1 files changed, 119 insertions, 19 deletions

diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 659371a..3d0f7d2 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -33,6 +33,9 @@
 #include "ecc.h"
 #include "smp.h"
 
+#define SMP_DEV(hdev) \
+	((struct smp_dev *)((struct l2cap_chan *)((hdev)->smp_data))->data)
+
 /* Low-level debug macros to be used for stuff that we don't want
  * accidentially in dmesg, i.e. the values of the various crypto keys
  * and the inputs & outputs of crypto functions.
@@ -81,6 +84,9 @@ struct smp_dev {
 	u8			local_rand[16];
 	bool			debug_key;
 
+	u8			min_key_size;
+	u8			max_key_size;
+
 	struct crypto_blkcipher	*tfm_aes;
 	struct crypto_hash	*tfm_cmac;
 };
@@ -708,7 +714,7 @@ static void build_pairing_cmd(struct l2cap_conn *conn,
 	if (rsp == NULL) {
 		req->io_capability = conn->hcon->io_capability;
 		req->oob_flag = oob_flag;
-		req->max_key_size = SMP_MAX_ENC_KEY_SIZE;
+		req->max_key_size = SMP_DEV(hdev)->max_key_size;
 		req->init_key_dist = local_dist;
 		req->resp_key_dist = remote_dist;
 		req->auth_req = (authreq & AUTH_REQ_MASK(hdev));
@@ -719,7 +725,7 @@ static void build_pairing_cmd(struct l2cap_conn *conn,
 
 	rsp->io_capability = conn->hcon->io_capability;
 	rsp->oob_flag = oob_flag;
-	rsp->max_key_size = SMP_MAX_ENC_KEY_SIZE;
+	rsp->max_key_size = SMP_DEV(hdev)->max_key_size;
 	rsp->init_key_dist = req->init_key_dist & remote_dist;
 	rsp->resp_key_dist = req->resp_key_dist & local_dist;
 	rsp->auth_req = (authreq & AUTH_REQ_MASK(hdev));
@@ -730,10 +736,11 @@ static void build_pairing_cmd(struct l2cap_conn *conn,
 static u8 check_enc_key_size(struct l2cap_conn *conn, __u8 max_key_size)
 {
 	struct l2cap_chan *chan = conn->smp;
+	struct hci_dev *hdev = conn->hcon->hdev;
 	struct smp_chan *smp = chan->data;
 
-	if ((max_key_size > SMP_MAX_ENC_KEY_SIZE) ||
-	    (max_key_size < SMP_MIN_ENC_KEY_SIZE))
+	if (max_key_size > SMP_DEV(hdev)->max_key_size ||
+	    max_key_size < SMP_MIN_ENC_KEY_SIZE)
 		return SMP_ENC_KEY_SIZE;
 
 	smp->enc_key_size = max_key_size;
@@ -997,13 +1004,10 @@ static u8 smp_random(struct smp_chan *smp)
 
 		smp_s1(smp->tfm_aes, smp->tk, smp->rrnd, smp->prnd, stk);
 
-		memset(stk + smp->enc_key_size, 0,
-		       SMP_MAX_ENC_KEY_SIZE - smp->enc_key_size);
-
 		if (test_and_set_bit(HCI_CONN_ENCRYPT_PEND, &hcon->flags))
 			return SMP_UNSPECIFIED;
 
-		hci_le_start_enc(hcon, ediv, rand, stk);
+		hci_le_start_enc(hcon, ediv, rand, stk, smp->enc_key_size);
 		hcon->enc_key_size = smp->enc_key_size;
 		set_bit(HCI_CONN_STK_ENCRYPT, &hcon->flags);
 	} else {
@@ -1016,9 +1020,6 @@ static u8 smp_random(struct smp_chan *smp)
 
 		smp_s1(smp->tfm_aes, smp->tk, smp->prnd, smp->rrnd, stk);
 
-		memset(stk + smp->enc_key_size, 0,
-		       SMP_MAX_ENC_KEY_SIZE - smp->enc_key_size);
-
 		if (hcon->pending_sec_level == BT_SECURITY_HIGH)
 			auth = 1;
 		else
@@ -1156,9 +1157,6 @@ static void sc_add_ltk(struct smp_chan *smp)
 	else
 		auth = 0;
 
-	memset(smp->tk + smp->enc_key_size, 0,
-	       SMP_MAX_ENC_KEY_SIZE - smp->enc_key_size);
-
 	smp->ltk = hci_add_ltk(hcon->hdev, &hcon->dst, hcon->dst_type,
 			       key_type, auth, smp->tk, smp->enc_key_size,
 			       0, 0);
@@ -1280,7 +1278,14 @@ static void smp_distribute_keys(struct smp_chan *smp)
 		__le16 ediv;
 		__le64 rand;
 
-		get_random_bytes(enc.ltk, sizeof(enc.ltk));
+		/* Make sure we generate only the significant amount of
+		 * bytes based on the encryption key size, and set the rest
+		 * of the value to zeroes.
+		 */
+		get_random_bytes(enc.ltk, smp->enc_key_size);
+		memset(enc.ltk + smp->enc_key_size, 0,
+		       sizeof(enc.ltk) - smp->enc_key_size);
+
 		get_random_bytes(&ediv, sizeof(ediv));
 		get_random_bytes(&rand, sizeof(rand));
 
@@ -1700,7 +1705,7 @@ static void build_bredr_pairing_cmd(struct smp_chan *smp,
 
 		req->init_key_dist   = local_dist;
 		req->resp_key_dist   = remote_dist;
-		req->max_key_size    = SMP_MAX_ENC_KEY_SIZE;
+		req->max_key_size    = conn->hcon->enc_key_size;
 
 		smp->remote_key_dist = remote_dist;
 
