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![Kees Cook](/assets/img/avatar_default.png)
Under CONFIG_STRICT_DEVMEM, reading System RAM through /dev/mem is disallowed. However, on x86, the first 1MB was always allowed for BIOS and similar things, regardless of it actually being System RAM. It was possible for heap to end up getting allocated in low 1MB RAM, and then read by things like x86info or dd, which would trip hardened usercopy: usercopy: kernel memory exposure attempt detected from ffff880000090000 (dma-kmalloc-256) (4096 bytes) This changes the x86 exception for the low 1MB by reading back zeros for System RAM areas instead of blindly allowing them. More work is needed to extend this to mmap, but currently mmap doesn't go through usercopy, so hardened usercopy won't Oops the kernel. Reported-by: Tommi Rantala <tommi.t.rantala@nokia.com> Tested-by: Tommi Rantala <tommi.t.rantala@nokia.com> Signed-off-by: Kees Cook <keescook@chromium.org>
918 lines
20 KiB
C
918 lines
20 KiB
C
/*
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* linux/drivers/char/mem.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* Added devfs support.
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* Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
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* Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
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*/
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#include <linux/mm.h>
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#include <linux/miscdevice.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/mman.h>
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#include <linux/random.h>
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#include <linux/init.h>
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#include <linux/raw.h>
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#include <linux/tty.h>
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#include <linux/capability.h>
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#include <linux/ptrace.h>
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#include <linux/device.h>
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#include <linux/highmem.h>
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#include <linux/backing-dev.h>
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#include <linux/shmem_fs.h>
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#include <linux/splice.h>
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#include <linux/pfn.h>
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#include <linux/export.h>
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#include <linux/io.h>
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#include <linux/uio.h>
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#include <linux/uaccess.h>
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#ifdef CONFIG_IA64
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# include <linux/efi.h>
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#endif
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#define DEVPORT_MINOR 4
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static inline unsigned long size_inside_page(unsigned long start,
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unsigned long size)
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{
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unsigned long sz;
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sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
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return min(sz, size);
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}
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#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
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static inline int valid_phys_addr_range(phys_addr_t addr, size_t count)
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{
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return addr + count <= __pa(high_memory);
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}
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static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
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{
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return 1;
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}
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#endif
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#ifdef CONFIG_STRICT_DEVMEM
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static inline int page_is_allowed(unsigned long pfn)
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{
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return devmem_is_allowed(pfn);
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}
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static inline int range_is_allowed(unsigned long pfn, unsigned long size)
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{
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u64 from = ((u64)pfn) << PAGE_SHIFT;
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u64 to = from + size;
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u64 cursor = from;
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while (cursor < to) {
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if (!devmem_is_allowed(pfn))
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return 0;
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cursor += PAGE_SIZE;
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pfn++;
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}
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return 1;
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}
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#else
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static inline int page_is_allowed(unsigned long pfn)
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{
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return 1;
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}
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static inline int range_is_allowed(unsigned long pfn, unsigned long size)
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{
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return 1;
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}
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#endif
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#ifndef unxlate_dev_mem_ptr
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#define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
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void __weak unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
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{
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}
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#endif
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/*
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* This funcion reads the *physical* memory. The f_pos points directly to the
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* memory location.
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*/
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static ssize_t read_mem(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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phys_addr_t p = *ppos;
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ssize_t read, sz;
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void *ptr;
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if (p != *ppos)
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return 0;
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if (!valid_phys_addr_range(p, count))
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return -EFAULT;
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read = 0;
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#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
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/* we don't have page 0 mapped on sparc and m68k.. */
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if (p < PAGE_SIZE) {
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sz = size_inside_page(p, count);
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if (sz > 0) {
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if (clear_user(buf, sz))
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return -EFAULT;
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buf += sz;
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p += sz;
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count -= sz;
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read += sz;
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}
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}
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#endif
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while (count > 0) {
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unsigned long remaining;
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int allowed;
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sz = size_inside_page(p, count);
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allowed = page_is_allowed(p >> PAGE_SHIFT);
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if (!allowed)
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return -EPERM;
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if (allowed == 2) {
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/* Show zeros for restricted memory. */
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remaining = clear_user(buf, sz);
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} else {
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/*
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* On ia64 if a page has been mapped somewhere as
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* uncached, then it must also be accessed uncached
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* by the kernel or data corruption may occur.
