Re: [PATCH] Bluetooth: Allow SCO/eSCO packet type selection for outgoing SCO connections.

[Nick Pelly <npelly@google.com>]

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On Wed, Feb 17, 2010 at 9:31 AM, Marcel Holtmann <marcel@holtmann.org> wrote:
> Hi Nick,
>
>> >> As a first step, can we get consensus on the userspace API:
>> >>
>> >> --- a/include/net/bluetooth/hci.h
>> >> +++ b/include/net/bluetooth/hci.h
>> >> @@ -139,8 +139,11 @@ enum {
>> >> +#define ALL_SCO_PKTS   (SCO_ESCO_MASK | EDR_ESCO_MASK)
>> >> +#define ALL_ESCO_PKTS  (SCO_ESCO_MASK | ESCO_EV3 | ESCO_EV4 | ESCO_EV5)
>> >>
>> >> --- a/include/net/bluetooth/sco.h
>> >> +++ b/include/net/bluetooth/sco.h
>> >> @@ -37,6 +37,7 @@
>> >> struct sockaddr_sco {
>> >>       sa_family_t     sco_family;
>> >>       bdaddr_t        sco_bdaddr;
>> >> +       __u16           sco_pkt_type;
>> >> };
>> >>
>> >> This will at least unblock my work.
>> >
>> > Would it be better to add new sockopt for sco socket?
>>
>> What advantage does that have?
>>
>> Putting it in struct sockaddr_sco seems to make more sense since
>> packet types can only be selected during SCO connection establishment.
>> They can't be changed once the socket is connected.
>
> in theory you can change the allowed packet types for ACL, SCO and eSCO
> after the connection is active. However the usefulness here is fairly
> limited. In case of ACL it is purely academical and most link manager
> will just ignore you. Mainly because the host stack can't really make a
> good decision here anyway.
>
> Personally I think it is a total brain dead concept to give this into
> the control of the host stack anyway. For eSCO packet types this make a
> bit more sense since you might wanna control the bandwidth. However
> changing them later is just pointless. And I don't recall of any profile
> actually mentioning about it. I think they had a great idea behind eSCO
> support, but since it is impossible to get the negotiation parts right,
> everybody sticks with simple eSCO channels and doesn't bother to change
> them.
>
> And even if we would be going for a setsockopt(), that would be blocking
> and then again pretty much pointless API. The sockaddr is most logical
> thing that fits into what we wanna achieve. Disallow/allow certain
> packet types and essentially force SCO over eSCO.

Ok seems like there is agreement on using struct sockaddr_sco for sco_pkt_type.

A more controversial question is whether to follow the SIG convention
of reversing the logic on the EDR bits in the packet type mask (1
means do *not* use this packet for the EDR bits), or to use consistent
logic for each bit (1 always means *allow* this packet type) for
packet selection in scokaddr_sco.sco_pkt_type.

The original patch I posted followed the SIG convention. However after
more thinking I am leaning towards using consistent logic for each
bit. 1 will always mean 'allow this packet'. My rationale is that the
most common use for sco_pkt_type will be to request only SCO packet
types allowed. If however the SIG adds more reverse logic packet
types, and we follow the SIG convention, then old userspace code that
just requested the SCO packet types will now end up with the new
packet types as well. So I think it is best to avoid this situation
and for 1 to always mean 'allow this packet' in
sockaddr_sco.sco_pkt_type.

Attached is a new patch with the consistent bit logic.

Comments?

Cheers,
Nick

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From 6efa97b316cf3f8897a64a739ea221879dc134dd Mon Sep 17 00:00:00 2001
From: Nick Pelly <npelly@google.com>
Date: Thu, 11 Feb 2010 11:54:28 -0800
Subject: [PATCH] Bluetooth: Allow SCO/eSCO packet type selection for outgoing SCO connections.

__u16 sco_pkt_type is introduced to struct sockaddr_sco. It allows bitwise
selection of SCO/eSCO packet types. Currently those bits are:

0x0001 HV1 may be used.
0x0002 HV2 may be used.
0x0004 HV3 may be used.
0x0008 EV3 may be used.
0x0010 EV4 may be used.
0x0020 EV5 may be used.
0x0040 2-EV3 may be used.
0x0080 3-EV3 may be used.
0x0100 2-EV5 may be used.
0x0200 3-EV5 may be used.

This is similar to the Packet Type parameter in the HCI Setup Synchronous
Connection Command, except that we are not reversing the logic on the EDR bits.
This makes the use of sco_pkt_tpye forward portable for the use case of
white-listing packet types, which we expect will be the primary use case.

If sco_pkt_type is zero, or userspace uses the old struct sockaddr_sco,
then the default behavior is to allow all packet types.

