Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/livepatch/Kconfig b/kernel/livepatch/Kconfig
index ec45651..54102de 100644
--- a/kernel/livepatch/Kconfig
+++ b/kernel/livepatch/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
config HAVE_LIVEPATCH
bool
help
diff --git a/kernel/livepatch/Makefile b/kernel/livepatch/Makefile
index b36ceda..cf9b5bc 100644
--- a/kernel/livepatch/Makefile
+++ b/kernel/livepatch/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
obj-$(CONFIG_LIVEPATCH) += livepatch.o
livepatch-objs := core.o patch.o shadow.o transition.o
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 5b77a73..ab4a460 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -1,21 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
/*
* core.c - Kernel Live Patching Core
*
* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
* Copyright (C) 2014 SUSE
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -30,6 +18,7 @@
#include <linux/elf.h>
#include <linux/moduleloader.h>
#include <linux/completion.h>
+#include <linux/memory.h>
#include <asm/cacheflush.h>
#include "core.h"
#include "patch.h"
@@ -45,7 +34,12 @@
*/
DEFINE_MUTEX(klp_mutex);
-static LIST_HEAD(klp_patches);
+/*
+ * Actively used patches: enabled or in transition. Note that replaced
+ * or disabled patches are not listed even though the related kernel
+ * module still can be loaded.
+ */
+LIST_HEAD(klp_patches);
static struct kobject *klp_root_kobj;
@@ -82,22 +76,45 @@
mutex_unlock(&module_mutex);
}
-static bool klp_is_patch_registered(struct klp_patch *patch)
-{
- struct klp_patch *mypatch;
-
- list_for_each_entry(mypatch, &klp_patches, list)
- if (mypatch == patch)
- return true;
-
- return false;
-}
-
static bool klp_initialized(void)
{
return !!klp_root_kobj;
}
+static struct klp_func *klp_find_func(struct klp_object *obj,
+ struct klp_func *old_func)
+{
+ struct klp_func *func;
+
+ klp_for_each_func(obj, func) {
+ if ((strcmp(old_func->old_name, func->old_name) == 0) &&
+ (old_func->old_sympos == func->old_sympos)) {
+ return func;
+ }
+ }
+
+ return NULL;
+}
+
+static struct klp_object *klp_find_object(struct klp_patch *patch,
+ struct klp_object *old_obj)
+{
+ struct klp_object *obj;
+
+ klp_for_each_object(patch, obj) {
+ if (klp_is_module(old_obj)) {
+ if (klp_is_module(obj) &&
+ strcmp(old_obj->name, obj->name) == 0) {
+ return obj;
+ }
+ } else if (!klp_is_module(obj)) {
+ return obj;
+ }
+ }
+
+ return NULL;
+}
+
struct klp_find_arg {
const char *objname;
const char *name;
@@ -278,6 +295,580 @@
return ret;
}
+/*
+ * Sysfs Interface
+ *
+ * /sys/kernel/livepatch
+ * /sys/kernel/livepatch/<patch>
+ * /sys/kernel/livepatch/<patch>/enabled
+ * /sys/kernel/livepatch/<patch>/transition
+ * /sys/kernel/livepatch/<patch>/force
+ * /sys/kernel/livepatch/<patch>/<object>
+ * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
+ */
+static int __klp_disable_patch(struct klp_patch *patch);
+
+static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct klp_patch *patch;
+ int ret;
+ bool enabled;
+
+ ret = kstrtobool(buf, &enabled);
+ if (ret)
+ return ret;
+
+ patch = container_of(kobj, struct klp_patch, kobj);
+
+ mutex_lock(&klp_mutex);
+
+ if (patch->enabled == enabled) {
+ /* already in requested state */
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /*
+ * Allow to reverse a pending transition in both ways. It might be
+ * necessary to complete the transition without forcing and breaking
+ * the system integrity.
+ *
+ * Do not allow to re-enable a disabled patch.
+ */
+ if (patch == klp_transition_patch)
+ klp_reverse_transition();
+ else if (!enabled)
+ ret = __klp_disable_patch(patch);
+ else
+ ret = -EINVAL;
+
+out:
+ mutex_unlock(&klp_mutex);
+
+ if (ret)
+ return ret;
+ return count;
+}
+
+static ssize_t enabled_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct klp_patch *patch;
+
+ patch = container_of(kobj, struct klp_patch, kobj);
+ return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled);
+}
+
+static ssize_t transition_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct klp_patch *patch;
+
+ patch = container_of(kobj, struct klp_patch, kobj);
+ return snprintf(buf, PAGE_SIZE-1, "%d\n",
+ patch == klp_transition_patch);
+}
+
+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 force_kobj_attr = __ATTR_WO(force);
+static struct attribute *klp_patch_attrs[] = {
+ &enabled_kobj_attr.attr,
+ &transition_kobj_attr.attr,
+ &force_kobj_attr.attr,
+ NULL
+};
+ATTRIBUTE_GROUPS(klp_patch);
+
+static void klp_free_object_dynamic(struct klp_object *obj)
+{
+ kfree(obj->name);
+ kfree(obj);
+}
+
+static void klp_init_func_early(struct klp_object *obj,
+ struct klp_func *func);
+static void klp_init_object_early(struct klp_patch *patch,
+ struct klp_object *obj);
+
+static struct klp_object *klp_alloc_object_dynamic(const char *name,
+ struct klp_patch *patch)
+{
+ struct klp_object *obj;
+
+ obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+ if (!obj)
+ return NULL;
+
+ if (name) {
+ obj->name = kstrdup(name, GFP_KERNEL);
+ if (!obj->name) {
+ kfree(obj);
+ return NULL;
+ }
+ }
+
+ klp_init_object_early(patch, obj);
+ obj->dynamic = true;
+
+ return obj;
+}
+
+static void klp_free_func_nop(struct klp_func *func)
+{
+ kfree(func->old_name);
+ kfree(func);
+}
+
+static struct klp_func *klp_alloc_func_nop(struct klp_func *old_func,
+ struct klp_object *obj)
+{
+ struct klp_func *func;
+
+ func = kzalloc(sizeof(*func), GFP_KERNEL);
+ if (!func)
+ return NULL;
+
+ if (old_func->old_name) {
+ func->old_name = kstrdup(old_func->old_name, GFP_KERNEL);
+ if (!func->old_name) {
+ kfree(func);
+ return NULL;
+ }
+ }
+
+ klp_init_func_early(obj, func);
+ /*
+ * func->new_func is same as func->old_func. These addresses are
+ * set when the object is loaded, see klp_init_object_loaded().
