Re: [PATCH v2] [RFC] can: fix msg_namelen values depending on CAN_REQUIRED_SIZE

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Thanks Kurt!

@Marc: Would you suggest to split this patch in two parts (raw, bcm) and (isotp) - as it would simplify the stable process?

isotp emerged in 5.10 while the j1939 (and the CAN_REQUIRED_SIZE macro) existed since 5.4

Regards,
Oliver

On 25.03.21 09:47, Kurt Van Dijck wrote:
Acked-by: Kurt Van Dijck <dev.kurt@xxxxxxxxxxxxxxxxxxxxxx>

On Thu, 25 Mar 2021 09:13:26 +0100, Oliver Hartkopp wrote:
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@xxxxxx/T/#t
Reported-by: Richard Weinberger <richard@xxxxxx>
Suggested-by: Kurt Van Dijck <dev.kurt@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
---
  net/can/bcm.c   | 10 ++++++----
  net/can/isotp.c | 11 +++++++----
  net/can/raw.c   | 14 ++++++++------
  3 files changed, 21 insertions(+), 14 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@xxxxxxxxxxxxx>");
  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/isotp.c b/net/can/isotp.c
index 3ef7f78e553b..86945dbb6c76 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@xxxxxxxxxxxx>");
  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
@@ -987,11 +989,12 @@ 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); @@ -1057,11 +1060,11 @@ 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;
@@ -1153,17 +1156,17 @@ 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)
  {
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@xxxxxxxxxxxxx>");
  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




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