Function shm_prison_set

freebsd/kern/sysv_shm.c:1133–1219

}

static int
shm_prison_set(void *obj, void *data)
{
	struct prison *pr = obj;
	struct prison *tpr, *orpr, *nrpr, *trpr;
	struct vfsoptlist *opts = data;
	void *rsv;
	int jsys, descend;

	/*
	 * sysvshm controls which jail is the root of the associated segments
	 * (this jail or same as the parent), or if the feature is available
	 * at all.
	 */
	if (vfs_copyopt(opts, "sysvshm", &jsys, sizeof(jsys)) == ENOENT)
		jsys = vfs_flagopt(opts, "allow.sysvipc", NULL, 0)
		    ? JAIL_SYS_INHERIT
		    : vfs_flagopt(opts, "allow.nosysvipc", NULL, 0)
		    ? JAIL_SYS_DISABLE
		    : -1;
	if (jsys == JAIL_SYS_DISABLE) {
		prison_lock(pr);
		orpr = osd_jail_get(pr, shm_prison_slot);
		if (orpr != NULL)
			osd_jail_del(pr, shm_prison_slot);
		prison_unlock(pr);
		if (orpr != NULL) {
			if (orpr == pr)
				shm_prison_cleanup(pr);
			/* Disable all child jails as well. */
			FOREACH_PRISON_DESCENDANT(pr, tpr, descend) {
				prison_lock(tpr);
				trpr = osd_jail_get(tpr, shm_prison_slot);
				if (trpr != NULL) {
					osd_jail_del(tpr, shm_prison_slot);
					prison_unlock(tpr);
					if (trpr == tpr)
						shm_prison_cleanup(tpr);
				} else {
					prison_unlock(tpr);
					descend = 0;
				}
			}
		}
	} else if (jsys != -1) {
		if (jsys == JAIL_SYS_NEW)
			nrpr = pr;
		else {
			prison_lock(pr->pr_parent);
			nrpr = osd_jail_get(pr->pr_parent, shm_prison_slot);
			prison_unlock(pr->pr_parent);
		}
		rsv = osd_reserve(shm_prison_slot);
		prison_lock(pr);
		orpr = osd_jail_get(pr, shm_prison_slot);
		if (orpr != nrpr)
			(void)osd_jail_set_reserved(pr, shm_prison_slot, rsv,
			    nrpr);