Merge tag 'v4.17-rc3' into apparmor-next

Linux v4.17-rc3

Merge in v4.17 for LSM updates

Signed-off-by: John Johansen <john.johansen@canonical.com>

4 files changed, 213 insertions, 89 deletions

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index de9e45dca70f..3a4656fb7047 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -366,11 +366,6 @@ static int __klp_enable_patch(struct klp_patch *patch)
 	/*
 	 * A reference is taken on the patch module to prevent it from being
 	 * unloaded.
-	 *
-	 * Note: For immediate (no consistency model) patches we don't allow
-	 * patch modules to unload since there is no safe/sane method to
-	 * determine if a thread is still running in the patched code contained
-	 * in the patch module once the ftrace registration is successful.
 	 */
 	if (!try_module_get(patch->mod))
 		return -ENODEV;
@@ -454,6 +449,8 @@ EXPORT_SYMBOL_GPL(klp_enable_patch);
  * /sys/kernel/livepatch/<patch>
  * /sys/kernel/livepatch/<patch>/enabled
  * /sys/kernel/livepatch/<patch>/transition
+ * /sys/kernel/livepatch/<patch>/signal
+ * /sys/kernel/livepatch/<patch>/force
  * /sys/kernel/livepatch/<patch>/<object>
  * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
  */
@@ -528,11 +525,73 @@ static ssize_t transition_show(struct kobject *kobj,
 			patch == klp_transition_patch);
 }
 
+static ssize_t signal_store(struct kobject *kobj, struct kobj_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct klp_patch *patch;
+	int ret;
+	bool val;
+
+	ret = kstrtobool(buf, &val);
+	if (ret)
+		return ret;
+
+	if (!val)
+		return count;
+
+	mutex_lock(&klp_mutex);
+
+	patch = container_of(kobj, struct klp_patch, kobj);
+	if (patch != klp_transition_patch) {
+		mutex_unlock(&klp_mutex);
+		return -EINVAL;
+	}
+
+	klp_send_signals();
+
+	mutex_unlock(&klp_mutex);
+
+	return count;
+}
+
+static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
+			   const char *buf, size_t count)
+{
+	struct klp_patch *patch;
+	int ret;
+	bool val;
+
+	ret = kstrtobool(buf, &val);
+	if (ret)
+		return ret;
+
+	if (!val)
+		return count;
+
+	mutex_lock(&klp_mutex);
+
+	patch = container_of(kobj, struct klp_patch, kobj);
+	if (patch != klp_transition_patch) {
+		mutex_unlock(&klp_mutex);
+		return -EINVAL;
+	}
+
+	klp_force_transition();
+
+	mutex_unlock(&klp_mutex);
+
+	return count;
+}
+
 static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled);
 static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition);
+static struct kobj_attribute signal_kobj_attr = __ATTR_WO(signal);
+static struct kobj_attribute force_kobj_attr = __ATTR_WO(force);
 static struct attribute *klp_patch_attrs[] = {
 	&enabled_kobj_attr.attr,
 	&transition_kobj_attr.attr,
+	&signal_kobj_attr.attr,
+	&force_kobj_attr.attr,
 	NULL
 };
 
@@ -830,12 +889,7 @@ int klp_register_patch(struct klp_patch *patch)
 	if (!klp_initialized())
 		return -ENODEV;
 
-	/*
-	 * Architectures without reliable stack traces have to set
-	 * patch->immediate because there's currently no way to patch kthreads
-	 * with the consistency model.
-	 */
-	if (!klp_have_reliable_stack() && !patch->immediate) {
+	if (!klp_have_reliable_stack()) {
 		pr_err("This architecture doesn't have support for the livepatch consistency model.\n");
 		return -ENOSYS;
 	}
diff --git a/kernel/livepatch/shadow.c b/kernel/livepatch/shadow.c
index fdac27588d60..83958c814439 100644
--- a/kernel/livepatch/shadow.c
+++ b/kernel/livepatch/shadow.c
@@ -113,8 +113,10 @@ void *klp_shadow_get(void *obj, unsigned long id)
 }
 EXPORT_SYMBOL_GPL(klp_shadow_get);
 
