From patchwork Sun Jul 28 16:06:08 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nitin Gote X-Patchwork-Id: 11062985 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A9832112C for ; Sun, 28 Jul 2019 16:08:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 98AAB28705 for ; Sun, 28 Jul 2019 16:08:16 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8942E28869; Sun, 28 Jul 2019 16:08:16 +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=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED 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 8835C28705 for ; Sun, 28 Jul 2019 16:08:15 +0000 (UTC) Received: (qmail 30699 invoked by uid 550); 28 Jul 2019 16:08:12 -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 30640 invoked from network); 28 Jul 2019 16:08:11 -0000 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,319,1559545200"; d="scan'208";a="161938649" From: NitinGote To: joe@perches.com, keescook@chromium.org Cc: corbet@lwn.net, akpm@linux-foundation.org, apw@canonical.com, linux-doc@vger.kernel.org, kernel-hardening@lists.openwall.com, Nitin Gote Subject: [PATCH v7] Documentation/checkpatch: Prefer stracpy/strscpy over strcpy/strlcpy/strncpy. Date: Sun, 28 Jul 2019 21:36:08 +0530 Message-Id: <20190728160608.3119-1-nitin.r.gote@intel.com> X-Mailer: git-send-email 2.17.1 X-Virus-Scanned: ClamAV using ClamSMTP From: Nitin Gote Added check in checkpatch.pl to deprecate strcpy(), strlcpy() and strncpy() in favor of stracpy() or strscpy(). Updated Documentation/process/deprecated.rst for stracpy() and strscpy(). Signed-off-by: Nitin Gote --- Change log: v6->v7 - Favored both stracpy() or strscpy(), as stracpy() preferred when the destination is char array (rather than string pointer). v5->v6 - Used stracpy() instead of strscpy(). v4->v5 - Change the subject line as per review comment. - v5 is Reviewed-by: Kees Cook v3->v4 - Removed "c:func:" from deprecated.rst as per review comment. v2->v3 - Avoided use of $check in implementation. - Incorporated trivial comments. v1->v2 - For string related apis, created different %deprecated_string_api and these will get emitted at CHECK Level using command line option -f/--file to avoid bad patched from novice script users. Documentation/process/deprecated.rst | 10 +++++----- scripts/checkpatch.pl | 24 ++++++++++++++++++++++++ 2 files changed, 29 insertions(+), 5 deletions(-) -- 2.17.1 diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst index 49e0f64a3427..b4c82589d301 100644 --- a/Documentation/process/deprecated.rst +++ b/Documentation/process/deprecated.rst @@ -84,7 +84,7 @@ buffer. This could result in linear overflows beyond the end of the buffer, leading to all kinds of misbehaviors. While `CONFIG_FORTIFY_SOURCE=y` and various compiler flags help reduce the risk of using this function, there is no good reason to add new uses of -this function. The safe replacement is :c:func:`strscpy`. +this function. The safe replacement is stracpy() or strscpy(). strncpy() on NUL-terminated strings ----------------------------------- @@ -93,9 +93,9 @@ will be NUL terminated. This can lead to various linear read overflows and other misbehavior due to the missing termination. It also NUL-pads the destination buffer if the source contents are shorter than the destination buffer size, which may be a needless performance penalty for callers using -only NUL-terminated strings. The safe replacement is :c:func:`strscpy`. -(Users of :c:func:`strscpy` still needing NUL-padding will need an -explicit :c:func:`memset` added.) +only NUL-terminated strings. In this case, the safe replacement is +stracpy() or strscpy(). If, however, the destination buffer still needs +NUL-padding, the safe replacement is stracpy_pad(). If a caller is using non-NUL-terminated strings, :c:func:`strncpy()` can still be used, but destinations should be marked with the `__nonstring @@ -107,7 +107,7 @@ strlcpy() :c:func:`strlcpy` reads the entire source buffer first, possibly exceeding the given limit of bytes to copy. This is inefficient and can lead to linear read overflows if a source string is not NUL-terminated. The -safe replacement is :c:func:`strscpy`. +safe replacement is stracpy() or strscpy(). Variable Length Arrays (VLAs) ----------------------------- diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 342c7c781ba5..0e14a1ae6502 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -605,6 +605,20 @@ foreach my $entry (keys %deprecated_apis) { } $deprecated_apis_search = "(?:${deprecated_apis_search})"; +our %deprecated_string_apis = ( + "strcpy" => "stracpy or strscpy", + "strlcpy" => "stracpy or strscpy", + "strncpy" => "stracpy or strscpy - for non-NUL-terminated uses, strncpy dest should be __nonstring", +); + +#Create a search pattern for all these strings apis to speed up a loop below +our $deprecated_string_apis_search = ""; +foreach my $entry (keys %deprecated_string_apis) { + $deprecated_string_apis_search .= '|' if ($deprecated_string_apis_search ne ""); + $deprecated_string_apis_search .= $entry; +} +$deprecated_string_apis_search = "(?:${deprecated_string_apis_search})"; + our $mode_perms_world_writable = qr{ S_IWUGO | S_IWOTH | @@ -6446,6 +6460,16 @@ sub process { "Deprecated use of '$deprecated_api', prefer '$new_api' instead\n" . $herecurr); } +# check for string deprecated apis + if ($line =~ /\b($deprecated_string_apis_search)\b\s*\(/) { + my $deprecated_string_api = $1; + my $new_api = $deprecated_string_apis{$deprecated_string_api}; + my $msg_level = \&WARN; + $msg_level = \&CHK if ($file); + &{$msg_level}("DEPRECATED_API", + "Deprecated use of '$deprecated_string_api', prefer '$new_api' instead\n" . $herecurr); + } + # check for various structs that are normally const (ops, kgdb, device_tree) # and avoid what seem like struct definitions 'struct foo {' if ($line !~ /\bconst\b/ &&