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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#include <linux/io_uring/cmd.h>
16
17#include <scsi/scsi.h>
18#include <scsi/scsi_ioctl.h>
19#include <scsi/sg.h>
20
21#define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
22#define BSG_VERSION "0.4"
23
24struct bsg_device {
25 struct request_queue *queue;
26 struct device device;
27 struct cdev cdev;
28 int max_queue;
29 unsigned int timeout;
30 unsigned int reserved_size;
31 bsg_sg_io_fn *sg_io_fn;
32 bsg_uring_cmd_fn *uring_cmd_fn;
33};
34
35static inline struct bsg_device *to_bsg_device(struct inode *inode)
36{
37 return container_of(inode->i_cdev, struct bsg_device, cdev);
38}
39
40#define BSG_DEFAULT_CMDS 64
41#define BSG_MAX_DEVS (1 << MINORBITS)
42
43static DEFINE_IDA(bsg_minor_ida);
44static const struct class bsg_class;
45static int bsg_major;
46
47static unsigned int bsg_timeout(struct bsg_device *bd, struct sg_io_v4 *hdr)
48{
49 unsigned int timeout = BLK_DEFAULT_SG_TIMEOUT;
50
51 if (hdr->timeout)
52 timeout = msecs_to_jiffies(hdr->timeout);
53 else if (bd->timeout)
54 timeout = bd->timeout;
55
56 return max_t(unsigned int, timeout, BLK_MIN_SG_TIMEOUT);
57}
58
59static int bsg_sg_io(struct bsg_device *bd, bool open_for_write,
60 void __user *uarg)
61{
62 struct sg_io_v4 hdr;
63 int ret;
64
65 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
66 return -EFAULT;
67 if (hdr.guard != 'Q')
68 return -EINVAL;
69 ret = bd->sg_io_fn(bd->queue, &hdr, open_for_write,
70 bsg_timeout(bd, &hdr));
71 if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
72 return -EFAULT;
73 return ret;
74}
75
76static int bsg_open(struct inode *inode, struct file *file)
77{
78 if (!blk_get_queue(to_bsg_device(inode)->queue))
79 return -ENXIO;
80 return 0;
81}
82
83static int bsg_release(struct inode *inode, struct file *file)
84{
85 blk_put_queue(to_bsg_device(inode)->queue);
86 return 0;
87}
88
89static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
90{
91 return put_user(READ_ONCE(bd->max_queue), uarg);
92}
93
94static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
95{
96 int max_queue;
97
98 if (get_user(max_queue, uarg))
99 return -EFAULT;
100 if (max_queue < 1)
101 return -EINVAL;
102 WRITE_ONCE(bd->max_queue, max_queue);
103 return 0;
104}
105
106static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
107{
108 struct bsg_device *bd = to_bsg_device(file_inode(file));
109 struct request_queue *q = bd->queue;
110 void __user *uarg = (void __user *) arg;
111 int __user *intp = uarg;
112 int val;
113
114 switch (cmd) {
115 /*
116 * Our own ioctls
117 */
118 case SG_GET_COMMAND_Q:
119 return bsg_get_command_q(bd, uarg);
120 case SG_SET_COMMAND_Q:
121 return bsg_set_command_q(bd, uarg);
122
123 /*
124 * SCSI/sg ioctls
125 */
126 case SG_GET_VERSION_NUM:
127 return put_user(30527, intp);
128 case SCSI_IOCTL_GET_IDLUN:
129 return put_user(0, intp);
130 case SCSI_IOCTL_GET_BUS_NUMBER:
131 return put_user(0, intp);
132 case SG_SET_TIMEOUT:
133 if (get_user(val, intp))
134 return -EFAULT;
135 bd->timeout = clock_t_to_jiffies(val);
136 return 0;
137 case SG_GET_TIMEOUT:
138 return jiffies_to_clock_t(bd->timeout);
139 case SG_GET_RESERVED_SIZE:
140 return put_user(min(bd->reserved_size, queue_max_bytes(q)),
141 intp);
142 case SG_SET_RESERVED_SIZE:
143 if (get_user(val, intp))
144 return -EFAULT;
145 if (val < 0)
146 return -EINVAL;
147 bd->reserved_size =
148 min_t(unsigned int, val, queue_max_bytes(q));
149 return 0;
150 case SG_EMULATED_HOST:
151 return put_user(1, intp);
152 case SG_IO:
153 return bsg_sg_io(bd, file->f_mode & FMODE_WRITE, uarg);
154 case SCSI_IOCTL_SEND_COMMAND:
155 pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n",
156 current->comm);
157 return -EINVAL;
158 default:
159 return -ENOTTY;
160 }
161}
162