Packet type selection is just a request made to the Bluetooth chipset, and
it is up to the link manager on the chipset to negiotiate and decide on the
actual packet types used. Furthermore, when a SCO/eSCO connection is eventually
made there is no way for the host stack to determine which packet type was used
(however it is possible to get the link type of SCO or eSCO).

sco_pkt_type is ignored for incoming SCO connections. It is possible
to add this in the future as a parameter to the Accept Synchronous Connection
Command, however its a little trickier because the kernel does not
currently preserve sockaddr_sco data between userspace calls to accept().

The most common use for sco_pkt_type will be to white-list only SCO packets,
which can be done with the hci.h constant SCO_ESCO_MASK.

This patch is motivated by broken Bluetooth carkits such as the Motorolo
HF850 (it claims to support eSCO, but will actually reject eSCO connections
after 5 seconds) and the 2007/2008 Infiniti G35/37 (fails to route audio
if a 2-EV5 packet type is negiotiated). With this patch userspace can maintain
a list of compatible packet types to workaround remote devices such as these.

Based on a patch by Marcel Holtmann.

Signed-off-by: Nick Pelly <npelly@google.com>
---
 include/net/bluetooth/hci.h      |    6 ++-
 include/net/bluetooth/hci_core.h |    7 +++-
 include/net/bluetooth/sco.h      |    4 ++-
 net/bluetooth/hci_conn.c         |   33 ++++++++++++++-------
 net/bluetooth/hci_event.c        |    6 ++-
 net/bluetooth/l2cap.c            |    2 +-
 net/bluetooth/sco.c              |   60 +++++++++++++++++++++++++------------
 7 files changed, 79 insertions(+), 39 deletions(-)

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index 4f7795f..b32dcff 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -139,8 +139,10 @@ enum {
 #define ESCO_2EV5	0x0100
 #define ESCO_3EV5	0x0200
 
-#define SCO_ESCO_MASK  (ESCO_HV1 | ESCO_HV2 | ESCO_HV3)
-#define EDR_ESCO_MASK  (ESCO_2EV3 | ESCO_3EV3 | ESCO_2EV5 | ESCO_3EV5)
+#define SCO_ESCO_MASK	(ESCO_HV1 | ESCO_HV2 | ESCO_HV3)
+#define EDR_ESCO_MASK	(ESCO_2EV3 | ESCO_3EV3 | ESCO_2EV5 | ESCO_3EV5)
+#define ALL_ESCO_MASK	(SCO_ESCO_MASK | ESCO_EV3 | ESCO_EV4 | ESCO_EV5 | \
+			EDR_ESCO_MASK)
 
 /* ACL flags */
 #define ACL_START		0x00
diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index b6d36cb..cbcc5b1 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -326,12 +326,15 @@ void hci_acl_disconn(struct hci_conn *conn, __u8 reason);
 void hci_add_sco(struct hci_conn *conn, __u16 handle);
 void hci_setup_sync(struct hci_conn *conn, __u16 handle);
 
-struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst);
+struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type,
+					__u16 pkt_type, bdaddr_t *dst);
 int hci_conn_del(struct hci_conn *conn);
 void hci_conn_hash_flush(struct hci_dev *hdev);
 void hci_conn_check_pending(struct hci_dev *hdev);
 
-struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *dst, __u8 sec_level, __u8 auth_type);
+struct hci_conn *hci_connect(struct hci_dev *hdev, int type,
+					__u16 pkt_type, bdaddr_t *dst,
+					__u8 sec_level, __u8 auth_type);
 int hci_conn_check_link_mode(struct hci_conn *conn);
 int hci_conn_security(struct hci_conn *conn, __u8 sec_level, __u8 auth_type);
 int hci_conn_change_link_key(struct hci_conn *conn);
diff --git a/include/net/bluetooth/sco.h b/include/net/bluetooth/sco.h
index e28a2a7..924338a 100644
--- a/include/net/bluetooth/sco.h
+++ b/include/net/bluetooth/sco.h
@@ -37,6 +37,7 @@
 struct sockaddr_sco {
 	sa_family_t	sco_family;
 	bdaddr_t	sco_bdaddr;
+	__u16		sco_pkt_type;
 };
 
 /* SCO socket options */
@@ -72,7 +73,8 @@ struct sco_conn {
 
 struct sco_pinfo {
 	struct bt_sock	bt;
-	__u32		flags;
+	__u16		pkt_type;
+
 	struct sco_conn	*conn;
 };
 
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index fa8b412..2f4d30f 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -196,7 +196,8 @@ static void hci_conn_idle(unsigned long arg)
 	hci_conn_enter_sniff_mode(conn);
 }
 
-struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst)
+struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type,
+					__u16 pkt_type, bdaddr_t *dst)
 {
 	struct hci_conn *conn;
 
@@ -221,14 +222,22 @@ struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst)
 		conn->pkt_type = hdev->pkt_type & ACL_PTYPE_MASK;
 		break;
 	case SCO_LINK:
-		if (lmp_esco_capable(hdev))
-			conn->pkt_type = (hdev->esco_type & SCO_ESCO_MASK) |
-					(hdev->esco_type & EDR_ESCO_MASK);
-		else
-			conn->pkt_type = hdev->pkt_type & SCO_PTYPE_MASK;
-		break;
+		if (!pkt_type)
+			pkt_type = SCO_ESCO_MASK;
 	case ESCO_LINK:
-		conn->pkt_type = hdev->esco_type & ~EDR_ESCO_MASK;
+		if (!pkt_type)
+			pkt_type = ALL_ESCO_MASK;
+		if (lmp_esco_capable(hdev)) {
+			/* HCI Setup Synchronous Connection Command uses
+			   reverse logic on the EDR_ESCO_MASK bits */
+			conn->pkt_type = (pkt_type ^ EDR_ESCO_MASK) &
+					hdev->esco_type;
+		} else {
+			/* Legacy HCI Add Sco Connection Command uses a
+			   shifted bitmask */
+			conn->pkt_type = (pkt_type << 5) & hdev->pkt_type &
+					SCO_PTYPE_MASK;
+		}
 		break;
 	}
 
@@ -340,7 +349,9 @@ EXPORT_SYMBOL(hci_get_route);
 
 /* Create SCO or ACL connection.
  * Device _must_ be locked */
-struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *dst, __u8 sec_level, __u8 auth_type)
+struct hci_conn *hci_connect(struct hci_dev *hdev, int type,
+					__u16 pkt_type, bdaddr_t *dst,
+					__u8 sec_level, __u8 auth_type)
 {
 	struct hci_conn *acl;
 	struct hci_conn *sco;
@@ -348,7 +359,7 @@ struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *dst, __u8
 	BT_DBG("%s dst %s", hdev->name, batostr(dst));
 
 	if (!(acl = hci_conn_hash_lookup_ba(hdev, ACL_LINK, dst))) {
-		if (!(acl = hci_conn_add(hdev, ACL_LINK, dst)))
+		if (!(acl = hci_conn_add(hdev, ACL_LINK, 0, dst)))
 			return NULL;
 	}
 
@@ -364,7 +375,7 @@ struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *dst, __u8
 		return acl;
 
 	if (!(sco = hci_conn_hash_lookup_ba(hdev, type, dst))) {
-		if (!(sco = hci_conn_add(hdev, type, dst))) {
+		if (!(sco = hci_conn_add(hdev, type, pkt_type, dst))) {
 			hci_conn_put(acl);
 			return NULL;
 		}
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 10edd1a..5343e0f 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -579,7 +579,7 @@ static inline void hci_cs_create_conn(struct hci_dev *hdev, __u8 status)
 		}
 	} else {
 		if (!conn) {
-			conn = hci_conn_add(hdev, ACL_LINK, &cp->bdaddr);
+			conn = hci_conn_add(hdev, ACL_LINK, 0, &cp->bdaddr);
 			if (conn) {
 				conn->out = 1;
 				conn->link_mode |= HCI_LM_MASTER;
@@ -964,7 +964,9 @@ static inline void hci_conn_request_evt(struct hci_dev *hdev, struct sk_buff *sk
 
 		conn = hci_conn_hash_lookup_ba(hdev, ev->link_type, &ev->bdaddr);
 		if (!conn) {
-			if (!(conn = hci_conn_add(hdev, ev->link_type, &ev->bdaddr))) {
+			/* pkt_type not yet used for incoming connections */
+			if (!(conn = hci_conn_add(hdev, ev->link_type, 0,
+							&ev->bdaddr))) {
 				BT_ERR("No memmory for new connection");
 				hci_dev_unlock(hdev);
 				return;
diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index d056886..b342f06 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -955,7 +955,7 @@ static int l2cap_do_connect(struct sock *sk)
 		}
 	}
 
-	hcon = hci_connect(hdev, ACL_LINK, dst,
+	hcon = hci_connect(hdev, ACL_LINK, 0, dst,
 					l2cap_pi(sk)->sec_level, auth_type);
 	if (!hcon)
 		goto done;
diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index 77f4153..754db7a 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -176,6 +176,7 @@ static int sco_connect(struct sock *sk)
 {
 	bdaddr_t *src = &bt_sk(sk)->src;
 	bdaddr_t *dst = &bt_sk(sk)->dst;
+	__u16 pkt_type = sco_pi(sk)->pkt_type;
 	struct sco_conn *conn;
 	struct hci_conn *hcon;
 	struct hci_dev  *hdev;
@@ -192,10 +193,13 @@ static int sco_connect(struct sock *sk)
 
 	if (lmp_esco_capable(hdev) && !disable_esco)
 		type = ESCO_LINK;
-	else
+	else {
 		type = SCO_LINK;
+		pkt_type &= SCO_ESCO_MASK;
+	}
 
