From patchwork Mon Aug 28 21:34:51 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9926263 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 4C37B603B5 for ; Mon, 28 Aug 2017 21:37:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3DAB6287D4 for ; Mon, 28 Aug 2017 21:37:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 32993287E0; Mon, 28 Aug 2017 21:37:56 +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 E93E6287D4 for ; Mon, 28 Aug 2017 21:37:54 +0000 (UTC) Received: (qmail 13312 invoked by uid 550); 28 Aug 2017 21:35:40 -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 12149 invoked from network); 28 Aug 2017 21:35:36 -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=qNE9ms8moFnXLEr88yZvhN/TGQtWSxq8Ws5IuT6ynhg=; b=Yq14x+fXLrHomGi3VwRIMyNvVegyoX8Re3JBm4mscxN8NO9llgvz6wbKsyqTu0rbFI szmsqBFZDgkMFxSGAqO8i1Hip6vWnfbI1bvOvGzbHWRfoiEQrnZZ0UyG6JuyyqA8DHwF M0DksWYR/xlx//muGkN5tnwOZLXz3txCP72u4= 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=qNE9ms8moFnXLEr88yZvhN/TGQtWSxq8Ws5IuT6ynhg=; b=GHCYiiq5Y3pcsQp6CI695KQTI2BsxNNML2n9guaQrIPHc69lxlm3n7qF4F/5jwDIfa 4THX86K2q5l48z7DNUHzzgKVBF7Rsl/4F6AI4ku31XMuUAZbxReWj7gRHx2HtGtUlNHV h8HdbnKC8CKBtmphSTCXKOh71fnY/U1/5j7vUVJESN/MGcPbn84aMsArO0xjMKn/Cchr 4+3TasO2LS1ewAIcLGgIzLILQNhAKzS82Mi9X0X0jTF3JSYdlqwC71wcpMlxmnA7Oxtf 39hXLNCrR9JR3ABxv8/PB8gRIx/TA9RVY5TC4l00X6FRYTa3Mo0jEthca4YnotXwFoGJ aBEA== X-Gm-Message-State: AHYfb5hC8DRE4omNvIxtqnpdJajP7+E4Q38n+wf0GydOATwBa6LwdmA9 K5Sb6DROdAp9X6TW X-Received: by 10.84.216.28 with SMTP id m28mr2309035pli.305.1503956124314; Mon, 28 Aug 2017 14:35:24 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , Luis de Bethencourt , Salah Triki , linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Mon, 28 Aug 2017 14:34:51 -0700 Message-Id: <1503956111-36652-11-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 10/30] 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 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 4a4a5a366158..1c2dcbee79dd 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;