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
23struct 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
33static 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
41static DEFINE_IDA(bsg_minor_ida);
42static const struct class bsg_class;
43static int bsg_major;
44
45static 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
57static 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
74static 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
81static int bsg_release(struct inode *inode, struct file *file)
82{
83	blk_put_queue(to_bsg_device(inode)->queue);
84	return 0;
85}
86
87static 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
92static 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
104static 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
161static 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
170static 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
178void 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}
187EXPORT_SYMBOL_GPL(bsg_unregister_queue);
188
189struct 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
232out_device_del:
233	cdev_device_del(&bd->cdev, &bd->device);
234out_put_device:
235	put_device(&bd->device);
236	return ERR_PTR(ret);
237}
238EXPORT_SYMBOL_GPL(bsg_register_queue);
239
240static char *bsg_devnode(const struct device *dev, umode_t *mode)
241{
242	return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
243}
244
245static const struct class bsg_class = {
246	.name		= "bsg",
247	.devnode	= bsg_devnode,
248};
249
250static 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
268destroy_bsg_class:
269	class_unregister(&bsg_class);
270	return ret;
271}
272
273MODULE_AUTHOR("Jens Axboe");
274MODULE_DESCRIPTION(BSG_DESCRIPTION);
275MODULE_LICENSE("GPL");
276
277device_initcall(bsg_init);
278