From: Kees Cook <keescook@chromium.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
"Colin Cross" <ccross@google.com>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Michal Hocko" <mhocko@suse.com>,
"Dave Hansen" <dave.hansen@intel.com>,
"Matthew Wilcox" <willy@infradead.org>,
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"Vlastimil Babka" <vbabka@suse.cz>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Kalesh Singh" <kaleshsingh@google.com>,
"Peter Xu" <peterx@redhat.com>,
rppt@kernel.org, "Peter Zijlstra" <peterz@infradead.org>,
"Catalin Marinas" <catalin.marinas@arm.com>,
vincenzo.frascino@arm.com,
"Chinwen Chang (張錦文)" <chinwen.chang@mediatek.com>,
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"Jens Axboe" <axboe@kernel.dk>,
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"Muchun Song" <songmuchun@bytedance.com>,
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"Thomas Cedeno" <thomascedeno@google.com>,
sashal@kernel.org, cxfcosmos@gmail.com,
"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
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Subject: Re: [PATCH v9 2/3] mm: add a field to store names for private anonymous memory
Date: Fri, 3 Sep 2021 15:28:22 -0700 [thread overview]
Message-ID: <202109031522.ACDF5BA8@keescook> (raw)
In-Reply-To: <CAJuCfpEQAJqu2DLf5D5pCkv4nq+dtVOpiJSnsxwGrgb9H6inQA@mail.gmail.com>
On Fri, Sep 03, 2021 at 02:56:21PM -0700, Suren Baghdasaryan wrote:
> On Fri, Sep 3, 2021 at 2:47 PM Kees Cook <keescook@chromium.org> wrote:
> >
> > (Sorry, a few more things jumped out at me when I looked again...)
> >
> > On Thu, Sep 02, 2021 at 04:18:12PM -0700, Suren Baghdasaryan wrote:
> > > [...]
> > > diff --git a/kernel/sys.c b/kernel/sys.c
> > > index 72c7639e3c98..25118902a376 100644
> > > --- a/kernel/sys.c
> > > +++ b/kernel/sys.c
> > > @@ -2299,6 +2299,64 @@ int __weak arch_prctl_spec_ctrl_set(struct task_struct *t, unsigned long which,
> > >
> > > #define PR_IO_FLUSHER (PF_MEMALLOC_NOIO | PF_LOCAL_THROTTLE)
> > >
> > > +#ifdef CONFIG_MMU
> > > +
> > > +#define ANON_VMA_NAME_MAX_LEN 256
> > > +
> > > +static inline bool is_valid_name_char(char ch)
> > > +{
> > > + /* printable ascii characters, except [ \ ] */
> > > + return (ch > 0x1f && ch < 0x5b) || (ch > 0x5d && ch < 0x7f);
> > > +}
> >
> > In the back of my mind, I feel like disallowing backtick would be nice,
> > but then if $, (, and ) are allowed, it doesn't matter, and that seems
> > too limiting. :)
>
> It's not used by the only current user (Android) and we can always
> allow more chars later. However going the other direction and
> disallowing some of them I think would be harder (need to make sure
> nobody uses them). WDYT if we keep it stricter and relax if needed?
I'd say, if we can also drop each of: ` $ ( )
then let's do it. Better to keep the obvious shell meta-characters out
of this, although I don't feel strongly about it. Anything that might
get confused by this would be similarly confused by binary names too:
$ cat /proc/3407216/maps
560bdafd4000-560bdafd6000 r--p 00000000 fd:02 2621909 /tmp/yay`wat
And it's probably easier to change a binary name than to call prctl. :P
I'm good either way. What you have now is great, but if we wanted to be
extra extra strict, we can add the other 4 above.
--
Kees Cook
next prev parent reply other threads:[~2021-09-03 22:28 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-02 23:18 [PATCH v9 1/3] mm: rearrange madvise code to allow for reuse Suren Baghdasaryan
2021-09-02 23:18 ` [PATCH v9 2/3] mm: add a field to store names for private anonymous memory Suren Baghdasaryan
2021-09-03 21:35 ` Kees Cook
2021-09-03 21:51 ` Suren Baghdasaryan
2021-09-05 13:04 ` Pavel Machek
2021-09-06 15:52 ` Suren Baghdasaryan
2021-09-03 21:47 ` Kees Cook
2021-09-03 21:56 ` Suren Baghdasaryan
2021-09-03 22:28 ` Kees Cook [this message]
2021-10-01 3:44 ` Suren Baghdasaryan
2021-10-01 5:19 ` Kees Cook
2021-09-06 16:55 ` Matthew Wilcox
2021-09-09 4:05 ` Suren Baghdasaryan
2021-09-30 18:56 ` Suren Baghdasaryan
2021-09-30 23:25 ` Kees Cook
2021-10-01 7:01 ` Rasmus Villemoes
2021-10-01 16:34 ` Suren Baghdasaryan
2021-09-02 23:18 ` [PATCH v9 3/3] mm: add anonymous vma name refcounting Suren Baghdasaryan
2021-09-03 22:20 ` Kees Cook
2021-09-03 0:28 ` [PATCH v9 1/3] mm: rearrange madvise code to allow for reuse Suren Baghdasaryan
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