Re: [PATCH v5 06/10] powerpc/fsl_booke/32: implement KASLR infrastructure
On 2019/8/7 21:04, Michael Ellerman wrote: Jason Yan writes: This patch add support to boot kernel from places other than KERNELBASE. Since CONFIG_RELOCATABLE has already supported, what we need to do is map or copy kernel to a proper place and relocate. Freescale Book-E parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1 entries are not suitable to map the kernel directly in a randomized region, so we chose to copy the kernel to a proper place and restart to relocate. So to be 100% clear you are randomising the location of the kernel in virtual and physical space, by the same amount, and retaining the 1:1 linear mapping. 100% right :) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 77f6ebf97113..755378887912 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -548,6 +548,17 @@ config RELOCATABLE setting can still be useful to bootwrappers that need to know the load address of the kernel (eg. u-boot/mkimage). +config RANDOMIZE_BASE + bool "Randomize the address of the kernel image" + depends on (FSL_BOOKE && FLATMEM && PPC32) + select RELOCATABLE I think this should depend on RELOCATABLE, rather than selecting it. diff --git a/arch/powerpc/kernel/kaslr_booke.c b/arch/powerpc/kernel/kaslr_booke.c new file mode 100644 index ..30f84c0321b2 --- /dev/null +++ b/arch/powerpc/kernel/kaslr_booke.c @@ -0,0 +1,84 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2019 Jason Yan + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. You don't need that paragraph now that you have the SPDX tag. Rather than using a '//' comment followed by a single line block comment you can format it as: // SPDX-License-Identifier: GPL-2.0-only // // Copyright (C) 2019 Jason Yan > +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include Do you really need all those headers? I will remove useless headers. +extern int is_second_reloc; That should be in a header. Any reason why it isn't a bool? Oh yes, it should be in a header. This variable is already defined before and also used in assembly code. I think it was not defined as a bool just because there is no 'bool' in assembly code. cheers .
Re: [PATCH v5 06/10] powerpc/fsl_booke/32: implement KASLR infrastructure
Jason Yan writes: > This patch add support to boot kernel from places other than KERNELBASE. > Since CONFIG_RELOCATABLE has already supported, what we need to do is > map or copy kernel to a proper place and relocate. Freescale Book-E > parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1 > entries are not suitable to map the kernel directly in a randomized > region, so we chose to copy the kernel to a proper place and restart to > relocate. So to be 100% clear you are randomising the location of the kernel in virtual and physical space, by the same amount, and retaining the 1:1 linear mapping. > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index 77f6ebf97113..755378887912 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -548,6 +548,17 @@ config RELOCATABLE > setting can still be useful to bootwrappers that need to know the > load address of the kernel (eg. u-boot/mkimage). > > +config RANDOMIZE_BASE > + bool "Randomize the address of the kernel image" > + depends on (FSL_BOOKE && FLATMEM && PPC32) > + select RELOCATABLE I think this should depend on RELOCATABLE, rather than selecting it. > diff --git a/arch/powerpc/kernel/kaslr_booke.c > b/arch/powerpc/kernel/kaslr_booke.c > new file mode 100644 > index ..30f84c0321b2 > --- /dev/null > +++ b/arch/powerpc/kernel/kaslr_booke.c > @@ -0,0 +1,84 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (C) 2019 Jason Yan > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. You don't need that paragraph now that you have the SPDX tag. Rather than using a '//' comment followed by a single line block comment you can format it as: // SPDX-License-Identifier: GPL-2.0-only // // Copyright (C) 2019 Jason Yan > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include Do you really need all those headers? > +extern int is_second_reloc; That should be in a header. Any reason why it isn't a bool? cheers
[PATCH v5 06/10] powerpc/fsl_booke/32: implement KASLR infrastructure
