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>

3 files changed, 137 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
index 331b8e535e5b..d50ccac9733c 100644
--- a/drivers/media/v4l2-core/Kconfig
+++ b/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
diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
index 2177b9d63a8f..329f0eadce99 100644
--- a/drivers/media/v4l2-core/Makefile
+++ b/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
diff --git a/drivers/media/v4l2-core/v4l2-isp.c b/drivers/media/v4l2-core/v4l2-isp.c
new file mode 100644
index 000000000000..756d2b4996cc
--- /dev/null
+++ b/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");