From patchwork Wed Sep 20 20:45:17 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9962465 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 F019E60208 for ; Wed, 20 Sep 2017 20:49:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E34B729229 for ; Wed, 20 Sep 2017 20:49:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D66972922C; Wed, 20 Sep 2017 20:49:25 +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 BEDA429229 for ; Wed, 20 Sep 2017 20:49:24 +0000 (UTC) Received: (qmail 5168 invoked by uid 550); 20 Sep 2017 20:46:34 -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 3639 invoked from network); 20 Sep 2017 20:46:22 -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=W8b6GrVTlp0QMiGb2fXzSBN6u0+CWy8UjPIajv/FL/1u4Ox4l8nJ4zM7fpx7JJl3YY H84vOPqsAuFKJZeagUHxifIAkJL9sUqGOWm9nt8UmIuI5MZG2uzkVZQDvrFFsWt2wxav gA0fNDeEi+RgChBu5+8WBZeKeGZQnZ6cDuOtY= 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=FAkLBeGGI+k0Uhs/tH3sodHaENltH+F8iSvfcOwbuuPwvKYXnvwpmnzxhXfMoMDTBD xzikwFTg6K0a21YM/6keELxUBX5kYycZzRjl+E4pv/bNYhwJptzIJwzExCzBegRtq6as oZQSlo0DpI1MYbtVjjMeBN7+XObdNE40ZgBpViXNk9GwnhO5oJcA9d1k+bAuc4Lt2Jkn lf76O/NzJ/6269rNiFgjdGm5sTs6Dh3Fbagyx0zD7QRDFK4oIvSaw/B2e+3nNo+08S5F yBE5/y6PBzg8bwAgEXAeguzfouMnCNhuQDqx7uFCkbeh3XIr7xqzCUN2GN3hUaQhcPU2 v6GQ== X-Gm-Message-State: AHPjjUhxjDsY4wcHibYHma0CpM8e7gmFP2XRq5VfllHs9orVsJ/Lr4Nz RyzTlM64S2XGrWYiA3BnDgmvZg== X-Google-Smtp-Source: AOwi7QB5R+I8CTm74widO7UyglY9ao0h0tZkBIeeanyhzeYoWJE99yEbcQ/OCVYSwlknIxV/7suFWA== X-Received: by 10.84.150.130 with SMTP id h2mr2966393plh.436.1505940370584; Wed, 20 Sep 2017 13:46:10 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , Boaz Harrosh , linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Wed, 20 Sep 2017 13:45:17 -0700 Message-Id: <1505940337-79069-12-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 11/31] 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;