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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/drivers/char/mem.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * Added devfs support.
8 * Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
9 * Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
10 */
11
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#define DEVMEM_MINOR 1
35#define DEVPORT_MINOR 4
36
37static inline unsigned long size_inside_page(unsigned long start,
38 unsigned long size)
39{
40 unsigned long sz;
41
42 sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
43
44 return min(sz, size);
45}
46
47#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
48static inline int valid_phys_addr_range(phys_addr_t addr, size_t count)
49{
50 return addr + count <= __pa(high_memory);
51}
52
53static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
54{
55 return 1;
56}
57#endif
58
59#ifdef CONFIG_STRICT_DEVMEM
60static inline int page_is_allowed(unsigned long pfn)
61{
62 return devmem_is_allowed(pfn);
63}
64static inline int range_is_allowed(unsigned long pfn, unsigned long size)
65{
66 u64 from = ((u64)pfn) << PAGE_SHIFT;
67 u64 to = from + size;
68 u64 cursor = from;
69
70 while (cursor < to) {
71 if (!devmem_is_allowed(pfn))
72 return 0;
73 cursor += PAGE_SIZE;
74 pfn++;
75 }
76 return 1;
77}
78#else
79static inline int page_is_allowed(unsigned long pfn)
80{
81 return 1;
82}
83static inline int range_is_allowed(unsigned long pfn, unsigned long size)
84{
85 return 1;
86}
87#endif
88
89static inline bool should_stop_iteration(void)
90{
91 if (need_resched())
92 cond_resched();
93 return signal_pending(current);
94}
95
96/*
97 * This funcion reads the *physical* memory. The f_pos points directly to the
98 * memory location.
99 */
100static ssize_t read_mem(struct file *file, char __user *buf,
101 size_t count, loff_t *ppos)
102{
103 phys_addr_t p = *ppos;
104 ssize_t read, sz;
105 void *ptr;
106 char *bounce;
107 int err;
108
109 if (p != *ppos)
110 return 0;
111
112 if (!valid_phys_addr_range(p, count))
113 return -EFAULT;
114 read = 0;
115#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
116 /* we don't have page 0 mapped on sparc and m68k.. */
117 if (p < PAGE_SIZE) {
118 sz = size_inside_page(p, count);
119 if (sz > 0) {
120 if (clear_user(buf, sz))
121 return -EFAULT;
122 buf += sz;
123 p += sz;
124 count -= sz;
125 read += sz;
126 }
127 }
128#endif
129
130 bounce = kmalloc(PAGE_SIZE, GFP_KERNEL);
131 if (!bounce)
132 return -ENOMEM;
133
134 while (count > 0) {
135 unsigned long remaining;
136 int allowed, probe;
137
138 sz = size_inside_page(p, count);
139
140 err = -EPERM;
141 allowed = page_is_allowed(p >> PAGE_SHIFT);
142 if (!allowed)
143 goto failed;
144
145 err = -EFAULT;
146 if (allowed == 2) {
147 /* Show zeros for restricted memory. */
148 remaining = clear_user(buf, sz);
149 } else {
150 /*
151 * On ia64 if a page has been mapped somewhere as
152 * uncached, then it must also be accessed uncached
153 * by the kernel or data corruption may occur.
154 */
155 ptr = xlate_dev_mem_ptr(p);
156 if (!ptr)
157 goto failed;
158
159 probe = copy_from_kernel_nofault(bounce, ptr, sz);
160 unxlate_dev_mem_ptr(p, ptr);
161 if (probe)
162 goto failed;
163
164 remaining = copy_to_user(buf, bounce, sz);
165 }
166
167 if (remaining)
168 goto failed;
169
170 buf += sz;
171 p += sz;
172 count -= sz;
173 read += sz;
174 if (should_stop_iteration())
175 break;
176 }
177 kfree(bounce);
178
179 *ppos += read;
180 return read;
181
182failed:
183 kfree(bounce);
184 return err;
185}
186
187static ssize_t write_mem(struct file *file, const char __user *buf,
188 size_t count, loff_t *ppos)
189{
190 phys_addr_t p = *ppos;
191 ssize_t written, sz;
192 unsigned long copied;
193 void *ptr;
194
195 if (p != *ppos)
196 return -EFBIG;
197
198 if (!valid_phys_addr_range(p, count))
199 return -EFAULT;
200
201 written = 0;
202
203#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
204 /* we don't have page 0 mapped on sparc and m68k.. */
205 if (p < PAGE_SIZE) {
206 sz = size_inside_page(p, count);
207 /* Hmm. Do something? */
208 buf += sz;
209 p += sz;
210 count -= sz;
211 written += sz;
212 }
213#endif
214
215 while (count > 0) {
216 int allowed;
217
218 sz = size_inside_page(p, count);
219
220 allowed = page_is_allowed(p >> PAGE_SHIFT);
221 if (!allowed)
222 return -EPERM;
223
224 /* Skip actual writing when a page is marked as restricted. */
225 if (allowed == 1) {
226 /*
227 * On ia64 if a page has been mapped somewhere as
228 * uncached, then it must also be accessed uncached
229 * by the kernel or data corruption may occur.
