From patchwork Tue Jan 9 20:55:42 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 10153337 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 1FCA2602CA for ; Tue, 9 Jan 2018 20:59:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 15DA92040D for ; Tue, 9 Jan 2018 20:59:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0A47E204C4; Tue, 9 Jan 2018 20:59:27 +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 D7EE42040D for ; Tue, 9 Jan 2018 20:59:25 +0000 (UTC) Received: (qmail 8074 invoked by uid 550); 9 Jan 2018 20:57:16 -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 7928 invoked from network); 9 Jan 2018 20:57:13 -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=YKnoLn5y8s2UpHwNQGuC3A7deJajJSC7iR0HkqVn8JQ=; b=EeBEUHqv4VeIBg+B1j+7uGX34f/J7b1Fg7SNZ1dVbcVQxXAXB2bq4q7reiLfbUhXja ukOn+QkBYDG/pEDnxECXHyrnp2bR0ELRRGCOwR+6o2Tvls34e8NZd9Ra6dmphBMIhQOl rdKHQR28QKWBz3jfBTg5rZzoA1FoN/X9URnoE= 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=YKnoLn5y8s2UpHwNQGuC3A7deJajJSC7iR0HkqVn8JQ=; b=OjfbHwSJu/NgbherU7U+g/NN4qp5N7kqpjNCvOYx2iBu0smQoZ0KOvXzBQ8YeFYtBv GGh8KFxMmsKsko5o5AnLIW39VsCs5qCvLYEN5xMskpuuFJGlLUgP/aAc41UVv6eEKRvr +nEckGiRsFX2CyUCbm/U+i6YVeXeVsvFzCEo0yqwnhuTaKcuH+zqW4CsbZxfuJu4ruzk mCw85M4L7kvWluYxOTIGlF9J+1XbTJErSEYdyFYFOSElAYzzQb2NnIqM8EBSyuZ4hkuM GtZvqMt3gt+AONXEim/n55jHEZ4NsT6+XxcdJv3Zp4yzeTKaOLxzU/LEK1HKa2eFCgeW AUPA== X-Gm-Message-State: AKwxytdPMk5qaYpl5O+to04e0HCi8788+wSD5mdcu2XeJuTWGXNDU3X6 /oSjt27DNQmhUaLfw4vrUNAngw== X-Google-Smtp-Source: ACJfBov+31QH9oIQB4uANEMtO6GY5Uw0llm+vNMT0f79XQZpEAsuBWN4cIt2YToCwEROFVyHRE6P7Q== X-Received: by 10.98.89.26 with SMTP id n26mr1062428pfb.160.1515531421924; Tue, 09 Jan 2018 12:57:01 -0800 (PST) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , Luis de Bethencourt , Salah Triki , Linus Torvalds , Alexander Viro , Andrew Morton , Andy Lutomirski , Christoph Hellwig , Christoph Lameter , "David S. Miller" , Laura Abbott , Mark Rutland , "Martin K. Petersen" , Paolo Bonzini , Christian Borntraeger , Christoffer Dall , Dave Kleikamp , Jan Kara , Marc Zyngier , Rik van Riel , Matthew Garrett , linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Tue, 9 Jan 2018 12:55:42 -0800 Message-Id: <1515531365-37423-14-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1515531365-37423-1-git-send-email-keescook@chromium.org> References: <1515531365-37423-1-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] [PATCH 13/36] befs: Define usercopy region in befs_inode_cache slab cache X-Virus-Scanned: ClamAV using ClamSMTP From: David Windsor befs symlink pathnames, stored in struct befs_inode_info.i_data.symlink and therefore contained in the befs_inode_cache slab cache, need to be copied to/from userspace. cache object allocation: fs/befs/linuxvfs.c: befs_alloc_inode(...): ... bi = kmem_cache_alloc(befs_inode_cachep, GFP_KERNEL); ... return &bi->vfs_inode; befs_iget(...): ... strlcpy(befs_ino->i_data.symlink, raw_inode->data.symlink, BEFS_SYMLINK_LEN); ... inode->i_link = befs_ino->i_data.symlink; 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 befs_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 dynamically sized 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: Luis de Bethencourt Cc: Salah Triki Signed-off-by: Kees Cook Acked-by: Luis de Bethencourt --- fs/befs/linuxvfs.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/fs/befs/linuxvfs.c b/fs/befs/linuxvfs.c index ee236231cafa..af2832aaeec5 100644 --- a/fs/befs/linuxvfs.c +++ b/fs/befs/linuxvfs.c @@ -444,11 +444,15 @@ static struct inode *befs_iget(struct super_block *sb, unsigned long ino) static int __init befs_init_inodecache(void) { - befs_inode_cachep = kmem_cache_create("befs_inode_cache", - sizeof (struct befs_inode_info), - 0, (SLAB_RECLAIM_ACCOUNT| - SLAB_MEM_SPREAD|SLAB_ACCOUNT), - init_once); + befs_inode_cachep = kmem_cache_create_usercopy("befs_inode_cache", + sizeof(struct befs_inode_info), 0, + (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD| + SLAB_ACCOUNT), + offsetof(struct befs_inode_info, + i_data.symlink), + sizeof_field(struct befs_inode_info, + i_data.symlink), + init_once); if (befs_inode_cachep == NULL) return -ENOMEM;