive)
State Accepted
Commit 99ab9f84b85ec3eec099278bff61269ad0b078ce
Delegated to: Netdev Maintainers
Headers show
Series [net-next,1/8] netfilter: nf_tables: Always allocate nft_rule_dump_ctx | 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/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: 1377 this patch: 1377
netdev/cc_maintainers warning 3 maintainers not CCed: kadlec@netfilter.org coreteam@netfilter.org pablo@netfilter.org
netdev/build_clang success Errors and warnings before: 1386 this patch: 1386
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 No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1402 this patch: 1402
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 62 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Florian Westphal Oct. 10, 2023, 2:53 p.m. UTC 
From: Phil Sutter <phil@nwl.cc>

Since struct netlink_callback::args is not used by rule dumpers anymore,
use it to hold nft_rule_dump_ctx. Add a build-time check to make sure it
won't ever exceed the available space.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nf_tables_api.c | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index a2e6c826bd08..68321345bb6d 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3453,7 +3453,7 @@  static int __nf_tables_dump_rules(struct sk_buff *skb,
 				  const struct nft_table *table,
 				  const struct nft_chain *chain)
 {
-	struct nft_rule_dump_ctx *ctx = cb->data;
+	struct nft_rule_dump_ctx *ctx = (void *)cb->ctx;
 	struct net *net = sock_net(skb->sk);
 	const struct nft_rule *rule, *prule;
 	unsigned int entries = 0;
@@ -3498,7 +3498,7 @@  static int nf_tables_dump_rules(struct sk_buff *skb,
 				struct netlink_callback *cb)
 {
 	const struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh);
-	struct nft_rule_dump_ctx *ctx = cb->data;
+	struct nft_rule_dump_ctx *ctx = (void *)cb->ctx;
 	struct nft_table *table;
 	const struct nft_chain *chain;
 	unsigned int idx = 0;
@@ -3553,42 +3553,35 @@  static int nf_tables_dump_rules(struct sk_buff *skb,
 
 static int nf_tables_dump_rules_start(struct netlink_callback *cb)
 {
+	struct nft_rule_dump_ctx *ctx = (void *)cb->ctx;
 	const struct nlattr * const *nla = cb->data;
-	struct nft_rule_dump_ctx *ctx = NULL;
 
-	ctx = kzalloc(sizeof(*ctx), GFP_ATOMIC);
-	if (!ctx)
-		return -ENOMEM;
+	BUILD_BUG_ON(sizeof(*ctx) > sizeof(cb->ctx));
 
 	if (nla[NFTA_RULE_TABLE]) {
 		ctx->table = nla_strdup(nla[NFTA_RULE_TABLE], GFP_ATOMIC);
-		if (!ctx->table) {
-			kfree(ctx);
+		if (!ctx->table)
 			return -ENOMEM;
-		}
 	}
 	if (nla[NFTA_RULE_CHAIN]) {
 		ctx->chain = nla_strdup(nla[NFTA_RULE_CHAIN], GFP_ATOMIC);
 		if (!ctx->chain) {
 			kfree(ctx->table);
-			kfree(ctx);
 			return -ENOMEM;
 		}
 	}
 	if (NFNL_MSG_TYPE(cb->nlh->nlmsg_type) == NFT_MSG_GETRULE_RESET)
 		ctx->reset = true;
 
-	cb->data = ctx;
 	return 0;
 }
 
 static int nf_tables_dump_rules_done(struct netlink_callback *cb)
 {
-	struct nft_rule_dump_ctx *ctx = cb->data;
+	struct nft_rule_dump_ctx *ctx = (void *)cb->ctx;
 
 	kfree(ctx->table);
 	kfree(ctx->chain);
-	kfree(ctx);
 	return 0;
 }