Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753208AbdFLP3e (ORCPT ); Mon, 12 Jun 2017 11:29:34 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:39926 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752510AbdFLP3b (ORCPT ); Mon, 12 Jun 2017 11:29:31 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski , Herbert Xu , Mimi Zohar , Eric Biggers , David Howells , James Morris Subject: [PATCH 4.11 040/150] KEYS: encrypted: avoid encrypting/decrypting stack buffers Date: Mon, 12 Jun 2017 17:24:07 +0200 Message-Id: <20170612152521.183221973@linuxfoundation.org> X-Mailer: git-send-email 2.13.1 In-Reply-To: <20170612152519.404936272@linuxfoundation.org> References: <20170612152519.404936272@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3482 Lines: 104 4.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers commit e9ff56ac352446f55141aaef1553cee662b2e310 upstream. Since v4.9, the crypto API cannot (normally) be used to encrypt/decrypt stack buffers because the stack may be virtually mapped. Fix this for the padding buffers in encrypted-keys by using ZERO_PAGE for the encryption padding and by allocating a temporary heap buffer for the decryption padding. Tested with CONFIG_DEBUG_SG=y: keyctl new_session keyctl add user master "abcdefghijklmnop" @s keyid=$(keyctl add encrypted desc "new user:master 25" @s) datablob="$(keyctl pipe $keyid)" keyctl unlink $keyid keyid=$(keyctl add encrypted desc "load $datablob" @s) datablob2="$(keyctl pipe $keyid)" [ "$datablob" = "$datablob2" ] && echo "Success!" Cc: Andy Lutomirski Cc: Herbert Xu Cc: Mimi Zohar Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman --- security/keys/encrypted-keys/encrypted.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) --- a/security/keys/encrypted-keys/encrypted.c +++ b/security/keys/encrypted-keys/encrypted.c @@ -480,12 +480,9 @@ static int derived_key_encrypt(struct en struct skcipher_request *req; unsigned int encrypted_datalen; u8 iv[AES_BLOCK_SIZE]; - unsigned int padlen; - char pad[16]; int ret; encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); - padlen = encrypted_datalen - epayload->decrypted_datalen; req = init_skcipher_req(derived_key, derived_keylen); ret = PTR_ERR(req); @@ -493,11 +490,10 @@ static int derived_key_encrypt(struct en goto out; dump_decrypted_data(epayload); - memset(pad, 0, sizeof pad); sg_init_table(sg_in, 2); sg_set_buf(&sg_in[0], epayload->decrypted_data, epayload->decrypted_datalen); - sg_set_buf(&sg_in[1], pad, padlen); + sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0); sg_init_table(sg_out, 1); sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); @@ -584,9 +580,14 @@ static int derived_key_decrypt(struct en struct skcipher_request *req; unsigned int encrypted_datalen; u8 iv[AES_BLOCK_SIZE]; - char pad[16]; + u8 *pad; int ret; + /* Throwaway buffer to hold the unused zero padding at the end */ + pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL); + if (!pad) + return -ENOMEM; + encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); req = init_skcipher_req(derived_key, derived_keylen); ret = PTR_ERR(req); @@ -594,13 +595,12 @@ static int derived_key_decrypt(struct en goto out; dump_encrypted_data(epayload, encrypted_datalen); - memset(pad, 0, sizeof pad); sg_init_table(sg_in, 1); sg_init_table(sg_out, 2); sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); sg_set_buf(&sg_out[0], epayload->decrypted_data, epayload->decrypted_datalen); - sg_set_buf(&sg_out[1], pad, sizeof pad); + sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE); memcpy(iv, epayload->iv, sizeof(iv)); skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); @@ -612,6 +612,7 @@ static int derived_key_decrypt(struct en goto out; dump_decrypted_data(epayload); out: + kfree(pad); return ret; }