* [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry
@ 2018-04-08 3:37 Huang, Ying
2018-04-10 0:47 ` Andrew Morton
2018-04-10 1:28 ` Huang, Ying
0 siblings, 2 replies; 9+ messages in thread
From: Huang, Ying @ 2018-04-08 3:37 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, linux-kernel, Huang Ying, Michal Hocko,
Kirill A. Shutemov, Andrei Vagin, Dan Williams, Jerome Glisse,
Daniel Colascione, Zi Yan, Naoya Horiguchi
From: Huang Ying <ying.huang@intel.com>
The swap offset reported by /proc/<pid>/pagemap may be not correct for
PMD migration entry. If addr passed into pagemap_range() isn't
aligned with PMD start address, the swap offset reported doesn't
reflect this. And in the loop to report information of each sub-page,
the swap offset isn't increased accordingly as that for PFN.
BTW: migration swap entries have PFN information, do we need to
restrict whether to show them?
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrei Vagin <avagin@openvz.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: "Jerome Glisse" <jglisse@redhat.com>
Cc: Daniel Colascione <dancol@google.com>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
fs/proc/task_mmu.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 65ae54659833..757e748da613 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1310,9 +1310,11 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
else if (is_swap_pmd(pmd)) {
swp_entry_t entry = pmd_to_swp_entry(pmd);
+ unsigned long offset = swp_offset(entry);
+ offset += (addr & ~PMD_MASK) >> PAGE_SHIFT;
frame = swp_type(entry) |
- (swp_offset(entry) << MAX_SWAPFILES_SHIFT);
+ (offset << MAX_SWAPFILES_SHIFT);
flags |= PM_SWAP;
if (pmd_swp_soft_dirty(pmd))
flags |= PM_SOFT_DIRTY;
@@ -1332,6 +1334,8 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
break;
if (pm->show_pfn && (flags & PM_PRESENT))
frame++;
+ else if (flags | PM_SWAP)
+ frame += (1 << MAX_SWAPFILES_SHIFT);
}
spin_unlock(ptl);
return err;
--
2.15.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry
2018-04-08 3:37 [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry Huang, Ying
@ 2018-04-10 0:47 ` Andrew Morton
2018-04-10 0:57 ` Huang, Ying
2018-04-10 1:28 ` Huang, Ying
1 sibling, 1 reply; 9+ messages in thread
From: Andrew Morton @ 2018-04-10 0:47 UTC (permalink / raw)
To: Huang, Ying
Cc: linux-mm, linux-kernel, Michal Hocko, Kirill A. Shutemov,
Andrei Vagin, Dan Williams, Jerome Glisse, Daniel Colascione,
Zi Yan, Naoya Horiguchi
On Sun, 8 Apr 2018 11:37:37 +0800 "Huang, Ying" <ying.huang@intel.com> wrote:
> From: Huang Ying <ying.huang@intel.com>
>
> The swap offset reported by /proc/<pid>/pagemap may be not correct for
> PMD migration entry. If addr passed into pagemap_range() isn't
pagemap_pmd_range(), yes?
> aligned with PMD start address,
How can this situation come about?
> the swap offset reported doesn't
> reflect this. And in the loop to report information of each sub-page,
> the swap offset isn't increased accordingly as that for PFN.
>
> BTW: migration swap entries have PFN information, do we need to
> restrict whether to show them?
For what reason? Address obfuscation?
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry
2018-04-10 0:47 ` Andrew Morton
@ 2018-04-10 0:57 ` Huang, Ying
0 siblings, 0 replies; 9+ messages in thread
From: Huang, Ying @ 2018-04-10 0:57 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, linux-kernel, Michal Hocko, Kirill A. Shutemov,
Andrei Vagin, Dan Williams, Jerome Glisse, Daniel Colascione,
Zi Yan, Naoya Horiguchi
Andrew Morton <akpm@linux-foundation.org> writes:
> On Sun, 8 Apr 2018 11:37:37 +0800 "Huang, Ying" <ying.huang@intel.com> wrote:
>
>> From: Huang Ying <ying.huang@intel.com>
>>
>> The swap offset reported by /proc/<pid>/pagemap may be not correct for
>> PMD migration entry. If addr passed into pagemap_range() isn't
>
> pagemap_pmd_range(), yes?
