| /* |
| * 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> |
| #include <linux/elf.h> |
| #include <linux/moduleloader.h> |
| #include <asm/cacheflush.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) |
| { |
| 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); |
| } |
| |
| /* 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; |
| 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); |
| 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", |
| 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", |
| 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"; |
| |
| module_disable_ro(pmod); |
| /* 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", |
| 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; |
| } |
| |
| module_enable_ro(pmod); |
| return ret; |
| } |
| |
| 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); |
| if (WARN_ON_ONCE(!func)) |
| goto unlock; |
| |
| klp_arch_set_pc(regs, (unsigned long)func->new_func); |
| unlock: |
| rcu_read_unlock(); |
| } |
| |
| static void klp_disable_func(struct klp_func *func) |
| { |
| struct klp_ops *ops; |
| |
| if (WARN_ON(func->state != KLP_ENABLED)) |
| return; |
| if (WARN_ON(!func->old_addr)) |
| return; |
| |
| 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; |
| |
| klp_for_each_func(obj, 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; |
| |
| klp_for_each_func(obj, 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); |
| |
| klp_for_each_object(patch, 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); |
| |
| klp_for_each_object(patch, 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>/<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; |
| 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_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); |
| 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; |
| |
| /* 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); |
| } |
| |
| /* 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; |
| |
| ret = klp_write_object_relocations(patch->mod, obj); |
| if (ret) |
| return ret; |
| |
| 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; |
| } |
| |
| 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; |
| 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->state = KLP_DISABLED; |
| |
| ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch, |
| klp_root_kobj, "%s", patch->mod->name); |
| if (ret) |
| goto unlock; |
| |
| 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); |
| 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 (!is_livepatch_module(patch->mod)) { |
| pr_err("module %s is not marked as a livepatch module", |
| patch->mod->name); |
| return -EINVAL; |
| } |
| |
| 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); |
| |
| 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; |
| } |
| |
| if (patch->state == KLP_DISABLED) |
| break; |
| |
| pr_notice("applying patch '%s' to loading module '%s'\n", |
| patch->mod->name, obj->mod->name); |
| |
| ret = klp_enable_object(obj); |
| if (ret) { |
| pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", |
| patch->mod->name, obj->mod->name, ret); |
| goto err; |
| } |
| |
| 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; |
| klp_free_object_loaded(obj); |
| mutex_unlock(&klp_mutex); |
| |
| return ret; |
| } |
| |
| void klp_module_going(struct module *mod) |
| { |
| struct klp_patch *patch; |
| struct klp_object *obj; |
| |
| 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; |
| |
| 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; |
| |
| if (patch->state != KLP_DISABLED) { |
| pr_notice("reverting patch '%s' on unloading module '%s'\n", |
| patch->mod->name, obj->mod->name); |
| klp_disable_object(obj); |
| } |
| |
| klp_free_object_loaded(obj); |
| break; |
| } |
| } |
| |
| 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); |