| Message ID | 20190809100800.5426-7-yanaijie@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | implement KASLR for powerpc/fsl_booke/32 | expand |
On Fri, Aug 09, 2019 at 06:07:54PM +0800, Jason Yan wrote: > 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@huawei.com> > Cc: Diana Craciun <diana.craciun@nxp.com> > Cc: Michael Ellerman <mpe@ellerman.id.au> > Cc: Christophe Leroy <christophe.leroy@c-s.fr> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Cc: Paul Mackerras <paulus@samba.org> > Cc: Nicholas Piggin <npiggin@gmail.com> > Cc: Kees Cook <keescook@chromium.org> > Tested-by: Diana Craciun <diana.craciun@nxp.com> > Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> > --- > 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 | 62 +++++++++++++++++++ > arch/powerpc/mm/mmu_decl.h | 7 +++ > arch/powerpc/mm/nohash/fsl_booke.c | 7 ++- > 8 files changed, 105 insertions(+), 15 deletions(-) > create mode 100644 arch/powerpc/kernel/kaslr_booke.c > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index 77f6ebf97113..710c12ef7159 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) > + depends on 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. > + Why is N the safe default (other than concerns about code maturity, though arm64 and mips don't seem to have updated this recommendation after several years)? On x86 this defaults to Y. > diff --git a/arch/powerpc/kernel/fsl_booke_entry_mapping.S b/arch/powerpc/kernel/fsl_booke_entry_mapping.S > index f4d3eaae54a9..641920d4f694 100644 > --- a/arch/powerpc/kernel/fsl_booke_entry_mapping.S > +++ b/arch/powerpc/kernel/fsl_booke_entry_mapping.S > @@ -155,23 +155,22 @@ skpinv: addi r6,r6,1 /* Increment */ > > #if defined(ENTRY_MAPPING_BOOT_SETUP) > > -/* 6. Setup KERNELBASE mapping in TLB1[0] */ > +/* 6. Setup kernstart_virt_addr 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, MAS2_M_IF_NEEDED)@h > - ori r6,r6,MAS2_VAL(PAGE_OFFSET, BOOK3E_PAGESZ_64M, MAS2_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,MAS2_M_IF_NEEDED@l > + mtspr SPRN_MAS2,r6 Please use tabs rather than spaces between the mnemonic and the arguments. It looks like that was the last user of MAS2_VAL so let's remove it. > diff --git a/arch/powerpc/kernel/kaslr_booke.c b/arch/powerpc/kernel/kaslr_booke.c > new file mode 100644 > index 000000000000..f8dc60534ac1 > --- /dev/null > +++ b/arch/powerpc/kernel/kaslr_booke.c Shouldn't this go under arch/powerpc/mm/nohash? > +/* > + * 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; Why KERNELBASE and not kernstart_addr? > + > + offset = kaslr_choose_location(dt_ptr, size, kernel_sz); > + > + if (offset == 0) > + return; > + > + kernstart_virt_addr += offset; > + kernstart_addr += offset; > + > + is_second_reloc = 1; > + > + if (offset >= SZ_64M) { > + tlb_virt = round_down(kernstart_virt_addr, SZ_64M); > + tlb_phys = round_down(kernstart_addr, SZ_64M); If kernstart_addr wasn't 64M-aligned before adding offset, then "offset >= SZ_64M" is not necessarily going to detect when you've crossed a mapping boundary. > + > + /* 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 *)kernstart_virt_addr, (void *)KERNELBASE, kernel_sz); > + > + reloc_kernel_entry(dt_ptr, kernstart_virt_addr); > +} After copying, call flush_icache_range() on the destination. > diff --git a/arch/powerpc/mm/nohash/fsl_booke.c b/arch/powerpc/mm/nohash/fsl_booke.c > index 556e3cd52a35..2dc27cf88add 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 = kernstart_virt_addr; > + 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); Are you assuming that available memory starts at physical address zero? This isn't true of some partitioning scenarios, or in a kdump crash kernel. -Scott
