[PATCH 1/4] powerpc/64s: implement probe_kernel_read/write without touching AMR
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2020-03-27 07:06:12
There is no need to allow user accesses when probing kernel addresses. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/include/asm/uaccess.h | 25 ++++++++++----- arch/powerpc/lib/Makefile | 2 +- arch/powerpc/lib/uaccess.c | 50 ++++++++++++++++++++++++++++++ 3 files changed, 68 insertions(+), 9 deletions(-) create mode 100644 arch/powerpc/lib/uaccess.c
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 2f500debae21..670910df3cc7 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h@@ -341,8 +341,8 @@ 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)) {
@@ -351,19 +351,19 @@ static inline unsigned long raw_copy_from_user(void *to, 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)
@@ -371,9 +371,18 @@ static inline unsigned long raw_copy_from_user(void *to, } barrier_nospec(); - allow_read_from_user(from, n); ret = __copy_tofrom_user((__force void __user *)to, from, n); - prevent_read_from_user(from, n); + return ret; +} + +static inline unsigned long +raw_copy_from_user(void *to, const void __user *from, unsigned long n) +{ + unsigned long ret; + + allow_read_from_user(to, n); + ret = raw_copy_from_user_allowed(to, from, n); + prevent_read_from_user(to, n); return ret; }
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index b8de3be10eb4..a15060b5008e 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile@@ -36,7 +36,7 @@ extra-$(CONFIG_PPC64) += crtsavres.o endif obj-$(CONFIG_PPC_BOOK3S_64) += copyuser_power7.o copypage_power7.o \ - memcpy_power7.o + memcpy_power7.o uaccess.o obj64-y += copypage_64.o copyuser_64.o mem_64.o hweight_64.o \ memcpy_64.o memcpy_mcsafe_64.o
diff --git a/arch/powerpc/lib/uaccess.c b/arch/powerpc/lib/uaccess.c
new file mode 100644
index 000000000000..0057ab52d6fe
--- /dev/null
+++ b/arch/powerpc/lib/uaccess.c@@ -0,0 +1,50 @@ +#include <linux/mm.h> +#include <linux/uaccess.h> + +static __always_inline long +probe_read_common(void *dst, const void __user *src, size_t size) +{ + long ret; + + pagefault_disable(); + ret = raw_copy_from_user_allowed(dst, src, size); + pagefault_enable(); + + return ret ? -EFAULT : 0; +} + +static __always_inline long +probe_write_common(void __user *dst, const void *src, size_t size) +{ + long ret; + + pagefault_disable(); + ret = raw_copy_to_user_allowed(dst, src, size); + pagefault_enable(); + + return ret ? -EFAULT : 0; +} + +long probe_kernel_read(void *dst, const void *src, size_t size) +{ + long ret; + mm_segment_t old_fs = get_fs(); + + set_fs(KERNEL_DS); + ret = probe_read_common(dst, (__force const void __user *)src, size); + set_fs(old_fs); + + return ret; +} + +long probe_kernel_write(void *dst, const void *src, size_t size) +{ + long ret; + mm_segment_t old_fs = get_fs(); + + set_fs(KERNEL_DS); + ret = probe_write_common((__force void __user *)dst, src, size); + set_fs(old_fs); + + return ret; +}
--
2.23.0