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| Started by | Miles Chen <miles.chen@mediatek.com> |
|---|---|
| First post | 2017-02-28 08:20 +0100 |
| Last post | 2017-02-28 14:00 +0100 |
| Articles | 4 — 4 participants |
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[PATCH] arm64: dump: hide kernel pointers Miles Chen <miles.chen@mediatek.com> - 2017-02-28 08:20 +0100
Re: [PATCH] arm64: dump: hide kernel pointers Mark Rutland <mark.rutland@arm.com> - 2017-02-28 11:30 +0100
Re: [PATCH] arm64: dump: hide kernel pointers Will Deacon <will.deacon@arm.com> - 2017-03-01 05:00 +0100
Re: [PATCH] arm64: dump: hide kernel pointers Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-02-28 14:00 +0100
| From | Miles Chen <miles.chen@mediatek.com> |
|---|---|
| Date | 2017-02-28 08:20 +0100 |
| Subject | [PATCH] arm64: dump: hide kernel pointers |
| Message-ID | <tfKeJ-174-7@gated-at.bofh.it> |
Mask kernel pointers of /sys/kernel/debug/kernel_page_tables entry like
/proc/vmallocinfo does.
With sysctl kernel.kptr_restrict=0 or 1:
cat /sys/kernel/debug/kernel_page_tables
---[ Modules start ]---
---[ Modules end ]---
---[ vmalloc() Area ]---
ffffff8008000000-ffffff8008010000 64K PTE RW NX SHD AF...
ffffff8008015000-ffffff8008016000 4K PTE RW NX SHD AF...
ffffff8008020000-ffffff8008030000 64K PTE RW NX SHD AF...
ffffff8008031000-ffffff8008071000 256K PTE RW NX SHD AF...
ffffff8008080000-ffffff8008200000 1536K PTE ro x SHD AF...
ffffff8008200000-ffffff8008400000 2M PMD ro x SHD AF...
ffffff8008400000-ffffff8008540000 1280K PTE ro x SHD AF...
ffffff8008540000-ffffff8008690000 1344K PTE ro NX SHD AF...
ffffff8008940000-ffffff8008a10000 832K PTE RW NX SHD AF...
ffffff8008aca000-ffffff8008acd000 12K PTE RW NX SHD AF...
ffffffbebffd8000-ffffffbebffdb000 12K PTE RW NX SHD AF...
---[ vmalloc() End ]---
---[ Fixmap start ]---
ffffffbefe800000-ffffffbefea00000 2M PMD ro NX SHD AF...
---[ Fixmap end ]---
---[ PCI I/O start ]---
---[ PCI I/O end ]---
---[ Linear Mapping ]---
ffffffc000000000-ffffffc000080000 512K PTE RW NX SHD AF...
ffffffc000080000-ffffffc000200000 1536K PTE ro NX SHD AF...
ffffffc000200000-ffffffc000600000 4M PMD ro NX SHD AF...
ffffffc000600000-ffffffc000690000 576K PTE ro NX SHD AF...
ffffffc000690000-ffffffc000800000 1472K PTE RW NX SHD AF...
ffffffc000800000-ffffffc002000000 24M PMD RW NX SHD AF...
ffffffc002000000-ffffffc040000000 992M PMD RW NX SHD AF...
ffffffc040000000-ffffffc080000000 1G PGD RW NX SHD AF...
With sysctl kernel.kptr_restrict=2:
cat /sys/kernel/debug/kernel_page_tables
---[ Modules start ]---
---[ Modules end ]---
---[ vmalloc() Area ]---
0000000000000000-0000000000000000 64K PTE RW NX SHD AF...
0000000000000000-0000000000000000 4K PTE RW NX SHD AF...
0000000000000000-0000000000000000 64K PTE RW NX SHD AF...
0000000000000000-0000000000000000 256K PTE RW NX SHD AF...
