fix(instances): the VM page offers only the controls the user may use

The page showed controls the backend then refused: power to global
viewers, the console, virt-viewer and VDI controls and the root password
and SSH key forms to viewers, resize to staff, per-vCPU hotplug, video
model and guest agent to non-superusers, clone and options by the clone
permission alone, snapshots without change permission. The page now asks
the views' own rules (owner, is_change, clone and snapshot permissions,
the template rules). OS info, opened from the header, is there for every
viewer; the XML editor and tab restoring after a redirect no longer throw
when a pane is absent; Settings opens on the first section the user has.
The authorization matrix also covers a template VM, the template clone
rule and the template snapshot rule.

instances/templates/instance.html

@@ -85,7 +85,7 @@
                     {% trans "Resize" %}
                 </button>
             </li>
-            {% if allow_admin_or_not_template and 'instances.snapshot_instances' in perms %}
+            {% if can_snapshot %}
             <li class="nav-item" role="presentation">
                 <button class="nav-link action-button" id="snapshots-tab" aria-controls="snapshots" data-bs-toggle="pill" data-bs-target="#snapshots" type="button" role="tab" aria-selected="false">
                     <span id="action-block" aria-hidden="true">{% bs_icon 'camera' size='2em'%} </span>
@@ -93,12 +93,14 @@
                 </button>
             </li>
             {% endif %}
+            {% if show_settings %}
             <li class="nav-item" role="presentation">
                 <button class="nav-link action-button" id="settings-tab" aria-controls="settings" data-bs-toggle="pill" data-bs-target="#settings" type="button" role="tab" aria-selected="false">
                     <span id="action-block" aria-hidden="true">{% bs_icon 'gear-wide-connected' size='2em'%} </span>
                     {% trans "Settings" %}
                 </button>
             </li>
+            {% endif %}
             <li class="nav-item" role="presentation">
                 <button class="nav-link action-button" id="graphics-tab" aria-controls="graphics" data-bs-toggle="pill" data-bs-target="#graphics" type="button" role="tab" aria-selected="false">
                     <span id="action-block" aria-hidden="true">{% bs_icon 'bar-chart-line' size='2em'%} </span>
@@ -117,8 +119,8 @@
             {% include 'instances/power_tab.html' %}
             {% include 'instances/access_tab.html' %}
             {% include 'instances/resize_tab.html' %}
-            {% include 'instances/snapshots_tab.html' %}
-            {% include 'instances/settings_tab.html' %}
+            {% if can_snapshot %}{% include 'instances/snapshots_tab.html' %}{% endif %}
+            {% if show_settings %}{% include 'instances/settings_tab.html' %}{% endif %}
             {% include 'instances/stats_tab.html' %}
             {% include 'instances/destroy_tab.html' %}
         </div>
@@ -156,13 +158,16 @@
     }
 </script>
 <script>
-    var editor = ace.edit("editor");
-    editor.getSession().setMode("ace/mode/xml");
+    // The XML editor exists only for superusers
+    if (document.getElementById("editor")) {
+        var editor = ace.edit("editor");
+        editor.getSession().setMode("ace/mode/xml");
 
-    var input = $('input[name="inst_xml"]');
+        var input = $('input[name="inst_xml"]');
         editor.getSession().on("change", function () {
-        input.val(editor.getSession().getValue());
-    });
+            input.val(editor.getSession().getValue());
+        });
+    }
 </script>
 <script>
     function random_mac(net) {
@@ -269,6 +274,7 @@
             $("#video_model_select option[value='" + video_model + "']").prop('selected', true);
         }
     });
+{% if can_open_console %}
     $(document).ready(function () {
         // set vdi url
         $.get("{% url 'vdi_url' compute.id instance.name %}", function(data) {
@@ -276,6 +282,7 @@
             $("#vdi_url").attr("href", data);
         });
     });
+{% endif %}
 {% if request.user.is_superuser %}
     $(document).ready(function () {
         random_mac('clone-net-mac-0');
@@ -669,58 +676,41 @@
     });
 </script>
 <script>
+    // Open the tab (and sub-tab) a redirect points to with #<pane id>
+    function show_tab(target) {
+        var button = document.querySelector('button[data-bs-target="' + target + '"]');
+        if (button) {
+            bootstrap.Tab.getOrCreateInstance(button).show();
+        }
+    }
     var hash = location.hash;
-    if (~$.inArray(hash, ['#poweron', '#poweroff', '#powercycle', '#suspend', '#resume'])) {
-        var btnsect = $('#navbtn>li>a');
-        $(btnsect).each(function () {
-            if ($(this).attr('href') === '#power') {
-                $(this).trigger('click');
-            }
-        });
+    var parents = {
+        '#poweron': '#power', '#poweroff': '#power', '#powercycle': '#power', '#suspend': '#power', '#resume': '#power',
+        '#resizevm_cpu': '#resize', '#resizevm_mem': '#resize', '#resizevm_disk': '#resize',
+        '#boot_opt': '#settings', '#disks': '#settings', '#network': '#settings', '#clone': '#settings',
+        '#xmledit': '#settings', '#vncsettings': '#settings', '#migrate': '#settings', '#options': '#settings',
+        '#users': '#settings',
+        '#takesnapshot': '#snapshots', '#takeextsnapshot': '#snapshots', '#managesnapshot': '#snapshots'
+    };
+    if (hash === '#resize') {
+        show_tab('#resize');
+    } else if (parents[hash]) {
+        show_tab(parents[hash]);
+        show_tab(hash);
     }
-    if (~$.inArray(hash, ['#resize', "#resizevm_cpu", "#resizevm_mem", "#resizevm_disk"])) {
-        var btnsect = $('#navbtn>li>a');
-        $(btnsect).each(function () {
-            if ($(this).attr('href') === '#resize') {
-                $(this).trigger('click');
-            }
-        });
-    }
-    if (~$.inArray(hash, ['#osinfo', '#boot_opt', "#disks", '#network', '#clone', '#xmledit', '#vncsettings', '#migrate', '#options', '#users'])) {
-        var btnsect = $('#navbtn>li>a');
-        $(btnsect).each(function () {
-            if ($(this).attr('href') === '#settings') {
-                $(this).trigger('click');
-            }
-        });
-
-        var btn = $('#settings>div>ul>li>a');
-        $(btn).each(function () {
-            if ($(this).attr('href') === hash) {
-                $(this).trigger('click');
-            }
-        });
-    }
-    if (~$.inArray(hash, ['#takesnapshot', "#takeextsnapshot", "#managesnapshot"])) {
-        var btnsect = $('#navbtn>li>a');
-        $(btnsect).each(function () {
-            if ($(this).attr('href') === '#snapshots') {
-                $(this).trigger('click');
-            }
-        });
-
-        var btn = $('#snapshots>div>ul>li>a');
-        $(btn).each(function () {
-            if ($(this).attr('href') === hash) {
-                $(this).trigger('click');
-            }
-        });
+    // Settings opens on its first section the user has (Boot is superuser-only)
+    var settings_tabs = document.querySelector('#settings .nav-tabs');
+    if (settings_tabs && !settings_tabs.querySelector('.nav-link.active')) {
+        var first = settings_tabs.querySelector('.nav-link:not(#osinfo-tab)');
+        if (first) {
+            bootstrap.Tab.getOrCreateInstance(first).show();
+        }
     }
 </script>
 <script>
     function get_osinfo() {
-        document.querySelector("#settings-tab").click();
-        document.querySelector("#osinfo-tab").click();
+        show_tab('#settings');
+        show_tab('#osinfo');
 
         $.getJSON("{% url 'instances:osinfo' instance.id %}", function (data) {
             $.each(data, function() {

