From 444e4c88c9c62a3d823069006563513fe7d5aa66 Mon Sep 17 00:00:00 2001 From: Fernando Fernandez Mancera Date: Thu, 27 Aug 2026 12:32:56 +0200 Subject: [PATCH] netfilter: nf_tables: fix device name and prefix match in hook lookup Currently, a netdev chain or flowtable hooked to a device prefix can be unintentionally deleted by a control-plane request targeting an exact device name or even a shorter one due to the usage of min() to calculate the length to match. Fix this by making sure an exact device match never matches a prefix and that both the target and the candidate have the same length during delete operation. The add and update paths retain the existing overlap matching to prevent a single device from matching multiple hooks. Reported-by: Wei Fang Closes: https://lore.kernel.org/netfilter-devel/CANE+tVrDeNCHQVmsqkV2ozeBqyE3GtRDMhZgsg1bhw10yGNTRQ@mail.gmail.com/ Fixes: 6d07a289504a ("netfilter: nf_tables: Support wildcard netdev hook specs") Signed-off-by: Fernando Fernandez Mancera Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 31fbd5a28937..c0b754a2d45b 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -2440,11 +2440,14 @@ static struct nft_hook *nft_netdev_hook_alloc(struct net *net, } static struct nft_hook *nft_hook_list_find(struct list_head *hook_list, - const struct nft_hook *this) + const struct nft_hook *this, + bool strict) { struct nft_hook *hook; list_for_each_entry(hook, hook_list, list) { + if (strict && hook->ifnamelen != this->ifnamelen) + continue; if (!strncmp(hook->ifname, this->ifname, min(hook->ifnamelen, this->ifnamelen))) { if (hook->flags & NFT_HOOK_REMOVE) @@ -2486,7 +2489,7 @@ static int nf_tables_parse_netdev_hooks(struct net *net, err = PTR_ERR(hook); goto err_hook; } - if (nft_hook_list_find(hook_list, hook)) { + if (nft_hook_list_find(hook_list, hook, false)) { NL_SET_BAD_ATTR(extack, tmp); nft_netdev_hook_free(hook); err = -EEXIST; @@ -2943,7 +2946,7 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy, ops->hook = basechain->ops.hook; } - if (nft_hook_list_find(&basechain->hook_list, h)) { + if (nft_hook_list_find(&basechain->hook_list, h, false)) { list_del(&h->list); nft_netdev_hook_free(h); continue; @@ -2956,7 +2959,8 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy, !nft_trans_chain_update(trans)) continue; - if (nft_hook_list_find(&nft_trans_chain_hooks(trans), h)) { + if (nft_hook_list_find(&nft_trans_chain_hooks(trans), + h, false)) { nft_chain_release_hook(&hook); return -EEXIST; } @@ -3257,7 +3261,7 @@ static int nft_delchain_hook(struct nft_ctx *ctx, return err; list_for_each_entry(this, &chain_hook.list, list) { - hook = nft_hook_list_find(&basechain->hook_list, this); + hook = nft_hook_list_find(&basechain->hook_list, this, true); if (!hook) { err = -ENOENT; goto err_chain_del_hook; @@ -9053,7 +9057,7 @@ static int nft_register_flowtable_net_hooks(struct net *net, if (!nft_is_active_next(net, ft)) continue; - if (nft_hook_list_find(&ft->hook_list, hook)) { + if (nft_hook_list_find(&ft->hook_list, hook, false)) { err = -EEXIST; goto err_unregister_net_hooks; } @@ -9130,7 +9134,7 @@ static int nft_flowtable_update(struct nft_ctx *ctx, const struct nlmsghdr *nlh, return err; list_for_each_entry_safe(hook, next, &flowtable_hook.list, list) { - if (nft_hook_list_find(&flowtable->hook_list, hook)) { + if (nft_hook_list_find(&flowtable->hook_list, hook, false)) { list_del(&hook->list); nft_netdev_hook_free(hook); continue; @@ -9143,7 +9147,7 @@ static int nft_flowtable_update(struct nft_ctx *ctx, const struct nlmsghdr *nlh, !nft_trans_flowtable_update(trans)) continue; - if (nft_hook_list_find(&nft_trans_flowtable_hooks(trans), hook)) { + if (nft_hook_list_find(&nft_trans_flowtable_hooks(trans), hook, false)) { err = -EEXIST; goto err_flowtable_update_hook; } @@ -9363,7 +9367,7 @@ static int nft_delflowtable_hook(struct nft_ctx *ctx, return err; list_for_each_entry(this, &flowtable_hook.list, list) { - hook = nft_hook_list_find(&flowtable->hook_list, this); + hook = nft_hook_list_find(&flowtable->hook_list, this, true); if (!hook) { err = -ENOENT; goto err_flowtable_del_hook;