pull-request: can 2020-08-14

pull-request: can 2020-08-14

[Marc Kleine-Budde]

Hello David,

this is a pull request of 6 patches for net/master. All patches fix problems in
the j1939 CAN networking stack.

The first patch is by Eric Dumazet fixes a kernel-infoleak in
j1939_sk_sock2sockaddr_can().

The remaining 5 patches are by Oleksij Rempel and fix recption of j1939
messages not orginated by the stack, a use-after-free in j1939_tp_txtimer(),
ensure that the CAN driver has a ml_priv allocated. These problem were found by
google's syzbot. Further ETP sessions with block size of less than 255 are
fixed and a sanity check was added to j1939_xtp_rx_dat_one() to detect packet
corruption.

regards,
Marc

---

The following changes since commit 9643609423c7667fb748cc3ccff023d761d0ac90:

  Revert "ipv4: tunnel: fix compilation on ARCH=um" (2020-08-12 13:26:37 -0700)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can.git tags/linux-can-fixes-for-5.9-20200814

for you to fetch changes up to e052d0540298bfe0f6cbbecdc7e2ea9b859575b2:

  can: j1939: transport: j1939_xtp_rx_dat_one(): compare own packets to detect corruptions (2020-08-14 12:38:47 +0200)

----------------------------------------------------------------
linux-can-fixes-for-5.9-20200814

----------------------------------------------------------------
Eric Dumazet (1):
      can: j1939: fix kernel-infoleak in j1939_sk_sock2sockaddr_can()

Oleksij Rempel (5):
      can: j1939: transport: j1939_simple_recv(): ignore local J1939 messages send not by J1939 stack
      can: j1939: transport: j1939_session_tx_dat(): fix use-after-free read in j1939_tp_txtimer()
      can: j1939: socket: j1939_sk_bind(): make sure ml_priv is allocated
      can: j1939: transport: add j1939_session_skb_find_by_offset() function
      can: j1939: transport: j1939_xtp_rx_dat_one(): compare own packets to detect corruptions

 net/can/j1939/socket.c    | 14 ++++++++++++
 net/can/j1939/transport.c | 56 ++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 62 insertions(+), 8 deletions(-)

[PATCH 1/6] can: j1939: fix kernel-infoleak in j1939_sk_sock2sockaddr_can()

[Marc Kleine-Budde]

From: Eric Dumazet <edumazet@google.com>

syzbot found that at least 2 bytes of kernel information
were leaked during getsockname() on AF_CAN CAN_J1939 socket.

Since struct sockaddr_can has in fact two holes, simply
clear the whole area before filling it with useful data.

BUG: KMSAN: kernel-infoleak in kmsan_copy_to_user+0x81/0x90 mm/kmsan/kmsan_hooks.c:253
CPU: 0 PID: 8466 Comm: syz-executor511 Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x21c/0x280 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
 kmsan_internal_check_memory+0x238/0x3d0 mm/kmsan/kmsan.c:423
 kmsan_copy_to_user+0x81/0x90 mm/kmsan/kmsan_hooks.c:253
 instrument_copy_to_user include/linux/instrumented.h:91 [inline]
 _copy_to_user+0x18e/0x260 lib/usercopy.c:39
 copy_to_user include/linux/uaccess.h:186 [inline]
 move_addr_to_user+0x3de/0x670 net/socket.c:237
 __sys_getsockname+0x407/0x5e0 net/socket.c:1909
 __do_sys_getsockname net/socket.c:1920 [inline]
 __se_sys_getsockname+0x91/0xb0 net/socket.c:1917
 __x64_sys_getsockname+0x4a/0x70 net/socket.c:1917
 do_syscall_64+0xad/0x160 arch/x86/entry/common.c:386
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x440219
Code: Bad RIP value.
RSP: 002b:00007ffe5ee150c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000033
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440219
RDX: 0000000020000240 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401a20
R13: 0000000000401ab0 R14: 0000000000000000 R15: 0000000000000000

Local variable ----address@__sys_getsockname created at:
 __sys_getsockname+0x91/0x5e0 net/socket.c:1894
 __sys_getsockname+0x91/0x5e0 net/socket.c:1894

Bytes 2-3 of 24 are uninitialized
Memory access of size 24 starts at ffff8880ba2c7de8
Data copied to user address 0000000020000100