Yes. Sorry for typo.
>> aligned with PMD start address,
>
> How can this situation come about?
After open /proc/<pid>/pagemap, if user seeks to a page whose address
doesn't aligned with PMD start address. I have verified this with a
simple test program.
>> the swap offset reported doesn't
>> reflect this. And in the loop to report information of each sub-page,
>> the swap offset isn't increased accordingly as that for PFN.
>>
>> BTW: migration swap entries have PFN information, do we need to
>> restrict whether to show them?
>
> For what reason? Address obfuscation?
This is an existing feature for PFN report of /proc/<pid>/pagemap,
reason is in following commit log. I am wondering whether that is
necessary for migration swap entries too.
ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce
Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
AuthorDate: Mon Mar 9 23:11:12 2015 +0200
Commit: Linus Torvalds <torvalds@linux-foundation.org>
CommitDate: Tue Mar 17 09:31:30 2015 -0700
pagemap: do not leak physical addresses to non-privileged userspace
As pointed by recent post[1] on exploiting DRAM physical imperfection,
/proc/PID/pagemap exposes sensitive information which can be used to do
attacks.
This disallows anybody without CAP_SYS_ADMIN to read the pagemap.
[1] http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html
[ Eventually we might want to do anything more finegrained, but for now
this is the simple model. - Linus ]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Seaborn <mseaborn@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Best Regards,
Huang, Ying
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry
@ 2018-04-10 0:57 ` Huang, Ying
0 siblings, 0 replies; 9+ messages in thread
From: Huang, Ying @ 2018-04-10 0:57 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, linux-kernel, Michal Hocko, Kirill A. Shutemov,
Andrei Vagin, Dan Williams, Jerome Glisse, Daniel Colascione,
Zi Yan, Naoya Horiguchi
Andrew Morton <akpm@linux-foundation.org> writes:
> On Sun, 8 Apr 2018 11:37:37 +0800 "Huang, Ying" <ying.huang@intel.com> wrote:
>
>> From: Huang Ying <ying.huang@intel.com>
>>
>> The swap offset reported by /proc/<pid>/pagemap may be not correct for
>> PMD migration entry. If addr passed into pagemap_range() isn't
>
> pagemap_pmd_range(), yes?
Yes. Sorry for typo.
>> aligned with PMD start address,
>
> How can this situation come about?
After open /proc/<pid>/pagemap, if user seeks to a page whose address
doesn't aligned with PMD start address. I have verified this with a
simple test program.
>> the swap offset reported doesn't
>> reflect this. And in the loop to report information of each sub-page,
>> the swap offset isn't increased accordingly as that for PFN.
>>
>> BTW: migration swap entries have PFN information, do we need to
>> restrict whether to show them?
>
> For what reason? Address obfuscation?
This is an existing feature for PFN report of /proc/<pid>/pagemap,
reason is in following commit log. I am wondering whether that is
necessary for migration swap entries too.
ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce
Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
AuthorDate: Mon Mar 9 23:11:12 2015 +0200
Commit: Linus Torvalds <torvalds@linux-foundation.org>
CommitDate: Tue Mar 17 09:31:30 2015 -0700
pagemap: do not leak physical addresses to non-privileged userspace
As pointed by recent post[1] on exploiting DRAM physical imperfection,
/proc/PID/pagemap exposes sensitive information which can be used to do
attacks.
This disallows anybody without CAP_SYS_ADMIN to read the pagemap.
