// 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/sg.h> #define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver" #define BSG_VERSION "0.4" struct bsg_device { struct request_queue *queue; struct device device; struct cdev cdev; int max_queue; unsigned int timeout; unsigned int reserved_size; bsg_sg_io_fn *sg_io_fn; }; static inline struct bsg_device *to_bsg_device(struct inode *inode) { return container_of(inode->i_cdev, struct bsg_device, cdev); } #define BSG_DEFAULT_CMDS 64 #define BSG_MAX_DEVS (1 << MINORBITS) static DEFINE_IDA(bsg_minor_ida); static const struct class bsg_class; static int bsg_major; static unsigned int bsg_timeout(struct bsg_device *bd, struct sg_io_v4 *hdr) { unsigned int timeout = BLK_DEFAULT_SG_TIMEOUT; if (hdr->timeout) timeout = msecs_to_jiffies(hdr->timeout); else if (bd->timeout) timeout = bd->timeout; return max_t(unsigned int, timeout, BLK_MIN_SG_TIMEOUT); } static int bsg_sg_io(struct bsg_device *bd, bool open_for_write, void __user *uarg) { struct sg_io_v4 hdr; int ret; if (copy_from_user(&hdr, uarg, sizeof(hdr))) return -EFAULT; if (hdr.guard != 'Q') return -EINVAL; ret = bd->sg_io_fn(bd->queue, &hdr, open_for_write, bsg_timeout(bd, &hdr)); if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr))) return -EFAULT; return ret; } static int bsg_open(struct inode *inode, struct file *file) { if (!blk_get_queue(to_bsg_device(inode)->queue)) return -ENXIO; return 0; } static int bsg_release(struct inode *inode, struct file *file) { blk_put_queue(to_bsg_device(inode)->queue); return 0; } static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg) { return put_user(READ_ONCE(bd->max_queue), uarg); } static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg) { int max_queue; if (get_user(max_queue, uarg)) return -EFAULT; if (max_queue < 1) return -EINVAL; WRITE_ONCE(bd->max_queue, max_queue); return 0; } static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct bsg_device *bd = to_bsg_device(file_inode(file)); struct request_queue *q = bd->queue; void __user *uarg = (void __user *) arg; int __user *intp = uarg; int val; 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: return put_user(30527, intp); case SCSI_IOCTL_GET_IDLUN: return put_user(0, intp); case SCSI_IOCTL_GET_BUS_NUMBER: return put_user(0, intp); case SG_SET_TIMEOUT: if (get_user(val, intp)) return -EFAULT; bd->timeout = clock_t_to_jiffies(val); return 0; case SG_GET_TIMEOUT: return jiffies_to_clock_t(bd->timeout); case SG_GET_RESERVED_SIZE: return put_user(min(bd->reserved_size, queue_max_bytes(q)), intp); case SG_SET_RESERVED_SIZE: if (get_user(val, intp)) return -EFAULT; if (val < 0) return -EINVAL; bd->reserved_size = min_t(unsigned int, val, queue_max_bytes(q)); return 0; case SG_EMULATED_HOST: return put_user(1, intp); case SG_IO: return bsg_sg_io(bd, file->f_mode & FMODE_WRITE, uarg); case SCSI_IOCTL_SEND_COMMAND: pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n", current->comm); return -EINVAL; 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, }; static void bsg_device_release(struct device *dev) { struct bsg_device *bd = container_of(dev, struct bsg_device, device); ida_free(&bsg_minor_ida, MINOR(bd->device.devt)); kfree(bd); } void bsg_unregister_queue(struct bsg_device *bd) { struct gendisk *disk = bd->queue->disk; if (disk && disk->queue_kobj.sd) sysfs_remove_link(&disk->queue_kobj, "bsg"); cdev_device_del(&bd->cdev, &bd->device); put_device(&bd->device); } EXPORT_SYMBOL_GPL(bsg_unregister_queue); struct bsg_device *bsg_register_queue(struct request_queue *q, struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn) { struct bsg_device *bd; int ret; bd = kzalloc(sizeof(*bd), GFP_KERNEL); if (!bd) return ERR_PTR(-ENOMEM); bd->max_queue = BSG_DEFAULT_CMDS; bd->reserved_size = INT_MAX; bd->queue = q; bd->sg_io_fn = sg_io_fn; ret = ida_alloc_max(&bsg_minor_ida, BSG_MAX_DEVS - 1, GFP_KERNEL); if (ret < 0) { if (ret == -ENOSPC) dev_err(parent, "bsg: too many bsg devices\n"); kfree(bd); return ERR_PTR(ret); } bd->device.devt = MKDEV(bsg_major, ret); bd->device.class = &bsg_class; bd->device.parent = parent; bd->device.release = bsg_device_release; dev_set_name(&bd->device, "%s", name); device_initialize(&bd->device); cdev_init(&bd->cdev, &bsg_fops); bd->cdev.owner = THIS_MODULE; ret = cdev_device_add(&bd->cdev, &bd->device); if (ret) goto out_put_device; if (q->disk && q->disk->queue_kobj.sd) { ret = sysfs_create_link(&q->disk->queue_kobj, &bd->device.kobj, "bsg"); if (ret) goto out_device_del; } return bd; out_device_del: cdev_device_del(&bd->cdev, &bd->device); out_put_device: put_device(&bd->device); return ERR_PTR(ret); } EXPORT_SYMBOL_GPL(bsg_register_queue); static char *bsg_devnode(const struct device *dev, umode_t *mode) { return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev)); } static const struct class bsg_class = { .name = "bsg", .devnode = bsg_devnode, }; static int __init bsg_init(void) { dev_t devid; int ret; ret = class_register(&bsg_class); if (ret) return ret; ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg"); if (ret) goto destroy_bsg_class; bsg_major = MAJOR(devid); printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION " loaded (major %d)\n", bsg_major); return 0; destroy_bsg_class: class_unregister(&bsg_class); return ret; } MODULE_AUTHOR("Jens Axboe"); MODULE_DESCRIPTION(BSG_DESCRIPTION); MODULE_LICENSE("GPL"); device_initcall(bsg_init);