instances/templates/instances/access_tab.html

@@ -7,21 +7,21 @@
                 {% trans "Console" %}
             </button>
         </li>
-        {% if app_settings.SHOW_ACCESS_ROOT_PASSWORD == 'True' %}
+        {% if app_settings.SHOW_ACCESS_ROOT_PASSWORD == 'True' and can_change %}
         <li class="nav-item" role="presentation">
             <button class="nav-link" data-bs-toggle="tab" data-bs-target="#rootpasswd" type="button" role="tab" aria-controls="rootpasswd" aria-selected="false">
                 {% trans "Root Password" %}
             </button>
         </li>
         {% endif %}
-        {% if app_settings.SHOW_ACCESS_SSH_KEYS == 'True' %}
+        {% if app_settings.SHOW_ACCESS_SSH_KEYS == 'True' and can_change %}
         <li class="nav-item" role="presentation">
             <button class="nav-link" data-bs-toggle="tab" data-bs-target="#sshkeys" type="button" role="tab" aria-controls="sshkeys" aria-selected="false">
                 {% trans "SSH Keys" %}
             </button>
         </li>
         {% endif %}
-        {% if instance.status == 1 %}
+        {% if instance.status == 1 and can_open_console %}
         <li class="nav-item" role="presentation">
             <button class="nav-link" data-bs-toggle="tab" data-bs-target="#vdiconsole" type="button" role="tab" aria-controls="vdiconsole" aria-selected="false">
                 {% trans "VDI" %}
@@ -34,6 +34,9 @@
         <div role="tabpanel" class="tab-pane tab-pane-bordered active" id="vnconsole">
             <p>{% blocktrans with type=instance.console_type|upper %} This action opens a new window with a {{ type }} connection to the console of the instance.{% endblocktrans %}
             </p>
+            {% if not can_open_console %}
+            <p>{% trans "Only the owners of this instance and administrators can open its console." %}</p>
+            {% else %}
             {% if instance.console_type == 'vnc' %}
                 <div class="form-check form-switch">
                     <input class="form-check-input" type="checkbox" name="scale"
@@ -80,9 +83,10 @@
             {% else %}
             <button class="btn btn-lg btn-success float-end disabled">{% trans "Console" %}</button>
             {% endif %}
+            {% endif %}
             <div class="clearfix"></div>
         </div>
-        {% if app_settings.SHOW_ACCESS_ROOT_PASSWORD == 'True' %}
+        {% if app_settings.SHOW_ACCESS_ROOT_PASSWORD == 'True' and can_change %}
         <div role="tabpanel" class="tab-pane tab-pane-bordered" id="rootpasswd">
             <p>{% trans "You need shut down your instance and enter a new root password." %}</p>
             <form action="{% url 'instances:rootpasswd' instance.id %}" method="post"
@@ -105,7 +109,7 @@
             <div class="clearfix"></div>
         </div>
         {% endif %}
-        {% if app_settings.SHOW_ACCESS_SSH_KEYS == 'True' %}
+        {% if app_settings.SHOW_ACCESS_SSH_KEYS == 'True' and can_change %}
         <div role="tabpanel" class="tab-pane tab-pane-bordered" id="sshkeys">
             <p>{% trans "You need shut down your instance and choose your public key." %}</p>
             <form action="{% url 'instances:add_public_key' instance.id %}"method="post"
@@ -134,7 +138,7 @@
             <div class="clearfix"></div>
         </div>
         {% endif %}
-        {% if instance.status == 1 %}
+        {% if instance.status == 1 and can_open_console %}
         <div role="tabpanel" class="tab-pane tab-pane-bordered" id="vdiconsole">
             <p>{% trans "This action opens a remote viewer with a connection to the console of the instance." %}</p>
             <div class="input-group">
@@ -150,6 +154,7 @@
     </div>
 </div>
 {% block script %}
+{% if can_open_console %}
 <script>
     function open_console(view_style) {
         const sc = $("#scale").is(':checked');
@@ -160,4 +165,5 @@
         window.open(url, '', 'width=850,height=600')
     }
 </script>
+{% endif %}
 {% endblock %}

instances/templates/instances/power_tab.html

@@ -1,5 +1,8 @@
 {% load i18n %}
 <div class="tab-pane active" id="power" role="tabpanel">
+    {% if not can_power %}
+    <p>{% trans "Only the owners of this instance and administrators can change its power state." %}</p>
+    {% else %}
     <!-- Nav tabs -->
     <ul class="nav nav-tabs" role="tablist" aria-label="Instance power actions">
         {% if instance.status == 1 or instance.status == 2 %}
@@ -144,4 +147,5 @@
             </div>
         {% endif %}
     </div>
+    {% endif %}
 </div>

