1 files changed, 277 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_bsg.c b/drivers/scsi/scsi_bsg.c
new file mode 100644
index 000000000..e80dec531
--- /dev/null
+++ b/drivers/scsi/scsi_bsg.c
@@ -0,0 +1,277 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bsg.h>
+#include <linux/io_uring/cmd.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_device.h>
+#include <scsi/sg.h>
+#include "scsi_priv.h"
+
+#define uptr64(val) ((void __user *)(uintptr_t)(val))
+
+/*
+ * Per-command BSG SCSI PDU stored in io_uring_cmd.pdu[32].
+ * Holds temporary state between submission, completion and task_work.
+ */
+struct scsi_bsg_uring_cmd_pdu {
+	struct bio *bio;		/* mapped user buffer, unmap in task work */
+	struct request *req;		/* block request, freed in task work */
+	u64 response_addr;		/* user space response buffer address */
+};
+static_assert(sizeof(struct scsi_bsg_uring_cmd_pdu) <= sizeof_field(struct io_uring_cmd, pdu));
+
+static inline struct scsi_bsg_uring_cmd_pdu *scsi_bsg_uring_cmd_pdu(
+	struct io_uring_cmd *ioucmd)
+{
+	return io_uring_cmd_to_pdu(ioucmd, struct scsi_bsg_uring_cmd_pdu);
+}
+
+/* Task work: build res2 (layout in uapi/linux/bsg.h) and copy sense to user. */
+static void scsi_bsg_uring_task_cb(struct io_tw_req tw_req, io_tw_token_t tw)
+{
+	struct io_uring_cmd *ioucmd = io_uring_cmd_from_tw(tw_req);
+	struct scsi_bsg_uring_cmd_pdu *pdu = scsi_bsg_uring_cmd_pdu(ioucmd);
+	struct request *rq = pdu->req;
+	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
+	u64 res2;
+	int ret = 0;
+	u8 driver_status = 0;
+	u8 sense_len_wr = 0;
+
+	if (pdu->bio)
+		blk_rq_unmap_user(pdu->bio);
+
+	if (scsi_status_is_check_condition(scmd->result)) {
+		driver_status = DRIVER_SENSE;
+		if (pdu->response_addr)
+			sense_len_wr = min_t(u8, scmd->sense_len,
+					     SCSI_SENSE_BUFFERSIZE);
+	}
+
+	if (sense_len_wr) {
+		if (copy_to_user(uptr64(pdu->response_addr), scmd->sense_buffer,
+				 sense_len_wr))
+			ret = -EFAULT;
+	}
+
+	res2 = bsg_scsi_res2_build(status_byte(scmd->result), driver_status,
+				  host_byte(scmd->result), sense_len_wr,
+				  scmd->resid_len);
+
+	blk_mq_free_request(rq);
+	io_uring_cmd_done32(ioucmd, ret, res2,
+			    IO_URING_CMD_TASK_WORK_ISSUE_FLAGS);
+}
+
+static enum rq_end_io_ret scsi_bsg_uring_cmd_done(struct request *req,
+						  blk_status_t status,
+						  const struct io_comp_batch *iocb)
+{
+	struct io_uring_cmd *ioucmd = req->end_io_data;
+
+	io_uring_cmd_do_in_task_lazy(ioucmd, scsi_bsg_uring_task_cb);
+	return RQ_END_IO_NONE;
+}
+
+static int scsi_bsg_map_user_buffer(struct request *req,
+				    struct io_uring_cmd *ioucmd,
+				    unsigned int issue_flags, gfp_t gfp_mask)
+{
+	const struct bsg_uring_cmd *cmd = io_uring_sqe128_cmd(ioucmd->sqe, struct bsg_uring_cmd);
+	bool is_write = cmd->dout_xfer_len > 0;
+	u64 buf_addr = is_write ? cmd->dout_xferp : cmd->din_xferp;
+	unsigned long buf_len = is_write ? cmd->dout_xfer_len : cmd->din_xfer_len;
+	struct iov_iter iter;
+	int ret;
+
+	if (ioucmd->flags & IORING_URING_CMD_FIXED) {
+		ret = io_uring_cmd_import_fixed(buf_addr, buf_len,
+						is_write ? WRITE : READ,
+						&iter, ioucmd, issue_flags);
+		if (ret < 0)
+			return ret;
+		ret = blk_rq_map_user_iov(req->q, req, NULL, &iter, gfp_mask);
+	} else {
+		ret = blk_rq_map_user(req->q, req, NULL, uptr64(buf_addr),
+				      buf_len, gfp_mask);
+	}
+
+	return ret;
+}
+
+static int scsi_bsg_uring_cmd(struct request_queue *q, struct io_uring_cmd *ioucmd,
+			       unsigned int issue_flags, bool open_for_write)
+{
+	struct scsi_bsg_uring_cmd_pdu *pdu = scsi_bsg_uring_cmd_pdu(ioucmd);
+	const struct bsg_uring_cmd *cmd = io_uring_sqe128_cmd(ioucmd->sqe, struct bsg_uring_cmd);
+	struct scsi_cmnd *scmd;
+	struct request *req;
+	blk_mq_req_flags_t blk_flags = 0;
+	gfp_t gfp_mask = GFP_KERNEL;
+	int ret;
+
+	if (cmd->protocol != BSG_PROTOCOL_SCSI ||
+	    cmd->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
+		return -EINVAL;
+
+	if (!cmd->request || cmd->request_len == 0)
+		return -EINVAL;
+
+	if (cmd->dout_xfer_len && cmd->din_xfer_len) {
+		pr_warn_once("BIDI support in bsg has been removed.\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (cmd->dout_iovec_count > 0 || cmd->din_iovec_count > 0)
+		return -EOPNOTSUPP;
+
+	if (issue_flags & IO_URING_F_NONBLOCK) {
+		blk_flags = BLK_MQ_REQ_NOWAIT;
+		gfp_mask = GFP_NOWAIT;
+	}
+
+	req = scsi_alloc_request(q, cmd->dout_xfer_len ?