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*/
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ptr = xlate_dev_mem_ptr(p);
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if (!ptr)
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return -EFAULT;
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remaining = copy_to_user(buf, ptr, sz);
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unxlate_dev_mem_ptr(p, ptr);
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}
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if (remaining)
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return -EFAULT;
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buf += sz;
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p += sz;
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count -= sz;
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read += sz;
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}
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*ppos += read;
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return read;
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}
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static ssize_t write_mem(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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phys_addr_t p = *ppos;
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ssize_t written, sz;
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unsigned long copied;
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void *ptr;
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if (p != *ppos)
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return -EFBIG;
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if (!valid_phys_addr_range(p, count))
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return -EFAULT;
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written = 0;
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#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
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/* we don't have page 0 mapped on sparc and m68k.. */
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if (p < PAGE_SIZE) {
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sz = size_inside_page(p, count);
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/* Hmm. Do something? */
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buf += sz;
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p += sz;
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count -= sz;
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written += sz;
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}
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#endif
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while (count > 0) {
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int allowed;
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sz = size_inside_page(p, count);
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allowed = page_is_allowed(p >> PAGE_SHIFT);
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if (!allowed)
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return -EPERM;
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/* Skip actual writing when a page is marked as restricted. */
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if (allowed == 1) {
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/*
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* On ia64 if a page has been mapped somewhere as
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* uncached, then it must also be accessed uncached
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* by the kernel or data corruption may occur.
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*/
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ptr = xlate_dev_mem_ptr(p);
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if (!ptr) {
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if (written)
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break;
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return -EFAULT;
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}
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copied = copy_from_user(ptr, buf, sz);
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unxlate_dev_mem_ptr(p, ptr);
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if (copied) {
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written += sz - copied;
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if (written)
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break;
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return -EFAULT;
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}
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}
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buf += sz;
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p += sz;
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count -= sz;
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written += sz;
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}
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*ppos += written;
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return written;
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}
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int __weak phys_mem_access_prot_allowed(struct file *file,
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unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
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{
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return 1;
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}
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#ifndef __HAVE_PHYS_MEM_ACCESS_PROT
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/*
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* Architectures vary in how they handle caching for addresses
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* outside of main memory.
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*
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*/
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#ifdef pgprot_noncached
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static int uncached_access(struct file *file, phys_addr_t addr)
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{
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#if defined(CONFIG_IA64)
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/*
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* On ia64, we ignore O_DSYNC because we cannot tolerate memory
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* attribute aliases.
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*/
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return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
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#elif defined(CONFIG_MIPS)
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{
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extern int __uncached_access(struct file *file,
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unsigned long addr);
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return __uncached_access(file, addr);
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}
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#else
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/*
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* Accessing memory above the top the kernel knows about or through a
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* file pointer
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* that was marked O_DSYNC will be done non-cached.
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*/
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if (file->f_flags & O_DSYNC)
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return 1;
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return addr >= __pa(high_memory);
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#endif
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}
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#endif
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static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
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unsigned long size, pgprot_t vma_prot)
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{
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#ifdef pgprot_noncached
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phys_addr_t offset = pfn << PAGE_SHIFT;
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if (uncached_access(file, offset))
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return pgprot_noncached(vma_prot);
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#endif
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return vma_prot;
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}
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#endif
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#ifndef CONFIG_MMU
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static unsigned long get_unmapped_area_mem(struct file *file,
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unsigned long addr,
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unsigned long len,
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unsigned long pgoff,
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unsigned long flags)
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{
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if (!valid_mmap_phys_addr_range(pgoff, len))
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return (unsigned long) -EINVAL;
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return pgoff << PAGE_SHIFT;
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}
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/* permit direct mmap, for read, write or exec */
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static unsigned memory_mmap_capabilities(struct file *file)
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{
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return NOMMU_MAP_DIRECT |
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NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
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}
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static unsigned zero_mmap_capabilities(struct file *file)
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{
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return NOMMU_MAP_COPY;
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}
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/* can't do an in-place private mapping if there's no MMU */
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static inline int private_mapping_ok(struct vm_area_struct *vma)
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{
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return vma->vm_flags & VM_MAYSHARE;
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}
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#else
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static inline int private_mapping_ok(struct vm_area_struct *vma)
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{
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return 1;
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}
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#endif
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static const struct vm_operations_struct mmap_mem_ops = {
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#ifdef CONFIG_HAVE_IOREMAP_PROT
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.access = generic_access_phys
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#endif
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};
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static int mmap_mem(struct file *file, struct vm_area_struct *vma)
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{
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size_t size = vma->vm_end - vma->vm_start;
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if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
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return -EINVAL;
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if (!private_mapping_ok(vma))
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return -ENOSYS;
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if (!range_is_allowed(vma->vm_pgoff, size))
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return -EPERM;
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if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
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&vma->vm_page_prot))
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return -EINVAL;
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vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
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size,
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vma->vm_page_prot);
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vma->vm_ops = &mmap_mem_ops;
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/* Remap-pfn-range will mark the range VM_IO */
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if (remap_pfn_range(vma,
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vma->vm_start,
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vma->vm_pgoff,
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size,
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vma->vm_page_prot)) {
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return -EAGAIN;
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}
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return 0;
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}
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static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
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{
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unsigned long pfn;
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/* Turn a kernel-virtual address into a physical page frame */
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pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
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/*
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* RED-PEN: on some architectures there is more mapped memory than
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* available in mem_map which pfn_valid checks for. Perhaps should add a
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* new macro here.
