|
|
@@ -0,0 +1,930 @@
|
|
|
+/*
|
|
|
+ * 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
|
|
|
+
|
|
|
+#include <linux/module.h>
|
|
|
+#include <linux/kernel.h>
|
|
|
+#include <linux/mutex.h>
|
|
|
+#include <linux/slab.h>
|
|
|
+#include <linux/ftrace.h>
|
|
|
+#include <linux/list.h>
|
|
|
+#include <linux/kallsyms.h>
|
|
|
+#include <linux/livepatch.h>
|
|
|
+
|
|
|
+/*
|
|
|
+ * The klp_mutex protects the klp_patches list and state transitions of any
|
|
|
+ * structure reachable from the patches list. References to any structure must
|
|
|
+ * be obtained under mutex protection.
|
|
|
+ */
|
|
|
+
|
|
|
+static DEFINE_MUTEX(klp_mutex);
|
|
|
+static LIST_HEAD(klp_patches);
|
|
|
+
|
|
|
+static struct kobject *klp_root_kobj;
|
|
|
+
|
|
|
+static bool klp_is_module(struct klp_object *obj)
|
|
|
+{
|
|
|
+ return obj->name;
|
|
|
+}
|
|
|
+
|
|
|
+static bool klp_is_object_loaded(struct klp_object *obj)
|
|
|
+{
|
|
|
+ return !obj->name || obj->mod;
|
|
|
+}
|
|
|
+
|
|
|
+/* sets obj->mod if object is not vmlinux and module is found */
|
|
|
+static void klp_find_object_module(struct klp_object *obj)
|
|
|
+{
|
|
|
+ if (!klp_is_module(obj))
|
|
|
+ return;
|
|
|
+
|
|
|
+ mutex_lock(&module_mutex);
|
|
|
+ /*
|
|
|
+ * We don't need to take a reference on the module here because we have
|
|
|
+ * the klp_mutex, which is also taken by the module notifier. This
|
|
|
+ * prevents any module from unloading until we release the klp_mutex.
|
|
|
+ */
|
|
|
+ obj->mod = find_module(obj->name);
|
|
|
+ mutex_unlock(&module_mutex);
|
|
|
+}
|
|
|
+
|
|
|
+/* klp_mutex must be held by caller */
|
|
|
+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;
|
|
|
+}
|
|
|
+
|
|
|
+struct klp_find_arg {
|
|
|
+ const char *objname;
|
|
|
+ const char *name;
|
|
|
+ unsigned long addr;
|
|
|
+ /*
|
|
|
+ * If count == 0, the symbol was not found. If count == 1, a unique
|
|
|
+ * match was found and addr is set. If count > 1, there is
|
|
|
+ * unresolvable ambiguity among "count" number of symbols with the same
|
|
|
+ * name in the same object.
|
|
|
+ */
|
|
|
+ unsigned long count;
|
|
|
+};
|
|
|
+
|
|
|
+static int klp_find_callback(void *data, const char *name,
|
|
|
+ struct module *mod, unsigned long addr)
|
|
|
+{
|
|
|
+ struct klp_find_arg *args = data;
|
|
|
+
|
|
|
+ if ((mod && !args->objname) || (!mod && args->objname))
|
|
|
+ return 0;
|
|
|
+
|
|
|
+ if (strcmp(args->name, name))
|
|
|
+ return 0;
|
|
|
+
|
|
|
+ if (args->objname && strcmp(args->objname, mod->name))
|
|
|
+ return 0;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * args->addr might be overwritten if another match is found
|
|
|
+ * but klp_find_object_symbol() handles this and only returns the
|
|
|
+ * addr if count == 1.
