[PATCH v2 4/4] fwctl/mlx5: Externally validate FW commands supplied in fwctl

[Leon Romanovsky <leon@kernel.org>]

From: Chiara Meiohas <cmeiohas@nvidia.com>

fwctl is subsystem which exposes a firmware interface directly to
userspace: it allows userspace to send device specific command
buffers to firmware. fwctl is focused on debugging, configuration
and provisioning of the device.

Call bpf_lsm_fw_validate_cmd() before dispatching the user-provided
firmware command.

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 filter firmware commands based on
their opcode.

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/fwctl/mlx5/main.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/fwctl/mlx5/main.c b/drivers/fwctl/mlx5/main.c
index e86ab703c767a..c49dfa1d172d9 100644
--- a/drivers/fwctl/mlx5/main.c
+++ b/drivers/fwctl/mlx5/main.c
@@ -7,6 +7,7 @@
 #include <linux/mlx5/device.h>
 #include <linux/mlx5/driver.h>
 #include <uapi/fwctl/mlx5.h>
+#include <linux/bpf_lsm.h>
 
 #define mlx5ctl_err(mcdev, format, ...) \
 	dev_err(&mcdev->fwctl.dev, format, ##__VA_ARGS__)
@@ -324,6 +325,15 @@ static void *mlx5ctl_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
 	if (!mlx5ctl_validate_rpc(rpc_in, scope))
 		return ERR_PTR(-EBADMSG);
 
+	/* Enforce the user context for the command */
+	MLX5_SET(mbox_in_hdr, rpc_in, uid, mfd->uctx_uid);
+
+	ret = bpf_lsm_fw_validate_cmd(rpc_in, in_len, &mcdev->fwctl.dev,
+				      FW_CMD_CLASS_FWCTL,
+				      FWCTL_DEVICE_TYPE_MLX5);
+	if (ret)
+		return ERR_PTR(ret);
+
 	/*
 	 * mlx5_cmd_do() copies the input message to its own buffer before
 	 * executing it, so we can reuse the allocation for the output.
@@ -336,8 +346,6 @@ static void *mlx5ctl_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
 			return ERR_PTR(-ENOMEM);
 	}
 
-	/* Enforce the user context for the command */
-	MLX5_SET(mbox_in_hdr, rpc_in, uid, mfd->uctx_uid);
 	ret = mlx5_cmd_do(mcdev->mdev, rpc_in, in_len, rpc_out, *out_len);
 
 	mlx5ctl_dbg(mcdev,

-- 
2.53.0