instances/templates/instances/resize_tab.html

@@ -22,7 +22,7 @@
     <!-- Tab panes -->
     <div class="tab-content">
         <div role="tabpanel" class="tab-pane tab-pane-bordered active" id="resizevm_cpu">
-            {% if request.user.is_superuser or request.user.is_staff or userinstance.is_change %}
+            {% if can_change %}
                 {% if instance.status == 5 or not instance.vcpus %}
                 <form action="{% url 'instances:resizevm_cpu' instance.id %}" method="post" role="form" aria-label="Resize instance cpu form">{% csrf_token %}
                     <p class="fw-bold">{% trans "Logical host CPUs" %} : {{ vcpu_host }}</p>
@@ -62,6 +62,7 @@
                     <p class="fw-bold">{% trans "Logical Instance Active/Maximum CPUs" %} : {{ instance.cur_vcpu }} / {{ instance.vcpu }} </p>
                     <div class="col-sm-3"></div>
                     <div class="col-sm-6">
+                        {% if request.user.is_superuser %}
                         {% for id, vcpu in instance.vcpus.items %}
                             <form action="{% url 'instances:set_vcpu' instance.id %}" method="post" role="form" aria-label="Resize instance cpu form">{% csrf_token %}
                             <div class="d-grid col-sm-3">
@@ -76,6 +77,7 @@
                             </div>
                             </form>
                         {% endfor %}
+                        {% endif %}
                     </div>
                     <div class="col-sm-3"></div>
                 {% endif %}
@@ -86,7 +88,7 @@
             <div class="clearfix"></div>
         </div>
         <div role="tabpanel" class="tab-pane tab-pane-bordered" id="resizevm_mem">
-            {% if request.user.is_superuser or request.user.is_staff or userinstance.is_change %}
+            {% if can_change %}
                 <form action="{% url 'instances:resize_memory' instance.id %}" method="post" role="form" aria-label="Resize instance memory form">
                     {% csrf_token %}
                     <p class="fw-bold">{% trans "Total host memory" %}: {{ memory_host|filesizeformat }}</p>
@@ -127,7 +129,7 @@
             <div class="clearfix"></div>
         </div>
         <div role="tabpanel" class="tab-pane tab-pane-bordered" id="resizevm_disk">
-            {% if request.user.is_superuser or request.user.is_staff or userinstance.is_change %}
+            {% if can_change %}
                 <form action="{% url 'instances:resize_disk' instance.id %}" method="post" role="form" aria-label="Resize instance disk form">
                     {% csrf_token %}
                     <p class="fw-bold">{% trans "Disk allocation (GB)" %}:</p>

instances/templates/instances/settings_tab.html

@@ -4,14 +4,14 @@
 <div class="tab-pane" id="settings" role="tabpanel">
     <!-- Nav tabs -->
     <ul class="nav nav-tabs" role="tablist" aria-label="Instance settings">
-        {% if request.user.is_superuser %}
-            {% if instance.guest_agent_ready %}
+        {% if instance.guest_agent_ready %}
             <li class="nav-item" role="presentation">
                 <button class="px-1 nav-link" data-bs-toggle="tab" id="osinfo-tab" data-bs-target="#osinfo" type="button" role="tab" aria-controls="osinfo" aria-selected="false" onclick="get_osinfo();">
                     <span>{% bs_icon 'info-circle' %} </span>
                 </button>
             </li>
-            {% endif %}
+        {% endif %}
+        {% if request.user.is_superuser %}
             <li class="nav-item" role="presentation">
                 <button class="nav-link active" data-bs-toggle="tab" data-bs-target="#boot_opt" type="button" role="tab" aria-controls="boot_opt" aria-selected="true">
                     {% trans "Boot" %}
@@ -37,7 +37,7 @@
                 </button>
             </li>
         {% endif %}
-        {% if perms.instances.clone_instances %}
+        {% if can_clone %}
             <li class="nav-item" role="presentation">
                 <button class="nav-link" data-bs-toggle="tab" data-bs-target="#clone" type="button" role="tab" aria-controls="clone" aria-selected="false">
                     {% trans "Clone" %}
@@ -56,7 +56,7 @@
                 </button>
             </li>
         {% endif %}
-        {% if perms.instances.clone_instances %}
+        {% if can_change %}
             <li class="nav-item" role="presentation">
                 <button class="nav-link" data-bs-toggle="tab" data-bs-target="#options" type="button" role="tab" aria-controls="options" aria-selected="false">
                     {% trans "Options" %}
@@ -73,8 +73,10 @@
     </ul>
     <!-- Tab panes -->
     <div class="tab-content">
-        {% if request.user.is_superuser %}
+        {% if instance.guest_agent_ready %}
         {% include 'instances/info_tab.html' %}
+        {% endif %}
+        {% if request.user.is_superuser %}
         <div role="tabpanel" class="tab-pane tab-pane-bordered active" id="boot_opt">
             <p class="fw-bold">{% trans 'Autostart' %}</p>
                 <div class="row">
@@ -716,7 +718,7 @@
             <div class="clearfix"></div>
         </div>
         {% endif %}
-        {% if perms.instances.clone_instances %}
+        {% if can_clone %}
         <div role="tabpanel" class="tab-pane tab-pane-bordered" id="clone">
             <p class="fw-bold">{% trans "Create a clone" %}</p>
             <form class="form" action="{% url 'instances:clone' instance.id %}" method="post" role="form" aria-label="Create clone form">{% csrf_token %}
@@ -811,6 +813,8 @@
             </form>
             <div class="clearfix"></div>
         </div>
+        {% endif %}
+        {% if can_change %}
         <div role="tabpanel" class="tab-pane tab-pane-bordered" id="options">
             <p>{% trans "To set instance template name description, shutdown the instance." %}</p>
             <form action="{% url 'instances:change_options' instance.id %}" method="post" role="form" aria-label="Set instance template name description form">{% csrf_token %}
@@ -847,7 +851,7 @@
                     </div>
                 </div>
             </form>
-        
+            {% if request.user.is_superuser %}
             <p class="fw-bold">{% trans "To set instance video model, shutdown the instance." %}</p>
             <form action="{% url 'instances:set_video_model' instance.id %}" method="post" role="form" aria-label="Set instance video model form">{% csrf_token %}
                 <div class="row">
@@ -914,6 +918,7 @@
                     </div>
                 </div>
             </form>
+            {% endif %}
             <div class="clearfix"></div>
         </div>
         {% endif %}