230 */
231 ptr = xlate_dev_mem_ptr(p);
232 if (!ptr) {
233 if (written)
234 break;
235 return -EFAULT;
236 }
237
238 copied = copy_from_user(ptr, buf, sz);
239 unxlate_dev_mem_ptr(p, ptr);
240 if (copied) {
241 written += sz - copied;
242 if (written)
243 break;
244 return -EFAULT;
245 }
246 }
247
248 buf += sz;
249 p += sz;
250 count -= sz;
251 written += sz;
252 if (should_stop_iteration())
253 break;
254 }
255
256 *ppos += written;
257 return written;
258}
259
260int __weak phys_mem_access_prot_allowed(struct file *file,
261 unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
262{
263 return 1;
264}
265
266#ifndef __HAVE_PHYS_MEM_ACCESS_PROT
267
268/*
269 * Architectures vary in how they handle caching for addresses
270 * outside of main memory.
271 *
272 */
273#ifdef pgprot_noncached
274static int uncached_access(struct file *file, phys_addr_t addr)
275{
276 /*
277 * Accessing memory above the top the kernel knows about or through a
278 * file pointer
279 * that was marked O_DSYNC will be done non-cached.
280 */
281 if (file->f_flags & O_DSYNC)
282 return 1;
283 return addr >= __pa(high_memory);
284}
285#endif
286
287static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
288 unsigned long size, pgprot_t vma_prot)
289{
290#ifdef pgprot_noncached
291 phys_addr_t offset = pfn << PAGE_SHIFT;
292
293 if (uncached_access(file, offset))
294 return pgprot_noncached(vma_prot);
295#endif
296 return vma_prot;
297}
298#endif
299
300#ifndef CONFIG_MMU
301static unsigned long get_unmapped_area_mem(struct file *file,
302 unsigned long addr,
303 unsigned long len,
304 unsigned long pgoff,
305 unsigned long flags)
306{
307 if (!valid_mmap_phys_addr_range(pgoff, len))
308 return (unsigned long) -EINVAL;
309 return pgoff << PAGE_SHIFT;
310}
311
312/* permit direct mmap, for read, write or exec */
313static unsigned memory_mmap_capabilities(struct file *file)
314{
315 return NOMMU_MAP_DIRECT |
316 NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
317}
318
319static unsigned zero_mmap_capabilities(struct file *file)
320{
321 return NOMMU_MAP_COPY;
322}
323
324/* can't do an in-place private mapping if there's no MMU */
325static inline int private_mapping_ok(struct vm_area_struct *vma)
326{
327 return is_nommu_shared_mapping(vma->vm_flags);
328}
329#else
330
331static inline int private_mapping_ok(struct vm_area_struct *vma)
332{
333 return 1;
334}
335#endif
336
337static const struct vm_operations_struct mmap_mem_ops = {
338#ifdef CONFIG_HAVE_IOREMAP_PROT
339 .access = generic_access_phys
340#endif
341};
342
343static int mmap_mem(struct file *file, struct vm_area_struct *vma)
344{
345 size_t size = vma->vm_end - vma->vm_start;
346 phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
347
348 /* Does it even fit in phys_addr_t? */
349 if (offset >> PAGE_SHIFT != vma->vm_pgoff)
350 return -EINVAL;
351
352 /* It's illegal to wrap around the end of the physical address space. */
353 if (offset + (phys_addr_t)size - 1 < offset)
354 return -EINVAL;
355
356 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
357 return -EINVAL;
358
359 if (!private_mapping_ok(vma))
360 return -ENOSYS;
361
362 if (!range_is_allowed(vma->vm_pgoff, size))
363 return -EPERM;
364
365 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
366 &vma->vm_page_prot))
367 return -EINVAL;
368
369 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
370 size,
371 vma->vm_page_prot);
372
373 vma->vm_ops = &mmap_mem_ops;
374
375 /* Remap-pfn-range will mark the range VM_IO */
376 if (remap_pfn_range(vma,
377 vma->vm_start,
378 vma->vm_pgoff,
379 size,
380 vma->vm_page_prot)) {
381 return -EAGAIN;
382 }
383 return 0;
384}
385
386static ssize_t read_port(struct file *file, char __user *buf,
387 size_t count, loff_t *ppos)
388{
389 unsigned long i = *ppos;
390 char __user *tmp = buf;
391
392 if (!access_ok(buf, count))
393 return -EFAULT;
394 while (count-- > 0 && i < 65536) {
395 if (__put_user(inb(i), tmp) < 0)
396 return -EFAULT;
397 i++;
398 tmp++;
399 }
400 *ppos = i;
401 return tmp-buf;
402}
403
404static ssize_t write_port(struct file *file, const char __user *buf,
405 size_t count, loff_t *ppos)
406{
