block/bsg.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * bsg.c - block layer implementation of the sg v4 interface
   4  */
   5 #include <linux/module.h>
   6 #include <linux/init.h>
   7 #include <linux/file.h>
   8 #include <linux/blkdev.h>
   9 #include <linux/cdev.h>
  10 #include <linux/jiffies.h>
  11 #include <linux/percpu.h>
  12 #include <linux/idr.h>
  13 #include <linux/bsg.h>
  14 #include <linux/slab.h>
  15
  16 #include <scsi/scsi.h>
  17 #include <scsi/scsi_ioctl.h>
  18 #include <scsi/sg.h>
  19
  20 #define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
  21 #define BSG_VERSION     "0.4"
  22
  23 struct bsg_device {
  24         struct request_queue *queue;
  25         struct device device;
  26         struct cdev cdev;
  27         int max_queue;
  28         unsigned int timeout;
  29         unsigned int reserved_size;
  30         bsg_sg_io_fn *sg_io_fn;
  31 };
  32
  33 static inline struct bsg_device *to_bsg_device(struct inode *inode)
  34 {
  35         return container_of(inode->i_cdev, struct bsg_device, cdev);
  36 }
  37
  38 #define BSG_DEFAULT_CMDS        64
  39 #define BSG_MAX_DEVS            (1 << MINORBITS)
  40
  41 static DEFINE_IDA(bsg_minor_ida);
  42 static const struct class bsg_class;
  43 static int bsg_major;
  44
  45 static unsigned int bsg_timeout(struct bsg_device *bd, struct sg_io_v4 *hdr)
  46 {
  47         unsigned int timeout = BLK_DEFAULT_SG_TIMEOUT;
  48
  49         if (hdr->timeout)
  50                 timeout = msecs_to_jiffies(hdr->timeout);
  51         else if (bd->timeout)
  52                 timeout = bd->timeout;
  53
  54         return max_t(unsigned int, timeout, BLK_MIN_SG_TIMEOUT);
  55 }
  56
  57 static int bsg_sg_io(struct bsg_device *bd, bool open_for_write,
  58                      void __user *uarg)
  59 {
  60         struct sg_io_v4 hdr;
  61         int ret;
  62
  63         if (copy_from_user(&hdr, uarg, sizeof(hdr)))
  64                 return -EFAULT;
  65         if (hdr.guard != 'Q')
  66                 return -EINVAL;
  67         ret = bd->sg_io_fn(bd->queue, &hdr, open_for_write,
  68                            bsg_timeout(bd, &hdr));
  69         if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
  70                 return -EFAULT;
  71         return ret;
  72 }
  73
  74 static int bsg_open(struct inode *inode, struct file *file)
  75 {
  76         if (!blk_get_queue(to_bsg_device(inode)->queue))
  77                 return -ENXIO;
  78         return 0;
  79 }
  80
  81 static int bsg_release(struct inode *inode, struct file *file)
  82 {
  83         blk_put_queue(to_bsg_device(inode)->queue);
  84         return 0;
  85 }
  86
  87 static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
  88 {
  89         return put_user(READ_ONCE(bd->max_queue), uarg);
  90 }
  91
  92 static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
  93 {
  94         int max_queue;
  95
  96         if (get_user(max_queue, uarg))
  97                 return -EFAULT;
  98         if (max_queue < 1)
  99                 return -EINVAL;
 100         WRITE_ONCE(bd->max_queue, max_queue);
 101         return 0;
 102 }
 103
 104 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 105 {
 106         struct bsg_device *bd = to_bsg_device(file_inode(file));
 107         struct request_queue *q = bd->queue;
 108         void __user *uarg = (void __user *) arg;
 109         int __user *intp = uarg;
 110         int val;
 111
 112         switch (cmd) {
 113         /*
 114          * Our own ioctls
 115          */
 116         case SG_GET_COMMAND_Q:
 117                 return bsg_get_command_q(bd, uarg);
 118         case SG_SET_COMMAND_Q:
 119                 return bsg_set_command_q(bd, uarg);
 120
 121         /*
 122          * SCSI/sg ioctls
 123          */
 124         case SG_GET_VERSION_NUM:
 125                 return put_user(30527, intp);
 126         case SCSI_IOCTL_GET_IDLUN:
 127                 return put_user(0, intp);
 128         case SCSI_IOCTL_GET_BUS_NUMBER:
 129                 return put_user(0, intp);
 130         case SG_SET_TIMEOUT:
 131                 if (get_user(val, intp))
 132                         return -EFAULT;
 133                 bd->timeout = clock_t_to_jiffies(val);
 134                 return 0;
 135         case SG_GET_TIMEOUT:
 136                 return jiffies_to_clock_t(bd->timeout);
 137         case SG_GET_RESERVED_SIZE:
 138                 return put_user(min(bd->reserved_size, queue_max_bytes(q)),
 139                                 intp);
 140         case SG_SET_RESERVED_SIZE:
 141                 if (get_user(val, intp))
 142                         return -EFAULT;
