From patchwork Wed Sep 20 20:45:13 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9962429 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 2944C60208 for ; Wed, 20 Sep 2017 20:47:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1B8AC29226 for ; Wed, 20 Sep 2017 20:47:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1013A29229; Wed, 20 Sep 2017 20:47:45 +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 0CF8129227 for ; Wed, 20 Sep 2017 20:47:43 +0000 (UTC) Received: (qmail 3580 invoked by uid 550); 20 Sep 2017 20:46:19 -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 3462 invoked from network); 20 Sep 2017 20:46:16 -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=KHkA7gLl/RRGwjgOyKwgdPKfIPgF/zMmJeyAmhW6qOw=; b=fGxlDpm3vc2fA/Jp5Y2utCd8pLahnUqHH5urnUO7T33XIdpYnf5EunhApaWtZvFXBZ PP+lhfzIhN9MC0fnMUrQ9qt/JSve+OY+MsYnT/FJhB5yMZzXWXge3oL7ZWAxcNwbq2qu 3SKnK0rXsWfG0Ow1+CiA5mroMmV9Rrhn3IR/Q= 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=KHkA7gLl/RRGwjgOyKwgdPKfIPgF/zMmJeyAmhW6qOw=; b=GtY96J8sc8RuzjKPeVusYFBFHlJusSaFz5h4/q8HlRqHUp+0QGRtSLx/C26ApyK8uD 8fW/346NzzO+Rm7dp7GD351xQpUHoEjPrsaFqvWSZJhf+s2vOcjVLTmEZrFBHgOSkfGV yhSQNhNmebkh0hc63TySUGP7/d6QfGMrgfXCxN6oKJL05zh7T04AVp+o25GR/QZCz2nN EWbaaUear06+bSJ0XWmiR1R75bmMikzAsDqrTPUCBSPRXXCM8e8DLHamnsXLtKLA+czG npQRa9Wn/6N7PM8K94yokRYbvVMdSsv1y0l8UtiY0bTQOgkE6H7Q5K53xHIb084NMFfv 0Yaw== X-Gm-Message-State: AHPjjUhDSDZ5hBnyRojfj3nY1y+O6ZjB0GQlT+dc+3CJOWdtIFRwVTh5 tKqpczSHAEc4rwvaSjlGabP2GQ== X-Google-Smtp-Source: AOwi7QBE2T8Sem0JxX+dZ9g2uiwe37WR/RLJbYDb7rpoqIGffREbz1I7t/Lcwl6Yfi31ksHmVR+rSg== X-Received: by 10.98.211.200 with SMTP id z69mr3328748pfk.112.1505940364314; Wed, 20 Sep 2017 13:46:04 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , "Theodore Ts'o" , Andreas Dilger , 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 13:45:13 -0700 Message-Id: <1505940337-79069-8-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 07/31] ext4: Define usercopy region in ext4_inode_cache slab cache X-Virus-Scanned: ClamAV using ClamSMTP From: David Windsor The ext4 symlink pathnames, stored in struct ext4_inode_info.i_data and therefore contained in the ext4_inode_cache slab cache, need to be copied to/from userspace. cache object allocation: fs/ext4/super.c: ext4_alloc_inode(...): struct ext4_inode_info *ei; ... ei = kmem_cache_alloc(ext4_inode_cachep, GFP_NOFS); ... return &ei->vfs_inode; include/trace/events/ext4.h: #define EXT4_I(inode) \ (container_of(inode, struct ext4_inode_info, vfs_inode)) fs/ext4/namei.c: ext4_symlink(...): ... inode->i_link = (char *)&EXT4_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 ext4_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: "Theodore Ts'o" Cc: Andreas Dilger Cc: linux-ext4@vger.kernel.org Signed-off-by: Kees Cook --- fs/ext4/super.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index b104096fce9e..b5d393321b7b 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1036,11 +1036,13 @@ static void init_once(void *foo) static int __init init_inodecache(void) { - ext4_inode_cachep = kmem_cache_create("ext4_inode_cache", - sizeof(struct ext4_inode_info), - 0, (SLAB_RECLAIM_ACCOUNT| - SLAB_MEM_SPREAD|SLAB_ACCOUNT), - init_once); + ext4_inode_cachep = kmem_cache_create_usercopy("ext4_inode_cache", + sizeof(struct ext4_inode_info), 0, + (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD| + SLAB_ACCOUNT), + offsetof(struct ext4_inode_info, i_data), + sizeof_field(struct ext4_inode_info, i_data), + init_once); if (ext4_inode_cachep == NULL) return -ENOMEM; return 0;