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 6A22437A857 for ; Thu, 2 Jul 2026 15:36:24 +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=1783006585; cv=none; b=XAl08LHbhEyZ3R8+wlBUHd292HGhbm3IpBeE7h+nkcf/8m0xwylo6zKiVTof4XfkkVeIz5AFoLZX+knc8GQwMIcWMIox231LNWVxVH8dHO/kAysmqeOllnDqADX6ttD0kLYmDs9wVZqf8Pd7ry2jncOmoLt9wW9QKEGzkBc9KhA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783006585; c=relaxed/simple; bh=Ct3iGGq2SMb3lyx9Ud/QhPAWp/h9dObfKsy9YS2pVXs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TYufRquI+Z266xXsKj2UcmeVSujVKzoTXw1OtuP0/DrQiARgTNp+nBuZstDG9et4AOp1yKunP9CqNGD5FmutH1NNvzFHLhGZ203/GYKMAstAZ/LA4dyIge9AMZrU04CbW3Ce0EnDl7J24+lQ5bxWLJ/dkXK2y8a58G0w+0zF9XM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jmwno2h5; 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="jmwno2h5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9CBC01F000E9; Thu, 2 Jul 2026 15:36:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783006584; bh=VWRF9LKNHGFvrhxGvs54A/h1HtwOUVzWHEKT+l6cGw0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jmwno2h5ZKGCPW9nBmqMZRma107Iw3k2Ekbsh++X11+5d8cjMYcwZIddX2GMftUhS KUTt9c5HeIesG4Nudr14RNpUfZjefB38IANqdXIJiKYz+JC2cdpSfl6ndIBmjU0+Iu TCEBF9d0Hvl0pyXzMg8imrxBx3d3YVIRUcgweXL5JwnDmIHb4G81mcoxLSWcKC7prN nYX8vVot3FSe7fgMgNN9LwY/a4IFdXZQxfw35v055dt7LfzaEHAuwQRrwN853xP9py Y5LFNS2XIDX6KmwuK6hINRlS4571LiyWi7pN17lRr2XdJBnywcwQ2WcIehomnjlAuM 2wHhxosPWx/SQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Maoyi Xie , Xiao Liang , Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.10.y] net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink Date: Thu, 2 Jul 2026 11:36:22 -0400 Message-ID: <20260702153622.3533221-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026070222-gently-rally-f7d9@gregkh> References: <2026070222-gently-rally-f7d9@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 e893b1f21913e5..b4869af378d12e 100644 --- a/include/net/rtnetlink.h +++ b/include/net/rtnetlink.h @@ -183,6 +183,8 @@ 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 5603bb4a6cafc2..0da09c19428eaf 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -2024,6 +2024,14 @@ 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 c56848f36298d4..213d29fe190c16 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -1407,6 +1407,9 @@ 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; @@ -1436,6 +1439,9 @@ 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