From: Kees Cook <keescook@chromium.org>
To: Justin Stitt <justinstitt@google.com>
Cc: Tyler Hicks <code@tyhicks.com>,
ecryptfs@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] fs: ecryptfs: replace deprecated strncpy with strscpy
Date: Thu, 28 Mar 2024 21:08:58 -0700 [thread overview]
Message-ID: <202403282108.7FF7CE596C@keescook> (raw)
In-Reply-To: <20240321-strncpy-fs-ecryptfs-crypto-c-v1-1-d78b74c214ac@google.com>
On Thu, Mar 21, 2024 at 12:38:54AM +0000, Justin Stitt wrote:
> strncpy() is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces. A good alternative is strscpy() as it guarantees
> NUL-termination on the destination buffer.
>
> In crypto.c:
> We expect cipher_name to be NUL-terminated based on its use with
> the C-string format specifier %s and with other string apis like
> strlen():
> | printk(KERN_ERR "Error attempting to initialize key TFM "
> | "cipher with name = [%s]; rc = [%d]\n",
> | tmp_tfm->cipher_name, rc);
> and
> | int cipher_name_len = strlen(cipher_name);
>
> In main.c:
> We can remove the manual NUL-byte assignments as well as the pointers to
> destinations (which I assume only existed to trim down on line length?)
> in favor of directly using the destination buffer which allows the
> compiler to get size information -- enabling the usage of the new
> 2-argument strscpy().
>
> Note that this patch relies on the _new_ 2-argument versions of
> strscpy() and strscpy_pad() introduced in Commit e6584c3964f2f ("string:
> Allow 2-argument strscpy()").
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
Looks correct. I don't see any need for padding.
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
next prev parent reply other threads:[~2024-03-29 4:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-21 0:38 [PATCH] fs: ecryptfs: replace deprecated strncpy with strscpy Justin Stitt
2024-03-29 4:08 ` Kees Cook [this message]
2024-04-24 23:57 ` Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=202403282108.7FF7CE596C@keescook \
--to=keescook@chromium.org \
--cc=code@tyhicks.com \
--cc=ecryptfs@vger.kernel.org \
--cc=justinstitt@google.com \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).