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Mon, 19 Oct 2026 12:40:35 -0700 (PDT) Received: from localhost ([153.61.198.253]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3acc9942956sm7478188a91.1.2026.10.19.12.40.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Oct 2026 12:40:34 -0700 (PDT) Content-Type: text/plain; charset=UTF-8 Date: Mon, 19 Oct 2026 19:40:33 +0000 Message-Id: To: "Michal Luczaj" , "Daniel Borkmann" , "Andrii Nakryiko" , "Eduard Zingerman" , "Kumar Kartikeya Dwivedi" , "Martin KaFai Lau" , "Song Liu" , "Yonghong Song" , "Jiri Olsa" , "Emil Tsalapatis" , "Ihor Solodrai" , "Shuah Khan" , "John Fastabend" , "Lorenz Bauer" Cc: , , , "Sashiko" , "Jakub Sitnicki" Subject: Re: [PATCH bpf-next 2/3] bpf, sockmap: Restrict iter-context sockmap updates to iter/sockmap From: "Alexei Starovoitov" In-Reply-To: References: <20261016-sockmap-update-limit-iter-v1-0-23fa946db59e@rbox.co> <20261016-sockmap-update-limit-iter-v1-2-23fa946db59e@rbox.co> X-Mailer: mkdraft (claude review draft; edit before sending) Content-Transfer-Encoding: 8bit X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 On Mon, Oct 19, 2026 at 08:20 AM Michal Luczaj wrote: > On 10/17/26 01:52, Alexei Starovoitov wrote: >> unix_state_lock() in bpf_iter_unix_seq_show() was added only for >> unix_stream_bpf_update_proto() called from the iter prog. >> iter/unix cannot get there anymore. >> can we drop it ? can be a follow up... > > So we don't care about having a stable socket state while iterating? Which > is the case for iter/sockmap, but is unlike iter/{tcp,udp}. Not sure. Is there a value? > I'm not sure I see the (stream sock) issue above. psock->sk_pair holds the > peer, so peer pointer remains valid during proto update. iter/sockmap is > safe, because sk is held by RCU. And for iter/unix we currently take > unix_state_lock(). got it. you're right. >> Should we restrict it to ctx->sk somehow? > > I recall a discussion about having BPF helpers accept only trusted > pointers: > https://lore.kernel.org/bpf/CAADnVQK_93g_KkNFYXSr8ZvA1fYh4hoFRJCJFPS-zs4ox0HhAA@mail.gmail.com/ > Restricting only iter/unix seems better? we just discussed at bpf sync meeting that it's time to finally remove plain PTR_TO_BTF_ID. Otherwise we keep hitting this bug everywhere. in the meantime can we do it for this one arg ? Mark ctx->sk as PTR_TRUSTED in sock_map_iter_reg like iter/tcp and iter/udp do ?