![Minfei Huang](/assets/img/avatar_default.png)
In case of func->state or func->old_addr not having expected values, we'd rather bail out immediately from klp_disable_func(). This can't really happen with the current codebase, but fix this anyway in the sake of robustness. [jkosina@suse.com: reworded the changelog a bit] Signed-off-by: Minfei Huang <mnfhuang@gmail.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.com>
1032 lines
22 KiB
C
1032 lines
22 KiB
C
/*
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* core.c - Kernel Live Patching Core
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*
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* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
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* Copyright (C) 2014 SUSE
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/ftrace.h>
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#include <linux/list.h>
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#include <linux/kallsyms.h>
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#include <linux/livepatch.h>
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/**
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* struct klp_ops - structure for tracking registered ftrace ops structs
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*
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* A single ftrace_ops is shared between all enabled replacement functions
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* (klp_func structs) which have the same old_addr. This allows the switch
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* between function versions to happen instantaneously by updating the klp_ops
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* struct's func_stack list. The winner is the klp_func at the top of the
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* func_stack (front of the list).
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*
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* @node: node for the global klp_ops list
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* @func_stack: list head for the stack of klp_func's (active func is on top)
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* @fops: registered ftrace ops struct
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*/
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struct klp_ops {
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struct list_head node;
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struct list_head func_stack;
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struct ftrace_ops fops;
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};
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/*
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* The klp_mutex protects the global lists and state transitions of any
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* structure reachable from them. References to any structure must be obtained
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* under mutex protection (except in klp_ftrace_handler(), which uses RCU to
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* ensure it gets consistent data).
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*/
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static DEFINE_MUTEX(klp_mutex);
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static LIST_HEAD(klp_patches);
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static LIST_HEAD(klp_ops);
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static struct kobject *klp_root_kobj;
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static struct klp_ops *klp_find_ops(unsigned long old_addr)
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{
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struct klp_ops *ops;
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struct klp_func *func;
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list_for_each_entry(ops, &klp_ops, node) {
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func = list_first_entry(&ops->func_stack, struct klp_func,
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stack_node);
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if (func->old_addr == old_addr)
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return ops;
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}
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return NULL;
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}
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static bool klp_is_module(struct klp_object *obj)
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{
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return obj->name;
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}
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static bool klp_is_object_loaded(struct klp_object *obj)
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{
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return !obj->name || obj->mod;
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}
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/* sets obj->mod if object is not vmlinux and module is found */
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static void klp_find_object_module(struct klp_object *obj)
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{
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struct module *mod;
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if (!klp_is_module(obj))
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return;
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mutex_lock(&module_mutex);
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/*
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* We do not want to block removal of patched modules and therefore
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* we do not take a reference here. The patches are removed by
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* a going module handler instead.
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*/
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mod = find_module(obj->name);
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/*
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* Do not mess work of the module coming and going notifiers.
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* Note that the patch might still be needed before the going handler
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* is called. Module functions can be called even in the GOING state
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* until mod->exit() finishes. This is especially important for
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* patches that modify semantic of the functions.
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*/
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if (mod && mod->klp_alive)
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obj->mod = mod;
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mutex_unlock(&module_mutex);
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}
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/* klp_mutex must be held by caller */
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static bool klp_is_patch_registered(struct klp_patch *patch)
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{
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struct klp_patch *mypatch;
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list_for_each_entry(mypatch, &klp_patches, list)
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if (mypatch == patch)
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return true;
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return false;
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}
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static bool klp_initialized(void)
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{
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return !!klp_root_kobj;
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}
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struct klp_find_arg {
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const char *objname;
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const char *name;
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unsigned long addr;
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/*
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* If count == 0, the symbol was not found. If count == 1, a unique
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* match was found and addr is set. If count > 1, there is
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* unresolvable ambiguity among "count" number of symbols with the same
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* name in the same object.
