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Wed, 19 Aug 2026 01:35:57 -0700 (PDT) Received: from SurHub.localdomain ([196.188.112.82]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-499a9e09e87sm29215205e9.4.2026.08.19.01.35.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Aug 2026 01:35:56 -0700 (PDT) From: Abdifatah Suruur To: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, quic_subashab@quicinc.com, quic_stranche@quicinc.com, doruk@0sec.ai, kuba@kernel.org Subject: [PATCH net v2] net: qualcomm: rmnet: require CAP_NET_ADMIN in the real device netns for changelink Date: Wed, 19 Aug 2026 11:35:53 +0300 Message-ID: <20260819083553.1134-1-suruurism@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260813174727.14857-1-suruurism@gmail.com> References: <20260813174727.14857-1-suruurism@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A changelink() on an rmnet device mutates the rmnet port state attached to the real device (endpoint mux table, port->data_format and, via rmnet_vnd_update_dev_mtu(), the real device MTU). The real device may live in a different netns than the rmnet device (rmnet_newlink() resolves it in link_net), but the rtnl path only checks CAP_NET_ADMIN against dev_net(dev). A caller privileged only in the rmnet device's netns can therefore rewrite the shared cellular data-path state owned by another netns. Gate rmnet_changelink() with rtnl_dev_link_net_capable(), matching the "require CAP_NET_ADMIN in the device netns for changelink" series (vxlan/geneve, CVE-2026-68432). Fixes: 2abb5792387e ("net: qualcomm: rmnet: Allow configuration updates to existing devices") Cc: stable@vger.kernel.org Signed-off-by: Abdifatah Suruur --- v2: - drop Reported-by: (implied for the author), per Jakub Kicinski --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c @@ -312,6 +312,14 @@ if (!rmnet_is_real_dev_registered(real_dev)) return -ENODEV; + /* + * The rtnl path only checks CAP_NET_ADMIN against dev_net(dev), + * but the port state mutated below is attached to real_dev, which + * may live in a different netns. + */ + if (!rtnl_dev_link_net_capable(dev, dev_net(real_dev))) + return -EPERM; + port = rmnet_get_port_rtnl(real_dev); if (data[IFLA_RMNET_MUX_ID]) {