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Message-ID: <201907030912.30942E2FF@keescook>
Date: Wed, 3 Jul 2019 09:49:02 -0700
From: Kees Cook <keescook@...omium.org>
To: Nitin Gote <nitin.r.gote@...el.com>
Cc: jannh@...gle.com, kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v2] checkpatch: Added warnings in favor of strscpy().
On Wed, Jul 03, 2019 at 11:50:14AM +0530, Nitin Gote wrote:
> Added warnings in checkpatch.pl script to :
>
> 1. Deprecate strcpy() in favor of strscpy().
> 2. Deprecate strlcpy() in favor of strscpy().
> 3. Deprecate strncpy() in favor of strscpy() or strscpy_pad().
>
> Updated strncpy() section in Documentation/process/deprecated.rst
> to cover strscpy_pad() case.
>
> Signed-off-by: Nitin Gote <nitin.r.gote@...el.com>
Acked-by: Kees Cook <keescook@...omium.org>
This looks good. I think you're ready for sending this upstream. Please
see:
https://www.kernel.org/doc/html/latest/process/submitting-patches.html
The To: should likely be:
Andrew Morton <akpm@...ux-foundation.org>
and I recommend CC to:
Jonathan Corbet <corbet@....net>
Andy Whitcroft <apw@...onical.com>
Joe Perches <joe@...ches.com>
linux-doc@...r.kernel.org
linux-kernel@...r.kernel.org
kernel-hardening@...ts.openwall.com
Thanks!
-Kees
> ---
> Documentation/process/deprecated.rst | 6 +++---
> scripts/checkpatch.pl | 4 ++++
> 2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
> index 49e0f64..f564de3 100644
> --- a/Documentation/process/deprecated.rst
> +++ b/Documentation/process/deprecated.rst
> @@ -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
> +:c:func:`strscpy`. If, however, the destination buffer still needs
> +NUL-padding, the safe replacement is :c:func:`strscpy_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
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 342c7c7..2ce2340 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -595,6 +595,10 @@ our %deprecated_apis = (
> "rcu_barrier_sched" => "rcu_barrier",
> "get_state_synchronize_sched" => "get_state_synchronize_rcu",
> "cond_synchronize_sched" => "cond_synchronize_rcu",
> + "strcpy" => "strscpy",
> + "strlcpy" => "strscpy",
> + "strncpy" => "strscpy, strscpy_pad or for non-NUL-terminated strings,
> + strncpy() can still be used, but destinations should be marked with the __nonstring",
> );
>
> #Create a search pattern for all these strings to speed up a loop below
> --
> 2.7.4
--
Kees Cook
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