From patchwork Mon Aug 28 21:34:52 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9926283 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 8F5BE603B5 for ; Mon, 28 Aug 2017 21:38:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 83E33287D7 for ; Mon, 28 Aug 2017 21:38:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 78F7F287EE; Mon, 28 Aug 2017 21:38:58 +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 2B2FF287D7 for ; Mon, 28 Aug 2017 21:38:56 +0000 (UTC) Received: (qmail 13514 invoked by uid 550); 28 Aug 2017 21:35:45 -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 12199 invoked from network); 28 Aug 2017 21:35:37 -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=2ejy2ZaewEVWrIC2ft1+HA6IEafJqiE+Y65Qzj0gFlQ=; b=IfXgHvY0StA1AHiDX/iPCSTDmnue3lfy5NTiZvBiNUAhv0MhxqWoXNVVPjWJVx3Lxd Rjp+d4B1Ng2AmQROSahX7N1N3bqe5uHSUAOa7me+FHOua/fMgqbi+ub6wdq8nyWVd5xY DplSueqpXyFCIdKJZMGEg513T5ZfIucw73gHg= 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=2ejy2ZaewEVWrIC2ft1+HA6IEafJqiE+Y65Qzj0gFlQ=; b=VqxqF8X16ohOm0ltAJSS853VLW00yTM6qELO7V2qxiMkAuWHbkeuQ4BEtYQRKO0WA0 cwgrL0ifuuD87osDFZ72ujV6ff95yv7hRdBdjIXa7nonGO0IfUakbt+IM9+6NnTsXNfT V5yGfX8vZS2H3yCsKGL6PF31ZQv5CnyCok8hAdRfcxRb+/SRY4NnvM1AgHD3nL8AfXQ5 huGgUZMK8DsXWXJiuFBB7sVIuj42ysyJGoPAc9wL8pGgnXnoN4rqFvx0akvuFefRBtoQ h4cks9NaalkoF+q1qj5+pFZ78OH9ea9XoCrmssc1dfDsv2ITHU4TRbZjnKKw4of5sOfM ZTmw== X-Gm-Message-State: AHYfb5h9vvW3jAXsGkXj+z6n6ZansKqL9V9cVJF/FPq6Fy3ixk32/u07 T2ld5Jyzw4ZoIDvk X-Received: by 10.98.215.1 with SMTP id b1mr1835915pfh.213.1503956125526; Mon, 28 Aug 2017 14:35:25 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , Boaz Harrosh , linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Mon, 28 Aug 2017 14:34:52 -0700 Message-Id: <1503956111-36652-12-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 11/30] exofs: Define usercopy region in exofs_inode_cache slab cache X-Virus-Scanned: ClamAV using ClamSMTP From: David Windsor The exofs short symlink names, stored in struct exofs_i_info.i_data and therefore contained in the exofs_inode_cache slab cache, need to be copied to/from userspace. cache object allocation: fs/exofs/super.c: exofs_alloc_inode(...): ... oi = kmem_cache_alloc(exofs_inode_cachep, GFP_KERNEL); ... return &oi->vfs_inode; fs/exofs/namei.c: exofs_symlink(...): ... inode->i_link = (char *)oi->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 in 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 exofs_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: Boaz Harrosh Signed-off-by: Kees Cook --- fs/exofs/super.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/exofs/super.c b/fs/exofs/super.c index 819624cfc8da..e5c532875bb7 100644 --- a/fs/exofs/super.c +++ b/fs/exofs/super.c @@ -192,10 +192,13 @@ static void exofs_init_once(void *foo) */ static int init_inodecache(void) { - exofs_inode_cachep = kmem_cache_create("exofs_inode_cache", + exofs_inode_cachep = kmem_cache_create_usercopy("exofs_inode_cache", sizeof(struct exofs_i_info), 0, SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD | - SLAB_ACCOUNT, exofs_init_once); + SLAB_ACCOUNT, + offsetof(struct exofs_i_info, i_data), + sizeof_field(struct exofs_i_info, i_data), + exofs_init_once); if (exofs_inode_cachep == NULL) return -ENOMEM; return 0;