1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/compat.h>
4#include <linux/console.h>
5#include <linux/fb.h>
6#include <linux/fbcon.h>
7#include <linux/major.h>
8
9#include "fb_internal.h"
10
11/*
12 * We hold a reference to the fb_info in file->private_data,
13 * but if the current registered fb has changed, we don't
14 * actually want to use it.
15 *
16 * So look up the fb_info using the inode minor number,
17 * and just verify it against the reference we have.
18 */
19static struct fb_info *file_fb_info(struct file *file)
20{
21 struct inode *inode = file_inode(f: file);
22 int fbidx = iminor(inode);
23 struct fb_info *info = registered_fb[fbidx];
24
25 if (info != file->private_data)
26 info = NULL;
27 return info;
28}
29
30static ssize_t fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
31{
32 struct fb_info *info = file_fb_info(file);
33
34 if (!info)
35 return -ENODEV;
36
37 if (fb_WARN_ON_ONCE(info, !info->fbops->fb_read))
38 return -EINVAL;
39
40 if (info->state != FBINFO_STATE_RUNNING)
41 return -EPERM;
42
43 return info->fbops->fb_read(info, buf, count, ppos);
44}
45
46static ssize_t fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
47{
48 struct fb_info *info = file_fb_info(file);
49
50 if (!info)
51 return -ENODEV;
52
53 if (fb_WARN_ON_ONCE(info, !info->fbops->fb_write))
54 return -EINVAL;
55
56 if (info->state != FBINFO_STATE_RUNNING)
57 return -EPERM;
58
59 return info->fbops->fb_write(info, buf, count, ppos);
60}
61
62static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
63 unsigned long arg)
64{
65 const struct fb_ops *fb;
66 struct fb_var_screeninfo var;
67 struct fb_fix_screeninfo fix;
68 struct fb_cmap cmap_from;
69 struct fb_cmap_user cmap;
70 void __user *argp = (void __user *)arg;
71 long ret = 0;
72
73 switch (cmd) {
74 case FBIOGET_VSCREENINFO:
75 lock_fb_info(info);
76 var = info->var;
77 unlock_fb_info(info);
78
79 ret = copy_to_user(to: argp, from: &var, n: sizeof(var)) ? -EFAULT : 0;
80 break;
81 case FBIOPUT_VSCREENINFO:
82 if (copy_from_user(to: &var, from: argp, n: sizeof(var)))
83 return -EFAULT;
84 /* only for kernel-internal use */
85 var.activate &= ~FB_ACTIVATE_KD_TEXT;
86 console_lock();
87 lock_fb_info(info);
88 ret = fbcon_modechange_possible(info, var: &var);
89 if (!ret)
90 ret = fb_set_var(info, var: &var);
91 if (!ret)
92 fbcon_update_vcs(info, all: var.activate & FB_ACTIVATE_ALL);
93 unlock_fb_info(info);
94 console_unlock();
95 if (!ret && copy_to_user(to: argp, from: &var, n: sizeof(var)))
96 ret = -EFAULT;
97 break;
98 case FBIOGET_FSCREENINFO:
99 lock_fb_info(info);
100 memcpy(&fix, &info->fix, sizeof(fix));
101 if (info->flags & FBINFO_HIDE_SMEM_START)
102 fix.smem_start = 0;
103 unlock_fb_info(info);
104
105 ret = copy_to_user(to: argp, from: &fix, n: sizeof(fix)) ? -EFAULT : 0;
106 break;
107 case FBIOPUTCMAP:
108 if (copy_from_user(to: &cmap, from: argp, n: sizeof(cmap)))
109 return -EFAULT;
110 ret = fb_set_user_cmap(cmap: &cmap, fb_info: info);
111 break;
112 case FBIOGETCMAP:
113 if (copy_from_user(to: &cmap, from: argp, n: sizeof(cmap)))
114 return -EFAULT;
115 lock_fb_info(info);
116 cmap_from = info->cmap;
117 unlock_fb_info(info);
118 ret = fb_cmap_to_user(from: &cmap_from, to: &cmap);
119 break;
120 case FBIOPAN_DISPLAY:
121 if (copy_from_user(to: &var, from: argp, n: sizeof(var)))
122 return -EFAULT;
123 console_lock();
124 lock_fb_info(info);
125 ret = fb_pan_display(info, var: &var);
126 unlock_fb_info(info);
127 console_unlock();
128 if (ret == 0 && copy_to_user(to: argp, from: &var, n: sizeof(var)))
129 return -EFAULT;
130 break;
131 case FBIO_CURSOR:
132 ret = -EINVAL;
133 break;
134 case FBIOGET_CON2FBMAP:
135 ret = fbcon_get_con2fb_map_ioctl(argp);
136 break;
137 case FBIOPUT_CON2FBMAP:
138 ret = fbcon_set_con2fb_map_ioctl(argp);
139 break;
140 case FBIOBLANK:
141 if (arg > FB_BLANK_POWERDOWN)
