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netfilter: nf_tables: fix device name and prefix match in hook lookup

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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 <void0red@gmail.com>
Closes: https://lore.kernel.org/netfilter-devel/CANE+tVrDeNCHQVmsqkV2ozeBqyE3GtRDMhZgsg1bhw10yGNTRQ@mail.gmail.com/
Fixes: 6d07a28950 ("netfilter: nf_tables: Support wildcard netdev hook specs")
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Fernando Fernandez Mancera 2026-08-27 12:32:56 +02:00 committed by Pablo Neira Ayuso
parent d313499df6
commit 444e4c88c9
1 changed files with 13 additions and 9 deletions
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22
net/netfilter/nf_tables_api.c
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@ -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;