+ */
+ func->old_sympos = old_func->old_sympos;
+ func->nop = true;
+
+ return func;
+}
+
+static int klp_add_object_nops(struct klp_patch *patch,
+ struct klp_object *old_obj)
+{
+ struct klp_object *obj;
+ struct klp_func *func, *old_func;
+
+ obj = klp_find_object(patch, old_obj);
+
+ if (!obj) {
+ obj = klp_alloc_object_dynamic(old_obj->name, patch);
+ if (!obj)
+ return -ENOMEM;
+ }
+
+ klp_for_each_func(old_obj, old_func) {
+ func = klp_find_func(obj, old_func);
+ if (func)
+ continue;
+
+ func = klp_alloc_func_nop(old_func, obj);
+ if (!func)
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+/*
+ * Add 'nop' functions which simply return to the caller to run
+ * the original function. The 'nop' functions are added to a
+ * patch to facilitate a 'replace' mode.
+ */
+static int klp_add_nops(struct klp_patch *patch)
+{
+ struct klp_patch *old_patch;
+ struct klp_object *old_obj;
+
+ klp_for_each_patch(old_patch) {
+ klp_for_each_object(old_patch, old_obj) {
+ int err;
+
+ err = klp_add_object_nops(patch, old_obj);
+ if (err)
+ return err;
+ }
+ }
+
+ return 0;
+}
+
+static void klp_kobj_release_patch(struct kobject *kobj)
+{
+ struct klp_patch *patch;
+
+ patch = container_of(kobj, struct klp_patch, kobj);
+ complete(&patch->finish);
+}
+
+static struct kobj_type klp_ktype_patch = {
+ .release = klp_kobj_release_patch,
+ .sysfs_ops = &kobj_sysfs_ops,
+ .default_groups = klp_patch_groups,
+};
+
+static void klp_kobj_release_object(struct kobject *kobj)
+{
+ struct klp_object *obj;
+
+ obj = container_of(kobj, struct klp_object, kobj);
+
+ if (obj->dynamic)
+ klp_free_object_dynamic(obj);
+}
+
+static struct kobj_type klp_ktype_object = {
+ .release = klp_kobj_release_object,
+ .sysfs_ops = &kobj_sysfs_ops,
+};
+
+static void klp_kobj_release_func(struct kobject *kobj)
+{
+ struct klp_func *func;
+
+ func = container_of(kobj, struct klp_func, kobj);
+
+ if (func->nop)
+ klp_free_func_nop(func);
+}
+
+static struct kobj_type klp_ktype_func = {
+ .release = klp_kobj_release_func,
+ .sysfs_ops = &kobj_sysfs_ops,
+};
+
+static void __klp_free_funcs(struct klp_object *obj, bool nops_only)
+{
+ struct klp_func *func, *tmp_func;
+
+ klp_for_each_func_safe(obj, func, tmp_func) {
+ if (nops_only && !func->nop)
+ continue;
+
+ list_del(&func->node);
+ kobject_put(&func->kobj);
+ }
+}
+
+/* Clean up when a patched object is unloaded */
+static void klp_free_object_loaded(struct klp_object *obj)
+{
+ struct klp_func *func;
+
+ obj->mod = NULL;
+
+ klp_for_each_func(obj, func) {
+ func->old_func = NULL;
+
+ if (func->nop)
+ func->new_func = NULL;
+ }
+}
+
+static void __klp_free_objects(struct klp_patch *patch, bool nops_only)
+{
+ struct klp_object *obj, *tmp_obj;
+
+ klp_for_each_object_safe(patch, obj, tmp_obj) {
+ __klp_free_funcs(obj, nops_only);
+
+ if (nops_only && !obj->dynamic)
+ continue;
+
+ list_del(&obj->node);
+ kobject_put(&obj->kobj);
+ }
+}
+
+static void klp_free_objects(struct klp_patch *patch)
+{
+ __klp_free_objects(patch, false);
+}
+
+static void klp_free_objects_dynamic(struct klp_patch *patch)
+{
+ __klp_free_objects(patch, true);
+}
+
+/*
+ * This function implements the free operations that can be called safely
+ * under klp_mutex.
+ *
+ * The operation must be completed by calling klp_free_patch_finish()
+ * outside klp_mutex.
+ */
+void klp_free_patch_start(struct klp_patch *patch)
+{
+ if (!list_empty(&patch->list))
+ list_del(&patch->list);
+
+ klp_free_objects(patch);
+}
+
+/*
+ * This function implements the free part that must be called outside
+ * klp_mutex.
+ *
+ * It must be called after klp_free_patch_start(). And it has to be
+ * the last function accessing the livepatch structures when the patch
+ * gets disabled.
+ */
+static void klp_free_patch_finish(struct klp_patch *patch)
+{
+ /*
+ * Avoid deadlock with enabled_store() sysfs callback by
+ * calling this outside klp_mutex. It is safe because
+ * this is called when the patch gets disabled and it
+ * cannot get enabled again.
+ */
+ kobject_put(&patch->kobj);
+ wait_for_completion(&patch->finish);
+
+ /* Put the module after the last access to struct klp_patch. */
+ if (!patch->forced)
+ module_put(patch->mod);
+}
+
+/*
+ * The livepatch might be freed from sysfs interface created by the patch.
+ * This work allows to wait until the interface is destroyed in a separate
+ * context.
+ */
+static void klp_free_patch_work_fn(struct work_struct *work)
+{
+ struct klp_patch *patch =
+ container_of(work, struct klp_patch, free_work);
+
+ klp_free_patch_finish(patch);
+}
+
+static int klp_init_func(struct klp_object *obj, struct klp_func *func)
+{
+ if (!func->old_name)
+ return -EINVAL;
+
+ /*
+ * NOPs get the address later. The patched module must be loaded,
+ * see klp_init_object_loaded().