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*
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* RED-PEN: vmalloc is not supported right now.
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*/
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if (!pfn_valid(pfn))
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return -EIO;
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vma->vm_pgoff = pfn;
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return mmap_mem(file, vma);
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}
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/*
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* This function reads the *virtual* memory as seen by the kernel.
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*/
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static ssize_t read_kmem(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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unsigned long p = *ppos;
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ssize_t low_count, read, sz;
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char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
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int err = 0;
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read = 0;
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if (p < (unsigned long) high_memory) {
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low_count = count;
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if (count > (unsigned long)high_memory - p)
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low_count = (unsigned long)high_memory - p;
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#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
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/* we don't have page 0 mapped on sparc and m68k.. */
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if (p < PAGE_SIZE && low_count > 0) {
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sz = size_inside_page(p, low_count);
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if (clear_user(buf, sz))
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return -EFAULT;
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buf += sz;
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p += sz;
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read += sz;
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low_count -= sz;
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count -= sz;
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}
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#endif
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while (low_count > 0) {
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sz = size_inside_page(p, low_count);
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|
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/*
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* On ia64 if a page has been mapped somewhere as
|
|
* uncached, then it must also be accessed uncached
|
|
* by the kernel or data corruption may occur
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|
*/
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kbuf = xlate_dev_kmem_ptr((void *)p);
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if (!virt_addr_valid(kbuf))
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return -ENXIO;
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if (copy_to_user(buf, kbuf, sz))
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return -EFAULT;
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buf += sz;
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p += sz;
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read += sz;
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low_count -= sz;
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count -= sz;
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}
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}
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if (count > 0) {
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kbuf = (char *)__get_free_page(GFP_KERNEL);
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if (!kbuf)
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return -ENOMEM;
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while (count > 0) {
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sz = size_inside_page(p, count);
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if (!is_vmalloc_or_module_addr((void *)p)) {
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err = -ENXIO;
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break;
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}
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sz = vread(kbuf, (char *)p, sz);
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if (!sz)
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break;
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if (copy_to_user(buf, kbuf, sz)) {
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err = -EFAULT;
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break;
|
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}
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count -= sz;
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buf += sz;
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read += sz;
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p += sz;
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}
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|
free_page((unsigned long)kbuf);
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}
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|
*ppos = p;
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return read ? read : err;
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}
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|
|
|
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static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
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|
size_t count, loff_t *ppos)
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|
{
|
|
ssize_t written, sz;
|
|
unsigned long copied;
|
|
|
|
written = 0;
|
|
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
|
|
/* we don't have page 0 mapped on sparc and m68k.. */
|
|
if (p < PAGE_SIZE) {
|
|
sz = size_inside_page(p, count);
|
|
/* Hmm. Do something? */
|
|
buf += sz;
|
|
p += sz;
|
|
count -= sz;
|
|
written += sz;
|
|
}
|
|
#endif
|
|
|
|
while (count > 0) {
|
|
void *ptr;
|
|
|
|
sz = size_inside_page(p, count);
|
|
|
|
/*
|
|
* On ia64 if a page has been mapped somewhere as uncached, then
|
|
* it must also be accessed uncached by the kernel or data
|
|
* corruption may occur.