|
|
|
+ */
|
|
|
+ args->addr = addr;
|
|
|
+ args->count++;
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static int klp_find_object_symbol(const char *objname, const char *name,
|
|
|
+ unsigned long *addr)
|
|
|
+{
|
|
|
+ struct klp_find_arg args = {
|
|
|
+ .objname = objname,
|
|
|
+ .name = name,
|
|
|
+ .addr = 0,
|
|
|
+ .count = 0
|
|
|
+ };
|
|
|
+
|
|
|
+ kallsyms_on_each_symbol(klp_find_callback, &args);
|
|
|
+
|
|
|
+ if (args.count == 0)
|
|
|
+ pr_err("symbol '%s' not found in symbol table\n", name);
|
|
|
+ else if (args.count > 1)
|
|
|
+ pr_err("unresolvable ambiguity (%lu matches) on symbol '%s' in object '%s'\n",
|
|
|
+ args.count, name, objname);
|
|
|
+ else {
|
|
|
+ *addr = args.addr;
|
|
|
+ return 0;
|
|
|
+ }
|
|
|
+
|
|
|
+ *addr = 0;
|
|
|
+ return -EINVAL;
|
|
|
+}
|
|
|
+
|
|
|
+struct klp_verify_args {
|
|
|
+ const char *name;
|
|
|
+ const unsigned long addr;
|
|
|
+};
|
|
|
+
|
|
|
+static int klp_verify_callback(void *data, const char *name,
|
|
|
+ struct module *mod, unsigned long addr)
|
|
|
+{
|
|
|
+ struct klp_verify_args *args = data;
|
|
|
+
|
|
|
+ if (!mod &&
|
|
|
+ !strcmp(args->name, name) &&
|
|
|
+ args->addr == addr)
|
|
|
+ return 1;
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr)
|
|
|
+{
|
|
|
+ struct klp_verify_args args = {
|
|
|
+ .name = name,
|
|
|
+ .addr = addr,
|
|
|
+ };
|
|
|
+
|
|
|
+ if (kallsyms_on_each_symbol(klp_verify_callback, &args))
|
|
|
+ return 0;
|
|
|
+
|
|
|
+ pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?",
|
|
|
+ name, addr);
|
|
|
+ return -EINVAL;
|
|
|
+}
|
|
|
+
|
|
|
+static int klp_find_verify_func_addr(struct klp_object *obj,
|
|
|
+ struct klp_func *func)
|
|
|
+{
|
|
|
+ int ret;
|
|
|
+
|
|
|
+#if defined(CONFIG_RANDOMIZE_BASE)
|
|
|
+ /* KASLR is enabled, disregard old_addr from user */
|
|
|
+ func->old_addr = 0;
|
|
|
+#endif
|
|
|
+
|
|
|
+ if (!func->old_addr || klp_is_module(obj))
|
|
|
+ ret = klp_find_object_symbol(obj->name, func->old_name,
|
|
|
+ &func->old_addr);
|
|
|
+ else
|
|
|
+ ret = klp_verify_vmlinux_symbol(func->old_name,
|
|
|
+ func->old_addr);
|
|
|
+
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * external symbols are located outside the parent object (where the parent
|
|
|
+ * object is either vmlinux or the kmod being patched).
|
|
|
+ */
|
|
|
+static int klp_find_external_symbol(struct module *pmod, const char *name,
|
|
|
+ unsigned long *addr)
|
|
|
+{
|
|
|
+ const struct kernel_symbol *sym;
|
|
|
+
|
|
|
+ /* first, check if it's an exported symbol */
|
|
|
+ preempt_disable();
|
|
|
+ sym = find_symbol(name, NULL, NULL, true, true);
|
|
|
+ preempt_enable();
|
|
|
+ if (sym) {
|
|
|
+ *addr = sym->value;
|
|
|
+ return 0;
|
|
|
+ }
|
|
|
+
|
|
|
+ /* otherwise check if it's in another .o within the patch module */
|
|
|
+ return klp_find_object_symbol(pmod->name, name, addr);
|
|
|
+}
|
|
|
+
|
|
|
+static int klp_write_object_relocations(struct module *pmod,
|
|
|
+ struct klp_object *obj)
|
|
|
+{
|
|
|
+ int ret;
|
|
|
+ struct klp_reloc *reloc;
|
|
|
+
|
|
|
+ if (WARN_ON(!klp_is_object_loaded(obj)))
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ if (WARN_ON(!obj->relocs))
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ for (reloc = obj->relocs; reloc->name; reloc++) {
|
|
|
+ if (!klp_is_module(obj)) {
|
|
|
+ ret = klp_verify_vmlinux_symbol(reloc->name,
|
|
|
+ reloc->val);
