Le 27/03/2020 à 08:02, Nicholas Piggin a écrit :
There is no need to allow user accesses when probing kernel addresses.
Signed-off-by: Nicholas Piggin <npig...@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/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
Why only book3s/64 ? It applies to the 8xx and book3s/32 as well, I
think it should just be for all powerpc.
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);
I think you should squash probe_read_common() here, having it separated
is a lot of lines for no added value. It also may make people believe it
overwrites the generic probe_read_common()
+ 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);
Same comment as for probe_read_common()
+ set_fs(old_fs);
+
+ return ret;
+}
Christophe
