[PATCH 1/3] can: bcm/raw: fix msg_namelen values depending on CAN_REQUIRED_SIZE

[PATCH 1/3] can: bcm/raw: fix msg_namelen values depending on CAN_REQUIRED_SIZE

[Oliver Hartkopp]

Since commit f5223e9eee65 ("can: extend sockaddr_can to include j1939
members") the sockaddr_can has been extended in size and a new
CAN_REQUIRED_SIZE macro has been introduced to calculate the protocol
specific needed size.

The ABI for the msg_name and msg_namelen has not been adapted to the
new CAN_REQUIRED_SIZE macro for the other CAN protocols which leads
to a problem when an existing binary reads the (increased)
struct sockaddr_can in msg_name.

Fixes: f5223e9eee65 ("can: extend sockaddr_can to include j1939 members")
Link: https://lore.kernel.org/linux-can/1135648123.112255.1616613706554.JavaMail.zimbra@nod.at/T/#t
Reported-by: Richard Weinberger <richard@nod.at>
Tested-by: Richard Weinberger <richard@nod.at>
Acked-by: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 net/can/bcm.c | 10 ++++++----
 net/can/raw.c | 14 ++++++++------
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/net/can/bcm.c b/net/can/bcm.c
index 0e5c37be4a2b..909b9e684e04 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -84,10 +84,12 @@
 MODULE_DESCRIPTION("PF_CAN broadcast manager protocol");
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_AUTHOR("Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
 MODULE_ALIAS("can-proto-2");
 
+#define BCM_MIN_NAMELEN CAN_REQUIRED_SIZE(struct sockaddr_can, can_ifindex)
+
 /*
  * easy access to the first 64 bit of can(fd)_frame payload. cp->data is
  * 64 bit aligned so the offset has to be multiples of 8 which is ensured
  * by the only callers in bcm_rx_cmp_to_index() bcm_rx_handler().
  */
@@ -1290,11 +1292,11 @@ static int bcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 
 	if (!ifindex && msg->msg_name) {
 		/* no bound device as default => check msg_name */
 		DECLARE_SOCKADDR(struct sockaddr_can *, addr, msg->msg_name);
 
-		if (msg->msg_namelen < CAN_REQUIRED_SIZE(*addr, can_ifindex))
+		if (msg->msg_namelen < BCM_MIN_NAMELEN)
 			return -EINVAL;
 
 		if (addr->can_family != AF_CAN)
 			return -EINVAL;
 
@@ -1532,11 +1534,11 @@ static int bcm_connect(struct socket *sock, struct sockaddr *uaddr, int len,
 	struct sock *sk = sock->sk;
 	struct bcm_sock *bo = bcm_sk(sk);
 	struct net *net = sock_net(sk);
 	int ret = 0;
 
-	if (len < CAN_REQUIRED_SIZE(*addr, can_ifindex))
+	if (len < BCM_MIN_NAMELEN)
 		return -EINVAL;
 
 	lock_sock(sk);
 
 	if (bo->bound) {
@@ -1614,12 +1616,12 @@ static int bcm_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 	}
 
 	sock_recv_ts_and_drops(msg, sk, skb);
 
 	if (msg->msg_name) {
-		__sockaddr_check_size(sizeof(struct sockaddr_can));
-		msg->msg_namelen = sizeof(struct sockaddr_can);
+		__sockaddr_check_size(BCM_MIN_NAMELEN);
+		msg->msg_namelen = BCM_MIN_NAMELEN;
 		memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
 	}
 
 	skb_free_datagram(sk, skb);
 
diff --git a/net/can/raw.c b/net/can/raw.c
index 37b47a39a3ed..139d9471ddcf 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -58,10 +58,12 @@
 MODULE_DESCRIPTION("PF_CAN raw protocol");
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>");
 MODULE_ALIAS("can-proto-1");
 
+#define RAW_MIN_NAMELEN CAN_REQUIRED_SIZE(struct sockaddr_can, can_ifindex)
+
 #define MASK_ALL 0
 
 /* A raw socket has a list of can_filters attached to it, each receiving
  * the CAN frames matching that filter.  If the filter list is empty,
  * no CAN frames will be received by the socket.  The default after
@@ -392,11 +394,11 @@ static int raw_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 	struct raw_sock *ro = raw_sk(sk);
 	int ifindex;
 	int err = 0;
 	int notify_enetdown = 0;
 
