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Tue, 18 Aug 2026 10:18:59 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id qYSbD5MxhGpNDAAAD6G6ig (envelope-from ); Tue, 18 Aug 2026 10:18:59 +0000 From: Fernando Fernandez Mancera To: netfilter-devel@vger.kernel.org Cc: pablo@netfilter.org, fw@strlen.de, phil@nwl.cc, coreteam@netfilter.org, Fernando Fernandez Mancera , Wei Fang Subject: [PATCH nf] netfilter: nf_tables: fix device name and prefix match in hook lookup Date: Tue, 18 Aug 2026 12:18:25 +0200 Message-ID: <20260818101825.8213-1-fmancera@suse.de> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: netfilter-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-2.79 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.19)[-0.966]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_SEVEN(0.00)[7]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[netfilter.org,strlen.de,nwl.cc,suse.de,gmail.com]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,suse.de:email,imap1.dmz-prg2.suse.org:helo]; RCVD_COUNT_TWO(0.00)[2]; FREEMAIL_ENVRCPT(0.00)[gmail.com] X-Spam-Flag: NO X-Spam-Score: -2.79 X-Spam-Level: Currently, a netdev chain or flowtable hooked to a device prefix can be unintentionally deleted or updated 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. 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 --- net/netfilter/nf_tables_api.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index af357f6c5070..e2b18c4722fc 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -1973,7 +1973,7 @@ static int nft_dump_stats(struct sk_buff *skb, struct nft_stats __percpu *stats) return -ENOSPC; } -static bool hook_is_prefix(struct nft_hook *hook) +static bool hook_is_prefix(const struct nft_hook *hook) { return strlen(hook->ifname) >= hook->ifnamelen; } @@ -2440,8 +2440,11 @@ static struct nft_hook *nft_hook_list_find(struct list_head *hook_list, struct nft_hook *hook; list_for_each_entry(hook, hook_list, list) { - if (!strncmp(hook->ifname, this->ifname, - min(hook->ifnamelen, this->ifnamelen))) { + if (hook_is_prefix(hook) != hook_is_prefix(this)) + continue; + if (hook->ifnamelen != this->ifnamelen) + continue; + if (!strncmp(hook->ifname, this->ifname, hook->ifnamelen)) { if (hook->flags & NFT_HOOK_REMOVE) continue; -- 2.55.0