diff mbox series

[v2,11/11] infiniband: reorder capability check last

Message ID 20250302160657.127253-10-cgoettsche@seltendoof.de (mailing list archive)
State Handled Elsewhere
Headers show
Series [v2,01/11] coccinelle: Add script to reorder capable() calls | expand

Commit Message

Christian Göttsche March 2, 2025, 4:06 p.m. UTC 
From: Christian Göttsche <cgzones@googlemail.com>

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>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
---
 drivers/infiniband/hw/mlx5/devx.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Comments

Leon Romanovsky March 3, 2025, 7:04 p.m. UTC | #1 
On Sun, Mar 02, 2025 at 05:06:47PM +0100, Christian Göttsche wrote:
> From: Christian Göttsche <cgzones@googlemail.com>
> 
> 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>
> Reviewed-by: Serge Hallyn <serge@hallyn.com>
> ---
>  drivers/infiniband/hw/mlx5/devx.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)

Thanks, applied.
https://web.git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/commit/?h=wip/leon-for-next&id=3745242ad1e1c07d5990b33764529eb13565db44
diff mbox series

Patch

diff --git a/drivers/infiniband/hw/mlx5/devx.c b/drivers/infiniband/hw/mlx5/devx.c
index 4186884c66e1..39304cae5b10 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);