![Jessica Yu](/assets/img/avatar_default.png)
Add ro_after_init support for modules by adding a new page-aligned section in the module layout (after rodata) for ro_after_init data and enabling RO protection for that section after module init runs. Signed-off-by: Jessica Yu <jeyu@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
1060 lines
24 KiB
C
1060 lines
24 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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#include <linux/elf.h>
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#include <linux/moduleloader.h>
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#include <asm/cacheflush.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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* klp_module_going() 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 klp_module_coming() and klp_module_going().
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* Note that the patch might still be needed before klp_module_going()
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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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unsigned long count;
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unsigned long pos;
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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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args->addr = addr;
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args->count++;
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/*
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* Finish the search when the symbol is found for the desired position
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* or the position is not defined for a non-unique symbol.
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*/
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if ((args->pos && (args->count == args->pos)) ||
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(!args->pos && (args->count > 1)))
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return 1;
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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 sympos, 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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.pos = sympos,
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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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/*
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* Ensure an address was found. If sympos is 0, ensure symbol is unique;
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* otherwise ensure the symbol position count matches sympos.
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*/
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if (args.addr == 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 && sympos == 0) {
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pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n",
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name, objname);
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} else if (sympos != args.count && sympos > 0) {
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pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n",
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sympos, name, objname ? objname : "vmlinux");
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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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static int klp_resolve_symbols(Elf_Shdr *relasec, struct module *pmod)
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{
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int i, cnt, vmlinux, ret;
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char objname[MODULE_NAME_LEN];
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char symname[KSYM_NAME_LEN];
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char *strtab = pmod->core_kallsyms.strtab;
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Elf_Rela *relas;
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Elf_Sym *sym;
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unsigned long sympos, addr;
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/*
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* Since the field widths for objname and symname in the sscanf()
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* call are hard-coded and correspond to MODULE_NAME_LEN and
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* KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN
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* and KSYM_NAME_LEN have the values we expect them to have.
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*
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* Because the value of MODULE_NAME_LEN can differ among architectures,
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* we use the smallest/strictest upper bound possible (56, based on
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* the current definition of MODULE_NAME_LEN) to prevent overflows.
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*/
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BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128);
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relas = (Elf_Rela *) relasec->sh_addr;
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/* For each rela in this klp relocation section */
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for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) {
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sym = pmod->core_kallsyms.symtab + ELF_R_SYM(relas[i].r_info);
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if (sym->st_shndx != SHN_LIVEPATCH) {
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pr_err("symbol %s is not marked as a livepatch symbol",
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strtab + sym->st_name);
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return -EINVAL;
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}
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/* Format: .klp.sym.objname.symname,sympos */
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cnt = sscanf(strtab + sym->st_name,
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".klp.sym.%55[^.].%127[^,],%lu",
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objname, symname, &sympos);
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if (cnt != 3) {
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pr_err("symbol %s has an incorrectly formatted name",
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strtab + sym->st_name);
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return -EINVAL;
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}
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/* klp_find_object_symbol() treats a NULL objname as vmlinux */
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vmlinux = !strcmp(objname, "vmlinux");
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ret = klp_find_object_symbol(vmlinux ? NULL : objname,
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symname, sympos, &addr);
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if (ret)
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return ret;
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sym->st_value = addr;
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}
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return 0;
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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 i, cnt, ret = 0;
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const char *objname, *secname;
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char sec_objname[MODULE_NAME_LEN];
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Elf_Shdr *sec;
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if (WARN_ON(!klp_is_object_loaded(obj)))
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return -EINVAL;
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objname = klp_is_module(obj) ? obj->name : "vmlinux";
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module_disable_ro(pmod);
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/* For each klp relocation section */
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for (i = 1; i < pmod->klp_info->hdr.e_shnum; i++) {
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sec = pmod->klp_info->sechdrs + i;
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secname = pmod->klp_info->secstrings + sec->sh_name;
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if (!(sec->sh_flags & SHF_RELA_LIVEPATCH))
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continue;
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/*
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* Format: .klp.rela.sec_objname.section_name
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* See comment in klp_resolve_symbols() for an explanation
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* of the selected field width value.
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*/
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cnt = sscanf(secname, ".klp.rela.%55[^.]", sec_objname);
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if (cnt != 1) {
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pr_err("section %s has an incorrectly formatted name",
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secname);
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ret = -EINVAL;
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break;
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}
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if (strcmp(objname, sec_objname))
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continue;
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ret = klp_resolve_symbols(sec, pmod);
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if (ret)
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break;
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ret = apply_relocate_add(pmod->klp_info->sechdrs,
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pmod->core_kallsyms.strtab,
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pmod->klp_info->symndx, i, pmod);
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if (ret)
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break;
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}
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module_enable_ro(pmod, true);
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return ret;
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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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/*
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* Convert a function address into the appropriate ftrace location.
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*
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* Usually this is just the address of the function, but on some architectures
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* it's more complicated so allow them to provide a custom behaviour.
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*/
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#ifndef klp_get_ftrace_location
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static unsigned long klp_get_ftrace_location(unsigned long faddr)
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{
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return faddr;
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}
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#endif
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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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unsigned long ftrace_loc;
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ftrace_loc = klp_get_ftrace_location(func->old_addr);
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if (WARN_ON(!ftrace_loc))
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return;
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WARN_ON(unregister_ftrace_function(&ops->fops));
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WARN_ON(ftrace_set_filter_ip(&ops->fops, ftrace_loc, 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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unsigned long ftrace_loc;
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ftrace_loc = klp_get_ftrace_location(func->old_addr);
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if (!ftrace_loc) {
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pr_err("failed to find location for function '%s'\n",
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func->old_name);
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return -EINVAL;
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}
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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, ftrace_loc, 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, ftrace_loc, 1, 0);
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goto err;
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}
|
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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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|
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func->state = KLP_ENABLED;
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|
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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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|
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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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|
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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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|
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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;
|
|
|
|
if (WARN_ON(!klp_is_object_loaded(obj)))
|
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return -EINVAL;
|
|
|
|
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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}
|
|
}
|
|
obj->state = KLP_ENABLED;
|
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|
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return 0;
|
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}
|
|
|
|
static int __klp_disable_patch(struct klp_patch *patch)
|
|
{
|
|
struct klp_object *obj;
|
|
|
|
/* 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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|
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pr_notice("disabling 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 (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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}
|
|
|
|
/**
|
|
* 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)) {
|
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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)
|
|
{
|
|
if (!func->old_name || !func->new_func)
|
|
return -EINVAL;
|
|
|
|
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 (!patch || !patch->mod)
|
|
return -EINVAL;
|
|
|
|
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;
|
|
|
|
/*
|
|
* 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);
|