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authorMarcel Holtmann <marcel@holtmann.org>2006-07-14 11:42:12 +0200
committerDavid S. Miller <davem@sunset.davemloft.net>2006-07-24 12:44:25 -0700
commit98bcd08b5bfe78c1c9bda5768aa081e0fe4fcc4f (patch)
tree171c7984eeaade72d57a325ee26d55e4408bbdd1
parent2266d8886f64c66e0a4e61e3e1c19dbc27ed00d4 (diff)
[Bluetooth] Correct RFCOMM channel MTU for broken implementations
Some Bluetooth RFCOMM implementations try to negotiate a bigger channel MTU than we can support for a particular session. The maximum MTU for a RFCOMM session is limited through the L2CAP layer. So if the other side proposes a channel MTU that is bigger than the underlying L2CAP MTU, we should reduce it to the L2CAP MTU of the session minus five bytes for the RFCOMM headers. Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
-rw-r--r--net/bluetooth/rfcomm/core.c19
1 files changed, 17 insertions, 2 deletions
diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index 77eab8f4c7f..332dd8f436e 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -55,6 +55,7 @@
#define VERSION "1.8"
static int disable_cfc = 0;
+static int channel_mtu = -1;
static unsigned int l2cap_mtu = RFCOMM_MAX_L2CAP_MTU;
static struct task_struct *rfcomm_thread;
@@ -812,7 +813,10 @@ static int rfcomm_send_pn(struct rfcomm_session *s, int cr, struct rfcomm_dlc *d
pn->credits = 0;
}
- pn->mtu = htobs(d->mtu);
+ if (cr && channel_mtu >= 0)
+ pn->mtu = htobs(channel_mtu);
+ else
+ pn->mtu = htobs(d->mtu);
*ptr = __fcs(buf); ptr++;
@@ -1243,7 +1247,10 @@ static int rfcomm_apply_pn(struct rfcomm_dlc *d, int cr, struct rfcomm_pn *pn)
d->priority = pn->priority;
- d->mtu = s->mtu = btohs(pn->mtu);
+ d->mtu = btohs(pn->mtu);
+
+ if (cr && d->mtu > s->mtu)
+ d->mtu = s->mtu;
return 0;
}
@@ -1770,6 +1777,11 @@ static inline void rfcomm_accept_connection(struct rfcomm_session *s)
s = rfcomm_session_add(nsock, BT_OPEN);
if (s) {
rfcomm_session_hold(s);
+
+ /* We should adjust MTU on incoming sessions.
+ * L2CAP MTU minus UIH header and FCS. */
+ s->mtu = min(l2cap_pi(nsock->sk)->omtu, l2cap_pi(nsock->sk)->imtu) - 5;
+
rfcomm_schedule(RFCOMM_SCHED_RX);
} else
sock_release(nsock);
@@ -2087,6 +2099,9 @@ module_exit(rfcomm_exit);
module_param(disable_cfc, bool, 0644);
MODULE_PARM_DESC(disable_cfc, "Disable credit based flow control");
+module_param(channel_mtu, int, 0644);
+MODULE_PARM_DESC(channel_mtu, "Default MTU for the RFCOMM channel");
+
module_param(l2cap_mtu, uint, 0644);
MODULE_PARM_DESC(l2cap_mtu, "Default MTU for the L2CAP connection");