Re: [PATCH v3 1/8] powerpc/uaccess: Add unsafe_copy_from_user
flat view
From: Christophe Leroy <hidden>
Date: 2021-01-11 13:27:38
Le 09/01/2021 à 04:25, Christopher M. Riedl a écrit :
Implement raw_copy_from_user_allowed() which assumes that userspace read access is open. Use this new function to implement raw_copy_from_user(). Finally, wrap the new function to follow the usual "unsafe_" convention of taking a label argument.
I think there is no point implementing raw_copy_from_user_allowed(), see https://github.com/linuxppc/linux/commit/4b842e4e25b1 and https://patchwork.ozlabs.org/project/linuxppc-dev/patch/8c74fc9ce8131cabb10b3e95dc0e430f396ee83e.1610369143.git.christophe.leroy@csgroup.eu/ You should simply do: #define unsafe_copy_from_user(d, s, l, e) \ unsafe_op_wrap(__copy_tofrom_user((__force void __user *)d, s, l), e) Christophe
quoted hunk ↗ jump to hunk
The new raw_copy_from_user_allowed() calls non-inline __copy_tofrom_user() internally. This is still safe to call inside user access blocks formed with user_*_access_begin()/user_*_access_end() since asm functions are not instrumented for tracing. Signed-off-by: Christopher M. Riedl <redacted> --- arch/powerpc/include/asm/uaccess.h | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-)diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index 501c9a79038c..698f3a6d6ae5 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h@@ -403,38 +403,45 @@ raw_copy_in_user(void __user *to, const void __user *from, unsigned long n) } #endif /* __powerpc64__ */ -static inline unsigned long raw_copy_from_user(void *to, - const void __user *from, unsigned long n) +static inline unsigned long +raw_copy_from_user_allowed(void *to, const void __user *from, unsigned long n) { - unsigned long ret; if (__builtin_constant_p(n) && (n <= 8)) { - ret = 1; + unsigned long ret = 1; switch (n) { case 1: barrier_nospec(); - __get_user_size(*(u8 *)to, from, 1, ret); + __get_user_size_allowed(*(u8 *)to, from, 1, ret); break; case 2: barrier_nospec(); - __get_user_size(*(u16 *)to, from, 2, ret); + __get_user_size_allowed(*(u16 *)to, from, 2, ret); break; case 4: barrier_nospec(); - __get_user_size(*(u32 *)to, from, 4, ret); + __get_user_size_allowed(*(u32 *)to, from, 4, ret); break; case 8: barrier_nospec(); - __get_user_size(*(u64 *)to, from, 8, ret); + __get_user_size_allowed(*(u64 *)to, from, 8, ret); break; } if (ret == 0) return 0; } + return __copy_tofrom_user((__force void __user *)to, from, n); +} + +static inline unsigned long +raw_copy_from_user(void *to, const void __user *from, unsigned long n) +{ + unsigned long ret; + barrier_nospec(); allow_read_from_user(from, n); - ret = __copy_tofrom_user((__force void __user *)to, from, n); + ret = raw_copy_from_user_allowed(to, from, n); prevent_read_from_user(from, n); return ret; }@@ -542,6 +549,9 @@ user_write_access_begin(const void __user *ptr, size_t len) #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e) #define unsafe_put_user(x, p, e) __put_user_goto(x, p, e) +#define unsafe_copy_from_user(d, s, l, e) \ + unsafe_op_wrap(raw_copy_from_user_allowed(d, s, l), e) + #define unsafe_copy_to_user(d, s, l, e) \ do { \ u8 __user *_dst = (u8 __user *)(d); \