Bluetooth: Allow setting of L2CAP ERTM via socket option

To enable Enhanced Retransmission mode it needs to be set via a socket
option. A different mode can be set on a socket, but on listen() and
connect() the mode is checked and ERTM is only allowed if it is enabled
via the module parameter.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 33 insertions, 4 deletions

diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index 810a3c1a4188..8a59e57d9df1 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -717,12 +717,16 @@ static void l2cap_sock_init(struct sock *sk, struct sock *parent)
 
                 pi->imtu = l2cap_pi(parent)->imtu;
                 pi->omtu = l2cap_pi(parent)->omtu;
+                pi->mode = l2cap_pi(parent)->mode;
+                pi->fcs  = l2cap_pi(parent)->fcs;
                 pi->sec_level = l2cap_pi(parent)->sec_level;
                 pi->role_switch = l2cap_pi(parent)->role_switch;
                 pi->force_reliable = l2cap_pi(parent)->force_reliable;
         } else {
                 pi->imtu = L2CAP_DEFAULT_MTU;
                 pi->omtu = 0;
+                pi->mode = L2CAP_MODE_BASIC;
+                pi->fcs  = L2CAP_FCS_CRC16;
                 pi->sec_level = BT_SECURITY_LOW;
                 pi->role_switch = 0;
                 pi->force_reliable = 0;
@@ -958,6 +962,18 @@ static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr, int al
                 goto done;
         }
 
+        switch (l2cap_pi(sk)->mode) {
+        case L2CAP_MODE_BASIC:
+                break;
+        case L2CAP_MODE_ERTM:
+                if (enable_ertm)
+                        break;
+                /* fall through */
+        default:
+                err = -ENOTSUPP;
+                goto done;
+        }
+
         switch (sk->sk_state) {
         case BT_CONNECT:
         case BT_CONNECT2:
@@ -1009,6 +1025,18 @@ static int l2cap_sock_listen(struct socket *sock, int backlog)
                 goto done;
         }
 
+        switch (l2cap_pi(sk)->mode) {
+        case L2CAP_MODE_BASIC:
+                break;
+        case L2CAP_MODE_ERTM:
+                if (enable_ertm)
+                        break;
+                /* fall through */
+        default:
+                err = -ENOTSUPP;
+                goto done;
+        }
+
         if (!l2cap_pi(sk)->psm) {
                 bdaddr_t *src = &bt_sk(sk)->src;
                 u16 psm;
@@ -1259,7 +1287,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
                 opts.imtu     = l2cap_pi(sk)->imtu;
                 opts.omtu     = l2cap_pi(sk)->omtu;
                 opts.flush_to = l2cap_pi(sk)->flush_to;
-                opts.mode     = L2CAP_MODE_BASIC;
+                opts.mode     = l2cap_pi(sk)->mode;
 
                 len = min_t(unsigned int, sizeof(opts), optlen);
                 if (copy_from_user((char *) &opts, optval, len)) {
@@ -1267,8 +1295,9 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
                         break;
                 }
 
-                l2cap_pi(sk)->imtu  = opts.imtu;
-                l2cap_pi(sk)->omtu  = opts.omtu;
+                l2cap_pi(sk)->imtu = opts.imtu;
+                l2cap_pi(sk)->omtu = opts.omtu;
+                l2cap_pi(sk)->mode = opts.mode;
                 break;
 
         case L2CAP_LM:
@@ -1381,7 +1410,7 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, char __us
                 opts.imtu     = l2cap_pi(sk)->imtu;
                 opts.omtu     = l2cap_pi(sk)->omtu;
                 opts.flush_to = l2cap_pi(sk)->flush_to;
-                opts.mode     = L2CAP_MODE_BASIC;
+                opts.mode     = l2cap_pi(sk)->mode;
 
                 len = min_t(unsigned int, len, sizeof(opts));
                 if (copy_to_user(optval, (char *) &opts, len))