Implement CRC16 check for L2CAP packets. FCS is used by Streaming Mode and
Enhanced Retransmission Mode and is a extra check for the packet content.
CRC16 is the default, L2CAP won't use FCS only when both side send a "No
FCS" request.
Initially based on a patch from Nathan Holstein <nathan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Gustavo F. Padovan <gustavo@xxxxxxxxxxxxxxxxx>
---
include/net/bluetooth/l2cap.h | 2 +
net/bluetooth/l2cap.c | 100 ++++++++++++++++++++++++++++++++++++++---
2 files changed, 96 insertions(+), 6 deletions(-)
diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 33aea42..abb1b56 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -54,6 +54,7 @@ struct l2cap_options {
__u16 imtu;
__u16 flush_to;
__u8 mode;
+ __u8 fcs;
};
#define L2CAP_CONNINFO 0x02
@@ -348,6 +349,7 @@ struct l2cap_pinfo {
#define L2CAP_CONF_MTU_DONE 0x08
#define L2CAP_CONF_MODE_DONE 0x10
#define L2CAP_CONF_CONNECT_PEND 0x20
+#define L2CAP_CONF_NO_FCS_RECV 0x40
#define L2CAP_CONF_STATE2_DEVICE 0x80
#define L2CAP_CONF_MAX_CONF_REQ 2
diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index 104d9fd..5ca0593 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -41,6 +41,7 @@
#include <linux/list.h>
#include <linux/device.h>
#include <linux/uaccess.h>
+#include <linux/crc16.h>
#include <net/sock.h>
#include <asm/system.h>
@@ -338,11 +339,14 @@ static inline int l2cap_send_sframe(struct l2cap_pinfo *pi, u16 control)
struct sk_buff *skb;
struct l2cap_hdr *lh;
struct l2cap_conn *conn = pi->conn;
- int count;
+ int count, hlen = L2CAP_HDR_SIZE + 2;
+
+ if (pi->fcs == L2CAP_FCS_CRC16)
+ hlen += 2;
BT_DBG("pi %p, control 0x%2.2x", pi, control);
- count = min_t(unsigned int, conn->mtu, L2CAP_HDR_SIZE + 2);
+ count = min_t(unsigned int, conn->mtu, hlen);
control |= L2CAP_CTRL_FRAME_TYPE;
skb = bt_skb_alloc(count, GFP_ATOMIC);
@@ -350,10 +354,15 @@ static inline int l2cap_send_sframe(struct l2cap_pinfo *pi, u16 control)
return -ENOMEM;
lh = (struct l2cap_hdr *) skb_put(skb, L2CAP_HDR_SIZE);
- lh->len = cpu_to_le16(2);
+ lh->len = cpu_to_le16(hlen - L2CAP_HDR_SIZE);
lh->cid = cpu_to_le16(pi->dcid);
put_unaligned_le16(control, skb_put(skb, 2));
+ if (pi->fcs == L2CAP_FCS_CRC16) {
+ u16 fcs = crc16(0, (u8 *)lh, count - 2);
+ put_unaligned_le16(fcs, skb_put(skb, 2));
+ }
+
return hci_send_acl(pi->conn->hcon, skb, 0);
}
@@ -1247,7 +1256,7 @@ static int l2cap_streaming_send(struct sock *sk)
{
struct sk_buff *skb, *tx_skb;
struct l2cap_pinfo *pi = l2cap_pi(sk);
- u16 control;
+ u16 control, fcs;
int err;
while ((skb = sk->sk_send_head)) {
@@ -1257,6 +1266,11 @@ static int l2cap_streaming_send(struct sock *sk)
control |= pi->next_tx_seq << L2CAP_CTRL_TXSEQ_SHIFT;
put_unaligned_le16(control, skb->data + L2CAP_HDR_SIZE);
+ if (l2cap_pi(sk)->fcs == L2CAP_FCS_CRC16) {
+ fcs = crc16(0, (u8 *)skb->data, skb->len - 2);
+ put_unaligned_le16(fcs, skb->data + skb->len - 2);
+ }
+
err = l2cap_do_send(sk, tx_skb);
