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 32768 40 41 static DEFINE_IDA(bsg_minor_ida); 42 static 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, fmode_t mode, void __user *uarg) 58 { 59 struct sg_io_v4 hdr; 60 int ret; 61 62 if (copy_from_user(&hdr, uarg, sizeof(hdr))) 63 return -EFAULT; 64 if (hdr.guard != 'Q') 65 return -EINVAL; 66 ret = bd->sg_io_fn(bd->queue, &hdr, mode, bsg_timeout(bd, &hdr)); 67 if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr))) 68 return -EFAULT; 69 return ret; 70 } 71 72 static int bsg_open(struct inode *inode, struct file *file) 73 { 74 if (!blk_get_queue(to_bsg_device(inode)->queue)) 75 return -ENXIO; 76 return 0; 77 } 78 79 static int bsg_release(struct inode *inode, struct file *file) 80 { 81 blk_put_queue(to_bsg_device(inode)->queue); 82 return 0; 83 } 84 85 static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg) 86 { 87 return put_user(READ_ONCE(bd->max_queue), uarg); 88 } 89 90 static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg) 91 { 92 int max_queue; 93 94 if (get_user(max_queue, uarg)) 95 return -EFAULT; 96 if (max_queue < 1) 97 return -EINVAL; 98 WRITE_ONCE(bd->max_queue, max_queue); 99 return 0; 100 } 101 102 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 103 { 104 struct bsg_device *bd = to_bsg_device(file_inode(file)); 105 struct request_queue *q = bd->queue; 106 void __user *uarg = (void __user *) arg; 107 int __user *intp = uarg; 108 int val; 109 110 switch (cmd) { 111 /* 112 * Our own ioctls 113 */ 114 case SG_GET_COMMAND_Q: 115 return bsg_get_command_q(bd, uarg); 116 case SG_SET_COMMAND_Q: 117 return bsg_set_command_q(bd, uarg); 118 119 /* 120 * SCSI/sg ioctls 121 */ 122 case SG_GET_VERSION_NUM: 123 return put_user(30527, intp); 124 case SCSI_IOCTL_GET_IDLUN: 125 return put_user(0, intp); 126 case SCSI_IOCTL_GET_BUS_NUMBER: 127 return put_user(0, intp); 128 case SG_SET_TIMEOUT: 129 if (get_user(val, intp)) 130 return -EFAULT; 131 bd->timeout = clock_t_to_jiffies(val); 132 return 0; 133 case SG_GET_TIMEOUT: 134 return jiffies_to_clock_t(bd->timeout); 135 case SG_GET_RESERVED_SIZE: 136 return put_user(min(bd->reserved_size, queue_max_bytes(q)), 137 intp); 138 case SG_SET_RESERVED_SIZE: 139 if (get_user(val, intp)) 140 return -EFAULT; 141 if (val < 0) 142 return -EINVAL; 143 bd->reserved_size = 144 min_t(unsigned int, val, queue_max_bytes(q)); 145 return 0; 146 case SG_EMULATED_HOST: 147 return put_user(1, intp); 148 case SG_IO: 149 return bsg_sg_io(bd, file->f_mode, uarg); 150 case SCSI_IOCTL_SEND_COMMAND: 151 pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n", 152 current->comm); 153 return -EINVAL; 154 default: 155 return -ENOTTY; 156 } 157 } 158 159 static const struct file_operations bsg_fops = { 160 .open = bsg_open, 161 .release = bsg_release, 162 .unlocked_ioctl = bsg_ioctl, 163 .compat_ioctl = compat_ptr_ioctl, 164 .owner = THIS_MODULE, 165 .llseek = default_llseek, 166 }; 167 168 static void bsg_device_release(struct device *dev) 169 { 170 struct bsg_device *bd = container_of(dev, struct bsg_device, device); 171 172 ida_free(&bsg_minor_ida, MINOR(bd->device.devt)); 173 kfree(bd); 174 } 175 176 void bsg_unregister_queue(struct bsg_device *bd) 177 { 178 struct gendisk *disk = bd->queue->disk; 179 180 if (disk && disk->queue_kobj.sd) 181 sysfs_remove_link(&disk->queue_kobj, "bsg"); 182 cdev_device_del(&bd->cdev, &bd->device); 183 put_device(&bd->device); 184 } 185 EXPORT_SYMBOL_GPL(bsg_unregister_queue); 186 187 struct bsg_device *bsg_register_queue(struct request_queue *q, 188 struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn) 189 { 190 struct bsg_device *bd; 191 int ret; 192 193 bd = kzalloc(sizeof(*bd), GFP_KERNEL); 194 if (!bd) 195 return ERR_PTR(-ENOMEM); 196 bd->max_queue = BSG_DEFAULT_CMDS; 197 bd->reserved_size = INT_MAX; 198 bd->queue = q; 199 bd->sg_io_fn = sg_io_fn; 200 201 ret = ida_alloc_max(&bsg_minor_ida, BSG_MAX_DEVS - 1, GFP_KERNEL); 202 if (ret < 0) { 203 if (ret == -ENOSPC) 204 dev_err(parent, "bsg: too many bsg devices\n"); 205 kfree(bd); 206 return ERR_PTR(ret); 207 } 208 bd->device.devt = MKDEV(bsg_major, ret); 209 bd->device.class = bsg_class; 210 bd->device.parent = parent; 211 bd->device.release = bsg_device_release; 212 dev_set_name(&bd->device, "%s", name); 213 device_initialize(&bd->device); 214 215 cdev_init(&bd->cdev, &bsg_fops); 216 bd->cdev.owner = THIS_MODULE; 217 ret = cdev_device_add(&bd->cdev, &bd->device); 218 if (ret) 219 goto out_put_device; 220 221 if (q->disk && q->disk->queue_kobj.sd) { 222 ret = sysfs_create_link(&q->disk->queue_kobj, &bd->device.kobj, 223 "bsg"); 224 if (ret) 225 goto out_device_del; 226 } 227 228 return bd; 229 230 out_device_del: 231 cdev_device_del(&bd->cdev, &bd->device); 232 out_put_device: 233 put_device(&bd->device); 234 return ERR_PTR(ret); 235 } 236 EXPORT_SYMBOL_GPL(bsg_register_queue); 237 238 static char *bsg_devnode(const struct device *dev, umode_t *mode) 239 { 240 return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev)); 241 } 242 243 static int __init bsg_init(void) 244 { 245 dev_t devid; 246 int ret; 247 248 bsg_class = class_create(THIS_MODULE, "bsg"); 249 if (IS_ERR(bsg_class)) 250 return PTR_ERR(bsg_class); 251 bsg_class->devnode = bsg_devnode; 252 253 ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg"); 254 if (ret) 255 goto destroy_bsg_class; 256 bsg_major = MAJOR(devid); 257 258 printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION 259 " loaded (major %d)\n", bsg_major); 260 return 0; 261 262 destroy_bsg_class: 263 class_destroy(bsg_class); 264 return ret; 265 } 266 267 MODULE_AUTHOR("Jens Axboe"); 268 MODULE_DESCRIPTION(BSG_DESCRIPTION); 269 MODULE_LICENSE("GPL"); 270 271 device_initcall(bsg_init); 272