|
|
|
+ if (ret)
|
|
|
+ return ret;
|
|
|
+ } else {
|
|
|
+ /* module, reloc->val needs to be discovered */
|
|
|
+ if (reloc->external)
|
|
|
+ ret = klp_find_external_symbol(pmod,
|
|
|
+ reloc->name,
|
|
|
+ &reloc->val);
|
|
|
+ else
|
|
|
+ ret = klp_find_object_symbol(obj->mod->name,
|
|
|
+ reloc->name,
|
|
|
+ &reloc->val);
|
|
|
+ if (ret)
|
|
|
+ return ret;
|
|
|
+ }
|
|
|
+ ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc,
|
|
|
+ reloc->val + reloc->addend);
|
|
|
+ if (ret) {
|
|
|
+ pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n",
|
|
|
+ reloc->name, reloc->val, ret);
|
|
|
+ return ret;
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static void notrace klp_ftrace_handler(unsigned long ip,
|
|
|
+ unsigned long parent_ip,
|
|
|
+ struct ftrace_ops *ops,
|
|
|
+ struct pt_regs *regs)
|
|
|
+{
|
|
|
+ struct klp_func *func = ops->private;
|
|
|
+
|
|
|
+ regs->ip = (unsigned long)func->new_func;
|
|
|
+}
|
|
|
+
|
|
|
+static int klp_disable_func(struct klp_func *func)
|
|
|
+{
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ if (WARN_ON(func->state != KLP_ENABLED))
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ if (WARN_ON(!func->old_addr))
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ ret = unregister_ftrace_function(func->fops);
|
|
|
+ if (ret) {
|
|
|
+ pr_err("failed to unregister ftrace handler for function '%s' (%d)\n",
|
|
|
+ func->old_name, ret);
|
|
|
+ return ret;
|
|
|
+ }
|
|
|
+
|
|
|
+ ret = ftrace_set_filter_ip(func->fops, func->old_addr, 1, 0);
|
|
|
+ if (ret)
|
|
|
+ pr_warn("function unregister succeeded but failed to clear the filter\n");
|
|
|
+
|
|
|
+ func->state = KLP_DISABLED;
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static int klp_enable_func(struct klp_func *func)
|
|
|
+{
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ if (WARN_ON(!func->old_addr))
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ if (WARN_ON(func->state != KLP_DISABLED))
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ ret = ftrace_set_filter_ip(func->fops, func->old_addr, 0, 0);
|
|
|
+ if (ret) {
|
|
|
+ pr_err("failed to set ftrace filter for function '%s' (%d)\n",
|
|
|
+ func->old_name, ret);
|
|
|
+ return ret;
|
|
|
+ }
|
|
|
+
|
|
|
+ ret = register_ftrace_function(func->fops);
|
|
|
+ if (ret) {
|
|
|
+ pr_err("failed to register ftrace handler for function '%s' (%d)\n",
|
|
|
+ func->old_name, ret);
|
|
|
+ ftrace_set_filter_ip(func->fops, func->old_addr, 1, 0);
|
|
|
+ } else {
|
|
|
+ func->state = KLP_ENABLED;
|
|
|
+ }
|
|
|
+
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+
|
|
|
+static int klp_disable_object(struct klp_object *obj)
|
|
|
+{
|
|
|
+ struct klp_func *func;
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ for (func = obj->funcs; func->old_name; func++) {
|
|
|
+ if (func->state != KLP_ENABLED)
|
|
|
+ continue;
|
|
|
+
|
|
|
+ ret = klp_disable_func(func);
|
|
|
+ if (ret)
|
|
|
+ return ret;
|
|
|
+ }
|
|
|
+
|
|
|
+ obj->state = KLP_DISABLED;
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static int klp_enable_object(struct klp_object *obj)
|
|
|
+{
|
|
|
+ struct klp_func *func;
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ if (WARN_ON(obj->state != KLP_DISABLED))
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ if (WARN_ON(!klp_is_object_loaded(obj)))
