On Wed, Sep 04, 2024 at 06:48:22PM +0800, Mikhail Ivanov wrote:
> Add str2num() helper and replace atoi() with it. atoi() does not provide
> overflow checks, checks of invalid characters in a string and it is
> recommended to use strtol-like functions (Cf. atoi() manpage).
>
> Signed-off-by: Mikhail Ivanov <ivanov.mikhail1@xxxxxxxxxxxxxxxxxxx>
> ---
> samples/landlock/sandboxer.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
> index e8223c3e781a..d4dba9e4ce89 100644
> --- a/samples/landlock/sandboxer.c
> +++ b/samples/landlock/sandboxer.c
> @@ -150,6 +150,26 @@ static int populate_ruleset_fs(const char *const env_var, const int ruleset_fd,
> return ret;
> }
>
> +static int str2num(const char *numstr, unsigned long long *num_dst)
> +{
> + char *endptr = NULL;
> + int err = 1;
> + unsigned long long num;
> +
> + errno = 0;
> + num = strtoull(numstr, &endptr, 0);
> + if (errno != 0)
> + goto out;
> +
> + if (*endptr != '\0')
> + goto out;
> +
> + *num_dst = num;
> + err = 0;
> +out:
> + return err;
> +}
I believe if numstr is the empty string, str2num would return success and set
num_dst to 0, which looks unintentional to me.
Do we not have a better helper for this that we can link from here?
> +
> static int populate_ruleset_net(const char *const env_var, const int ruleset_fd,
> const __u64 allowed_access)
> {
> @@ -168,7 +188,12 @@ static int populate_ruleset_net(const char *const env_var, const int ruleset_fd,
>
> env_port_name_next = env_port_name;
> while ((strport = strsep(&env_port_name_next, ENV_DELIMITER))) {
> - net_port.port = atoi(strport);
> + if (str2num(strport, &net_port.port)) {
> + fprintf(stderr,
> + "Failed to convert \"%s\" into a number\n",
> + strport);
> + goto out_free_name;
> + }
> if (landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
> &net_port, 0)) {
> fprintf(stderr,
> --
> 2.34.1
>