142 return -EINVAL;
143 console_lock();
144 lock_fb_info(info);
145 ret = fb_blank(info, blank: arg);
146 /* might again call into fb_blank */
147 fbcon_fb_blanked(info, blank: arg);
148 unlock_fb_info(info);
149 console_unlock();
150 break;
151 default:
152 lock_fb_info(info);
153 fb = info->fbops;
154 if (fb->fb_ioctl)
155 ret = fb->fb_ioctl(info, cmd, arg);
156 else
157 ret = -ENOTTY;
158 unlock_fb_info(info);
159 }
160 return ret;
161}
162
163static long fb_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
164{
165 struct fb_info *info = file_fb_info(file);
166
167 if (!info)
168 return -ENODEV;
169 return do_fb_ioctl(info, cmd, arg);
170}
171
172#ifdef CONFIG_COMPAT
173struct fb_fix_screeninfo32 {
174 char id[16];
175 compat_caddr_t smem_start;
176 u32 smem_len;
177 u32 type;
178 u32 type_aux;
179 u32 visual;
180 u16 xpanstep;
181 u16 ypanstep;
182 u16 ywrapstep;
183 u32 line_length;
184 compat_caddr_t mmio_start;
185 u32 mmio_len;
186 u32 accel;
187 u16 reserved[3];
188};
189
190struct fb_cmap32 {
191 u32 start;
192 u32 len;
193 compat_caddr_t red;
194 compat_caddr_t green;
195 compat_caddr_t blue;
196 compat_caddr_t transp;
197};
198
199static int fb_getput_cmap(struct fb_info *info, unsigned int cmd,
200 unsigned long arg)
201{
202 struct fb_cmap32 cmap32;
203 struct fb_cmap cmap_from;
204 struct fb_cmap_user cmap;
205
206 if (copy_from_user(to: &cmap32, from: compat_ptr(uptr: arg), n: sizeof(cmap32)))
207 return -EFAULT;
208
209 cmap = (struct fb_cmap_user) {
210 .start = cmap32.start,
211 .len = cmap32.len,
212 .red = compat_ptr(uptr: cmap32.red),
213 .green = compat_ptr(uptr: cmap32.green),
214 .blue = compat_ptr(uptr: cmap32.blue),
215 .transp = compat_ptr(uptr: cmap32.transp),
216 };
217
218 if (cmd == FBIOPUTCMAP)
219 return fb_set_user_cmap(cmap: &cmap, fb_info: info);
220
221 lock_fb_info(info);
222 cmap_from = info->cmap;
223 unlock_fb_info(info);
224
225 return fb_cmap_to_user(from: &cmap_from, to: &cmap);
226}
227
228static int do_fscreeninfo_to_user(struct fb_fix_screeninfo *fix,
229 struct fb_fix_screeninfo32 __user *fix32)
230{
231 __u32 data;
232 int err;
233
234 err = copy_to_user(to: &fix32->id, from: &fix->id, n: sizeof(fix32->id));
235
236 data = (__u32) (unsigned long) fix->smem_start;
237 err |= put_user(data, &fix32->smem_start);
238
239 err |= put_user(fix->smem_len, &fix32->smem_len);
240 err |= put_user(fix->type, &fix32->type);
241 err |= put_user(fix->type_aux, &fix32->type_aux);
242 err |= put_user(fix->visual, &fix32->visual);
243 err |= put_user(fix->xpanstep, &fix32->xpanstep);
244 err |= put_user(fix->ypanstep, &fix32->ypanstep);
245 err |= put_user(fix->ywrapstep, &fix32->ywrapstep);
246 err |= put_user(fix->line_length, &fix32->line_length);
247
248 data = (__u32) (unsigned long) fix->mmio_start;
249 err |= put_user(data, &fix32->mmio_start);
250
251 err |= put_user(fix->mmio_len, &fix32->mmio_len);
252 err |= put_user(fix->accel, &fix32->accel);
253 err |= copy_to_user(to: fix32->reserved, from: fix->reserved,
254 n: sizeof(fix->reserved));
255
256 if (err)
257 return -EFAULT;
258 return 0;
259}
260
261static int fb_get_fscreeninfo(struct fb_info *info, unsigned int cmd,
262 unsigned long arg)
263{
264 struct fb_fix_screeninfo fix;
265
266 lock_fb_info(info);
267 fix = info->fix;
268 if (info->flags & FBINFO_HIDE_SMEM_START)
269 fix.smem_start = 0;
270 unlock_fb_info(info);
271 return do_fscreeninfo_to_user(fix: &fix, fix32: compat_ptr(uptr: arg));
272}
273
274static long fb_compat_ioctl(struct file *file, unsigned int cmd,
275 unsigned long arg)
276{
277 struct fb_info *info = file_fb_info(file);
278 const struct fb_ops *fb;
279 long ret = -ENOIOCTLCMD;
280
281 if (!info)
282 return -ENODEV;
283 fb = info->fbops;
284 switch (cmd) {
285 case FBIOGET_VSCREENINFO:
286 case FBIOPUT_VSCREENINFO:
287 case FBIOPAN_DISPLAY:
