From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F336DC2BA80 for ; Mon, 6 Apr 2020 12:03:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CAAB02078A for ; Mon, 6 Apr 2020 12:03:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="TrNZMNsp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727960AbgDFMDg (ORCPT ); Mon, 6 Apr 2020 08:03:36 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:45100 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727909AbgDFMDf (ORCPT ); Mon, 6 Apr 2020 08:03:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=PV8JJxEiLr08d7AGp8vNVfJqXdm678ymZF9p2kLqXew=; b=TrNZMNspY0PX1BOvuJelHbbkXY lhyqo5jZSiRg9/Qg5pN2W/mYCBH14sBVPcDHJuelwhAhkkry2M0TD1bXF9znhj+xADGq6xNgt8XIk Gb65j+D8qGt0Q4l+0Y3B6Lht59ahpbj5FSTdVjXbzhzIIxoaztU17I7x04MkSKMmKMxTmDeMhAqpY ERvbLh5kny23f3mMIHhj1zvENJ77NmORIyymEpX+6/oGu0w72XSMCvd84JO/GI0VL0wyS9yhvFzvB kQB+sRGsEXeDpyAPRK7kNyIlkd3myqCQRUl2RepqggixrnIGN7DPfe71Ix4g0AHAqnKZ8Kf/5oPTq wskuh5/A==; Received: from [2001:4bb8:180:5765:7ca0:239a:fe26:fec2] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jLQTQ-0003Pu-Ui; Mon, 06 Apr 2020 12:03:29 +0000 From: Christoph Hellwig To: Andrew Morton , Alexander Viro Cc: Jeremy Kerr , Arnd Bergmann , linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 6/6] exec: open code copy_string_kernel Date: Mon, 6 Apr 2020 14:03:12 +0200 Message-Id: <20200406120312.1150405-7-hch@lst.de> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200406120312.1150405-1-hch@lst.de> References: <20200406120312.1150405-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently copy_string_kernel is just a wrapper around copy_strings that simplifies the calling conventions and uses set_fs to allow passing a kernel pointer. But due to the fact the we only need to handle a single kernel argument pointer, the logic can be sigificantly simplified while getting rid of the set_fs. Signed-off-by: Christoph Hellwig --- fs/exec.c | 43 ++++++++++++++++++++++++++++++++++--------- 1 file changed, 34 insertions(+), 9 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index b2a77d5acede..7c64cae8ad0a 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -592,17 +592,42 @@ static int copy_strings(int argc, struct user_arg_ptr argv, */ int copy_string_kernel(const char *arg, struct linux_binprm *bprm) { - int r; - mm_segment_t oldfs = get_fs(); - struct user_arg_ptr argv = { - .ptr.native = (const char __user *const __user *)&arg, - }; + int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating null */; + unsigned long pos = bprm->p; + + if (len == 0) + return -EFAULT; + if (!valid_arg_len(bprm, len)) + return -E2BIG; + + /* We're going to work our way backwords. */ + arg += len; + bprm->p -= len; + if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin) + return -E2BIG; + + while (len > 0) { + unsigned int bytes_to_copy = min_t(unsigned int, len, + min_not_zero(offset_in_page(pos), PAGE_SIZE)); + struct page *page; + char *kaddr; - set_fs(KERNEL_DS); - r = copy_strings(1, argv, bprm); - set_fs(oldfs); + pos -= bytes_to_copy; + arg -= bytes_to_copy; + len -= bytes_to_copy; - return r; + page = get_arg_page(bprm, pos, 1); + if (!page) + return -E2BIG; + kaddr = kmap_atomic(page); + flush_arg_page(bprm, pos & PAGE_MASK, page); + memcpy(kaddr + offset_in_page(pos), arg, bytes_to_copy); + flush_kernel_dcache_page(page); + kunmap_atomic(kaddr); + put_arg_page(page); + } + + return 0; } EXPORT_SYMBOL(copy_string_kernel); -- 2.25.1