407 unsigned long i = *ppos;
408 const char __user *tmp = buf;
409
410 if (!access_ok(buf, count))
411 return -EFAULT;
412 while (count-- > 0 && i < 65536) {
413 char c;
414
415 if (__get_user(c, tmp)) {
416 if (tmp > buf)
417 break;
418 return -EFAULT;
419 }
420 outb(c, i);
421 i++;
422 tmp++;
423 }
424 *ppos = i;
425 return tmp-buf;
426}
427
428static ssize_t read_null(struct file *file, char __user *buf,
429 size_t count, loff_t *ppos)
430{
431 return 0;
432}
433
434static ssize_t write_null(struct file *file, const char __user *buf,
435 size_t count, loff_t *ppos)
436{
437 return count;
438}
439
440static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
441{
442 return 0;
443}
444
445static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
446{
447 size_t count = iov_iter_count(from);
448 iov_iter_advance(from, count);
449 return count;
450}
451
452static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
453 struct splice_desc *sd)
454{
455 return sd->len;
456}
457
458static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
459 loff_t *ppos, size_t len, unsigned int flags)
460{
461 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
462}
463
464static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
465{
466 return 0;
467}
468
469static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
470{
471 size_t written = 0;
472
473 while (iov_iter_count(iter)) {
474 size_t chunk = iov_iter_count(iter), n;
475
476 if (chunk > PAGE_SIZE)
477 chunk = PAGE_SIZE; /* Just for latency reasons */
478 n = iov_iter_zero(chunk, iter);
479 if (!n && iov_iter_count(iter))
480 return written ? written : -EFAULT;
481 written += n;
482 if (signal_pending(current))
483 return written ? written : -ERESTARTSYS;
484 if (!need_resched())
485 continue;
486 if (iocb->ki_flags & IOCB_NOWAIT)
487 return written ? written : -EAGAIN;
488 cond_resched();
489 }
490 return written;
491}
492
493static ssize_t read_zero(struct file *file, char __user *buf,
494 size_t count, loff_t *ppos)
495{
496 size_t cleared = 0;
497
498 while (count) {
499 size_t chunk = min_t(size_t, count, PAGE_SIZE);
500 size_t left;
501
502 left = clear_user(buf + cleared, chunk);
503 if (unlikely(left)) {
504 cleared += (chunk - left);
505 if (!cleared)
506 return -EFAULT;
507 break;
508 }
509 cleared += chunk;
510 count -= chunk;
511
512 if (signal_pending(current))
513 break;
514 cond_resched();
515 }
516
517 return cleared;
518}
519
520static int mmap_zero(struct file *file, struct vm_area_struct *vma)
521{
522#ifndef CONFIG_MMU
523 return -ENOSYS;
524#endif
525 if (vma->vm_flags & VM_SHARED)
526 return shmem_zero_setup(vma);
527 vma_set_anonymous(vma);
528 return 0;
529}
530
531static unsigned long get_unmapped_area_zero(struct file *file,
532 unsigned long addr, unsigned long len,
533 unsigned long pgoff, unsigned long flags)
534{
535#ifdef CONFIG_MMU
536 if (flags & MAP_SHARED) {
537 /*
538 * mmap_zero() will call shmem_zero_setup() to create a file,
539 * so use shmem's get_unmapped_area in case it can be huge;
540 * and pass NULL for file as in mmap.c's get_unmapped_area(),
541 * so as not to confuse shmem with our handle on "/dev/zero".
542 */
543 return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags);
544 }
545
546 /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */
547 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
548#else
549 return -ENOSYS;
550#endif
551}
552
553static ssize_t write_full(struct file *file, const char __user *buf,
554 size_t count, loff_t *ppos)
555{
556 return -ENOSPC;
557}
558
559/*
560 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
561 * can fopen() both devices with "a" now. This was previously impossible.
562 * -- SRB.
563 */
564static loff_t null_lseek(struct file *file, loff_t offset, int orig)
565{
566 return file->f_pos = 0;
567}
568
569/*
570 * The memory devices use the full 32/64 bits of the offset, and so we cannot
571 * check against negative addresses: they are ok. The return value is weird,
572 * though, in that case (0).
573 *
574 * also note that seeking relative to the "end of file" isn't supported:
575 * it has no meaning, so it returns -EINVAL.
576 */
577static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
578{
579 loff_t ret;
580
581 inode_lock(file_inode(file));
582 switch (orig) {
583 case SEEK_CUR:
584 offset += file->f_pos;
585 fallthrough;
586 case SEEK_SET:
587 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
588 if ((unsigned long long)offset >= -MAX_ERRNO) {
589 ret = -EOVERFLOW;
590 break;
591 }
592 file->f_pos = offset;
593 ret = file->f_pos;
594 force_successful_syscall_return();
595 break;
596 default:
597 ret = -EINVAL;
598 }
599 inode_unlock(file_inode(file));
600 return ret;
601}
602
603static int open_port(struct inode *inode, struct file *filp)
604{
605 int rc;
606
607 if (!capable(CAP_SYS_RAWIO))
608 return -EPERM;
609
610 rc = security_locked_down(LOCKDOWN_DEV_MEM);
611 if (rc)
612 return rc;
613
614 if (iminor(inode) != DEVMEM_MINOR)
615 return 0;
616
617 /*
618 * Use a unified address space to have a single point to manage
619 * revocations when drivers want to take over a /dev/mem mapped
620 * range.
621 */
622 filp->f_mapping = iomem_get_mapping();
623
624 return 0;
625}
626
627#define zero_lseek null_lseek
628#define full_lseek null_lseek
629#define write_zero write_null
630#define write_iter_zero write_iter_null
631#define splice_write_zero splice_write_null
632#define open_mem open_port
633
634static const struct file_operations __maybe_unused mem_fops = {
635 .llseek = memory_lseek,
636 .read = read_mem,
637 .write = write_mem,
638 .mmap = mmap_mem,
639 .open = open_mem,
640#ifndef CONFIG_MMU
641 .get_unmapped_area = get_unmapped_area_mem,
642 .mmap_capabilities = memory_mmap_capabilities,
643#endif
644};
645
646static const struct file_operations null_fops = {
647 .llseek = null_lseek,
648 .read = read_null,
649 .write = write_null,
650 .read_iter = read_iter_null,
651 .write_iter = write_iter_null,
652 .splice_write = splice_write_null,
653 .uring_cmd = uring_cmd_null,
654};
655
656static const struct file_operations __maybe_unused port_fops = {
657 .llseek = memory_lseek,
658 .read = read_port,
659 .write = write_port,
660 .open = open_port,
661};
662
663static const struct file_operations zero_fops = {
664 .llseek = zero_lseek,
665 .write = write_zero,
666 .read_iter = read_iter_zero,
667 .read = read_zero,
668 .write_iter = write_iter_zero,
669 .splice_read = copy_splice_read,
670 .splice_write = splice_write_zero,
671 .mmap = mmap_zero,
672 .get_unmapped_area = get_unmapped_area_zero,
673#ifndef CONFIG_MMU
674 .mmap_capabilities = zero_mmap_capabilities,
675#endif
676};
677
678static const struct file_operations full_fops = {
679 .llseek = full_lseek,
680 .read_iter = read_iter_zero,
681 .write = write_full,
682 .splice_read = copy_splice_read,
683};
684
685static const struct memdev {
686 const char *name;
687 const struct file_operations *fops;
688 fmode_t fmode;
689 umode_t mode;
690} devlist[] = {
691#ifdef CONFIG_DEVMEM
692 [DEVMEM_MINOR] = { "mem", &mem_fops, FMODE_UNSIGNED_OFFSET, 0 },
693#endif
694 [3] = { "null", &null_fops, FMODE_NOWAIT, 0666 },
695#ifdef CONFIG_DEVPORT
696 [4] = { "port", &port_fops, 0, 0 },
697#endif
698 [5] = { "zero", &zero_fops, FMODE_NOWAIT, 0666 },
699 [7] = { "full", &full_fops, 0, 0666 },
700 [8] = { "random", &random_fops, FMODE_NOWAIT, 0666 },
701 [9] = { "urandom", &urandom_fops, FMODE_NOWAIT, 0666 },
702#ifdef CONFIG_PRINTK
703 [11] = { "kmsg", &kmsg_fops, 0, 0644 },
704#endif
705};
706
707static int memory_open(struct inode *inode, struct file *filp)
708{
709 int minor;
710 const struct memdev *dev;
711
712 minor = iminor(inode);
713 if (minor >= ARRAY_SIZE(devlist))
714 return -ENXIO;
715
716 dev = &devlist[minor];
717 if (!dev->fops)
718 return -ENXIO;
719
720 filp->f_op = dev->fops;
721 filp->f_mode |= dev->fmode;
722
723 if (dev->fops->open)
724 return dev->fops->open(inode, filp);
725
726 return 0;
727}
728
729static const struct file_operations memory_fops = {
730 .open = memory_open,
731 .llseek = noop_llseek,
732};
733
734static char *mem_devnode(const struct device *dev, umode_t *mode)
735{
736 if (mode && devlist[MINOR(dev->devt)].mode)
737 *mode = devlist[MINOR(dev->devt)].mode;
738 return NULL;
739}
740
741static const struct class mem_class = {
742 .name = "mem",
743 .devnode = mem_devnode,
744};
745
746static int __init chr_dev_init(void)
747{
748 int retval;
749 int minor;
750
751 if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
752 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
753
754 retval = class_register(&mem_class);
755 if (retval)
756 return retval;
757
758 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
759 if (!devlist[minor].name)
760 continue;
761
762 /*
763 * Create /dev/port?