-	hcon = hci_connect(hdev, type, dst, BT_SECURITY_LOW, HCI_AT_NO_BONDING);
+	hcon = hci_connect(hdev, type, pkt_type, dst,
+					BT_SECURITY_LOW, HCI_AT_NO_BONDING);
 	if (!hcon)
 		goto done;
 
@@ -451,18 +455,22 @@ static int sco_sock_create(struct net *net, struct socket *sock, int protocol)
 	return 0;
 }
 
-static int sco_sock_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
+static int sco_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
 {
-	struct sockaddr_sco *sa = (struct sockaddr_sco *) addr;
+	struct sockaddr_sco sa;
 	struct sock *sk = sock->sk;
-	bdaddr_t *src = &sa->sco_bdaddr;
-	int err = 0;
+	bdaddr_t *src = &sa.sco_bdaddr;
+	int len, err = 0;
 
-	BT_DBG("sk %p %s", sk, batostr(&sa->sco_bdaddr));
+	BT_DBG("sk %p %s", sk, batostr(&sa.sco_bdaddr));
 
 	if (!addr || addr->sa_family != AF_BLUETOOTH)
 		return -EINVAL;
 
+	memset(&sa, 0, sizeof(sa));
+	len = min_t(unsigned int, sizeof(sa), alen);
+	memcpy(&sa, addr, len);
+
 	lock_sock(sk);
 
 	if (sk->sk_state != BT_OPEN) {
@@ -476,7 +484,8 @@ static int sco_sock_bind(struct socket *sock, struct sockaddr *addr, int addr_le
 		err = -EADDRINUSE;
 	} else {
 		/* Save source address */
-		bacpy(&bt_sk(sk)->src, &sa->sco_bdaddr);
+		bacpy(&bt_sk(sk)->src, &sa.sco_bdaddr);
+		sco_pi(sk)->pkt_type = sa.sco_pkt_type;
 		sk->sk_state = BT_BOUND;
 	}
 
@@ -489,26 +498,34 @@ done:
 
 static int sco_sock_connect(struct socket *sock, struct sockaddr *addr, int alen, int flags)
 {
-	struct sockaddr_sco *sa = (struct sockaddr_sco *) addr;
 	struct sock *sk = sock->sk;
-	int err = 0;
-
+	struct sockaddr_sco sa;
+	int len, err = 0;
 
 	BT_DBG("sk %p", sk);
 
-	if (addr->sa_family != AF_BLUETOOTH || alen < sizeof(struct sockaddr_sco))
+	if (!addr || addr->sa_family != AF_BLUETOOTH)
 		return -EINVAL;
 
-	if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND)
-		return -EBADFD;
-
-	if (sk->sk_type != SOCK_SEQPACKET)
-		return -EINVAL;
+	memset(&sa, 0, sizeof(sa));
+	len = min_t(unsigned int, sizeof(sa), alen);
+	memcpy(&sa, addr, len);
 
 	lock_sock(sk);
 
+	if (sk->sk_type != SOCK_SEQPACKET) {
+		err = -EINVAL;
+		goto done;
+	}
+
+	if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) {
+		err = -EBADFD;
+		goto done;
+	}
+
 	/* Set destination address and psm */
-	bacpy(&bt_sk(sk)->dst, &sa->sco_bdaddr);
+	bacpy(&bt_sk(sk)->dst, &sa.sco_bdaddr);
+	sco_pi(sk)->pkt_type = sa.sco_pkt_type;
 
 	if ((err = sco_connect(sk)))
 		goto done;
@@ -610,10 +627,13 @@ static int sco_sock_getname(struct socket *sock, struct sockaddr *addr, int *len
 	addr->sa_family = AF_BLUETOOTH;
 	*len = sizeof(struct sockaddr_sco);
 
-	if (peer)
+	if (peer) {
 		bacpy(&sa->sco_bdaddr, &bt_sk(sk)->dst);
-	else
+		sa->sco_pkt_type = sco_pi(sk)->pkt_type;
+	} else {
 		bacpy(&sa->sco_bdaddr, &bt_sk(sk)->src);
+		sa->sco_pkt_type = sco_pi(sk)->pkt_type;
+	}
 
 	return 0;
 }
-- 
1.6.5.3