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Message-Id: <ebcf8256e02a7dffb292f3d800e264dce263cac5.1585811416.git.christophe.leroy@c-s.fr>
Date: Thu, 2 Apr 2020 07:34:19 +0000 (UTC)
From: Christophe Leroy <christophe.leroy@....fr>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>, airlied@...ux.ie,
daniel@...ll.ch, torvalds@...ux-foundation.org,
viro@...iv.linux.org.uk, akpm@...ux-foundation.org,
keescook@...omium.org, hpa@...or.com
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-mm@...ck.org, linux-arch@...r.kernel.org
Subject: [PATCH RESEND 4/4] powerpc/uaccess: Implement user_read_access_begin and
user_write_access_begin
Add support for selective read or write user access with
user_read_access_begin/end and user_write_access_begin/end.
Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
arch/powerpc/include/asm/book3s/32/kup.h | 4 ++--
arch/powerpc/include/asm/kup.h | 14 +++++++++++++-
arch/powerpc/include/asm/uaccess.h | 22 ++++++++++++++++++++++
3 files changed, 37 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 3c0ba22dc360..1617e73bee30 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -108,7 +108,7 @@ static __always_inline void allow_user_access(void __user *to, const void __user
u32 addr, end;
BUILD_BUG_ON(!__builtin_constant_p(dir));
- BUILD_BUG_ON(dir == KUAP_CURRENT);
+ BUILD_BUG_ON(dir & ~KUAP_READ_WRITE);
if (!(dir & KUAP_WRITE))
return;
@@ -131,7 +131,7 @@ static __always_inline void prevent_user_access(void __user *to, const void __us
BUILD_BUG_ON(!__builtin_constant_p(dir));
- if (dir == KUAP_CURRENT) {
+ if (dir & KUAP_CURRENT_WRITE) {
u32 kuap = current->thread.kuap;
if (unlikely(!kuap))
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index 92bcd1a26d73..c745ee41ad66 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -10,7 +10,9 @@
* Use the current saved situation instead of the to/from/size params.
* Used on book3s/32
*/
-#define KUAP_CURRENT 4
+#define KUAP_CURRENT_READ 4
+#define KUAP_CURRENT_WRITE 8
+#define KUAP_CURRENT (KUAP_CURRENT_READ | KUAP_CURRENT_WRITE)
#ifdef CONFIG_PPC64
#include <asm/book3s/64/kup-radix.h>
@@ -101,6 +103,16 @@ static inline void prevent_current_access_user(void)
prevent_user_access(NULL, NULL, ~0UL, KUAP_CURRENT);
}
+static inline void prevent_current_read_from_user(void)
+{
+ prevent_user_access(NULL, NULL, ~0UL, KUAP_CURRENT_READ);
+}
+
+static inline void prevent_current_write_to_user(void)
+{
+ prevent_user_access(NULL, NULL, ~0UL, KUAP_CURRENT_WRITE);
+}
+
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_POWERPC_KUAP_H_ */
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 2f500debae21..4427d419eb1d 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -468,6 +468,28 @@ static __must_check inline bool user_access_begin(const void __user *ptr, size_t
#define user_access_save prevent_user_access_return
#define user_access_restore restore_user_access
+static __must_check inline bool
+user_read_access_begin(const void __user *ptr, size_t len)
+{
+ if (unlikely(!access_ok(ptr, len)))
+ return false;
+ allow_read_from_user(ptr, len);
+ return true;
+}
+#define user_read_access_begin user_read_access_begin
+#define user_read_access_end prevent_current_read_from_user
+
+static __must_check inline bool
+user_write_access_begin(const void __user *ptr, size_t len)
+{
+ if (unlikely(!access_ok(ptr, len)))
+ return false;
+ allow_write_to_user((void __user *)ptr, len);
+ return true;
+}
+#define user_write_access_begin user_write_access_begin
+#define user_write_access_end prevent_current_write_to_user
+
#define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0)
#define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
#define unsafe_put_user(x, p, e) unsafe_op_wrap(__put_user_allowed(x, p), e)
--
2.25.0
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