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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Mina Almasry , Stanislav Fomichev , Donald Hunter , Simon Horman , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Doruk Tan Ozturk Subject: [PATCH net] netdev: require admin permission for the bind-tx netlink operation Date: Fri, 24 Jul 2026 17:01:56 +0200 Message-ID: <20260724150156.72816-1-doruk@0sec.ai> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The netdev generic-netlink bind-rx operation (NETDEV_CMD_BIND_RX) is flagged uns-admin-perm, so binding a dmabuf into a device RX datapath requires CAP_NET_ADMIN. The symmetric bind-tx operation (NETDEV_CMD_BIND_TX), added later, was given no permission flag. The netdev family sets netnsok and has no pre_doit, and netdev_nl_bind_tx_doit() performs no capability check, so any unprivileged process can bind a dmabuf into a netmem-TX-capable device TX datapath. net_devmem_bind_dmabuf() attaches and DMA-maps the caller-supplied dmabuf to the device and installs TX device-memory state, the same class of privileged device operation that bind-rx restricts. Gate bind-tx behind uns-admin-perm to match bind-rx. Found by 0sec (https://0sec.ai). Fixes: 8802087d20c0 ("net: devmem: TCP tx netlink api") Cc: stable@vger.kernel.org Assisted-by: 0sec:multi-model Signed-off-by: Doruk Tan Ozturk --- Documentation/netlink/specs/netdev.yaml | 1 + net/core/netdev-genl-gen.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlin= k/specs/netdev.yaml index 5f143da7458c..6c374aca3d27 100644 --- a/Documentation/netlink/specs/netdev.yaml +++ b/Documentation/netlink/specs/netdev.yaml @@ -832,6 +832,7 @@ operations: name: bind-tx doc: Bind dmabuf to netdev for TX attribute-set: dmabuf + flags: [uns-admin-perm] do: request: attributes: diff --git a/net/core/netdev-genl-gen.c b/net/core/netdev-genl-gen.c index d18c89b5a6c7..07d87445eb22 100644 --- a/net/core/netdev-genl-gen.c +++ b/net/core/netdev-genl-gen.c @@ -234,7 +234,7 @@ static const struct genl_split_ops netdev_nl_ops[] =3D { .doit =3D netdev_nl_bind_tx_doit, .policy =3D netdev_bind_tx_nl_policy, .maxattr =3D NETDEV_A_DMABUF_FD, - .flags =3D GENL_CMD_CAP_DO, + .flags =3D GENL_UNS_ADMIN_PERM | GENL_CMD_CAP_DO, }, { .cmd =3D NETDEV_CMD_QUEUE_CREATE, --=20 2.43.0