diff mbox series

[net,3/8] netfilter: nf_tables: do not allow CHAIN_ID to refer to another table

Message ID 20220809220532.130240-4-pablo@netfilter.org (mailing list archive)
State Accepted
Commit 95f466d22364a33d183509629d0879885b4f547e
Delegated to: Netdev Maintainers
Headers show
Series [net,1/8] netfilter: nf_tables: validate variable length element extension | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Pull request is its own cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 16 this patch: 16
netdev/cc_maintainers warning 3 maintainers not CCed: coreteam@netfilter.org kadlec@netfilter.org fw@strlen.de
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
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: 16 this patch: 16
netdev/checkpatch warning WARNING: line length of 83 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Pablo Neira Ayuso Aug. 9, 2022, 10:05 p.m. UTC 
From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

When doing lookups for chains on the same batch by using its ID, a chain
from a different table can be used. If a rule is added to a table but
refers to a chain in a different table, it will be linked to the chain in
table2, but would have expressions referring to objects in table1.

Then, when table1 is removed, the rule will not be removed as its linked to
a chain in table2. When expressions in the rule are processed or removed,
that will lead to a use-after-free.

When looking for chains by ID, use the table that was used for the lookup
by name, and only return chains belonging to that same table.

Fixes: 837830a4b439 ("netfilter: nf_tables: add NFTA_RULE_CHAIN_ID attribute")
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 41c529b0001c..041accbaca32 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2472,6 +2472,7 @@  static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
 }
 
 static struct nft_chain *nft_chain_lookup_byid(const struct net *net,
+					       const struct nft_table *table,
 					       const struct nlattr *nla)
 {
 	struct nftables_pernet *nft_net = nft_pernet(net);
@@ -2482,6 +2483,7 @@  static struct nft_chain *nft_chain_lookup_byid(const struct net *net,
 		struct nft_chain *chain = trans->ctx.chain;
 
 		if (trans->msg_type == NFT_MSG_NEWCHAIN &&
+		    chain->table == table &&
 		    id == nft_trans_chain_id(trans))
 			return chain;
 	}
@@ -3417,7 +3419,7 @@  static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
 			return -EOPNOTSUPP;
 
 	} else if (nla[NFTA_RULE_CHAIN_ID]) {
-		chain = nft_chain_lookup_byid(net, nla[NFTA_RULE_CHAIN_ID]);
+		chain = nft_chain_lookup_byid(net, table, nla[NFTA_RULE_CHAIN_ID]);
 		if (IS_ERR(chain)) {
 			NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN_ID]);
 			return PTR_ERR(chain);
@@ -9661,7 +9663,7 @@  static int nft_verdict_init(const struct nft_ctx *ctx, struct nft_data *data,
 						 tb[NFTA_VERDICT_CHAIN],
 						 genmask);
 		} else if (tb[NFTA_VERDICT_CHAIN_ID]) {
-			chain = nft_chain_lookup_byid(ctx->net,
+			chain = nft_chain_lookup_byid(ctx->net, ctx->table,
 						      tb[NFTA_VERDICT_CHAIN_ID]);
 			if (IS_ERR(chain))
 				return PTR_ERR(chain);