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Message-ID: <602e552f-c2ec-38e0-f5be-da1653b6e0c3@huawei.com> Date: Wed, 31 Jul 2019 10:03:01 +0800 From: Jason Yan <yanaijie@...wei.com> To: Christophe Leroy <christophe.leroy@....fr>, <mpe@...erman.id.au>, <linuxppc-dev@...ts.ozlabs.org>, <diana.craciun@....com>, <benh@...nel.crashing.org>, <paulus@...ba.org>, <npiggin@...il.com>, <keescook@...omium.org>, <kernel-hardening@...ts.openwall.com> CC: <linux-kernel@...r.kernel.org>, <wangkefeng.wang@...wei.com>, <yebin10@...wei.com>, <thunder.leizhen@...wei.com>, <jingxiangfeng@...wei.com>, <fanchengyang@...wei.com>, <zhaohongjiang@...wei.com> Subject: Re: [PATCH v2 06/10] powerpc/fsl_booke/32: implement KASLR infrastructure On 2019/7/30 17:34, Christophe Leroy wrote: > > > Le 30/07/2019 à 09:42, Jason Yan a écrit : >> 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 <yanaijie@...wei.com> >> Cc: Diana Craciun <diana.craciun@....com> >> Cc: Michael Ellerman <mpe@...erman.id.au> >> Cc: Christophe Leroy <christophe.leroy@....fr> >> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org> >> Cc: Paul Mackerras <paulus@...ba.org> >> Cc: Nicholas Piggin <npiggin@...il.com> >> Cc: Kees Cook <keescook@...omium.org> >> --- >> arch/powerpc/Kconfig | 11 +++ >> arch/powerpc/kernel/Makefile | 1 + >> arch/powerpc/kernel/early_32.c | 2 +- >> arch/powerpc/kernel/fsl_booke_entry_mapping.S | 13 ++- >> arch/powerpc/kernel/head_fsl_booke.S | 15 +++- >> 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(+), 13 deletions(-) >> create mode 100644 arch/powerpc/kernel/kaslr_booke.c >> > > [...] > >> diff --git a/arch/powerpc/kernel/head_fsl_booke.S >> b/arch/powerpc/kernel/head_fsl_booke.S >> index 2083382dd662..a466c0f0d028 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 @@ set_ivor: >> ori r6, r6, swapper_pg_dir@l >> lis r5, abatron_pteptrs@h >> ori r5, r5, abatron_pteptrs@l >> - lis r4, KERNELBASE@h >> - ori r4, r4, KERNELBASE@l >> + lis r3, kimage_vaddr@ha >> + lwz r4, kimage_vaddr@l(r3) >> stw r5, 0(r4) /* Save abatron_pteptrs at a fixed location */ >> stw r6, 0(r5) >> @@ -1067,7 +1069,14 @@ __secondary_start: >> mr r5,r25 /* phys kernel start */ >> rlwinm r5,r5,0,~0x3ffffff /* aligned 64M */ >> subf r4,r5,r4 /* memstart_addr - phys kernel start */ >> - li r5,0 /* no device tree */ >> +#ifdef CONFIG_RANDOMIZE_BASE > > Is that #ifdef really necessary ? Wouldn't it also work as expected when > CONFIG_RANDOMIZE_BASE is not selected ? > Yes, it will also work if CONFIG_RANDOMIZE_BASE is not enabled. I can remove it. >> + lis r7,KERNELBASE@h >> + ori r7,r7,KERNELBASE@l >> + cmpw r20,r7 /* if kimage_vaddr != KERNELBASE, >> randomized */ >> + beq 2f >> + li r4,0 >> +#endif >> +2: li r5,0 /* no device tree */ >> li r6,0 /* not boot cpu */ >> bl restore_to_as0 >> diff --git a/arch/powerpc/kernel/kaslr_booke.c >> b/arch/powerpc/kernel/kaslr_booke.c >> new file mode 100644 >> index 000000000000..960bce4aa8b9 >> --- /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 <yanaijie@...wei.com> >> + * >> + * 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. >> + */ >> + >> +#include <linux/signal.h> >> +#include <linux/sched.h> >> +#include <linux/kernel.h> >> +#include <linux/errno.h> >> +#include <linux/string.h> >> +#include <linux/types.h> >> +#include <linux/ptrace.h> >> +#include <linux/mman.h> >> +#include <linux/mm.h> >> +#include <linux/swap.h> >> +#include <linux/stddef.h> >> +#include <linux/vmalloc.h> >> +#include <linux/init.h> >> +#include <linux/delay.h> >> +#include <linux/highmem.h> >> +#include <linux/memblock.h> >> +#include <asm/pgalloc.h> >> +#include <asm/prom.h> >> +#include <asm/io.h> >> +#include <asm/mmu_context.h> >> +#include <asm/pgtable.h> >> +#include <asm/mmu.h> >> +#include <linux/uaccess.h> >> +#include <asm/smp.h> >> +#include <asm/machdep.h> >> +#include <asm/setup.h> >> +#include <asm/paca.h> >> +#include <mm/mmu_decl.h> >> + >> +extern int is_second_reloc; > > Couldn't the above be a bool ? > This variable is both used in C and assembly. Use int make it more explicit to compare it with 0 or 1 in assembly. >> + >> +static unsigned long __init kaslr_choose_location(void *dt_ptr, >> phys_addr_t size, >> + unsigned long kernel_sz) >> +{ >> + /* return a fixed offset of 64M for now */ >> + return 0x4000000; > > 64 << 20 would maybe be more explicit than 0x4000000. > > Or return SZ_64M ? > SZ_64M would be good. > Christophe > >> +} >> + >> +/* >> + * To see if we need to relocate the kernel to a random offset >> + * void *dt_ptr - address of the device tree >> + * phys_addr_t size - size of the first memory block >> + */ >> +notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size) >> +{ >> + unsigned long tlb_virt; >> + phys_addr_t tlb_phys; >> + unsigned long offset; >> + unsigned long kernel_sz; >> + >> + kernel_sz = (unsigned long)_end - KERNELBASE; >> + >> + offset = kaslr_choose_location(dt_ptr, size, kernel_sz); >> + >> + if (offset == 0) >> + return; >> + >> + kimage_vaddr += offset; >> + kernstart_addr += offset; >> + >> + is_second_reloc = 1; >> + >> + if (offset >= SZ_64M) { >> + tlb_virt = round_down(kimage_vaddr, SZ_64M); >> + tlb_phys = round_down(kernstart_addr, SZ_64M); >> + >> + /* Create kernel map to relocate in */ >> + create_tlb_entry(tlb_phys, tlb_virt, 1); >> + } >> + >> + /* Copy the kernel to it's new location and run */ >> + memcpy((void *)kimage_vaddr, (void *)KERNELBASE, kernel_sz); >> + >> + reloc_kernel_entry(dt_ptr, kimage_vaddr); >> +} >> diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h >> index 804da298beb3..9332772c8a66 100644 >> --- a/arch/powerpc/mm/mmu_decl.h >> +++ b/arch/powerpc/mm/mmu_decl.h >> @@ -148,6 +148,12 @@ void reloc_kernel_entry(void *fdt, int addr); >> extern void loadcam_entry(unsigned int index); >> extern void loadcam_multi(int first_idx, int num, int tmp_idx); >> +#ifdef CONFIG_RANDOMIZE_BASE >> +void kaslr_early_init(void *dt_ptr, phys_addr_t size); >> +#else >> +static inline void kaslr_early_init(void *dt_ptr, phys_addr_t size) {} >> +#endif >> + >> struct tlbcam { >> u32 MAS0; >> u32 MAS1; >> diff --git a/arch/powerpc/mm/nohash/fsl_booke.c >> b/arch/powerpc/mm/nohash/fsl_booke.c >> index 556e3cd52a35..8d25a8dc965f 100644 >> --- a/arch/powerpc/mm/nohash/fsl_booke.c >> +++ b/arch/powerpc/mm/nohash/fsl_booke.c >> @@ -263,7 +263,8 @@ void setup_initial_memory_limit(phys_addr_t >> first_memblock_base, >> int __initdata is_second_reloc; >> notrace void __init relocate_init(u64 dt_ptr, phys_addr_t start) >> { >> - unsigned long base = KERNELBASE; >> + unsigned long base = kimage_vaddr; >> + phys_addr_t size; >> kernstart_addr = start; >> if (is_second_reloc) { >> @@ -291,7 +292,7 @@ notrace void __init relocate_init(u64 dt_ptr, >> phys_addr_t start) >> start &= ~0x3ffffff; >> base &= ~0x3ffffff; >> virt_phys_offset = base - start; >> - early_get_first_memblock_info(__va(dt_ptr), NULL); >> + early_get_first_memblock_info(__va(dt_ptr), &size); >> /* >> * We now get the memstart_addr, then we should check if this >> * address is the same as what the PAGE_OFFSET map to now. If >> @@ -316,6 +317,8 @@ notrace void __init relocate_init(u64 dt_ptr, >> phys_addr_t start) >> /* We should never reach here */ >> panic("Relocation error"); >> } >> + >> + kaslr_early_init(__va(dt_ptr), size); >> } >> #endif >> #endif >> > > . >
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