From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 C1F53353A69 for ; Thu, 2 Jul 2026 15:11:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783005067; cv=none; b=phYT1rxeZgntyITx5VSd8a29/j7Bi54YpZy92AfA27lH2onlFqC/AuZ3cTLfvKB7Gfx3mL2+zYlHfJ6z6J9TCrnbEpB+LfPDYLBtU11jm7l1JTpzVA28tOWhjOk9y1ciMVaaR+/vy/WC7GVkXm1E50K2CGKsw90lmylUmwoyh6A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783005067; c=relaxed/simple; bh=OaS5jdR6a3zwejP3LIaPmc7V7w788YjYyPyjzR8phEw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jlYFoCF0bYHdVdWrm+3lWPohPQBH91vM9RxBtIovgaJaUIcY9Y47QgtDjzclyglxBxqZ+CKUl7iViBfYiOU/kueN/HQ3Z6V7aIoQ1/uXNy+TyxXwpabB0sbQ8yh2ldX+rJihEt7558W8dFIscy4a7Y7LRENzckfwHfkAK6XptXE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CDfrVnvu; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CDfrVnvu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F37961F000E9; Thu, 2 Jul 2026 15:11:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783005066; bh=SVpVf9myb59VQm0mlMhKgh0sPf4gBupxxUt5SrM4PFE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CDfrVnvu1G1TlkyY1ib0mjl7jlcJGEUuQVKhd5JreOaIqHCXn6JI1m2PlyLwaufZ4 ggzxlvMN0B+oK6prA2tHdt1BdNPQursI65QyW7t3cnD8KY4M03rKap9MNH6FjFcfq+ K9oTd+5cG/rHO3+edrWR7bcYBC6rb0fCenNyOj1jXmDNZUufYaUpJ+kZs+nLj2uuOt NARKoxxUR9u3+D82Wi0Yn7xrALuABuLhl7kuPYASm+vhC1GRmqtW6fNiyaPmAVZcGn S2W7fW+2D1uTbivRDQOFiAMEgglfg2DZ6DUvw+QKs8cDCUVtEvVu9GCGvRilKyLrMq /lG9S8Uuk/8VA== From: Sasha Levin To: stable@vger.kernel.org Cc: Maoyi Xie , Xiao Liang , Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1.y] net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink Date: Thu, 2 Jul 2026 11:11:04 -0400 Message-ID: <20260702151104.3512866-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026070221-oblivious-crayfish-1017@gregkh> References: <2026070221-oblivious-crayfish-1017@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Maoyi Xie [ Upstream commit 8165f7ff57d9667d2bb477ef6af83ede7fed4ad7 ] A tunnel changelink() operates on at most two netns, dev_net(dev) and the tunnel link netns t->net. They differ once the device is created in or moved to a netns other than the one the request runs in. The rtnl changelink path checks CAP_NET_ADMIN only against dev_net(dev), so a caller privileged there but not in t->net can rewrite a tunnel that lives in t->net. Add rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in net/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is skipped when the link netns is dev_net(dev), where the rtnl path already checked it. The other patches in this series use the same helper. Gate ipgre_changelink() and erspan_changelink() with it, at the top of the op before any attribute is parsed, because the parsers update live tunnel fields first. ipgre_netlink_parms() sets t->collect_md before ip_tunnel_changelink() runs. Commit 8b484efd5cb4 ("ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().") added the same check on the ioctl path. This adds it on RTM_NEWLINK. Reported-by: Xiao Liang Closes: https://lore.kernel.org/netdev/CABAhCOSzP1vaThGV35_VnsRCb=87_CPjPVsTHbq905k8A+BuUg@mail.gmail.com/ Fixes: b57708add314 ("gre: add x-netns support") Cc: stable@vger.kernel.org Signed-off-by: Maoyi Xie Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260612085941.3158249-2-maoyixie.tju@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/rtnetlink.h | 2 ++ net/core/rtnetlink.c | 8 ++++++++ net/ipv4/ip_gre.c | 6 ++++++ 3 files changed, 16 insertions(+) diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h index 0bd400be3f8d9f..983f01bf1bd6ba 100644 --- a/include/net/rtnetlink.h +++ b/include/net/rtnetlink.h @@ -210,6 +210,8 @@ int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm, int rtnl_nla_parse_ifinfomsg(struct nlattr **tb, const struct nlattr *nla_peer, struct netlink_ext_ack *exterr); struct net *rtnl_get_net_ns_capable(struct sock *sk, int netnsid); +bool rtnl_dev_link_net_capable(const struct net_device *dev, + const struct net *link_net); #define MODULE_ALIAS_RTNL_LINK(kind) MODULE_ALIAS("rtnl-link-" kind) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index a4e017c2cbf213..b97d348a5b2a93 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -2110,6 +2110,14 @@ struct net *rtnl_get_net_ns_capable(struct sock *sk, int netnsid) } EXPORT_SYMBOL_GPL(rtnl_get_net_ns_capable); +bool rtnl_dev_link_net_capable(const struct net_device *dev, + const struct net *link_net) +{ + return net_eq(link_net, dev_net(dev)) || + ns_capable(link_net->user_ns, CAP_NET_ADMIN); +} +EXPORT_SYMBOL_GPL(rtnl_dev_link_net_capable); + static int rtnl_valid_dump_ifinfo_req(const struct nlmsghdr *nlh, bool strict_check, struct nlattr **tb, struct netlink_ext_ack *extack) diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 2c1228ddaa22f7..b635d2fedd2dbd 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -1406,6 +1406,9 @@ static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[], struct ip_tunnel_parm p; int err; + if (!rtnl_dev_link_net_capable(dev, t->net)) + return -EPERM; + err = ipgre_newlink_encap_setup(dev, data); if (err) return err; @@ -1435,6 +1438,9 @@ static int erspan_changelink(struct net_device *dev, struct nlattr *tb[], struct ip_tunnel_parm p; int err; + if (!rtnl_dev_link_net_capable(dev, t->net)) + return -EPERM; + err = ipgre_newlink_encap_setup(dev, data); if (err) return err; -- 2.53.0