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51faada71a
Introduce new build option ENABLE_STACK_PROTECTOR. It enables compilation of all BL images with one of the GCC -fstack-protector-* options. A new platform function plat_get_stack_protector_canary() is introduced. It returns a value that is used to initialize the canary for stack corruption detection. Returning a random value will prevent an attacker from predicting the value and greatly increase the effectiveness of the protection. A message is printed at the ERROR level when a stack corruption is detected. To be effective, the global data must be stored at an address lower than the base of the stacks. Failure to do so would allow an attacker to overwrite the canary as part of an attack which would void the protection. FVP implementation of plat_get_stack_protector_canary is weak as there is no real source of entropy on the FVP. It therefore relies on a timer's value, which could be predictable. Change-Id: Icaaee96392733b721fa7c86a81d03660d3c1bc06 Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
140 lines
4.5 KiB
ArmAsm
140 lines
4.5 KiB
ArmAsm
/*
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* Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of ARM nor the names of its contributors may be used
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* to endorse or promote products derived from this software without specific
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* prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <arch.h>
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#include <asm_macros.S>
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#include <bl_common.h>
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.globl bl2u_entrypoint
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func bl2u_entrypoint
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/*---------------------------------------------
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* Store the extents of the tzram available to
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* BL2U and other platform specific information
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* for future use. x0 is currently not used.
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* ---------------------------------------------
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*/
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mov x20, x1
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mov x21, x2
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/* ---------------------------------------------
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* Set the exception vector to something sane.
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* ---------------------------------------------
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*/
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adr x0, early_exceptions
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msr vbar_el1, x0
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isb
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/* ---------------------------------------------
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* Enable the SError interrupt now that the
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* exception vectors have been setup.
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* ---------------------------------------------
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*/
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msr daifclr, #DAIF_ABT_BIT
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/* ---------------------------------------------
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* Enable the instruction cache, stack pointer
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* and data access alignment checks
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* ---------------------------------------------
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*/
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mov x1, #(SCTLR_I_BIT | SCTLR_A_BIT | SCTLR_SA_BIT)
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mrs x0, sctlr_el1
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orr x0, x0, x1
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msr sctlr_el1, x0
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isb
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/* ---------------------------------------------
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* Invalidate the RW memory used by the BL2U
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* image. This includes the data and NOBITS
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* sections. This is done to safeguard against
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* possible corruption of this memory by dirty
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* cache lines in a system cache as a result of
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* use by an earlier boot loader stage.
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* ---------------------------------------------
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*/
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adr x0, __RW_START__
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adr x1, __RW_END__
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sub x1, x1, x0
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bl inv_dcache_range
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/* ---------------------------------------------
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* Zero out NOBITS sections. There are 2 of them:
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* - the .bss section;
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* - the coherent memory section.
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* ---------------------------------------------
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*/
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ldr x0, =__BSS_START__
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ldr x1, =__BSS_SIZE__
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bl zeromem
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/* --------------------------------------------
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* Allocate a stack whose memory will be marked
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* as Normal-IS-WBWA when the MMU is enabled.
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* There is no risk of reading stale stack
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* memory after enabling the MMU as only the
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* primary cpu is running at the moment.
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* --------------------------------------------
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*/
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bl plat_set_my_stack
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/* ---------------------------------------------
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* Initialize the stack protector canary before
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* any C code is called.
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* ---------------------------------------------
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*/
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#if STACK_PROTECTOR_ENABLED
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bl update_stack_protector_canary
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#endif
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/* ---------------------------------------------
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* Perform early platform setup & platform
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* specific early arch. setup e.g. mmu setup
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* ---------------------------------------------
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*/
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mov x0, x20
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mov x1, x21
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bl bl2u_early_platform_setup
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bl bl2u_plat_arch_setup
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/* ---------------------------------------------
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* Jump to bl2u_main function.
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* ---------------------------------------------
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*/
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bl bl2u_main
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/* ---------------------------------------------
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* Should never reach this point.
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* ---------------------------------------------
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*/
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no_ret plat_panic_handler
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endfunc bl2u_entrypoint
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