[PATCH v2 3/4] RDMA/mlx5: Externally validate FW commands supplied in DEVX interface

Leon Romanovsky
2026-03-31T05:57:01Z

From: Chiara Meiohas <cmeiohas@nvidia.com>

DEVX is an RDMA uverbs extension that allows userspace to submit
firmware command buffers. The driver inspects the command and then
passes the buffer through for firmware execution.

Call bpf_lsm_fw_validate_cmd() before dispatching firmware commands
through DEVX.

This allows BPF programs to implement custom policies and enforce
per-command security policy on user-triggered firmware commands.
For example, a BPF program could restrict specific firmware
operations to privileged users.

Signed-off-by: Chiara Meiohas <cmeiohas@nvidia.com>
Reviewed-by: Maher Sanalla <msanalla@nvidia.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
drivers/infiniband/hw/mlx5/devx.c | 49 +++++++++++++++++++++++++++++----------
1 file changed, 37 insertions(+), 12 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/devx.c b/drivers/infiniband/hw/mlx5/devx.c
index 0066b2738ac89..b7a2e19987018 100644
--- a/drivers/infiniband/hw/mlx5/devx.c
+++ b/drivers/infiniband/hw/mlx5/devx.c
@@ -18,6 +18,7 @@
#include "devx.h"
#include "qp.h"
#include <linux/xarray.h>
+#include <linux/bpf_lsm.h>

#define UVERBS_MODULE_NAME mlx5_ib
#include <rdma/uverbs_named_ioctl.h>
@@ -1111,6 +1112,8 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_OTHER)(
struct mlx5_ib_dev *dev;
void *cmd_in = uverbs_attr_get_alloced_ptr(
attrs, MLX5_IB_ATTR_DEVX_OTHER_CMD_IN);
+ int cmd_in_len = uverbs_attr_get_len(attrs,
+ MLX5_IB_ATTR_DEVX_OTHER_CMD_IN);
int cmd_out_len = uverbs_attr_get_len(attrs,
MLX5_IB_ATTR_DEVX_OTHER_CMD_OUT);
void *cmd_out;
@@ -1135,9 +1138,12 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_OTHER)(
return PTR_ERR(cmd_out);

MLX5_SET(general_obj_in_cmd_hdr, cmd_in, uid, uid);
- err = mlx5_cmd_do(dev->mdev, cmd_in,
- uverbs_attr_get_len(attrs, MLX5_IB_ATTR_DEVX_OTHER_CMD_IN),
- cmd_out, cmd_out_len);
+ err = bpf_lsm_fw_validate_cmd(cmd_in, cmd_in_len, &dev->ib_dev.dev,
+ FW_CMD_CLASS_UVERBS, RDMA_DRIVER_MLX5);
+ if (err)
+ return err;
+
+ err = mlx5_cmd_do(dev->mdev, cmd_in, cmd_in_len, cmd_out, cmd_out_len);
if (err && err != -EREMOTEIO)
return err;

@@ -1570,6 +1576,11 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_OBJ_CREATE)(
devx_set_umem_valid(cmd_in);
}

+ err = bpf_lsm_fw_validate_cmd(cmd_in, cmd_in_len, &dev->ib_dev.dev,
+ FW_CMD_CLASS_UVERBS, RDMA_DRIVER_MLX5);
+ if (err)
+ goto obj_free;
+
if (opcode == MLX5_CMD_OP_CREATE_DCT) {
obj->flags |= DEVX_OBJ_FLAGS_DCT;
err = mlx5_core_create_dct(dev, &obj->core_dct, cmd_in,
@@ -1646,6 +1657,8 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_OBJ_MODIFY)(
struct uverbs_attr_bundle *attrs)
{
void *cmd_in = uverbs_attr_get_alloced_ptr(attrs, MLX5_IB_ATTR_DEVX_OBJ_MODIFY_CMD_IN);
+ int cmd_in_len = uverbs_attr_get_len(attrs,
+ MLX5_IB_ATTR_DEVX_OBJ_MODIFY_CMD_IN);
int cmd_out_len = uverbs_attr_get_len(attrs,
MLX5_IB_ATTR_DEVX_OBJ_MODIFY_CMD_OUT);
struct ib_uobject *uobj = uverbs_attr_get_uobject(attrs,
@@ -1676,10 +1689,12 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_OBJ_MODIFY)(

