admin/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2025-12-07 20:06:24 +00:00
Code Issues Packages Projects Releases Wiki Activity

s390/uaccess: add KMSAN support to put_user() and get_user()

Browse Source 
put_user() uses inline assembly with precise constraints, so Clang is in
principle capable of instrumenting it automatically.  Unfortunately, one
of the constraints contains a dereferenced user pointer, and Clang does
not currently distinguish user and kernel pointers.  Therefore KMSAN
attempts to access shadow for user pointers, which is not a right thing to
do.

An obvious fix to add __no_sanitize_memory to __put_user_fn() does not
work, since it's __always_inline.  And __always_inline cannot be removed
due to the __put_user_bad() trick.

A different obvious fix of using the "a" instead of the "+Q" constraint
degrades the code quality, which is very important here, since it's a hot
path.

Instead, repurpose the __put_user_asm() macro to define
__put_user_{char,short,int,long}_noinstr() functions and mark them with
__no_sanitize_memory.  For the non-KMSAN builds make them __always_inline
in order to keep the generated code quality.  Also define
__put_user_{char,short,int,long}() functions, which call the
aforementioned ones and which *are* instrumented, because they call KMSAN
hooks, which may be implemented as macros.

The same applies to get_user() as well.

Link: https://lkml.kernel.org/r/20240621113706.315500-35-iii@linux.ibm.com
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <kasan-dev@googlegroups.com>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ilya Leoshkevich
2024-06-21 13:35:18 +02:00
committed by Andrew Morton
parent c1057a707a
commit eb6efdfeae
1 changed files with 79 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files

111
arch/s390/include/asm/uaccess.h
View File

@@ -78,13 +78,24 @@ union oac {
int __noreturn __put_user_bad(void);
#define __put_user_asm(to, from, size) \
({ \
#ifdef CONFIG_KMSAN
#define get_put_user_noinstr_attributes \
noinline __maybe_unused __no_sanitize_memory
#else
#define get_put_user_noinstr_attributes __always_inline
#endif
#define DEFINE_PUT_USER(type) \
static get_put_user_noinstr_attributes int \
__put_user_##type##_noinstr(unsigned type __user *to, \
unsigned type *from, \
unsigned long size) \
{ \
union oac __oac_spec = { \
.oac1.as = PSW_BITS_AS_SECONDARY, \
.oac1.a = 1, \
}; \
int __rc; \
int rc; \
\
asm volatile( \
" lr 0,%[spec]\n" \
@@ -93,12 +104,28 @@ int __noreturn __put_user_bad(void);
"2:\n" \
EX_TABLE_UA_STORE(0b, 2b, %[rc]) \
EX_TABLE_UA_STORE(1b, 2b, %[rc]) \
: [rc] "=&d" (__rc), [_to] "+Q" (*(to)) \
: [rc] "=&d" (rc), [_to] "+Q" (*(to)) \
: [_size] "d" (size), [_from] "Q" (*(from)), \
[spec] "d" (__oac_spec.val) \
: "cc", "0"); \
__rc; \
})
return rc; \
} \
\
static __always_inline int \
__put_user_##type(unsigned type __user *to, unsigned type *from, \
unsigned long size) \
{ \
int rc; \
\
rc = __put_user_##type##_noinstr(to, from, size); \
instrument_put_user(*from, to, size); \
return rc; \
}
DEFINE_PUT_USER(char);
DEFINE_PUT_USER(short);
DEFINE_PUT_USER(int);
DEFINE_PUT_USER(long);
static __always_inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)
{
@@ -106,24 +133,24 @@ static __always_inline int __put_user_fn(void *x, void __user *ptr, unsigned lon
switch (size) {
case 1:
rc = __put_user_asm((unsigned char __user *)ptr,
(unsigned char *)x,
size);
rc = __put_user_char((unsigned char __user *)ptr,
(unsigned char *)x,
size);
break;
case 2:
rc = __put_user_asm((unsigned short __user *)ptr,
(unsigned short *)x,
size);
rc = __put_user_short((unsigned short __user *)ptr,
(unsigned short *)x,
size);
break;
case 4:
rc = __put_user_asm((unsigned int __user *)ptr,
rc = __put_user_int((unsigned int __user *)ptr,
(unsigned int *)x,
size);
break;
case 8:
rc = __put_user_asm((unsigned long __user *)ptr,
(unsigned long *)x,
size);
rc = __put_user_long((unsigned long __user *)ptr,
(unsigned long *)x,
size);
break;
default:
__put_user_bad();
@@ -134,13 +161,17 @@ static __always_inline int __put_user_fn(void *x, void __user *ptr, unsigned lon
int __noreturn __get_user_bad(void);
#define __get_user_asm(to, from, size) \
({ \
#define DEFINE_GET_USER(type) \
static get_put_user_noinstr_attributes int \
__get_user_##type##_noinstr(unsigned type *to, \
unsigned type __user *from, \
unsigned long size) \
{ \
union oac __oac_spec = { \
.oac2.as = PSW_BITS_AS_SECONDARY, \
.oac2.a = 1, \
}; \
int __rc; \
int rc; \
\
asm volatile( \
" lr 0,%[spec]\n" \
@@ -149,13 +180,29 @@ int __noreturn __get_user_bad(void);
"2:\n" \
EX_TABLE_UA_LOAD_MEM(0b, 2b, %[rc], %[_to], %[_ksize]) \
EX_TABLE_UA_LOAD_MEM(1b, 2b, %[rc], %[_to], %[_ksize]) \
: [rc] "=&d" (__rc), "=Q" (*(to)) \
: [rc] "=&d" (rc), "=Q" (*(to)) \
: [_size] "d" (size), [_from] "Q" (*(from)), \
[spec] "d" (__oac_spec.val), [_to] "a" (to), \
[_ksize] "K" (size) \
: "cc", "0"); \
__rc; \
})
return rc; \
} \
\
static __always_inline int \
__get_user_##type(unsigned type *to, unsigned type __user *from, \
unsigned long size) \
{ \
int rc; \
\
rc = __get_user_##type##_noinstr(to, from, size); \
instrument_get_user(*to); \
return rc; \
}
DEFINE_GET_USER(char);
DEFINE_GET_USER(short);
DEFINE_GET_USER(int);
DEFINE_GET_USER(long);
static __always_inline int __get_user_fn(void *x, const void __user *ptr, unsigned long size)
{
@@ -163,24 +210,24 @@ static __always_inline int __get_user_fn(void *x, const void __user *ptr, unsign
switch (size) {
case 1:
rc = __get_user_asm((unsigned char *)x,
(unsigned char __user *)ptr,
size);
rc = __get_user_char((unsigned char *)x,
(unsigned char __user *)ptr,
size);
break;
case 2:
rc = __get_user_asm((unsigned short *)x,
(unsigned short __user *)ptr,
size);
rc = __get_user_short((unsigned short *)x,
(unsigned short __user *)ptr,
size);
break;
case 4:
rc = __get_user_asm((unsigned int *)x,
rc = __get_user_int((unsigned int *)x,
(unsigned int __user *)ptr,
size);
break;
case 8:
rc = __get_user_asm((unsigned long *)x,
(unsigned long __user *)ptr,
size);
rc = __get_user_long((unsigned long *)x,
(unsigned long __user *)ptr,
size);
break;
default:
__get_user_bad();