-	if (len < CAN_REQUIRED_SIZE(*addr, can_ifindex))
+	if (len < RAW_MIN_NAMELEN)
 		return -EINVAL;
 	if (addr->can_family != AF_CAN)
 		return -EINVAL;
 
 	lock_sock(sk);
@@ -473,15 +475,15 @@ static int raw_getname(struct socket *sock, struct sockaddr *uaddr,
 	struct raw_sock *ro = raw_sk(sk);
 
 	if (peer)
 		return -EOPNOTSUPP;
 
-	memset(addr, 0, sizeof(*addr));
+	memset(addr, 0, RAW_MIN_NAMELEN);
 	addr->can_family  = AF_CAN;
 	addr->can_ifindex = ro->ifindex;
 
-	return sizeof(*addr);
+	return RAW_MIN_NAMELEN;
 }
 
 static int raw_setsockopt(struct socket *sock, int level, int optname,
 			  sockptr_t optval, unsigned int optlen)
 {
@@ -737,11 +739,11 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	int err;
 
 	if (msg->msg_name) {
 		DECLARE_SOCKADDR(struct sockaddr_can *, addr, msg->msg_name);
 
-		if (msg->msg_namelen < CAN_REQUIRED_SIZE(*addr, can_ifindex))
+		if (msg->msg_namelen < RAW_MIN_NAMELEN)
 			return -EINVAL;
 
 		if (addr->can_family != AF_CAN)
 			return -EINVAL;
 
@@ -830,12 +832,12 @@ static int raw_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 	}
 
 	sock_recv_ts_and_drops(msg, sk, skb);
 
 	if (msg->msg_name) {
-		__sockaddr_check_size(sizeof(struct sockaddr_can));
-		msg->msg_namelen = sizeof(struct sockaddr_can);
+		__sockaddr_check_size(RAW_MIN_NAMELEN);
+		msg->msg_namelen = RAW_MIN_NAMELEN;
 		memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
 	}
 
 	/* assign the flags that have been recorded in raw_rcv() */
 	msg->msg_flags |= *(raw_flags(skb));
-- 
2.30.2

[PATCH 2/3] can: isotp: fix msg_namelen values depending on CAN_REQUIRED_SIZE

[Oliver Hartkopp]

Since commit f5223e9eee65 ("can: extend sockaddr_can to include j1939
members") the sockaddr_can has been extended in size and a new
CAN_REQUIRED_SIZE macro has been introduced to calculate the protocol
specific needed size.

The ABI for the msg_name and msg_namelen has not been adapted to the
new CAN_REQUIRED_SIZE macro for the other CAN protocols which leads
to a problem when an existing binary reads the (increased)
struct sockaddr_can in msg_name.

Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Link: https://lore.kernel.org/linux-can/1135648123.112255.1616613706554.JavaMail.zimbra@nod.at/T/#t
Reported-by: Richard Weinberger <richard@nod.at>
Acked-by: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 net/can/isotp.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 15ea1234d457..9f94ad3caee9 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -75,10 +75,12 @@
 MODULE_DESCRIPTION("PF_CAN isotp 15765-2:2016 protocol");
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
 MODULE_ALIAS("can-proto-6");
 
+#define ISOTP_MIN_NAMELEN CAN_REQUIRED_SIZE(struct sockaddr_can, can_addr.tp)
+
 #define SINGLE_MASK(id) (((id) & CAN_EFF_FLAG) ? \
 			 (CAN_EFF_MASK | CAN_EFF_FLAG | CAN_RTR_FLAG) : \
 			 (CAN_SFF_MASK | CAN_EFF_FLAG | CAN_RTR_FLAG))
 
 /* ISO 15765-2:2016 supports more than 4095 byte per ISO PDU as the FF_DL can
@@ -984,11 +986,12 @@ static int isotp_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 	}
 
 	sock_recv_timestamp(msg, sk, skb);
 
 	if (msg->msg_name) {
-		msg->msg_namelen = sizeof(struct sockaddr_can);
+		__sockaddr_check_size(ISOTP_MIN_NAMELEN);
+		msg->msg_namelen = ISOTP_MIN_NAMELEN;
 		memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
 	}
 
 	skb_free_datagram(sk, skb);
 