163static int bsg_check_uring_features(unsigned int issue_flags)
164{
165 /* BSG passthrough requires big SQE/CQE support */
166 if ((issue_flags & (IO_URING_F_SQE128|IO_URING_F_CQE32)) !=
167 (IO_URING_F_SQE128|IO_URING_F_CQE32))
168 return -EOPNOTSUPP;
169 return 0;
170}
171
172static int bsg_uring_cmd(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
173{
174 struct bsg_device *bd = to_bsg_device(file_inode(ioucmd->file));
175 bool open_for_write = ioucmd->file->f_mode & FMODE_WRITE;
176 struct request_queue *q = bd->queue;
177 int ret;
178
179 ret = bsg_check_uring_features(issue_flags);
180 if (ret)
181 return ret;
182
183 if (!bd->uring_cmd_fn)
184 return -EOPNOTSUPP;
185
186 return bd->uring_cmd_fn(q, ioucmd, issue_flags, open_for_write);
187}
188
189static const struct file_operations bsg_fops = {
190 .open = bsg_open,
191 .release = bsg_release,
192 .unlocked_ioctl = bsg_ioctl,
193 .compat_ioctl = compat_ptr_ioctl,
194 .uring_cmd = bsg_uring_cmd,
195 .owner = THIS_MODULE,
196 .llseek = default_llseek,
197};
198
199static void bsg_device_release(struct device *dev)
200{
201 struct bsg_device *bd = container_of(dev, struct bsg_device, device);
202
203 ida_free(&bsg_minor_ida, MINOR(bd->device.devt));
204 kfree(bd);
205}
206
207void bsg_unregister_queue(struct bsg_device *bd)
208{
209 struct gendisk *disk = bd->queue->disk;
210
211 if (disk && disk->queue_kobj.sd)
212 sysfs_remove_link(&disk->queue_kobj, "bsg");
213 cdev_device_del(&bd->cdev, &bd->device);
214 put_device(&bd->device);
215}
216EXPORT_SYMBOL_GPL(bsg_unregister_queue);
217
218struct bsg_device *bsg_register_queue(struct request_queue *q,
219 struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn,
220 bsg_uring_cmd_fn *uring_cmd_fn)
221{
222 struct bsg_device *bd;
223 int ret;
224
225 bd = kzalloc_obj(*bd);
226 if (!bd)
227 return ERR_PTR(-ENOMEM);
228 bd->max_queue = BSG_DEFAULT_CMDS;
229 bd->reserved_size = INT_MAX;
230 bd->queue = q;
231 bd->sg_io_fn = sg_io_fn;
232 bd->uring_cmd_fn = uring_cmd_fn;
233
234 ret = ida_alloc_max(&bsg_minor_ida, BSG_MAX_DEVS - 1, GFP_KERNEL);
235 if (ret < 0) {
236 if (ret == -ENOSPC)
237 dev_err(parent, "bsg: too many bsg devices\n");
238 kfree(bd);
239 return ERR_PTR(ret);
240 }
241 bd->device.devt = MKDEV(bsg_major, ret);
242 bd->device.class = &bsg_class;
243 bd->device.parent = parent;
244 bd->device.release = bsg_device_release;
245 dev_set_name(&bd->device, "%s", name);
246 device_initialize(&bd->device);
247
248 cdev_init(&bd->cdev, &bsg_fops);
249 bd->cdev.owner = THIS_MODULE;
250 ret = cdev_device_add(&bd->cdev, &bd->device);
251 if (ret)
252 goto out_put_device;
253
254 if (q->disk && q->disk->queue_kobj.sd) {
255 ret = sysfs_create_link(&q->disk->queue_kobj, &bd->device.kobj,
256 "bsg");
257 if (ret)
258 goto out_device_del;
259 }
260
261 return bd;
262
263out_device_del:
264 cdev_device_del(&bd->cdev, &bd->device);
265out_put_device:
266 put_device(&bd->device);
267 return ERR_PTR(ret);
268}
269EXPORT_SYMBOL_GPL(bsg_register_queue);
270
271static char *bsg_devnode(const struct device *dev, umode_t *mode)
272{
273 return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
274}
275
276static const struct class bsg_class = {
277 .name = "bsg",
278 .devnode = bsg_devnode,
279};
280
281static int __init bsg_init(void)
282{
283 dev_t devid;
284 int ret;
285
286 ret = class_register(&bsg_class);
287 if (ret)
288 return ret;
289
290 ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
291 if (ret)
292 goto destroy_bsg_class;
293 bsg_major = MAJOR(devid);
294
295 printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
296 " loaded (major %d)\n", bsg_major);
297 return 0;
298
299destroy_bsg_class:
300 class_unregister(&bsg_class);
301 return ret;
302}
303
304MODULE_AUTHOR("Jens Axboe");
305MODULE_DESCRIPTION(BSG_DESCRIPTION);
306MODULE_LICENSE("GPL");
307
308device_initcall(bsg_init);