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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: David Ahern , Kuniyuki Iwashima , Xiao Liang , Steffen Klassert , Herbert Xu , Simon Horman , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH net v5 2/7] net: ipip: require CAP_NET_ADMIN in the device netns for changelink Date: Thu, 11 Jun 2026 14:28:09 +0800 Message-Id: <20260611062814.2528793-3-maoyixie.tju@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260611062814.2528793-1-maoyixie.tju@gmail.com> References: <20260611062814.2528793-1-maoyixie.tju@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ipip_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. Gate ipip_changelink() on rtnl_dev_link_net_capable() at its top, before any attribute is parsed. Reported-by: Xiao Liang Closes: https://lore.kernel.org/netdev/CABAhCOSzP1vaThGV35_VnsRCb=87_CPjPVsTHbq905k8A+BuUg@mail.gmail.com/ Fixes: d0f418516022 ("net, ip_tunnel: fix namespaces move") Cc: stable@vger.kernel.org Signed-off-by: Maoyi Xie --- net/ipv4/ipip.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c index ff95b1b9908e..e7378569bd5b 100644 --- a/net/ipv4/ipip.c +++ b/net/ipv4/ipip.c @@ -494,6 +494,9 @@ static int ipip_changelink(struct net_device *dev, struct nlattr *tb[], bool collect_md; __u32 fwmark = t->fwmark; + if (!rtnl_dev_link_net_capable(dev, t->net)) + return -EPERM; + if (ip_tunnel_netlink_encap_parms(data, &ipencap)) { int err = ip_tunnel_encap_setup(t, &ipencap); -- 2.34.1