 143                 if (val < 0)
 144                         return -EINVAL;
 145                 bd->reserved_size =
 146                         min_t(unsigned int, val, queue_max_bytes(q));
 147                 return 0;
 148         case SG_EMULATED_HOST:
 149                 return put_user(1, intp);
 150         case SG_IO:
 151                 return bsg_sg_io(bd, file->f_mode & FMODE_WRITE, uarg);
 152         case SCSI_IOCTL_SEND_COMMAND:
 153                 pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n",
 154                                 current->comm);
 155                 return -EINVAL;
 156         default:
 157                 return -ENOTTY;
 158         }
 159 }
 160
 161 static const struct file_operations bsg_fops = {
 162         .open           =       bsg_open,
 163         .release        =       bsg_release,
 164         .unlocked_ioctl =       bsg_ioctl,
 165         .compat_ioctl   =       compat_ptr_ioctl,
 166         .owner          =       THIS_MODULE,
 167         .llseek         =       default_llseek,
 168 };
 169
 170 static void bsg_device_release(struct device *dev)
 171 {
 172         struct bsg_device *bd = container_of(dev, struct bsg_device, device);
 173
 174         ida_free(&bsg_minor_ida, MINOR(bd->device.devt));
 175         kfree(bd);
 176 }
 177
 178 void bsg_unregister_queue(struct bsg_device *bd)
 179 {
 180         struct gendisk *disk = bd->queue->disk;
 181
 182         if (disk && disk->queue_kobj.sd)
 183                 sysfs_remove_link(&disk->queue_kobj, "bsg");
 184         cdev_device_del(&bd->cdev, &bd->device);
 185         put_device(&bd->device);
 186 }
 187 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 188
 189 struct bsg_device *bsg_register_queue(struct request_queue *q,
 190                 struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn)
 191 {
 192         struct bsg_device *bd;
 193         int ret;
 194
 195         bd = kzalloc(sizeof(*bd), GFP_KERNEL);
 196         if (!bd)
 197                 return ERR_PTR(-ENOMEM);
 198         bd->max_queue = BSG_DEFAULT_CMDS;
 199         bd->reserved_size = INT_MAX;
 200         bd->queue = q;
 201         bd->sg_io_fn = sg_io_fn;
 202
 203         ret = ida_alloc_max(&bsg_minor_ida, BSG_MAX_DEVS - 1, GFP_KERNEL);
 204         if (ret < 0) {
 205                 if (ret == -ENOSPC)
 206                         dev_err(parent, "bsg: too many bsg devices\n");
 207                 kfree(bd);
 208                 return ERR_PTR(ret);
 209         }
 210         bd->device.devt = MKDEV(bsg_major, ret);
 211         bd->device.class = &bsg_class;
 212         bd->device.parent = parent;
 213         bd->device.release = bsg_device_release;
 214         dev_set_name(&bd->device, "%s", name);
 215         device_initialize(&bd->device);
 216
 217         cdev_init(&bd->cdev, &bsg_fops);
 218         bd->cdev.owner = THIS_MODULE;
 219         ret = cdev_device_add(&bd->cdev, &bd->device);
 220         if (ret)
 221                 goto out_put_device;
 222
 223         if (q->disk && q->disk->queue_kobj.sd) {
 224                 ret = sysfs_create_link(&q->disk->queue_kobj, &bd->device.kobj,
 225                                         "bsg");
 226                 if (ret)
 227                         goto out_device_del;
 228         }
 229
 230         return bd;
 231
 232 out_device_del:
 233         cdev_device_del(&bd->cdev, &bd->device);
 234 out_put_device:
 235         put_device(&bd->device);
 236         return ERR_PTR(ret);
 237 }
 238 EXPORT_SYMBOL_GPL(bsg_register_queue);
 239
 240 static char *bsg_devnode(const struct device *dev, umode_t *mode)
 241 {
 242         return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
 243 }
 244
 245 static const struct class bsg_class = {
 246         .name           = "bsg",
 247         .devnode        = bsg_devnode,
 248 };
 249
 250 static int __init bsg_init(void)
 251 {
 252         dev_t devid;
 253         int ret;
 254
 255         ret = class_register(&bsg_class);
 256         if (ret)
 257                 return ret;
 258
 259         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
 260         if (ret)
 261                 goto destroy_bsg_class;
 262         bsg_major = MAJOR(devid);
 263
 264         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
 265                " loaded (major %d)\n", bsg_major);
 266         return 0;
 267
 268 destroy_bsg_class:
 269         class_unregister(&bsg_class);
 270         return ret;
 271 }
 272
 273 MODULE_AUTHOR("Jens Axboe");
 274 MODULE_DESCRIPTION(BSG_DESCRIPTION);
 275 MODULE_LICENSE("GPL");
 276
 277 device_initcall(bsg_init);