instances/test_page_controls.py

@@ -0,0 +1,169 @@
+"""
+The VM page renders a control only for users the backend lets use it:
+power to superusers and owners; the console, virt-viewer file and VDI URL to
+superusers and owners (can_open_console); root password, SSH key, resize and
+options to superusers and owners with is_change; per-vCPU hotplug, video
+model and guest agent to superusers; clone with clone_instances on a template
+or with is_change; snapshots with snapshot_instances and is_change, on a
+template only for staff. is_staff and the global view_instances permission
+alone are read-only.
+"""
+from unittest.mock import PropertyMock, patch
+
+from django.contrib.auth import get_user_model
+from django.contrib.auth.models import Permission
+from django.test import TestCase
+from django.urls import reverse
+from lxml import html as lxml_html
+
+from accounts.models import UserInstance
+from appsettings.models import AppSettings
+from computes.models import Compute
+from instances.models import Instance
+
+CONSOLE = {"console", "vv file", "vdi"}
+POWER = {"power"}
+CHANGE = {"root password", "ssh key", "resize", "options"}
+SUPERUSER_ONLY = {"vcpu hotplug", "video model", "guest agent"}
+
+
+class PageControls:
+    def setUp(self):
+        AppSettings.objects.filter(
+            key__in=["SHOW_ACCESS_ROOT_PASSWORD", "SHOW_ACCESS_SSH_KEYS"]
+        ).update(value="True")
+        self.compute = Compute.objects.create(
+            name="ctl-compute", hostname="127.0.0.1:1", login="root", password="", type=1
+        )
+        self.instance = Instance.objects.create(
+            compute=self.compute, name="ctl-vm", uuid="dddddddd-eeee-ffff-0000-111111111111"
+        )
+
+    def user(self, name, staff=False, perms=(), owner=None):
+        user = get_user_model().objects.create_user(name, password="x", is_staff=staff)
+        for codename in perms:
+            user.user_permissions.add(Permission.objects.get(codename=codename))
+        if owner is not None:
+            UserInstance.objects.create(instance=self.instance, user=user, **owner)
+        return user
+
+    def controls(self, user, status=1):
+        self.client.force_login(user)
+        with patch("instances.models.wvmInstance") as mock_wvm, patch.object(
+            Compute, "status", new_callable=PropertyMock, return_value=True
+        ):
+            proxy = mock_wvm.return_value
+            proxy.get_memory.return_value = 1024
+            proxy.get_cur_memory.return_value = 1024
+            proxy.get_max_memory.return_value = 4096
+            proxy.get_vcpu.return_value = 2
+            proxy.get_cur_vcpu.return_value = 1
+            proxy.get_max_cpus.return_value = [1, 2, 3, 4]
+            # a running VM with hotpluggable vCPUs shows the per-vCPU buttons
+            proxy.get_vcpus.return_value = {
+                0: {"enabled": "yes", "hotpluggable": "no"},
+                1: {"enabled": "no", "hotpluggable": "yes"},
+            }
+            for getter in ("get_networks", "get_ifaces", "get_storages", "get_disk_devices",
+                           "get_media_devices", "get_net_devices", "get_snapshot",
+                           "get_external_snapshots"):
+                getattr(proxy, getter).return_value = []
+            proxy.get_console_type.return_value = "vnc"
+            proxy.get_status.return_value = status
+            response = self.client.get(reverse("instances:instance", args=[self.instance.id]))
+        self.assertEqual(response.status_code, 200)
+        doc = lxml_html.fromstring(response.content)
+        pk = self.instance.id
+
+        def form(name):
+            return bool(doc.xpath("//form[@action=$a]", a=reverse(f"instances:{name}", args=[pk])))
+
+        found = {
+            "console": bool(doc.xpath("//button[@id='consoleBtnGroup']")),
+            "vv file": bool(doc.xpath("//a[@href=$a]", a=reverse("instances:getvvfile", args=[pk]))),
+            "vdi": bool(doc.xpath("//*[@id='vdiconsole']")),
+            "power": form("poweroff") or form("poweron"),
+            "root password": form("rootpasswd"),
