* [RFC] process /proc/PID/smaps vs /proc/PID/smaps_rollup
@ 2020-09-29 2:05 Sergey Senozhatsky
2020-09-29 2:40 ` Sergey Senozhatsky
0 siblings, 1 reply; 3+ messages in thread
From: Sergey Senozhatsky @ 2020-09-29 2:05 UTC (permalink / raw)
To: Alexey Dobriyan, Andrew Morton, Vlastimil Babka, Kees Cook,
Matthew Wilcox
Cc: linux-kernel, linux-fsdevel, Sergey Senozhatsky
Hello,
One of our unprivileged daemon process needs process PSS info. That
info is usually available in /proc/PID/smaps on per-vma basis, on
in /proc/PID/smaps_rollup as a bunch of accumulated per-vma values.
The latter one is much faster and simpler to get, but, unlike smaps,
smaps_rollup requires PTRACE_MODE_READ, which we don't want to
grant to our unprivileged daemon.
So the question is - can we get, somehow, accumulated PSS info from
a non-privileged process? (Iterating through all process' smaps
vma-s consumes quite a bit of CPU time). This is related to another
question - why do smaps and smaps_rollup have different permission
requirements?
-ss
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC] process /proc/PID/smaps vs /proc/PID/smaps_rollup
2020-09-29 2:05 [RFC] process /proc/PID/smaps vs /proc/PID/smaps_rollup Sergey Senozhatsky
@ 2020-09-29 2:40 ` Sergey Senozhatsky
2022-09-08 9:42 ` Vincent Whitchurch
0 siblings, 1 reply; 3+ messages in thread
From: Sergey Senozhatsky @ 2020-09-29 2:40 UTC (permalink / raw)
To: Alexey Dobriyan, Andrew Morton, Vlastimil Babka, Kees Cook,
Matthew Wilcox
Cc: Sergey Senozhatsky, linux-kernel, linux-fsdevel
On (20/09/29 11:05), Sergey Senozhatsky wrote:
> Hello,
>
> One of our unprivileged daemon process needs process PSS info. That
> info is usually available in /proc/PID/smaps on per-vma basis, on
> in /proc/PID/smaps_rollup as a bunch of accumulated per-vma values.
> The latter one is much faster and simpler to get, but, unlike smaps,
> smaps_rollup requires PTRACE_MODE_READ, which we don't want to
> grant to our unprivileged daemon.
>
> So the question is - can we get, somehow, accumulated PSS info from
> a non-privileged process? (Iterating through all process' smaps
> vma-s consumes quite a bit of CPU time). This is related to another
> question - why do smaps and smaps_rollup have different permission
> requirements?
Hold on, seems that I misread something, /proc/PID/smaps is also
unavailable. So the question is, then, how do we get PSS info of
a random user-space process from an unprivileged daemon?
-ss
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC] process /proc/PID/smaps vs /proc/PID/smaps_rollup
2020-09-29 2:40 ` Sergey Senozhatsky
@ 2022-09-08 9:42 ` Vincent Whitchurch
0 siblings, 0 replies; 3+ messages in thread
From: Vincent Whitchurch @ 2022-09-08 9:42 UTC (permalink / raw)
To: Sergey Senozhatsky
Cc: Alexey Dobriyan, Andrew Morton, Vlastimil Babka, Kees Cook,
Matthew Wilcox, linux-kernel, linux-fsdevel
On Tue, Sep 29, 2020 at 11:40:18AM +0900, Sergey Senozhatsky wrote:
> On (20/09/29 11:05), Sergey Senozhatsky wrote:
> > One of our unprivileged daemon process needs process PSS info. That
> > info is usually available in /proc/PID/smaps on per-vma basis, on
> > in /proc/PID/smaps_rollup as a bunch of accumulated per-vma values.
> > The latter one is much faster and simpler to get, but, unlike smaps,
> > smaps_rollup requires PTRACE_MODE_READ, which we don't want to
> > grant to our unprivileged daemon.
> >
> > So the question is - can we get, somehow, accumulated PSS info from
> > a non-privileged process? (Iterating through all process' smaps
> > vma-s consumes quite a bit of CPU time). This is related to another
> > question - why do smaps and smaps_rollup have different permission
> > requirements?
>
> Hold on, seems that I misread something, /proc/PID/smaps is also
> unavailable. So the question is, then, how do we get PSS info of
> a random user-space process from an unprivileged daemon?
smaps contains a lot of sensitive information, but perhaps smaps_rollup
could be allowed without ptrace rights if the range information is
masked. I've posted a patch here:
https://lore.kernel.org/linux-mm/20220908093919.843346-1-vincent.whitchurch@axis.com/
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-09-08 9:42 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-09-29 2:05 [RFC] process /proc/PID/smaps vs /proc/PID/smaps_rollup Sergey Senozhatsky
2020-09-29 2:40 ` Sergey Senozhatsky
2022-09-08 9:42 ` Vincent Whitchurch
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).