diff options
Diffstat (limited to 'kernel/livepatch/core.c')
| -rw-r--r-- | kernel/livepatch/core.c | 1073 |
1 files changed, 1073 insertions, 0 deletions
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c new file mode 100644 index 000000000..a1250ad59 --- /dev/null +++ b/kernel/livepatch/core.c @@ -0,0 +1,1073 @@ +/* + * 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/list.h> +#include <linux/kallsyms.h> +#include <linux/livepatch.h> +#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" +#include "transition.h" + +/* + * klp_mutex is a coarse lock which serializes access to klp data. All + * accesses to klp-related variables and structures must have mutex protection, + * except within the following functions which carefully avoid the need for it: + * + * - klp_ftrace_handler() + * - klp_update_patch_state() + */ +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; +} + +/* sets obj->mod if object is not vmlinux and module is found */ +static void klp_find_object_module(struct klp_object *obj) +{ + struct module *mod; + + if (!klp_is_module(obj)) + return; + + mutex_lock(&module_mutex); + /* + * We do not want to block removal of patched modules and therefore + * we do not take a reference here. The patches are removed by + * klp_module_going() instead. + */ + mod = find_module(obj->name); + /* + * Do not mess work of klp_module_coming() and klp_module_going(). + * Note that the patch might still be needed before klp_module_going() + * is called. Module functions can be called even in the GOING state + * until mod->exit() finishes. This is especially important for + * patches that modify semantic of the functions. + */ + if (mod && mod->klp_alive) + obj->mod = mod; + + 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; +} + +struct klp_find_arg { + const char *objname; + const char *name; + unsigned long addr; + unsigned long count; + unsigned long pos; +}; + +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 = addr; + args->count++; + + /* + * Finish the search when the symbol is found for the desired position + * or the position is not defined for a non-unique symbol. + */ + if ((args->pos && (args->count == args->pos)) || + (!args->pos && (args->count > 1))) + return 1; + + return 0; +} + +static int klp_find_object_symbol(const char *objname, const char *name, + unsigned long sympos, unsigned long *addr) +{ + struct klp_find_arg args = { + .objname = objname, + .name = name, + .addr = 0, + .count = 0, + .pos = sympos, + }; + + mutex_lock(&module_mutex); + if (objname) + module_kallsyms_on_each_symbol(klp_find_callback, &args); + else + kallsyms_on_each_symbol(klp_find_callback, &args); + mutex_unlock(&module_mutex); + + /* + * Ensure an address was found. If sympos is 0, ensure symbol is unique; + * otherwise ensure the symbol position count matches sympos. + */ + if (args.addr == 0) + pr_err("symbol '%s' not found in symbol table\n", name); + else if (args.count > 1 && sympos == 0) { + pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n", + name, objname); + } else if (sympos != args.count && sympos > 0) { + pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n", + sympos, name, objname ? objname : "vmlinux"); + } else { + *addr = args.addr; + return 0; + } + + *addr = 0; + return -EINVAL; +} + +static int klp_resolve_symbols(Elf_Shdr *relasec, struct module *pmod) +{ + int i, cnt, vmlinux, ret; + char objname[MODULE_NAME_LEN]; + char symname[KSYM_NAME_LEN]; + char *strtab = pmod->core_kallsyms.strtab; + Elf_Rela *relas; + Elf_Sym *sym; + unsigned long sympos, addr; + + /* + * Since the field widths for objname and symname in the sscanf() + * call are hard-coded and correspond to MODULE_NAME_LEN and + * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN + * and KSYM_NAME_LEN have the values we expect them to have. + * + * Because the value of MODULE_NAME_LEN can differ among architectures, + * we use the smallest/strictest upper bound possible (56, based on + * the current definition of MODULE_NAME_LEN) to prevent overflows. + */ + BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128); + + relas = (Elf_Rela *) relasec->sh_addr; + /* For each rela in this klp relocation section */ + for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) { + sym = pmod->core_kallsyms.symtab + ELF_R_SYM(relas[i].r_info); + if (sym->st_shndx != SHN_LIVEPATCH) { + pr_err("symbol %s is not marked as a livepatch symbol\n", + strtab + sym->st_name); + return -EINVAL; + } + + /* Format: .klp.sym.objname.symname,sympos */ + cnt = sscanf(strtab + sym->st_name, + ".klp.sym.%55[^.].%127[^,],%lu", + objname, symname, &sympos); + if (cnt != 3) { + pr_err("symbol %s has an incorrectly formatted name\n", + strtab + sym->st_name); + return -EINVAL; + } + + /* klp_find_object_symbol() treats a NULL objname as vmlinux */ + vmlinux = !strcmp(objname, "vmlinux"); + ret = klp_find_object_symbol(vmlinux ? NULL : objname, + symname, sympos, &addr); + if (ret) + return ret; + + sym->st_value = addr; + } + + return 0; +} + +static int klp_write_object_relocations(struct module *pmod, + struct klp_object *obj) +{ + int i, cnt, ret = 0; + const char *objname, *secname; + char sec_objname[MODULE_NAME_LEN]; + Elf_Shdr *sec; + + if (WARN_ON(!klp_is_object_loaded(obj))) + return -EINVAL; + + objname = klp_is_module(obj) ? obj->name : "vmlinux"; + + /* For each klp relocation section */ + for (i = 1; i < pmod->klp_info->hdr.e_shnum; i++) { + sec = pmod->klp_info->sechdrs + i; + secname = pmod->klp_info->secstrings + sec->sh_name; + if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) + continue; + + /* + * Format: .klp.rela.sec_objname.section_name + * See comment in klp_resolve_symbols() for an explanation + * of the selected field width value. + */ + cnt = sscanf(secname, ".klp.rela.