+ */
+ if (!func->new_func && !func->nop)
+ return -EINVAL;
+
+ if (strlen(func->old_name) >= KSYM_NAME_LEN)
+ return -EINVAL;
+
+ INIT_LIST_HEAD(&func->stack_node);
+ func->patched = false;
+ func->transition = false;
+
+ /* The format for the sysfs directory is <function,sympos> where sympos
+ * is the nth occurrence of this symbol in kallsyms for the patched
+ * object. If the user selects 0 for old_sympos, then 1 will be used
+ * since a unique symbol will be the first occurrence.
+ */
+ return kobject_add(&func->kobj, &obj->kobj, "%s,%lu",
+ func->old_name,
+ func->old_sympos ? func->old_sympos : 1);
+}
+
+/* Arches may override this to finish any remaining arch-specific tasks */
+void __weak arch_klp_init_object_loaded(struct klp_patch *patch,
+ struct klp_object *obj)
+{
+}
+
+/* parts of the initialization that is done only when the object is loaded */
+static int klp_init_object_loaded(struct klp_patch *patch,
+ struct klp_object *obj)
+{
+ struct klp_func *func;
+ int ret;
+
+ mutex_lock(&text_mutex);
+
+ module_disable_ro(patch->mod);
+ ret = klp_write_object_relocations(patch->mod, obj);
+ if (ret) {
+ module_enable_ro(patch->mod, true);
+ mutex_unlock(&text_mutex);
+ return ret;
+ }
+
+ arch_klp_init_object_loaded(patch, obj);
+ module_enable_ro(patch->mod, true);
+
+ mutex_unlock(&text_mutex);
+
+ klp_for_each_func(obj, func) {
+ ret = klp_find_object_symbol(obj->name, func->old_name,
+ func->old_sympos,
+ (unsigned long *)&func->old_func);
+ if (ret)
+ return ret;
+
+ ret = kallsyms_lookup_size_offset((unsigned long)func->old_func,
+ &func->old_size, NULL);
+ if (!ret) {
+ pr_err("kallsyms size lookup failed for '%s'\n",
+ func->old_name);
+ return -ENOENT;
+ }
+
+ if (func->nop)
+ func->new_func = func->old_func;
+
+ ret = kallsyms_lookup_size_offset((unsigned long)func->new_func,
+ &func->new_size, NULL);
+ if (!ret) {
+ pr_err("kallsyms size lookup failed for '%s' replacement\n",
+ func->old_name);
+ return -ENOENT;
+ }
+ }
+
+ return 0;
+}
+
+static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
+{
+ struct klp_func *func;
+ int ret;
+ const char *name;
+
+ if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN)
+ return -EINVAL;
+
+ obj->patched = false;
+ obj->mod = NULL;
+
+ klp_find_object_module(obj);
+
+ name = klp_is_module(obj) ? obj->name : "vmlinux";
+ ret = kobject_add(&obj->kobj, &patch->kobj, "%s", name);
+ if (ret)
+ return ret;
+
+ klp_for_each_func(obj, func) {
+ ret = klp_init_func(obj, func);
+ if (ret)
+ return ret;
+ }
+
+ if (klp_is_object_loaded(obj))
+ ret = klp_init_object_loaded(patch, obj);
+
+ return ret;
+}
+
+static void klp_init_func_early(struct klp_object *obj,
+ struct klp_func *func)
+{
+ kobject_init(&func->kobj, &klp_ktype_func);
+ list_add_tail(&func->node, &obj->func_list);
+}
+
+static void klp_init_object_early(struct klp_patch *patch,
+ struct klp_object *obj)
+{
+ INIT_LIST_HEAD(&obj->func_list);
+ kobject_init(&obj->kobj, &klp_ktype_object);
+ list_add_tail(&obj->node, &patch->obj_list);
+}
+
+static int klp_init_patch_early(struct klp_patch *patch)
+{
+ struct klp_object *obj;
+ struct klp_func *func;
+
+ if (!patch->objs)
+ return -EINVAL;
+
+ INIT_LIST_HEAD(&patch->list);
+ INIT_LIST_HEAD(&patch->obj_list);
+ kobject_init(&patch->kobj, &klp_ktype_patch);
+ patch->enabled = false;
+ patch->forced = false;
+ INIT_WORK(&patch->free_work, klp_free_patch_work_fn);
+ init_completion(&patch->finish);
+
+ klp_for_each_object_static(patch, obj) {
+ if (!obj->funcs)
+ return -EINVAL;
+
+ klp_init_object_early(patch, obj);
+
+ klp_for_each_func_static(obj, func) {
+ klp_init_func_early(obj, func);
+ }
+ }
+
+ if (!try_module_get(patch->mod))
+ return -ENODEV;
+
+ return 0;
+}
+
+static int klp_init_patch(struct klp_patch *patch)
+{
+ struct klp_object *obj;
+ int ret;
+
+ ret = kobject_add(&patch->kobj, klp_root_kobj, "%s", patch->mod->name);
+ if (ret)
+ return ret;
+
+ if (patch->replace) {
+ ret = klp_add_nops(patch);
+ if (ret)
+ return ret;
+ }
+
+ klp_for_each_object(patch, obj) {
+ ret = klp_init_object(patch, obj);
+ if (ret)
+ return ret;
+ }
+
+ list_add_tail(&patch->list, &klp_patches);
+
+ return 0;
+}
+
static int __klp_disable_patch(struct klp_patch *patch)
{
struct klp_object *obj;
@@ -288,11 +879,6 @@
if (klp_transition_patch)
return -EBUSY;
- /* enforce stacking: only the last enabled patch can be disabled */
- if (!list_is_last(&patch->list, &klp_patches) &&
- list_next_entry(patch, list)->enabled)
- return -EBUSY;
-
klp_init_transition(patch, KLP_UNPATCHED);
klp_for_each_object(patch, obj)
@@ -309,44 +895,12 @@
smp_wmb();
klp_start_transition();
- klp_try_complete_transition();
patch->enabled = false;
+ klp_try_complete_transition();
return 0;
}
-/**
- * klp_disable_patch() - disables a registered patch
- * @patch: The registered, enabled patch to be disabled
- *
- * Unregisters the patched functions from ftrace.
