From patchwork Mon Aug 28 21:34:48 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9926269 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 3B4DD60383 for ; Mon, 28 Aug 2017 21:37:57 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 300D7287D4 for ; Mon, 28 Aug 2017 21:37:57 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2451C287DA; Mon, 28 Aug 2017 21:37:57 +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 EEB94287E8 for ; Mon, 28 Aug 2017 21:37:54 +0000 (UTC) Received: (qmail 12219 invoked by uid 550); 28 Aug 2017 21:35:38 -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 11930 invoked from network); 28 Aug 2017 21:35:33 -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=GwIrOyNMM43PFCitRpZ60qqOK3YH+Fds+Kgy/vS6VOY=; b=f4+KzIILDPsYJ5MFyqO/BQ3bEzybNX5HA7P5QGReuBJqlZiVAFrrhOjWpxeY5kSMbS QCjHkDRZ8+fZGvAwv5zg8L7AAboQRTGAxpEUC1VF2lK6fix6Ml0xeDJ/AHjLB7+IYBea t0q7oAqDpGcBefqsD46dsJkyW4j6IKt8UAg6I= 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=GwIrOyNMM43PFCitRpZ60qqOK3YH+Fds+Kgy/vS6VOY=; b=oUAiT6H8aQwiiuycmVTM7fxf1P37fs2FAQjQyR7BWEkVr09Yy+47lVDnb6xuEzgBd9 iP+n+Mb/Pmwiac827WpsV3Ivez2DstqiZkU7BHfKeemffJwkRH9wMSFer8xujNZalPel jwndZBB1AICPNq8q+EyqciTG0EqAgXvZlMixOgTHV0dpefiAQvxu/BVdx1hSOJlEP/fJ SGTJUgdXz5iN5G7fMveQR/8HXrNGxXr/T+0lK7MEO7kQ3UbGej8xKvJehDPVVqKu3597 Qm8zNhxMvT0/w3dNzTDsYavVlh6c9alnLZdvGQWlgTY6Sy2isPr3066FbGDLtxGfGq4s 2cOw== X-Gm-Message-State: AHYfb5hqBc+NxV0W7PCOe3jRgTm0kMEVlbsMpvQ3dvFccOxDpgc9TJKd ds46KBOqIo5V/QM0 X-Received: by 10.84.210.228 with SMTP id a91mr2362526pli.66.1503956122031; Mon, 28 Aug 2017 14:35:22 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , "Theodore Ts'o" , Andreas Dilger , linux-ext4@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Mon, 28 Aug 2017 14:34:48 -0700 Message-Id: <1503956111-36652-8-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 07/30] ext4: Define usercopy region in ext4_inode_cache slab cache X-Virus-Scanned: ClamAV using ClamSMTP From: David Windsor The ext4 symlink pathnames, stored in struct ext4_inode_info.i_data and therefore contained in the ext4_inode_cache slab cache, need to be copied to/from userspace. cache object allocation: fs/ext4/super.c: ext4_alloc_inode(...): struct ext4_inode_info *ei; ... ei = kmem_cache_alloc(ext4_inode_cachep, GFP_NOFS); ... return &ei->vfs_inode; include/trace/events/ext4.h: #define EXT4_I(inode) \ (container_of(inode, struct ext4_inode_info, vfs_inode)) fs/ext4/namei.c: ext4_symlink(...): ... inode->i_link = (char *)&EXT4_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 ext4_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: "Theodore Ts'o" Cc: Andreas Dilger Cc: linux-ext4@vger.kernel.org Signed-off-by: Kees Cook --- fs/ext4/super.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 0886fe82e9c4..79c3b1b11364 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1038,11 +1038,13 @@ static void init_once(void *foo) static int __init init_inodecache(void) { - ext4_inode_cachep = kmem_cache_create("ext4_inode_cache", - sizeof(struct ext4_inode_info), - 0, (SLAB_RECLAIM_ACCOUNT| - SLAB_MEM_SPREAD|SLAB_ACCOUNT), - init_once); + ext4_inode_cachep = kmem_cache_create_usercopy("ext4_inode_cache", + sizeof(struct ext4_inode_info), 0, + (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD| + SLAB_ACCOUNT), + offsetof(struct ext4_inode_info, i_data), + sizeof_field(struct ext4_inode_info, i_data), + init_once); if (ext4_inode_cachep == NULL) return -ENOMEM; return 0;