From: Kees Cook <keescook@chromium.org>
To: Kalesh Singh <kaleshsingh@google.com>
Cc: jannh@google.com, jeffv@google.com, surenb@google.com,
minchan@kernel.org, hridya@google.com, rdunlap@infradead.org,
christian.koenig@amd.com, willy@infradead.org,
viro@zeniv.linux.org.uk, kernel-team@android.com,
Alexey Dobriyan <adobriyan@gmail.com>,
Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
Michal Hocko <mhocko@suse.com>,
Alexey Gladkov <gladkov.alexey@gmail.com>,
Szabolcs Nagy <szabolcs.nagy@arm.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Christian Brauner <christian.brauner@ubuntu.com>,
Michel Lespinasse <walken@google.com>,
Bernd Edlinger <bernd.edlinger@hotmail.de>,
Andrei Vagin <avagin@gmail.com>, Helge Deller <deller@gmx.de>,
James Morris <jamorris@linux.microsoft.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-doc@vger.kernel.org
Subject: Re: [RESEND PATCH v6 1/2] procfs: Allow reading fdinfo with PTRACE_MODE_READ
Date: Wed, 17 Mar 2021 22:55:22 -0700 [thread overview]
Message-ID: <202103172255.46B192DA@keescook> (raw)
In-Reply-To: <20210308170651.919148-1-kaleshsingh@google.com>
On Mon, Mar 08, 2021 at 05:06:40PM +0000, Kalesh Singh wrote:
> Android captures per-process system memory state when certain low memory
> events (e.g a foreground app kill) occur, to identify potential memory
> hoggers. In order to measure how much memory a process actually consumes,
> it is necessary to include the DMA buffer sizes for that process in the
> memory accounting. Since the handle to DMA buffers are raw FDs, it is
> important to be able to identify which processes have FD references to
> a DMA buffer.
>
> Currently, DMA buffer FDs can be accounted using /proc/<pid>/fd/* and
> /proc/<pid>/fdinfo -- both are only readable by the process owner,
> as follows:
> 1. Do a readlink on each FD.
> 2. If the target path begins with "/dmabuf", then the FD is a dmabuf FD.
> 3. stat the file to get the dmabuf inode number.
> 4. Read/ proc/<pid>/fdinfo/<fd>, to get the DMA buffer size.
>
> Accessing other processes' fdinfo requires root privileges. This limits
> the use of the interface to debugging environments and is not suitable
> for production builds. Granting root privileges even to a system process
> increases the attack surface and is highly undesirable.
>
> Since fdinfo doesn't permit reading process memory and manipulating
> process state, allow accessing fdinfo under PTRACE_MODE_READ_FSCRED.
>
> Suggested-by: Jann Horn <jannh@google.com>
> Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Who would be best to pick this up? Maybe akpm?
--
Kees Cook
next prev parent reply other threads:[~2021-03-18 5:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-08 17:06 [RESEND PATCH v6 1/2] procfs: Allow reading fdinfo with PTRACE_MODE_READ Kalesh Singh
2021-03-08 17:06 ` [RESEND PATCH v6 2/2] procfs/dmabuf: Add inode number to /proc/*/fdinfo Kalesh Singh
2021-03-18 5:54 ` Kees Cook
2021-03-08 17:54 ` [RESEND PATCH v6 1/2] procfs: Allow reading fdinfo with PTRACE_MODE_READ Christian König
2021-03-08 18:06 ` Kalesh Singh
2021-03-18 5:55 ` Kees Cook [this message]
2021-03-18 6:14 ` Kalesh Singh
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