Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751929AbdFJDAU (ORCPT ); Fri, 9 Jun 2017 23:00:20 -0400 Received: from frisell.zx2c4.com ([192.95.5.64]:52679 "EHLO frisell.zx2c4.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751860AbdFJC7h (ORCPT ); Fri, 9 Jun 2017 22:59:37 -0400 From: "Jason A. Donenfeld" To: linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Cc: "Jason A. Donenfeld" , Marcel Holtmann , Gustavo Padovan , Johan Hedberg , linux-bluetooth@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH 5/6] bluetooth/smp: use constant time memory comparison for secret values Date: Sat, 10 Jun 2017 04:59:11 +0200 Message-Id: <20170610025912.6499-6-Jason@zx2c4.com> In-Reply-To: <20170610025912.6499-1-Jason@zx2c4.com> References: <20170610025912.6499-1-Jason@zx2c4.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5533 Lines: 190 This file is filled with complex cryptography. Thus, the comparisons of MACs and secret keys and curve points and so forth should not add timing attacks, which could either result in a direct forgery, or, given the complexity, some other type of attack. Signed-off-by: Jason A. Donenfeld Cc: Marcel Holtmann Cc: Gustavo Padovan Cc: Johan Hedberg Cc: linux-bluetooth@vger.kernel.org Cc: stable@vger.kernel.org --- net/bluetooth/smp.c | 39 ++++++++++++++++++++------------------- 1 file changed, 20 insertions(+), 19 deletions(-) diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c index 14585edc9439..a0ef89772c36 100644 --- a/net/bluetooth/smp.c +++ b/net/bluetooth/smp.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include @@ -523,7 +524,7 @@ bool smp_irk_matches(struct hci_dev *hdev, const u8 irk[16], if (err) return false; - return !memcmp(bdaddr->b, hash, 3); + return !crypto_memneq(bdaddr->b, hash, 3); } int smp_generate_rpa(struct hci_dev *hdev, const u8 irk[16], bdaddr_t *rpa) @@ -579,7 +580,7 @@ int smp_generate_oob(struct hci_dev *hdev, u8 hash[16], u8 rand[16]) /* This is unlikely, but we need to check that * we didn't accidentially generate a debug key. */ - if (memcmp(smp->local_sk, debug_sk, 32)) + if (crypto_memneq(smp->local_sk, debug_sk, 32)) break; } smp->debug_key = false; @@ -993,7 +994,7 @@ static u8 smp_random(struct smp_chan *smp) if (ret) return SMP_UNSPECIFIED; - if (memcmp(smp->pcnf, confirm, sizeof(smp->pcnf)) != 0) { + if (crypto_memneq(smp->pcnf, confirm, sizeof(smp->pcnf))) { BT_ERR("Pairing failed (confirmation values mismatch)"); return SMP_CONFIRM_FAILED; } @@ -1512,7 +1513,7 @@ static u8 sc_passkey_round(struct smp_chan *smp, u8 smp_op) smp->rrnd, r, cfm)) return SMP_UNSPECIFIED; - if (memcmp(smp->pcnf, cfm, 16)) + if (crypto_memneq(smp->pcnf, cfm, 16)) return SMP_CONFIRM_FAILED; smp->passkey_round++; @@ -1908,7 +1909,7 @@ static u8 sc_send_public_key(struct smp_chan *smp) /* This is unlikely, but we need to check that * we didn't accidentially generate a debug key. */ - if (memcmp(smp->local_sk, debug_sk, 32)) + if (crypto_memneq(smp->local_sk, debug_sk, 32)) break; } } @@ -2176,7 +2177,7 @@ static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb) if (err) return SMP_UNSPECIFIED; - if (memcmp(smp->pcnf, cfm, 16)) + if (crypto_memneq(smp->pcnf, cfm, 16)) return SMP_CONFIRM_FAILED; } else { smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd), @@ -2660,7 +2661,7 @@ static int smp_cmd_public_key(struct l2cap_conn *conn, struct sk_buff *skb) if (err) return SMP_UNSPECIFIED; - if (memcmp(cfm.confirm_val, smp->pcnf, 16)) + if (crypto_memneq(cfm.confirm_val, smp->pcnf, 16)) return SMP_CONFIRM_FAILED; } @@ -2693,7 +2694,7 @@ static int smp_cmd_public_key(struct l2cap_conn *conn, struct sk_buff *skb) else hcon->pending_sec_level = BT_SECURITY_FIPS; - if (!memcmp(debug_pk, smp->remote_pk, 64)) + if (!crypto_memneq(debug_pk, smp->remote_pk, 64)) set_bit(SMP_FLAG_DEBUG_KEY, &smp->flags); if (smp->method == DSP_PASSKEY) { @@ -2792,7 +2793,7 @@ static int smp_cmd_dhkey_check(struct l2cap_conn *conn, struct sk_buff *skb) if (err) return SMP_UNSPECIFIED; - if (memcmp(check->e, e, 16)) + if (crypto_memneq(check->e, e, 16)) return SMP_DHKEY_CHECK_FAILED; if (!hcon->out) { @@ -3506,10 +3507,10 @@ static int __init test_debug_key(void) if (!generate_ecdh_keys(pk, sk)) return -EINVAL; - if (memcmp(sk, debug_sk, 32)) + if (crypto_memneq(sk, debug_sk, 32)) return -EINVAL; - if (memcmp(pk, debug_pk, 64)) + if (crypto_memneq(pk, debug_pk, 64)) return -EINVAL; return 0; @@ -3529,7 +3530,7 @@ static int __init test_ah(struct crypto_cipher *tfm_aes) if (err) return err; - if (memcmp(res, exp, 3)) + if (crypto_memneq(res, exp, 3)) return -EINVAL; return 0; @@ -3559,7 +3560,7 @@ static int __init test_c1(struct crypto_cipher *tfm_aes) if (err) return err; - if (memcmp(res, exp, 16)) + if (crypto_memneq(res, exp, 16)) return -EINVAL; return 0; @@ -3584,7 +3585,7 @@ static int __init test_s1(struct crypto_cipher *tfm_aes) if (err) return err; - if (memcmp(res, exp, 16)) + if (crypto_memneq(res, exp, 16)) return -EINVAL; return 0; @@ -3616,7 +3617,7 @@ static int __init test_f4(struct crypto_shash *tfm_cmac) if (err) return err; - if (memcmp(res, exp, 16)) + if (crypto_memneq(res, exp, 16)) return -EINVAL; return 0; @@ -3650,10 +3651,10 @@ static int __init test_f5(struct crypto_shash *tfm_cmac) if (err) return err; - if (memcmp(mackey, exp_mackey, 16)) + if (crypto_memneq(mackey, exp_mackey, 16)) return -EINVAL; - if (memcmp(ltk, exp_ltk, 16)) + if (crypto_memneq(ltk, exp_ltk, 16)) return -EINVAL; return 0; @@ -3686,7 +3687,7 @@ static int __init test_f6(struct crypto_shash *tfm_cmac) if (err) return err; - if (memcmp(res, exp, 16)) + if (crypto_memneq(res, exp, 16)) return -EINVAL; return 0; @@ -3740,7 +3741,7 @@ static int __init test_h6(struct crypto_shash *tfm_cmac) if (err) return err; - if (memcmp(res, exp, 16)) + if (crypto_memneq(res, exp, 16)) return -EINVAL; return 0; -- 2.13.1