0000000000000000-0000000000000000 1536K PTE ro x SHD AF...
0000000000000000-0000000000000000 2M PMD ro x SHD AF...
0000000000000000-0000000000000000 1280K PTE ro x SHD AF...
0000000000000000-0000000000000000 1344K PTE ro NX SHD AF...
0000000000000000-0000000000000000 832K PTE RW NX SHD AF...
0000000000000000-0000000000000000 12K PTE RW NX SHD AF...
0000000000000000-0000000000000000 12K PTE RW NX SHD AF...
---[ vmalloc() End ]---
---[ Fixmap start ]---
0000000000000000-0000000000000000 2M PMD ro NX SHD AF...
---[ Fixmap end ]---
---[ PCI I/O start ]---
---[ PCI I/O end ]---
---[ Linear Mapping ]---
0000000000000000-0000000000000000 512K PTE RW NX SHD AF...
0000000000000000-0000000000000000 1536K PTE ro NX SHD AF...
0000000000000000-0000000000000000 4M PMD ro NX SHD AF...
0000000000000000-0000000000000000 576K PTE ro NX SHD AF...
0000000000000000-0000000000000000 1472K PTE RW NX SHD AF...
0000000000000000-0000000000000000 24M PMD RW NX SHD AF...
0000000000000000-0000000000000000 992M PMD RW NX SHD AF...
0000000000000000-0000000000000000 1G PGD RW NX SHD AF...
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
---
arch/arm64/mm/dump.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index ca74a2a..e055ecf 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -253,8 +253,8 @@ static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
if (st->current_prot) {
note_prot_uxn(st, addr);
note_prot_wx(st, addr);
- pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx ",
- st->start_address, addr);
+ pt_dump_seq_printf(st->seq, "%pK-%pK ",
+ (void *)st->start_address, (void *)addr);
delta = (addr - st->start_address) >> 10;
while (!(delta & 1023) && unit[1]) {
--
1.9.1
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| From | Mark Rutland <mark.rutland@arm.com> |
|---|---|
| Date | 2017-02-28 11:30 +0100 |
| Message-ID | <tfNcB-35E-7@gated-at.bofh.it> |
| In reply to | #1589242 |
On Tue, Feb 28, 2017 at 08:42:51AM +0000, Ard Biesheuvel wrote:
> (+ Mark)
(+ Laura)
> On 28 February 2017 at 07:05, Miles Chen <miles.chen@mediatek.com> wrote:
> > Mask kernel pointers of /sys/kernel/debug/kernel_page_tables entry like
> > /proc/vmallocinfo does.
> >
> > With sysctl kernel.kptr_restrict=0 or 1:
> > cat /sys/kernel/debug/kernel_page_tables
>
> I wonder if this file should be accessible at all if kptr_restrict > 0
I don't have strong feelings either way.
This isn't typically enabled, and it's under debugfs, so this shouldn't
be accessible by a typical user anyhow.
That said, there are very few of us who need to take a look at this
file. I'm happy to deal with attacking kptr_restrict when required.
Thanks,
Mark.
> > ---[ Modules start ]---
> > ---[ Modules end ]---
> > ---[ vmalloc() Area ]---
> > ffffff8008000000-ffffff8008010000 64K PTE RW NX SHD AF...
> > ffffff8008015000-ffffff8008016000 4K PTE RW NX SHD AF...
> > ffffff8008020000-ffffff8008030000 64K PTE RW NX SHD AF...
> > ffffff8008031000-ffffff8008071000 256K PTE RW NX SHD AF...
> > ffffff8008080000-ffffff8008200000 1536K PTE ro x SHD AF...
> > ffffff8008200000-ffffff8008400000 2M PMD ro x SHD AF...
> > ffffff8008400000-ffffff8008540000 1280K PTE ro x SHD AF...
> > ffffff8008540000-ffffff8008690000 1344K PTE ro NX SHD AF...
