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Date: Wed, 04 Apr 2007 12:28:38 +1000
From: Rusty Russell <rusty@...tcorp.com.au>
To: lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] Expose range-checking functions from arch-specific
uaccess.h
lguest wants range checking, but unless there are other users I'm not
sure this is worth the pain. Putting it out there in case it's useful.
Cheers,
Rusty.
==
There are some places where we want to check if a value + length is
within a range. This can be tricky, so it's nice to have a single
routine.
Also, this can be done more efficiently (with arch-dependent) carry
bits, as shown by the __range_ok() implementation on several archs.
This patch exposes arch-specific "val_outside(val, len, limit)" and a
generic "range_within(start, len, base, limit)" function. As a
side-effect, it fixes the comment in i386/uaccess.h: __range_ok
doesn't test "(u33)addr + (u33)size >= (u33)current->addr_limit.seg",
it tests "(u33)addr + (u33)size > (u33)current->addr_limit.seg".
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
diff -r 4272a6d4f27c include/asm-generic/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-generic/range.h Wed Apr 04 12:18:15 2007 +1000
@@ -0,0 +1,20 @@
+#ifndef _ASM_GENERIC_RANGE_H
+#define _ASM_GENERIC_RANGE_H
+
+/**
+ * val_outside - is a value and length past a limit?
+ * @val: the start value
+ * @len: the length from the start
+ * @limit: the first invalid value
+ *
+ * Like val + len > limit, except with overflow checking.
+ */
+static inline bool val_outside(unsigned long val, unsigned long len,
+ unsigned long limit)
+
+{
+ return val + len > limit || val + len < val;
+}
+
+#endif /* _ASM_GENERIC_RANGE_H */
+
diff -r 4272a6d4f27c include/asm-i386/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-i386/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,14 @@
+#ifndef __ASM_RANGE_H
+#define __ASM_RANGE_H
+
+/* Is val + size > limit? This needs 33-bit arithmetic. We have a carry... */
+static inline bool val_outside(unsigned long val, unsigned long len,
+ unsigned long limit)
+{
+ unsigned long flag, roksum;
+ asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0"
+ :"=&r" (flag), "=r" (roksum)
+ :"1" (val), "g" (len), "rm" (limit));
+ return flag;
+}
+#endif /* __ASM_RANGE_H */
diff -r 4272a6d4f27c include/asm-i386/uaccess.h
--- a/include/asm-i386/uaccess.h Wed Apr 04 12:05:49 2007 +1000
+++ b/include/asm-i386/uaccess.h Wed Apr 04 12:14:45 2007 +1000
@@ -49,17 +49,12 @@ extern struct movsl_mask {
* Returns 0 if the range is valid, nonzero otherwise.
*
* This is equivalent to the following test:
- * (u33)addr + (u33)size >= (u33)current->addr_limit.seg
- *
- * This needs 33-bit arithmetic. We have a carry...
- */
-#define __range_ok(addr,size) ({ \
- unsigned long flag,roksum; \
- __chk_user_ptr(addr); \
- asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" \
- :"=&r" (flag), "=r" (roksum) \
- :"1" (addr),"g" ((int)(size)),"rm" (current_thread_info()->addr_limit.seg)); \
- flag; })
+ * (u33)addr + (u33)size > (u33)current->addr_limit.seg
+ */
+#define __range_ok(addr,size) ({ \
+ __chk_user_ptr(addr); \
+ val_outside((int)(addr),(size),current_thread_info()->addr_limit.seg); \
+})
/**
* access_ok: - Checks if a user space pointer is valid
diff -r 4272a6d4f27c include/linux/kernel.h
--- a/include/linux/kernel.h Wed Apr 04 12:05:49 2007 +1000
+++ b/include/linux/kernel.h Wed Apr 04 12:22:52 2007 +1000
@@ -16,6 +16,7 @@
#include <linux/log2.h>
#include <asm/byteorder.h>
#include <asm/bug.h>
+#include <asm/range.h>
extern const char linux_banner[];
extern const char linux_proc_banner[];
@@ -311,6 +312,26 @@ static inline int __attribute__ ((format
(void)__tmp; \
})
+/**
+ * range_within - is one range within another?
+ * @start: the start value
+ * @len: the length from the start
+ * @base: the first valid value
+ * @limit: the first invalid value
+ *
+ * This is usually used for memory range testing. The common cases of
+ * constant 0 start and constant 0 len cases are optimized out.
+ */
+static inline bool range_within(unsigned long start, unsigned long len,
+ unsigned long base, unsigned long limit)
+{
+ if (start < base)
+ return false;
+ if (__builtin_constant_p(len) && len == 0)
+ return start - base <= limit - base;
+ return !val_outside(limit, start, len);
+}
+
struct sysinfo;
extern int do_sysinfo(struct sysinfo *info);
diff -r 4272a6d4f27c include/asm-alpha/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-alpha/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-arm/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-arm/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-arm26/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-arm26/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-avr32/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-avr32/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-blackfin/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-blackfin/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-cris/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-cris/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-frv/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-frv/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-h8300/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-h8300/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-ia64/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-ia64/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-m32r/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-m32r/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-m68k/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-m68k/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-m68knommu/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-m68knommu/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-mips/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-mips/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-parisc/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-parisc/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-powerpc/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-powerpc/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-ppc/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-ppc/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-s390/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-s390/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-sh/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-sh/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-sh64/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-sh64/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-sparc/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-sparc/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-sparc64/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-sparc64/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-um/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-um/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-v850/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-v850/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-x86_64/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-x86_64/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
diff -r 4272a6d4f27c include/asm-xtensa/range.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-xtensa/range.h Wed Apr 04 12:14:45 2007 +1000
@@ -0,0 +1,6 @@
+#ifndef __ALPHA_RANGE_H
+#define __ALPHA_RANGE_H
+
+#include <asm-generic/range.h>
+
+#endif /* __ALPHA_RANGE_H */
-
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