[PATCH 10/24] Bluetooth: Verify dlci not in use before rfcomm_dev create

Peter Hurley
2014-02-10T02:27:47Z

Only one session/channel combination may be in use at any one
time. However, the failure does not occur until the tty is
opened (in rfcomm_dlc_open()).

Because these settings are actually bound at rfcomm device
creation (via RFCOMMCREATEDEV ioctl), validate and fail before
creating the rfcomm tty device.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
include/net/bluetooth/rfcomm.h | 1 +
net/bluetooth/rfcomm/core.c | 26 +++++++++++++++++++++++++-
net/bluetooth/rfcomm/tty.c | 8 ++++++++
3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/include/net/bluetooth/rfcomm.h b/include/net/bluetooth/rfcomm.h
index 6f3fbc5..79bb913 100644
--- a/include/net/bluetooth/rfcomm.h
+++ b/include/net/bluetooth/rfcomm.h
@@ -241,6 +241,7 @@ int rfcomm_dlc_send(struct rfcomm_dlc *d, struct sk_buff *skb);
int rfcomm_dlc_set_modem_status(struct rfcomm_dlc *d, u8 v24_sig);
int rfcomm_dlc_get_modem_status(struct rfcomm_dlc *d, u8 *v24_sig);
void rfcomm_dlc_accept(struct rfcomm_dlc *d);
+struct rfcomm_dlc *rfcomm_dlc_exists(bdaddr_t *src, bdaddr_t *dst, u8 channel);

#define rfcomm_dlc_lock(d) spin_lock(&d->lock)
#define rfcomm_dlc_unlock(d) spin_unlock(&d->lock)
diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index facd8a7..646b6ff 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -359,6 +359,11 @@ static struct rfcomm_dlc *rfcomm_dlc_get(struct rfcomm_session *s, u8 dlci)
return NULL;
}

+static int rfcomm_check_channel(u8 channel)
+{
+ return channel < 1 || channel > 30;
+}
+
static int __rfcomm_dlc_open(struct rfcomm_dlc *d, bdaddr_t *src, bdaddr_t *dst, u8 channel)
{
struct rfcomm_session *s;
@@ -368,7 +373,7 @@ static int __rfcomm_dlc_open(struct rfcomm_dlc *d, bdaddr_t *src, bdaddr_t *dst,
BT_DBG("dlc %p state %ld %pMR -> %pMR channel %d",
d, d->state, src, dst, channel);

- if (channel < 1 || channel > 30)
+ if (rfcomm_check_channel(channel))
return -EINVAL;

if (d->state != BT_OPEN && d->state != BT_CLOSED)
@@ -513,6 +518,25 @@ no_session:
return r;
}

+struct rfcomm_dlc *rfcomm_dlc_exists(bdaddr_t *src, bdaddr_t *dst, u8 channel)
+{
+ struct rfcomm_session *s;
+ struct rfcomm_dlc *dlc = NULL;
+ u8 dlci;
+
+ if (rfcomm_check_channel(channel))
+ return ERR_PTR(-EINVAL);
+
+ rfcomm_lock();
+ s = rfcomm_session_get(src, dst);
+ if (s) {
+ dlci = __dlci(!s->initiator, channel);
+ dlc = rfcomm_dlc_get(s, dlci);
+ }
+ rfcomm_unlock();
+ return dlc;
+}
+
int rfcomm_dlc_send(struct rfcomm_dlc *d, struct sk_buff *skb)
{
int len = skb->len;
diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 6ea08b0..a58d693 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -385,6 +385,14 @@ static int rfcomm_create_dev(struct sock *sk, void __user *arg)
dlc = rfcomm_pi(sk)->dlc;
rfcomm_dlc_hold(dlc);
} else {
+ /* Validate the channel is unused */
+ dlc = rfcomm_dlc_exists(&req.src, &req.dst, req.channel);
+ if (IS_ERR(dlc))
+ return PTR_ERR(dlc);
+ else if (dlc) {
+ rfcomm_dlc_put(dlc);
+ return -EBUSY;
+ }
dlc = rfcomm_dlc_alloc(GFP_KERNEL);
if (!dlc)
return -ENOMEM;
--
1.8.1.2