-static void *__klp_shadow_get_or_alloc(void *obj, unsigned long id, void *data,
-		       size_t size, gfp_t gfp_flags, bool warn_on_exist)
+static void *__klp_shadow_get_or_alloc(void *obj, unsigned long id,
+				       size_t size, gfp_t gfp_flags,
+				       klp_shadow_ctor_t ctor, void *ctor_data,
+				       bool warn_on_exist)
 {
 	struct klp_shadow *new_shadow;
 	void *shadow_data;
@@ -125,18 +127,15 @@ static void *__klp_shadow_get_or_alloc(void *obj, unsigned long id, void *data,
 	if (shadow_data)
 		goto exists;
 
-	/* Allocate a new shadow variable for use inside the lock below */
+	/*
+	 * Allocate a new shadow variable.  Fill it with zeroes by default.
+	 * More complex setting can be done by @ctor function.  But it is
+	 * called only when the buffer is really used (under klp_shadow_lock).
+	 */
 	new_shadow = kzalloc(size + sizeof(*new_shadow), gfp_flags);
 	if (!new_shadow)
 		return NULL;
 
-	new_shadow->obj = obj;
-	new_shadow->id = id;
-
-	/* Initialize the shadow variable if data provided */
-	if (data)
-		memcpy(new_shadow->data, data, size);
-
 	/* Look for <obj, id> again under the lock */
 	spin_lock_irqsave(&klp_shadow_lock, flags);
 	shadow_data = klp_shadow_get(obj, id);
@@ -150,6 +149,22 @@ static void *__klp_shadow_get_or_alloc(void *obj, unsigned long id, void *data,
 		goto exists;
 	}
 
+	new_shadow->obj = obj;
+	new_shadow->id = id;
+
+	if (ctor) {
+		int err;
+
+		err = ctor(obj, new_shadow->data, ctor_data);
+		if (err) {
+			spin_unlock_irqrestore(&klp_shadow_lock, flags);
+			kfree(new_shadow);
+			pr_err("Failed to construct shadow variable <%p, %lx> (%d)\n",
+			       obj, id, err);
+			return NULL;
+		}
+	}
+
 	/* No <obj, id> found, so attach the newly allocated one */
 	hash_add_rcu(klp_shadow_hash, &new_shadow->node,
 		     (unsigned long)new_shadow->obj);
@@ -170,26 +185,32 @@ exists:
  * klp_shadow_alloc() - allocate and add a new shadow variable
  * @obj:	pointer to parent object
  * @id:		data identifier
- * @data:	pointer to data to attach to parent
  * @size:	size of attached data
  * @gfp_flags:	GFP mask for allocation
+ * @ctor:	custom constructor to initialize the shadow data (optional)
+ * @ctor_data:	pointer to any data needed by @ctor (optional)
+ *
+ * Allocates @size bytes for new shadow variable data using @gfp_flags.
+ * The data are zeroed by default.  They are further initialized by @ctor
+ * function if it is not NULL.  The new shadow variable is then added
+ * to the global hashtable.
  *
- * Allocates @size bytes for new shadow variable data using @gfp_flags
- * and copies @size bytes from @data into the new shadow variable's own
- * data space.  If @data is NULL, @size bytes are still allocated, but
- * no copy is performed.  The new shadow variable is then added to the
- * global hashtable.
+ * If an existing <obj, id> shadow variable can be found, this routine will
+ * issue a WARN, exit early and return NULL.
  *
- * If an existing <obj, id> shadow variable can be found, this routine
- * will issue a WARN, exit early and return NULL.
+ * This function guarantees that the constructor function is called only when
+ * the variable did not exist before.  The cost is that @ctor is called
+ * in atomic context under a spin lock.
  *
  * Return: the shadow variable data element, NULL on duplicate or
  * failure.
  */
-void *klp_shadow_alloc(void *obj, unsigned long id, void *data,
-		       size_t size, gfp_t gfp_flags)
+void *klp_shadow_alloc(void *obj, unsigned long id,
+		       size_t size, gfp_t gfp_flags,
+		       klp_shadow_ctor_t ctor, void *ctor_data)
 {
-	return __klp_shadow_get_or_alloc(obj, id, data, size, gfp_flags, true);
+	return __klp_shadow_get_or_alloc(obj, id, size, gfp_flags,
+					 ctor, ctor_data, true);
 }
 EXPORT_SYMBOL_GPL(klp_shadow_alloc);
 
