| 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(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); |