// SPDX-License-Identifier: GPL-2.0 /* * bsg.c - block layer implementation of the sg v4 interface */ #include <linux/module.h> #include <linux/init.h> #include <linux/file.h> #include <linux/blkdev.h> #include <linux/cdev.h> #include <linux/jiffies.h> #include <linux/percpu.h> #include <linux/idr.h> #include <linux/bsg.h> #include <linux/slab.h> #include <scsi/scsi.h> #include <scsi/scsi_ioctl.h> #include <scsi/scsi_cmnd.h> #include <scsi/scsi_device.h> #include <scsi/scsi_driver.h> #include <scsi/sg.h> #define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver" #define BSG_VERSION "0.4" #define bsg_dbg(bd, fmt, ...) \ pr_debug("%s: " fmt, (bd)->name, ##__VA_ARGS__) struct bsg_device { struct request_queue *queue; spinlock_t lock; struct hlist_node dev_list; refcount_t ref_count; char name[20]; int max_queue; }; #define BSG_DEFAULT_CMDS 64 #define BSG_MAX_DEVS 32768 static DEFINE_MUTEX(bsg_mutex); static DEFINE_IDR(bsg_minor_idr); #define BSG_LIST_ARRAY_SIZE 8 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE]; static struct class *bsg_class; static int bsg_major; static inline struct hlist_head *bsg_dev_idx_hash(int index) { return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)]; } #define uptr64(val) ((void __user *)(uintptr_t)(val)) static int bsg_scsi_check_proto(struct sg_io_v4 *hdr) { if (hdr->protocol != BSG_PROTOCOL_SCSI || hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD) return -EINVAL; return 0; } static int bsg_scsi_fill_hdr(struct request *rq, struct sg_io_v4 *hdr, fmode_t mode) { struct scsi_request *sreq = scsi_req(rq); if (hdr->dout_xfer_len && hdr->din_xfer_len) { pr_warn_once("BIDI support in bsg has been removed.\n"); return -EOPNOTSUPP; } sreq->cmd_len = hdr->request_len; if (sreq->cmd_len > BLK_MAX_CDB) { sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL); if (!sreq->cmd) return -ENOMEM; } if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len)) return -EFAULT; if (blk_verify_command(sreq->cmd, mode)) return -EPERM; return 0; } static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr) { struct scsi_request *sreq = scsi_req(rq); int ret = 0; /* * fill in all the output members */ hdr->device_status = sreq->result & 0xff; hdr->transport_status = host_byte(sreq->result); hdr->driver_status = driver_byte(sreq->result); hdr->info = 0; if (hdr->device_status || hdr->transport_status || hdr->driver_status) hdr->info |= SG_INFO_CHECK; hdr->response_len = 0; if (sreq->sense_len && hdr->response) { int len = min_t(unsigned int, hdr->max_response_len, sreq->sense_len); if (copy_to_user(uptr64(hdr->response), sreq->sense, len)) ret = -EFAULT; else hdr->response_len = len; } if (rq_data_dir(rq) == READ) hdr->din_resid = sreq->resid_len; else hdr->dout_resid = sreq->resid_len; return ret; } static void bsg_scsi_free_rq(struct request *rq) { scsi_req_free_cmd(scsi_req(rq)); } static const struct bsg_ops bsg_scsi_ops = { .check_proto = bsg_scsi_check_proto, .fill_hdr = bsg_scsi_fill_hdr, .complete_rq = bsg_scsi_complete_rq, .free_rq = bsg_scsi_free_rq, }; static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg) { struct request *rq; struct bio *bio; struct sg_io_v4 hdr; int ret; if (copy_from_user(&hdr, uarg, sizeof(hdr))) return -EFAULT; if (!q->bsg_dev.class_dev) return -ENXIO; if (hdr.guard != 'Q') return -EINVAL; ret = q->bsg_dev.ops->check_proto(&hdr); if (ret) return ret; rq = blk_get_request(q, hdr.dout_xfer_len ? REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0); if (IS_ERR(rq)) return PTR_ERR(rq); ret = q->bsg_dev.ops->fill_hdr(rq, &hdr, mode); if (ret) { blk_put_request(rq); return