@@ -197,37 +218,51 @@ EXPORT_SYMBOL_GPL(klp_shadow_alloc);
  * klp_shadow_get_or_alloc() - get existing or allocate a new shadow variable
  * @obj:	pointer to parent object
  * @id:		data identifier
- * @data:	pointer to data to attach to parent
  * @size:	size of attached data
  * @gfp_flags:	GFP mask for allocation
+ * @ctor:	custom constructor to initialize the shadow data (optional)
+ * @ctor_data:	pointer to any data needed by @ctor (optional)
  *
  * Returns a pointer to existing shadow data if an <obj, id> shadow
  * variable is already present.  Otherwise, it creates a new shadow
  * variable like klp_shadow_alloc().
  *
- * This function guarantees that only one shadow variable exists with
- * the given @id for the given @obj.  It also guarantees that the shadow
- * variable will be initialized by the given @data only when it did not
- * exist before.
+ * This function guarantees that only one shadow variable exists with the given
+ * @id for the given @obj.  It also guarantees that the constructor function
+ * will be called only when the variable did not exist before.  The cost is
+ * that @ctor is called in atomic context under a spin lock.
  *
  * Return: the shadow variable data element, NULL on failure.
  */
-void *klp_shadow_get_or_alloc(void *obj, unsigned long id, void *data,
-			       size_t size, gfp_t gfp_flags)
+void *klp_shadow_get_or_alloc(void *obj, unsigned long id,
+			      size_t size, gfp_t gfp_flags,
+			      klp_shadow_ctor_t ctor, void *ctor_data)
 {
-	return __klp_shadow_get_or_alloc(obj, id, data, size, gfp_flags, false);
+	return __klp_shadow_get_or_alloc(obj, id, size, gfp_flags,
+					 ctor, ctor_data, false);
 }
 EXPORT_SYMBOL_GPL(klp_shadow_get_or_alloc);
 
+static void klp_shadow_free_struct(struct klp_shadow *shadow,
+				   klp_shadow_dtor_t dtor)
+{
+	hash_del_rcu(&shadow->node);
+	if (dtor)
+		dtor(shadow->obj, shadow->data);
+	kfree_rcu(shadow, rcu_head);
+}
+
 /**
  * klp_shadow_free() - detach and free a <obj, id> shadow variable
  * @obj:	pointer to parent object
  * @id:		data identifier
+ * @dtor:	custom callback that can be used to unregister the variable
+ *		and/or free data that the shadow variable points to (optional)
  *
  * This function releases the memory for this <obj, id> shadow variable
  * instance, callers should stop referencing it accordingly.
  */
-void klp_shadow_free(void *obj, unsigned long id)
+void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
 {
 	struct klp_shadow *shadow;
 	unsigned long flags;
@@ -239,8 +274,7 @@ void klp_shadow_free(void *obj, unsigned long id)
 			       (unsigned long)obj) {
 
 		if (klp_shadow_match(shadow, obj, id)) {
-			hash_del_rcu(&shadow->node);
-			kfree_rcu(shadow, rcu_head);
+			klp_shadow_free_struct(shadow, dtor);
 			break;
 		}
 	}
@@ -252,11 +286,13 @@ EXPORT_SYMBOL_GPL(klp_shadow_free);
 /**
  * klp_shadow_free_all() - detach and free all <*, id> shadow variables
  * @id:		data identifier
+ * @dtor:	custom callback that can be used to unregister the variable
+ *		and/or free data that the shadow variable points to (optional)
  *
  * This function releases the memory for all <*, id> shadow variable
  * instances, callers should stop referencing them accordingly.
  */
-void klp_shadow_free_all(unsigned long id)
+void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
 {
 	struct klp_shadow *shadow;
 	unsigned long flags;
@@ -266,10 +302,8 @@ void klp_shadow_free_all(unsigned long id)
 
