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 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); 278