764 */
765 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
766 continue;
767
768 device_create(&mem_class, NULL, MKDEV(MEM_MAJOR, minor),
769 NULL, devlist[minor].name);
770 }
771
772 return tty_init();
773}
774
775fs_initcall(chr_dev_init);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/drivers/char/mem.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * Added devfs support.
8 * Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
9 * Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
10 */
11
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#define DEVMEM_MINOR 1
35#define DEVPORT_MINOR 4
36
37static inline unsigned long size_inside_page(unsigned long start,
38 unsigned long size)
39{
40 unsigned long sz;
41
42 sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
43
44 return min(sz, size);
45}
46
47#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
48static inline int valid_phys_addr_range(phys_addr_t addr, size_t count)
49{
50 return addr + count <= __pa(high_memory);
51}
52
53static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
54{
55 return 1;
56}
57#endif
58
59#ifdef CONFIG_STRICT_DEVMEM
60static inline int page_is_allowed(unsigned long pfn)
61{
62 return devmem_is_allowed(pfn);
63}
64static inline int range_is_allowed(unsigned long pfn, unsigned long size)
65{
66 u64 from = ((u64)pfn) << PAGE_SHIFT;
67 u64 to = from + size;
68 u64 cursor = from;
69
70 while (cursor < to) {
71 if (!devmem_is_allowed(pfn))
72 return 0;
73 cursor += PAGE_SIZE;
74 pfn++;
75 }
76 return 1;
77}
78#else
79static inline int page_is_allowed(unsigned long pfn)
80{
81 return 1;
82}
83static inline int range_is_allowed(unsigned long pfn, unsigned long size)
84{
85 return 1;
86}
87#endif
88
89static inline bool should_stop_iteration(void)
90{
91 if (need_resched())
92 cond_resched();
93 return signal_pending(current);
94}
95
96/*
97 * This funcion reads the *physical* memory. The f_pos points directly to the
98 * memory location.
99 */
100static ssize_t read_mem(struct file *file, char __user *buf,
101 size_t count, loff_t *ppos)
102{
103 phys_addr_t p = *ppos;
104 ssize_t read, sz;
105 void *ptr;
106 char *bounce;
107 int err;
108
109 if (p != *ppos)
110 return 0;
111
112 if (!valid_phys_addr_range(p, count))
113 return -EFAULT;
114 read = 0;
115#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
116 /* we don't have page 0 mapped on sparc and m68k.. */
117 if (p < PAGE_SIZE) {
118 sz = size_inside_page(p, count);
119 if (sz > 0) {
120 if (clear_user(buf, sz))
121 return -EFAULT;
122 buf += sz;
123 p += sz;
124 count -= sz;
125 read += sz;
126 }
127 }
128#endif
129
130 bounce = kmalloc(PAGE_SIZE, GFP_KERNEL);
131 if (!bounce)
132 return -ENOMEM;
133
134 while (count > 0) {
135 unsigned long remaining;
136 int allowed, probe;
137
138 sz = size_inside_page(p, count);
139
140 err = -EPERM;
141 allowed = page_is_allowed(p >> PAGE_SHIFT);
142 if (!allowed)
143 goto failed;
144
145 err = -EFAULT;
146 if (allowed == 2) {
147 /* Show zeros for restricted memory. */
148 remaining = clear_user(buf, sz);
149 } else {
150 /*
151 * On ia64 if a page has been mapped somewhere as
152 * uncached, then it must also be accessed uncached
153 * by the kernel or data corruption may occur.
154 */
155 ptr = xlate_dev_mem_ptr(p);
156 if (!ptr)
157 goto failed;
158
159 probe = copy_from_kernel_nofault(bounce, ptr, sz);
160 unxlate_dev_mem_ptr(p, ptr);
161 if (probe)
162 goto failed;
163
164 remaining = copy_to_user(buf, bounce, sz);
165 }
166
167 if (remaining)
168 goto failed;
169
170 buf += sz;
171 p += sz;
172 count -= sz;
173 read += sz;
174 if (should_stop_iteration())
175 break;
176 }
177 kfree(bounce);
178
179 *ppos += read;
180 return read;
181
182failed:
183 kfree(bounce);
184 return err;
185}
186
187static ssize_t write_mem(struct file *file, const char __user *buf,
188 size_t count, loff_t *ppos)
189{
190 phys_addr_t p = *ppos;
191 ssize_t written, sz;
192 unsigned long copied;
193 void *ptr;
194
195 if (p != *ppos)
196 return -EFBIG;
197
198 if (!valid_phys_addr_range(p, count))
199 return -EFAULT;
200
201 written = 0;
202
203#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
204 /* we don't have page 0 mapped on sparc and m68k.. */
205 if (p < PAGE_SIZE) {
206 sz = size_inside_page(p, count);
207 /* Hmm. Do something? */
208 buf += sz;
209 p += sz;
210 count -= sz;
211 written += sz;
212 }
213#endif
214
215 while (count > 0) {
216 int allowed;
217
218 sz = size_inside_page(p, count);
219
220 allowed = page_is_allowed(p >> PAGE_SHIFT);
221 if (!allowed)
222 return -EPERM;
223
224 /* Skip actual writing when a page is marked as restricted. */
225 if (allowed == 1) {
226 /*
227 * On ia64 if a page has been mapped somewhere as
228 * uncached, then it must also be accessed uncached
229 * by the kernel or data corruption may occur.
