From patchwork Wed Sep 20 20:45:14 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9962437 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 8B27B60208 for ; Wed, 20 Sep 2017 20:48:06 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7C81C29226 for ; Wed, 20 Sep 2017 20:48:06 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 713B229229; Wed, 20 Sep 2017 20:48:06 +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 ED46629226 for ; Wed, 20 Sep 2017 20:48:04 +0000 (UTC) Received: (qmail 3638 invoked by uid 550); 20 Sep 2017 20:46:21 -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 3495 invoked from network); 20 Sep 2017 20:46:17 -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=LvcQspsIR0cZ09igwnjHXzULMGq3Dr6LW9yWsRsqMUs=; b=EoCb4hwO5OkWUgCqdkj6LdxwhefJQHd/0AAX+/seNjy8OztA6nKzzVA1V8FxnD0t/K cdCnArv5YRN9C2z0URakmChOLSHkz+FgpNbQhL/2N6TQGHA/YSgXA0PXUrlpybXxuBNm YofEP/WpFtXAJSGYo6CXfY0cpMhRJf8HtGzkc= 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=LvcQspsIR0cZ09igwnjHXzULMGq3Dr6LW9yWsRsqMUs=; b=jz0bTwarO9ri/eFpyQY0kpqPqJ0sQWDXle+740C9bE/hjIoWFB9WnpxxSCtOeL4emm VbMoJYaj+8EArYDGQn7EKf8+5iqLu22Cp116/vpt9Sj+jc/U2jjj5U+7Nc7zIHyuqiN8 m/LhP+4x67R73pU7IJ8yz3P1CFVdFSQWI3uSU+YBuTXs/jsLtWnXAjLofAMmb0jF2cm/ IPTA+nUAl5pIY3wdTZThxkXhh04c50k2Awd8TjBiHBQqxLR2pDbcl7QzSu/c5wOg/F8m Xc+HkCKObNpu9MHyOvmYsCjw00Gxy/MGkW80sQFr78HeozkOr2l9FXiKy+XrQ8UOiEJC ULcg== X-Gm-Message-State: AHPjjUiDvKVLfp3wRr0AWYKHp/XFf234tEslvvKyFbw70NH8z2cv2ujH UG6HLWnTIw5DpMmRvns9UHuGKA== X-Google-Smtp-Source: AOwi7QBliiflupQIqDjOeU6Guyk7gsp7PfnS+t6H7cX5J1nN7fdMVhelaWdTXOECuREG6yPlGBX29A== X-Received: by 10.101.88.203 with SMTP id e11mr3306923pgu.95.1505940365703; Wed, 20 Sep 2017 13:46:05 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , Jan Kara , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Wed, 20 Sep 2017 13:45:14 -0700 Message-Id: <1505940337-79069-9-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1505940337-79069-1-git-send-email-keescook@chromium.org> References: <1505940337-79069-1-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] [PATCH v3 08/31] 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 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 1458706bd2ec..789c29987b36 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;