On Wed, 27 Jul 2016, Marcel Holtmann wrote:
Hi Mat,
I modified the original patch to call sk_filter for ERTM before the packet is
handled by the state machine and to not set the filter locked flag. I tested
using l2test in ERTM mode, with and without a "randomly drop 1 in 64 packets"
filter attached.
Thanks for testing. For consistency's sake, is it preferable to filter
at this point for all modes?
Only ERTM and streaming mode end up on this code path, and I think there's a benefit to handling these two modes similarly. There are a number of other paths to l2cap_sock_recv_cb(), and there isn't one perfect place to call sk_filter for all modes.
would code restructuring help to create a better place to put sk_filter?
Maybe, but I'm not sure it's worthwhile for this purpose alone. The
handling for ERTM is similar to what I see for TCP, but for LE we want to
issue credits and do some more reassembly before filtering.
---
net/bluetooth/l2cap_core.c | 4 ++++
net/bluetooth/l2cap_sock.c | 13 +++++++++++--
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 54ceb1f..d5de0ce 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -32,6 +32,7 @@
#include <linux/debugfs.h>
#include <linux/crc16.h>
+#include <linux/filter.h>
#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>
@@ -6610,6 +6611,9 @@ static int l2cap_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
goto drop;
}
+ if (chan->mode == L2CAP_MODE_ERTM && sk_filter(chan->data, skb))
+ goto drop;
+
sk_filter can also accept, but trim, packets. If the protocol expects
a header that it unconditionally pulls later, use sk_filter_trim to
sk_filter_trim_cap? I see that you added that recently. It's not in bluetooth-next and we're aiming for a patch that can be easily backported to stable.
Lets create a version that fixes this first. One version that we can backport into stable. And then we can start utilizing newer infrastructure available in Linus' tree.
I believe v3 is a fix suitable for stable.
--
Mat Martineau
Intel OTC
--
To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