ret; } rq->timeout = msecs_to_jiffies(hdr.timeout); if (!rq->timeout) rq->timeout = q->sg_timeout; if (!rq->timeout) rq->timeout = BLK_DEFAULT_SG_TIMEOUT; if (rq->timeout < BLK_MIN_SG_TIMEOUT) rq->timeout = BLK_MIN_SG_TIMEOUT; if (hdr.dout_xfer_len) { ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.dout_xferp), hdr.dout_xfer_len, GFP_KERNEL); } else if (hdr.din_xfer_len) { ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.din_xferp), hdr.din_xfer_len, GFP_KERNEL); } if (ret) goto out_free_rq; bio = rq->bio; blk_execute_rq(NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL)); ret = rq->q->bsg_dev.ops->complete_rq(rq, &hdr); blk_rq_unmap_user(bio); out_free_rq: rq->q->bsg_dev.ops->free_rq(rq); blk_put_request(rq); if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr))) return -EFAULT; return ret; } static struct bsg_device *bsg_alloc_device(void) { struct bsg_device *bd; bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL); if (unlikely(!bd)) return NULL; spin_lock_init(&bd->lock); bd->max_queue = BSG_DEFAULT_CMDS; INIT_HLIST_NODE(&bd->dev_list); return bd; } static int bsg_put_device(struct bsg_device *bd) { struct request_queue *q = bd->queue; mutex_lock(&bsg_mutex); if (!refcount_dec_and_test(&bd->ref_count)) { mutex_unlock(&bsg_mutex); return 0; } hlist_del(&bd->dev_list); mutex_unlock(&bsg_mutex); bsg_dbg(bd, "tearing down\n"); /* * close can always block */ kfree(bd); blk_put_queue(q); return 0; } static struct bsg_device *bsg_add_device(struct inode *inode, struct request_queue *rq, struct file *file) { struct bsg_device *bd; unsigned char buf[32]; lockdep_assert_held(&bsg_mutex); if (!blk_get_queue(rq)) return ERR_PTR(-ENXIO); bd = bsg_alloc_device(); if (!bd) { blk_put_queue(rq); return ERR_PTR(-ENOMEM); } bd->queue = rq; refcount_set(&bd->ref_count, 1); hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode))); strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1); bsg_dbg(bd, "bound to <%s>, max queue %d\n", format_dev_t(buf, inode->i_rdev), bd->max_queue); return bd; } static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q) { struct bsg_device *bd; lockdep_assert_held(&bsg_mutex); hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) { if (bd->queue == q) { refcount_inc(&bd->ref_count); goto found; } } bd = NULL; found: return bd; } static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file) { struct bsg_device *bd; struct bsg_class_device *bcd; /* * find the class device */ mutex_lock(&bsg_mutex); bcd = idr_find(&bsg_minor_idr, iminor(inode)); if (!bcd) { bd = ERR_PTR(-ENODEV); goto out_unlock; } bd = __bsg_get_device(iminor(inode), bcd->queue); if (!bd) bd = bsg_add_device(inode, bcd->queue, file); out_unlock: mutex_unlock(&bsg_mutex); return bd; } static int bsg_open(struct inode *inode, struct file *file) { struct bsg_device *bd; bd = bsg_get_device(inode, file); if (IS_ERR(bd)) return PTR_ERR(bd); file->private_data = bd; return 0; } static int bsg_release(struct inode *inode, struct file *file) { struct bsg_device *bd = file->private_data; file->private_data = NULL; return bsg_put_device(bd); } static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg) { return put_user(bd->max_queue, uarg); } static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg) { int queue; if (get_user(queue, uarg)) return -EFAULT; if (queue < 1) return -EINVAL; spin_lock_irq(&bd->lock); bd->max_queue = queue; spin_unlock_irq(&bd->lock); return 0; } static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct bsg_device *bd = file->private_data; void __user *uarg = (void __user *) arg; switch (cmd) { /* * Our own ioctls */ case SG_GET_COMMAND_Q: return bsg_get_command_q(bd, uarg); case SG_SET_COMMAND_Q: return bsg_set_command_q(bd, uarg); /* * SCSI/sg ioctls */ case SG_GET_VERSION_NUM: case SCSI_IOCTL_GET_IDLUN: case SCSI_IOCTL_GET_BUS_NUMBER: case SG_SET_TIMEOUT: case SG_GET_TIMEOUT: case SG_GET_RESERVED_SIZE: case SG_SET_RESERVED_SIZE: case SG_EMULATED_HOST: case SCSI_IOCTL_SEND_COMMAND: return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg); case SG_IO: return bsg_sg_io(bd->queue, file->f_mode, uarg); default: return -ENOTTY; } } static const struct file_operations bsg_fops = { .open = bsg_open, .release = bsg_release, .unlocked_ioctl = bsg_ioctl, .compat_ioctl = compat_ptr_ioctl, .owner = THIS_MODULE, .llseek = default_llseek, }; void bsg_unregister_queue(struct request_queue *q) { struct bsg_class_device *bcd = &q->bsg_dev; if (!bcd->class_dev) return; mutex_lock(&bsg_mutex); idr_remove(&bsg_minor_idr, bcd->minor); if (q->kobj.sd) sysfs_remove_link(&q->kobj, "bsg"); device_unregister(bcd->class_dev); bcd->class_dev = NULL; mutex_unlock(&bsg_mutex); } EXPORT_SYMBOL_GPL(bsg_unregister_queue); int bsg_register_queue(struct request_queue *q, struct device *parent, const char *name, const struct bsg_ops *ops) { struct bsg_class_device *bcd; dev_t dev; int ret; struct device *class_dev = NULL; /* * we need a proper transport to send commands, not a stacked device */ if (!queue_is_mq(q)) return 0; bcd = &q->bsg_dev; memset(bcd, 0, sizeof(*bcd)); mutex_lock(&bsg_mutex); ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL); if (ret < 0) { if (ret == -ENOSPC) { printk(KERN_ERR "bsg: too many bsg devices\n"); ret = -EINVAL; } goto unlock; } bcd->minor = ret; bcd->queue = q; bcd->ops = ops; dev = MKDEV(bsg_major, bcd->minor); class_dev = device_create(bsg_class, parent, dev, NULL, "%s", name); if (IS_ERR(class_dev)) { ret = PTR_ERR(class_dev); goto idr_remove; } bcd->class_dev = class_dev; if (q->kobj.sd) { ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg"); if (ret) goto unregister_class_dev; } mutex_unlock(&bsg_mutex); return 0; unregister_class_dev: device_unregister(class_dev); idr_remove: idr_remove(&bsg_minor_idr, bcd->minor); unlock: mutex_unlock(&bsg_mutex); return ret; } int bsg_scsi_register_queue(struct request_queue *q, struct device *parent) { if (!blk_queue_scsi_passthrough(q)) { WARN_ONCE(true, "Attempt to register a non-SCSI queue\n"); return -EINVAL; } return bsg_register_queue(q, parent, dev_name(parent), &bsg_scsi_ops); } EXPORT_SYMBOL_GPL(bsg_scsi_register_queue); static struct cdev bsg_cdev; static char *bsg_devnode(struct device *dev, umode_t *mode) { return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev)); } static int __init bsg_init(void) { int ret, i; dev_t devid; for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++) INIT_HLIST_HEAD(&bsg_device_list[i]); bsg_class = class_create(THIS_MODULE, "bsg"); if (IS_ERR(bsg_class)) return PTR_ERR(bsg_class); bsg_class->devnode = bsg_devnode; ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg"); if (ret) goto destroy_bsg_class; bsg_major = MAJOR(devid); cdev_init(&bsg_cdev, &bsg_fops); ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS); if (ret) goto unregister_chrdev; printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION " loaded (major %d)\n", bsg_major); return 0; unregister_chrdev: unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS); destroy_bsg_class: class_destroy(bsg_class); return ret; } MODULE_AUTHOR("Jens Axboe"); MODULE_DESCRIPTION(BSG_DESCRIPTION); MODULE_LICENSE("GPL"); device_initcall(bsg_init);