From patchwork Wed Sep 20 20:45:20 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9962447 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 715B860208 for ; Wed, 20 Sep 2017 20:48:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 64F7929226 for ; Wed, 20 Sep 2017 20:48:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5A06629229; Wed, 20 Sep 2017 20:48:29 +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 5E39A29226 for ; Wed, 20 Sep 2017 20:48:28 +0000 (UTC) Received: (qmail 4057 invoked by uid 550); 20 Sep 2017 20:46:32 -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 3724 invoked from network); 20 Sep 2017 20:46:24 -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=DaDd4yc4IlPMUJsl+NYmyankzTRdIIRePDn0+bmi6SI=; b=EIV44FSh0JNMu0OSL4SSmhdIAdzrg6tBPPOSx9szrlxeyYOuezsIvPLpV/PDQRyXla Z9mUc0NQZva8X3aFzj8K2NYaj9tBWL3f9nDwk1Y9CUZMd+KKc1QnUy/PuYsH9upJUjF4 1mXfSG7z+9uysVqb885v9sW4sFLW9lCwt0mHg= 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=DaDd4yc4IlPMUJsl+NYmyankzTRdIIRePDn0+bmi6SI=; b=HT53rMJHDBnj+lfpqDyLqULFf2D18ijRT/EIRThGYemtRh2W2U8pd6xoFDmlsebl77 KgFRbessxOog5r+RfOwWXg7NMrAGhRzm13V6AKHQIRQSXzl90jp0KB5spcwJAm+LN9C9 Bol8S4prp/eNx1VEyHtj+u5ONnOGJBSsjNEJbqY4RP3xl6J93E3Elc0uFbOGWzwWlr1s WfbJeAs3HeCSSbN/N8GTa2YGIzSKkQ0J5vU6fSVZdZePaVn2EFiYK3hIaRJHQpR81vRq gQcD0cpb+HGORqmR66GvAkZmhqXgyCayfHgFE6wtD2BP38GyYulnPerNSA8+O/oz2lnF IGfg== X-Gm-Message-State: AHPjjUhRO6pReNea19WWwjNTWOuOvXUn8xq8I/h5OSgQy0TKUtlQOzYt vidy39PzcNGxkKnmzXhzLoEoww== X-Google-Smtp-Source: AOwi7QBudTs6+9IokAgC0t94vW1UuTut8UTpOKHtxDrxTNGgs9P862/RfSJ9M5Sf09tj7XhRwV69ug== X-Received: by 10.98.100.206 with SMTP id y197mr3424359pfb.53.1505940372688; Wed, 20 Sep 2017 13:46:12 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , Christoph Hellwig , linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Wed, 20 Sep 2017 13:45:20 -0700 Message-Id: <1505940337-79069-15-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 14/31] vxfs: Define usercopy region in vxfs_inode slab cache X-Virus-Scanned: ClamAV using ClamSMTP From: David Windsor vxfs symlink pathnames, stored in struct vxfs_inode_info field vii_immed.vi_immed and therefore contained in the vxfs_inode slab cache, need to be copied to/from userspace. cache object allocation: fs/freevxfs/vxfs_super.c: vxfs_alloc_inode(...): ... vi = kmem_cache_alloc(vxfs_inode_cachep, GFP_KERNEL); ... return &vi->vfs_inode; fs/freevxfs/vxfs_inode.c: cxfs_iget(...): ... inode->i_link = vip->vii_immed.vi_immed; 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 vxfs_inode 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: Christoph Hellwig Signed-off-by: Kees Cook --- fs/freevxfs/vxfs_super.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/freevxfs/vxfs_super.c b/fs/freevxfs/vxfs_super.c index 455ce5b77e9b..c143e18d5a65 100644 --- a/fs/freevxfs/vxfs_super.c +++ b/fs/freevxfs/vxfs_super.c @@ -332,9 +332,13 @@ vxfs_init(void) { int rv; - vxfs_inode_cachep = kmem_cache_create("vxfs_inode", + vxfs_inode_cachep = kmem_cache_create_usercopy("vxfs_inode", sizeof(struct vxfs_inode_info), 0, - SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL); + SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, + offsetof(struct vxfs_inode_info, vii_immed.vi_immed), + sizeof_field(struct vxfs_inode_info, + vii_immed.vi_immed), + NULL); if (!vxfs_inode_cachep) return -ENOMEM; rv = register_filesystem(&vxfs_fs_type);