media: v4l2-core: Introduce v4l2-isp.c

Add to the V4L2 framework helper functions to support drivers when
validating a buffer of V4L2 ISP parameters.

Driver shall use v4l2_isp_params_validate_buffer_size() to verify the
size correctness of the data received from userspace, and after having
copied the data to a kernel-only memory location, complete the
validation by calling v4l2_isp_params_validate_buffer().

Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Michael Riesch <michael.riesch@collabora.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

MAINTAINERS

@@ -26890,6 +26890,8 @@ M:	Jacopo Mondi <jacopo.mondi@ideasonboard.com>
 L:	linux-media@vger.kernel.org
 S:	Maintained
 F:	Documentation/userspace-api/media/v4l/v4l2-isp.rst
+F:	drivers/media/v4l2-core/v4l2-isp.c
+F:	include/media/v4l2-isp.h
 F:	include/uapi/linux/media/v4l2-isp.h
 
 VF610 NAND DRIVER

drivers/media/v4l2-core/Kconfig

@@ -82,3 +82,7 @@ config V4L2_CCI_I2C
 	depends on I2C
 	select REGMAP_I2C
 	select V4L2_CCI
+
+config V4L2_ISP
+	tristate
+	depends on VIDEOBUF2_CORE

drivers/media/v4l2-core/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_V4L2_CCI) += v4l2-cci.o
 obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash-led-class.o
 obj-$(CONFIG_V4L2_FWNODE) += v4l2-fwnode.o
 obj-$(CONFIG_V4L2_H264) += v4l2-h264.o
+obj-$(CONFIG_V4L2_ISP) += v4l2-isp.o
 obj-$(CONFIG_V4L2_JPEG_HELPER) += v4l2-jpeg.o
 obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
 obj-$(CONFIG_V4L2_VP9) += v4l2-vp9.o

drivers/media/v4l2-core/v4l2-isp.c

@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Video4Linux2 generic ISP parameters and statistics support
+ *
+ * Copyright (C) 2025 Ideas On Board Oy
+ * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
+ */
+
+#include <media/v4l2-isp.h>
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+
+#include <media/videobuf2-core.h>
+
+int v4l2_isp_params_validate_buffer_size(struct device *dev,
+					 struct vb2_buffer *vb,
+					 size_t max_size)
+{
+	size_t header_size = offsetof(struct v4l2_isp_params_buffer, data);
+	size_t payload_size = vb2_get_plane_payload(vb, 0);
+
+	/* Payload size can't be greater than the destination buffer size */
+	if (payload_size > max_size) {
+		dev_dbg(dev, "Payload size is too large: %zu\n", payload_size);
+		return -EINVAL;
+	}
+
+	/* Payload size can't be smaller than the header size */
+	if (payload_size < header_size) {
+		dev_dbg(dev, "Payload size is too small: %zu\n", payload_size);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_isp_params_validate_buffer_size);
+
+int v4l2_isp_params_validate_buffer(struct device *dev, struct vb2_buffer *vb,
+				    const struct v4l2_isp_params_buffer *buffer,
+				    const struct v4l2_isp_params_block_info *info,
+				    size_t num_blocks)
+{
+	size_t header_size = offsetof(struct v4l2_isp_params_buffer, data);
+	size_t payload_size = vb2_get_plane_payload(vb, 0);
+	size_t block_offset = 0;
+	size_t buffer_size;
+
+	/*
+	 * Currently only the first version of the V4L2 ISP parameters format is
+	 * supported. We accept both V0 and V1 to support existing drivers
+	 * compatible with V4L2 ISP that use either 0 or 1 as their "first
+	 * version" identifiers.
+	 */
+	if (buffer->version != V4L2_ISP_PARAMS_VERSION_V0 &&
+	    buffer->version != V4L2_ISP_PARAMS_VERSION_V1) {
+		dev_dbg(dev,
+			"Unsupported V4L2 ISP parameters format version: %u\n",
+			buffer->version);
+		return -EINVAL;
+	}
+
+	/* Validate the size reported in the header */
+	buffer_size = header_size + buffer->data_size;
+	if (buffer_size != payload_size) {
+		dev_dbg(dev, "Data size %zu and payload size %zu are different\n",
+			buffer_size, payload_size);
+		return -EINVAL;
+	}
+
+	/* Walk the list of ISP configuration blocks and validate them. */
+	buffer_size = buffer->data_size;
+	while (buffer_size >= sizeof(struct v4l2_isp_params_block_header)) {
+		const struct v4l2_isp_params_block_info *block_info;
+		const struct v4l2_isp_params_block_header *block;
+
+		block = (const struct v4l2_isp_params_block_header *)
+			(buffer->data + block_offset);
+
+		if (block->type >= num_blocks) {
+			dev_dbg(dev,
+				"Invalid block type %u at offset %zu\n",
+				block->type, block_offset);
+			return -EINVAL;
+		}
+
+		if (block->size > buffer_size) {
+			dev_dbg(dev, "Premature end of parameters data\n");
+			return -EINVAL;
+		}
+
+		/* It's invalid to specify both ENABLE and DISABLE. */
+		if ((block->flags & (V4L2_ISP_PARAMS_FL_BLOCK_ENABLE |
+				     V4L2_ISP_PARAMS_FL_BLOCK_DISABLE)) ==
+		     (V4L2_ISP_PARAMS_FL_BLOCK_ENABLE |
+		     V4L2_ISP_PARAMS_FL_BLOCK_DISABLE)) {
+			dev_dbg(dev, "Invalid block flags %x at offset %zu\n",
+				block->flags, block_offset);
+			return -EINVAL;
+		}
+
+		/*
+		 * Match the block reported size against the info provided
+		 * one, but allow the block to only contain the header in
+		 * case it is going to be disabled.
+		 */
+		block_info = &info[block->type];
+		if (block->size != block_info->size &&
+		    (!(block->flags & V4L2_ISP_PARAMS_FL_BLOCK_DISABLE) ||
+		    block->size != sizeof(*block))) {
+			dev_dbg(dev,
+				"Invalid block size %u (expected %zu) at offset %zu\n",
+				block->size, block_info->size, block_offset);
+			return -EINVAL;
+		}
+
+		block_offset += block->size;
+		buffer_size -= block->size;
+	}
+
+	if (buffer_size) {
+		dev_dbg(dev, "Unexpected data after the parameters buffer end\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_isp_params_validate_buffer);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jacopo Mondi <jacopo.mondi@ideasonboard.com");
+MODULE_DESCRIPTION("V4L2 generic ISP parameters and statistics helpers");

