From: Christoph Hellwig <hch@infradead.org>
To: Christian Brauner <brauner@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
bpf@vger.kernel.org, KP Singh <kpsingh@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] bpf: classify block device hooks appropriately
Date: Fri, 20 Feb 2026 10:28:24 -0800 [thread overview]
Message-ID: <aZinyCqhKYSFLj43@infradead.org> (raw)
In-Reply-To: <20260220-work-bpf-bdev-v1-1-c53e852c4702@kernel.org>
On Fri, Feb 20, 2026 at 06:48:48PM +0100, Christian Brauner wrote:
> A bunch of new hooks for managing block devices were added a while ago
> but they weren't actually appropriately classified.
>
> * bpf_lsm_bdev_alloc() is called when the inode for the block
> device is allocated. This happens from a sleepable context so mark the
> function as sleepable. When this function is called the memory for the
> block device storage embedded into the inode is zeroed. That block
> device cannot be meaningfully reference or interacted with at this
> point. So mark it as untrusted for now.
>
> * bpf_lsm_bdev_free() is called when the inode for the block
> device is freed. A bunch of memory associated with the block device
> has already been freed and there's dangling pointers in there. So mark
> it as untrusted. It cannot be meaningfully referenced or interacted
> with anymore. It is also called from sb->s_op->free_inode:: which
> means it runs in rcu context (most of the times). So leave it as
> non-sleepable.
How did this even get added? None of this should be of any business
to LSM hooks :(
next prev parent reply other threads:[~2026-02-20 18:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-20 17:48 [PATCH 0/2] bpf: classify block device hooks and add selftests Christian Brauner
2026-02-20 17:48 ` [PATCH 1/2] bpf: classify block device hooks appropriately Christian Brauner
2026-02-20 18:28 ` Christoph Hellwig [this message]
2026-02-23 13:42 ` Christian Brauner
2026-02-20 17:48 ` [PATCH 2/2] selftests/bpf: add block device management selftests Christian Brauner
2026-03-23 14:22 ` [PATCH 0/2] bpf: classify block device hooks and add selftests Christian Brauner
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