> > ffffff8008940000-ffffff8008a10000 832K PTE RW NX SHD AF...
> > ffffff8008aca000-ffffff8008acd000 12K PTE RW NX SHD AF...
> > ffffffbebffd8000-ffffffbebffdb000 12K PTE RW NX SHD AF...
> > ---[ vmalloc() End ]---
> > ---[ Fixmap start ]---
> > ffffffbefe800000-ffffffbefea00000 2M PMD ro NX SHD AF...
> > ---[ Fixmap end ]---
> > ---[ PCI I/O start ]---
> > ---[ PCI I/O end ]---
> > ---[ Linear Mapping ]---
> > ffffffc000000000-ffffffc000080000 512K PTE RW NX SHD AF...
> > ffffffc000080000-ffffffc000200000 1536K PTE ro NX SHD AF...
> > ffffffc000200000-ffffffc000600000 4M PMD ro NX SHD AF...
> > ffffffc000600000-ffffffc000690000 576K PTE ro NX SHD AF...
> > ffffffc000690000-ffffffc000800000 1472K PTE RW NX SHD AF...
> > ffffffc000800000-ffffffc002000000 24M PMD RW NX SHD AF...
> > ffffffc002000000-ffffffc040000000 992M PMD RW NX SHD AF...
> > ffffffc040000000-ffffffc080000000 1G PGD RW NX SHD AF...
> >
> > With sysctl kernel.kptr_restrict=2:
> > cat /sys/kernel/debug/kernel_page_tables
> > ---[ Modules start ]---
> > ---[ Modules end ]---
> > ---[ vmalloc() Area ]---
> > 0000000000000000-0000000000000000 64K PTE RW NX SHD AF...
> > 0000000000000000-0000000000000000 4K PTE RW NX SHD AF...
> > 0000000000000000-0000000000000000 64K PTE RW NX SHD AF...
> > 0000000000000000-0000000000000000 256K PTE RW NX SHD AF...
> > 0000000000000000-0000000000000000 1536K PTE ro x SHD AF...
> > 0000000000000000-0000000000000000 2M PMD ro x SHD AF...
> > 0000000000000000-0000000000000000 1280K PTE ro x SHD AF...
> > 0000000000000000-0000000000000000 1344K PTE ro NX SHD AF...
> > 0000000000000000-0000000000000000 832K PTE RW NX SHD AF...
> > 0000000000000000-0000000000000000 12K PTE RW NX SHD AF...
> > 0000000000000000-0000000000000000 12K PTE RW NX SHD AF...
> > ---[ vmalloc() End ]---
> > ---[ Fixmap start ]---
> > 0000000000000000-0000000000000000 2M PMD ro NX SHD AF...
> > ---[ Fixmap end ]---
> > ---[ PCI I/O start ]---
> > ---[ PCI I/O end ]---
> > ---[ Linear Mapping ]---
> > 0000000000000000-0000000000000000 512K PTE RW NX SHD AF...
> > 0000000000000000-0000000000000000 1536K PTE ro NX SHD AF...
> > 0000000000000000-0000000000000000 4M PMD ro NX SHD AF...
> > 0000000000000000-0000000000000000 576K PTE ro NX SHD AF...
> > 0000000000000000-0000000000000000 1472K PTE RW NX SHD AF...
> > 0000000000000000-0000000000000000 24M PMD RW NX SHD AF...
> > 0000000000000000-0000000000000000 992M PMD RW NX SHD AF...
> > 0000000000000000-0000000000000000 1G PGD RW NX SHD AF...
