[PATCH v2 3/5] Bluetooth: L2CAP: Fix not validating setsockopt user input

[Luiz Augusto von Dentz <luiz.dentz@xxxxxxxxx>]

From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>

Check user input length before copying data.

Fixes: 33575df7be67 ("Bluetooth: move l2cap_sock_setsockopt() to l2cap_sock.c")
Fixes: 3ee7b7cd8390 ("Bluetooth: Add BT_MODE socket option")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
---
 net/bluetooth/l2cap_sock.c | 52 +++++++++++++++-----------------------
 1 file changed, 20 insertions(+), 32 deletions(-)

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 7846a068bf60..b8913fbd77ce 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -728,7 +728,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname,
 	struct sock *sk = sock->sk;
 	struct l2cap_chan *chan = l2cap_pi(sk)->chan;
 	struct l2cap_options opts;
-	int len, err = 0;
+	int err = 0;
 	u32 opt;
 
 	BT_DBG("sk %p", sk);
@@ -755,11 +755,9 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname,
 		opts.max_tx   = chan->max_tx;
 		opts.txwin_size = chan->tx_win;
 
-		len = min_t(unsigned int, sizeof(opts), optlen);
-		if (copy_from_sockptr(&opts, optval, len)) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&opts, sizeof(opts), optval, optlen);
+		if (err)
 			break;
-		}
 
 		if (opts.txwin_size > L2CAP_DEFAULT_EXT_WINDOW) {
 			err = -EINVAL;
@@ -802,10 +800,9 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname,
 		break;
 
 	case L2CAP_LM:
-		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&opt, sizeof(opt), optval, optlen);
+		if (err)
 			break;
-		}
 
 		if (opt & L2CAP_LM_FIPS) {
 			err = -EINVAL;
@@ -886,7 +883,7 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 	struct bt_security sec;
 	struct bt_power pwr;
 	struct l2cap_conn *conn;
-	int len, err = 0;
+	int err = 0;
 	u32 opt;
 	u16 mtu;
 	u8 mode;
@@ -912,11 +909,9 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 
 		sec.level = BT_SECURITY_LOW;
 
-		len = min_t(unsigned int, sizeof(sec), optlen);
-		if (copy_from_sockptr(&sec, optval, len)) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&sec, sizeof(sec), optval, optlen);
+		if (err)
 			break;
-		}
 
 		if (sec.level < BT_SECURITY_LOW ||
 		    sec.level > BT_SECURITY_FIPS) {
@@ -961,10 +956,9 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 			break;
 		}
 
-		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&opt, sizeof(opt), optval, optlen);
+		if (err)
 			break;
-		}
 
 		if (opt) {
 			set_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags);
@@ -976,10 +970,9 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 		break;
 
 	case BT_FLUSHABLE:
-		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&opt, sizeof(opt), optval, optlen);
+		if (err)
 			break;
-		}
 
 		if (opt > BT_FLUSHABLE_ON) {
 			err = -EINVAL;
@@ -1011,11 +1004,9 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 
 		pwr.force_active = BT_POWER_FORCE_ACTIVE_ON;
 
-		len = min_t(unsigned int, sizeof(pwr), optlen);
-		if (copy_from_sockptr(&pwr, optval, len)) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&pwr, sizeof(pwr), optval, optlen);
+		if (err)
 			break;
-		}
 
 		if (pwr.force_active)
 			set_bit(FLAG_FORCE_ACTIVE, &chan->flags);
@@ -1024,10 +1015,9 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 		break;
 
 	case BT_CHANNEL_POLICY:
-		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&opt, sizeof(opt), optval, optlen);
+		if (err)
 			break;
-		}
 
 		err = -EOPNOTSUPP;
 		break;
@@ -1056,10 +1046,9 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 			break;
 		}
 
-		if (copy_from_sockptr(&mtu, optval, sizeof(u16))) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&mtu, sizeof(mtu), optval, optlen);
+		if (err)
 			break;
-		}
 
 		if (chan->mode == L2CAP_MODE_EXT_FLOWCTL &&
 		    sk->sk_state == BT_CONNECTED)
@@ -1087,10 +1076,9 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 			break;
 		}
 
-		if (copy_from_sockptr(&mode, optval, sizeof(u8))) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&mode, sizeof(mode), optval, optlen);
+		if (err)
 			break;
-		}
 
 		BT_DBG("mode %u", mode);
 
-- 
2.44.0