 	/* Delete all <*, id> from hash */
 	hash_for_each(klp_shadow_hash, i, shadow, node) {
-		if (klp_shadow_match(shadow, shadow->obj, id)) {
-			hash_del_rcu(&shadow->node);
-			kfree_rcu(shadow, rcu_head);
-		}
+		if (klp_shadow_match(shadow, shadow->obj, id))
+			klp_shadow_free_struct(shadow, dtor);
 	}
 
 	spin_unlock_irqrestore(&klp_shadow_lock, flags);
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 56add6327736..7c6631e693bc 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -33,6 +33,8 @@ struct klp_patch *klp_transition_patch;
 
 static int klp_target_state = KLP_UNDEFINED;
 
+static bool klp_forced = false;
+
 /*
  * This work can be performed periodically to finish patching or unpatching any
  * "straggler" tasks which failed to transition in the first attempt.
@@ -80,7 +82,6 @@ static void klp_complete_transition(void)
 	struct klp_func *func;
 	struct task_struct *g, *task;
 	unsigned int cpu;
-	bool immediate_func = false;
 
 	pr_debug("'%s': completing %s transition\n",
 		 klp_transition_patch->mod->name,
@@ -102,16 +103,9 @@ static void klp_complete_transition(void)
 		klp_synchronize_transition();
 	}
 
-	if (klp_transition_patch->immediate)
-		goto done;
-
-	klp_for_each_object(klp_transition_patch, obj) {
-		klp_for_each_func(obj, func) {
+	klp_for_each_object(klp_transition_patch, obj)
+		klp_for_each_func(obj, func)
 			func->transition = false;
-			if (func->immediate)
-				immediate_func = true;
-		}
-	}
 
 	/* Prevent klp_ftrace_handler() from seeing KLP_UNDEFINED state */
 	if (klp_target_state == KLP_PATCHED)
@@ -130,7 +124,6 @@ static void klp_complete_transition(void)
 		task->patch_state = KLP_UNDEFINED;
 	}
 
-done:
 	klp_for_each_object(klp_transition_patch, obj) {
 		if (!klp_is_object_loaded(obj))
 			continue;
@@ -144,13 +137,11 @@ done:
 		  klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
 
 	/*
-	 * See complementary comment in __klp_enable_patch() for why we
-	 * keep the module reference for immediate patches.
+	 * klp_forced set implies unbounded increase of module's ref count if
+	 * the module is disabled/enabled in a loop.
 	 */
-	if (!klp_transition_patch->immediate && !immediate_func &&
-	    klp_target_state == KLP_UNPATCHED) {
+	if (!klp_forced && klp_target_state == KLP_UNPATCHED)
 		module_put(klp_transition_patch->mod);
-	}
 
 	klp_target_state = KLP_UNDEFINED;
 	klp_transition_patch = NULL;
@@ -218,9 +209,6 @@ static int klp_check_stack_func(struct klp_func *func,
 	struct klp_ops *ops;
 	int i;
 
-	if (func->immediate)
-		return 0;
-
 	for (i = 0; i < trace->nr_entries; i++) {
 		address = trace->entries[i];
 
@@ -383,13 +371,6 @@ void klp_try_complete_transition(void)
 	WARN_ON_ONCE(klp_target_state == KLP_UNDEFINED);
 
 	/*
-	 * If the patch can be applied or reverted immediately, skip the
-	 * per-task transitions.
-	 */
-	if (klp_transition_patch->immediate)
-		goto success;
-
-	/*
 	 * Try to switch the tasks to the target patch state by walking their
 	 * stacks and looking for any to-be-patched or to-be-unpatched
 	 * functions.  If such functions are found on a stack, or if the stack
@@ -432,7 +413,6 @@ void klp_try_complete_transition(void)
 		return;
 	}
 
