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12#include <linux/mm.h>
13#include <linux/miscdevice.h>
14#include <linux/slab.h>
15#include <linux/vmalloc.h>
16#include <linux/mman.h>
17#include <linux/random.h>
18#include <linux/init.h>
19#include <linux/tty.h>
20#include <linux/capability.h>
21#include <linux/ptrace.h>
22#include <linux/device.h>
23#include <linux/highmem.h>
24#include <linux/backing-dev.h>
25#include <linux/shmem_fs.h>
26#include <linux/splice.h>
27#include <linux/pfn.h>
28#include <linux/export.h>
29#include <linux/io.h>
30#include <linux/uio.h>
31#include <linux/uaccess.h>
32#include <linux/security.h>
33
34#ifdef CONFIG_IA64
35# include <linux/efi.h>
36#endif
37
38#define DEVMEM_MINOR 1
39#define DEVPORT_MINOR 4
40
41static inline unsigned long size_inside_page(unsigned long start,
42 unsigned long size)
43{
44 unsigned long sz;
45
46 sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
47
48 return min(sz, size);
49}
50
51#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
52static inline int valid_phys_addr_range(phys_addr_t addr, size_t count)
53{
54 return addr + count <= __pa(high_memory);
55}
56
57static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
58{
59 return 1;
60}
61#endif
62
63#ifdef CONFIG_STRICT_DEVMEM
64static inline int page_is_allowed(unsigned long pfn)
65{
66 return devmem_is_allowed(pfn);
67}
68static inline int range_is_allowed(unsigned long pfn, unsigned long size)
69{
70 u64 from = ((u64)pfn) << PAGE_SHIFT;
71 u64 to = from + size;
72 u64 cursor = from;
73
74 while (cursor < to) {
75 if (!devmem_is_allowed(pfn))
76 return 0;
77 cursor += PAGE_SIZE;
78 pfn++;
79 }
80 return 1;
81}
82#else
83static inline int page_is_allowed(unsigned long pfn)
84{
85 return 1;
86}
87static inline int range_is_allowed(unsigned long pfn, unsigned long size)
88{
89 return 1;
90}
91#endif
92
93#ifndef unxlate_dev_mem_ptr
94#define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
95void __weak unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
96{
97}
98#endif
99
100static inline bool should_stop_iteration(void)
101{
102 if (need_resched())
103 cond_resched();
104 return fatal_signal_pending(current);
105}
106
107
108
109
110
111static ssize_t read_mem(struct file *file, char __user *buf,
112 size_t count, loff_t *ppos)
113{
114 phys_addr_t p = *ppos;
115 ssize_t read, sz;
116 void *ptr;
117 char *bounce;
118 int err;
119
120 if (p != *ppos)
121 return 0;
122
123 if (!valid_phys_addr_range(p, count))
124 return -EFAULT;
125 read = 0;
126#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
127
128 if (p < PAGE_SIZE) {
129 sz = size_inside_page(p, count);
130 if (sz > 0) {
131 if (clear_user(buf, sz))
132 return -EFAULT;
133 buf += sz;
134 p += sz;
135 count -= sz;
136 read += sz;
137 }
138 }
139#endif
140
141 bounce = kmalloc(PAGE_SIZE, GFP_KERNEL);
142 if (!bounce)
143 return -ENOMEM;
144
145 while (count > 0) {
146 unsigned long remaining;
147 int allowed, probe;
148
149 sz = size_inside_page(p, count);
150
151 err = -EPERM;
152 allowed = page_is_allowed(p >> PAGE_SHIFT);
153 if (!allowed)
154 goto failed;
155
156 err = -EFAULT;
157 if (allowed == 2) {
158
159 remaining = clear_user(buf, sz);
160 } else {
161
162
163
164
165
166 ptr = xlate_dev_mem_ptr(p);
167 if (!ptr)
168 goto failed;
169
170 probe = copy_from_kernel_nofault(bounce, ptr, sz);
171 unxlate_dev_mem_ptr(p, ptr);
172 if (probe)
173 goto failed;
174
175 remaining = copy_to_user(buf, bounce, sz);
176 }
177
178 if (remaining)
179 goto failed;
180
181 buf += sz;
182 p += sz;
183 count -= sz;
184 read += sz;
185 if (should_stop_iteration())
186 break;
187 }
188 kfree(bounce);
189
190 *ppos += read;
191 return read;
192
193failed:
194 kfree(bounce);
195 return err;
196}
197
198static ssize_t write_mem(struct file *file, const char __user *buf,
199 size_t count, loff_t *ppos)
200{
201 phys_addr_t p = *ppos;
202 ssize_t written, sz;
203 unsigned long copied;
204 void *ptr;
205
206 if (p != *ppos)
