RepoMirrors
/
kpatch
mirror of https://github.com/dynup/kpatch
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
kpatch/kmod/patch/livepatch-patch-hook.c

607 lines
17 KiB
C
Raw Blame History

/*
* Copyright (C) 2013-2014 Josh Poimboeuf <jpoimboe@redhat.com>
* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA,
* 02110-1301, USA.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/version.h>
#include <generated/utsrelease.h>
#include <linux/livepatch.h>
#include "kpatch-patch.h"
#ifndef UTS_UBUNTU_RELEASE_ABI
#define UTS_UBUNTU_RELEASE_ABI 0
#endif
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 7, 0) || \
defined(RHEL_RELEASE_CODE)
#define HAVE_ELF_RELOCS
#endif
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 5, 0) || \
(LINUX_VERSION_CODE >= KERNEL_VERSION(4, 4, 0) && \
UTS_UBUNTU_RELEASE_ABI >= 7) || \
defined(RHEL_RELEASE_CODE)
#define HAVE_SYMPOS
#endif
#ifdef RHEL_RELEASE_CODE
# if RHEL_RELEASE_CODE <= RHEL_RELEASE_VERSION(7, 5)
# define HAVE_IMMEDIATE
# endif
#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(4, 12, 0) && \
LINUX_VERSION_CODE <= KERNEL_VERSION(4, 15, 0))
# define HAVE_IMMEDIATE
#endif
#ifdef RHEL_RELEASE_CODE
# if RHEL_RELEASE_CODE >= RHEL_RELEASE_VERSION(7, 5)
# define HAVE_CALLBACKS
# endif
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 15, 0)
# define HAVE_CALLBACKS
#endif
#ifdef RHEL_RELEASE_CODE
# if (RHEL_RELEASE_CODE >= RHEL_RELEASE_VERSION(7, 8) && \
RHEL_RELEASE_CODE < RHEL_RELEASE_VERSION(8, 0)) || \
RHEL_RELEASE_CODE >= RHEL_RELEASE_VERSION(8, 2)
# define HAVE_SIMPLE_ENABLE
# endif
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 1, 0)
# define HAVE_SIMPLE_ENABLE
#endif
#ifdef RHEL_RELEASE_CODE
# if RHEL_RELEASE_CODE >= RHEL_RELEASE_VERSION(8, 2)
# define HAVE_KLP_REPLACE
# endif
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 1, 0)
# define HAVE_KLP_REPLACE
#endif
#ifndef KLP_REPLACE_ENABLE
#define KLP_REPLACE_ENABLE true
#endif
/*
* There are quite a few similar structures at play in this file:
* - livepatch.h structs prefixed with klp_*
* - kpatch-patch.h structs prefixed with kpatch_patch_*
* - local scaffolding structs prefixed with patch_*
*
* The naming of the struct variables follows this convention:
* - livepatch struct being with "l" (e.g. lfunc)
* - kpatch_patch structs being with "k" (e.g. kfunc)
* - local scaffolding structs have no prefix (e.g. func)
*
* The program reads in kpatch_patch structures, arranges them into the
* scaffold structures, then creates a livepatch structure suitable for
* registration with the livepatch kernel API. The scaffold structs only
* exist to allow the construction of the klp_patch struct. Once that is
* done, the scaffold structs are no longer needed.
*/
/*
* lpatch is the kernel data structure that will be created on patch
* init, registered with the livepatch API on init, and finally
* unregistered when the patch exits. Its struct klp_object *objs
* member must be dynamically allocated according to the number of
* target objects it will be patching.
*/
static struct klp_patch *lpatch;
static LIST_HEAD(patch_objects);
static int patch_objects_nr;
/**
* struct patch_object - scaffolding structure tracking patch target objects
* @list: list of patch_object (threaded onto patch_objects)
* @funcs: list of patch_func associated with this object
* @relocs: list of patch_reloc associated with this object
* @callbacks: kernel struct of object callbacks
* @name: patch target object name (NULL for vmlinux)
* @funcs_nr: count of kpatch_patch_func added to @funcs
* @relocs_nr: count of patch_reloc added to @relocs
*/
struct patch_object {
struct list_head list;
struct list_head funcs;
struct list_head relocs;
#ifdef HAVE_CALLBACKS
struct klp_callbacks callbacks;
#endif
const char *name;
int funcs_nr, relocs_nr;
};
/**
* struct patch_func - scaffolding structure for kpatch_patch_func
* @list: list of patch_func (threaded onto patch_object.funcs)
* @kfunc: array of kpatch_patch_func
*/
struct patch_func {
struct list_head list;
struct kpatch_patch_func *kfunc;
};
/**
* struct patch_reloc - scaffolding structure for kpatch_patch_dynrela
* @list: list of patch_reloc (threaded onto patch_object.relocs)
* @kdynrela: array of kpatch_patch_dynrela
*/
struct patch_reloc {
struct list_head list;
struct kpatch_patch_dynrela *kdynrela;
};
/**
* patch_alloc_new_object() - creates and initializes a new patch_object
* @name: target object name
*
* Return: pointer to new patch_object, NULL on failure.
