Re: [PATCH v2] setsebool: support use of -P on SELinux-disabled hosts

[Stephen Smalley <sds@xxxxxxxxxxxxx>]

On 1/14/19 6:31 AM, Petr Lautrbach wrote:
> Stephen Smalley <sds@xxxxxxxxxxxxx> writes:
>
> > As reported in #123, setsebool immediately exits with an error if
> > SELinux is disabled, preventing its use for setting boolean persistent
> > values.  In contrast, semanage boolean -m works on SELinux-disabled
> > hosts.  Change setsebool so that it can be used with the -P option
> > (persistent changes) even if SELinux is disabled.  In the SELinux-disabled
> > case, skip setting of active boolean values, but set the persistent value
> > in the policy store.  Policy reload is automatically disabled by libsemanage
> > when SELinux is disabled, so we only need to call semanage_set_reload()
> > if -N was used.
>
> So right now, `setsebool -N` and `semanage boolean -N` have the same effect that
> `load_policy` is not run, but the value of the boolean is changed when
> SELinux is enabled so it affects the system. Would it make sense to use
> -N to just change values in the store and do not change the value in the
> running kernel? E.g.
>
> --- a/policycoreutils/setsebool/setsebool.c
> +++ b/policycoreutils/setsebool/setsebool.c
> @@ -187,11 +187,14 @@ static int semanage_set_boolean_list(size_t boolcnt,
>                                                    boolean) < 0)
>                          goto err;
>   
> -               if (enabled && semanage_bool_set_active(handle, bool_key, boolean) < 0) {
> -                       fprintf(stderr, "Failed to change boolean %s: %m\n",
> -                               boollist[j].name);
> -                       goto err;
> -               }
> +               if (no_reload)
> +                       semanage_set_reload(handle, 0);
> +               else
> +                       if (enabled && semanage_bool_set_active(handle, bool_key, boolean) < 0) {
> +                               fprintf(stderr, "Failed to change boolean %s: %m\n",
> +                                                               boollist[j].name);
> +                               goto err;
> +                       }
>
>
> A similar patch would need to be applied to seobject.py as well in this case.

That makes sense to me logically (in fact, I don't really understand why 
setsebool w/o -P would ever trigger a reload), but I guess the concern 
is whether any existing users rely on the current behavior, e.g. the 
%post scriptlet in container-selinux that led to this issue.

> > Fixes: https://github.com/SELinuxProject/selinux/issues/123
> > Signed-off-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
> > ---
> > v2 changes setsebool to only call semanage_set_reload() if -N was specified;
> > otherwise we can use the libsemanage defaults just as we do in semodule
> > and semanage.
> >   policycoreutils/setsebool/setsebool.c | 15 ++++++---------
> >   1 file changed, 6 insertions(+), 9 deletions(-)
> >
> > diff --git a/policycoreutils/setsebool/setsebool.c b/policycoreutils/setsebool/setsebool.c
> > index 53d3566c..a5157efc 100644
> > --- a/policycoreutils/setsebool/setsebool.c
> > +++ b/policycoreutils/setsebool/setsebool.c
> > @@ -18,7 +18,7 @@
> >   #include <errno.h>
> >   
> >   int permanent = 0;
> > -int reload = 1;
> > +int no_reload = 0;
> >   int verbose = 0;
> >   
> >   int setbool(char **list, size_t start, size_t end);
> > @@ -38,11 +38,6 @@ int main(int argc, char **argv)
> >   	if (argc < 2)
> >   		usage();
> >   
> > -	if (is_selinux_enabled() <= 0) {
> > -		fputs("setsebool:  SELinux is disabled.\n", stderr);
> > -		return 1;
> > -	}
> > -
> >   	while (1) {
> >   		clflag = getopt(argc, argv, "PNV");
> >   		if (clflag == -1)
> > @@ -53,7 +48,7 @@ int main(int argc, char **argv)
> >   			permanent = 1;
> >   			break;
> >   		case 'N':
> > -			reload = 0;
> > +			no_reload = 1;
> >   			break;
> >   		case 'V':
> >   			verbose = 1;
> > @@ -130,6 +125,7 @@ static int semanage_set_boolean_list(size_t boolcnt,
> >   	semanage_bool_key_t *bool_key = NULL;
> >   	int managed;
> >   	int result;
> > +	int enabled = is_selinux_enabled();
> >   
> >   	handle = semanage_handle_create();
> >   	if (handle == NULL) {
> > @@ -191,7 +187,7 @@ static int semanage_set_boolean_list(size_t boolcnt,
> >   						  boolean) < 0)
> >   			goto err;
> >   
> > -		if (semanage_bool_set_active(handle, bool_key, boolean) < 0) {
> > +		if (enabled && semanage_bool_set_active(handle, bool_key, boolean) < 0) {
> >   			fprintf(stderr, "Failed to change boolean %s: %m\n",
> >   				boollist[j].name);
> >   			goto err;
> > @@ -202,7 +198,8 @@ static int semanage_set_boolean_list(size_t boolcnt,
> >   		boolean = NULL;
> >   	}
> >   
> > -	semanage_set_reload(handle, reload);
> > +	if (no_reload)
> > +		semanage_set_reload(handle, 0);
> >   	if (semanage_commit(handle) < 0)
> >   		goto err;