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
to_bsg_device(struct inode * inode)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
bsg_timeout(struct bsg_device * bd,struct sg_io_v4 * hdr)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
bsg_sg_io(struct bsg_device * bd,fmode_t mode,void __user * uarg)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
bsg_open(struct inode * inode,struct file * file)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
bsg_release(struct inode * inode,struct file * file)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
bsg_get_command_q(struct bsg_device * bd,int __user * uarg)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
bsg_set_command_q(struct bsg_device * bd,int __user * uarg)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
bsg_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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
bsg_device_release(struct device * dev)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_simple_remove(&bsg_minor_ida, MINOR(bd->device.devt));
173 kfree(bd);
174 }
175
bsg_unregister_queue(struct bsg_device * bd)176 void bsg_unregister_queue(struct bsg_device *bd)
177 {
178 if (bd->queue->kobj.sd)
179 sysfs_remove_link(&bd->queue->kobj, "bsg");
180 cdev_device_del(&bd->cdev, &bd->device);
181 put_device(&bd->device);
182 }
183 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
184
bsg_register_queue(struct request_queue * q,struct device * parent,const char * name,bsg_sg_io_fn * sg_io_fn)185 struct bsg_device *bsg_register_queue(struct request_queue *q,
186 struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn)
187 {
188 struct bsg_device *bd;
189 int ret;
190
191 bd = kzalloc(sizeof(*bd), GFP_KERNEL);
192 if (!bd)
193 return ERR_PTR(-ENOMEM);
194 bd->max_queue = BSG_DEFAULT_CMDS;
195 bd->reserved_size = INT_MAX;
196 bd->queue = q;
197 bd->sg_io_fn = sg_io_fn;
198
199 ret = ida_simple_get(&bsg_minor_ida, 0, BSG_MAX_DEVS, GFP_KERNEL);
200 if (ret < 0) {
201 if (ret == -ENOSPC)
202 dev_err(parent, "bsg: too many bsg devices\n");
203 kfree(bd);
204 return ERR_PTR(ret);
205 }
206 bd->device.devt = MKDEV(bsg_major, ret);
207 bd->device.class = bsg_class;
208 bd->device.parent = parent;
209 bd->device.release = bsg_device_release;
210 dev_set_name(&bd->device, "%s", name);
211 device_initialize(&bd->device);
212
213 cdev_init(&bd->cdev, &bsg_fops);
214 bd->cdev.owner = THIS_MODULE;
215 ret = cdev_device_add(&bd->cdev, &bd->device);
216 if (ret)
217 goto out_put_device;
218
219 if (q->kobj.sd) {
220 ret = sysfs_create_link(&q->kobj, &bd->device.kobj, "bsg");
221 if (ret)
222 goto out_device_del;
223 }
224
225 return bd;
226
227 out_device_del:
228 cdev_device_del(&bd->cdev, &bd->device);
229 out_put_device:
230 put_device(&bd->device);
231 return ERR_PTR(ret);
232 }
233 EXPORT_SYMBOL_GPL(bsg_register_queue);
234
bsg_devnode(struct device * dev,umode_t * mode)235 static char *bsg_devnode(struct device *dev, umode_t *mode)
236 {
237 return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
238 }
239
bsg_init(void)240 static int __init bsg_init(void)
241 {
242 dev_t devid;
243 int ret;
244
245 bsg_class = class_create(THIS_MODULE, "bsg");
246 if (IS_ERR(bsg_class))
247 return PTR_ERR(bsg_class);
248 bsg_class->devnode = bsg_devnode;
249
250 ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
251 if (ret)
252 goto destroy_bsg_class;
253 bsg_major = MAJOR(devid);
254
255 printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
256 " loaded (major %d)\n", bsg_major);
257 return 0;
258
259 destroy_bsg_class:
260 class_destroy(bsg_class);
261 return ret;
262 }
263
264 MODULE_AUTHOR("Jens Axboe");
265 MODULE_DESCRIPTION(BSG_DESCRIPTION);
266 MODULE_LICENSE("GPL");
267
268 device_initcall(bsg_init);
269