| /* |
| * 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> |
| |
| /** |
| * 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 |
| * 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). |
| * |
| * @node: node for the global klp_ops list |
| * @func_stack: list head for the stack of klp_func's (active func is on top) |
| * @fops: registered ftrace ops struct |
| */ |
| struct klp_ops { |
| struct list_head node; |
| struct list_head func_stack; |
| struct ftrace_ops fops; |
| }; |
| |
| /* |
| * The klp_mutex protects the global lists and state transitions of any |
| * structure reachable from them. References to any structure must be obtained |
| * under mutex protection (except in klp_ftrace_handler(), which uses RCU to |
| * ensure it gets consistent data). |
| */ |
| static DEFINE_MUTEX(klp_mutex); |
| |
| static LIST_HEAD(klp_patches); |
| static LIST_HEAD(klp_ops); |
| |
| static struct kobject *klp_root_kobj; |
| |
| static struct klp_ops *klp_find_ops(unsigned long old_addr) |
| { |
| struct klp_ops *ops; |
| struct klp_func *func; |
| |
| 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) |
| return ops; |
| } |
| |
| return NULL; |
| } |
| |
| 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?\n", |
| 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 *fops, |
| struct pt_regs *regs) |
| { |
| struct klp_ops *ops; |
| struct klp_func *func; |
| |
| ops = container_of(fops, struct klp_ops, fops); |
| |
| rcu_read_lock(); |
| func = list_first_or_null_rcu(&ops->func_stack, struct klp_func, |
| stack_node); |
| rcu_read_unlock(); |
| |
| if (WARN_ON_ONCE(!func)) |
| return; |
| |
| klp_arch_set_pc(regs, (unsigned long)func->new_func); |
| } |
| |
| static void klp_disable_func(struct klp_func *func) |
| { |
| struct klp_ops *ops; |
| |
| WARN_ON(func->state != KLP_ENABLED); |
| WARN_ON(!func->old_addr); |
| |
| ops = klp_find_ops(func->old_addr); |
| if (WARN_ON(!ops)) |
| return; |
| |
| if (list_is_singular(&ops->func_stack)) { |
| WARN_ON(unregister_ftrace_function(&ops->fops)); |
| WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0)); |
| |
| list_del_rcu(&func->stack_node); |
| list_del(&ops->node); |
| kfree(ops); |
| } else { |
| list_del_rcu(&func->stack_node); |
| } |
| |
| func->state = KLP_DISABLED; |
| } |
| |
| static int klp_enable_func(struct klp_func *func) |
| { |
| struct klp_ops *ops; |
| int ret; |
| |
| if (WARN_ON(!func->old_addr)) |
| return -EINVAL; |
| |
| if (WARN_ON(func->state != KLP_DISABLED)) |
| return -EINVAL; |
| |
| ops = klp_find_ops(func->old_addr); |
| if (!ops) { |
| ops = kzalloc(sizeof(*ops), GFP_KERNEL); |
| if (!ops) |
| return -ENOMEM; |
| |
| ops->fops.func = klp_ftrace_handler; |
| ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS | |
| FTRACE_OPS_FL_DYNAMIC | |
| FTRACE_OPS_FL_IPMODIFY; |
| |
| list_add(&ops->node, &klp_ops); |
| |
| INIT_LIST_HEAD(&ops->func_stack); |
| list_add_rcu(&func->stack_node, &ops->func_stack); |
| |
| ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 0, 0); |
| if (ret) { |
| pr_err("failed to set ftrace filter for function '%s' (%d)\n", |
| func->old_name, ret); |
| goto err; |
| } |
| |
| ret = register_ftrace_function(&ops->fops); |
| if (ret) { |
| pr_err("failed to register ftrace handler for function '%s' (%d)\n", |
| func->old_name, ret); |
| ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0); |
| goto err; |
| } |
| |
| |
| } else { |
| list_add_rcu(&func->stack_node, &ops->func_stack); |
| } |
| |
| func->state = KLP_ENABLED; |
| |
| return 0; |
| |
| err: |
| list_del_rcu(&func->stack_node); |
| list_del(&ops->node); |
| kfree(ops); |
| return ret; |
| } |
| |
| static void klp_disable_object(struct klp_object *obj) |
| { |
| struct klp_func *func; |
| |
| for (func = obj->funcs; func->old_name; func++) |
| if (func->state == KLP_ENABLED) |
| klp_disable_func(func); |
| |
| obj->state = KLP_DISABLED; |
| } |
| |
| 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) { |
| klp_disable_object(obj); |
| return ret; |
| } |
| } |
| obj->state = KLP_ENABLED; |
| |
| return 0; |
| } |
| |
| static int __klp_disable_patch(struct klp_patch *patch) |
| { |
| struct klp_object *obj; |
| |
| /* enforce stacking: only the last enabled patch can be disabled */ |
| if (!list_is_last(&patch->list, &klp_patches) && |
| list_next_entry(patch, list)->state == KLP_ENABLED) |
| return -EBUSY; |
| |
| pr_notice("disabling patch '%s'\n", patch->mod->name); |
| |
| for (obj = patch->objs; obj->funcs; obj++) { |
| if (obj->state == KLP_ENABLED) |
| klp_disable_object(obj); |
| } |
| |
| 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; |
| |
| /* enforce stacking: only the first disabled patch can be enabled */ |
| if (patch->list.prev != &klp_patches && |
| list_prev_entry(patch, list)->state == KLP_DISABLED) |
| return -EBUSY; |
| |
| 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++) { |
| 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) |
| { |
| } |
| |
| 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) |
| { |
| INIT_LIST_HEAD(&func->stack_node); |
| func->state = KLP_DISABLED; |
| |
| return kobject_init_and_add(&func->kobj, &klp_ktype_func, |
| obj->kobj, func->old_name); |
| } |
| |
| /* 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_tail(&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; |
| |
| if (patch->state == KLP_DISABLED) |
| goto disabled; |
| |
| pr_notice("reverting patch '%s' on unloading module '%s'\n", |
| pmod->name, mod->name); |
| |
| klp_disable_object(obj); |
| |
| 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 = klp_check_compiler_support(); |
| if (ret) { |
| pr_info("Your compiler is too old; turning off.\n"); |
| return -EINVAL; |
| } |
| |
| 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); |