%55[^.]", sec_objname); + if (cnt != 1) { + pr_err("section %s has an incorrectly formatted name\n", + secname); + ret = -EINVAL; + break; + } + + if (strcmp(objname, sec_objname)) + continue; + + ret = klp_resolve_symbols(sec, pmod); + if (ret) + break; + + ret = apply_relocate_add(pmod->klp_info->sechdrs, + pmod->core_kallsyms.strtab, + pmod->klp_info->symndx, i, pmod); + if (ret) + break; + } + + return ret; +} + +static int __klp_disable_patch(struct klp_patch *patch) +{ + struct klp_object *obj; + + if (WARN_ON(!patch->enabled)) + return -EINVAL; + + 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) + if (obj->patched) + klp_pre_unpatch_callback(obj); + + /* + * Enforce the order of the func->transition writes in + * klp_init_transition() and the TIF_PATCH_PENDING writes in + * klp_start_transition(). In the rare case where klp_ftrace_handler() + * is called shortly after klp_update_patch_state() switches the task, + * this ensures the handler sees that func->transition is set. + */ + smp_wmb(); + + klp_start_transition(); + klp_try_complete_transition(); + patch->enabled = false; + + 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; + int ret; + + if (klp_transition_patch) + return -EBUSY; + + 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); + + /* + * Enforce the order of the func->transition writes in + * klp_init_transition() and the ops->func_stack writes in + * klp_patch_object(), so that klp_ftrace_handler() will see the + * func->transition updates before the handler is registered and the + * new funcs become visible to the handler. + */ + smp_wmb(); + + klp_for_each_object(patch, obj) { + if (!klp_is_object_loaded(obj)) + continue; + + ret = klp_pre_patch_callback(obj); + if (ret) { + pr_warn("pre-patch callback failed for object '%s'\n", + klp_is_module(obj) ? obj->name : "vmlinux"); + goto err; + } + + ret = klp_patch_object(obj); + if (ret) { + pr_warn("failed to patch object '%s'\n", + klp_is_module(obj) ? obj->name : "vmlinux"); + goto err; + } + } + + klp_start_transition(); + klp_try_complete_transition(); + patch->enabled = true; + + return 0; +err: + pr_warn("failed to enable patch '%s'\n", patch->mod->name); + + klp_cancel_transition(); + 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>/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; + + 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, + &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; + + if (!is_livepatch_module(patch->mod)) { + pr_err("module %s is not marked as a livepatch module\n", + patch->mod->name); + return -EINVAL; + } + + if (!klp_initialized()) + return -ENODEV; + + if (!klp_have_reliable_stack()) { + pr_err("This architecture doesn't have support for the livepatch consistency model.\n"); + return -ENOSYS; + } + + return klp_init_patch(patch); +} +EXPORT_SYMBOL_GPL(klp_register_patch); + +/* + * Remove parts of patches that touch a given kernel module. The list of + * patches processed might be limited. When limit is NULL, all patches + * will be handled. + */ +static void klp_cleanup_module_patches_limited(struct module *mod, + struct klp_patch *limit) +{ + struct klp_patch *patch; + struct klp_object *obj; + + list_for_each_entry(patch, &klp_patches, list) { + if (patch == limit) + break; + + klp_for_each_object(patch, obj) { + 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); + + 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_free_object_loaded(obj); + break; + } + } +} + +int klp_module_coming(struct module *mod) +{ + int ret; + struct klp_patch *patch; + struct klp_object *obj; + + if (WARN_ON(mod->state != MODULE_STATE_COMING)) + return -EINVAL; + + mutex_lock(&klp_mutex); + /* + * Each module has to know that klp_module_coming() + * has been called. We never know what module will + * get patched by a new patch. + */ + mod->klp_alive = true; + + list_for_each_entry(patch, &klp_patches, list) { + klp_for_each_object(patch, obj) { + if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) + continue; + + obj->mod = mod; + + ret = klp_init_object_loaded(patch, obj); + if (ret) { + pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", + patch->mod->name, obj->mod->name, ret); + 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); + + ret = klp_pre_patch_callback(obj); + if (ret) { + pr_warn("pre-patch callback failed for object '%s'\n", + obj->name); + goto err; + } + + ret = klp_patch_object(obj); + if (ret) { + pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", + patch->mod->name, obj->mod->name, ret); + + klp_post_unpatch_callback(obj); + goto err; + } + + if (patch != klp_transition_patch) + klp_post_patch_callback(obj); + + break; + } + } + + mutex_unlock(&klp_mutex); + + return 0; + +err: + /* + * If a patch is unsuccessfully applied, return + * error to the module loader. + */ + 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); + + return ret; +} + +void klp_module_going(struct module *mod) +{ + if (WARN_ON(mod->state != MODULE_STATE_GOING && + mod->state != MODULE_STATE_COMING)) + return; + + mutex_lock(&klp_mutex); + /* + * Each module has to know that klp_module_going() + * has been called. We never know what module will + * get patched by a new patch. + */ + mod->klp_alive = false; + + klp_cleanup_module_patches_limited(mod, NULL); + + mutex_unlock(&klp_mutex); +} + +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; + + return 0; +} + +module_init(klp_init); |