207 return -EFBIG;
208
209 if (!valid_phys_addr_range(p, count))
210 return -EFAULT;
211
212 written = 0;
213
214#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
215
216 if (p < PAGE_SIZE) {
217 sz = size_inside_page(p, count);
218
219 buf += sz;
220 p += sz;
221 count -= sz;
222 written += sz;
223 }
224#endif
225
226 while (count > 0) {
227 int allowed;
228
229 sz = size_inside_page(p, count);
230
231 allowed = page_is_allowed(p >> PAGE_SHIFT);
232 if (!allowed)
233 return -EPERM;
234
235
236 if (allowed == 1) {
237
238
239
240
241
242 ptr = xlate_dev_mem_ptr(p);
243 if (!ptr) {
244 if (written)
245 break;
246 return -EFAULT;
247 }
248
249 copied = copy_from_user(ptr, buf, sz);
250 unxlate_dev_mem_ptr(p, ptr);
251 if (copied) {
252 written += sz - copied;
253 if (written)
254 break;
255 return -EFAULT;
256 }
257 }
258
259 buf += sz;
260 p += sz;
261 count -= sz;
262 written += sz;
263 if (should_stop_iteration())
264 break;
265 }
266
267 *ppos += written;
268 return written;
269}
270
271int __weak phys_mem_access_prot_allowed(struct file *file,
272 unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
273{
274 return 1;
275}
276
277#ifndef __HAVE_PHYS_MEM_ACCESS_PROT
278
279
280
281
282
283
284#ifdef pgprot_noncached
285static int uncached_access(struct file *file, phys_addr_t addr)
286{
287#if defined(CONFIG_IA64)
288
289
290
291
292 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
293#else
294
295
296
297
298
299 if (file->f_flags & O_DSYNC)
300 return 1;
301 return addr >= __pa(high_memory);
302#endif
303}
304#endif
305
306static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
307 unsigned long size, pgprot_t vma_prot)
308{
309#ifdef pgprot_noncached
310 phys_addr_t offset = pfn << PAGE_SHIFT;
311
312 if (uncached_access(file, offset))
313 return pgprot_noncached(vma_prot);
314#endif
315 return vma_prot;
316}
317#endif
318
319#ifndef CONFIG_MMU
320static unsigned long get_unmapped_area_mem(struct file *file,
321 unsigned long addr,
322 unsigned long len,
323 unsigned long pgoff,
324 unsigned long flags)
325{
326 if (!valid_mmap_phys_addr_range(pgoff, len))
327 return (unsigned long) -EINVAL;
328 return pgoff << PAGE_SHIFT;
329}
330
331
332static unsigned memory_mmap_capabilities(struct file *file)
333{
334 return NOMMU_MAP_DIRECT |
335 NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
336}
337
338static unsigned zero_mmap_capabilities(struct file *file)
339{
340 return NOMMU_MAP_COPY;
341}
342
343
344static inline int private_mapping_ok(struct vm_area_struct *vma)
345{
346 return vma->vm_flags & VM_MAYSHARE;
347}
348#else
349
350static inline int private_mapping_ok(struct vm_area_struct *vma)
351{
352 return 1;
353}
354#endif
355
356static const struct vm_operations_struct mmap_mem_ops = {
357#ifdef CONFIG_HAVE_IOREMAP_PROT
358 .access = generic_access_phys
359#endif
360};
361
362static int mmap_mem(struct file *file, struct vm_area_struct *vma)
363{
364 size_t size = vma->vm_end - vma->vm_start;
365 phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
366
367
368 if (offset >> PAGE_SHIFT != vma->vm_pgoff)
369 return -EINVAL;
370
371
372 if (offset + (phys_addr_t)size - 1 < offset)
373 return -EINVAL;
374
375 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
376 return -EINVAL;
377
378 if (!private_mapping_ok(vma))
379 return -ENOSYS;
380
381 if (!range_is_allowed(vma->vm_pgoff, size))
382 return -EPERM;
383
384 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
385 &vma->vm_page_prot))
386 return -EINVAL;
387
388 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
389 size,
390 vma->vm_page_prot);
391
392 vma->vm_ops = &mmap_mem_ops;
393
394
395 if (remap_pfn_range(vma,
396 vma->vm_start,
397 vma->vm_pgoff,
398 size,
399 vma->vm_page_prot)) {
400 return -EAGAIN;
401 }
402 return 0;
403}
404
405static ssize_t read_port(struct file *file, char __user *buf,
406 size_t count, loff_t *ppos)
407{
408 unsigned long i = *ppos;
409 char __user *tmp = buf;
410