This patch add support to boot kernel from places other than KERNELBASE. Since CONFIG_RELOCATABLE has already supported, what we need to do is map or copy kernel to a proper place and relocate. Freescale Book-E parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1 entries are not suitable to map the kernel directly in a randomized region, so we chose to copy the kernel to a proper place and restart to relocate. The offset of the kernel was not randomized yet(a fixed 64M is set). We will randomize it in the next patch. Signed-off-by: Jason Yan Cc: Diana Craciun Cc: Michael Ellerman Cc: Christophe Leroy Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Nicholas Piggin Cc: Kees Cook Tested-by: Diana Craciun Reviewed-by: Christophe Leroy --- arch/powerpc/Kconfig | 11 +++ arch/powerpc/kernel/Makefile | 1 + arch/powerpc/kernel/early_32.c| 2 +- arch/powerpc/kernel/fsl_booke_entry_mapping.S | 17 ++-- arch/powerpc/kernel/head_fsl_booke.S | 13 ++- arch/powerpc/kernel/kaslr_booke.c | 84 +++ arch/powerpc/mm/mmu_decl.h| 6 ++ arch/powerpc/mm/nohash/fsl_booke.c| 7 +- 8 files changed, 126 insertions(+), 15 deletions(-) create mode 100644 arch/powerpc/kernel/kaslr_booke.c diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 77f6ebf97113..755378887912 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -548,6 +548,17 @@ config RELOCATABLE setting can still be useful to bootwrappers that need to know the load address of the kernel (eg. u-boot/mkimage). +config RANDOMIZE_BASE + bool "Randomize the address of the kernel image" + depends on (FSL_BOOKE && FLATMEM && PPC32) + select RELOCATABLE + help + Randomizes the virtual address at which the kernel image is + loaded, as a security feature that deters exploit attempts + relying on knowledge of the location of kernel internals. + + If unsure, say N. + config RELOCATABLE_TEST bool "Test relocatable kernel" depends on (PPC64 && RELOCATABLE) diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index ea0c69236789..32f6c5b99307 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -106,6 +106,7 @@ extra-$(CONFIG_PPC_8xx) := head_8xx.o extra-y+= vmlinux.lds obj-$(CONFIG_RELOCATABLE) += reloc_$(BITS).o +obj-$(CONFIG_RANDOMIZE_BASE) += kaslr_booke.o obj-$(CONFIG_PPC32)+= entry_32.o setup_32.o early_32.o obj-$(CONFIG_PPC64)+= dma-iommu.o iommu.o diff --git a/arch/powerpc/kernel/early_32.c b/arch/powerpc/kernel/early_32.c index 3482118ffe76..fe8347cdc07d 100644 --- a/arch/powerpc/kernel/early_32.c +++ b/arch/powerpc/kernel/early_32.c @@ -32,5 +32,5 @@ notrace unsigned long __init early_init(unsigned long dt_ptr) apply_feature_fixups(); - return KERNELBASE + offset; + return kimage_vaddr + offset; } diff --git a/arch/powerpc/kernel/fsl_booke_entry_mapping.S b/arch/powerpc/kernel/fsl_booke_entry_mapping.S index de0980945510..de7ee682bb4a 100644 --- a/arch/powerpc/kernel/fsl_booke_entry_mapping.S +++ b/arch/powerpc/kernel/fsl_booke_entry_mapping.S @@ -155,23 +155,22 @@ skpinv: addir6,r6,1 /* Increment */ #if defined(ENTRY_MAPPING_BOOT_SETUP) -/* 6. Setup KERNELBASE mapping in TLB1[0] */ +/* 6. Setup kimage_vaddr mapping in TLB1[0] */ lis r6,0x1000 /* Set MAS0(TLBSEL) = TLB1(1), ESEL = 0 */ mtspr SPRN_MAS0,r6 lis r6,(MAS1_VALID|MAS1_IPROT)@h ori r6,r6,(MAS1_TSIZE(BOOK3E_PAGESZ_64M))@l mtspr SPRN_MAS1,r6 - lis r6,MAS2_VAL(PAGE_OFFSET, BOOK3E_PAGESZ_64M, M_IF_NEEDED)@h - ori r6,r6,MAS2_VAL(PAGE_OFFSET, BOOK3E_PAGESZ_64M, M_IF_NEEDED)@l - mtspr SPRN_MAS2,r6 + lis r6,MAS2_EPN_MASK(BOOK3E_PAGESZ_64M)@h + ori r6,r6,MAS2_EPN_MASK(BOOK3E_PAGESZ_64M)@l + and r6,r6,r20 + ori r6,r6,M_IF_NEEDED@l + mtspr SPRN_MAS2,r6 mtspr SPRN_MAS3,r8 tlbwe -/* 7. Jump to KERNELBASE mapping */ - lis r6,(KERNELBASE & ~0xfff)@h - ori r6,r6,(KERNELBASE & ~0xfff)@l - rlwinm r7,r25,0,0x03ff - add r6,r7,r6 +/* 7. Jump to kimage_vaddr mapping */ + mr r6,r20 #elif defined(ENTRY_MAPPING_KEXEC_SETUP) /* diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S index 2083382dd662..aa55832e7506 100644 --- a/arch/powerpc/kernel/head_fsl_booke.S +++ b/arch/powerpc/kernel/head_fsl_booke.S @@ -155,6 +155,8 @@ _ENTRY(_start); */ _ENTRY(__early_start) + LOAD_REG_ADDR_PIC(r20, kimage_vaddr) + lwz r20,0(r20) #define ENTRY_MAPPING_BOOT_SETUP #include "fsl_booke_entry_mapping.S" @@ -277,8 +279,8