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Robin van der Gracht <robin@protonic.nl>
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: linux-can@vger.kernel.org
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20200813161834.4021638-1-edumazet@google.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/j1939/socket.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index 78ff9b3f1d40..b634b680177f 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -553,6 +553,11 @@ static int j1939_sk_connect(struct socket *sock, struct sockaddr *uaddr,
 static void j1939_sk_sock2sockaddr_can(struct sockaddr_can *addr,
 				       const struct j1939_sock *jsk, int peer)
 {
+	/* There are two holes (2 bytes and 3 bytes) to clear to avoid
+	 * leaking kernel information to user space.
+	 */
+	memset(addr, 0, J1939_MIN_NAMELEN);
+
 	addr->can_family = AF_CAN;
 	addr->can_ifindex = jsk->ifindex;
 	addr->can_addr.j1939.pgn = jsk->addr.pgn;
-- 
2.28.0

Re: [PATCH 1/6] can: j1939: fix kernel-infoleak in j1939_sk_sock2sockaddr_can()

[Eric Dumazet]

On Fri, Aug 14, 2020 at 6:20 AM Alexander Potapenko <glider@google.com> wrote:
>
>
>
> On Fri, Aug 14, 2020, 13:04 Marc Kleine-Budde <mkl@pengutronix.de> wrote:
>>
>> From: Eric Dumazet <edumazet@google.com>

>>  net/can/j1939/socket.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
>> index 78ff9b3f1d40..b634b680177f 100644
>> --- a/net/can/j1939/socket.c
>> +++ b/net/can/j1939/socket.c
>> @@ -553,6 +553,11 @@ static int j1939_sk_connect(struct socket *sock, struct sockaddr *uaddr,
>>  static void j1939_sk_sock2sockaddr_can(struct sockaddr_can *addr,
>>                                        const struct j1939_sock *jsk, int peer)
>>  {
>> +       /* There are two holes (2 bytes and 3 bytes) to clear to avoid
>> +        * leaking kernel information to user space.
>> +        */
>
>
> Do we want to keep these "2 bytes and 3 bytes' in sync with the struct layout in the future? Maybe it's not worth it to mention the exact sizes?

struct is uapi, you will have a hard time trying to use these holes,
since old kernels were sending crap/garbage/passwords ;)

[PATCH 2/6] can: j1939: transport: j1939_simple_recv(): ignore local J1939 messages send not by J1939 stack

[Marc Kleine-Budde]

From: Oleksij Rempel <o.rempel@pengutronix.de>

In current J1939 stack implementation, we process all locally send
messages as own messages. Even if it was send by CAN_RAW socket.

To reproduce it use following commands:
testj1939 -P -r can0:0x80 &
cansend can0 18238040#0123

This step will trigger false positive not critical warning:
j1939_simple_recv: Received already invalidated message

With this patch we add additional check to make sure, related skb is own
echo message.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20200807105200.26441-2-o.rempel@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/j1939/socket.c    | 1 +
 net/can/j1939/transport.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index b634b680177f..ad973370de12 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -398,6 +398,7 @@ static int j1939_sk_init(struct sock *sk)
 	spin_lock_init(&jsk->sk_session_queue_lock);
 	INIT_LIST_HEAD(&jsk->sk_session_queue);
 	sk->sk_destruct = j1939_sk_sock_destruct;
+	sk->sk_protocol = CAN_J1939;
 
 	return 0;
 }
diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 9f99af5b0b11..b135c5e2a86e 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -2017,6 +2017,10 @@ void j1939_simple_recv(struct j1939_priv *priv, struct sk_buff *skb)
 	if (!skb->sk)
 		return;
 
+	if (skb->sk->sk_family != AF_CAN ||
+	    skb->sk->sk_protocol != CAN_J1939)
+		return;
+
 	j1939_session_list_lock(priv);
 	session = j1939_session_get_simple(priv, skb);
 	j1939_session_list_unlock(priv);
-- 
2.28.0

[PATCH 3/6] can: j1939: transport: j1939_session_tx_dat(): fix use-after-free read in j1939_tp_txtimer()

[Marc Kleine-Budde]

From: Oleksij Rempel <o.rempel@pengutronix.de>

The current stack implementation do not support ECTS requests of not
aligned TP sized blocks.

