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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Alexander Viro , Jan Kara , Simon Horman , Kuniyuki Iwashima , Willem de Bruijn , linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa Subject: Re: [PATCH 1/2] fs: Add bpf_sock_read_xattr() kfunc to read socket xattrs Message-ID: References: <20260617-work-bpf-sock-xattr-v1-0-a1276f7c9da3@kernel.org> <20260617-work-bpf-sock-xattr-v1-1-a1276f7c9da3@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20260617-work-bpf-sock-xattr-v1-1-a1276f7c9da3@kernel.org> On Wed, Jun 17, 2026 at 01:18:27PM +0200, Christian Brauner wrote: >In c8db08110cbe ("Merge tag 'vfs-7.1-rc1.xattr' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs") >we added support for extended attributes for sockets. This comes in two >flavors: sockfs and non-sockfs/filesystem sockets. Filesystem sockets >are actual filesystem objects so reading xattrs must use dedicated fs >helpers such as bpf_get_dentry_xattr() and bpf_get_file_xattr(). Those >are inherently sleeping operations. Sockfs sockets on the other hand >don't need to use sleeping operations as the underlying data structure >is lockless. In addition, retrieval of sockfs extended attributes often >happens from LSM hooks that only provide struct socket and it's >completely nonsensical to grab a reference to a file, then force a >sleeping operation to retrieve the xattr and drop the reference. We know >that the sockfs file cannot go away while the LSM hook runs. [...] > >Link: https://github.com/systemd/systemd/pull/40559 [1] >Signed-off-by: Christian Brauner (Amutable) >--- Nice this will simplify some of our socket tracking. Reviewed-by: John Fastabend