- *
- * Return: 0 on success, otherwise error
- */
-int klp_disable_patch(struct klp_patch *patch)
-{
- int ret;
-
- mutex_lock(&klp_mutex);
-
- if (!klp_is_patch_registered(patch)) {
- ret = -EINVAL;
- goto err;
- }
-
- if (!patch->enabled) {
- ret = -EINVAL;
- goto err;
- }
-
- ret = __klp_disable_patch(patch);
-
-err:
- mutex_unlock(&klp_mutex);
- return ret;
-}
-EXPORT_SYMBOL_GPL(klp_disable_patch);
-
static int __klp_enable_patch(struct klp_patch *patch)
{
struct klp_object *obj;
@@ -358,18 +912,6 @@
if (WARN_ON(patch->enabled))
return -EINVAL;
- /* enforce stacking: only the first disabled patch can be enabled */
- if (patch->list.prev != &klp_patches &&
- !list_prev_entry(patch, list)->enabled)
- return -EBUSY;
-
- /*
- * A reference is taken on the patch module to prevent it from being
- * unloaded.
- */
- if (!try_module_get(patch->mod))
- return -ENODEV;
-
pr_notice("enabling patch '%s'\n", patch->mod->name);
klp_init_transition(patch, KLP_PATCHED);
@@ -403,8 +945,8 @@
}
klp_start_transition();
- klp_try_complete_transition();
patch->enabled = true;
+ klp_try_complete_transition();
return 0;
err:
@@ -415,11 +957,15 @@
}
/**
- * klp_enable_patch() - enables a registered patch
- * @patch: The registered, disabled patch to be enabled
+ * klp_enable_patch() - enable the livepatch
+ * @patch: patch to be enabled
*
- * Performs the needed symbol lookups and code relocations,
- * then registers the patched functions with ftrace.
+ * Initializes the data structure associated with the patch, creates the sysfs
+ * interface, performs the needed symbol lookups and code relocations,
+ * registers the patched functions with ftrace.
+ *
+ * This function is supposed to be called from the livepatch module_init()
+ * callback.
*
* Return: 0 on success, otherwise error
*/
@@ -427,462 +973,6 @@
{
int ret;
- mutex_lock(&klp_mutex);
-
- if (!klp_is_patch_registered(patch)) {
- ret = -EINVAL;
- goto err;
- }
-
- ret = __klp_enable_patch(patch);
-
-err:
- mutex_unlock(&klp_mutex);
- return ret;
-}
-EXPORT_SYMBOL_GPL(klp_enable_patch);
-
-/*
- * Sysfs Interface
- *
- * /sys/kernel/livepatch
- * /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>
- */
-
-static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
- const char *buf, size_t count)
-{
- struct klp_patch *patch;
- int ret;
- bool enabled;
-
- ret = kstrtobool(buf, &enabled);
- if (ret)
- return ret;
-
- patch = container_of(kobj, struct klp_patch, kobj);
-
- mutex_lock(&klp_mutex);
-
- if (!klp_is_patch_registered(patch)) {
- /*
- * Module with the patch could either disappear meanwhile or is
- * not properly initialized yet.
- */
- ret = -EINVAL;
- goto err;
- }
-
- if (patch->enabled == enabled) {
- /* already in requested state */
- ret = -EINVAL;
- goto err;
- }
-
- if (patch == klp_transition_patch) {
- klp_reverse_transition();
- } else if (enabled) {
- ret = __klp_enable_patch(patch);
- if (ret)
- goto err;
- } else {
- ret = __klp_disable_patch(patch);
- if (ret)
- goto err;
- }
-
- mutex_unlock(&klp_mutex);
-
- return count;
-
-err:
- mutex_unlock(&klp_mutex);
- return ret;
-}
-
-static ssize_t enabled_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- struct klp_patch *patch;
-
- patch = container_of(kobj, struct klp_patch, kobj);
- return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled);
-}
-
-static ssize_t transition_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- struct klp_patch *patch;
-
- patch = container_of(kobj, struct klp_patch, kobj);
- return snprintf(buf, PAGE_SIZE-1, "%d\n",
- 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
-};
-
-static void klp_kobj_release_patch(struct kobject *kobj)
-{
- struct klp_patch *patch;
-
- patch = container_of(kobj, struct klp_patch, kobj);
- complete(&patch->finish);
-}
-
-static struct kobj_type klp_ktype_patch = {
- .release = klp_kobj_release_patch,
- .sysfs_ops = &kobj_sysfs_ops,
- .default_attrs = klp_patch_attrs,
-};
-
-static void klp_kobj_release_object(struct kobject *kobj)
-{
-}
-
-static struct kobj_type klp_ktype_object = {
- .release = klp_kobj_release_object,
- .sysfs_ops = &kobj_sysfs_ops,
-};
-
-static void klp_kobj_release_func(struct kobject *kobj)
-{
-}
-
-static struct kobj_type klp_ktype_func = {
- .release = klp_kobj_release_func,
- .sysfs_ops = &kobj_sysfs_ops,
-};
-
-/*
- * Free all functions' kobjects in the array up to some limit. When limit is
- * NULL, all kobjects are freed.
- */
-static void klp_free_funcs_limited(struct klp_object *obj,
- struct klp_func *limit)
-{
- struct klp_func *func;
-
- for (func = obj->funcs; func->old_name && func != limit; func++)
- kobject_put(&func->kobj);
-}
-
-/* Clean up when a patched object is unloaded */
-static void klp_free_object_loaded(struct klp_object *obj)
-{
- struct klp_func *func;
-
- obj->mod = NULL;
-
- klp_for_each_func(obj, func)
- func->old_addr = 0;
-}
-
-/*
- * Free all objects' kobjects in the array up to some limit. When limit is
- * NULL, all kobjects are freed.
- */
-static void klp_free_objects_limited(struct klp_patch *patch,
- struct klp_object *limit)
-{
- struct klp_object *obj;
-
- for (obj = patch->objs; obj->funcs && obj != limit; obj++) {
- klp_free_funcs_limited(obj, NULL);
- kobject_put(&obj->kobj);
- }
-}
-
-static void klp_free_patch(struct klp_patch *patch)
-{
- klp_free_objects_limited(patch, NULL);
- if (!list_empty(&patch->list))
- list_del(&patch->list);
-}
-
-static int klp_init_func(struct klp_object *obj, struct klp_func *func)
-{
- if (!func->old_name || !func->new_func)
- return -EINVAL;
-
- if (strlen(func->old_name) >= KSYM_NAME_LEN)
- return -EINVAL;
-
- INIT_LIST_HEAD(&func->stack_node);
- func->patched = false;
- func->transition = false;
-
- /* The format for the sysfs directory is <function,sympos> where sympos
- * is the nth occurrence of this symbol in kallsyms for the patched
- * object. If the user selects 0 for old_sympos, then 1 will be used
- * since a unique symbol will be the first occurrence.