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ for (func = obj->funcs; func->old_name; func++) {
|
|
|
+ ret = klp_enable_func(func);
|
|
|
+ if (ret)
|
|
|
+ goto unregister;
|
|
|
+ }
|
|
|
+ obj->state = KLP_ENABLED;
|
|
|
+
|
|
|
+ return 0;
|
|
|
+
|
|
|
+unregister:
|
|
|
+ WARN_ON(klp_disable_object(obj));
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+
|
|
|
+static int __klp_disable_patch(struct klp_patch *patch)
|
|
|
+{
|
|
|
+ struct klp_object *obj;
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ pr_notice("disabling patch '%s'\n", patch->mod->name);
|
|
|
+
|
|
|
+ for (obj = patch->objs; obj->funcs; obj++) {
|
|
|
+ if (obj->state != KLP_ENABLED)
|
|
|
+ continue;
|
|
|
+
|
|
|
+ ret = klp_disable_object(obj);
|
|
|
+ if (ret)
|
|
|
+ return ret;
|
|
|
+ }
|
|
|
+
|
|
|
+ patch->state = KLP_DISABLED;
|
|
|
+
|
|
|
+ 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->state == KLP_DISABLED) {
|
|
|
+ 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;
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ if (WARN_ON(patch->state != KLP_DISABLED))
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n");
|
|
|
+ add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK);
|
|
|
+
|
|
|
+ pr_notice("enabling patch '%s'\n", patch->mod->name);
|
|
|
+
|
|
|
+ for (obj = patch->objs; obj->funcs; obj++) {
|
|
|
+ klp_find_object_module(obj);
|
|
|
+
|
|
|
+ if (!klp_is_object_loaded(obj))
|
|
|
+ continue;
|
|
|
+
|
|
|
+ ret = klp_enable_object(obj);
|
|
|
+ if (ret)
|
|
|
+ goto unregister;
|
|
|
+ }
|
|
|
+
|
|
|
+ patch->state = KLP_ENABLED;
|
|
|
+
|
|
|
+ return 0;
|
|
|
+
|
|
|
+unregister:
|
|
|
+ WARN_ON(__klp_disable_patch(patch));
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * klp_enable_patch() - enables a registered patch
|
|
|
+ * @patch: The registered, disabled patch to be enabled
|
|
|
+ *
|
|
|
+ * Performs the needed symbol lookups and code relocations,
|
|
|
+ * then registers the patched functions with ftrace.
|
|
|
+ *
|
|
|
+ * Return: 0 on success, otherwise error
|
|
|
+ */
|
|
|
+int klp_enable_patch(struct klp_patch *patch)
|
|
|
+{
|
|
|
+ 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>/<object>
|
|
|
+ * /sys/kernel/livepatch/<patch>/<object>/<func>
|
|
|
+ */
|
|
|
+
|
|
|
+static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
|
|
|
+ const char *buf, size_t count)
|
|
|
+{
|
|
|
+ struct klp_patch *patch;
|
|
|
+ int ret;
|
|
|
+ unsigned long val;
|
|
|
+
|
|
|
+ ret = kstrtoul(buf, 10, &val);
|
|
|
+ if (ret)
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ if (val != KLP_DISABLED && val != KLP_ENABLED)
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ patch = container_of(kobj, struct klp_patch, kobj);
|
|
|
+
|
|
|
+ mutex_lock(&klp_mutex);
|
|
|
+
|
|
|
+ if (val == patch->state) {
|
|
|
+ /* already in requested state */
|
|
|
+ ret = -EINVAL;
|
|
|
+ goto err;
|
|
|
+ }
|
|
|
+
|
|
|
+ if (val == KLP_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->state);
|
|
|
+}
|
|
|
+
|
|
|
+static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled);
|
|
|
+static struct attribute *klp_patch_attrs[] = {
|
|
|
+ &enabled_kobj_attr.attr,
|
|
|
+ NULL
|
|
|
+};
|
|
|
+
|
|
|
+static void klp_kobj_release_patch(struct kobject *kobj)
|
|
|
+{
|
|
|
+ /*
|
|
|
+ * Once we have a consistency model we'll need to module_put() the
|
|
|
+ * patch module here. See klp_register_patch() for more details.