include/media/v4l2-isp.h

@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Video4Linux2 generic ISP parameters and statistics support
+ *
+ * Copyright (C) 2025 Ideas On Board Oy
+ * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
+ */
+
+#ifndef _V4L2_ISP_H_
+#define _V4L2_ISP_H_
+
+#include <linux/media/v4l2-isp.h>
+
+struct device;
+struct vb2_buffer;
+
+/**
+ * v4l2_isp_params_buffer_size - Calculate size of v4l2_isp_params_buffer
+ * @max_params_size: The total size of the ISP configuration blocks
+ *
+ * Users of the v4l2 extensible parameters will have differing sized data arrays
+ * depending on their specific parameter buffers. Drivers and userspace will
+ * need to be able to calculate the appropriate size of the struct to
+ * accommodate all ISP configuration blocks provided by the platform.
+ * This macro provides a convenient tool for the calculation.
+ */
+#define v4l2_isp_params_buffer_size(max_params_size) \
+	(offsetof(struct v4l2_isp_params_buffer, data) + (max_params_size))
+
+/**
+ * v4l2_isp_params_validate_buffer_size - Validate a V4L2 ISP buffer sizes
+ * @dev: the driver's device pointer
+ * @vb: the videobuf2 buffer
+ * @max_size: the maximum allowed buffer size
+ *
+ * This function performs validation of the size of a V4L2 ISP parameters buffer
+ * before the driver can access the actual data buffer content.
+ *
+ * After the sizes validation, drivers should copy the buffer content to a
+ * kernel-only memory area to prevent userspace from modifying it,
+ * before completing validation using v4l2_isp_params_validate_buffer().
+ *
+ * The @vb buffer as received from the vb2 .buf_prepare() operation is checked
+ * against @max_size and it's validated to be large enough to accommodate at
+ * least one ISP configuration block.
+ */
+int v4l2_isp_params_validate_buffer_size(struct device *dev,
+					 struct vb2_buffer *vb,
+					 size_t max_size);
+
+/**
+ * struct v4l2_isp_params_block_info - V4L2 ISP per-block info
+ * @size: the block expected size
+ *
+ * The v4l2_isp_params_block_info collects information of the ISP configuration
+ * blocks for validation purposes. It currently only contains the expected
+ * block size.
+ *
+ * Drivers shall prepare a list of block info, indexed by block type, one for
+ * each supported ISP block and correctly populate them with the expected block
+ * size.
+ */
+struct v4l2_isp_params_block_info {
+	size_t size;
+};
+
+/**
+ * v4l2_isp_params_validate_buffer - Validate a V4L2 ISP parameters buffer
+ * @dev: the driver's device pointer
+ * @vb: the videobuf2 buffer
+ * @buffer: the V4L2 ISP parameters buffer
+ * @info: the list of per-block validation info
+ * @num_blocks: the number of blocks
+ *
+ * This function completes the validation of a V4L2 ISP parameters buffer,
+ * verifying each configuration block correctness before the driver can use
+ * them to program the hardware.
+ *
+ * Drivers should use this function after having validated the correctness of
+ * the vb2 buffer sizes by using the v4l2_isp_params_validate_buffer_size()
+ * helper first. Once the buffer size has been validated, drivers should
+ * perform a copy of the user provided buffer into a kernel-only memory buffer
+ * to prevent userspace from modifying its content after it has been submitted
+ * to the driver, and then call this function to complete validation.
+ */
+int v4l2_isp_params_validate_buffer(struct device *dev, struct vb2_buffer *vb,
+				    const struct v4l2_isp_params_buffer *buffer,
+				    const struct v4l2_isp_params_block_info *info,
+				    size_t num_blocks);
+
+#endif /* _V4L2_ISP_H_ */