- */
- return kobject_init_and_add(&func->kobj, &klp_ktype_func,
- &obj->kobj, "%s,%lu", func->old_name,
- func->old_sympos ? func->old_sympos : 1);
-}
-
-/* Arches may override this to finish any remaining arch-specific tasks */
-void __weak arch_klp_init_object_loaded(struct klp_patch *patch,
- struct klp_object *obj)
-{
-}
-
-/* parts of the initialization that is done only when the object is loaded */
-static int klp_init_object_loaded(struct klp_patch *patch,
- struct klp_object *obj)
-{
- struct klp_func *func;
- int ret;
-
- module_disable_ro(patch->mod);
- ret = klp_write_object_relocations(patch->mod, obj);
- if (ret) {
- module_enable_ro(patch->mod, true);
- return ret;
- }
-
- arch_klp_init_object_loaded(patch, obj);
- module_enable_ro(patch->mod, true);
-
- klp_for_each_func(obj, func) {
- ret = klp_find_object_symbol(obj->name, func->old_name,
- func->old_sympos,
- &func->old_addr);
- if (ret)
- return ret;
-
- ret = kallsyms_lookup_size_offset(func->old_addr,
- &func->old_size, NULL);
- if (!ret) {
- pr_err("kallsyms size lookup failed for '%s'\n",
- func->old_name);
- return -ENOENT;
- }
-
- ret = kallsyms_lookup_size_offset((unsigned long)func->new_func,
- &func->new_size, NULL);
- if (!ret) {
- pr_err("kallsyms size lookup failed for '%s' replacement\n",
- func->old_name);
- return -ENOENT;
- }
- }
-
- return 0;
-}
-
-static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
-{
- struct klp_func *func;
- int ret;
- const char *name;
-
- if (!obj->funcs)
- return -EINVAL;
-
- if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN)
- return -EINVAL;
-
- obj->patched = false;
- obj->mod = NULL;
-
- klp_find_object_module(obj);
-
- name = klp_is_module(obj) ? obj->name : "vmlinux";
- ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object,
- &patch->kobj, "%s", name);
- if (ret)
- return ret;
-
- klp_for_each_func(obj, func) {
- ret = klp_init_func(obj, func);
- if (ret)
- goto free;
- }
-
- if (klp_is_object_loaded(obj)) {
- ret = klp_init_object_loaded(patch, obj);
- if (ret)
- goto free;
- }
-
- return 0;
-
-free:
- klp_free_funcs_limited(obj, func);
- kobject_put(&obj->kobj);
- return ret;
-}
-
-static int klp_init_patch(struct klp_patch *patch)
-{
- struct klp_object *obj;
- int ret;
-
- if (!patch->objs)
- return -EINVAL;
-
- mutex_lock(&klp_mutex);
-
- patch->enabled = false;
- init_completion(&patch->finish);
-
- ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch,
- klp_root_kobj, "%s", patch->mod->name);
- if (ret) {
- mutex_unlock(&klp_mutex);
- return ret;
- }
-
- klp_for_each_object(patch, obj) {
- ret = klp_init_object(patch, obj);
- if (ret)
- goto free;
- }
-
- list_add_tail(&patch->list, &klp_patches);
-
- mutex_unlock(&klp_mutex);
-
- return 0;
-
-free:
- klp_free_objects_limited(patch, obj);
-
- mutex_unlock(&klp_mutex);
-
- kobject_put(&patch->kobj);
- wait_for_completion(&patch->finish);
-
- return ret;
-}
-
-/**
- * klp_unregister_patch() - unregisters a patch
- * @patch: Disabled patch to be unregistered
- *
- * Frees the data structures and removes the sysfs interface.
- *
- * Return: 0 on success, otherwise error
- */
-int klp_unregister_patch(struct klp_patch *patch)
-{
- int ret;
-
- mutex_lock(&klp_mutex);
-
- if (!klp_is_patch_registered(patch)) {
- ret = -EINVAL;
- goto err;
- }
-
- if (patch->enabled) {
- ret = -EBUSY;
- goto err;
- }
-
- klp_free_patch(patch);
-
- mutex_unlock(&klp_mutex);
-
- kobject_put(&patch->kobj);
- wait_for_completion(&patch->finish);
-
- return 0;
-err:
- mutex_unlock(&klp_mutex);
- return ret;
-}
-EXPORT_SYMBOL_GPL(klp_unregister_patch);
-
-/**
- * klp_register_patch() - registers a patch
- * @patch: Patch to be registered
- *
- * Initializes the data structure associated with the patch and
- * creates the sysfs interface.
- *
- * There is no need to take the reference on the patch module here. It is done
- * later when the patch is enabled.
- *
- * Return: 0 on success, otherwise error
- */
-int klp_register_patch(struct klp_patch *patch)
-{
if (!patch || !patch->mod)
return -EINVAL;
@@ -896,13 +986,91 @@
return -ENODEV;
if (!klp_have_reliable_stack()) {
- pr_err("This architecture doesn't have support for the livepatch consistency model.\n");
- return -ENOSYS;
+ pr_warn("This architecture doesn't have support for the livepatch consistency model.\n");
+ pr_warn("The livepatch transition may never complete.\n");
}
- return klp_init_patch(patch);
+ mutex_lock(&klp_mutex);
+
+ ret = klp_init_patch_early(patch);
+ if (ret) {
+ mutex_unlock(&klp_mutex);
+ return ret;
+ }
+
+ ret = klp_init_patch(patch);
+ if (ret)
+ goto err;
+
+ ret = __klp_enable_patch(patch);
+ if (ret)
+ goto err;
+
+ mutex_unlock(&klp_mutex);
+
+ return 0;
+
+err:
+ klp_free_patch_start(patch);
+
+ mutex_unlock(&klp_mutex);
+
+ klp_free_patch_finish(patch);
+
+ return ret;
}
-EXPORT_SYMBOL_GPL(klp_register_patch);
+EXPORT_SYMBOL_GPL(klp_enable_patch);
+
+/*
+ * This function removes replaced patches.
