From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELu8zyln29F/+ArZy7Z0wMwd0FEYapHf2fiH888H6hFqxiWwSgywMRK1upeL08JrtwdCgCmX ARC-Seal: i=1; a=rsa-sha256; t=1520915423; cv=none; d=google.com; s=arc-20160816; b=vmz+i5ZE0U9kDKNv42aiu6nnfSfxl6sj0z9Rb694jz6BFvGJS9Fd7b6VmOOjPAoISt RCbiVsnrHbpC9vbivmzkKAKX/1h0QanS4rEkQB86k6R3AMarHCiuUEKjUTBS0mqq6XoY 4tNz8DjAEryNtE1CyedSLsHVUeSp/Kwb8t4kMEZ/+zjkYKvGd7R2QK+c9RKL1GvXORSH r0LcvnkTA+i4pxgdAF9TwBIbgXuD1q0+DA1JU5grAbJzBaCMOCWjcr2/TSuRmbg0f5+r c1B9Y7IBs1t6bYu2UQXwzkjfXPidT/3fI54iDaStHnVRCMEPevjgF+heAS6zo0TvD6A0 5WBQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=message-id:date:subject:cc:to:from:dkim-signature:delivered-to :list-id:list-subscribe:list-unsubscribe:list-help:list-post :precedence:mailing-list:arc-authentication-results; bh=3m64m4812TaCibAtDMzmJiivBFzUMendi6gNta4oOlM=; b=EDMiNIIQM/UTV4mtSdA+G2VvEmeM7bRkMWYbZuNhwKKiB/zwV16+U/GEzM/2zVB+ZI wOPSoEb0ab85SpNQ1C9wXNECUqMLtQL788raOiiupvlfKFjfSkpIUi09jllsfEn7s6q5 Gs01iBYOTOs89UjJ+0AplDK6SSpLY3G2bYrUXR/hpLcLtqLWUIlI6RhXA0kNRf/uUtqD qtnWrSLDxiEZhFvQ3F6mG3AL2+I3UhR1ZAO3YKKDzvCNII6swuOldyfiO7wESMNyzjUP e+HU7bWTnc+B73CFSuvC9kUJmvPW6Pod+xj3xF2DGMuVF/H638515hbRryQN8iN2Dj7r OIjg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@tycho-ws.20150623.gappssmtp.com header.s=20150623 header.b=dX53qXgS; spf=pass (google.com: domain of kernel-hardening-return-12492-gregkh=linuxfoundation.org@lists.openwall.com designates 195.42.179.200 as permitted sender) smtp.mailfrom=kernel-hardening-return-12492-gregkh=linuxfoundation.org@lists.openwall.com Authentication-Results: mx.google.com; dkim=pass header.i=@tycho-ws.20150623.gappssmtp.com header.s=20150623 header.b=dX53qXgS; spf=pass (google.com: domain of kernel-hardening-return-12492-gregkh=linuxfoundation.org@lists.openwall.com designates 195.42.179.200 as permitted sender) smtp.mailfrom=kernel-hardening-return-12492-gregkh=linuxfoundation.org@lists.openwall.com Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm List-Post: List-Help: List-Unsubscribe: List-Subscribe: From: Tycho Andersen To: David Howells Cc: keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, Tycho Andersen , James Morris , "Serge E. Hallyn" , "Jason A . Donenfeld" Subject: [PATCH 1/2] big key: get rid of stack array allocation Date: Mon, 12 Mar 2018 22:29:06 -0600 Message-Id: <20180313042907.29598-1-tycho@tycho.ws> X-Mailer: git-send-email 2.15.1 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594795410426531293?= X-GMAIL-MSGID: =?utf-8?q?1594795410426531293?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: We're interested in getting rid of all of the stack allocated arrays in the kernel [1]. This patch removes one in keys by switching to malloc/free. Note that we use kzalloc, to avoid leaking the nonce. I'm not sure this is really necessary, but extra paranoia seems prudent. Manually tested using the program from the add_key man page to trigger big_key. [1]: https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Tycho Andersen CC: David Howells CC: James Morris CC: "Serge E. Hallyn" CC: Jason A. Donenfeld --- security/keys/big_key.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/security/keys/big_key.c b/security/keys/big_key.c index fa728f662a6f..70f9f785c59d 100644 --- a/security/keys/big_key.c +++ b/security/keys/big_key.c @@ -108,13 +108,18 @@ static int big_key_crypt(enum big_key_op op, struct big_key_buf *buf, size_t dat * an .update function, so there's no chance we'll wind up reusing the * key to encrypt updated data. Simply put: one key, one encryption. */ - u8 zero_nonce[crypto_aead_ivsize(big_key_aead)]; + u8 *zero_nonce; + + zero_nonce = kzalloc(crypto_aead_ivsize(big_key_aead), GFP_KERNEL); + if (!zero_nonce) + return -ENOMEM; aead_req = aead_request_alloc(big_key_aead, GFP_KERNEL); - if (!aead_req) + if (!aead_req) { + kfree(zero_nonce); return -ENOMEM; + } - memset(zero_nonce, 0, sizeof(zero_nonce)); aead_request_set_crypt(aead_req, buf->sg, buf->sg, datalen, zero_nonce); aead_request_set_callback(aead_req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL); aead_request_set_ad(aead_req, 0); @@ -131,6 +136,7 @@ static int big_key_crypt(enum big_key_op op, struct big_key_buf *buf, size_t dat error: mutex_unlock(&big_key_aead_lock); aead_request_free(aead_req); + kzfree(zero_nonce); return ret; } -- 2.15.1