230 */
231 ptr = xlate_dev_mem_ptr(p);
232 if (!ptr) {
233 if (written)
234 break;
235 return -EFAULT;
236 }
237
238 copied = copy_from_user(ptr, buf, sz);
239 unxlate_dev_mem_ptr(p, ptr);
240 if (copied) {
241 written += sz - copied;
242 if (written)
243 break;
244 return -EFAULT;
245 }
246 }
247
248 buf += sz;
249 p += sz;
250 count -= sz;
251 written += sz;
252 if (should_stop_iteration())
253 break;
254 }
255
256 *ppos += written;
257 return written;
258}
259
260int __weak phys_mem_access_prot_allowed(struct file *file,
261 unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
262{
263 return 1;
264}
265
266#ifndef __HAVE_PHYS_MEM_ACCESS_PROT
267
268/*
269 * Architectures vary in how they handle caching for addresses
270 * outside of main memory.
271 *
272 */
273#ifdef pgprot_noncached
274static int uncached_access(struct file *file, phys_addr_t addr)
275{
276 /*
277 * Accessing memory above the top the kernel knows about or through a
278 * file pointer
279 * that was marked O_DSYNC will be done non-cached.
280 */
281 if (file->f_flags & O_DSYNC)
282 return 1;
283 return addr >= __pa(high_memory);
284}
285#endif
286
287static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
288 unsigned long size, pgprot_t vma_prot)
289{
290#ifdef pgprot_noncached
291 phys_addr_t offset = pfn << PAGE_SHIFT;
292
293 if (uncached_access(file, offset))
294 return pgprot_noncached(vma_prot);
295#endif
296 return vma_prot;
297}
298#endif
299
300#ifndef CONFIG_MMU
301static unsigned long get_unmapped_area_mem(struct file *file,
302 unsigned long addr,
303 unsigned long len,
304 unsigned long pgoff,
305 unsigned long flags)
306{
307 if (!valid_mmap_phys_addr_range(pgoff, len))
308 return (unsigned long) -EINVAL;
309 return pgoff << PAGE_SHIFT;
310}
311
312/* permit direct mmap, for read, write or exec */
313static unsigned memory_mmap_capabilities(struct file *file)
314{
315 return NOMMU_MAP_DIRECT |
316 NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
317}
318
319static unsigned zero_mmap_capabilities(struct file *file)
320{
321 return NOMMU_MAP_COPY;
322}
323
324/* can't do an in-place private mapping if there's no MMU */
325static inline int private_mapping_ok(struct vm_area_struct *vma)
326{
327 return is_nommu_shared_mapping(vma->vm_flags);
328}
329#else
330
331static inline int private_mapping_ok(struct vm_area_struct *vma)
332{
333 return 1;
334}
335#endif
336
337static const struct vm_operations_struct mmap_mem_ops = {
338#ifdef CONFIG_HAVE_IOREMAP_PROT
339 .access = generic_access_phys
340#endif
341};
342
343static int mmap_mem(struct file *file, struct vm_area_struct *vma)
344{
345 size_t size = vma->vm_end - vma->vm_start;
346 phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
347
348 /* Does it even fit in phys_addr_t? */
349 if (offset >> PAGE_SHIFT != vma->vm_pgoff)
350 return -EINVAL;
351
352 /* It's illegal to wrap around the end of the physical address space. */
353 if (offset + (phys_addr_t)size - 1 < offset)
354 return -EINVAL;
355
356 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
357 return -EINVAL;
358
359 if (!private_mapping_ok(vma))
360 return -ENOSYS;
361
362 if (!range_is_allowed(vma->vm_pgoff, size))
363 return -EPERM;
364
365 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
366 &vma->vm_page_prot))
367 return -EINVAL;
368
369 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
370 size,
371 vma->vm_page_prot);
372
373 vma->vm_ops = &mmap_mem_ops;
374
375 /* Remap-pfn-range will mark the range VM_IO */
376 if (remap_pfn_range(vma,
377 vma->vm_start,
378 vma->vm_pgoff,
379 size,
380 vma->vm_page_prot)) {
381 return -EAGAIN;
382 }
383 return 0;
384}
385
386#ifdef CONFIG_DEVPORT
387static ssize_t read_port(struct file *file, char __user *buf,
388 size_t count, loff_t *ppos)
389{
390 unsigned long i = *ppos;
391 char __user *tmp = buf;
392
393 if (!access_ok(buf, count))
394 return -EFAULT;
395 while (count-- > 0 && i < 65536) {
396 if (__put_user(inb(i), tmp) < 0)
397 return -EFAULT;
398 i++;
399 tmp++;
400 }
401 *ppos = i;
402 return tmp-buf;
403}
404
405static ssize_t write_port(struct file *file, const char __user *buf,
406 size_t count, loff_t *ppos)
407{