+            "ssh key": form("add_public_key"),
+            # a running VM with hotplug shows per-vCPU buttons instead of the CPU form
+            "resize": form("resize_memory"),
+            "options": form("change_options"),
+            "vcpu hotplug": form("set_vcpu"),
+            "video model": form("set_video_model"),
+            "guest agent": form("set_guest_agent"),
+            "clone": bool(doc.xpath("//*[@id='clone']")),
+            "snapshots": bool(doc.xpath("//*[@id='snapshots']")),
+        }
+        return {name for name, present in found.items() if present}
+
+
+
+class PageControlsTestCase(PageControls, TestCase):
+    def test_superuser_sees_every_control(self):
+        superuser = get_user_model().objects.create_superuser("ctl_super", "ctl_super@example.com", "x")
+        self.assertEqual(
+            self.controls(superuser), CONSOLE | POWER | CHANGE | SUPERUSER_ONLY | {"clone", "snapshots"}
+        )
+
+    def test_global_viewers_see_nothing_to_act_on(self):
+        perms = ("view_instances", "clone_instances", "snapshot_instances")
+        for user in (self.user("ctl_viewer", perms=perms), self.user("ctl_staff", staff=True, perms=perms)):
+            with self.subTest(user=user.username):
+                self.assertEqual(self.controls(user), set())
+
+    def test_owner_without_change_powers_and_opens_the_console(self):
+        owner = self.user("ctl_owner", perms=("clone_instances", "snapshot_instances"), owner={})
+        self.assertEqual(self.controls(owner), CONSOLE | POWER)
+
+    def test_owner_with_change_gets_change_clone_and_snapshots(self):
+        changer = self.user("ctl_changer", perms=("clone_instances", "snapshot_instances"),
+                            owner={"is_change": True})
+        self.assertEqual(self.controls(changer), CONSOLE | POWER | CHANGE | {"clone", "snapshots"})
+
+    def test_owner_with_change_and_no_extra_permissions(self):
+        changer = self.user("ctl_plain_changer", owner={"is_change": True})
+        self.assertEqual(self.controls(changer), CONSOLE | POWER | CHANGE)
+
+
+class TemplatePageControlsTestCase(PageControls, TestCase):
+    def setUp(self):
+        super().setUp()
+        self.instance.is_template = True
+        self.instance.save()
+
+    def test_a_template_is_cloned_by_viewing_it(self):
+        viewer = self.user("tpl_viewer", perms=("view_instances", "clone_instances"))
+        self.assertEqual(self.controls(viewer, status=5), {"clone"})
+
+    def test_snapshots_of_a_template_are_for_staff_owners(self):
+        perms = ("clone_instances", "snapshot_instances")
+        owner = self.user("tpl_changer", perms=perms, owner={"is_change": True})
+        staff = self.user("tpl_staff_changer", staff=True, perms=perms, owner={"is_change": True})
+        self.assertNotIn("snapshots", self.controls(owner, status=5))
+        self.assertIn("snapshots", self.controls(staff, status=5))
+
+
+class TemplateSnapshotRuleTestCase(PageControls, TestCase):
+    """The backend side of the template rule: only staff owners (and
+    superusers) take a snapshot of a template; other owners with is_change
+    and snapshot_instances are turned away without a libvirt call."""
+
+    def setUp(self):
+        super().setUp()
+        self.instance.is_template = True
+        self.instance.save()
+
+    def snapshot(self, user):
+        self.client.force_login(user)
+        with patch("instances.models.wvmInstance") as mock_wvm:
+            self.client.post(
+                reverse("instances:snapshot", args=[self.instance.id]), {"name": "s1", "description": ""}
+            )
+            return mock_wvm.return_value.create_snapshot.called
+
+    def test_only_staff_owners_snapshot_a_template(self):
+        perms = ("snapshot_instances",)
+        owner = self.user("snap_changer", perms=perms, owner={"is_change": True})
+        staff = self.user("snap_staff_changer", staff=True, perms=perms, owner={"is_change": True})
+        self.assertFalse(self.snapshot(owner))
+        self.assertTrue(self.snapshot(staff))