Le 28/08/2019 à 06:54, Scott Wood a écrit : > On Fri, Aug 09, 2019 at 06:07:54PM +0800, Jason Yan wrote: >> 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@huawei.com> >> Cc: Diana Craciun <diana.craciun@nxp.com> >> Cc: Michael Ellerman <mpe@ellerman.id.au> >> Cc: Christophe Leroy <christophe.leroy@c-s.fr> >> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> >> Cc: Paul Mackerras <paulus@samba.org> >> Cc: Nicholas Piggin <npiggin@gmail.com> >> Cc: Kees Cook <keescook@chromium.org> >> Tested-by: Diana Craciun <diana.craciun@nxp.com> >> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> >> --- >> 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 | 62 +++++++++++++++++++ >> arch/powerpc/mm/mmu_decl.h | 7 +++ >> arch/powerpc/mm/nohash/fsl_booke.c | 7 ++- >> 8 files changed, 105 insertions(+), 15 deletions(-) >> create mode 100644 arch/powerpc/kernel/kaslr_booke.c >> [...] >> diff --git a/arch/powerpc/kernel/kaslr_booke.c b/arch/powerpc/kernel/kaslr_booke.c >> new file mode 100644 >> index 000000000000..f8dc60534ac1 >> --- /dev/null >> +++ b/arch/powerpc/kernel/kaslr_booke.c > > Shouldn't this go under arch/powerpc/mm/nohash? > >> +/* >> + * 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; > > Why KERNELBASE and not kernstart_addr? > >> + >> + offset = kaslr_choose_location(dt_ptr, size, kernel_sz); >> + >> + if (offset == 0) >> + return; >> + >> + kernstart_virt_addr += offset; >> + kernstart_addr += offset; >> + >> + is_second_reloc = 1; >> + >> + if (offset >= SZ_64M) { >> + tlb_virt = round_down(kernstart_virt_addr, SZ_64M); >> + tlb_phys = round_down(kernstart_addr, SZ_64M); > > If kernstart_addr wasn't 64M-aligned before adding offset, then "offset >> = SZ_64M" is not necessarily going to detect when you've crossed a > mapping boundary. > >> + >> + /* 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 *)kernstart_virt_addr, (void *)KERNELBASE, kernel_sz); >> + >> + reloc_kernel_entry(dt_ptr, kernstart_virt_addr); >> +} > > After copying, call flush_icache_range() on the destination. Function copy_and_flush() does the copy and the flush. I think it should be used instead of memcpy() + flush_icache_range() Christophe
On 2019/8/28 12:54, Scott Wood wrote: > On Fri, Aug 09, 2019 at 06:07:54PM +0800, Jason Yan wrote: >> 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@huawei.com> >> Cc: Diana Craciun <diana.craciun@nxp.com> >> Cc: Michael Ellerman <mpe@ellerman.id.au> >> Cc: Christophe Leroy <christophe.leroy@c-s.fr> >> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> >> Cc: Paul Mackerras <paulus@samba.org> >> Cc: Nicholas Piggin <npiggin@gmail.com> >> Cc: Kees Cook <keescook@chromium.org> >> Tested-by: Diana Craciun <diana.craciun@nxp.com> >> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> >> --- >> 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 | 62 +++++++++++++++++++ >> arch/powerpc/mm/mmu_decl.h | 7 +++ >> arch/powerpc/mm/nohash/fsl_booke.c | 7 ++- >> 8 files changed, 105 insertions(+), 15 deletions(-) >> create mode 100644 arch/powerpc/kernel/kaslr_booke.c >> >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig >> index 77f6ebf97113..710c12ef7159 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) >> + depends on 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. >> + > > Why is N the safe default (other than concerns about code maturity, > though arm64 and mips don't seem to have updated this recommendation > after several years)? On x86 this defaults to Y. > Actually I would like to set this default Y. I was just wondering if people like this feature or not at the beginning so I had to be more careful. >> diff --git a/arch/powerpc/kernel/fsl_booke_entry_mapping.S b/arch/powerpc/kernel/fsl_booke_entry_mapping.S >> index f4d3eaae54a9..641920d4f694 100644 >> --- a/arch/powerpc/kernel/fsl_booke_entry_mapping.S >> +++ b/arch/powerpc/kernel/fsl_booke_entry_mapping.S >> @@ -155,23 +155,22 @@ skpinv: addi r6,r6,1 /* Increment */ >> >> #if defined(ENTRY_MAPPING_BOOT_SETUP) >> >> -/* 6. Setup KERNELBASE mapping in TLB1[0] */ >> +/* 6. Setup kernstart_virt_addr 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, MAS2_M_IF_NEEDED)@h >> - ori r6,r6,MAS2_VAL(PAGE_OFFSET, BOOK3E_PAGESZ_64M, MAS2_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,MAS2_M_IF_NEEDED@l >> + mtspr SPRN_MAS2,r6 > > Please use tabs rather than spaces between the mnemonic and the > arguments. > > It looks like that was the last user of MAS2_VAL so let's remove it. > OK. >> diff --git a/arch/powerpc/kernel/kaslr_booke.c b/arch/powerpc/kernel/kaslr_booke.c >> new file mode 100644 >> index 000000000000..f8dc60534ac1 >> --- /dev/null >> +++ b/arch/powerpc/kernel/kaslr_booke.c > > Shouldn't this go under arch/powerpc/mm/nohash? > >> +/* >> + * 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; > > Why KERNELBASE and not kernstart_addr? > Did you mean kernstart_virt_addr? It should be kernstart_virt_addr. >> + >> + offset = kaslr_choose_location(dt_ptr, size, kernel_sz); >> + >> + if (offset == 0) >> + return; >> + >> + kernstart_virt_addr += offset; >> + kernstart_addr += offset; >> + >> + is_second_reloc = 1; >> + >> + if (offset >= SZ_64M) { >> + tlb_virt = round_down(kernstart_virt_addr, SZ_64M); >> + tlb_phys = round_down(kernstart_addr, SZ_64M); > > If kernstart_addr wasn't 64M-aligned before adding offset, then "offset >> = SZ_64M" is not necessarily going to detect when you've crossed a > mapping boundary. > >> + >> + /* 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 *)kernstart_virt_addr, (void *)KERNELBASE, kernel_sz); >> + >> + reloc_kernel_entry(dt_ptr, kernstart_virt_addr); >> +} > > After copying, call flush_icache_range() on the destination. > OK >> diff --git a/arch/powerpc/mm/nohash/fsl_booke.c b/arch/powerpc/mm/nohash/fsl_booke.c >> index 556e3cd52a35..2dc27cf88add 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 = kernstart_virt_addr; >> + 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); > > Are you assuming that available memory starts at physical address zero? > This isn't true of some partitioning scenarios, or in a kdump crash > kernel. > I'm not assuming that but I haven't tested that case for now. I will reconsider and test these scenarios and fix all bugs. > -Scott > > . >
On Wed, 2019-08-28 at 19:03 +0800, Jason Yan wrote: > > On 2019/8/28 12:54, Scott Wood wrote: > > On Fri, Aug 09, 2019 at 06:07:54PM +0800, Jason Yan wrote: > > > +/* > > > + * 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; > > > > Why KERNELBASE and not kernstart_addr? > > > > Did you mean kernstart_virt_addr? It should be kernstart_virt_addr. Yes, kernstart_virt_addr. KERNELBASE will be incorrect if the kernel was loaded at a nonzero physical address without CONFIG_PHYSICAL_START being adjusted to match. -Scott
On 2019/8/28 13:47, Christophe Leroy wrote: > > > Le 28/08/2019 à 06:54, Scott Wood a écrit : >> On Fri, Aug 09, 2019 at 06:07:54PM +0800, Jason Yan wrote: >>> 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@huawei.com> >>> Cc: Diana Craciun <diana.craciun@nxp.com> >>> Cc: Michael Ellerman <mpe@ellerman.id.au> >>> Cc: Christophe Leroy <christophe.leroy@c-s.fr> >>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> >>> Cc: Paul Mackerras <paulus@samba.org> >>> Cc: Nicholas Piggin <npiggin@gmail.com> >>> Cc: Kees Cook <keescook@chromium.org> >>> Tested-by: Diana Craciun <diana.craciun@nxp.com> >>> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> >>> --- >>> 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 | 62 +++++++++++++++++++ >>> arch/powerpc/mm/mmu_decl.h | 7 +++ >>> arch/powerpc/mm/nohash/fsl_booke.c | 7 ++- >>> 8 files changed, 105 insertions(+), 15 deletions(-) >>> create mode 100644 arch/powerpc/kernel/kaslr_booke.c >>> > > [...] > >>> diff --git a/arch/powerpc/kernel/kaslr_booke.c >>> b/arch/powerpc/kernel/kaslr_booke.c >>> new file mode 100644 >>> index 000000000000..f8dc60534ac1 >>> --- /dev/null >>> +++ b/arch/powerpc/kernel/kaslr_booke.c >> >> Shouldn't this go under arch/powerpc/mm/nohash? >> >>> +/* >>> + * 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; >> >> Why KERNELBASE and not kernstart_addr? >> >>> + >>> + offset = kaslr_choose_location(dt_ptr, size, kernel_sz); >>> + >>> + if (offset == 0) >>> + return; >>> + >>> + kernstart_virt_addr += offset; >>> + kernstart_addr += offset; >>> + >>> + is_second_reloc = 1; >>> + >>> + if (offset >= SZ_64M) { >>> + tlb_virt = round_down(kernstart_virt_addr, SZ_64M); >>> + tlb_phys = round_down(kernstart_addr, SZ_64M); >> >> If kernstart_addr wasn't 64M-aligned before adding offset, then "offset >>> = SZ_64M" is not necessarily going to detect when you've crossed a >> mapping boundary. >> >>> + >>> + /* 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 *)kernstart_virt_addr, (void *)KERNELBASE, kernel_sz); >>> + >>> + reloc_kernel_entry(dt_ptr, kernstart_virt_addr); >>> +} >> >> After copying, call flush_icache_range() on the destination. > > Function copy_and_flush() does the copy and the flush. I think it should > be used instead of memcpy() + flush_icache_range() > Hi Christophe, Thanks for the suggestion. But I think copy_and_flush() is not included in fsl booke code, maybe move this function to misc.S? > Christophe > > . >
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 77f6ebf97113..710c12ef7159 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) + depends on 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..0c5849fd936d 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 kernstart_virt_addr + offset; } diff --git a/arch/powerpc/kernel/fsl_booke_entry_mapping.S b/arch/powerpc/kernel/fsl_booke_entry_mapping.S index f4d3eaae54a9..641920d4f694 100644 --- a/arch/powerpc/kernel/fsl_booke_entry_mapping.S +++ b/arch/powerpc/kernel/fsl_booke_entry_mapping.S @@ -155,23 +155,22 @@ skpinv: addi r6,r6,1 /* Increment */ #if defined(ENTRY_MAPPING_BOOT_SETUP) -/* 6. Setup KERNELBASE mapping in TLB1[0] */ +/* 6. Setup kernstart_virt_addr 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, MAS2_M_IF_NEEDED)@h - ori r6,r6,MAS2_VAL(PAGE_OFFSET, BOOK3E_PAGESZ_64M, MAS2_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,MAS2_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,r25,0,0x03ffffff - add r6,r7,r6 +/* 7. Jump to kernstart_virt_addr 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..f7a5c5f03c72 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, kernstart_virt_addr) + 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, kernstart_virt_addr@ha + lwz r4, kernstart_virt_addr@l(r3) stw r5, 0(r4) /* Save abatron_pteptrs at a fixed location */ stw r6, 0(r5) @@ -1067,7 +1069,12 @@ __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 */ + lis r7,KERNELBASE@h + ori r7,r7,KERNELBASE@l + cmpw r20,r7 /* if kimage_vaddr != KERNELBASE, randomized */ + beq 2f + li r4,0 +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..f8dc60534ac1 --- /dev/null +++ b/arch/powerpc/kernel/kaslr_booke.c @@ -0,0 +1,62 @@ +// SPDX-License-Identifier: GPL-2.0-only +// +// Copyright (C) 2019 Jason Yan <yanaijie@huawei.com> + +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/string.h> +#include <linux/types.h> +#include <linux/mm.h> +#include <linux/swap.h> +#include <linux/stddef.h> +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/memblock.h> +#include <asm/pgalloc.h> +#include <asm/prom.h> +#include <mm/mmu_decl.h> + +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 SZ_64M; +} + +/* + * 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; + + kernstart_virt_addr += offset; + kernstart_addr += offset; + + is_second_reloc = 1; + + if (offset >= SZ_64M) { + tlb_virt = round_down(kernstart_virt_addr, 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 *)kernstart_virt_addr, (void *)KERNELBASE, kernel_sz); + + reloc_kernel_entry(dt_ptr, kernstart_virt_addr); +} diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h index 804da298beb3..213997d69729 100644 --- a/arch/powerpc/mm/mmu_decl.h +++ b/arch/powerpc/mm/mmu_decl.h @@ -144,10 +144,17 @@ extern int switch_to_as1(void); extern void restore_to_as0(int esel, int offset, void *dt_ptr, int bootcpu); void create_tlb_entry(phys_addr_t phys, unsigned long virt, int entry); void reloc_kernel_entry(void *fdt, int addr); +extern int is_second_reloc; #endif 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..2dc27cf88add 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 = kernstart_virt_addr; + 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