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x86, smap: Handle csum_partial_copy_*_user()

tip:x86/smap tip-bot for H. Peter Anvin 1 participant 1 message Sep 1, 2013 x86

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Commit-ID:  7263dda41b5a28ae6566fd126d9b06ada73dd721
Gitweb:     http://git.kernel.org/tip/7263dda41b5a28ae6566fd126d9b06ada73dd721
Author:     H. Peter Anvin <[email protected]>
AuthorDate: Fri, 30 Aug 2013 15:43:03 -0700
Committer:  H. Peter Anvin <[email protected]>
CommitDate: Sun, 1 Sep 2013 14:09:48 -0700

x86, smap: Handle csum_partial_copy_*_user()

Add SMAP annotations to csum_partial_copy_to/from_user(). These functions legitimately access user space and thus need to set the AC flag.

TODO: add explicit checks that the side with the kernel space pointer really points into kernel space.

Signed-off-by H. Peter Anvin <[email protected]>
Link http://lkml.kernel.org/n/[email protected] open here
Cc <[email protected]> # v3.7+
---
 arch/x86/include/asm/checksum_32.h | 22 +++++++++++++++++-----
 arch/x86/lib/csum-wrappers_64.c    | 12 ++++++++++--
 2 files changed, 27 insertions(+), 7 deletions(-)
arch/x86/include/asm/checksum_32.h +17 -5
index 46fc474..f50de69 100644
@@ -49,9 +49,15 @@ static inline __wsum csum_partial_copy_from_user(const void __user *src,
 						 int len, __wsum sum,
 						 int *err_ptr)
 {
+	__wsum ret;
+
 	might_sleep();
-	return csum_partial_copy_generic((__force void *)src, dst,
-					 len, sum, err_ptr, NULL);
+	stac();
+	ret = csum_partial_copy_generic((__force void *)src, dst,
+					len, sum, err_ptr, NULL);
+	clac();
+
+	return ret;
 }
 
 /*

@@ -176,10 +182,16 @@ static inline __wsum csum_and_copy_to_user(const void *src,
 					   int len, __wsum sum,
 					   int *err_ptr)
 {
+	__wsum ret;
+
 	might_sleep();
-	if (access_ok(VERIFY_WRITE, dst, len))
-		return csum_partial_copy_generic(src, (__force void *)dst,
-						 len, sum, NULL, err_ptr);
+	if (access_ok(VERIFY_WRITE, dst, len)) {
+		stac();
+		ret = csum_partial_copy_generic(src, (__force void *)dst,
+						len, sum, NULL, err_ptr);
+		clac();
+		return ret;
+	}
 
 	if (len)
 		*err_ptr = -EFAULT;
arch/x86/lib/csum-wrappers_64.c +10 -2
index 25b7ae8..7609e0e 100644
@@ -6,6 +6,7 @@
  */
 #include <asm/checksum.h>
 #include <linux/module.h>
+#include <asm/smap.h>
 
 /**
  * csum_partial_copy_from_user - Copy and checksum from user space.

@@ -52,8 +53,10 @@ csum_partial_copy_from_user(const void __user *src, void *dst,
 			len -= 2;
 		}
 	}
+	stac();
 	isum = csum_partial_copy_generic((__force const void *)src,
 				dst, len, isum, errp, NULL);
+	clac();
 	if (unlikely(*errp))
 		goto out_err;
 

@@ -82,6 +85,8 @@ __wsum
 csum_partial_copy_to_user(const void *src, void __user *dst,
 			  int len, __wsum isum, int *errp)
 {
+	__wsum ret;
+
 	might_sleep();
 
 	if (unlikely(!access_ok(VERIFY_WRITE, dst, len))) {

@@ -105,8 +110,11 @@ csum_partial_copy_to_user(const void *src, void __user *dst,
 	}
 
 	*errp = 0;
-	return csum_partial_copy_generic(src, (void __force *)dst,
-					 len, isum, NULL, errp);
+	stac();
+	ret = csum_partial_copy_generic(src, (void __force *)dst,
+					len, isum, NULL, errp);
+	clac();
+	return ret;
 }
 EXPORT_SYMBOL(csum_partial_copy_to_user);