RDMA/mlx5: Reorder capability check last

JIRA: https://issues.redhat.com/browse/RHEL-72227
JIRA: https://issues.redhat.com/browse/RHEL-73520
Upstream-status: v6.15-rc1

commit 3745242
Author: Christian Göttsche <cgzones@googlemail.com>
Date:   Sun Mar 2 17:06:47 2025 +0100

    RDMA/mlx5: Reorder capability check last

    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 <cgzones@googlemail.com>
    Link: https://patch.msgid.link/20250302160657.127253-10-cgoettsche@seltendoof.de
    Reviewed-by: Serge Hallyn <serge@hallyn.com>
    Signed-off-by: Leon Romanovsky <leon@kernel.org>

Signed-off-by: Benjamin Poirier <bpoirier@redhat.com>

Author: Benjamin Poirier

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);