linux-hardening - Re: [PATCH] KEYS: Replace all non-returning strlcpy with strscpy

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Date:   Thu, 18 May 2023 21:01:38 +0300
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     "Azeem Shaikh" <azeemshaikh38@...il.com>,
        "David Howells" <dhowells@...hat.com>
Cc:     <linux-hardening@...r.kernel.org>, <keyrings@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, "Paul Moore" <paul@...l-moore.com>,
        "James Morris" <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH] KEYS: Replace all non-returning strlcpy with strscpy

On Thu May 18, 2023 at 7:15 AM EEST, Azeem Shaikh wrote:
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
> No return values were used, so direct replacement is safe.
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
>
> Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
> ---
>  security/keys/request_key_auth.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
> index 41e9735006d0..8f33cd170e42 100644
> --- a/security/keys/request_key_auth.c
> +++ b/security/keys/request_key_auth.c
> @@ -178,7 +178,7 @@ struct key *request_key_auth_new(struct key *target, const char *op,
>  	if (!rka->callout_info)
>  		goto error_free_rka;
>  	rka->callout_len = callout_len;
> -	strlcpy(rka->op, op, sizeof(rka->op));
> +	strscpy(rka->op, op, sizeof(rka->op));
>  
>  	/* see if the calling process is already servicing the key request of
>  	 * another process */


Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>

BR, Jarkko