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*/
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unsigned long count;
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};
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static int klp_find_callback(void *data, const char *name,
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struct module *mod, unsigned long addr)
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{
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struct klp_find_arg *args = data;
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if ((mod && !args->objname) || (!mod && args->objname))
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return 0;
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if (strcmp(args->name, name))
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return 0;
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if (args->objname && strcmp(args->objname, mod->name))
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return 0;
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/*
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* args->addr might be overwritten if another match is found
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* but klp_find_object_symbol() handles this and only returns the
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* addr if count == 1.
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*/
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args->addr = addr;
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args->count++;
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return 0;
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}
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static int klp_find_object_symbol(const char *objname, const char *name,
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unsigned long *addr)
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{
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struct klp_find_arg args = {
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.objname = objname,
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.name = name,
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.addr = 0,
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.count = 0
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};
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mutex_lock(&module_mutex);
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kallsyms_on_each_symbol(klp_find_callback, &args);
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mutex_unlock(&module_mutex);
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if (args.count == 0)
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pr_err("symbol '%s' not found in symbol table\n", name);
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else if (args.count > 1)
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pr_err("unresolvable ambiguity (%lu matches) on symbol '%s' in object '%s'\n",
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args.count, name, objname);
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else {
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*addr = args.addr;
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return 0;
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}
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*addr = 0;
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return -EINVAL;
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}
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struct klp_verify_args {
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const char *name;
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const unsigned long addr;
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};
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static int klp_verify_callback(void *data, const char *name,
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struct module *mod, unsigned long addr)
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{
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struct klp_verify_args *args = data;
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if (!mod &&
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!strcmp(args->name, name) &&
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args->addr == addr)
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return 1;
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return 0;
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}
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static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr)
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{
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struct klp_verify_args args = {
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.name = name,
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.addr = addr,
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};
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int ret;
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mutex_lock(&module_mutex);
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ret = kallsyms_on_each_symbol(klp_verify_callback, &args);
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mutex_unlock(&module_mutex);
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if (!ret) {
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pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",
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name, addr);
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return -EINVAL;
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}
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return 0;
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}
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static int klp_find_verify_func_addr(struct klp_object *obj,
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struct klp_func *func)
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{
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int ret;
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#if defined(CONFIG_RANDOMIZE_BASE)
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/* If KASLR has been enabled, adjust old_addr accordingly */
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if (kaslr_enabled() && func->old_addr)
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func->old_addr += kaslr_offset();
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#endif
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if (!func->old_addr || klp_is_module(obj))
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ret = klp_find_object_symbol(obj->name, func->old_name,
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&func->old_addr);
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else
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ret = klp_verify_vmlinux_symbol(func->old_name,
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func->old_addr);
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return ret;
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}
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/*
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* external symbols are located outside the parent object (where the parent
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* object is either vmlinux or the kmod being patched).
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*/
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static int klp_find_external_symbol(struct module *pmod, const char *name,
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unsigned long *addr)
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{
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const struct kernel_symbol *sym;
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/* first, check if it's an exported symbol */
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preempt_disable();
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sym = find_symbol(name, NULL, NULL, true, true);
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if (sym) {
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*addr = sym->value;
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preempt_enable();
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return 0;
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}
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preempt_enable();
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/* otherwise check if it's in another .o within the patch module */
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return klp_find_object_symbol(pmod->name, name, addr);
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}
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static int klp_write_object_relocations(struct module *pmod,
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struct klp_object *obj)
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{
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int ret;
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struct klp_reloc *reloc;
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if (WARN_ON(!klp_is_object_loaded(obj)))
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return -EINVAL;
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if (WARN_ON(!obj->relocs))
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return -EINVAL;
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for (reloc = obj->relocs; reloc->name; reloc++) {
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if (!klp_is_module(obj)) {
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ret = klp_verify_vmlinux_symbol(reloc->name,
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reloc->val);
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if (ret)
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return ret;
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} else {
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/* module, reloc->val needs to be discovered */
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if (reloc->external)
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ret = klp_find_external_symbol(pmod,
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reloc->name,
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&reloc->val);
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else
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ret = klp_find_object_symbol(obj->mod->name,
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reloc->name,
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&reloc->val);
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if (ret)
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return ret;
