From patchwork Tue Jan 9 20:55:40 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 10153437 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 1F8A860223 for ; Tue, 9 Jan 2018 21:05:03 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 140352040D for ; Tue, 9 Jan 2018 21:05:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 04FE22434C; Tue, 9 Jan 2018 21:05:03 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED, T_DKIM_INVALID, URIBL_BLACK autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 474EE2040D for ; Tue, 9 Jan 2018 21:05:01 +0000 (UTC) Received: (qmail 11308 invoked by uid 550); 9 Jan 2018 20:57:56 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 9489 invoked from network); 9 Jan 2018 20:57:30 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=FM2z8PafjAhA/L9sC5HMtqa2By/d9zrtd457W6KsFwM=; b=Jhkw7LN/ExR2+A7V2E7AhLUM78nFdR5o9R5BEwY/ehlcZSAkzU4BgGMeqm+R0ZENMe G16EcVGHdQ/YW5Wrj6u74hkSStcj4dD1HEijJS1kgy2I0WH7wCh4hAZOqaqe4AOd6x+F qxFurcDFxK1wojvV5hcEtr76VAimukA/stSEc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=FM2z8PafjAhA/L9sC5HMtqa2By/d9zrtd457W6KsFwM=; b=nYIQxWPqSC/Qar2I8EQlJYlrIQw+Ap332Orb2eYroA3+z0WdRRy131kyWmX92x/Fiv ganXDayIgKdxbfoif+jgl5W34ayxkQMFwBsW7DuzCaLbRwHKuW5/XDQPl1fR9+x1tT+I 5f5LxVK1EkElKkfPGEc0WusyPT+QBXLlQ99DV9czWJz35/HJ56HOnyHo/Hq5MZErlzTP tL+FeQdRZ3dJWqxheTwER8pQydE+aHuBkeq9kLR1464S/NZYS0GPfJFpu71Dyjx82rlc nKpPYcUa8dOnDv/PhInIlhP9iLYxjbrYMWyiPU6IDBqqw2HqmlDLl157wW5qCe984HTy LXPg== X-Gm-Message-State: AKGB3mKOTseiyrm5jcmskDplv2jF6eyl7RmbudbYm/xnFKz5MTbH+6u/ YN4bgjQWuKzcVRLLGCkYTDc2pw== X-Google-Smtp-Source: ACJfBourmumilVxW/1/rK6bj/lyw6eyNEwJnT2Lmo/Y+2PPBoWhyso1pO/jgyI3g5mHm09RGiln7HQ== X-Received: by 10.84.247.137 with SMTP id o9mr16618148pll.194.1515531438909; Tue, 09 Jan 2018 12:57:18 -0800 (PST) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , Jan Kara , linux-ext4@vger.kernel.org, Linus Torvalds , Alexander Viro , Andrew Morton , Andy Lutomirski , Christoph Hellwig , Christoph Lameter , "David S. Miller" , Laura Abbott , Mark Rutland , "Martin K. Petersen" , Paolo Bonzini , Christian Borntraeger , Christoffer Dall , Dave Kleikamp , Jan Kara , Luis de Bethencourt , Marc Zyngier , Rik van Riel , Matthew Garrett , linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Tue, 9 Jan 2018 12:55:40 -0800 Message-Id: <1515531365-37423-12-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1515531365-37423-1-git-send-email-keescook@chromium.org> References: <1515531365-37423-1-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] [PATCH 11/36] ext2: Define usercopy region in ext2_inode_cache slab cache X-Virus-Scanned: ClamAV using ClamSMTP From: David Windsor The ext2 symlink pathnames, stored in struct ext2_inode_info.i_data and therefore contained in the ext2_inode_cache slab cache, need to be copied to/from userspace. cache object allocation: fs/ext2/super.c: ext2_alloc_inode(...): struct ext2_inode_info *ei; ... ei = kmem_cache_alloc(ext2_inode_cachep, GFP_NOFS); ... return &ei->vfs_inode; fs/ext2/ext2.h: EXT2_I(struct inode *inode): return container_of(inode, struct ext2_inode_info, vfs_inode); fs/ext2/namei.c: ext2_symlink(...): ... inode->i_link = (char *)&EXT2_I(inode)->i_data; example usage trace: readlink_copy+0x43/0x70 vfs_readlink+0x62/0x110 SyS_readlinkat+0x100/0x130 fs/namei.c: readlink_copy(..., link): ... copy_to_user(..., link, len); (inlined into vfs_readlink) generic_readlink(dentry, ...): struct inode *inode = d_inode(dentry); const char *link = inode->i_link; ... readlink_copy(..., link); In support of usercopy hardening, this patch defines a region in the ext2_inode_cache slab cache in which userspace copy operations are allowed. This region is known as the slab cache's usercopy region. Slab caches can now check that each dynamically sized copy operation involving cache-managed memory falls entirely within the slab's usercopy region. This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY whitelisting code in the last public patch of grsecurity/PaX based on my understanding of the code. Changes or omissions from the original code are mine and don't reflect the original grsecurity/PaX code. Signed-off-by: David Windsor [kees: adjust commit log, provide usage trace] Cc: Jan Kara Cc: linux-ext4@vger.kernel.org Signed-off-by: Kees Cook Acked-by: Jan Kara --- fs/ext2/super.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/ext2/super.c b/fs/ext2/super.c index 7646818ab266..50b8946c3d1a 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -220,11 +220,13 @@ static void init_once(void *foo) static int __init init_inodecache(void) { - ext2_inode_cachep = kmem_cache_create("ext2_inode_cache", - sizeof(struct ext2_inode_info), - 0, (SLAB_RECLAIM_ACCOUNT| - SLAB_MEM_SPREAD|SLAB_ACCOUNT), - init_once); + ext2_inode_cachep = kmem_cache_create_usercopy("ext2_inode_cache", + sizeof(struct ext2_inode_info), 0, + (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD| + SLAB_ACCOUNT), + offsetof(struct ext2_inode_info, i_data), + sizeof_field(struct ext2_inode_info, i_data), + init_once); if (ext2_inode_cachep == NULL) return -ENOMEM; return 0;