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maccess: unify the probe kernel arch hooks 

Currently architectures have to override every routine that probes
kernel memory, which includes a pure read and strcpy, both in strict
and not strict variants.  Just provide a single arch hooks instead to
make sure all architectures cover all the cases.

[akpm@linux-foundation.org: fix !CONFIG_X86_64 build]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200521152301.2587579-11-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Hellwig 2020-06-08 21:34:27 -07:00 committed by Linus Torvalds
parent cd0309058f
commit eab0c6089b
5 changed files with 61 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
arch/parisc/lib/memcpy.c
View File

@ -57,14 +57,10 @@ void * memcpy(void * dst,const void *src, size_t count)
EXPORT_SYMBOL(raw_copy_in_user);
EXPORT_SYMBOL(memcpy);
long probe_kernel_read(void *dst, const void *src, size_t size)
bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict)
{
unsigned long addr = (unsigned long)src;
if (addr < PAGE_SIZE)
return -EFAULT;
if ((unsigned long)unsafe_src < PAGE_SIZE)
return false;
/* check for I/O space F_EXTEND(0xfff00000) access as well? */
return __probe_kernel_read(dst, src, size);
return true;
}

10
arch/um/kernel/maccess.c
View File

@ -7,15 +7,13 @@
#include <linux/kernel.h>
#include <os.h>
long probe_kernel_read(void *dst, const void *src, size_t size)
bool probe_kernel_read_allowed(const void *src, size_t size, bool strict)
{
void *psrc = (void *)rounddown((unsigned long)src, PAGE_SIZE);
if ((unsigned long)src < PAGE_SIZE || size <= 0)
return -EFAULT;
return false;
if (os_mincore(psrc, size + src - psrc) <= 0)
return -EFAULT;
return __probe_kernel_read(dst, src, size);
return false;
return true;
}

33
arch/x86/mm/maccess.c
View File

@ -9,35 +9,26 @@ static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits)
return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits);
}
static __always_inline bool invalid_probe_range(u64 vaddr)
bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict)
{
unsigned long vaddr = (unsigned long)unsafe_src;
if (!strict)
return true;
/*
* Range covering the highest possible canonical userspace address
* as well as non-canonical address range. For the canonical range
* we also need to include the userspace guard page.
*/
return vaddr < TASK_SIZE_MAX + PAGE_SIZE ||
canonical_address(vaddr, boot_cpu_data.x86_virt_bits) != vaddr;
return vaddr >= TASK_SIZE_MAX + PAGE_SIZE &&
canonical_address(vaddr, boot_cpu_data.x86_virt_bits) == vaddr;
}
#else
static __always_inline bool invalid_probe_range(u64 vaddr)
bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict)
{
return vaddr < TASK_SIZE_MAX;
if (!strict)
return true;
return (unsigned long)unsafe_src >= TASK_SIZE_MAX;
}
#endif
long probe_kernel_read_strict(void *dst, const void *src, size_t size)
{
if (unlikely(invalid_probe_range((unsigned long)src)))
return -EFAULT;
return __probe_kernel_read(dst, src, size);
}
long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
{
if (unlikely(invalid_probe_range((unsigned long)unsafe_addr)))
return -EFAULT;
return __strncpy_from_unsafe(dst, unsafe_addr, count);
}

6
include/linux/uaccess.h
View File

@ -301,9 +301,11 @@ copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
return 0;
}
bool probe_kernel_read_allowed(const void *unsafe_src, size_t size,
bool strict);
extern long probe_kernel_read(void *dst, const void *src, size_t size);
extern long probe_kernel_read_strict(void *dst, const void *src, size_t size);
extern long __probe_kernel_read(void *dst, const void *src, size_t size);
extern long probe_user_read(void *dst, const void __user *src, size_t size);
extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
@ -312,7 +314,7 @@ extern long notrace probe_user_write(void __user *dst, const void *src, size_t s
extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
long count);
extern long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
long count);
long strnlen_user_nofault(const void __user *unsafe_addr, long count);

50
mm/maccess.c
View File

@ -6,6 +6,17 @@
#include <linux/mm.h>
#include <linux/uaccess.h>
static long __probe_kernel_read(void *dst, const void *src, size_t size,
bool strict);
static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,
long count, bool strict);
bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size,
bool strict)
{
return true;
}
/**
* probe_kernel_read(): safely attempt to read from any location
* @dst: pointer to the buffer that shall take the data
@ -19,8 +30,11 @@
* DO NOT USE THIS FUNCTION - it is broken on architectures with entirely
* separate kernel and user address spaces, and also a bad idea otherwise.
*/
long __weak probe_kernel_read(void *dst, const void *src, size_t size)
__attribute__((alias("__probe_kernel_read")));
long probe_kernel_read(void *dst, const void *src, size_t size)
{
return __probe_kernel_read(dst, src, size, false);
}
EXPORT_SYMBOL_GPL(probe_kernel_read);
/**
* probe_kernel_read_strict(): safely attempt to read from kernel-space
@ -36,15 +50,20 @@ long __weak probe_kernel_read(void *dst, const void *src, size_t size)
* probe_kernel_read() suitable for use within regions where the caller
* already holds mmap_lock, or other locks which nest inside mmap_lock.
*/
long probe_kernel_read_strict(void *dst, const void *src, size_t size)
{
return __probe_kernel_read(dst, src, size, true);
}
long __weak probe_kernel_read_strict(void *dst, const void *src, size_t size)
__attribute__((alias("__probe_kernel_read")));
long __probe_kernel_read(void *dst, const void *src, size_t size)
static long __probe_kernel_read(void *dst, const void *src, size_t size,
bool strict)
{
long ret;
mm_segment_t old_fs = get_fs();
if (!probe_kernel_read_allowed(src, size, strict))
return -EFAULT;
set_fs(KERNEL_DS);
pagefault_disable();
ret = __copy_from_user_inatomic(dst, (__force const void __user *)src,
@ -56,7 +75,6 @@ long __probe_kernel_read(void *dst, const void *src, size_t size)
return -EFAULT;
return 0;
}
EXPORT_SYMBOL_GPL(probe_kernel_read);
/**
* probe_user_read(): safely attempt to read from a user-space location
@ -163,8 +181,10 @@ EXPORT_SYMBOL_GPL(probe_user_write);
* DO NOT USE THIS FUNCTION - it is broken on architectures with entirely
* separate kernel and user address spaces, and also a bad idea otherwise.
*/
long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
__attribute__((alias("__strncpy_from_unsafe")));
long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
{
return __strncpy_from_unsafe(dst, unsafe_addr, count, false);
}
/**
* strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe
@ -184,11 +204,13 @@ long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
* If @count is smaller than the length of the string, copies @count-1 bytes,
* sets the last byte of @dst buffer to NUL and returns @count.
*/
long __weak strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
long count)
__attribute__((alias("__strncpy_from_unsafe")));
long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
{
return __strncpy_from_unsafe(dst, unsafe_addr, count, true);
}
long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,
long count, bool strict)
{
mm_segment_t old_fs = get_fs();
const void *src = unsafe_addr;
@ -196,6 +218,8 @@ long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
if (unlikely(count <= 0))
return 0;
if (!probe_kernel_read_allowed(unsafe_addr, count, strict))
return -EFAULT;
set_fs(KERNEL_DS);
pagefault_disable();