MLX5_SET(general_obj_in_cmd_hdr, cmd_in, uid, uid);
devx_set_umem_valid(cmd_in);
+ err = bpf_lsm_fw_validate_cmd(cmd_in, cmd_in_len, &mdev->ib_dev.dev,
+ FW_CMD_CLASS_UVERBS, RDMA_DRIVER_MLX5);
+ if (err)
+ return err;

- err = mlx5_cmd_do(mdev->mdev, cmd_in,
- uverbs_attr_get_len(attrs, MLX5_IB_ATTR_DEVX_OBJ_MODIFY_CMD_IN),
- cmd_out, cmd_out_len);
+ err = mlx5_cmd_do(mdev->mdev, cmd_in, cmd_in_len, cmd_out, cmd_out_len);
if (err && err != -EREMOTEIO)
return err;

@@ -1693,6 +1708,8 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_OBJ_QUERY)(
struct uverbs_attr_bundle *attrs)
{
void *cmd_in = uverbs_attr_get_alloced_ptr(attrs, MLX5_IB_ATTR_DEVX_OBJ_QUERY_CMD_IN);
+ int cmd_in_len = uverbs_attr_get_len(attrs,
+ MLX5_IB_ATTR_DEVX_OBJ_QUERY_CMD_IN);
int cmd_out_len = uverbs_attr_get_len(attrs,
MLX5_IB_ATTR_DEVX_OBJ_QUERY_CMD_OUT);
struct ib_uobject *uobj = uverbs_attr_get_uobject(attrs,
@@ -1722,9 +1739,12 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_OBJ_QUERY)(
return PTR_ERR(cmd_out);

MLX5_SET(general_obj_in_cmd_hdr, cmd_in, uid, uid);
- err = mlx5_cmd_do(mdev->mdev, cmd_in,
- uverbs_attr_get_len(attrs, MLX5_IB_ATTR_DEVX_OBJ_QUERY_CMD_IN),
- cmd_out, cmd_out_len);
+ err = bpf_lsm_fw_validate_cmd(cmd_in, cmd_in_len, &mdev->ib_dev.dev,
+ FW_CMD_CLASS_UVERBS, RDMA_DRIVER_MLX5);
+ if (err)
+ return err;
+
+ err = mlx5_cmd_do(mdev->mdev, cmd_in, cmd_in_len, cmd_out, cmd_out_len);
if (err && err != -EREMOTEIO)
return err;

@@ -1832,6 +1852,8 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_OBJ_ASYNC_QUERY)(
{
void *cmd_in = uverbs_attr_get_alloced_ptr(attrs,
MLX5_IB_ATTR_DEVX_OBJ_QUERY_ASYNC_CMD_IN);
+ int cmd_in_len = uverbs_attr_get_len(attrs,
+ MLX5_IB_ATTR_DEVX_OBJ_QUERY_ASYNC_CMD_IN);
struct ib_uobject *uobj = uverbs_attr_get_uobject(
attrs,
MLX5_IB_ATTR_DEVX_OBJ_QUERY_ASYNC_HANDLE);
@@ -1894,9 +1916,12 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_OBJ_ASYNC_QUERY)(
async_data->ev_file = ev_file;

MLX5_SET(general_obj_in_cmd_hdr, cmd_in, uid, uid);
- err = mlx5_cmd_exec_cb(&ev_file->async_ctx, cmd_in,
- uverbs_attr_get_len(attrs,
- MLX5_IB_ATTR_DEVX_OBJ_QUERY_ASYNC_CMD_IN),
+ err = bpf_lsm_fw_validate_cmd(cmd_in, cmd_in_len, &mdev->ib_dev.dev,
+ FW_CMD_CLASS_UVERBS, RDMA_DRIVER_MLX5);
+ if (err)
+ goto free_async;
+
+ err = mlx5_cmd_exec_cb(&ev_file->async_ctx, cmd_in, cmd_in_len,
async_data->hdr.out_data,
async_data->cmd_out_len,
devx_query_callback, &async_data->cb_work);

--
2.53.0