|
|
*/
|
|
ptr = xlate_dev_kmem_ptr((void *)p);
|
|
if (!virt_addr_valid(ptr))
|
|
return -ENXIO;
|
|
|
|
copied = copy_from_user(ptr, buf, sz);
|
|
if (copied) {
|
|
written += sz - copied;
|
|
if (written)
|
|
break;
|
|
return -EFAULT;
|
|
}
|
|
buf += sz;
|
|
p += sz;
|
|
count -= sz;
|
|
written += sz;
|
|
}
|
|
|
|
*ppos += written;
|
|
return written;
|
|
}
|
|
|
|
/*
|
|
* This function writes to the *virtual* memory as seen by the kernel.
|
|
*/
|
|
static ssize_t write_kmem(struct file *file, const char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
unsigned long p = *ppos;
|
|
ssize_t wrote = 0;
|
|
ssize_t virtr = 0;
|
|
char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
|
|
int err = 0;
|
|
|
|
if (p < (unsigned long) high_memory) {
|
|
unsigned long to_write = min_t(unsigned long, count,
|
|
(unsigned long)high_memory - p);
|
|
wrote = do_write_kmem(p, buf, to_write, ppos);
|
|
if (wrote != to_write)
|
|
return wrote;
|
|
p += wrote;
|
|
buf += wrote;
|
|
count -= wrote;
|
|
}
|
|
|
|
if (count > 0) {
|
|
kbuf = (char *)__get_free_page(GFP_KERNEL);
|
|
if (!kbuf)
|
|
return wrote ? wrote : -ENOMEM;
|
|
while (count > 0) {
|
|
unsigned long sz = size_inside_page(p, count);
|
|
unsigned long n;
|
|
|
|
if (!is_vmalloc_or_module_addr((void *)p)) {
|
|
err = -ENXIO;
|
|
break;
|
|
}
|
|
n = copy_from_user(kbuf, buf, sz);
|
|
if (n) {
|
|
err = -EFAULT;
|
|
break;
|
|
}
|
|
vwrite(kbuf, (char *)p, sz);
|
|
count -= sz;
|
|
buf += sz;
|
|
virtr += sz;
|
|
p += sz;
|
|
}
|
|
free_page((unsigned long)kbuf);
|
|
}
|
|
|
|
*ppos = p;
|
|
return virtr + wrote ? : err;
|
|
}
|
|
|
|
static ssize_t read_port(struct file *file, char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
unsigned long i = *ppos;
|
|
char __user *tmp = buf;
|
|
|
|
if (!access_ok(VERIFY_WRITE, buf, count))
|
|
return -EFAULT;
|
|
while (count-- > 0 && i < 65536) {
|
|
if (__put_user(inb(i), tmp) < 0)
|
|
return -EFAULT;
|
|
i++;
|
|
tmp++;
|
|
}
|
|
*ppos = i;
|
|
return tmp-buf;
|
|
}
|
|
|
|
static ssize_t write_port(struct file *file, const char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
unsigned long i = *ppos;
|
|
const char __user *tmp = buf;
|
|
|
|
if (!access_ok(VERIFY_READ, buf, count))
|
|
return -EFAULT;
|
|
while (count-- > 0 && i < 65536) {
|
|
char c;
|
|
|
|
if (__get_user(c, tmp)) {
|
|
if (tmp > buf)
|
|
break;
|
|
return -EFAULT;
|
|
}
|
|
outb(c, i);
|
|
i++;
|
|
tmp++;
|
|
}
|
|
*ppos = i;
|
|
return tmp-buf;
|
|
}
|
|
|
|
static ssize_t read_null(struct file *file, char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t write_null(struct file *file, const char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
return count;
|
|
}
|
|
|
|
static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
|
|
{
|
|
size_t count = iov_iter_count(from);
|
|
iov_iter_advance(from, count);
|
|
return count;
|
|
}
|
|
|
|
static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
|
|
struct splice_desc *sd)
|
|
{
|
|
return sd->len;
|
|
}
|
|
|
|
static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags)
|
|
{
|
|
return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
|
|
}
|
|
|
|
static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
|
|
{
|
|
size_t written = 0;
|
|
|
|
while (iov_iter_count(iter)) {
|
|
size_t chunk = iov_iter_count(iter), n;
|
|
|
|
if (chunk > PAGE_SIZE)
|
|
chunk = PAGE_SIZE; /* Just for latency reasons */
|
|
n = iov_iter_zero(chunk, iter);
|
|
if (!n && iov_iter_count(iter))
|
|
return written ? written : -EFAULT;
|
|
written += n;
|
|
if (signal_pending(current))
|
|
return written ? written : -ERESTARTSYS;
|
|
cond_resched();
|
|
}
|
|
return written;
|
|
}
|
|
|
|
static int mmap_zero(struct file *file, struct vm_area_struct *vma)
|
|
{
|
|
#ifndef CONFIG_MMU
|
|
return -ENOSYS;
|
|
#endif
|
|
if (vma->vm_flags & VM_SHARED)
|
|
return shmem_zero_setup(vma);
|
|
return 0;
|
|
}
|
|
|
|
static unsigned long get_unmapped_area_zero(struct file *file,
|
|
unsigned long addr, unsigned long len,
|
|
unsigned long pgoff, unsigned long flags)
|
|
{
|
|
#ifdef CONFIG_MMU
|
|
if (flags & MAP_SHARED) {
|
|
/*
|
|
* mmap_zero() will call shmem_zero_setup() to create a file,
|
|
* so use shmem's get_unmapped_area in case it can be huge;
|
|
* and pass NULL for file as in mmap.c's get_unmapped_area(),
|
|
* so as not to confuse shmem with our handle on "/dev/zero".