> >
> > Signed-off-by: Miles Chen <miles.chen@mediatek.com>
> > ---
> > arch/arm64/mm/dump.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
> > index ca74a2a..e055ecf 100644
> > --- a/arch/arm64/mm/dump.c
> > +++ b/arch/arm64/mm/dump.c
> > @@ -253,8 +253,8 @@ static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
> > if (st->current_prot) {
> > note_prot_uxn(st, addr);
> > note_prot_wx(st, addr);
> > - pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx ",
> > - st->start_address, addr);
> > + pt_dump_seq_printf(st->seq, "%pK-%pK ",
> > + (void *)st->start_address, (void *)addr);
> >
> > delta = (addr - st->start_address) >> 10;
> > while (!(delta & 1023) && unit[1]) {
> > --
> > 1.9.1
> >
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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| From | Will Deacon <will.deacon@arm.com> |
|---|---|
| Date | 2017-03-01 05:00 +0100 |
| Message-ID | <tg3AJ-5wB-1@gated-at.bofh.it> |
| In reply to | #1589341 |
On Tue, Feb 28, 2017 at 02:55:51PM -0800, Laura Abbott wrote: > On 02/28/2017 02:04 AM, Mark Rutland wrote: > > On Tue, Feb 28, 2017 at 08:42:51AM +0000, Ard Biesheuvel wrote: > >> On 28 February 2017 at 07:05, Miles Chen <miles.chen@mediatek.com> wrote: > >>> Mask kernel pointers of /sys/kernel/debug/kernel_page_tables entry like > >>> /proc/vmallocinfo does. > >>> > >>> With sysctl kernel.kptr_restrict=0 or 1: > >>> cat /sys/kernel/debug/kernel_page_tables > >> > >> I wonder if this file should be accessible at all if kptr_restrict > 0 > > > > I don't have strong feelings either way. > > > > This isn't typically enabled, and it's under debugfs, so this shouldn't > > be accessible by a typical user anyhow. > > > > That said, there are very few of us who need to take a look at this > > file. I'm happy to deal with attacking kptr_restrict when required. > > > > In the interest of security it's probably for the best to switch to the > restricted pointer. Who knows what might get enabled or forgotten about. > I don't like the idea of tying enablement of the file to kptr_restrict > though. ... but it's also pretty weird to show the sizes, mapping type and permissions yet hide the virtual addresses. If you want to keep the file in spite of kptr_restrict, which bits are actually useful once the addresses are nobbled? Will
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| From | Ard Biesheuvel <ard.biesheuvel@linaro.org> |
|---|---|
| Date | 2017-02-28 14:00 +0100 |
| Message-ID | <tfNcB-35E-9@gated-at.bofh.it> |
| In reply to | #1589242 |
(+ Mark)
On 28 February 2017 at 07:05, Miles Chen <miles.chen@mediatek.com> wrote:
> Mask kernel pointers of /sys/kernel/debug/kernel_page_tables entry like
> /proc/vmallocinfo does.
>
> With sysctl kernel.kptr_restrict=0 or 1:
> cat /sys/kernel/debug/kernel_page_tables
I wonder if this file should be accessible at all if kptr_restrict > 0
> ---[ Modules start ]---
> ---[ Modules end ]---
> ---[ vmalloc() Area ]---
> ffffff8008000000-ffffff8008010000 64K PTE RW NX SHD AF...
> ffffff8008015000-ffffff8008016000 4K PTE RW NX SHD AF...
> ffffff8008020000-ffffff8008030000 64K PTE RW NX SHD AF...
> ffffff8008031000-ffffff8008071000 256K PTE RW NX SHD AF...
> ffffff8008080000-ffffff8008200000 1536K PTE ro x SHD AF...
> ffffff8008200000-ffffff8008400000 2M PMD ro x SHD AF...
> ffffff8008400000-ffffff8008540000 1280K PTE ro x SHD AF...
> ffffff8008540000-ffffff8008690000 1344K PTE ro NX SHD AF...
> ffffff8008940000-ffffff8008a10000 832K PTE RW NX SHD AF...
> ffffff8008aca000-ffffff8008acd000 12K PTE RW NX SHD AF...
> ffffffbebffd8000-ffffffbebffdb000 12K PTE RW NX SHD AF...
