From 3745242ad1e1c07d5990b33764529eb13565db44 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20G=C3=B6ttsche?= Date: Sun, 2 Mar 2025 17:06:47 +0100 Subject: [PATCH] RDMA/mlx5: Reorder capability check last MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit capable() calls refer to enabled LSMs whether to permit or deny the request. This is relevant in connection with SELinux, where a capability check results in a policy decision and by default a denial message on insufficient permission is issued. It can lead to three undesired cases: 1. A denial message is generated, even in case the operation was an unprivileged one and thus the syscall succeeded, creating noise. 2. To avoid the noise from 1. the policy writer adds a rule to ignore those denial messages, hiding future syscalls, where the task performs an actual privileged operation, leading to hidden limited functionality of that task. 3. To avoid the noise from 1. the policy writer adds a rule to permit the task the requested capability, while it does not need it, violating the principle of least privilege. Signed-off-by: Christian Göttsche Link: https://patch.msgid.link/20250302160657.127253-10-cgoettsche@seltendoof.de Reviewed-by: Serge Hallyn Signed-off-by: Leon Romanovsky --- drivers/infiniband/hw/mlx5/devx.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/infiniband/hw/mlx5/devx.c b/drivers/infiniband/hw/mlx5/devx.c index 4186884c66e10..39304cae5b10e 100644 --- a/drivers/infiniband/hw/mlx5/devx.c +++ b/drivers/infiniband/hw/mlx5/devx.c @@ -136,12 +136,14 @@ int mlx5_ib_devx_create(struct mlx5_ib_dev *dev, bool is_user) return -EINVAL; uctx = MLX5_ADDR_OF(create_uctx_in, in, uctx); - if (is_user && capable(CAP_NET_RAW) && - (MLX5_CAP_GEN(dev->mdev, uctx_cap) & MLX5_UCTX_CAP_RAW_TX)) + if (is_user && + (MLX5_CAP_GEN(dev->mdev, uctx_cap) & MLX5_UCTX_CAP_RAW_TX) && + capable(CAP_NET_RAW)) cap |= MLX5_UCTX_CAP_RAW_TX; - if (is_user && capable(CAP_SYS_RAWIO) && + if (is_user && (MLX5_CAP_GEN(dev->mdev, uctx_cap) & - MLX5_UCTX_CAP_INTERNAL_DEV_RES)) + MLX5_UCTX_CAP_INTERNAL_DEV_RES) && + capable(CAP_SYS_RAWIO)) cap |= MLX5_UCTX_CAP_INTERNAL_DEV_RES; MLX5_SET(create_uctx_in, in, opcode, MLX5_CMD_OP_CREATE_UCTX);