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[79.184.151.107]) by smtp.gmail.com with ESMTPSA id mb9-20020a170906eb0900b0084d34eec68esm7622474ejb.213.2023.01.13.06.56.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Jan 2023 06:56:26 -0800 (PST) From: Jakub Sitnicki To: netdev@vger.kernel.org Cc: kernel-team@cloudflare.com, John Fastabend , Eric Dumazet , Daniel Borkmann , Alexei Starovoitov , Andrii Nakryiko , syzbot+04c21ed96d861dccc5cd@syzkaller.appspotmail.com Subject: [PATCH bpf 1/3] bpf, sockmap: Check for any of tcp_bpf_prots when cloning a listener Date: Fri, 13 Jan 2023 15:56:21 +0100 Message-Id: <20230113-sockmap-fix-v1-1-d3cad092ee10@cloudflare.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230113-sockmap-fix-v1-0-d3cad092ee10@cloudflare.com> References: <20230113-sockmap-fix-v1-0-d3cad092ee10@cloudflare.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net A listening socket linked to a sockmap has its sk_prot overridden. It points to one of the struct proto variants in tcp_bpf_prots. The variant depends on the socket's family and which sockmap programs are attached. A child socket cloned from a TCP listener initially inherits their sk_prot. But before cloning is finished, we restore the child's proto to the listener's original non-tcp_bpf_prots one. This happens in tcp_create_openreq_child -> tcp_bpf_clone. Today, in tcp_bpf_clone we detect if the child's proto should be restored by checking only for the TCP_BPF_BASE proto variant. This is not correct. The sk_prot of listening socket linked to a sockmap can point to to any variant in tcp_bpf_prots. If the listeners sk_prot happens to be not the TCP_BPF_BASE variant, then the child socket unintentionally is left if the inherited sk_prot by tcp_bpf_clone. This leads to issues like infinite recursion on close [1], because the child state is otherwise not set up for use with tcp_bpf_prot operations. Adjust the check in tcp_bpf_clone to detect all of tcp_bpf_prots variants. Note that it wouldn't be sufficient to check the socket state when overriding the sk_prot in tcp_bpf_update_proto in order to always use the TCP_BPF_BASE variant for listening sockets. Since commit b8b8315e39ff ("bpf, sockmap: Remove unhash handler for BPF sockmap usage") it is possible for a socket to transition to TCP_LISTEN state while already linked to a sockmap, e.g. connect() -> insert into map -> connect(AF_UNSPEC) -> listen(). [1]: https://lore.kernel.org/all/00000000000073b14905ef2e7401@google.com/ Fixes: e80251555f0b ("tcp_bpf: Don't let child socket inherit parent protocol ops on copy") Reported-by: syzbot+04c21ed96d861dccc5cd@syzkaller.appspotmail.com Signed-off-by: Jakub Sitnicki --- net/ipv4/tcp_bpf.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index 94aad3870c5f..8db00647e0a4 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -639,10 +639,9 @@ EXPORT_SYMBOL_GPL(tcp_bpf_update_proto); */ void tcp_bpf_clone(const struct sock *sk, struct sock *newsk) { - int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4; struct proto *prot = newsk->sk_prot; - if (prot == &tcp_bpf_prots[family][TCP_BPF_BASE]) + if (tcp_bpf_prots[0] <= prot && prot < tcp_bpf_prots[ARRAY_SIZE(tcp_bpf_prots)]) newsk->sk_prot = sk->sk_prot_creator; } #endif /* CONFIG_BPF_SYSCALL */