openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

powerpc/uaccess: Perform barrier_nospec() in KUAP allowance helpers 

barrier_nospec() in uaccess helpers is there to protect against
speculative accesses around access_ok().

When using user_access_begin() sequences together with
unsafe_get_user() like macros, barrier_nospec() is called for
every single read although we know the access_ok() is done
onece.

Since all user accesses must be granted by a call to either
allow_read_from_user() or allow_read_write_user() which will
always happen after the access_ok() check, move the barrier_nospec()
there.

Reported-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c72f014730823b413528e90ab6c4d3bcb79f8497.1612692067.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2021-02-07 10:08:11 +00:00 committed by Michael Ellerman
parent 22b89ba178
commit 8524e2e764
2 changed files with 3 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/powerpc/include/asm/kup.h
View File

@ -91,6 +91,7 @@ static __always_inline void setup_kup(void)
static inline void allow_read_from_user(const void __user *from, unsigned long size)
{
barrier_nospec();
allow_user_access(NULL, from, size, KUAP_READ);
}
@ -102,6 +103,7 @@ static inline void allow_write_to_user(void __user *to, unsigned long size)
static inline void allow_read_write_user(void __user *to, const void __user *from,
unsigned long size)
{
barrier_nospec();
allow_user_access(to, from, size, KUAP_READ_WRITE);
}

12
arch/powerpc/include/asm/uaccess.h
View File

@ -315,7 +315,6 @@ do { \
__chk_user_ptr(__gu_addr); \
if (!is_kernel_addr((unsigned long)__gu_addr)) \
might_fault(); \
barrier_nospec(); \
if (do_allow) \
__get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \
else \
@ -333,10 +332,8 @@ do { \
__typeof__(size) __gu_size = (size); \
\
might_fault(); \
if (access_ok(__gu_addr, __gu_size)) { \
barrier_nospec(); \
if (access_ok(__gu_addr, __gu_size)) \
__get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \
} \
(x) = (__force __typeof__(*(ptr)))__gu_val; \
\
__gu_err; \
@ -350,7 +347,6 @@ do { \
__typeof__(size) __gu_size = (size); \
\
__chk_user_ptr(__gu_addr); \
barrier_nospec(); \
__get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \
(x) = (__force __typeof__(*(ptr)))__gu_val; \
\
@ -395,7 +391,6 @@ raw_copy_in_user(void __user *to, const void __user *from, unsigned long n)
{
unsigned long ret;
barrier_nospec();
allow_read_write_user(to, from, n);
ret = __copy_tofrom_user(to, from, n);
prevent_read_write_user(to, from, n);
@ -412,19 +407,15 @@ static inline unsigned long raw_copy_from_user(void *to,
switch (n) {
case 1:
barrier_nospec();
__get_user_size(*(u8 *)to, from, 1, ret);
break;
case 2:
barrier_nospec();
__get_user_size(*(u16 *)to, from, 2, ret);
break;
case 4:
barrier_nospec();
__get_user_size(*(u32 *)to, from, 4, ret);
break;
case 8:
barrier_nospec();
__get_user_size(*(u64 *)to, from, 8, ret);
break;
}
@ -432,7 +423,6 @@ static inline unsigned long raw_copy_from_user(void *to,
return 0;
}
barrier_nospec();
allow_read_from_user(from, n);
ret = __copy_tofrom_user((__force void __user *)to, from, n);
prevent_read_from_user(from, n);