If ECTS will request a block with size and offset spanning two TP
blocks, this will cause memcpy() to read beyond the queued skb (which
does only contain one TP sized block).

Sometimes KASAN will detect this read if the memory region beyond the
skb was previously allocated and freed. In other situations it will stay
undetected. The ETP transfer in any case will be corrupted.

This patch adds a sanity check to avoid this kind of read and abort the
session with error J1939_XTP_ABORT_ECTS_TOO_BIG.

Reported-by: syzbot+5322482fe520b02aea30@syzkaller.appspotmail.com
Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Cc: linux-stable <stable@vger.kernel.org> # >= v5.4
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20200807105200.26441-3-o.rempel@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/j1939/transport.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index b135c5e2a86e..30957c9a8eb7 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -787,6 +787,18 @@ static int j1939_session_tx_dat(struct j1939_session *session)
 		if (len > 7)
 			len = 7;
 
+		if (offset + len > se_skb->len) {
+			netdev_err_once(priv->ndev,
+					"%s: 0x%p: requested data outside of queued buffer: offset %i, len %i, pkt.tx: %i\n",
+					__func__, session, skcb->offset, se_skb->len , session->pkt.tx);
+			return -EOVERFLOW;
+		}
+
+		if (!len) {
+			ret = -ENOBUFS;
+			break;
+		}
+
 		memcpy(&dat[1], &tpdat[offset], len);
 		ret = j1939_tp_tx_dat(session, dat, len + 1);
 		if (ret < 0) {
@@ -1120,6 +1132,9 @@ static enum hrtimer_restart j1939_tp_txtimer(struct hrtimer *hrtimer)
 		 * cleanup including propagation of the error to user space.
 		 */
 		break;
+	case -EOVERFLOW:
+		j1939_session_cancel(session, J1939_XTP_ABORT_ECTS_TOO_BIG);
+		break;
 	case 0:
 		session->tx_retry = 0;
 		break;
-- 
2.28.0

[PATCH 4/6] can: j1939: socket: j1939_sk_bind(): make sure ml_priv is allocated

[Marc Kleine-Budde]

From: Oleksij Rempel <o.rempel@pengutronix.de>

This patch adds check to ensure that the struct net_device::ml_priv is
allocated, as it is used later by the j1939 stack.

The allocation is done by all mainline CAN network drivers, but when using
bond or team devices this is not the case.

Bail out if no ml_priv is allocated.

Reported-by: syzbot+f03d384f3455d28833eb@syzkaller.appspotmail.com
Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Cc: linux-stable <stable@vger.kernel.org> # >= v5.4
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20200807105200.26441-4-o.rempel@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/j1939/socket.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index ad973370de12..b93876c57fc4 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -467,6 +467,14 @@ static int j1939_sk_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 			goto out_release_sock;
 		}
 
+		if (!ndev->ml_priv) {
+			netdev_warn_once(ndev,
+					 "No CAN mid layer private allocated, please fix your driver and use alloc_candev()!\n");
+			dev_put(ndev);
+			ret = -ENODEV;
+			goto out_release_sock;
+		}
+
 		priv = j1939_netdev_start(ndev);
 		dev_put(ndev);
 		if (IS_ERR(priv)) {
-- 
2.28.0

[PATCH 5/6] can: j1939: transport: add j1939_session_skb_find_by_offset() function

[Marc Kleine-Budde]

From: Oleksij Rempel <o.rempel@pengutronix.de>

Sometimes it makes no sense to search the skb by pkt.dpo, since we need
next the skb within the transaction block. This may happen if we have an
ETP session with CTS set to less than 255 packets.

After this patch, we will be able to work with ETP sessions where the
block size (ETP.CM_CTS byte 2) is less than 255 packets.