+ *
+ * We could be pretty aggressive here. It is called in the situation where
+ * these structures are no longer accessible. All functions are redirected
+ * by the klp_transition_patch. They use either a new code or they are in
+ * the original code because of the special nop function patches.
+ *
+ * The only exception is when the transition was forced. In this case,
+ * klp_ftrace_handler() might still see the replaced patch on the stack.
+ * Fortunately, it is carefully designed to work with removed functions
+ * thanks to RCU. We only have to keep the patches on the system. Also
+ * this is handled transparently by patch->module_put.
+ */
+void klp_discard_replaced_patches(struct klp_patch *new_patch)
+{
+ struct klp_patch *old_patch, *tmp_patch;
+
+ klp_for_each_patch_safe(old_patch, tmp_patch) {
+ if (old_patch == new_patch)
+ return;
+
+ old_patch->enabled = false;
+ klp_unpatch_objects(old_patch);
+ klp_free_patch_start(old_patch);
+ schedule_work(&old_patch->free_work);
+ }
+}
+
+/*
+ * This function removes the dynamically allocated 'nop' functions.
+ *
+ * We could be pretty aggressive. NOPs do not change the existing
+ * behavior except for adding unnecessary delay by the ftrace handler.
+ *
+ * It is safe even when the transition was forced. The ftrace handler
+ * will see a valid ops->func_stack entry thanks to RCU.
+ *
+ * We could even free the NOPs structures. They must be the last entry
+ * in ops->func_stack. Therefore unregister_ftrace_function() is called.
+ * It does the same as klp_synchronize_transition() to make sure that
+ * nobody is inside the ftrace handler once the operation finishes.
+ *
+ * IMPORTANT: It must be called right after removing the replaced patches!
+ */
+void klp_discard_nops(struct klp_patch *new_patch)
+{
+ klp_unpatch_objects_dynamic(klp_transition_patch);
+ klp_free_objects_dynamic(klp_transition_patch);
+}
/*
* Remove parts of patches that touch a given kernel module. The list of
@@ -915,7 +1083,7 @@
struct klp_patch *patch;
struct klp_object *obj;
- list_for_each_entry(patch, &klp_patches, list) {
+ klp_for_each_patch(patch) {
if (patch == limit)
break;
@@ -923,21 +1091,14 @@
if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
continue;
- /*
- * Only unpatch the module if the patch is enabled or
- * is in transition.
- */
- if (patch->enabled || patch == klp_transition_patch) {
+ if (patch != klp_transition_patch)
+ klp_pre_unpatch_callback(obj);
- if (patch != klp_transition_patch)
- klp_pre_unpatch_callback(obj);
+ pr_notice("reverting patch '%s' on unloading module '%s'\n",
+ patch->mod->name, obj->mod->name);
+ klp_unpatch_object(obj);
- pr_notice("reverting patch '%s' on unloading module '%s'\n",
- patch->mod->name, obj->mod->name);
- klp_unpatch_object(obj);
-
- klp_post_unpatch_callback(obj);
- }
+ klp_post_unpatch_callback(obj);
klp_free_object_loaded(obj);
break;
@@ -962,7 +1123,7 @@
*/
mod->klp_alive = true;
- list_for_each_entry(patch, &klp_patches, list) {
+ klp_for_each_patch(patch) {
klp_for_each_object(patch, obj) {
if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
continue;
@@ -976,13 +1137,6 @@
goto err;
}
- /*
- * Only patch the module if the patch is enabled or is
- * in transition.
- */
- if (!patch->enabled && patch != klp_transition_patch)
- break;
-
pr_notice("applying patch '%s' to loading module '%s'\n",
patch->mod->name, obj->mod->name);
@@ -1021,6 +1175,7 @@
pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
patch->mod->name, obj->mod->name, obj->mod->name);
mod->klp_alive = false;
+ obj->mod = NULL;
klp_cleanup_module_patches_limited(mod, patch);
mutex_unlock(&klp_mutex);
@@ -1048,14 +1203,6 @@
static int __init klp_init(void)
{
- int ret;
-
- ret = klp_check_compiler_support();
- if (ret) {
- pr_info("Your compiler is too old; turning off.\n");
- return -EINVAL;
- }
-
klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj);
if (!klp_root_kobj)
return -ENOMEM;
diff --git a/kernel/livepatch/core.h b/kernel/livepatch/core.h
index 48a83d4..ec43a40 100644
--- a/kernel/livepatch/core.h
+++ b/kernel/livepatch/core.h
@@ -5,6 +5,17 @@
#include <linux/livepatch.h>
extern struct mutex klp_mutex;
+extern struct list_head klp_patches;
+
+#define klp_for_each_patch_safe(patch, tmp_patch) \
+ list_for_each_entry_safe(patch, tmp_patch, &klp_patches, list)
+
+#define klp_for_each_patch(patch) \
+ list_for_each_entry(patch, &klp_patches, list)
+
+void klp_free_patch_start(struct klp_patch *patch);
+void klp_discard_replaced_patches(struct klp_patch *new_patch);
+void klp_discard_nops(struct klp_patch *new_patch);
static inline bool klp_is_object_loaded(struct klp_object *obj)
{
diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
index 82d5842..bd43537 100644
--- a/kernel/livepatch/patch.c
+++ b/kernel/livepatch/patch.c
@@ -1,22 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
/*
* patch.c - livepatch patching functions
*
* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
* Copyright (C) 2014 SUSE
* Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -34,7 +22,7 @@
static LIST_HEAD(klp_ops);
-struct klp_ops *klp_find_ops(unsigned long old_addr)
+struct klp_ops *klp_find_ops(void *old_func)
{
struct klp_ops *ops;
struct klp_func *func;
@@ -42,7 +30,7 @@
list_for_each_entry(ops, &klp_ops, node) {
func = list_first_entry(&ops->func_stack, struct klp_func,
stack_node);
- if (func->old_addr == old_addr)
+ if (func->old_func == old_func)
return ops;
}
@@ -61,7 +49,7 @@
ops = container_of(fops, struct klp_ops, fops);
/*
- * A variant of synchronize_sched() is used to allow patching functions
+ * A variant of synchronize_rcu() is used to allow patching functions
* where RCU is not watching, see klp_synchronize_transition().
*/
preempt_disable_notrace();
@@ -72,7 +60,7 @@
/*
* func should never be NULL because preemption should be disabled here
* and unregister_ftrace_function() does the equivalent of a
- * synchronize_sched() before the func_stack removal.