408 unsigned long i = *ppos;
409 const char __user *tmp = buf;
410
411 if (!access_ok(buf, count))
412 return -EFAULT;
413 while (count-- > 0 && i < 65536) {
414 char c;
415
416 if (__get_user(c, tmp)) {
417 if (tmp > buf)
418 break;
419 return -EFAULT;
420 }
421 outb(c, i);
422 i++;
423 tmp++;
424 }
425 *ppos = i;
426 return tmp-buf;
427}
428#endif
429
430static ssize_t read_null(struct file *file, char __user *buf,
431 size_t count, loff_t *ppos)
432{
433 return 0;
434}
435
436static ssize_t write_null(struct file *file, const char __user *buf,
437 size_t count, loff_t *ppos)
438{
439 return count;
440}
441
442static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
443{
444 return 0;
445}
446
447static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
448{
449 size_t count = iov_iter_count(from);
450 iov_iter_advance(from, count);
451 return count;
452}
453
454static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
455 struct splice_desc *sd)
456{
457 return sd->len;
458}
459
460static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
461 loff_t *ppos, size_t len, unsigned int flags)
462{
463 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
464}
465
466static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
467{
468 return 0;
469}
470
471static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
472{
473 size_t written = 0;
474
475 while (iov_iter_count(iter)) {
476 size_t chunk = iov_iter_count(iter), n;
477
478 if (chunk > PAGE_SIZE)
479 chunk = PAGE_SIZE; /* Just for latency reasons */
480 n = iov_iter_zero(chunk, iter);
481 if (!n && iov_iter_count(iter))
482 return written ? written : -EFAULT;
483 written += n;
484 if (signal_pending(current))
485 return written ? written : -ERESTARTSYS;
486 if (!need_resched())
487 continue;
488 if (iocb->ki_flags & IOCB_NOWAIT)
489 return written ? written : -EAGAIN;
490 cond_resched();
491 }
492 return written;
493}
494
495static ssize_t read_zero(struct file *file, char __user *buf,
496 size_t count, loff_t *ppos)
497{
498 size_t cleared = 0;
499
500 while (count) {
501 size_t chunk = min_t(size_t, count, PAGE_SIZE);
502 size_t left;
503
504 left = clear_user(buf + cleared, chunk);
505 if (unlikely(left)) {
506 cleared += (chunk - left);
507 if (!cleared)
508 return -EFAULT;
509 break;
510 }
511 cleared += chunk;
512 count -= chunk;
513
514 if (signal_pending(current))
515 break;
516 cond_resched();
517 }
518
519 return cleared;
520}
521
522static int mmap_zero(struct file *file, struct vm_area_struct *vma)
523{
524#ifndef CONFIG_MMU
525 return -ENOSYS;
526#endif
527 if (vma->vm_flags & VM_SHARED)
528 return shmem_zero_setup(vma);
529 vma_set_anonymous(vma);
530 return 0;
531}
532
533static unsigned long get_unmapped_area_zero(struct file *file,
534 unsigned long addr, unsigned long len,
535 unsigned long pgoff, unsigned long flags)
536{
537#ifdef CONFIG_MMU
538 if (flags & MAP_SHARED) {
539 /*
540 * mmap_zero() will call shmem_zero_setup() to create a file,
541 * so use shmem's get_unmapped_area in case it can be huge;
542 * and pass NULL for file as in mmap.c's get_unmapped_area(),
543 * so as not to confuse shmem with our handle on "/dev/zero".
544 */
545 return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags);
546 }
547
548 /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */
549 return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
550#else
551 return -ENOSYS;
552#endif
553}
554
555static ssize_t write_full(struct file *file, const char __user *buf,
556 size_t count, loff_t *ppos)
557{
558 return -ENOSPC;
559}
560
561/*
562 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
563 * can fopen() both devices with "a" now. This was previously impossible.
564 * -- SRB.
565 */
566static loff_t null_lseek(struct file *file, loff_t offset, int orig)
567{
568 return file->f_pos = 0;
569}
570
571/*
572 * The memory devices use the full 32/64 bits of the offset, and so we cannot
573 * check against negative addresses: they are ok. The return value is weird,
574 * though, in that case (0).
575 *
576 * also note that seeking relative to the "end of file" isn't supported:
577 * it has no meaning, so it returns -EINVAL.