@@ -1709,7 +1714,7 @@ static void build_bredr_pairing_cmd(struct smp_chan *smp,
 
 	memset(rsp, 0, sizeof(*rsp));
 
-	rsp->max_key_size    = SMP_MAX_ENC_KEY_SIZE;
+	rsp->max_key_size    = conn->hcon->enc_key_size;
 	rsp->init_key_dist   = req->init_key_dist & remote_dist;
 	rsp->resp_key_dist   = req->resp_key_dist & local_dist;
 
@@ -2202,7 +2207,7 @@ static bool smp_ltk_encrypt(struct l2cap_conn *conn, u8 sec_level)
 	if (test_and_set_bit(HCI_CONN_ENCRYPT_PEND, &hcon->flags))
 		return true;
 
-	hci_le_start_enc(hcon, key->ediv, key->rand, key->val);
+	hci_le_start_enc(hcon, key->ediv, key->rand, key->val, key->enc_size);
 	hcon->enc_key_size = key->enc_size;
 
 	/* We never store STKs for master role, so clear this flag */
@@ -2750,7 +2755,7 @@ static int smp_cmd_dhkey_check(struct l2cap_conn *conn, struct sk_buff *skb)
 	sc_add_ltk(smp);
 
 	if (hcon->out) {
-		hci_le_start_enc(hcon, 0, 0, smp->tk);
+		hci_le_start_enc(hcon, 0, 0, smp->tk, smp->enc_key_size);
 		hcon->enc_key_size = smp->enc_key_size;
 	}
 
@@ -3132,6 +3137,8 @@ static struct l2cap_chan *smp_add_cid(struct hci_dev *hdev, u16 cid)
 
 	smp->tfm_aes = tfm_aes;
 	smp->tfm_cmac = tfm_cmac;
+	smp->min_key_size = SMP_MIN_ENC_KEY_SIZE;
+	smp->max_key_size = SMP_MAX_ENC_KEY_SIZE;
 
 create_chan:
 	chan = l2cap_chan_create();
@@ -3254,6 +3261,94 @@ static const struct file_operations force_bredr_smp_fops = {
 	.llseek		= default_llseek,
 };
 
+static ssize_t le_min_key_size_read(struct file *file,
+				     char __user *user_buf,
+				     size_t count, loff_t *ppos)
+{
+	struct hci_dev *hdev = file->private_data;
+	char buf[4];
+
+	snprintf(buf, sizeof(buf), "%2u\n", SMP_DEV(hdev)->min_key_size);
+
+	return simple_read_from_buffer(user_buf, count, ppos, buf, strlen(buf));
+}
+
+static ssize_t le_min_key_size_write(struct file *file,
+				      const char __user *user_buf,
+				      size_t count, loff_t *ppos)
+{
+	struct hci_dev *hdev = file->private_data;
+	char buf[32];
+	size_t buf_size = min(count, (sizeof(buf) - 1));
+	u8 key_size;
+
+	if (copy_from_user(buf, user_buf, buf_size))
+		return -EFAULT;
+
+	buf[buf_size] = '\0';
+
+	sscanf(buf, "%hhu", &key_size);
+
+	if (key_size > SMP_DEV(hdev)->max_key_size ||
+	    key_size < SMP_MIN_ENC_KEY_SIZE)
+		return -EINVAL;
+
+	SMP_DEV(hdev)->min_key_size = key_size;
+
+	return count;
+}
+
+static const struct file_operations le_min_key_size_fops = {
+	.open		= simple_open,
+	.read		= le_min_key_size_read,
+	.write		= le_min_key_size_write,
+	.llseek		= default_llseek,
+};
+
+static ssize_t le_max_key_size_read(struct file *file,
+				     char __user *user_buf,
+				     size_t count, loff_t *ppos)
+{
+	struct hci_dev *hdev = file->private_data;
+	char buf[4];
+
+	snprintf(buf, sizeof(buf), "%2u\n", SMP_DEV(hdev)->max_key_size);
+
+	return simple_read_from_buffer(user_buf, count, ppos, buf, strlen(buf));
+}
+
+static ssize_t le_max_key_size_write(struct file *file,
+				      const char __user *user_buf,
+				      size_t count, loff_t *ppos)
+{
+	struct hci_dev *hdev = file->private_data;
+	char buf[32];
+	size_t buf_size = min(count, (sizeof(buf) - 1));
+	u8 key_size;
+
+	if (copy_from_user(buf, user_buf, buf_size))
+		return -EFAULT;
+
+	buf[buf_size] = '\0';
+
+	sscanf(buf, "%hhu", &key_size);
+
+	if (key_size > SMP_MAX_ENC_KEY_SIZE ||
+	    key_size < SMP_DEV(hdev)->min_key_size)
+		return -EINVAL;
+
+	SMP_DEV(hdev)->max_key_size = key_size;
+
+	return count;
+}
+
+static const struct file_operations le_max_key_size_fops = {
+	.open		= simple_open,
+	.read		= le_max_key_size_read,
+	.write		= le_max_key_size_write,
+	.llseek		= default_llseek,
+};
+
 int smp_register(struct hci_dev *hdev)
 {
 	struct l2cap_chan *chan;
@@ -3278,6 +3373,11 @@ int smp_register(struct hci_dev *hdev)
 
 	hdev->smp_data = chan;
 
+	debugfs_create_file("le_min_key_size", 0644, hdev->debugfs, hdev,
+			    &le_min_key_size_fops);
+	debugfs_create_file("le_max_key_size", 0644, hdev->debugfs, hdev,
+			    &le_max_key_size_fops);
+
 	/* If the controller does not support BR/EDR Secure Connections
 	 * feature, then the BR/EDR SMP channel shall not be present.
 	 *