+ * synchronize_rcu() before the func_stack removal.
*/
if (WARN_ON_ONCE(!func))
goto unlock;
@@ -118,7 +106,15 @@
}
}
+ /*
+ * NOPs are used to replace existing patches with original code.
+ * Do nothing! Setting pc would cause an infinite loop.
+ */
+ if (func->nop)
+ goto unlock;
+
klp_arch_set_pc(regs, (unsigned long)func->new_func);
+
unlock:
preempt_enable_notrace();
}
@@ -142,17 +138,18 @@
if (WARN_ON(!func->patched))
return;
- if (WARN_ON(!func->old_addr))
+ if (WARN_ON(!func->old_func))
return;
- ops = klp_find_ops(func->old_addr);
+ ops = klp_find_ops(func->old_func);
if (WARN_ON(!ops))
return;
if (list_is_singular(&ops->func_stack)) {
unsigned long ftrace_loc;
- ftrace_loc = klp_get_ftrace_location(func->old_addr);
+ ftrace_loc =
+ klp_get_ftrace_location((unsigned long)func->old_func);
if (WARN_ON(!ftrace_loc))
return;
@@ -174,17 +171,18 @@
struct klp_ops *ops;
int ret;
- if (WARN_ON(!func->old_addr))
+ if (WARN_ON(!func->old_func))
return -EINVAL;
if (WARN_ON(func->patched))
return -EINVAL;
- ops = klp_find_ops(func->old_addr);
+ ops = klp_find_ops(func->old_func);
if (!ops) {
unsigned long ftrace_loc;
- ftrace_loc = klp_get_ftrace_location(func->old_addr);
+ ftrace_loc =
+ klp_get_ftrace_location((unsigned long)func->old_func);
if (!ftrace_loc) {
pr_err("failed to find location for function '%s'\n",
func->old_name);
@@ -236,15 +234,26 @@
return ret;
}
-void klp_unpatch_object(struct klp_object *obj)
+static void __klp_unpatch_object(struct klp_object *obj, bool nops_only)
{
struct klp_func *func;
- klp_for_each_func(obj, func)
+ klp_for_each_func(obj, func) {
+ if (nops_only && !func->nop)
+ continue;
+
if (func->patched)
klp_unpatch_func(func);
+ }
- obj->patched = false;
+ if (obj->dynamic || !nops_only)
+ obj->patched = false;
+}
+
+
+void klp_unpatch_object(struct klp_object *obj)
+{
+ __klp_unpatch_object(obj, false);
}
int klp_patch_object(struct klp_object *obj)
@@ -267,11 +276,21 @@
return 0;
}
-void klp_unpatch_objects(struct klp_patch *patch)
+static void __klp_unpatch_objects(struct klp_patch *patch, bool nops_only)
{
struct klp_object *obj;
klp_for_each_object(patch, obj)
if (obj->patched)
- klp_unpatch_object(obj);
+ __klp_unpatch_object(obj, nops_only);
+}
+
+void klp_unpatch_objects(struct klp_patch *patch)
+{
+ __klp_unpatch_objects(patch, false);
+}
+
+void klp_unpatch_objects_dynamic(struct klp_patch *patch)
+{
+ __klp_unpatch_objects(patch, true);
}
diff --git a/kernel/livepatch/patch.h b/kernel/livepatch/patch.h
index e72d825..d5f2fbe 100644
--- a/kernel/livepatch/patch.h
+++ b/kernel/livepatch/patch.h
@@ -10,7 +10,7 @@
* struct klp_ops - structure for tracking registered ftrace ops structs
*
* A single ftrace_ops is shared between all enabled replacement functions
- * (klp_func structs) which have the same old_addr. This allows the switch
+ * (klp_func structs) which have the same old_func. This allows the switch
* between function versions to happen instantaneously by updating the klp_ops
* struct's func_stack list. The winner is the klp_func at the top of the
* func_stack (front of the list).
@@ -25,10 +25,11 @@
struct ftrace_ops fops;
};
-struct klp_ops *klp_find_ops(unsigned long old_addr);
+struct klp_ops *klp_find_ops(void *old_func);
int klp_patch_object(struct klp_object *obj);
void klp_unpatch_object(struct klp_object *obj);
void klp_unpatch_objects(struct klp_patch *patch);
+void klp_unpatch_objects_dynamic(struct klp_patch *patch);
#endif /* _LIVEPATCH_PATCH_H */
diff --git a/kernel/livepatch/shadow.c b/kernel/livepatch/shadow.c
index 83958c8..e5c9fb2 100644
--- a/kernel/livepatch/shadow.c
+++ b/kernel/livepatch/shadow.c
@@ -1,22 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
/*
* shadow.c - Shadow Variables
*
* Copyright (C) 2014 Josh Poimboeuf <jpoimboe@redhat.com>
* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
* Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
/**
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 5bc3498..cdf318d 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -1,20 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
/*
* transition.c - Kernel Live Patching transition functions
*
* Copyright (C) 2015-2016 Josh Poimboeuf <jpoimboe@redhat.com>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -29,11 +17,13 @@
#define MAX_STACK_ENTRIES 100
#define STACK_ERR_BUF_SIZE 128
+#define SIGNALS_TIMEOUT 15
+
struct klp_patch *klp_transition_patch;
static int klp_target_state = KLP_UNDEFINED;
-static bool klp_forced = false;
+static unsigned int klp_signals_cnt;
/*
* This work can be performed periodically to finish patching or unpatching any
@@ -52,7 +42,7 @@
/*
* This function is just a stub to implement a hard force
- * of synchronize_sched(). This requires synchronizing
+ * of synchronize_rcu(). This requires synchronizing
* tasks even in userspace and idle.
*/
static void klp_sync(struct work_struct *work)
@@ -87,6 +77,11 @@
klp_transition_patch->mod->name,
klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
+ if (klp_transition_patch->replace && klp_target_state == KLP_PATCHED) {
+ klp_discard_replaced_patches(klp_transition_patch);
+ klp_discard_nops(klp_transition_patch);
+ }
+
if (klp_target_state == KLP_UNPATCHED) {
/*
* All tasks have transitioned to KLP_UNPATCHED so we can now
@@ -136,13 +131,6 @@
pr_notice("'%s': %s complete\n", klp_transition_patch->mod->name,
klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
- /*
- * klp_forced set implies unbounded increase of module's ref count if
- * the module is disabled/enabled in a loop.