578 */
579static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
580{
581 loff_t ret;
582
583 inode_lock(file_inode(file));
584 switch (orig) {
585 case SEEK_CUR:
586 offset += file->f_pos;
587 fallthrough;
588 case SEEK_SET:
589 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
590 if ((unsigned long long)offset >= -MAX_ERRNO) {
591 ret = -EOVERFLOW;
592 break;
593 }
594 file->f_pos = offset;
595 ret = file->f_pos;
596 force_successful_syscall_return();
597 break;
598 default:
599 ret = -EINVAL;
600 }
601 inode_unlock(file_inode(file));
602 return ret;
603}
604
605static int open_port(struct inode *inode, struct file *filp)
606{
607 int rc;
608
609 if (!capable(CAP_SYS_RAWIO))
610 return -EPERM;
611
612 rc = security_locked_down(LOCKDOWN_DEV_MEM);
613 if (rc)
614 return rc;
615
616 if (iminor(inode) != DEVMEM_MINOR)
617 return 0;
618
619 /*
620 * Use a unified address space to have a single point to manage
621 * revocations when drivers want to take over a /dev/mem mapped
622 * range.
623 */
624 filp->f_mapping = iomem_get_mapping();
625
626 return 0;
627}
628
629#define zero_lseek null_lseek
630#define full_lseek null_lseek
631#define write_zero write_null
632#define write_iter_zero write_iter_null
633#define splice_write_zero splice_write_null
634#define open_mem open_port
635
636static const struct file_operations __maybe_unused mem_fops = {
637 .llseek = memory_lseek,
638 .read = read_mem,
639 .write = write_mem,
640 .mmap = mmap_mem,
641 .open = open_mem,
642#ifndef CONFIG_MMU
643 .get_unmapped_area = get_unmapped_area_mem,
644 .mmap_capabilities = memory_mmap_capabilities,
645#endif
646 .fop_flags = FOP_UNSIGNED_OFFSET,
647};
648
649static const struct file_operations null_fops = {
650 .llseek = null_lseek,
651 .read = read_null,
652 .write = write_null,
653 .read_iter = read_iter_null,
654 .write_iter = write_iter_null,
655 .splice_write = splice_write_null,
656 .uring_cmd = uring_cmd_null,
657};
658
659#ifdef CONFIG_DEVPORT
660static const struct file_operations port_fops = {
661 .llseek = memory_lseek,
662 .read = read_port,
663 .write = write_port,
664 .open = open_port,
665};
666#endif
667
668static const struct file_operations zero_fops = {
669 .llseek = zero_lseek,
670 .write = write_zero,
671 .read_iter = read_iter_zero,
672 .read = read_zero,
673 .write_iter = write_iter_zero,
674 .splice_read = copy_splice_read,
675 .splice_write = splice_write_zero,
676 .mmap = mmap_zero,
677 .get_unmapped_area = get_unmapped_area_zero,
678#ifndef CONFIG_MMU
679 .mmap_capabilities = zero_mmap_capabilities,
680#endif
681};
682
683static const struct file_operations full_fops = {
684 .llseek = full_lseek,
685 .read_iter = read_iter_zero,
686 .write = write_full,
687 .splice_read = copy_splice_read,
688};
689
690static const struct memdev {
691 const char *name;
692 const struct file_operations *fops;
693 fmode_t fmode;
694 umode_t mode;
695} devlist[] = {
696#ifdef CONFIG_DEVMEM
697 [DEVMEM_MINOR] = { "mem", &mem_fops, 0, 0 },
698#endif
699 [3] = { "null", &null_fops, FMODE_NOWAIT, 0666 },
700#ifdef CONFIG_DEVPORT
701 [4] = { "port", &port_fops, 0, 0 },
702#endif
703 [5] = { "zero", &zero_fops, FMODE_NOWAIT, 0666 },
704 [7] = { "full", &full_fops, 0, 0666 },
705 [8] = { "random", &random_fops, FMODE_NOWAIT, 0666 },
706 [9] = { "urandom", &urandom_fops, FMODE_NOWAIT, 0666 },
707#ifdef CONFIG_PRINTK
708 [11] = { "kmsg", &kmsg_fops, 0, 0644 },
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(const 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 const struct class mem_class = {
747 .name = "mem",
748 .devnode = mem_devnode,
749};
750
751static int __init chr_dev_init(void)
752{
753 int retval;
754 int minor;
755
756 if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
757 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
758
759 retval = class_register(&mem_class);
760 if (retval)
761 return retval;
762
763 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
764 if (!devlist[minor].name)
765 continue;
766
767 /*
768 * Create /dev/port?
769 */
770 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
771 continue;
772
773 device_create(&mem_class, NULL, MKDEV(MEM_MAJOR, minor),
774 NULL, devlist[minor].name);
775 }
776
777 return tty_init();
778}
779
780fs_initcall(chr_dev_init);