288 case FBIOGET_CON2FBMAP:
289 case FBIOPUT_CON2FBMAP:
290 arg = (unsigned long) compat_ptr(uptr: arg);
291 fallthrough;
292 case FBIOBLANK:
293 ret = do_fb_ioctl(info, cmd, arg);
294 break;
295
296 case FBIOGET_FSCREENINFO:
297 ret = fb_get_fscreeninfo(info, cmd, arg);
298 break;
299
300 case FBIOGETCMAP:
301 case FBIOPUTCMAP:
302 ret = fb_getput_cmap(info, cmd, arg);
303 break;
304
305 default:
306 if (fb->fb_compat_ioctl)
307 ret = fb->fb_compat_ioctl(info, cmd, arg);
308 break;
309 }
310 return ret;
311}
312#endif
313
314static int fb_mmap(struct file *file, struct vm_area_struct *vma)
315{
316 struct fb_info *info = file_fb_info(file);
317 int res;
318
319 if (!info)
320 return -ENODEV;
321
322 if (fb_WARN_ON_ONCE(info, !info->fbops->fb_mmap))
323 return -ENODEV;
324
325 mutex_lock(&info->mm_lock);
326 res = info->fbops->fb_mmap(info, vma);
327 mutex_unlock(lock: &info->mm_lock);
328
329 return res;
330}
331
332static int fb_open(struct inode *inode, struct file *file)
333__acquires(&info->lock)
334__releases(&info->lock)
335{
336 int fbidx = iminor(inode);
337 struct fb_info *info;
338 int res = 0;
339
340 info = get_fb_info(idx: fbidx);
341 if (!info) {
342 request_module("fb%d", fbidx);
343 info = get_fb_info(idx: fbidx);
344 if (!info)
345 return -ENODEV;
346 }
347 if (IS_ERR(ptr: info))
348 return PTR_ERR(ptr: info);
349
350 lock_fb_info(info);
351 if (!try_module_get(module: info->fbops->owner)) {
352 res = -ENODEV;
353 goto out;
354 }
355 file->private_data = info;
356 if (info->fbops->fb_open) {
357 res = info->fbops->fb_open(info, 1);
358 if (res)
359 module_put(module: info->fbops->owner);
360 }
361#ifdef CONFIG_FB_DEFERRED_IO
362 if (info->fbdefio)
363 fb_deferred_io_open(info, inode, file);
364#endif
365out:
366 unlock_fb_info(info);
367 if (res)
368 put_fb_info(fb_info: info);
369 return res;
370}
371
372static int fb_release(struct inode *inode, struct file *file)
373__acquires(&info->lock)
374__releases(&info->lock)
375{
376 struct fb_info * const info = file->private_data;
377
378 lock_fb_info(info);
379#if IS_ENABLED(CONFIG_FB_DEFERRED_IO)
380 if (info->fbdefio)
381 fb_deferred_io_release(info);
382#endif
383 if (info->fbops->fb_release)
384 info->fbops->fb_release(info, 1);
385 module_put(module: info->fbops->owner);
386 unlock_fb_info(info);
387 put_fb_info(fb_info: info);
388 return 0;
389}
390
391#if defined(CONFIG_FB_PROVIDE_GET_FB_UNMAPPED_AREA) && !defined(CONFIG_MMU)
392static unsigned long get_fb_unmapped_area(struct file *filp,
393 unsigned long addr, unsigned long len,
394 unsigned long pgoff, unsigned long flags)
395{
396 struct fb_info * const info = filp->private_data;
397 unsigned long fb_size = PAGE_ALIGN(info->fix.smem_len);
398
399 if (pgoff > fb_size || len > fb_size - pgoff)
400 return -EINVAL;
401
402 return (unsigned long)info->screen_base + pgoff;
403}
404#endif
405
406static const struct file_operations fb_fops = {
407 .owner = THIS_MODULE,
408 .read = fb_read,
409 .write = fb_write,
410 .unlocked_ioctl = fb_ioctl,
411#ifdef CONFIG_COMPAT
412 .compat_ioctl = fb_compat_ioctl,
413#endif
414 .mmap = fb_mmap,
415 .open = fb_open,
416 .release = fb_release,
417#if defined(HAVE_ARCH_FB_UNMAPPED_AREA) || \
418 (defined(CONFIG_FB_PROVIDE_GET_FB_UNMAPPED_AREA) && \
419 !defined(CONFIG_MMU))
420 .get_unmapped_area = get_fb_unmapped_area,
421#endif
422#ifdef CONFIG_FB_DEFERRED_IO
423 .fsync = fb_deferred_io_fsync,
424#endif
425 .llseek = default_llseek,
426};
427
428int fb_register_chrdev(void)
429{
430 int ret;
431
432 ret = register_chrdev(FB_MAJOR, name: "fb", fops: &fb_fops);
433 if (ret) {
434 pr_err("Unable to get major %d for fb devs\n", FB_MAJOR);
435 return ret;
436 }
437
438 return ret;
439}
440
441void fb_unregister_chrdev(void)
442{
443 unregister_chrdev(FB_MAJOR, name: "fb");
444}
445

source code of linux/drivers/video/fbdev/core/fb_chrdev.c