- */
- if (!klp_forced && klp_target_state == KLP_UNPATCHED)
- module_put(klp_transition_patch->mod);
-
klp_target_state = KLP_UNDEFINED;
klp_transition_patch = NULL;
}
@@ -175,7 +163,7 @@
void klp_update_patch_state(struct task_struct *task)
{
/*
- * A variant of synchronize_sched() is used to allow patching functions
+ * A variant of synchronize_rcu() is used to allow patching functions
* where RCU is not watching, see klp_synchronize_transition().
*/
preempt_disable_notrace();
@@ -202,15 +190,15 @@
* Determine whether the given stack trace includes any references to a
* to-be-patched or to-be-unpatched function.
*/
-static int klp_check_stack_func(struct klp_func *func,
- struct stack_trace *trace)
+static int klp_check_stack_func(struct klp_func *func, unsigned long *entries,
+ unsigned int nr_entries)
{
unsigned long func_addr, func_size, address;
struct klp_ops *ops;
int i;
- for (i = 0; i < trace->nr_entries; i++) {
- address = trace->entries[i];
+ for (i = 0; i < nr_entries; i++) {
+ address = entries[i];
if (klp_target_state == KLP_UNPATCHED) {
/*
@@ -224,11 +212,11 @@
* Check for the to-be-patched function
* (the previous func).
*/
- ops = klp_find_ops(func->old_addr);
+ ops = klp_find_ops(func->old_func);
if (list_is_singular(&ops->func_stack)) {
/* original function */
- func_addr = func->old_addr;
+ func_addr = (unsigned long)func->old_func;
func_size = func->old_size;
} else {
/* previously patched function */
@@ -254,29 +242,24 @@
static int klp_check_stack(struct task_struct *task, char *err_buf)
{
static unsigned long entries[MAX_STACK_ENTRIES];
- struct stack_trace trace;
struct klp_object *obj;
struct klp_func *func;
- int ret;
+ int ret, nr_entries;
- trace.skip = 0;
- trace.nr_entries = 0;
- trace.max_entries = MAX_STACK_ENTRIES;
- trace.entries = entries;
- ret = save_stack_trace_tsk_reliable(task, &trace);
- WARN_ON_ONCE(ret == -ENOSYS);
- if (ret) {
+ ret = stack_trace_save_tsk_reliable(task, entries, ARRAY_SIZE(entries));
+ if (ret < 0) {
snprintf(err_buf, STACK_ERR_BUF_SIZE,
"%s: %s:%d has an unreliable stack\n",
__func__, task->comm, task->pid);
return ret;
}
+ nr_entries = ret;
klp_for_each_object(klp_transition_patch, obj) {
if (!obj->patched)
continue;
klp_for_each_func(obj, func) {
- ret = klp_check_stack_func(func, &trace);
+ ret = klp_check_stack_func(func, entries, nr_entries);
if (ret) {
snprintf(err_buf, STACK_ERR_BUF_SIZE,
"%s: %s:%d is sleeping on function %s\n",
@@ -297,11 +280,11 @@
*/
static bool klp_try_switch_task(struct task_struct *task)
{
+ static char err_buf[STACK_ERR_BUF_SIZE];
struct rq *rq;
struct rq_flags flags;
int ret;
bool success = false;
- char err_buf[STACK_ERR_BUF_SIZE];
err_buf[0] = '\0';
@@ -310,6 +293,13 @@
return true;
/*
+ * For arches which don't have reliable stack traces, we have to rely
+ * on other methods (e.g., switching tasks at kernel exit).
+ */
+ if (!klp_have_reliable_stack())
+ return false;
+
+ /*
* Now try to check the stack for any to-be-patched or to-be-unpatched
* functions. If all goes well, switch the task to the target patch
* state.
@@ -344,7 +334,47 @@
pr_debug("%s", err_buf);
return success;
+}
+/*
+ * Sends a fake signal to all non-kthread tasks with TIF_PATCH_PENDING set.
+ * Kthreads with TIF_PATCH_PENDING set are woken up.
+ */
+static void klp_send_signals(void)
+{
+ struct task_struct *g, *task;
+
+ if (klp_signals_cnt == SIGNALS_TIMEOUT)
+ 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);
}
/*
@@ -359,6 +389,7 @@
{
unsigned int cpu;
struct task_struct *g, *task;
+ struct klp_patch *patch;
bool complete = true;
WARN_ON_ONCE(klp_target_state == KLP_UNDEFINED);
@@ -396,6 +427,10 @@
put_online_cpus();
if (!complete) {
+ if (klp_signals_cnt && !(klp_signals_cnt % SIGNALS_TIMEOUT))
+ klp_send_signals();
+ klp_signals_cnt++;
+
/*
* Some tasks weren't able to be switched over. Try again
* later and/or wait for other methods like kernel exit
@@ -407,7 +442,18 @@
}
/* we're done, now cleanup the data structures */
+ patch = klp_transition_patch;
klp_complete_transition();
+
+ /*
+ * It would make more sense to free the patch in
+ * klp_complete_transition() but it is called also
+ * from klp_cancel_transition().
+ */
+ if (!patch->enabled) {
+ klp_free_patch_start(patch);
+ schedule_work(&patch->free_work);
+ }
}
/*
@@ -446,6 +492,8 @@
if (task->patch_state != klp_target_state)
set_tsk_thread_flag(task, TIF_PATCH_PENDING);
}
+
+ klp_signals_cnt = 0;
}
/*
@@ -569,47 +617,6 @@
}
/*
- * 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.
*
@@ -620,6 +627,7 @@
*/
void klp_force_transition(void)
{
+ struct klp_patch *patch;
struct task_struct *g, *task;
unsigned int cpu;
@@ -633,5 +641,6 @@
for_each_possible_cpu(cpu)
klp_update_patch_state(idle_task(cpu));
- klp_forced = true;
+ klp_for_each_patch(patch)
+ patch->forced = true;
}
diff --git a/kernel/livepatch/transition.h b/kernel/livepatch/transition.h
index f9d0bc0..322db16 100644
--- a/kernel/livepatch/transition.h
+++ b/kernel/livepatch/transition.h
@@ -11,7 +11,6 @@
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 */