instances/views.py

@@ -135,6 +135,21 @@ def _instance_page(request, pk, instance, compute):
         )
     except UserInstance.DoesNotExist:
         userinstance = None
+    # The page offers only what the backend allows this user (get_instance
+    # perm_type="change", utils.can_open_console); is_staff and the global
+    # view_instances permission are read-only.
+    can_open_console = utils.can_open_console(request.user, instance)
+    can_power = request.user.is_superuser or userinstance is not None
+    can_change = request.user.is_superuser or bool(userinstance and userinstance.is_change)
+    can_clone = request.user.has_perm("instances.clone_instances") and (instance.is_template or can_change)
+    can_snapshot = (
+        can_change
+        and request.user.has_perm("instances.snapshot_instances")
+        and (request.user.is_superuser or request.user.is_staff or not instance.is_template)
+    )
+    show_settings = (
+        request.user.is_superuser or can_manage_console or can_clone or can_change or instance.guest_agent_ready
+    )
 
     memory_range = [256, 512, 768, 1024, 2048, 3072, 4096, 6144, 8192, 16384]
     if instance.memory not in memory_range:

webvirtcloud/test_authorization_matrix.py

@@ -128,6 +128,12 @@ ROLE_EXPECTATIONS = {
 }
 
 
+# A template VM is reached the same way: on templates, snapshot requests and
+# poweron are no-ops for these roles, and cloning (which none of them may do
+# without instances.clone_instances) has its own rule, see the clone test.
+TEMPLATE_ROLE_EXPECTATIONS = ROLE_EXPECTATIONS
+
+
 def iter_patterns(patterns, prefix="", params=None):
     params = params or {}
     for p in patterns:
@@ -295,6 +301,32 @@ class AuthorizationMatrixTestCase(TestCase):
                     f"{role}: (unexpectedly reachable, unexpectedly denied)",
                 )
 
+    def test_role_reachability_on_a_template_vm(self):
+        self.instance.is_template = True
+        self.instance.save()
+        for role, (is_staff, view_instances, owner_flags, expected) in TEMPLATE_ROLE_EXPECTATIONS.items():
+            with self.subTest(role=role):
+                user = self._make_role_user(role, is_staff, view_instances, owner_flags)
+                reachable = self._reachable(user)
+                self.assertEqual(
+                    (sorted(reachable - expected), sorted(expected - reachable)),
+                    ([], []),
+                    f"template, {role}: (unexpectedly reachable, unexpectedly denied)",
+                )
+
+    def test_a_template_is_cloned_by_viewing_it_a_vm_needs_change(self):
+        user = self._make_role_user("cloner", False, True, None)
+        user.user_permissions.add(Permission.objects.get(codename="clone_instances"))
+        url = reverse("instances:clone", args=[self.instance.pk])
+        for is_template, reached in ((False, False), (True, True)):
+            with self.subTest(is_template=is_template):
+                self.instance.is_template = is_template
+                self.instance.save()
+                with transaction.atomic():
+                    response = self._request(user, url)
+                    transaction.set_rollback(True)
+                self.assertEqual(response.status_code not in DENIED, reached, response.status_code)
+
     def test_owner_power_actions_succeed_through_web_and_api_with_real_test_driver(self):
         import libvirt
         from vrtManager.instance import wvmInstance