-success:
 	/* we're done, now cleanup the data structures */
 	klp_complete_transition();
 }
@@ -453,13 +433,6 @@ void klp_start_transition(void)
 		  klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
 
 	/*
-	 * If the patch can be applied or reverted immediately, skip the
-	 * per-task transitions.
-	 */
-	if (klp_transition_patch->immediate)
-		return;
-
-	/*
 	 * Mark all normal tasks as needing a patch state update.  They'll
 	 * switch either in klp_try_complete_transition() or as they exit the
 	 * kernel.
@@ -509,13 +482,6 @@ void klp_init_transition(struct klp_patch *patch, int state)
 		 klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
 
 	/*
-	 * If the patch can be applied or reverted immediately, skip the
-	 * per-task transitions.
-	 */
-	if (patch->immediate)
-		return;
-
-	/*
 	 * Initialize all tasks to the initial patch state to prepare them for
 	 * switching to the target state.
 	 */
@@ -608,3 +574,71 @@ void klp_copy_process(struct task_struct *child)
 
 	/* TIF_PATCH_PENDING gets copied in setup_thread_stack() */
 }
+
+/*
+ * Sends a fake signal to all non-kthread tasks with TIF_PATCH_PENDING set.
+ * Kthreads with TIF_PATCH_PENDING set are woken up. Only admin can request this
+ * action currently.
+ */
+void klp_send_signals(void)
+{
+	struct task_struct *g, *task;
+
+	pr_notice("signaling remaining tasks\n");
+
+	read_lock(&tasklist_lock);
+	for_each_process_thread(g, task) {
+		if (!klp_patch_pending(task))
+			continue;
+
+		/*
+		 * There is a small race here. We could see TIF_PATCH_PENDING
+		 * set and decide to wake up a kthread or send a fake signal.
+		 * Meanwhile the task could migrate itself and the action
+		 * would be meaningless. It is not serious though.
+		 */
+		if (task->flags & PF_KTHREAD) {
+			/*
+			 * Wake up a kthread which sleeps interruptedly and
+			 * still has not been migrated.
+			 */
+			wake_up_state(task, TASK_INTERRUPTIBLE);
+		} else {
+			/*
+			 * Send fake signal to all non-kthread tasks which are
+			 * still not migrated.
+			 */
+			spin_lock_irq(&task->sighand->siglock);
+			signal_wake_up(task, 0);
+			spin_unlock_irq(&task->sighand->siglock);
+		}
+	}
+	read_unlock(&tasklist_lock);
+}
+
+/*
+ * Drop TIF_PATCH_PENDING of all tasks on admin's request. This forces an
+ * existing transition to finish.
+ *
+ * NOTE: klp_update_patch_state(task) requires the task to be inactive or
+ * 'current'. This is not the case here and the consistency model could be
+ * broken. Administrator, who is the only one to execute the
+ * klp_force_transitions(), has to be aware of this.
+ */
+void klp_force_transition(void)
+{
+	struct task_struct *g, *task;
+	unsigned int cpu;
+
+	pr_warn("forcing remaining tasks to the patched state\n");
+
+	read_lock(&tasklist_lock);
+	for_each_process_thread(g, task)
+		klp_update_patch_state(task);
+	read_unlock(&tasklist_lock);
+
+	for_each_possible_cpu(cpu)
+		klp_update_patch_state(idle_task(cpu));
+
+	klp_forced = true;
+}
diff --git a/kernel/livepatch/transition.h b/kernel/livepatch/transition.h
index 0f6e27c481f9..f9d0bc016067 100644
--- a/kernel/livepatch/transition.h
+++ b/kernel/livepatch/transition.h
@@ -11,5 +11,7 @@ void klp_cancel_transition(void);
 void klp_start_transition(void);
 void klp_try_complete_transition(void);
 void klp_reverse_transition(void);
+void klp_send_signals(void);
+void klp_force_transition(void);
 
 #endif /* _LIVEPATCH_TRANSITION_H */