linux-kernel - [PATCH net-next 1/2] mctp: handle the struct sockaddr

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 1 Nov 2021 18:54:49 +0100
From:   Eugene Syromiatnikov <esyr@...hat.com>
To:     Jeremy Kerr <jk@...econstruct.com.au>,
        Matt Johnston <matt@...econstruct.com.au>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next 1/2] mctp: handle the struct sockaddr_mctp padding
 fields

In order to have the padding fields actually usable in the future,
there have to be checks that user space doesn't supply non-zero garbage
there.  It is also worth setting these padding fields to zero, unless
it is known that they have been already zeroed.

Cc: stable@...r.kernel.org # v5.15
Complements: 5a20dd46b8b84593 ("mctp: Be explicit about struct sockaddr_mctp padding")
Signed-off-by: Eugene Syromiatnikov <esyr@...hat.com>
---
 net/mctp/af_mctp.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/net/mctp/af_mctp.c b/net/mctp/af_mctp.c
index d344b02..bc88159 100644
--- a/net/mctp/af_mctp.c
+++ b/net/mctp/af_mctp.c
@@ -33,6 +33,12 @@ static int mctp_release(struct socket *sock)
 	return 0;
 }
 
+/* Generic sockaddr checks, padding checks only so far */
+static bool mctp_sockaddr_is_ok(const struct sockaddr_mctp *addr)
+{
+	return !addr->__smctp_pad0 && !addr->__smctp_pad1;
+}
+
 static int mctp_bind(struct socket *sock, struct sockaddr *addr, int addrlen)
 {
 	struct sock *sk = sock->sk;
@@ -52,6 +58,9 @@ static int mctp_bind(struct socket *sock, struct sockaddr *addr, int addrlen)
 	/* it's a valid sockaddr for MCTP, cast and do protocol checks */
 	smctp = (struct sockaddr_mctp *)addr;
 
+	if (!mctp_sockaddr_is_ok(smctp))
+		return -EINVAL;
+
 	lock_sock(sk);
 
 	/* TODO: allow rebind */
@@ -87,6 +96,8 @@ static int mctp_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 			return -EINVAL;
 		if (addr->smctp_family != AF_MCTP)
 			return -EINVAL;
+		if (!mctp_sockaddr_is_ok(addr))
+			return -EINVAL;
 		if (addr->smctp_tag & ~(MCTP_TAG_MASK | MCTP_TAG_OWNER))
 			return -EINVAL;
 
@@ -198,11 +209,13 @@ static int mctp_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 
 		addr = msg->msg_name;
 		addr->smctp_family = AF_MCTP;
+		addr->__smctp_pad0 = 0;
 		addr->smctp_network = cb->net;
 		addr->smctp_addr.s_addr = hdr->src;
 		addr->smctp_type = type;
 		addr->smctp_tag = hdr->flags_seq_tag &
 					(MCTP_HDR_TAG_MASK | MCTP_HDR_FLAG_TO);
+		addr->__smctp_pad1 = 0;
 		msg->msg_namelen = sizeof(*addr);
 
 		if (msk->addr_ext) {
-- 
2.1.4