411 if (!access_ok(buf, count))
412 return -EFAULT;
413 while (count-- > 0 && i < 65536) {
414 if (__put_user(inb(i), tmp) < 0)
415 return -EFAULT;
416 i++;
417 tmp++;
418 }
419 *ppos = i;
420 return tmp-buf;
421}
422
423static ssize_t write_port(struct file *file, const char __user *buf,
424 size_t count, loff_t *ppos)
425{
426 unsigned long i = *ppos;
427 const char __user *tmp = buf;
428
429 if (!access_ok(buf, count))
430 return -EFAULT;
431 while (count-- > 0 && i < 65536) {
432 char c;
433
434 if (__get_user(c, tmp)) {
435 if (tmp > buf)
436 break;
437 return -EFAULT;
438 }
439 outb(c, i);
440 i++;
441 tmp++;
442 }
443 *ppos = i;
444 return tmp-buf;
445}
446
447static ssize_t read_null(struct file *file, char __user *buf,
448 size_t count, loff_t *ppos)
449{
450 return 0;
451}
452
453static ssize_t write_null(struct file *file, const char __user *buf,
454 size_t count, loff_t *ppos)
455{
456 return count;
457}
458
459static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
460{
461 return 0;
462}
463
464static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
465{
466 size_t count = iov_iter_count(from);
467 iov_iter_advance(from, count);
468 return count;
469}
470
471static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
472 struct splice_desc *sd)
473{
474 return sd->len;
475}
476
477static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
478 loff_t *ppos, size_t len, unsigned int flags)
479{
480 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
481}
482
483static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
484{
485 size_t written = 0;
486
487 while (iov_iter_count(iter)) {
488 size_t chunk = iov_iter_count(iter), n;
489
490 if (chunk > PAGE_SIZE)
491 chunk = PAGE_SIZE;
492 n = iov_iter_zero(chunk, iter);
493 if (!n && iov_iter_count(iter))
494 return written ? written : -EFAULT;
495 written += n;
496 if (signal_pending(current))
497 return written ? written : -ERESTARTSYS;
498 cond_resched();
499 }
500 return written;
501}
502
503static ssize_t read_zero(struct file *file, char __user *buf,
504 size_t count, loff_t *ppos)
505{
506 size_t cleared = 0;
507
508 while (count) {
509 size_t chunk = min_t(size_t, count, PAGE_SIZE);
510 size_t left;
511
512 left = clear_user(buf + cleared, chunk);
513 if (unlikely(left)) {
514 cleared += (chunk - left);
515 if (!cleared)
516 return -EFAULT;
517 break;
518 }
519 cleared += chunk;
520 count -= chunk;
521
522 if (signal_pending(current))
523 break;
524 cond_resched();
525 }
526
527 return cleared;
528}
529
530static int mmap_zero(struct file *file, struct vm_area_struct *vma)
531{
532#ifndef CONFIG_MMU
533 return -ENOSYS;
534#endif
535 if (vma->vm_flags & VM_SHARED)
536 return shmem_zero_setup(vma);
537 vma_set_anonymous(vma);
538 return 0;
539}
540
541static unsigned long get_unmapped_area_zero(struct file *file,
542 unsigned long addr, unsigned long len,
543 unsigned long pgoff, unsigned long flags)
544{
545#ifdef CONFIG_MMU
546 if (flags & MAP_SHARED) {
547
548
549
550
551
552
553 return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags);
554 }
555
556
557 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
558#else
559 return -ENOSYS;
560#endif
561}
562
563static ssize_t write_full(struct file *file, const char __user *buf,
564 size_t count, loff_t *ppos)
565{
566 return -ENOSPC;
567}
568
569
570
571
572
573
574static loff_t null_lseek(struct file *file, loff_t offset, int orig)
575{
576 return file->f_pos = 0;
577}
578
579
580
581
582
583
584
585
586
587static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
588{
589 loff_t ret;
590
591 inode_lock(file_inode(file));
592 switch (orig) {
593 case SEEK_CUR:
594 offset += file->f_pos;
595 fallthrough;
596 case SEEK_SET:
597
598 if ((unsigned long long)offset >= -MAX_ERRNO) {
599 ret = -EOVERFLOW;
600 break;
601 }
602 file->f_pos = offset;
603 ret = file->f_pos;
604 force_successful_syscall_return();
605 break;
606 default:
607 ret = -EINVAL;
608 }
