Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751584AbdFFRsX (ORCPT ); Tue, 6 Jun 2017 13:48:23 -0400 Received: from frisell.zx2c4.com ([192.95.5.64]:38383 "EHLO frisell.zx2c4.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751537AbdFFRsT (ORCPT ); Tue, 6 Jun 2017 13:48:19 -0400 From: "Jason A. Donenfeld" To: "Theodore Ts'o" , Linux Crypto Mailing List , LKML , kernel-hardening@lists.openwall.com, Greg Kroah-Hartman , David Miller , Eric Biggers Cc: "Jason A. Donenfeld" , David Howells , Mimi Zohar , David Safford Subject: [PATCH v4 04/13] security/keys: ensure RNG is seeded before use Date: Tue, 6 Jun 2017 19:47:55 +0200 Message-Id: <20170606174804.31124-5-Jason@zx2c4.com> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20170606174804.31124-1-Jason@zx2c4.com> References: <20170606174804.31124-1-Jason@zx2c4.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3202 Lines: 85 Otherwise, we might use bad random numbers which, particularly in the case of IV generation, could be quite bad. It makes sense to use the synchronous API here, because we're always in process context (as the code is littered with GFP_KERNEL and the like). However, we can't change to using a blocking function in key serial allocation, because this will block booting in some configurations, so here we use the more appropriate get_random_u32, which will use RDRAND if available. Signed-off-by: Jason A. Donenfeld Cc: David Howells Cc: Mimi Zohar Cc: David Safford --- security/keys/encrypted-keys/encrypted.c | 8 +++++--- security/keys/key.c | 16 ++++++++-------- 2 files changed, 13 insertions(+), 11 deletions(-) diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c index 0010955d7876..d51a28fc5cd5 100644 --- a/security/keys/encrypted-keys/encrypted.c +++ b/security/keys/encrypted-keys/encrypted.c @@ -777,10 +777,12 @@ static int encrypted_init(struct encrypted_key_payload *epayload, __ekey_init(epayload, format, master_desc, datalen); if (!hex_encoded_iv) { - get_random_bytes(epayload->iv, ivsize); + ret = get_random_bytes_wait(epayload->iv, ivsize); + if (unlikely(ret)) + return ret; - get_random_bytes(epayload->decrypted_data, - epayload->decrypted_datalen); + ret = get_random_bytes_wait(epayload->decrypted_data, + epayload->decrypted_datalen); } else ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); return ret; diff --git a/security/keys/key.c b/security/keys/key.c index 455c04d80bbb..b72078e532f2 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -134,17 +134,15 @@ void key_user_put(struct key_user *user) * Allocate a serial number for a key. These are assigned randomly to avoid * security issues through covert channel problems. */ -static inline void key_alloc_serial(struct key *key) +static inline int key_alloc_serial(struct key *key) { struct rb_node *parent, **p; struct key *xkey; - /* propose a random serial number and look for a hole for it in the - * serial number tree */ + /* propose a non-negative random serial number and look for a hole for + * it in the serial number tree */ do { - get_random_bytes(&key->serial, sizeof(key->serial)); - - key->serial >>= 1; /* negative numbers are not permitted */ + key->serial = get_random_u32() >> 1; } while (key->serial < 3); spin_lock(&key_serial_lock); @@ -170,7 +168,7 @@ static inline void key_alloc_serial(struct key *key) rb_insert_color(&key->serial_node, &key_serial_tree); spin_unlock(&key_serial_lock); - return; + return 0; /* we found a key with the proposed serial number - walk the tree from * that point looking for the next unused serial number */ @@ -314,7 +312,9 @@ struct key *key_alloc(struct key_type *type, const char *desc, /* publish the key by giving it a serial number */ atomic_inc(&user->nkeys); - key_alloc_serial(key); + ret = key_alloc_serial(key); + if (ret < 0) + goto security_error; error: return key; -- 2.13.0