+				 REQ_OP_DRV_OUT : REQ_OP_DRV_IN, blk_flags);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	scmd = blk_mq_rq_to_pdu(req);
+	if (cmd->request_len > sizeof(scmd->cmnd)) {
+		ret = -EINVAL;
+		goto out_free_req;
+	}
+	scmd->cmd_len = cmd->request_len;
+	scmd->allowed = SG_DEFAULT_RETRIES;
+
+	if (copy_from_user(scmd->cmnd, uptr64(cmd->request), cmd->request_len)) {
+		ret = -EFAULT;
+		goto out_free_req;
+	}
+
+	if (!scsi_cmd_allowed(scmd->cmnd, open_for_write)) {
+		ret = -EPERM;
+		goto out_free_req;
+	}
+
+	pdu->response_addr = cmd->response;
+	scmd->sense_len = cmd->max_response_len ?
+		min(cmd->max_response_len, SCSI_SENSE_BUFFERSIZE) : SCSI_SENSE_BUFFERSIZE;
+
+	if (cmd->dout_xfer_len || cmd->din_xfer_len) {
+		ret = scsi_bsg_map_user_buffer(req, ioucmd, issue_flags, gfp_mask);
+		if (ret)
+			goto out_free_req;
+		pdu->bio = req->bio;
+	} else {
+		pdu->bio = NULL;
+	}
+
+	req->timeout = cmd->timeout_ms ?
+		msecs_to_jiffies(cmd->timeout_ms) : BLK_DEFAULT_SG_TIMEOUT;
+
+	req->end_io = scsi_bsg_uring_cmd_done;
+	req->end_io_data = ioucmd;
+	pdu->req = req;
+
+	blk_execute_rq_nowait(req, false);
+	return -EIOCBQUEUED;
+
+out_free_req:
+	blk_mq_free_request(req);
+	return ret;
+}
+
+static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
+		bool open_for_write, unsigned int timeout)
+{
+	struct scsi_cmnd *scmd;
+	struct request *rq;
+	struct bio *bio;
+	int ret;
+
+	if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
+	    hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
+		return -EINVAL;
+	if (hdr->dout_xfer_len && hdr->din_xfer_len) {
+		pr_warn_once("BIDI support in bsg has been removed.\n");
+		return -EOPNOTSUPP;
+	}
+
+	rq = scsi_alloc_request(q, hdr->dout_xfer_len ?
+				REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
+	if (IS_ERR(rq))
+		return PTR_ERR(rq);
+	rq->timeout = timeout;
+
+	scmd = blk_mq_rq_to_pdu(rq);
+	scmd->cmd_len = hdr->request_len;
+	if (scmd->cmd_len > sizeof(scmd->cmnd)) {
+		ret = -EINVAL;
+		goto out_put_request;
+	}
+
+	ret = -EFAULT;
+	if (copy_from_user(scmd->cmnd, uptr64(hdr->request), scmd->cmd_len))
+		goto out_put_request;
+	ret = -EPERM;
+	if (!scsi_cmd_allowed(scmd->cmnd, open_for_write))
+		goto out_put_request;
+
+	ret = 0;
+	if (hdr->dout_xfer_len) {
+		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->dout_xferp),
+				hdr->dout_xfer_len, GFP_KERNEL);
+	} else if (hdr->din_xfer_len) {
+		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->din_xferp),
+				hdr->din_xfer_len, GFP_KERNEL);
+	}
+
+	if (ret)
+		goto out_put_request;
+
+	bio = rq->bio;
+	blk_execute_rq(rq, !(hdr->flags & BSG_FLAG_Q_AT_TAIL));
+
+	/*
+	 * fill in all the output members
+	 */
+	hdr->device_status = scmd->result & 0xff;
+	hdr->transport_status = host_byte(scmd->result);
+	hdr->driver_status = 0;
+	if (scsi_status_is_check_condition(scmd->result))
+		hdr->driver_status = DRIVER_SENSE;
+	hdr->info = 0;
+	if (hdr->device_status || hdr->transport_status || hdr->driver_status)
+		hdr->info |= SG_INFO_CHECK;
+	hdr->response_len = 0;
+
+	if (scmd->sense_len && hdr->response) {
+		int len = min_t(unsigned int, hdr->max_response_len,
+				scmd->sense_len);
+
+		if (copy_to_user(uptr64(hdr->response), scmd->sense_buffer,
+				 len))
+			ret = -EFAULT;
+		else
+			hdr->response_len = len;
+	}
+
+	if (rq_data_dir(rq) == READ)
+		hdr->din_resid = scmd->resid_len;
+	else
+		hdr->dout_resid = scmd->resid_len;
+
+	blk_rq_unmap_user(bio);
+
+out_put_request:
+	blk_mq_free_request(rq);
+	return ret;
+}
+
+struct bsg_device *scsi_bsg_register_queue(struct scsi_device *sdev)
+{
+	return bsg_register_queue(sdev->request_queue, &sdev->sdev_gendev,
+			dev_name(&sdev->sdev_gendev), scsi_bsg_sg_io_fn,
+			scsi_bsg_uring_cmd);
+}