|
|
*/
|
|
return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags);
|
|
}
|
|
|
|
/* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */
|
|
return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
|
|
#else
|
|
return -ENOSYS;
|
|
#endif
|
|
}
|
|
|
|
static ssize_t write_full(struct file *file, const char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
return -ENOSPC;
|
|
}
|
|
|
|
/*
|
|
* Special lseek() function for /dev/null and /dev/zero. Most notably, you
|
|
* can fopen() both devices with "a" now. This was previously impossible.
|
|
* -- SRB.
|
|
*/
|
|
static loff_t null_lseek(struct file *file, loff_t offset, int orig)
|
|
{
|
|
return file->f_pos = 0;
|
|
}
|
|
|
|
/*
|
|
* The memory devices use the full 32/64 bits of the offset, and so we cannot
|
|
* check against negative addresses: they are ok. The return value is weird,
|
|
* though, in that case (0).
|
|
*
|
|
* also note that seeking relative to the "end of file" isn't supported:
|
|
* it has no meaning, so it returns -EINVAL.
|
|
*/
|
|
static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
|
|
{
|
|
loff_t ret;
|
|
|
|
inode_lock(file_inode(file));
|
|
switch (orig) {
|
|
case SEEK_CUR:
|
|
offset += file->f_pos;
|
|
case SEEK_SET:
|
|
/* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
|
|
if ((unsigned long long)offset >= -MAX_ERRNO) {
|
|
ret = -EOVERFLOW;
|
|
break;
|
|
}
|
|
file->f_pos = offset;
|
|
ret = file->f_pos;
|
|
force_successful_syscall_return();
|
|
break;
|
|
default:
|
|
ret = -EINVAL;
|
|
}
|
|
inode_unlock(file_inode(file));
|
|
return ret;
|
|
}
|
|
|
|
static int open_port(struct inode *inode, struct file *filp)
|
|
{
|
|
return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
|
|
}
|
|
|
|
#define zero_lseek null_lseek
|
|
#define full_lseek null_lseek
|
|
#define write_zero write_null
|
|
#define write_iter_zero write_iter_null
|
|
#define open_mem open_port
|
|
#define open_kmem open_mem
|
|
|
|
static const struct file_operations __maybe_unused mem_fops = {
|
|
.llseek = memory_lseek,
|
|
.read = read_mem,
|
|
.write = write_mem,
|
|
.mmap = mmap_mem,
|
|
.open = open_mem,
|
|
#ifndef CONFIG_MMU
|
|
.get_unmapped_area = get_unmapped_area_mem,
|
|
.mmap_capabilities = memory_mmap_capabilities,
|
|
#endif
|
|
};
|
|
|
|
static const struct file_operations __maybe_unused kmem_fops = {
|
|
.llseek = memory_lseek,
|
|
.read = read_kmem,
|
|
.write = write_kmem,
|
|
.mmap = mmap_kmem,
|
|
.open = open_kmem,
|
|
#ifndef CONFIG_MMU
|
|
.get_unmapped_area = get_unmapped_area_mem,
|
|
.mmap_capabilities = memory_mmap_capabilities,
|
|
#endif
|
|
};
|
|
|
|
static const struct file_operations null_fops = {
|
|
.llseek = null_lseek,
|
|
.read = read_null,
|
|
.write = write_null,
|
|
.read_iter = read_iter_null,
|
|
.write_iter = write_iter_null,
|
|
.splice_write = splice_write_null,
|
|
};
|
|
|
|
static const struct file_operations __maybe_unused port_fops = {
