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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DB049C77B7C for ; Wed, 10 May 2023 01:24:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234829AbjEJBYm (ORCPT ); Tue, 9 May 2023 21:24:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52250 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229673AbjEJBYk (ORCPT ); Tue, 9 May 2023 21:24:40 -0400 Received: from mail-pg1-x529.google.com (mail-pg1-x529.google.com [IPv6:2607:f8b0:4864:20::529]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8A90E52 for ; Tue, 9 May 2023 18:24:39 -0700 (PDT) Received: by mail-pg1-x529.google.com with SMTP id 41be03b00d2f7-52160f75920so4449884a12.2 for ; Tue, 09 May 2023 18:24:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1683681879; x=1686273879; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=igRRy0hX7f/8CQM1lxoKnRs6kwwNUxJvg8cGqw0HOuQ=; b=k1O+dADODFwAhrz4JbRuNYY+8NScyFBnJzcuqM1iWQ4IUs7H2EPDSAafNUd49nYt9X ORpfIMbhkA+ODuZoNhsJTMc8FjkeFDteswksik9ouMLRPd0Mw/2IIL8SuIRgNKHZOd3q iVEdBjcLKkLtrXTZFLmY+he37DpGG1gOSkZW0OrUe7n/hDPI0Mt5bwPTO8WWsCZ4xvtn zmmcuCRpDufO+Y+yy3NmdvThiyrnIvCqEAAzERKWMYqDS5yRQ2bvxtQQjCUPcKQjpwrf DDCcdyZyEsWzxu11yCiD+2W4U6Pie2VUbtpxw/sMOL7AAdWF694/56gGj35JRGUCg9/T PDJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1683681879; x=1686273879; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=igRRy0hX7f/8CQM1lxoKnRs6kwwNUxJvg8cGqw0HOuQ=; b=FZBTFT+NqlUgEjI8uYRhyVMj4rd6tJE52eHCsnySfdVdkXpupiI9Wl6oN4EoydTlVw idcmabXVRyoq5FxlONDaozquCGpVGXpOVxWlBGjhbw2JZOtCyVCUBUA6BA4XNhMFPoqy SQ8yMfEKIhsgozl6y3KOcM1F/joQ53qKBKWWUPySNpYnnckiGYVBl+yYLj9Bl3/VwYPY /p1DlFGdMqUnd3IDH3yeyVMgNyS+THq7ECHUqChbvhq6719G4DJJHpEbh0hnrIJLFiA1 UxWjX7AgHkI5n8kc3rJmbbvmI0nZ11QqlkTgNDr6Xe5yVJ9ZWrZAEnpnKv3FSIXubQKV 34rw== X-Gm-Message-State: AC+VfDyH9Y8ixeONvYi+Q65tzFTEY1lMoUfX4alH9ZyqH5Z3GtFCeVsF 8Jcb2FFgD7dviREX4HM6lbA= X-Google-Smtp-Source: ACHHUZ6GTXyHapDnbueeMr+/heuvgq8+sYS6+2PYxm+oa36EdoJBtzUt+Ba2VWcrodtlqLOJkXTHKA== X-Received: by 2002:a17:903:2347:b0:1a9:91d7:ba2 with SMTP id c7-20020a170903234700b001a991d70ba2mr19855801plh.48.1683681878925; Tue, 09 May 2023 18:24:38 -0700 (PDT) Received: from localhost (2603-800c-1a02-1bae-a7fa-157f-969a-4cde.res6.spectrum.com. [2603:800c:1a02:1bae:a7fa:157f:969a:4cde]) by smtp.gmail.com with ESMTPSA id s8-20020a170902a50800b001ac8e0ea157sm2298979plq.144.2023.05.09.18.24.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 May 2023 18:24:38 -0700 (PDT) Sender: Tejun Heo Date: Tue, 9 May 2023 15:24:37 -1000 From: Tejun Heo To: Azeem Shaikh Cc: Greg Kroah-Hartman , security@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] kernfs: Prefer strscpy over strlcpy calls Message-ID: References: <20230510011122.3040915-1-azeemshaikh38@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230510011122.3040915-1-azeemshaikh38@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 10, 2023 at 01:11:22AM +0000, Azeem Shaikh wrote: ... > +/* strscpy_mock_strlcpy - imitates strlcpy API but uses strscpy underneath. */ > +static size_t strscpy_mock_strlcpy(char *dest, const char *src, size_t count) > +{ > + strscpy(dest, src, count); > + return strlen(src); > +} I'm not sure this is a meaningful conversion. One benefit of strscpy() is that it's less error-prone to check for overflows. What's the point of removing strlcpy() if we end up sprinkling lesser duplicates in the tree? > static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) > { > if (!kn) > - return strlcpy(buf, "(null)", buflen); > + return strscpy_mock_strlcpy(buf, "(null)", buflen); > > - return strlcpy(buf, kn->parent ? kn->name : "/", buflen); > + return strscpy_mock_strlcpy(buf, kn->parent ? kn->name : "/", buflen); > } Can you follow the users and convert the users accordingly rather than masking it from here? ie. make kernfs_name() and friends return -E2BIG when source is too long like strscpy(). I don't think anybody cares, actually. > /* kernfs_node_depth - compute depth from @from to @to */ > @@ -141,13 +148,13 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, > int i, j; > > if (!kn_to) > - return strlcpy(buf, "(null)", buflen); > + return strscpy_mock_strlcpy(buf, "(null)", buflen); > > if (!kn_from) > kn_from = kernfs_root(kn_to)->kn; > > if (kn_from == kn_to) > - return strlcpy(buf, "/", buflen); > + return strscpy_mock_strlcpy(buf, "/", buflen); > > common = kernfs_common_ancestor(kn_from, kn_to); > if (WARN_ON(!common)) > @@ -159,16 +166,16 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, > buf[0] = '\0'; > > for (i = 0; i < depth_from; i++) > - len += strlcpy(buf + len, parent_str, > + len += strscpy_mock_strlcpy(buf + len, parent_str, > len < buflen ? buflen - len : 0); > > /* Calculate how many bytes we need for the rest */ > for (i = depth_to - 1; i >= 0; i--) { > for (kn = kn_to, j = 0; j < i; j++) > kn = kn->parent; > - len += strlcpy(buf + len, "/", > + len += strscpy_mock_strlcpy(buf + len, "/", > len < buflen ? buflen - len : 0); > - len += strlcpy(buf + len, kn->name, > + len += strscpy_mock_strlcpy(buf + len, kn->name, > len < buflen ? buflen - len : 0); > } Ditto, please convert all the users accordingly. If that's not feasible, I think it'd be better to leave it as-is. I don't see how the new code is better. > @@ -851,7 +858,7 @@ static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, > > spin_lock_irq(&kernfs_pr_cont_lock); > > - len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); > + len = strscpy_mock_strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); > > if (len >= sizeof(kernfs_pr_cont_buf)) { > spin_unlock_irq(&kernfs_pr_cont_lock); This is an easy conversion to strscpy(). Thanks. -- tejun