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75045f77f7
Currently, most fixups for attempting to access userspace memory are handled using _ASM_EXTABLE, which is also used for various other types of fixups (e.g. safe MSR access, IRET failures, and a bunch of other things). In order to make it possible to add special safety checks to uaccess fixups (in particular, checking whether the fault address is actually in userspace), introduce a new exception table handler ex_handler_uaccess() and wire it up to all the user access fixups (excluding ones that already use _ASM_EXTABLE_EX). Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Kees Cook <keescook@chromium.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: kernel-hardening@lists.openwall.com Cc: dvyukov@google.com Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Cc: Borislav Petkov <bp@alien8.de> Link: https://lkml.kernel.org/r/20180828201421.157735-5-jannh@google.com
103 lines
2 KiB
ArmAsm
103 lines
2 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* __put_user functions.
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*
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* (C) Copyright 2005 Linus Torvalds
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* (C) Copyright 2005 Andi Kleen
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* (C) Copyright 2008 Glauber Costa
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*
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* These functions have a non-standard call interface
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* to make them more efficient, especially as they
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* return an error value in addition to the "real"
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* return value.
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*/
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#include <linux/linkage.h>
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#include <asm/thread_info.h>
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#include <asm/errno.h>
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#include <asm/asm.h>
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#include <asm/smap.h>
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#include <asm/export.h>
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/*
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* __put_user_X
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*
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* Inputs: %eax[:%edx] contains the data
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* %ecx contains the address
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*
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* Outputs: %eax is error code (0 or -EFAULT)
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*
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* These functions should not modify any other registers,
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* as they get called from within inline assembly.
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*/
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#define ENTER mov PER_CPU_VAR(current_task), %_ASM_BX
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#define EXIT ASM_CLAC ; \
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ret
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.text
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ENTRY(__put_user_1)
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ENTER
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cmp TASK_addr_limit(%_ASM_BX),%_ASM_CX
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jae bad_put_user
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ASM_STAC
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1: movb %al,(%_ASM_CX)
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xor %eax,%eax
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EXIT
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ENDPROC(__put_user_1)
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EXPORT_SYMBOL(__put_user_1)
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ENTRY(__put_user_2)
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ENTER
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mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
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sub $1,%_ASM_BX
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cmp %_ASM_BX,%_ASM_CX
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jae bad_put_user
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ASM_STAC
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2: movw %ax,(%_ASM_CX)
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xor %eax,%eax
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EXIT
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ENDPROC(__put_user_2)
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EXPORT_SYMBOL(__put_user_2)
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ENTRY(__put_user_4)
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ENTER
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mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
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sub $3,%_ASM_BX
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cmp %_ASM_BX,%_ASM_CX
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jae bad_put_user
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ASM_STAC
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3: movl %eax,(%_ASM_CX)
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xor %eax,%eax
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EXIT
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ENDPROC(__put_user_4)
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EXPORT_SYMBOL(__put_user_4)
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ENTRY(__put_user_8)
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ENTER
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mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
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sub $7,%_ASM_BX
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cmp %_ASM_BX,%_ASM_CX
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jae bad_put_user
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ASM_STAC
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4: mov %_ASM_AX,(%_ASM_CX)
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#ifdef CONFIG_X86_32
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5: movl %edx,4(%_ASM_CX)
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#endif
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xor %eax,%eax
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EXIT
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ENDPROC(__put_user_8)
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EXPORT_SYMBOL(__put_user_8)
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bad_put_user:
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movl $-EFAULT,%eax
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EXIT
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END(bad_put_user)
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_ASM_EXTABLE_UA(1b, bad_put_user)
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_ASM_EXTABLE_UA(2b, bad_put_user)
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_ASM_EXTABLE_UA(3b, bad_put_user)
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_ASM_EXTABLE_UA(4b, bad_put_user)
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#ifdef CONFIG_X86_32
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_ASM_EXTABLE_UA(5b, bad_put_user)
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#endif
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