|
|
.llseek = memory_lseek,
|
|
.read = read_port,
|
|
.write = write_port,
|
|
.open = open_port,
|
|
};
|
|
|
|
static const struct file_operations zero_fops = {
|
|
.llseek = zero_lseek,
|
|
.write = write_zero,
|
|
.read_iter = read_iter_zero,
|
|
.write_iter = write_iter_zero,
|
|
.mmap = mmap_zero,
|
|
.get_unmapped_area = get_unmapped_area_zero,
|
|
#ifndef CONFIG_MMU
|
|
.mmap_capabilities = zero_mmap_capabilities,
|
|
#endif
|
|
};
|
|
|
|
static const struct file_operations full_fops = {
|
|
.llseek = full_lseek,
|
|
.read_iter = read_iter_zero,
|
|
.write = write_full,
|
|
};
|
|
|
|
static const struct memdev {
|
|
const char *name;
|
|
umode_t mode;
|
|
const struct file_operations *fops;
|
|
fmode_t fmode;
|
|
} devlist[] = {
|
|
#ifdef CONFIG_DEVMEM
|
|
[1] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET },
|
|
#endif
|
|
#ifdef CONFIG_DEVKMEM
|
|
[2] = { "kmem", 0, &kmem_fops, FMODE_UNSIGNED_OFFSET },
|
|
#endif
|
|
[3] = { "null", 0666, &null_fops, 0 },
|
|
#ifdef CONFIG_DEVPORT
|
|
[4] = { "port", 0, &port_fops, 0 },
|
|
#endif
|
|
[5] = { "zero", 0666, &zero_fops, 0 },
|
|
[7] = { "full", 0666, &full_fops, 0 },
|
|
[8] = { "random", 0666, &random_fops, 0 },
|
|
[9] = { "urandom", 0666, &urandom_fops, 0 },
|
|
#ifdef CONFIG_PRINTK
|
|
[11] = { "kmsg", 0644, &kmsg_fops, 0 },
|
|
#endif
|
|
};
|
|
|
|
static int memory_open(struct inode *inode, struct file *filp)
|
|
{
|
|
int minor;
|
|
const struct memdev *dev;
|
|
|
|
minor = iminor(inode);
|
|
if (minor >= ARRAY_SIZE(devlist))
|
|
return -ENXIO;
|
|
|
|
dev = &devlist[minor];
|
|
if (!dev->fops)
|
|
return -ENXIO;
|
|
|
|
filp->f_op = dev->fops;
|
|
filp->f_mode |= dev->fmode;
|
|
|
|
if (dev->fops->open)
|
|
return dev->fops->open(inode, filp);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct file_operations memory_fops = {
|
|
.open = memory_open,
|
|
.llseek = noop_llseek,
|
|
};
|
|
|
|
static char *mem_devnode(struct device *dev, umode_t *mode)
|
|
{
|
|
if (mode && devlist[MINOR(dev->devt)].mode)
|
|
*mode = devlist[MINOR(dev->devt)].mode;
|
|
return NULL;
|
|
}
|
|
|
|
static struct class *mem_class;
|
|
|
|
static int __init chr_dev_init(void)
|
|
{
|
|
int minor;
|
|
|
|
if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
|
|
printk("unable to get major %d for memory devs\n", MEM_MAJOR);
|
|
|
|
mem_class = class_create(THIS_MODULE, "mem");
|
|
if (IS_ERR(mem_class))
|
|
return PTR_ERR(mem_class);
|
|
|
|
mem_class->devnode = mem_devnode;
|
|
for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
|
|
if (!devlist[minor].name)
|
|
continue;
|
|
|
|
/*
|
|
* Create /dev/port?
|
|
*/
|
|
if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
|
|
continue;
|
|
|
|
device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
|
|
NULL, devlist[minor].name);
|
|
}
|
|
|
|
return tty_init();
|
|
}
|
|
|
|
fs_initcall(chr_dev_init);
|