From patchwork Thu Jan 11 02:02:46 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 10156515 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 0B27B605BA for ; Thu, 11 Jan 2018 02:07:26 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EE7DD2870F for ; Thu, 11 Jan 2018 02:07:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E244528711; Thu, 11 Jan 2018 02:07:25 +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 DAFBF2870F for ; Thu, 11 Jan 2018 02:07:24 +0000 (UTC) Received: (qmail 30594 invoked by uid 550); 11 Jan 2018 02:04:00 -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 30190 invoked from network); 11 Jan 2018 02:03:46 -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=FM2z8PafjAhA/L9sC5HMtqa2By/d9zrtd457W6KsFwM=; b=UMwWONpqglw0YZCtcv7/p2U9FRtxVPfhNxVWQLO8YzrhYeWfZIGsQ0G5m8UPIN432A k+LILUq9KSV7QdSHhuNft54z957AwRU9GRGWsd/e25b7O3wB9tzkZKoCay9c0eyd8Z0U C7OVhvb/+ZqLg6/fe6dDCbgD1klCY2SYR09CQ= 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=FM2z8PafjAhA/L9sC5HMtqa2By/d9zrtd457W6KsFwM=; b=sVHChSIBBUfF7Vgx63iW5Bodmos5d6eYff5y8IE1qrOEq4KAqYG6WGEa30b2AW/hyD X8DOnnu4sPwIEI4IYF3fhvSyXXy0GXxFjAu5IZ4Acenpf97SWIZnQTvGZVKP+nzOgICP sR6PIwYF2FqYX8rTb7WMtApuQySZV/ESJtmhsqAw9IN/SallqWFla6h0l9FQB9Cfjv34 4l5VZgOTdDqh8O4HOoA06noeuiBK+or43N0oPOJTG2iP1zjbRNImAAXOmfnWpU/+s2vP nodZ7IShBqxU9REQ2r4IPYdSoRJUUBA696tiqpF/WuQPAtKolxjzCzZs0HhRo4OUUAeA 767A== X-Gm-Message-State: AKGB3mKjVz/yFRb36ucBwTzO0ZvXXVdXsbJbG7csTxKj7791R8G198lM 8cCULoc+8isVw8gH1/WGM/wFLA== X-Google-Smtp-Source: ACJfBoubyricT1okZ/+Aelzsl2rrs7gVeuncHINb9kdGScrDwY1gL3I0FCEbmxvHxMebHW5a5Sk4eg== X-Received: by 10.84.216.69 with SMTP id f5mr16807355plj.422.1515636214465; Wed, 10 Jan 2018 18:03:34 -0800 (PST) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , Jan Kara , linux-ext4@vger.kernel.org, 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 , Luis de Bethencourt , 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: Wed, 10 Jan 2018 18:02:46 -0800 Message-Id: <1515636190-24061-15-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1515636190-24061-1-git-send-email-keescook@chromium.org> References: <1515636190-24061-1-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] [PATCH 14/38] ext2: Define usercopy region in ext2_inode_cache slab cache X-Virus-Scanned: ClamAV using ClamSMTP From: David Windsor The ext2 symlink pathnames, stored in struct ext2_inode_info.i_data and therefore contained in the ext2_inode_cache slab cache, need to be copied to/from userspace. cache object allocation: fs/ext2/super.c: ext2_alloc_inode(...): struct ext2_inode_info *ei; ... ei = kmem_cache_alloc(ext2_inode_cachep, GFP_NOFS); ... return &ei->vfs_inode; fs/ext2/ext2.h: EXT2_I(struct inode *inode): return container_of(inode, struct ext2_inode_info, vfs_inode); fs/ext2/namei.c: ext2_symlink(...): ... inode->i_link = (char *)&EXT2_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 ext2_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: Jan Kara Cc: linux-ext4@vger.kernel.org Signed-off-by: Kees Cook Acked-by: Jan Kara --- fs/ext2/super.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/ext2/super.c b/fs/ext2/super.c index 7646818ab266..50b8946c3d1a 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -220,11 +220,13 @@ static void init_once(void *foo) static int __init init_inodecache(void) { - ext2_inode_cachep = kmem_cache_create("ext2_inode_cache", - sizeof(struct ext2_inode_info), - 0, (SLAB_RECLAIM_ACCOUNT| - SLAB_MEM_SPREAD|SLAB_ACCOUNT), - init_once); + ext2_inode_cachep = kmem_cache_create_usercopy("ext2_inode_cache", + sizeof(struct ext2_inode_info), 0, + (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD| + SLAB_ACCOUNT), + offsetof(struct ext2_inode_info, i_data), + sizeof_field(struct ext2_inode_info, i_data), + init_once); if (ext2_inode_cachep == NULL) return -ENOMEM; return 0;