From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [91.216.245.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 74C6C340D97; Tue, 2 Sep 2025 18:59:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.216.245.30 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756839557; cv=none; b=SwUCFy7fg7YPqS7nhPIqLoZSR+40hNVf8238p5uJxjdABTER1nFDxEXl4HN4FNrtZgqydfZ1xQev1Wu3AJE3+/w4TK+cD1fZsKSH1DC/YdwYp47CJdd54cz+TIFrVWMqEhfaQ/74EGNIRc5Q2mEu+4K3GfookVKGcpz6tbLezSE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756839557; c=relaxed/simple; bh=uJQFwJTuvfeIEy4YnJz/3qaOZZLyJo9xvYPfQP+2f2k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=R2GskdbRte3D6NuKy3ToX5jxeCr6hAmPfIHSXgBoJt2YNtlAkDQ4YWmx9SkyLEdsgitceHjomv0HS4tfINeX0dDb6xtx+a5Z1qCI93wnu8RNuqpylVYIOh2cVrF+p0DuS+l92PXiBZJJ9gZyVn31p9E0Ig3T8E99aMbJ2EYjWg4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de; spf=pass smtp.mailfrom=Chamillionaire.breakpoint.cc; arc=none smtp.client-ip=91.216.245.30 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=Chamillionaire.breakpoint.cc Received: by Chamillionaire.breakpoint.cc (Postfix, from userid 1003) id 7266A60288; Tue, 2 Sep 2025 20:59:13 +0200 (CEST) From: Florian Westphal To: Cc: Paolo Abeni , "David S. Miller" , Eric Dumazet , Jakub Kicinski , , pablo@netfilter.org Subject: [PATCH net 2/2] netfilter: nf_tables: Introduce NFTA_DEVICE_PREFIX Date: Tue, 2 Sep 2025 20:58:55 +0200 Message-ID: <20250902185855.25919-3-fw@strlen.de> X-Mailer: git-send-email 2.49.1 In-Reply-To: <20250902185855.25919-1-fw@strlen.de> References: <20250902185855.25919-1-fw@strlen.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Phil Sutter This new attribute is supposed to be used instead of NFTA_DEVICE_NAME for simple wildcard interface specs. It holds a NUL-terminated string representing an interface name prefix to match on. While kernel code to distinguish full names from prefixes in NFTA_DEVICE_NAME is simpler than this solution, reusing the existing attribute with different semantics leads to confusion between different versions of kernel and user space though: * With old kernels, wildcards submitted by user space are accepted yet silently treated as regular names. * With old user space, wildcards submitted by kernel may cause crashes since libnftnl expects NUL-termination when there is none. Using a distinct attribute type sanitizes these situations as the receiving part detects and rejects the unexpected attribute nested in *_HOOK_DEVS attributes. Fixes: 6d07a289504a ("netfilter: nf_tables: Support wildcard netdev hook specs") Signed-off-by: Phil Sutter Signed-off-by: Florian Westphal --- include/uapi/linux/netfilter/nf_tables.h | 2 ++ net/netfilter/nf_tables_api.c | 42 +++++++++++++++++------- 2 files changed, 33 insertions(+), 11 deletions(-) diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h index 2beb30be2c5f..8e0eb832bc01 100644 --- a/include/uapi/linux/netfilter/nf_tables.h +++ b/include/uapi/linux/netfilter/nf_tables.h @@ -1784,10 +1784,12 @@ enum nft_synproxy_attributes { * enum nft_device_attributes - nf_tables device netlink attributes * * @NFTA_DEVICE_NAME: name of this device (NLA_STRING) + * @NFTA_DEVICE_PREFIX: device name prefix, a simple wildcard (NLA_STRING) */ enum nft_devices_attributes { NFTA_DEVICE_UNSPEC, NFTA_DEVICE_NAME, + NFTA_DEVICE_PREFIX, __NFTA_DEVICE_MAX }; #define NFTA_DEVICE_MAX (__NFTA_DEVICE_MAX - 1) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 58c5425d61c2..c1082de09656 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -1959,6 +1959,18 @@ 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) +{ + return strlen(hook->ifname) >= hook->ifnamelen; +} + +static int nft_nla_put_hook_dev(struct sk_buff *skb, struct nft_hook *hook) +{ + int attr = hook_is_prefix(hook) ? NFTA_DEVICE_PREFIX : NFTA_DEVICE_NAME; + + return nla_put_string(skb, attr, hook->ifname); +} + static int nft_dump_basechain_hook(struct sk_buff *skb, const struct net *net, int family, const struct nft_base_chain *basechain, @@ -1990,16 +2002,15 @@ static int nft_dump_basechain_hook(struct sk_buff *skb, if (!first) first = hook; - if (nla_put(skb, NFTA_DEVICE_NAME, - hook->ifnamelen, hook->ifname)) + if (nft_nla_put_hook_dev(skb, hook)) goto nla_put_failure; n++; } nla_nest_end(skb, nest_devs); if (n == 1 && - nla_put(skb, NFTA_HOOK_DEV, - first->ifnamelen, first->ifname)) + !hook_is_prefix(first) && + nla_put_string(skb, NFTA_HOOK_DEV, first->ifname)) goto nla_put_failure; } nla_nest_end(skb, nest); @@ -2310,7 +2321,8 @@ void nf_tables_chain_destroy(struct nft_chain *chain) } static struct nft_hook *nft_netdev_hook_alloc(struct net *net, - const struct nlattr *attr) + const struct nlattr *attr, + bool prefix) { struct nf_hook_ops *ops; struct net_device *dev; @@ -2327,7 +2339,8 @@ static struct nft_hook *nft_netdev_hook_alloc(struct net *net, if (err < 0) goto err_hook_free; - hook->ifnamelen = nla_len(attr); + /* include the terminating NUL-char when comparing non-prefixes */ + hook->ifnamelen = strlen(hook->ifname) + !prefix; /* nf_tables_netdev_event() is called under rtnl_mutex, this is * indirectly serializing all the other holders of the commit_mutex with @@ -2374,14 +2387,22 @@ static int nf_tables_parse_netdev_hooks(struct net *net, struct nft_hook *hook, *next; const struct nlattr *tmp; int rem, n = 0, err; + bool prefix; nla_for_each_nested(tmp, attr, rem) { - if (nla_type(tmp) != NFTA_DEVICE_NAME) { + switch (nla_type(tmp)) { + case NFTA_DEVICE_NAME: + prefix = false; + break; + case NFTA_DEVICE_PREFIX: + prefix = true; + break; + default: err = -EINVAL; goto err_hook; } - hook = nft_netdev_hook_alloc(net, tmp); + hook = nft_netdev_hook_alloc(net, tmp, prefix); if (IS_ERR(hook)) { NL_SET_BAD_ATTR(extack, tmp); err = PTR_ERR(hook); @@ -2427,7 +2448,7 @@ static int nft_chain_parse_netdev(struct net *net, struct nlattr *tb[], int err; if (tb[NFTA_HOOK_DEV]) { - hook = nft_netdev_hook_alloc(net, tb[NFTA_HOOK_DEV]); + hook = nft_netdev_hook_alloc(net, tb[NFTA_HOOK_DEV], false); if (IS_ERR(hook)) { NL_SET_BAD_ATTR(extack, tb[NFTA_HOOK_DEV]); return PTR_ERR(hook); @@ -9458,8 +9479,7 @@ static int nf_tables_fill_flowtable_info(struct sk_buff *skb, struct net *net, list_for_each_entry_rcu(hook, hook_list, list, lockdep_commit_lock_is_held(net)) { - if (nla_put(skb, NFTA_DEVICE_NAME, - hook->ifnamelen, hook->ifname)) + if (nft_nla_put_hook_dev(skb, hook)) goto nla_put_failure; } nla_nest_end(skb, nest_devs); -- 2.49.1