[S390] uaccess: implement strict user copy checks
Same as on x86 and sparc, besides the fact that enabling the option will just emit compile time warnings instead of errors. Keeps allyesconfig kernels compiling. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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@ -6,4 +6,17 @@ config TRACE_IRQFLAGS_SUPPORT
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source "lib/Kconfig.debug"
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source "lib/Kconfig.debug"
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config DEBUG_STRICT_USER_COPY_CHECKS
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bool "Strict user copy size checks"
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---help---
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Enabling this option turns a certain set of sanity checks for user
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copy operations into compile time warnings.
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The copy_from_user() etc checks are there to help test if there
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are sufficient security checks on the length argument of
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the copy operation, by having gcc prove that the argument is
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within bounds.
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If unsure, or if you run an older (pre 4.4) gcc, say N.
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endmenu
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endmenu
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@ -265,6 +265,12 @@ __copy_from_user(void *to, const void __user *from, unsigned long n)
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return uaccess.copy_from_user(n, from, to);
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return uaccess.copy_from_user(n, from, to);
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}
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}
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extern void copy_from_user_overflow(void)
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#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
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__compiletime_warning("copy_from_user() buffer size is not provably correct")
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#endif
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;
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/**
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/**
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* copy_from_user: - Copy a block of data from user space.
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* copy_from_user: - Copy a block of data from user space.
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* @to: Destination address, in kernel space.
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* @to: Destination address, in kernel space.
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@ -284,7 +290,13 @@ __copy_from_user(void *to, const void __user *from, unsigned long n)
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static inline unsigned long __must_check
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static inline unsigned long __must_check
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copy_from_user(void *to, const void __user *from, unsigned long n)
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copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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{
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unsigned int sz = __compiletime_object_size(to);
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might_fault();
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might_fault();
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if (unlikely(sz != -1 && sz < n)) {
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copy_from_user_overflow();
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return n;
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}
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if (access_ok(VERIFY_READ, from, n))
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if (access_ok(VERIFY_READ, from, n))
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n = __copy_from_user(to, from, n);
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n = __copy_from_user(to, from, n);
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else
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else
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@ -2,7 +2,7 @@
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# Makefile for s390-specific library files..
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# Makefile for s390-specific library files..
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#
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#
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lib-y += delay.o string.o uaccess_std.o uaccess_pt.o
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lib-y += delay.o string.o uaccess_std.o uaccess_pt.o usercopy.o
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obj-$(CONFIG_32BIT) += div64.o qrnnd.o ucmpdi2.o
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obj-$(CONFIG_32BIT) += div64.o qrnnd.o ucmpdi2.o
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lib-$(CONFIG_64BIT) += uaccess_mvcos.o
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lib-$(CONFIG_64BIT) += uaccess_mvcos.o
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lib-$(CONFIG_SMP) += spinlock.o
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lib-$(CONFIG_SMP) += spinlock.o
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8
arch/s390/lib/usercopy.c
Normal file
8
arch/s390/lib/usercopy.c
Normal file
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@ -0,0 +1,8 @@
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#include <linux/module.h>
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#include <linux/bug.h>
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void copy_from_user_overflow(void)
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{
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WARN(1, "Buffer overflow detected!\n");
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}
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EXPORT_SYMBOL(copy_from_user_overflow);
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