From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Date: Mon, 13 Mar 2023 12:32:11 +0100
Subject: [PATCH] scm: fix MSG_CTRUNC setting condition for SO_PASSSEC
References: bsc#1012628
Patch-mainline: 6.3.2
Git-commit: a02d83f9947d8f71904eda4de046630c3eb6802c
[ Upstream commit a02d83f9947d8f71904eda4de046630c3eb6802c ]
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" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Leon Romanovsky <leon@kernel.org>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
v2:
- commit message was rewritten according to Eric's suggestion
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
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 1ce365f4..585adc13 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;
--
2.35.3