From patchwork Mon Aug 28 21:34:49 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9926277 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 A86FD60383 for ; Mon, 28 Aug 2017 21:37:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9DC1D287CE for ; Mon, 28 Aug 2017 21:37:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 91AFD287DE; Mon, 28 Aug 2017 21:37:58 +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 ECB75287E2 for ; Mon, 28 Aug 2017 21:37:54 +0000 (UTC) Received: (qmail 12243 invoked by uid 550); 28 Aug 2017 21:35:39 -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 12015 invoked from network); 28 Aug 2017 21:35:34 -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=ZZCTRJwpDkZVPOclHxzOkNUiLhC/JhJGmyLmxiRZFcA=; b=jKFan3qBQiq9B9JRZreTDPt1YcHRpTe2T9o9dtineqH/NWxdX5EuB4kNz+SdRqV1o/ 3sgjgLyLbPd45VBm8Yo62+MnAAYTTMGDAxAroZVC35AmDC8zFqlXZlvIFvcX/t+Z+twz DApL3mg7taQ/UI5SXfRFKwH/vajO5fq4spQKs= 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=ZZCTRJwpDkZVPOclHxzOkNUiLhC/JhJGmyLmxiRZFcA=; b=sPXBOw5gl8XooysAY+VEFSbZxnst/LVA4vPJ6ltUat46zgUkJHvQoUwX8VtRuZAb8C pA3Gn02Y8dHKdEBTYY6c4pjGA1Zo8Nf3Zo2FADYkRt5gHPu5AEBj3UgRRL49zU+vXGBy lvjXlE2f2lzVP7rGKB1CV5e3zId9iG5yTL4k4ntDKpWVj1BYoKfbcG5Ma4Ykg7adJd1X rbCO+XGP2sUelHe2CZULsGMfs8hbhtftHbD0PCEZ+38qpbAtCTm03bCPLa+02yLslLAe pFFwdPAqHWQcLHlKljHyBuamKZZxtTsjb273wtzPhloNEjGt7+OmsP0T6TWTxHUO/mEO FpOg== X-Gm-Message-State: AHYfb5jEEPN6zDf/ycEjZ8b9gZzL07mOwJ+rzN0VmHyQzZEPvsHYc0nI tvv2+32W6oy/vzPY X-Received: by 10.99.180.2 with SMTP id s2mr1790135pgf.183.1503956122755; Mon, 28 Aug 2017 14:35:22 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , Jan Kara , linux-ext4@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Mon, 28 Aug 2017 14:34:49 -0700 Message-Id: <1503956111-36652-9-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1503956111-36652-1-git-send-email-keescook@chromium.org> References: <1503956111-36652-1-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] [PATCH v2 08/30] 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 7b1bc9059863..670142cde59d 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -219,11 +219,13 @@ 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;