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}
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ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc,
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reloc->val + reloc->addend);
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if (ret) {
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pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n",
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reloc->name, reloc->val, ret);
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return ret;
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}
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}
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return 0;
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}
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static void notrace klp_ftrace_handler(unsigned long ip,
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unsigned long parent_ip,
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struct ftrace_ops *fops,
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struct pt_regs *regs)
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{
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struct klp_ops *ops;
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struct klp_func *func;
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ops = container_of(fops, struct klp_ops, fops);
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rcu_read_lock();
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func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
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stack_node);
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if (WARN_ON_ONCE(!func))
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goto unlock;
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klp_arch_set_pc(regs, (unsigned long)func->new_func);
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unlock:
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rcu_read_unlock();
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}
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static void klp_disable_func(struct klp_func *func)
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{
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struct klp_ops *ops;
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if (WARN_ON(func->state != KLP_ENABLED))
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return;
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if (WARN_ON(!func->old_addr))
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return;
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ops = klp_find_ops(func->old_addr);
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if (WARN_ON(!ops))
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return;
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if (list_is_singular(&ops->func_stack)) {
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WARN_ON(unregister_ftrace_function(&ops->fops));
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WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0));
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list_del_rcu(&func->stack_node);
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list_del(&ops->node);
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kfree(ops);
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} else {
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list_del_rcu(&func->stack_node);
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}
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func->state = KLP_DISABLED;
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}
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static int klp_enable_func(struct klp_func *func)
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{
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struct klp_ops *ops;
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int ret;
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if (WARN_ON(!func->old_addr))
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return -EINVAL;
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if (WARN_ON(func->state != KLP_DISABLED))
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return -EINVAL;
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ops = klp_find_ops(func->old_addr);
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if (!ops) {
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ops = kzalloc(sizeof(*ops), GFP_KERNEL);
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if (!ops)
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return -ENOMEM;
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ops->fops.func = klp_ftrace_handler;
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ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS |
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FTRACE_OPS_FL_DYNAMIC |
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FTRACE_OPS_FL_IPMODIFY;
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list_add(&ops->node, &klp_ops);
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INIT_LIST_HEAD(&ops->func_stack);
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list_add_rcu(&func->stack_node, &ops->func_stack);
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ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 0, 0);
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if (ret) {
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pr_err("failed to set ftrace filter for function '%s' (%d)\n",
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func->old_name, ret);
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goto err;
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}
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ret = register_ftrace_function(&ops->fops);
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if (ret) {
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pr_err("failed to register ftrace handler for function '%s' (%d)\n",
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func->old_name, ret);
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ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0);
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goto err;
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}
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} else {
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list_add_rcu(&func->stack_node, &ops->func_stack);
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}
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func->state = KLP_ENABLED;
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return 0;
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err:
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list_del_rcu(&func->stack_node);
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list_del(&ops->node);
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kfree(ops);
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return ret;
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}
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static void klp_disable_object(struct klp_object *obj)
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{
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struct klp_func *func;
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klp_for_each_func(obj, func)
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if (func->state == KLP_ENABLED)
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klp_disable_func(func);
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obj->state = KLP_DISABLED;
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}
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static int klp_enable_object(struct klp_object *obj)
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{
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struct klp_func *func;
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int ret;
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if (WARN_ON(obj->state != KLP_DISABLED))
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return -EINVAL;
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if (WARN_ON(!klp_is_object_loaded(obj)))
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return -EINVAL;
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klp_for_each_func(obj, func) {
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ret = klp_enable_func(func);
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if (ret) {
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klp_disable_object(obj);
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return ret;
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}
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}
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obj->state = KLP_ENABLED;
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return 0;
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}
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static int __klp_disable_patch(struct klp_patch *patch)
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{
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struct klp_object *obj;
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|
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/* enforce stacking: only the last enabled patch can be disabled */
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if (!list_is_last(&patch->list, &klp_patches) &&
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list_next_entry(patch, list)->state == KLP_ENABLED)
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return -EBUSY;
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pr_notice("disabling patch '%s'\n", patch->mod->name);
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klp_for_each_object(patch, obj) {
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if (obj->state == KLP_ENABLED)
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klp_disable_object(obj);
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}
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|
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patch->state = KLP_DISABLED;
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|
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return 0;
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}
|
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|
|
/**
|
|
* klp_disable_patch() - disables a registered patch
|
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* @patch: The registered, enabled patch to be disabled
|
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*
|
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* Unregisters the patched functions from ftrace.
