[Bluetooth] Fix L2CAP configuration parameter handling

The L2CAP configuration parameter handling was missing the support
for rejecting unknown options. The capability to reject unknown
options is mandatory since the Bluetooth 1.2 specification. This
patch implements its and also simplifies the parameter parsing.

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

2 files changed, 86 insertions, 66 deletions

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 8242a0ee1f58..87df4e87622d 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -129,8 +129,10 @@ struct l2cap_conf_rsp {
         __u8       data[0];
 } __attribute__ ((packed));
 
-#define L2CAP_CONF_SUCCESS      0x00
-#define L2CAP_CONF_UNACCEPT     0x01
+#define L2CAP_CONF_SUCCESS      0x0000
+#define L2CAP_CONF_UNACCEPT     0x0001
+#define L2CAP_CONF_REJECT       0x0002
+#define L2CAP_CONF_UNKNOWN      0x0003
 
 struct l2cap_conf_opt {
         __u8       type;
@@ -215,6 +217,8 @@ struct l2cap_pinfo {
 
         __u32           link_mode;
 
+        __u8            conf_req[64];
+        __u8            conf_len;
         __u8            conf_state;
         __u8            conf_retry;
         __u16           conf_mtu;
diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index a59b1fb63b76..670ff95ca64b 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -507,6 +507,7 @@ static void l2cap_sock_init(struct sock *sk, struct sock *parent)
         }
 
         /* Default config options */
+        pi->conf_len = 0;
         pi->conf_mtu = L2CAP_DEFAULT_MTU;
         pi->flush_to = L2CAP_DEFAULT_FLUSH_TO;
 }
@@ -1271,42 +1272,6 @@ static inline int l2cap_get_conf_opt(void **ptr, int *type, int *olen, unsigned
         return len;
 }
 
-static inline void l2cap_parse_conf_req(struct sock *sk, void *data, int len)
-{
-        int type, hint, olen;
-        unsigned long val;
-        void *ptr = data;
-
-        BT_DBG("sk %p len %d", sk, len);
-
-        while (len >= L2CAP_CONF_OPT_SIZE) {
-                len -= l2cap_get_conf_opt(&ptr, &type, &olen, &val);
-
-                hint  = type & 0x80;
-                type &= 0x7f;
-
-                switch (type) {
-                case L2CAP_CONF_MTU:
-                        l2cap_pi(sk)->conf_mtu = val;
-                        break;
-
-                case L2CAP_CONF_FLUSH_TO:
-                        l2cap_pi(sk)->flush_to = val;
-                        break;
-
-                case L2CAP_CONF_QOS:
-                        break;
-
-                default:
-                        if (hint)
-                                break;
-
-                        /* FIXME: Reject unknown option */
-                        break;
-                }
-        }
-}
-
 static void l2cap_add_conf_opt(void **ptr, u8 type, u8 len, unsigned long val)
 {
         struct l2cap_conf_opt *opt = *ptr;
@@ -1358,39 +1323,75 @@ static int l2cap_build_conf_req(struct sock *sk, void *data)
         return ptr - data;
 }
 
-static inline int l2cap_conf_output(struct sock *sk, void **ptr)
+static int l2cap_parse_conf_req(struct sock *sk, void *data)
 {
         struct l2cap_pinfo *pi = l2cap_pi(sk);
-        int result = 0;
+        struct l2cap_conf_rsp *rsp = data;
+        void *ptr = rsp->data;
+        void *req = pi->conf_req;
+        int len = pi->conf_len;
+        int type, hint, olen;
+        unsigned long val;
+        u16 result = L2CAP_CONF_SUCCESS;
 
-        /* Configure output options and let the other side know
-         * which ones we don't like. */
-        if (pi->conf_mtu < pi->omtu)
-                result = L2CAP_CONF_UNACCEPT;
-        else
-                pi->omtu = pi->conf_mtu;
+        BT_DBG("sk %p", sk);
+
+        while (len >= L2CAP_CONF_OPT_SIZE) {
+                len -= l2cap_get_conf_opt(&req, &type, &olen, &val);
 
