From patchwork Fri Jul 21 15:59:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 13322440 X-Patchwork-Delegate: kuba@kernel.org Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3C46C1ED41; Fri, 21 Jul 2023 18:54:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6487CC433C7; Fri, 21 Jul 2023 18:54:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689965664; bh=zALDhhySGfyIUT3OC9NQC7z1i6nfr0e+GfPKJzNbJYM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VaTfxityQRMjDTGuByuiUJrpEaUNks9HMVTBz6oIQvj6Gip8p8Hu7BLYhmbMoXzQb AqAZf2X/WwrGUAAP4xovtJZkCjoDOaiX2VBygkT++z3jV/H+qKiEOwnxWZPsIWB451 zK8oUzG62l7dZCeCNio/K+4z5IrCciep7NiJq+BE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Daniel Borkmann , Christian Brauner , Stanislav Fomichev , Neil Horman , Marcelo Ricardo Leitner , Xin Long , linux-sctp@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Alexander Mikhalitsyn , "David S. Miller" , Sasha Levin Subject: [PATCH 5.15 042/532] sctp: add bpf_bypass_getsockopt proto callback Date: Fri, 21 Jul 2023 17:59:06 +0200 Message-ID: <20230721160616.927524288@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230721160614.695323302@linuxfoundation.org> References: <20230721160614.695323302@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org From: Alexander Mikhalitsyn [ Upstream commit 2598619e012cee5273a2821441b9a051ad931249 ] Implement ->bpf_bypass_getsockopt proto callback and filter out SCTP_SOCKOPT_PEELOFF, SCTP_SOCKOPT_PEELOFF_FLAGS and SCTP_SOCKOPT_CONNECTX3 socket options from running eBPF hook on them. SCTP_SOCKOPT_PEELOFF and SCTP_SOCKOPT_PEELOFF_FLAGS options do fd_install(), and if BPF_CGROUP_RUN_PROG_GETSOCKOPT hook returns an error after success of the original handler sctp_getsockopt(...), userspace will receive an error from getsockopt syscall and will be not aware that fd was successfully installed into a fdtable. As pointed by Marcelo Ricardo Leitner it seems reasonable to skip bpf getsockopt hook for SCTP_SOCKOPT_CONNECTX3 sockopt too. Because internaly, it triggers connect() and if error is masked then userspace will be confused. This patch was born as a result of discussion around a new SCM_PIDFD interface: https://lore.kernel.org/all/20230413133355.350571-3-aleksandr.mikhalitsyn@canonical.com/ Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks") Cc: Daniel Borkmann Cc: Christian Brauner Cc: Stanislav Fomichev Cc: Neil Horman Cc: Marcelo Ricardo Leitner Cc: Xin Long Cc: linux-sctp@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org Suggested-by: Stanislav Fomichev Acked-by: Stanislav Fomichev Signed-off-by: Alexander Mikhalitsyn Acked-by: Xin Long Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/sctp/socket.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 2bbc81ddb9e08..ed35d4a4c5253 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -8287,6 +8287,22 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname, return retval; } +static bool sctp_bpf_bypass_getsockopt(int level, int optname) +{ + if (level == SOL_SCTP) { + switch (optname) { + case SCTP_SOCKOPT_PEELOFF: + case SCTP_SOCKOPT_PEELOFF_FLAGS: + case SCTP_SOCKOPT_CONNECTX3: + return true; + default: + return false; + } + } + + return false; +} + static int sctp_hash(struct sock *sk) { /* STUB */ @@ -9655,6 +9671,7 @@ struct proto sctp_prot = { .shutdown = sctp_shutdown, .setsockopt = sctp_setsockopt, .getsockopt = sctp_getsockopt, + .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt, .sendmsg = sctp_sendmsg, .recvmsg = sctp_recvmsg, .bind = sctp_bind, @@ -9707,6 +9724,7 @@ struct proto sctpv6_prot = { .shutdown = sctp_shutdown, .setsockopt = sctp_setsockopt, .getsockopt = sctp_getsockopt, + .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt, .sendmsg = sctp_sendmsg, .recvmsg = sctp_recvmsg, .bind = sctp_bind,