Reported-by: Henrique Figueira <henrislip@gmail.com>
Reported-by: https://github.com/linux-can/can-utils/issues/228
Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20200807105200.26441-5-o.rempel@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/j1939/transport.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 30957c9a8eb7..90a2baac8a4a 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -352,17 +352,16 @@ void j1939_session_skb_queue(struct j1939_session *session,
 	skb_queue_tail(&session->skb_queue, skb);
 }
 
-static struct sk_buff *j1939_session_skb_find(struct j1939_session *session)
+static struct
+sk_buff *j1939_session_skb_find_by_offset(struct j1939_session *session,
+					  unsigned int offset_start)
 {
 	struct j1939_priv *priv = session->priv;
+	struct j1939_sk_buff_cb *do_skcb;
 	struct sk_buff *skb = NULL;
 	struct sk_buff *do_skb;
-	struct j1939_sk_buff_cb *do_skcb;
-	unsigned int offset_start;
 	unsigned long flags;
 
-	offset_start = session->pkt.dpo * 7;
-
 	spin_lock_irqsave(&session->skb_queue.lock, flags);
 	skb_queue_walk(&session->skb_queue, do_skb) {
 		do_skcb = j1939_skb_to_cb(do_skb);
@@ -382,6 +381,14 @@ static struct sk_buff *j1939_session_skb_find(struct j1939_session *session)
 	return skb;
 }
 
+static struct sk_buff *j1939_session_skb_find(struct j1939_session *session)
+{
+	unsigned int offset_start;
+
+	offset_start = session->pkt.dpo * 7;
+	return j1939_session_skb_find_by_offset(session, offset_start);
+}
+
 /* see if we are receiver
  * returns 0 for broadcasts, although we will receive them
  */
@@ -766,7 +773,7 @@ static int j1939_session_tx_dat(struct j1939_session *session)
 	int ret = 0;
 	u8 dat[8];
 
-	se_skb = j1939_session_skb_find(session);
+	se_skb = j1939_session_skb_find_by_offset(session, session->pkt.tx * 7);
 	if (!se_skb)
 		return -ENOBUFS;
 
@@ -1765,7 +1772,8 @@ static void j1939_xtp_rx_dat_one(struct j1939_session *session,
 			    __func__, session);
 		goto out_session_cancel;
 	}
-	se_skb = j1939_session_skb_find(session);
+
+	se_skb = j1939_session_skb_find_by_offset(session, packet * 7);
 	if (!se_skb) {
 		netdev_warn(priv->ndev, "%s: 0x%p: no skb found\n", __func__,
 			    session);
-- 
2.28.0

[PATCH 6/6] can: j1939: transport: j1939_xtp_rx_dat_one(): compare own packets to detect corruptions

[Marc Kleine-Budde]

From: Oleksij Rempel <o.rempel@pengutronix.de>

Since the stack relays on receiving own packets, it was overwriting own
transmit buffer from received packets.

At least theoretically, the received echo buffer can be corrupt or
changed and the session partner can request to resend previous data. In
this case we will re-send bad data.

With this patch we will stop to overwrite own TX buffer and use it for
sanity checking.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20200807105200.26441-6-o.rempel@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/j1939/transport.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 90a2baac8a4a..5cf107cb447c 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -1792,7 +1792,20 @@ static void j1939_xtp_rx_dat_one(struct j1939_session *session,
 	}
 
 	tpdat = se_skb->data;
-	memcpy(&tpdat[offset], &dat[1], nbytes);
+	if (!session->transmission) {
+		memcpy(&tpdat[offset], &dat[1], nbytes);
+	} else {
+		int err;
+
+		err = memcmp(&tpdat[offset], &dat[1], nbytes);
+		if (err)
+			netdev_err_once(priv->ndev,
+					"%s: 0x%p: Data of RX-looped back packet (%*ph) doesn't match TX data (%*ph)!\n",
+					__func__, session,
+					nbytes, &dat[1],
+					nbytes, &tpdat[offset]);
+	}
+
 	if (packet == session->pkt.rx)
 		session->pkt.rx++;
 
-- 
2.28.0

Re: pull-request: can 2020-08-14

[David Miller]

From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: Fri, 14 Aug 2020 13:04:22 +0200

> this is a pull request of 6 patches for net/master. All patches fix problems in
> the j1939 CAN networking stack.
> 
> The first patch is by Eric Dumazet fixes a kernel-infoleak in
> j1939_sk_sock2sockaddr_can().
> 
> The remaining 5 patches are by Oleksij Rempel and fix recption of j1939
> messages not orginated by the stack, a use-after-free in j1939_tp_txtimer(),
> ensure that the CAN driver has a ml_priv allocated. These problem were found by
> google's syzbot. Further ETP sessions with block size of less than 255 are
> fixed and a sanity check was added to j1939_xtp_rx_dat_one() to detect packet
> corruption.

Pulled, thank you Marc.