|
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*
|
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* Return: 0 on success, otherwise error
|
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*/
|
|
int klp_disable_patch(struct klp_patch *patch)
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{
|
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int ret;
|
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|
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mutex_lock(&klp_mutex);
|
|
|
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if (!klp_is_patch_registered(patch)) {
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ret = -EINVAL;
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goto err;
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}
|
|
|
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if (patch->state == KLP_DISABLED) {
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ret = -EINVAL;
|
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goto err;
|
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}
|
|
|
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ret = __klp_disable_patch(patch);
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|
|
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err:
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mutex_unlock(&klp_mutex);
|
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return ret;
|
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}
|
|
EXPORT_SYMBOL_GPL(klp_disable_patch);
|
|
|
|
static int __klp_enable_patch(struct klp_patch *patch)
|
|
{
|
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struct klp_object *obj;
|
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int ret;
|
|
|
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if (WARN_ON(patch->state != KLP_DISABLED))
|
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return -EINVAL;
|
|
|
|
/* enforce stacking: only the first disabled patch can be enabled */
|
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if (patch->list.prev != &klp_patches &&
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list_prev_entry(patch, list)->state == KLP_DISABLED)
|
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return -EBUSY;
|
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|
|
pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n");
|
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add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK);
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|
|
pr_notice("enabling patch '%s'\n", patch->mod->name);
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|
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klp_for_each_object(patch, obj) {
|
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if (!klp_is_object_loaded(obj))
|
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continue;
|
|
|
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ret = klp_enable_object(obj);
|
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if (ret)
|
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goto unregister;
|
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}
|
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|
|
patch->state = KLP_ENABLED;
|
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|
|
return 0;
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|
|
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_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;
|
|
|
|
return kobject_init_and_add(&func->kobj, &klp_ktype_func,
|
|
&obj->kobj, "%s", 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;
|
|
}
|
|
|
|
klp_for_each_func(obj, 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;
|
|
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 (!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 int 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) {
|
|
pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
|
|
pmod->name, mod->name, ret);
|
|
return ret;
|
|
}
|
|
|
|
if (patch->state == KLP_DISABLED)
|
|
return 0;
|
|
|
|
pr_notice("applying patch '%s' to loading module '%s'\n",
|
|
pmod->name, mod->name);
|
|
|
|
ret = klp_enable_object(obj);
|
|
if (ret)
|
|
pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
|
|
pmod->name, mod->name, ret);
|
|
return 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)
|
|
{
|
|
int ret;
|
|
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);
|
|
|
|
/*
|
|
* Each module has to know that the notifier has been called.
|
|
* We never know what module will get patched by a new patch.
|
|
*/
|
|
if (action == MODULE_STATE_COMING)
|
|
mod->klp_alive = true;
|
|
else /* MODULE_STATE_GOING */
|
|
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 (action == MODULE_STATE_COMING) {
|
|
obj->mod = mod;
|
|
ret = klp_module_notify_coming(patch, obj);
|
|
if (ret) {
|
|
obj->mod = NULL;
|
|
pr_warn("patch '%s' is in an inconsistent state!\n",
|
|
patch->mod->name);
|
|
}
|
|
} 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 __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;
|
|
}
|
|
|
|
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);
|