[1] http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html
[ Eventually we might want to do anything more finegrained, but for now
this is the simple model. - Linus ]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Seaborn <mseaborn@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Best Regards,
Huang, Ying
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry
2018-04-08 3:37 [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry Huang, Ying
@ 2018-04-10 1:28 ` Huang, Ying
2018-04-10 1:28 ` Huang, Ying
1 sibling, 0 replies; 9+ messages in thread
From: Huang, Ying @ 2018-04-10 1:28 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, linux-kernel, Michal Hocko, Kirill A. Shutemov,
Andrei Vagin, Dan Williams, Jerome Glisse, Daniel Colascione,
Zi Yan, Naoya Horiguchi
Hi, Andrew,
"Huang, Ying" <ying.huang@intel.com> writes:
> From: Huang Ying <ying.huang@intel.com>
>
> The swap offset reported by /proc/<pid>/pagemap may be not correct for
> PMD migration entry. If addr passed into pagemap_range() isn't
> aligned with PMD start address, the swap offset reported doesn't
> reflect this. And in the loop to report information of each sub-page,
> the swap offset isn't increased accordingly as that for PFN.
>
> BTW: migration swap entries have PFN information, do we need to
> restrict whether to show them?
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> Cc: Andrei Vagin <avagin@openvz.org>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: "Jerome Glisse" <jglisse@redhat.com>
> Cc: Daniel Colascione <dancol@google.com>
> Cc: Zi Yan <zi.yan@cs.rutgers.edu>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> ---
> fs/proc/task_mmu.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 65ae54659833..757e748da613 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -1310,9 +1310,11 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
> #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
> else if (is_swap_pmd(pmd)) {
> swp_entry_t entry = pmd_to_swp_entry(pmd);
> + unsigned long offset = swp_offset(entry);
>
> + offset += (addr & ~PMD_MASK) >> PAGE_SHIFT;
> frame = swp_type(entry) |
> - (swp_offset(entry) << MAX_SWAPFILES_SHIFT);
> + (offset << MAX_SWAPFILES_SHIFT);
> flags |= PM_SWAP;
> if (pmd_swp_soft_dirty(pmd))
> flags |= PM_SOFT_DIRTY;
> @@ -1332,6 +1334,8 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
> break;
> if (pm->show_pfn && (flags & PM_PRESENT))
> frame++;
> + else if (flags | PM_SWAP)
Oops, I just found a typo here, it should be,
+ else if (flags & PM_SWAP)
Sorry about that. Do I need to refresh the patch or you will fix it
inline?
Best Regards,
Huang, Ying
> + frame += (1 << MAX_SWAPFILES_SHIFT);
> }
> spin_unlock(ptl);
> return err;
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry
@ 2018-04-10 1:28 ` Huang, Ying
0 siblings, 0 replies; 9+ messages in thread
From: Huang, Ying @ 2018-04-10 1:28 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, linux-kernel, Michal Hocko, Kirill A. Shutemov,
Andrei Vagin, Dan Williams, Jerome Glisse, Daniel Colascione,
Zi Yan, Naoya Horiguchi
Hi, Andrew,
"Huang, Ying" <ying.huang@intel.com> writes:
> From: Huang Ying <ying.huang@intel.com>
>
> The swap offset reported by /proc/<pid>/pagemap may be not correct for
> PMD migration entry. If addr passed into pagemap_range() isn't
> aligned with PMD start address, the swap offset reported doesn't
> reflect this. And in the loop to report information of each sub-page,
> the swap offset isn't increased accordingly as that for PFN.
>
> BTW: migration swap entries have PFN information, do we need to
> restrict whether to show them?
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> Cc: Andrei Vagin <avagin@openvz.org>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: "Jerome Glisse" <jglisse@redhat.com>
> Cc: Daniel Colascione <dancol@google.com>
> Cc: Zi Yan <zi.yan@cs.rutgers.edu>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> ---
> fs/proc/task_mmu.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 65ae54659833..757e748da613 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -1310,9 +1310,11 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
> #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
> else if (is_swap_pmd(pmd)) {
> swp_entry_t entry = pmd_to_swp_entry(pmd);
> + unsigned long offset = swp_offset(entry);
>
> + offset += (addr & ~PMD_MASK) >> PAGE_SHIFT;
> frame = swp_type(entry) |
> - (swp_offset(entry) << MAX_SWAPFILES_SHIFT);
> + (offset << MAX_SWAPFILES_SHIFT);
> flags |= PM_SWAP;
> if (pmd_swp_soft_dirty(pmd))
> flags |= PM_SOFT_DIRTY;
> @@ -1332,6 +1334,8 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
> break;
> if (pm->show_pfn && (flags & PM_PRESENT))
> frame++;
> + else if (flags | PM_SWAP)
Oops, I just found a typo here, it should be,
+ else if (flags & PM_SWAP)
Sorry about that. Do I need to refresh the patch or you will fix it
inline?