> ---[ vmalloc() End ]---
> ---[ Fixmap start ]---
> ffffffbefe800000-ffffffbefea00000 2M PMD ro NX SHD AF...
> ---[ Fixmap end ]---
> ---[ PCI I/O start ]---
> ---[ PCI I/O end ]---
> ---[ Linear Mapping ]---
> ffffffc000000000-ffffffc000080000 512K PTE RW NX SHD AF...
> ffffffc000080000-ffffffc000200000 1536K PTE ro NX SHD AF...
> ffffffc000200000-ffffffc000600000 4M PMD ro NX SHD AF...
> ffffffc000600000-ffffffc000690000 576K PTE ro NX SHD AF...
> ffffffc000690000-ffffffc000800000 1472K PTE RW NX SHD AF...
> ffffffc000800000-ffffffc002000000 24M PMD RW NX SHD AF...
> ffffffc002000000-ffffffc040000000 992M PMD RW NX SHD AF...
> ffffffc040000000-ffffffc080000000 1G PGD RW NX SHD AF...
>
> With sysctl kernel.kptr_restrict=2:
> cat /sys/kernel/debug/kernel_page_tables
> ---[ Modules start ]---
> ---[ Modules end ]---
> ---[ vmalloc() Area ]---
> 0000000000000000-0000000000000000 64K PTE RW NX SHD AF...
> 0000000000000000-0000000000000000 4K PTE RW NX SHD AF...
> 0000000000000000-0000000000000000 64K PTE RW NX SHD AF...
> 0000000000000000-0000000000000000 256K PTE RW NX SHD AF...
> 0000000000000000-0000000000000000 1536K PTE ro x SHD AF...
> 0000000000000000-0000000000000000 2M PMD ro x SHD AF...
> 0000000000000000-0000000000000000 1280K PTE ro x SHD AF...
> 0000000000000000-0000000000000000 1344K PTE ro NX SHD AF...
> 0000000000000000-0000000000000000 832K PTE RW NX SHD AF...
> 0000000000000000-0000000000000000 12K PTE RW NX SHD AF...
> 0000000000000000-0000000000000000 12K PTE RW NX SHD AF...
> ---[ vmalloc() End ]---
> ---[ Fixmap start ]---
> 0000000000000000-0000000000000000 2M PMD ro NX SHD AF...
> ---[ Fixmap end ]---
> ---[ PCI I/O start ]---
> ---[ PCI I/O end ]---
> ---[ Linear Mapping ]---
> 0000000000000000-0000000000000000 512K PTE RW NX SHD AF...
> 0000000000000000-0000000000000000 1536K PTE ro NX SHD AF...
> 0000000000000000-0000000000000000 4M PMD ro NX SHD AF...
> 0000000000000000-0000000000000000 576K PTE ro NX SHD AF...
> 0000000000000000-0000000000000000 1472K PTE RW NX SHD AF...
> 0000000000000000-0000000000000000 24M PMD RW NX SHD AF...
> 0000000000000000-0000000000000000 992M PMD RW NX SHD AF...
> 0000000000000000-0000000000000000 1G PGD RW NX SHD AF...
>
> Signed-off-by: Miles Chen <miles.chen@mediatek.com>
> ---
> arch/arm64/mm/dump.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
> index ca74a2a..e055ecf 100644
> --- a/arch/arm64/mm/dump.c
> +++ b/arch/arm64/mm/dump.c
> @@ -253,8 +253,8 @@ static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
> if (st->current_prot) {
> note_prot_uxn(st, addr);
> note_prot_wx(st, addr);
> - pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx ",
> - st->start_address, addr);
> + pt_dump_seq_printf(st->seq, "%pK-%pK ",
> + (void *)st->start_address, (void *)addr);
>
> delta = (addr - st->start_address) >> 10;
> while (!(delta & 1023) && unit[1]) {
> --
> 1.9.1
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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