[PATCH v1] Bluetooth: Enforce key size of 16 bytes on FIPS level

[Archie Pusaka <apusaka@google.com>]

From: Archie Pusaka <apusaka@chromium.org>

According to the spec Ver 5.2, Vol 3, Part C, Sec 5.2.2.8:
Device in security mode 4 level 4 shall enforce:
128-bit equivalent strength for link and encryption keys required
using FIPS approved algorithms (E0 not allowed, SAFER+ not allowed,
and P-192 not allowed; encryption key not shortened)

This patch rejects connection with key size below 16 for FIPS level
services.

Signed-off-by: Archie Pusaka <apusaka@chromium.org>
Reviewed-by: Alain Michaud <alainm@chromium.org>

---

 net/bluetooth/l2cap_core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index ade83e224567..306616ec26e6 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -1515,8 +1515,13 @@ static bool l2cap_check_enc_key_size(struct hci_conn *hcon)
 	 * that have no key size requirements. Ensure that the link is
 	 * actually encrypted before enforcing a key size.
 	 */
+	int min_key_size = hcon->hdev->min_enc_key_size;
+
+	if (hcon->sec_level == BT_SECURITY_FIPS)
+		min_key_size = 16;
+
 	return (!test_bit(HCI_CONN_ENCRYPT, &hcon->flags) ||
-		hcon->enc_key_size >= hcon->hdev->min_enc_key_size);
+		hcon->enc_key_size >= min_key_size);
 }
 
 static void l2cap_do_start(struct l2cap_chan *chan)
-- 
2.28.0.681.g6f77f65b4e-goog