-        l2cap_add_conf_opt(ptr, L2CAP_CONF_MTU, 2, pi->omtu);
+                hint  = type & 0x80;
+                type &= 0x7f;
+
+                switch (type) {
+                case L2CAP_CONF_MTU:
+                        pi->conf_mtu = val;
+                        break;
+
+                case L2CAP_CONF_FLUSH_TO:
+                        pi->flush_to = val;
+                        break;
+
+                case L2CAP_CONF_QOS:
+                        break;
+
+                default:
+                        if (hint)
+                                break;
+
+                        result = L2CAP_CONF_UNKNOWN;
+                        *((u8 *) ptr++) = type;
+                        break;
+                }
+        }
+
+        if (result == L2CAP_CONF_SUCCESS) {
+                /* Configure output options and let the other side know
+                 * which ones we don't like. */
+
+                if (pi->conf_mtu < pi->omtu)
+                        result = L2CAP_CONF_UNACCEPT;
+                else
+                        pi->omtu = pi->conf_mtu;
+
+                l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, pi->omtu);
+        }
 
-        BT_DBG("sk %p result %d", sk, result);
-        return result;
+        rsp->scid   = cpu_to_le16(pi->dcid);
+        rsp->result = cpu_to_le16(result);
+        rsp->flags  = cpu_to_le16(0x0000);
+
+        return ptr - data;
 }
 
-static int l2cap_build_conf_rsp(struct sock *sk, void *data, int *result)
+static int l2cap_build_conf_rsp(struct sock *sk, void *data, u16 result, u16 flags)
 {
         struct l2cap_conf_rsp *rsp = data;
         void *ptr = rsp->data;
-        u16 flags = 0;
-
-        BT_DBG("sk %p complete %d", sk, result ? 1 : 0);
 
-        if (result)
-                *result = l2cap_conf_output(sk, &ptr);
-        else
-                flags = 0x0001;
+        BT_DBG("sk %p", sk);
 
         rsp->scid   = cpu_to_le16(l2cap_pi(sk)->dcid);
-        rsp->result = cpu_to_le16(result ? *result : 0);
+        rsp->result = cpu_to_le16(result);
         rsp->flags  = cpu_to_le16(flags);
 
         return ptr - data;
@@ -1535,7 +1536,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
         u16 dcid, flags;
         u8 rsp[64];
         struct sock *sk;
-        int result;
+        int len;
 
         dcid  = __le16_to_cpu(req->dcid);
         flags = __le16_to_cpu(req->flags);
@@ -1548,25 +1549,40 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
         if (sk->sk_state == BT_DISCONN)
                 goto unlock;
 
-        l2cap_parse_conf_req(sk, req->data, cmd->len - sizeof(*req));
+        /* Reject if config buffer is too small. */
+        len = cmd->len - sizeof(*req);
+        if (l2cap_pi(sk)->conf_len + len > sizeof(l2cap_pi(sk)->conf_req)) {
+                l2cap_send_cmd(conn, cmd->ident, L2CAP_CONF_RSP,
+                                l2cap_build_conf_rsp(sk, rsp,
+                                        L2CAP_CONF_REJECT, flags), rsp);
+                goto unlock;
+        }
+
+        /* Store config. */
+        memcpy(l2cap_pi(sk)->conf_req + l2cap_pi(sk)->conf_len, req->data, len);
+        l2cap_pi(sk)->conf_len += len;
 
         if (flags & 0x0001) {
                 /* Incomplete config. Send empty response. */
                 l2cap_send_cmd(conn, cmd->ident, L2CAP_CONF_RSP,
-                                l2cap_build_conf_rsp(sk, rsp, NULL), rsp);
+                                l2cap_build_conf_rsp(sk, rsp,
+                                        L2CAP_CONF_SUCCESS, 0x0001), rsp);
                 goto unlock;
         }
 
         /* Complete config. */
-        l2cap_send_cmd(conn, cmd->ident, L2CAP_CONF_RSP,
-                        l2cap_build_conf_rsp(sk, rsp, &result), rsp);
-
-        if (result)
+        len = l2cap_parse_conf_req(sk, rsp);
+        if (len < 0)
                 goto unlock;
 
-        /* Output config done */
+        l2cap_send_cmd(conn, cmd->ident, L2CAP_CONF_RSP, len, rsp);
+
+        /* Output config done. */
         l2cap_pi(sk)->conf_state |= L2CAP_CONF_OUTPUT_DONE;
 
+        /* Reset config buffer. */
+        l2cap_pi(sk)->conf_len = 0;
+
         if (l2cap_pi(sk)->conf_state & L2CAP_CONF_INPUT_DONE) {
                 sk->sk_state = BT_CONNECTED;
                 l2cap_chan_ready(sk);