|
|
|
+ */
|
|
|
+}
|
|
|
+
|
|
|
+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_func(struct kobject *kobj)
|
|
|
+{
|
|
|
+ struct klp_func *func;
|
|
|
+
|
|
|
+ func = container_of(kobj, struct klp_func, kobj);
|
|
|
+ kfree(func->fops);
|
|
|
+}
|
|
|
+
|
|
|
+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;
|
|
|
+
|
|
|
+ for (func = obj->funcs; func->old_name; 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);
|
|
|
+ kobject_put(&patch->kobj);
|
|
|
+}
|
|
|
+
|
|
|
+static int klp_init_func(struct klp_object *obj, struct klp_func *func)
|
|
|
+{
|
|
|
+ struct ftrace_ops *ops;
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ ops = kzalloc(sizeof(*ops), GFP_KERNEL);
|
|
|
+ if (!ops)
|
|
|
+ return -ENOMEM;
|
|
|
+
|
|
|
+ ops->private = func;
|
|
|
+ ops->func = klp_ftrace_handler;
|
|
|
+ ops->flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_DYNAMIC;
|
|
|
+ func->fops = ops;
|
|
|
+ func->state = KLP_DISABLED;
|
|
|
+
|
|
|
+ ret = kobject_init_and_add(&func->kobj, &klp_ktype_func,
|
|
|
+ obj->kobj, func->old_name);
|
|
|
+ if (ret) {
|
|
|
+ kfree(func->fops);
|
|
|
+ return ret;
|
|
|
+ }
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+/* 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;
|
|
|
+
|
|
|
+ if (obj->relocs) {
|
|
|
+ ret = klp_write_object_relocations(patch->mod, obj);
|
|
|
+ if (ret)
|
|
|
+ return ret;
|
|
|
+ }
|
|
|
+
|
|
|
+ for (func = obj->funcs; func->old_name; func++) {
|
|
|
+ ret = klp_find_verify_func_addr(obj, func);
|
|
|
+ if (ret)
|
|
|
+ return ret;
|
|
|
+ }
|
|
|
+
|
|
|
+ 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;
|
|
|
+
|
|
|
+ obj->state = KLP_DISABLED;
|
|
|
+
|
|
|
+ klp_find_object_module(obj);
|
|
|
+
|
|
|
+ name = klp_is_module(obj) ? obj->name : "vmlinux";
|
|
|
+ obj->kobj = kobject_create_and_add(name, &patch->kobj);
|
|
|
+ if (!obj->kobj)
|
|
|
+ return -ENOMEM;
|
|
|
+
|
|
|
+ for (func = obj->funcs; func->old_name; 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->state = KLP_DISABLED;
|
|
|
+
|
|
|
+ ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch,
|
|
|
+ klp_root_kobj, patch->mod->name);
|
|
|
+ if (ret)
|
|
|
+ goto unlock;
|
|
|
+
|
|
|
+ for (obj = patch->objs; obj->funcs; obj++) {
|
|
|
+ ret = klp_init_object(patch, obj);
|
|
|
+ if (ret)
|
|
|
+ goto free;
|
|
|
+ }
|
|
|
+
|
|
|
+ list_add(&patch->list, &klp_patches);
|
|
|
+
|
|
|
+ mutex_unlock(&klp_mutex);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+
|
|
|
+free:
|
|
|
+ klp_free_objects_limited(patch, obj);
|
|
|
+ kobject_put(&patch->kobj);
|
|
|
+unlock:
|
|
|
+ mutex_unlock(&klp_mutex);
|
|
|
+ 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 = 0;
|
|
|
+
|
|
|
+ mutex_lock(&klp_mutex);
|
|
|
+
|
|
|
+ if (!klp_is_patch_registered(patch)) {
|
|
|
+ ret = -EINVAL;
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+
|
|
|
+ if (patch->state == KLP_ENABLED) {
|
|
|
+ ret = -EBUSY;
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+
|
|
|
+ klp_free_patch(patch);
|
|
|
+
|
|
|
+out:
|
|
|
+ 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.