@@ -1054,11 +1057,11 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 	struct net_device *dev;
 	int err = 0;
 	int notify_enetdown = 0;
 	int do_rx_reg = 1;
 
-	if (len < CAN_REQUIRED_SIZE(struct sockaddr_can, can_addr.tp))
+	if (len < ISOTP_MIN_NAMELEN)
 		return -EINVAL;
 
 	/* do not register frame reception for functional addressing */
 	if (so->opt.flags & CAN_ISOTP_SF_BROADCAST)
 		do_rx_reg = 0;
@@ -1150,17 +1153,17 @@ static int isotp_getname(struct socket *sock, struct sockaddr *uaddr, int peer)
 	struct isotp_sock *so = isotp_sk(sk);
 
 	if (peer)
 		return -EOPNOTSUPP;
 
-	memset(addr, 0, sizeof(*addr));
+	memset(addr, 0, ISOTP_MIN_NAMELEN);
 	addr->can_family = AF_CAN;
 	addr->can_ifindex = so->ifindex;
 	addr->can_addr.tp.rx_id = so->rxid;
 	addr->can_addr.tp.tx_id = so->txid;
 
-	return sizeof(*addr);
+	return ISOTP_MIN_NAMELEN;
 }
 
 static int isotp_setsockopt(struct socket *sock, int level, int optname,
 			    sockptr_t optval, unsigned int optlen)
 {
-- 
2.30.2

[PATCH 3/3] can: uapi: can.h: suppress padding of union inside struct can_frame

[Oliver Hartkopp]

In commit ea7800565a12 ("can: add optional DLC element to Classical
CAN frame structure") the struct can_frame::can_dlc was put into an
anonymous union with another u8 variable.

For various reasons some members in struct can_frame and canfd_frame
including the first 8 byes of data are expected to have the same
memory layout. This is enforced by a BUILD_BUG_ON check in af_can.c.

Since the above mentioned commit this check fails on some compilers
(e.g. arm-linux-gnueabi-gcc (GCC) 9.3.0) that apply an alignment on
an (anonymous) union (see Link). Rong Chen analyzed the problem and
found that the union in struct can_frame takes 4 bytes instead of
the expected 1:

| struct can_frame {
|          canid_t                    can_id;               /* 0     4 */
|          union {
|                  __u8               len;                  /* 4     1 */
|                  __u8               can_dlc;              /* 4     1 */
|          };                                               /* 4     4 */
|          __u8                       __pad;                /* 8     1 */
|          __u8                       __res0;               /* 9     1 */
|          __u8                       len8_dlc;             /* 10     1 */
|
|          /* XXX 5 bytes hole, try to pack */
|
|          __u8                       data[8]
| __attribute__((__aligned__(8))); /*    16     8 */
|
|          /* size: 24, cachelines: 1, members: 6 */
|          /* sum members: 19, holes: 1, sum holes: 5 */
|          /* forced alignments: 1, forced holes: 1, sum forced holes: 5 */
|          /* last cacheline: 24 bytes */
| } __attribute__((__aligned__(8)));

Marking the anonymous union as __attribute__((packed)) fixes the
BUILD_BUG_ON problem on these compilers.

Fixes: ea7800565a12 ("can: add optional DLC element to Classical CAN frame structure")
Link: https://lore.kernel.org/linux-can/2c82ec23-3551-61b5-1bd8-178c3407ee83@hartkopp.net/
Suggested-by: Rong Chen <rong.a.chen@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Author: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 include/uapi/linux/can.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/uapi/linux/can.h b/include/uapi/linux/can.h
index f75238ac6dce..56abe9b50561 100644
--- a/include/uapi/linux/can.h
+++ b/include/uapi/linux/can.h
@@ -111,11 +111,11 @@ struct can_frame {
 		 * was previously named can_dlc so we need to carry that
 		 * name for legacy support
 		 */
 		__u8 len;
 		__u8 can_dlc; /* deprecated */
-	};
+	} __attribute__((packed)); /* disable padding by some compilers */
 	__u8 __pad; /* padding */
 	__u8 __res0; /* reserved / padding */
 	__u8 len8_dlc; /* optional DLC for 8 byte payload length (9 .. 15) */
 	__u8 data[CAN_MAX_DLEN] __attribute__((aligned(8)));
 };
-- 
2.30.2