[PATCH] arm64: dump: hide kernel pointers
From: mark.rutland@arm.com (Mark Rutland)
Date: 2017-02-28 10:29:12
Also in:
linux-mediatek, lkml
On Tue, Feb 28, 2017 at 08:42:51AM +0000, Ard Biesheuvel wrote:
(+ Mark)
(+ Laura)
On 28 February 2017 at 07:05, Miles Chen [off-list ref] wrote:quoted
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_tablesI 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.
quoted
---[ 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 <redacted> --- 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 at lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel