From patchwork Thu Jan 11 02:02:45 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 10156517 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 54690605BA for ; Thu, 11 Jan 2018 02:07:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 43ED32870F for ; Thu, 11 Jan 2018 02:07:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 37D7528711; Thu, 11 Jan 2018 02:07:40 +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 151A62870F for ; Thu, 11 Jan 2018 02:07:38 +0000 (UTC) Received: (qmail 30562 invoked by uid 550); 11 Jan 2018 02:03:59 -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 30147 invoked from network); 11 Jan 2018 02:03:45 -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=2oFLI4X1ilmxemH/4XjXppVnrV7fjSHhztuC+ulSYuk=; b=eLaJZmFRIhXinVra7VpwasNsieo9Y+V/9N0gkfybll/+fPC4pU19jgvCTFyr/x1TdQ hhD/FIXgVuuCIKiQV8CvNpFyy/34urWBgbKCtuaWksCdLc+2loVjyI5/JDFY9Etk29jp zfSk2RVITLnPxMedNh1Q01/wPDEm//n1HHmoA= 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=2oFLI4X1ilmxemH/4XjXppVnrV7fjSHhztuC+ulSYuk=; b=OrSlCAr9t1amIG6cAilfDPPTVWEUYrkNcdrgpYwbfQRSLiVjet+tVGBzdI/iMf663m 9WaiebyIao3rLQmZKTSnFbMirCx2iNzn2hl2Upa4HS2cRABbrngtZhz0gPuvdYOfsxGj 736zHo6jZ7VLtwRksL+YmWCisEZkPR+W1UtJpswGF8WYmd2JYuyWRfJCPoPTCaHOzrXw BFSHafBLKfVygOXMyoAy4fWiSR6xemyI6y22lmU+kLgM3Qn7N972k7rAIjkb+7aTORNn wddt1kxcAgfaEjX3JPs/MmTCLajPFFv6o9dQ4GV749W6AQAuXNp7plviR5VH/N+0vcCV HuQQ== X-Gm-Message-State: AKGB3mJIbamrz63jZaoY+63MlOQcs9DZNAFlvEN+C+C3p/TfeCOOB3F5 SGLO5Ai2+nZEjqyt5DA2ZbZ5UiVK8e0= X-Google-Smtp-Source: ACJfBoslQJwPsYlujsJPZYI5/0vvUxCmU/80Ji7Nq+1bflq66eeW/jIXfqp7dFbfWDXz2vQTVO4oew== X-Received: by 10.98.3.1 with SMTP id 1mr18457492pfd.165.1515636213539; Wed, 10 Jan 2018 18:03:33 -0800 (PST) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , "Theodore Ts'o" , Andreas Dilger , 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 18:02:45 -0800 Message-Id: <1515636190-24061-14-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 13/38] 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 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: "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 7c46693a14d7..57a8fa451d3e 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1036,11 +1036,13 @@ 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;