linux-kernel - Re: [PATCH] ima: Replacing deprecated strlcpy with strscpy ~~~~~~~~~ Replace

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Date:   Fri, 19 Feb 2021 19:38:39 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Palash Oswal <hello@...alpalash.com>
Cc:     Mimi Zohar <zohar@...ux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ima: Replacing deprecated strlcpy with strscpy ~~~~~~~~~
 Replace

Reply-To: 
In-Reply-To: <20210219084038.GA7564@...oswalpalash.com>

On Fri, Feb 19, 2021 at 02:10:38PM +0530, Palash Oswal wrote:
> The strlcpy() function is unsafe in that the source buffer length
> is unbounded or possibly be non NULL terminated. This can cause
> memory over-reads, crashes, etc.
> 
> Link: https://github.com/KSPP/linux/issues/89
> Signed-off-by: Palash Oswal <hello@...alpalash.com>

The long description does not explain what the commit does, and
does not include any details about deprecation of strlcpy(), which
at least I'm not aware of.

I don't think *length* ever is NULL terminated. The first sentence
is somewhat weird. Also strlcpy() does have a bounds check.

Generally, the description and reasoning is sloppy to say the
least.

/Jarkko


> ---
>  security/integrity/ima/ima_api.c    | 2 +-
>  security/integrity/ima/ima_policy.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
> index 1dd70dc68ffd..2f3b8257181d 100644
> --- a/security/integrity/ima/ima_api.c
> +++ b/security/integrity/ima/ima_api.c
> @@ -399,7 +399,7 @@ const char *ima_d_path(const struct path *path, char **pathbuf, char *namebuf)
>  	}
>  
>  	if (!pathname) {
> -		strlcpy(namebuf, path->dentry->d_name.name, NAME_MAX);
> +		strscpy(namebuf, path->dentry->d_name.name, NAME_MAX);
>  		pathname = namebuf;
>  	}
>  
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 9b45d064a87d..010839aef6ba 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -791,7 +791,7 @@ static int __init ima_init_arch_policy(void)
>  		char rule[255];
>  		int result;
>  
> -		result = strlcpy(rule, *rules, sizeof(rule));
> +		strscpy(rule, *rules, sizeof(rule));
>  
>  		INIT_LIST_HEAD(&arch_policy_entry[i].list);
>  		result = ima_parse_rule(rule, &arch_policy_entry[i]);
> 
> base-commit: f6692213b5045dc461ce0858fb18cf46f328c202
> -- 
> 2.27.0
> 
>