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

From: Jarkko Sakkinen
Date: Fri Feb 19 2021 - 12:40:00 EST


Reply-To:
In-Reply-To: <20210219084038.GA7564@xxxxxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>

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
>
>