if (err < 0) {
l2cap_send_disconn_req(pi->conn, sk);
@@ -1280,7 +1294,7 @@ static int l2cap_ertm_send(struct sock *sk)
{
struct sk_buff *skb, *tx_skb;
struct l2cap_pinfo *pi = l2cap_pi(sk);
- u16 control;
+ u16 control, fcs;
int err;
if (pi->conn_state & L2CAP_CONN_WAIT_ACK)
@@ -1303,6 +1317,11 @@ static int l2cap_ertm_send(struct sock *sk)
put_unaligned_le16(control, skb->data + L2CAP_HDR_SIZE);
+ if (l2cap_pi(sk)->fcs == L2CAP_FCS_CRC16) {
+ fcs = crc16(0, (u8 *)skb->data, skb->len - 2);
+ put_unaligned_le16(fcs, skb->data + skb->len - 2);
+ }
+
err = l2cap_do_send(sk, tx_skb);
if (err < 0) {
l2cap_send_disconn_req(pi->conn, sk);
@@ -1426,6 +1445,9 @@ static struct sk_buff *l2cap_create_iframe_pdu(struct sock *sk, struct msghdr *m
if (sdulen)
hlen += 2;
+ if (l2cap_pi(sk)->fcs == L2CAP_FCS_CRC16)
+ hlen += 2;
+
count = min_t(unsigned int, (conn->mtu - hlen), len);
skb = bt_skb_send_alloc(sk, count + hlen,
msg->msg_flags & MSG_DONTWAIT, &err);
@@ -1446,6 +1468,9 @@ static struct sk_buff *l2cap_create_iframe_pdu(struct sock *sk, struct msghdr *m
return ERR_PTR(err);
}
+ if (l2cap_pi(sk)->fcs == L2CAP_FCS_CRC16)
+ put_unaligned_le16(0, skb_put(skb, 2));
+
bt_cb(skb)->retries = 0;
return skb;
}
@@ -1631,6 +1656,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
opts.omtu = l2cap_pi(sk)->omtu;
opts.flush_to = l2cap_pi(sk)->flush_to;
opts.mode = l2cap_pi(sk)->mode;
+ opts.fcs = l2cap_pi(sk)->fcs;
len = min_t(unsigned int, sizeof(opts), optlen);
if (copy_from_user((char *) &opts, optval, len)) {
@@ -1641,6 +1667,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
l2cap_pi(sk)->imtu = opts.imtu;
l2cap_pi(sk)->omtu = opts.omtu;
l2cap_pi(sk)->mode = opts.mode;
+ l2cap_pi(sk)->fcs = opts.fcs;
break;
case L2CAP_LM:
@@ -1754,6 +1781,7 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, char __us
opts.omtu = l2cap_pi(sk)->omtu;
opts.flush_to = l2cap_pi(sk)->flush_to;
opts.mode = l2cap_pi(sk)->mode;
+ opts.fcs = l2cap_pi(sk)->fcs;
len = min_t(unsigned int, len, sizeof(opts));
if (copy_to_user(optval, (char *) &opts, len))
@@ -2152,6 +2180,15 @@ done:
l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC,
sizeof(rfc), (unsigned long) &rfc);
+
+ if (!(pi->conn->feat_mask & L2CAP_FEAT_FCS))
+ break;
+
+ if (pi->fcs == L2CAP_FCS_NONE ||
+ pi->conf_state & L2CAP_CONF_NO_FCS_RECV) {
+ pi->fcs = L2CAP_FCS_NONE;
+ l2cap_add_conf_opt(&ptr, L2CAP_CONF_FCS, 1, pi->fcs);
+ }
break;
case L2CAP_MODE_STREAMING:
@@ -2164,6 +2201,15 @@ done:
l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC,
sizeof(rfc), (unsigned long) &rfc);
+
+ if (!(pi->conn->feat_mask & L2CAP_FEAT_FCS))
+ break;
+
+ if (pi->fcs == L2CAP_FCS_NONE ||
+ pi->conf_state & L2CAP_CONF_NO_FCS_RECV) {
+ pi->fcs = L2CAP_FCS_NONE;
+ l2cap_add_conf_opt(&ptr, L2CAP_CONF_FCS, 1, pi->fcs);
+ }
break;
}
@@ -2215,6 +2261,12 @@ static int l2cap_parse_conf_req(struct sock *sk, void *data)
memcpy(&rfc, (void *) val, olen);
break;
