netfilter: nf_tables: reject duplicate device on updates

[ Upstream commit cf5fb87fcdaaaafec55dcc0dc5a9e15ead343973 ]

A chain/flowtable update with duplicated devices in the same batch is
possible. Unfortunately, netdev event path only removes the first
device that is found, leaving unregistered the hook of the duplicated
device.

Check if a duplicated device exists in the transaction batch, bail out
with EEXIST in such case.

WARNING is hit when unregistering the hook:

 [49042.221275] WARNING: CPU: 4 PID: 8425 at net/netfilter/core.c:340 nf_hook_entry_head+0xaa/0x150
 [49042.221375] CPU: 4 UID: 0 PID: 8425 Comm: nft Tainted: G S                  6.16.0+ #170 PREEMPT(full)
 [...]
 [49042.221382] RIP: 0010:nf_hook_entry_head+0xaa/0x150

Fixes: 78d9f48f7f44 ("netfilter: nf_tables: add devices to existing flowtable")
Fixes: b9703ed44ffb ("netfilter: nf_tables: support for adding new devices to an existing netdev chain")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 064f18792d9847726d95e840af7f9ecc2493de79..46ca725d653819cc1a22bdfdc1332ebaa987d748 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2790,6 +2790,7 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
        struct nft_chain *chain = ctx->chain;
        struct nft_chain_hook hook = {};
        struct nft_stats __percpu *stats = NULL;
+       struct nftables_pernet *nft_net;
        struct nft_hook *h, *next;
        struct nf_hook_ops *ops;
        struct nft_trans *trans;
@@ -2832,6 +2833,20 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
                                if (nft_hook_list_find(&basechain->hook_list, h)) {
                                        list_del(&h->list);
                                        nft_netdev_hook_free(h);
+                                       continue;
+                               }
+
+                               nft_net = nft_pernet(ctx->net);
+                               list_for_each_entry(trans, &nft_net->commit_list, list) {
+                                       if (trans->msg_type != NFT_MSG_NEWCHAIN ||
+                                           trans->table != ctx->table ||
+                                           !nft_trans_chain_update(trans))
+                                               continue;
+
+                                       if (nft_hook_list_find(&nft_trans_chain_hooks(trans), h)) {
+                                               nft_chain_release_hook(&hook);
+                                               return -EEXIST;
+                                       }
                                }
                        }
                } else {
@@ -9033,6 +9048,7 @@ static int nft_flowtable_update(struct nft_ctx *ctx, const struct nlmsghdr *nlh,
 {
        const struct nlattr * const *nla = ctx->nla;
        struct nft_flowtable_hook flowtable_hook;
+       struct nftables_pernet *nft_net;
        struct nft_hook *hook, *next;
        struct nf_hook_ops *ops;
        struct nft_trans *trans;
@@ -9049,6 +9065,20 @@ static int nft_flowtable_update(struct nft_ctx *ctx, const struct nlmsghdr *nlh,
                if (nft_hook_list_find(&flowtable->hook_list, hook)) {
                        list_del(&hook->list);
                        nft_netdev_hook_free(hook);
+                       continue;
+               }
+
+               nft_net = nft_pernet(ctx->net);
+               list_for_each_entry(trans, &nft_net->commit_list, list) {
+                       if (trans->msg_type != NFT_MSG_NEWFLOWTABLE ||
+                           trans->table != ctx->table ||
+                           !nft_trans_flowtable_update(trans))
+                               continue;
+
+                       if (nft_hook_list_find(&nft_trans_flowtable_hooks(trans), hook)) {
+                               err = -EEXIST;
+                               goto err_flowtable_update_hook;
+                       }
                }
        }