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 (1 << MINORBITS) |
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(m: 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(to: &hdr, from: uarg, n: 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: &hdr)); |
69 | if (!ret && copy_to_user(to: uarg, from: &hdr, n: 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(inode: file_inode(f: 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(x: val); |
134 | return 0; |
135 | case SG_GET_TIMEOUT: |
136 | return jiffies_to_clock_t(x: 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, open_for_write: 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(objp: 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(kobj: &disk->queue_kobj, name: "bsg" ); |
184 | cdev_device_del(cdev: &bd->cdev, dev: &bd->device); |
185 | put_device(dev: &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(size: sizeof(*bd), GFP_KERNEL); |
196 | if (!bd) |
197 | return ERR_PTR(error: -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(ida: &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(objp: bd); |
208 | return ERR_PTR(error: 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(dev: &bd->device, name: "%s" , name); |
215 | device_initialize(dev: &bd->device); |
216 | |
217 | cdev_init(&bd->cdev, &bsg_fops); |
218 | bd->cdev.owner = THIS_MODULE; |
219 | ret = cdev_device_add(cdev: &bd->cdev, dev: &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(kobj: &q->disk->queue_kobj, target: &bd->device.kobj, |
225 | name: "bsg" ); |
226 | if (ret) |
227 | goto out_device_del; |
228 | } |
229 | |
230 | return bd; |
231 | |
232 | out_device_del: |
233 | cdev_device_del(cdev: &bd->cdev, dev: &bd->device); |
234 | out_put_device: |
235 | put_device(dev: &bd->device); |
236 | return ERR_PTR(error: 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, fmt: "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(class: &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(class: &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 | |