+ case L2CAP_CONF_FCS:
+ if (val == L2CAP_FCS_NONE)
+ pi->conf_state |= L2CAP_CONF_NO_FCS_RECV;
+
+ break;
+
default:
if (hint)
break;
@@ -2636,6 +2688,10 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
goto unlock;
if (l2cap_pi(sk)->conf_state & L2CAP_CONF_INPUT_DONE) {
+ if (!(l2cap_pi(sk)->conf_state & L2CAP_CONF_NO_FCS_RECV)
+ || l2cap_pi(sk)->fcs != L2CAP_FCS_NONE)
+ l2cap_pi(sk)->fcs = L2CAP_FCS_CRC16;
+
sk->sk_state = BT_CONNECTED;
l2cap_pi(sk)->next_tx_seq = 0;
l2cap_pi(sk)->expected_ack_seq = 0;
@@ -2720,6 +2776,10 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hdr
l2cap_pi(sk)->conf_state |= L2CAP_CONF_INPUT_DONE;
if (l2cap_pi(sk)->conf_state & L2CAP_CONF_OUTPUT_DONE) {
+ if (!(l2cap_pi(sk)->conf_state & L2CAP_CONF_NO_FCS_RECV)
+ || l2cap_pi(sk)->fcs != L2CAP_FCS_NONE)
+ l2cap_pi(sk)->fcs = L2CAP_FCS_CRC16;
+
sk->sk_state = BT_CONNECTED;
l2cap_pi(sk)->expected_tx_seq = 0;
l2cap_pi(sk)->num_to_ack = 0;
@@ -2807,7 +2867,8 @@ static inline int l2cap_information_req(struct l2cap_conn *conn, struct l2cap_cm
rsp->type = cpu_to_le16(L2CAP_IT_FEAT_MASK);
rsp->result = cpu_to_le16(L2CAP_IR_SUCCESS);
if (enable_ertm)
- feat_mask |= L2CAP_FEAT_ERTM | L2CAP_FEAT_STREAMING;
+ feat_mask |= L2CAP_FEAT_ERTM | L2CAP_FEAT_STREAMING
+ | L2CAP_FEAT_FCS;
put_unaligned(cpu_to_le32(feat_mask), (__le32 *) rsp->data);
l2cap_send_cmd(conn, cmd->ident,
L2CAP_INFO_RSP, sizeof(buf), buf);
@@ -2958,6 +3019,21 @@ static inline void l2cap_sig_channel(struct l2cap_conn *conn, struct sk_buff *sk
kfree_skb(skb);
}
+static int l2cap_check_fcs(struct l2cap_pinfo *pi, struct sk_buff *skb)
+{
+ u16 our_fcs, rcv_fcs;
+ int hdr_size = L2CAP_HDR_SIZE + 2;
+
+ if (pi->fcs == L2CAP_FCS_CRC16) {
+ skb_trim(skb, skb->len - 2);
+ rcv_fcs = get_unaligned_le16(skb->data + skb->len);
+ our_fcs = crc16(0, skb->data - hdr_size, skb->len + hdr_size);
+
+ if (our_fcs != rcv_fcs)
+ return -EINVAL;
+ }
+ return 0;
+}
static int l2cap_sar_reassembly_sdu(struct sock *sk, struct sk_buff *skb, u16 control, u8 txseq)
{
@@ -3169,6 +3245,9 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
if (__is_sar_start(control))
len -= 2;
+ if (pi->fcs == L2CAP_FCS_CRC16)
+ len -= 2;
+
/*
* We can just drop the corrupted I-frame here.
* Receiver will miss it and start proper recovery
@@ -3177,6 +3256,9 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
if (len > L2CAP_DEFAULT_MAX_PDU_SIZE)
goto drop;
+ if (l2cap_check_fcs(pi, skb))
+ goto drop;
+
if (__is_iframe(control))
err = l2cap_data_channel_iframe(sk, control, skb);
else
@@ -3194,9 +3276,15 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
if (__is_sar_start(control))
len -= 2;
+ if (pi->fcs == L2CAP_FCS_CRC16)
+ len -= 2;
+
if (len > L2CAP_DEFAULT_MAX_PDU_SIZE || __is_sframe(control))
goto drop;
+ if (l2cap_check_fcs(pi, skb))
+ goto drop;
+
tx_seq = __get_txseq(control);
if (pi->expected_tx_seq == tx_seq)
--
1.6.3.3
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