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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 AE74EC433DB for ; Mon, 22 Feb 2021 15:18:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4D68164E83 for ; Mon, 22 Feb 2021 15:18:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231510AbhBVPS0 (ORCPT ); Mon, 22 Feb 2021 10:18:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40106 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231253AbhBVPOI (ORCPT ); Mon, 22 Feb 2021 10:14:08 -0500 Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 71002C0617AA for ; Mon, 22 Feb 2021 07:12:53 -0800 (PST) Received: by mail-wm1-x335.google.com with SMTP id p3so3715549wmc.2 for ; Mon, 22 Feb 2021 07:12:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=fvdst0ke5NfAjFDKzfIGeJQUVrU5WqaPoSE7N9OL8Lk=; b=ByUTfEFTtBWT1+a0ndUHz1KXLJgEtcEoht2zWrZ92q9qenV/FW/QItrNFBA9yTMyEu nAxoZ+5AXu3tbOCmNa03Q8qLomQDKJiPxv7eM+CBxbCITTfPr61VnFrxqNLmeXxlwO3D NSpdRj4Lfc+il7l9Z296wz7zGGhZmRTTRRQtCoJTKm2wn4y36LdYZ9EjyeLCQJ4lYebI mYOlnGVeZdOkqV6tdEV2vpkWfpAsY7t3TGFQ6/SyIT186qvj7qU7fcfJQq7KTLm3B5ig A/gh1JqPwarb2PAOkQI97K0mXH1teQXM1pBWa2rExNw6siyEglWGb/yNUH+O8aiFhMYI 3MXA== 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:mime-version:content-transfer-encoding; bh=fvdst0ke5NfAjFDKzfIGeJQUVrU5WqaPoSE7N9OL8Lk=; b=ax8M0AxGHyoXZ10BteaSyYclFBKeSBf9e30eGOZ9B/udGP43JWBuHXaIneVcElQxUr T0kvTezQ/G1bHfmazv0QPZ/ikM+spcCRIdr8FlZW8nz1zgexKWPYUrX5l1uGPqhjFSU+ s266SwW0+mEUayTbEtNmcFVCxv3KIZrBDyi4/P3BnqDb8b+LCmhJLim+AN10jxU4ixzZ pW34bpnifryfozwDQUTWdVhIBfATEvqomMzpw/M7y5xZmmrc8DTgPmq7HliP+NvFsKfl QJEle04AWA34Kwe9aY0GeZ73xcQXojcsH8FJd9cEUIGw9gP9e3F0cFqgQYxQDGVFXpF1 idfw== X-Gm-Message-State: AOAM53299dtfd1OzqFO1CIuDe7enGcf2eRv8YRes1xjdOkhdgSmStw8n Dh/oV4Od+qS/4h23EIiUQAVTKQTkVR3GvUdGbxw= X-Google-Smtp-Source: ABdhPJx3HdU5Aax1CbhYORFA+t6gTkfB7mL2V+O6OWbY4u994qmgJk/1EWCkqEb3ImN5wm0C+wO/uA== X-Received: by 2002:a1c:c906:: with SMTP id f6mr20165149wmb.128.1614006771938; Mon, 22 Feb 2021 07:12:51 -0800 (PST) Received: from debby (176-141-241-253.abo.bbox.fr. [176.141.241.253]) by smtp.gmail.com with ESMTPSA id k15sm27612424wrn.0.2021.02.22.07.12.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Feb 2021 07:12:51 -0800 (PST) From: Romain Perier To: Kees Cook , kernel-hardening@lists.openwall.com, Greg Kroah-Hartman , Tejun Heo Cc: Romain Perier , linux-kernel@vger.kernel.org Subject: [PATCH 08/20] kernfs: Manual replacement of the deprecated strlcpy() with return values Date: Mon, 22 Feb 2021 16:12:19 +0100 Message-Id: <20210222151231.22572-9-romain.perier@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210222151231.22572-1-romain.perier@gmail.com> References: <20210222151231.22572-1-romain.perier@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The strlcpy() reads the entire source buffer first, it is dangerous if the source buffer lenght is unbounded or possibility non NULL-terminated. It can lead to linear read overflows, crashes, etc... As recommended in the deprecated interfaces [1], it should be replaced by strscpy. This commit replaces all calls to strlcpy that handle the return values by the corresponding strscpy calls with new handling of the return values (as it is quite different between the two functions). [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy Signed-off-by: Romain Perier --- fs/kernfs/dir.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 7a53eed69fef..9e65b595d880 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -42,9 +42,9 @@ static bool kernfs_lockdep(struct kernfs_node *kn) static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) { if (!kn) - return strlcpy(buf, "(null)", buflen); + return strscpy(buf, "(null)", buflen); - return strlcpy(buf, kn->parent ? kn->name : "/", buflen); + return strscpy(buf, kn->parent ? kn->name : "/", buflen); } /* kernfs_node_depth - compute depth from @from to @to */ @@ -125,17 +125,18 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, { struct kernfs_node *kn, *common; const char parent_str[] = "/.."; - size_t depth_from, depth_to, len = 0; + size_t depth_from, depth_to; + ssize_t len = 0; int i, j; if (!kn_to) - return strlcpy(buf, "(null)", buflen); + return strscpy(buf, "(null)", buflen); if (!kn_from) kn_from = kernfs_root(kn_to)->kn; if (kn_from == kn_to) - return strlcpy(buf, "/", buflen); + return strscpy(buf, "/", buflen); if (!buf) return -EINVAL; @@ -150,16 +151,16 @@ 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(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(buf + len, "/", len < buflen ? buflen - len : 0); - len += strlcpy(buf + len, kn->name, + len += strscpy(buf + len, kn->name, len < buflen ? buflen - len : 0); } @@ -173,8 +174,8 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, * @buflen: size of @buf * * Copies the name of @kn into @buf of @buflen bytes. The behavior is - * similar to strlcpy(). It returns the length of @kn's name and if @buf - * isn't long enough, it's filled upto @buflen-1 and nul terminated. + * similar to strscpy(). It returns the length of @kn's name and if @buf + * isn't long enough or @buflen is 0, it returns -E2BIG. * * Fills buffer with "(null)" if @kn is NULL. * @@ -858,7 +859,7 @@ static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, const unsigned char *path, const void *ns) { - size_t len; + ssize_t len; char *p, *name; lockdep_assert_held(&kernfs_mutex); @@ -866,9 +867,9 @@ static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, /* grab kernfs_rename_lock to piggy back on kernfs_pr_cont_buf */ spin_lock_irq(&kernfs_rename_lock); - len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); + len = strscpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); - if (len >= sizeof(kernfs_pr_cont_buf)) { + if (len == -E2BIG) { spin_unlock_irq(&kernfs_rename_lock); return NULL; }