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([2a02:8109:bd40:1414:c91d:59c1:64e:937b]) by smtp.gmail.com with ESMTPSA id r8-20020a50d688000000b004fbf6b35a56sm1351501edi.76.2023.03.13.04.32.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Mar 2023 04:32:34 -0700 (PDT) From: Alexander Mikhalitsyn To: davem@davemloft.net Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Alexander Mikhalitsyn , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Leon Romanovsky Subject: [PATCH net-next v2] scm: fix MSG_CTRUNC setting condition for SO_PASSSEC Date: Mon, 13 Mar 2023 12:32:11 +0100 Message-Id: <20230313113211.178010-1-aleksandr.mikhalitsyn@canonical.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Currently, kernel would set MSG_CTRUNC flag if msg_control buffer wasn't provided and SO_PASSCRED was set or if there was pending SCM_RIGHTS. For some reason we have no corresponding check for SO_PASSSEC. In the recvmsg(2) doc we have: MSG_CTRUNC indicates that some control data was discarded due to lack of space in the buffer for ancillary data. So, we need to set MSG_CTRUNC flag for all types of SCM. This change can break applications those don't check MSG_CTRUNC flag. Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Leon Romanovsky Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Alexander Mikhalitsyn v2: - commit message was rewritten according to Eric's suggestion Acked-by: Paul Moore --- include/net/scm.h | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/include/net/scm.h b/include/net/scm.h index 1ce365f4c256..585adc1346bd 100644 --- a/include/net/scm.h +++ b/include/net/scm.h @@ -105,16 +105,27 @@ static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct sc } } } + +static inline bool scm_has_secdata(struct socket *sock) +{ + return test_bit(SOCK_PASSSEC, &sock->flags); +} #else static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) { } + +static inline bool scm_has_secdata(struct socket *sock) +{ + return false; +} #endif /* CONFIG_SECURITY_NETWORK */ static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm, int flags) { if (!msg->msg_control) { - if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp) + if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp || + scm_has_secdata(sock)) msg->msg_flags |= MSG_CTRUNC; scm_destroy(scm); return;