|
|
|
+ *
|
|
|
+ * Return: 0 on success, otherwise error
|
|
|
+ */
|
|
|
+int klp_register_patch(struct klp_patch *patch)
|
|
|
+{
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ if (!klp_initialized())
|
|
|
+ return -ENODEV;
|
|
|
+
|
|
|
+ if (!patch || !patch->mod)
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * A reference is taken on the patch module to prevent it from being
|
|
|
+ * unloaded. Right now, we don't allow patch modules to unload since
|
|
|
+ * there is currently no 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;
|
|
|
+
|
|
|
+ ret = klp_init_patch(patch);
|
|
|
+ if (ret)
|
|
|
+ module_put(patch->mod);
|
|
|
+
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(klp_register_patch);
|
|
|
+
|
|
|
+static void klp_module_notify_coming(struct klp_patch *patch,
|
|
|
+ struct klp_object *obj)
|
|
|
+{
|
|
|
+ struct module *pmod = patch->mod;
|
|
|
+ struct module *mod = obj->mod;
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ ret = klp_init_object_loaded(patch, obj);
|
|
|
+ if (ret)
|
|
|
+ goto err;
|
|
|
+
|
|
|
+ if (patch->state == KLP_DISABLED)
|
|
|
+ return;
|
|
|
+
|
|
|
+ pr_notice("applying patch '%s' to loading module '%s'\n",
|
|
|
+ pmod->name, mod->name);
|
|
|
+
|
|
|
+ ret = klp_enable_object(obj);
|
|
|
+ if (!ret)
|
|
|
+ return;
|
|
|
+
|
|
|
+err:
|
|
|
+ pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
|
|
|
+ pmod->name, mod->name, ret);
|
|
|
+}
|
|
|
+
|
|
|
+static void klp_module_notify_going(struct klp_patch *patch,
|
|
|
+ struct klp_object *obj)
|
|
|
+{
|
|
|
+ struct module *pmod = patch->mod;
|
|
|
+ struct module *mod = obj->mod;
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ if (patch->state == KLP_DISABLED)
|
|
|
+ goto disabled;
|
|
|
+
|
|
|
+ pr_notice("reverting patch '%s' on unloading module '%s'\n",
|
|
|
+ pmod->name, mod->name);
|
|
|
+
|
|
|
+ ret = klp_disable_object(obj);
|
|
|
+ if (ret)
|
|
|
+ pr_warn("failed to revert patch '%s' on module '%s' (%d)\n",
|
|
|
+ pmod->name, mod->name, ret);
|
|
|
+
|
|
|
+disabled:
|
|
|
+ klp_free_object_loaded(obj);
|
|
|
+}
|
|
|
+
|
|
|
+static int klp_module_notify(struct notifier_block *nb, unsigned long action,
|
|
|
+ void *data)
|
|
|
+{
|
|
|
+ struct module *mod = data;
|
|
|
+ struct klp_patch *patch;
|
|
|
+ struct klp_object *obj;
|
|
|
+
|
|
|
+ if (action != MODULE_STATE_COMING && action != MODULE_STATE_GOING)
|
|
|
+ return 0;
|
|
|
+
|
|
|
+ mutex_lock(&klp_mutex);
|
|
|
+
|
|
|
+ list_for_each_entry(patch, &klp_patches, list) {
|
|
|
+ for (obj = patch->objs; obj->funcs; obj++) {
|
|
|
+ if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
|
|
|
+ continue;
|
|
|
+
|
|
|
+ if (action == MODULE_STATE_COMING) {
|
|
|
+ obj->mod = mod;
|
|
|
+ klp_module_notify_coming(patch, obj);
|
|
|
+ } else /* MODULE_STATE_GOING */
|
|
|
+ klp_module_notify_going(patch, obj);
|
|
|
+
|
|
|
+ break;
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ mutex_unlock(&klp_mutex);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static struct notifier_block klp_module_nb = {
|
|
|
+ .notifier_call = klp_module_notify,
|
|
|
+ .priority = INT_MIN+1, /* called late but before ftrace notifier */
|
|
|
+};
|
|
|
+
|
|
|
+static int klp_init(void)
|
|
|
+{
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ ret = register_module_notifier(&klp_module_nb);
|
|
|
+ if (ret)
|
|
|
+ return ret;
|
|
|
+
|
|
|
+ klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj);
|
|
|
+ if (!klp_root_kobj) {
|
|
|
+ ret = -ENOMEM;
|
|
|
+ goto unregister;
|
|
|
+ }
|
|
|
+
|
|
|
+ return 0;
|
|
|
+
|
|
|
+unregister:
|
|
|
+ unregister_module_notifier(&klp_module_nb);
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+
|
|
|
+module_init(klp_init);
|
Seth Jennings