Best Regards,
Huang, Ying
> + frame += (1 << MAX_SWAPFILES_SHIFT);
> }
> spin_unlock(ptl);
> return err;
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry
2018-04-10 0:57 ` Huang, Ying
(?)
@ 2018-04-10 11:12 ` Kirill A. Shutemov
2018-04-11 0:56 ` Huang, Ying
-1 siblings, 1 reply; 9+ messages in thread
From: Kirill A. Shutemov @ 2018-04-10 11:12 UTC (permalink / raw)
To: Huang, Ying
Cc: Andrew Morton, linux-mm, linux-kernel, Michal Hocko,
Kirill A. Shutemov, Andrei Vagin, Dan Williams, Jerome Glisse,
Daniel Colascione, Zi Yan, Naoya Horiguchi
On Tue, Apr 10, 2018 at 08:57:19AM +0800, Huang, Ying wrote:
> >> the swap offset reported doesn't
> >> reflect this. And in the loop to report information of each sub-page,
> >> the swap offset isn't increased accordingly as that for PFN.
> >>
> >> BTW: migration swap entries have PFN information, do we need to
> >> restrict whether to show them?
> >
> > For what reason? Address obfuscation?
>
> This is an existing feature for PFN report of /proc/<pid>/pagemap,
> reason is in following commit log. I am wondering whether that is
> necessary for migration swap entries too.
>
> ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce
> Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> AuthorDate: Mon Mar 9 23:11:12 2015 +0200
> Commit: Linus Torvalds <torvalds@linux-foundation.org>
> CommitDate: Tue Mar 17 09:31:30 2015 -0700
>
> pagemap: do not leak physical addresses to non-privileged userspace
>
> As pointed by recent post[1] on exploiting DRAM physical imperfection,
> /proc/PID/pagemap exposes sensitive information which can be used to do
> attacks.
>
> This disallows anybody without CAP_SYS_ADMIN to read the pagemap.
>
> [1] http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html
>
> [ Eventually we might want to do anything more finegrained, but for now
> this is the simple model. - Linus ]
Note that there's follow up to the commit:
1c90308e7a77 ("pagemap: hide physical addresses from non-privileged users")
It introduces pm->show_pfn and it should be applied to swap entries too.
--
Kirill A. Shutemov
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry
2018-04-10 11:12 ` Kirill A. Shutemov
@ 2018-04-11 0:56 ` Huang, Ying
0 siblings, 0 replies; 9+ messages in thread
From: Huang, Ying @ 2018-04-11 0:56 UTC (permalink / raw)
To: Kirill A. Shutemov
Cc: Andrew Morton, linux-mm, linux-kernel, Michal Hocko,
Kirill A. Shutemov, Andrei Vagin, Dan Williams, Jerome Glisse,
Daniel Colascione, Zi Yan, Naoya Horiguchi
"Kirill A. Shutemov" <kirill@shutemov.name> writes:
> On Tue, Apr 10, 2018 at 08:57:19AM +0800, Huang, Ying wrote:
>> >> the swap offset reported doesn't
>> >> reflect this. And in the loop to report information of each sub-page,
>> >> the swap offset isn't increased accordingly as that for PFN.
>> >>
>> >> BTW: migration swap entries have PFN information, do we need to
>> >> restrict whether to show them?
>> >
>> > For what reason? Address obfuscation?