609 inode_unlock(file_inode(file));
610 return ret;
611}
612
613static int open_port(struct inode *inode, struct file *filp)
614{
615 int rc;
616
617 if (!capable(CAP_SYS_RAWIO))
618 return -EPERM;
619
620 rc = security_locked_down(LOCKDOWN_DEV_MEM);
621 if (rc)
622 return rc;
623
624 if (iminor(inode) != DEVMEM_MINOR)
625 return 0;
626
627
628
629
630
631
632 filp->f_mapping = iomem_get_mapping();
633
634 return 0;
635}
636
637#define zero_lseek null_lseek
638#define full_lseek null_lseek
639#define write_zero write_null
640#define write_iter_zero write_iter_null
641#define open_mem open_port
642
643static const struct file_operations __maybe_unused mem_fops = {
644 .llseek = memory_lseek,
645 .read = read_mem,
646 .write = write_mem,
647 .mmap = mmap_mem,
648 .open = open_mem,
649#ifndef CONFIG_MMU
650 .get_unmapped_area = get_unmapped_area_mem,
651 .mmap_capabilities = memory_mmap_capabilities,
652#endif
653};
654
655static const struct file_operations null_fops = {
656 .llseek = null_lseek,
657 .read = read_null,
658 .write = write_null,
659 .read_iter = read_iter_null,
660 .write_iter = write_iter_null,
661 .splice_write = splice_write_null,
662};
663
664static const struct file_operations __maybe_unused port_fops = {
665 .llseek = memory_lseek,
666 .read = read_port,
667 .write = write_port,
668 .open = open_port,
669};
670
671static const struct file_operations zero_fops = {
672 .llseek = zero_lseek,
673 .write = write_zero,
674 .read_iter = read_iter_zero,
675 .read = read_zero,
676 .write_iter = write_iter_zero,
677 .mmap = mmap_zero,
678 .get_unmapped_area = get_unmapped_area_zero,
679#ifndef CONFIG_MMU
680 .mmap_capabilities = zero_mmap_capabilities,
681#endif
682};
683
684static const struct file_operations full_fops = {
685 .llseek = full_lseek,
686 .read_iter = read_iter_zero,
687 .write = write_full,
688};
689
690static const struct memdev {
691 const char *name;
692 umode_t mode;
693 const struct file_operations *fops;
694 fmode_t fmode;
695} devlist[] = {
696#ifdef CONFIG_DEVMEM
697 [DEVMEM_MINOR] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET },
698#endif
699 [3] = { "null", 0666, &null_fops, 0 },
700#ifdef CONFIG_DEVPORT
701 [4] = { "port", 0, &port_fops, 0 },
702#endif
703 [5] = { "zero", 0666, &zero_fops, 0 },
704 [7] = { "full", 0666, &full_fops, 0 },
705 [8] = { "random", 0666, &random_fops, 0 },
706 [9] = { "urandom", 0666, &urandom_fops, 0 },
707#ifdef CONFIG_PRINTK
708 [11] = { "kmsg", 0644, &kmsg_fops, 0 },
709#endif
710};
711
712static int memory_open(struct inode *inode, struct file *filp)
713{
714 int minor;
715 const struct memdev *dev;
716
717 minor = iminor(inode);
718 if (minor >= ARRAY_SIZE(devlist))
719 return -ENXIO;
720
721 dev = &devlist[minor];
722 if (!dev->fops)
723 return -ENXIO;
724
725 filp->f_op = dev->fops;
726 filp->f_mode |= dev->fmode;
727
728 if (dev->fops->open)
729 return dev->fops->open(inode, filp);
730
731 return 0;
732}
733
734static const struct file_operations memory_fops = {
735 .open = memory_open,
736 .llseek = noop_llseek,
737};
738
739static char *mem_devnode(struct device *dev, umode_t *mode)
740{
741 if (mode && devlist[MINOR(dev->devt)].mode)
742 *mode = devlist[MINOR(dev->devt)].mode;
743 return NULL;
744}
745
746static struct class *mem_class;
747
748static int __init chr_dev_init(void)
749{
750 int minor;
751
752 if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
753 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
754
755 mem_class = class_create(THIS_MODULE, "mem");
756 if (IS_ERR(mem_class))
757 return PTR_ERR(mem_class);
758
759 mem_class->devnode = mem_devnode;
760 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
761 if (!devlist[minor].name)
762 continue;
763
764
765
766
767 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
768 continue;
769
770 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
771 NULL, devlist[minor].name);
772 }
773
774 return tty_init();
775}
776
777fs_initcall(chr_dev_init);
778