Commit 994209dd authored Apr 01, 2024 by Pablo Neira Ayuso

netfilter: nf_tables: reject new basechain after table flag update



When dormant flag is toggled, hooks are disabled in the commit phase by
iterating over current chains in table (existing and new).

The following configuration allows for an inconsistent state:

  add table x
  add chain x y { type filter hook input priority 0; }
  add table x { flags dormant; }
  add chain x w { type filter hook input priority 1; }

which triggers the following warning when trying to unregister chain w
which is already unregistered.

[  127.322252] WARNING: CPU: 7 PID: 1211 at net/netfilter/core.c:50                                                                     1 __nf_unregister_net_hook+0x21a/0x260
[...]
[  127.322519] Call Trace:
[  127.322521]  <TASK>
[  127.322524]  ? __warn+0x9f/0x1a0
[  127.322531]  ? __nf_unregister_net_hook+0x21a/0x260
[  127.322537]  ? report_bug+0x1b1/0x1e0
[  127.322545]  ? handle_bug+0x3c/0x70
[  127.322552]  ? exc_invalid_op+0x17/0x40
[  127.322556]  ? asm_exc_invalid_op+0x1a/0x20
[  127.322563]  ? kasan_save_free_info+0x3b/0x60
[  127.322570]  ? __nf_unregister_net_hook+0x6a/0x260
[  127.322577]  ? __nf_unregister_net_hook+0x21a/0x260
[  127.322583]  ? __nf_unregister_net_hook+0x6a/0x260
[  127.322590]  ? __nf_tables_unregister_hook+0x8a/0xe0 [nf_tables]
[  127.322655]  nft_table_disable+0x75/0xf0 [nf_tables]
[  127.322717]  nf_tables_commit+0x2571/0x2620 [nf_tables]

Fixes: 179d9ba5 ("netfilter: nf_tables: fix table flag updates")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

parent 24cea967

net/netfilter/nf_tables_api.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -2449,6 +2449,9 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
		struct nft_stats __percpu *stats = NULL;
		struct nft_chain_hook hook = {};

		if (table->flags & __NFT_TABLE_F_UPDATE)
		return -EINVAL;

		if (flags & NFT_CHAIN_BINDING)
		return -EOPNOTSUPP;