>>
>> This is an existing feature for PFN report of /proc/<pid>/pagemap,
>> reason is in following commit log. I am wondering whether that is
>> necessary for migration swap entries too.
>>
>> ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce
>> Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>> AuthorDate: Mon Mar 9 23:11:12 2015 +0200
>> Commit: Linus Torvalds <torvalds@linux-foundation.org>
>> CommitDate: Tue Mar 17 09:31:30 2015 -0700
>>
>> pagemap: do not leak physical addresses to non-privileged userspace
>>
>> As pointed by recent post[1] on exploiting DRAM physical imperfection,
>> /proc/PID/pagemap exposes sensitive information which can be used to do
>> attacks.
>>
>> This disallows anybody without CAP_SYS_ADMIN to read the pagemap.
>>
>> [1] http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html
>>
>> [ Eventually we might want to do anything more finegrained, but for now
>> this is the simple model. - Linus ]
>
> Note that there's follow up to the commit:
>
> 1c90308e7a77 ("pagemap: hide physical addresses from non-privileged users")
>
> It introduces pm->show_pfn and it should be applied to swap entries too.
So you think we should hide all swap entry information if
(!pm->show_pfn) regardless they are migration swap entries or not?
Best Regards,
Huang, Ying
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry
@ 2018-04-11 0:56 ` Huang, Ying
0 siblings, 0 replies; 9+ messages in thread
From: Huang, Ying @ 2018-04-11 0:56 UTC (permalink / raw)
To: Kirill A. Shutemov
Cc: Andrew Morton, linux-mm, linux-kernel, Michal Hocko,
Kirill A. Shutemov, Andrei Vagin, Dan Williams, Jerome Glisse,
Daniel Colascione, Zi Yan, Naoya Horiguchi
"Kirill A. Shutemov" <kirill@shutemov.name> writes:
> On Tue, Apr 10, 2018 at 08:57:19AM +0800, Huang, Ying wrote:
>> >> the swap offset reported doesn't
>> >> reflect this. And in the loop to report information of each sub-page,
>> >> the swap offset isn't increased accordingly as that for PFN.
>> >>
>> >> BTW: migration swap entries have PFN information, do we need to
>> >> restrict whether to show them?
>> >
>> > For what reason? Address obfuscation?
>>
>> This is an existing feature for PFN report of /proc/<pid>/pagemap,
>> reason is in following commit log. I am wondering whether that is
>> necessary for migration swap entries too.
>>
>> ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce
>> Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>> AuthorDate: Mon Mar 9 23:11:12 2015 +0200
>> Commit: Linus Torvalds <torvalds@linux-foundation.org>
>> CommitDate: Tue Mar 17 09:31:30 2015 -0700
>>
>> pagemap: do not leak physical addresses to non-privileged userspace
>>
>> As pointed by recent post[1] on exploiting DRAM physical imperfection,
>> /proc/PID/pagemap exposes sensitive information which can be used to do
>> attacks.
>>
>> This disallows anybody without CAP_SYS_ADMIN to read the pagemap.
>>
>> [1] http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html
>>
>> [ Eventually we might want to do anything more finegrained, but for now
>> this is the simple model. - Linus ]
>
> Note that there's follow up to the commit:
>
> 1c90308e7a77 ("pagemap: hide physical addresses from non-privileged users")
>
> It introduces pm->show_pfn and it should be applied to swap entries too.
So you think we should hide all swap entry information if
(!pm->show_pfn) regardless they are migration swap entries or not?
Best Regards,
Huang, Ying
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2018-04-11 0:57 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-04-08 3:37 [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry Huang, Ying
2018-04-10 0:47 ` Andrew Morton
2018-04-10 0:57 ` Huang, Ying
2018-04-10 0:57 ` Huang, Ying
2018-04-10 11:12 ` Kirill A. Shutemov
2018-04-11 0:56 ` Huang, Ying
2018-04-11 0:56 ` Huang, Ying
2018-04-10 1:28 ` Huang, Ying
2018-04-10 1:28 ` Huang, Ying
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