*
* Does not check for previously created patch_objects with the same
* name. Updates patch_objects_nr and threads new data structure onto
* the patch_objects list.
*/
static struct patch_object *patch_alloc_new_object(const char *name)
{
struct patch_object *object;
object = kzalloc(sizeof(*object), GFP_KERNEL);
if (!object)
return NULL;
INIT_LIST_HEAD(&object->funcs);
#ifndef HAVE_ELF_RELOCS
INIT_LIST_HEAD(&object->relocs);
#endif
if (strcmp(name, "vmlinux"))
object->name = name;
list_add(&object->list, &patch_objects);
patch_objects_nr++;
return object;
}
/**
* patch_find_object_by_name() - find or create a patch_object with a
* given name
* @name: target object name
*
* Return: pointer to patch_object, NULL on failure.
*
* Searches the patch_objects list for an already created instance with
* @name, otherwise tries to create it via patch_alloc_new_object()
*/
static struct patch_object *patch_find_object_by_name(const char *name)
{
struct patch_object *object;
list_for_each_entry(object, &patch_objects, list)
if ((!strcmp(name, "vmlinux") && !object->name) ||
(object->name && !strcmp(object->name, name)))
return object;
return patch_alloc_new_object(name);
}
/**
* patch_add_func_to_object() - create scaffolding from kpatch_patch_func data
*
* @kfunc: Individual kpatch_patch_func pointer
*
* Return: 0 on success, -ENOMEM on failure.
*
* Builds scaffolding data structures from .kpatch.funcs section's array
* of kpatch_patch_func structures. Updates the associated
* patch_object's funcs_nr count.
*/
static int patch_add_func_to_object(struct kpatch_patch_func *kfunc)
{
struct patch_func *func;
struct patch_object *object;
func = kzalloc(sizeof(*func), GFP_KERNEL);
if (!func)
return -ENOMEM;
INIT_LIST_HEAD(&func->list);
func->kfunc = kfunc;
object = patch_find_object_by_name(kfunc->objname);
if (!object) {
kfree(func);
return -ENOMEM;
}
list_add(&func->list, &object->funcs);
object->funcs_nr++;
return 0;
}
#ifndef HAVE_ELF_RELOCS
/**
* patch_add_reloc_to_object() - create scaffolding from kpatch_patch_dynrela data
*
* @kdynrela: Individual kpatch_patch_dynrela pointer
*
* Return: 0 on success, -ENOMEM on failure.
*
* Builds scaffolding data structures from .kpatch.dynrelas section's array
* of kpatch_patch_dynrela structures. Updates the associated
* patch_object's relocs_nr count.
*/
static int patch_add_reloc_to_object(struct kpatch_patch_dynrela *kdynrela)
{
struct patch_reloc *reloc;
struct patch_object *object;
reloc = kzalloc(sizeof(*reloc), GFP_KERNEL);
if (!reloc)
return -ENOMEM;
INIT_LIST_HEAD(&reloc->list);
reloc->kdynrela = kdynrela;
object = patch_find_object_by_name(kdynrela->objname);
if (!object) {
kfree(reloc);
return -ENOMEM;
}
list_add(&reloc->list, &object->relocs);
object->relocs_nr++;
return 0;
}
#endif
/**
* patch_free_scaffold() - tear down the temporary kpatch scaffolding
*/
static void patch_free_scaffold(void) {
struct patch_func *func, *safefunc;
struct patch_object *object, *safeobject;
#ifndef HAVE_ELF_RELOCS
struct patch_reloc *reloc, *safereloc;
#endif
list_for_each_entry_safe(object, safeobject, &patch_objects, list) {
list_for_each_entry_safe(func, safefunc,
&object->funcs, list) {
list_del(&func->list);
kfree(func);
}
#ifndef HAVE_ELF_RELOCS
list_for_each_entry_safe(reloc, safereloc,
&object->relocs, list) {
list_del(&reloc->list);
kfree(reloc);
}
#endif
list_del(&object->list);
kfree(object);
}
}
/**
* patch_free_livepatch() - release the klp_patch and friends
*/
static void patch_free_livepatch(struct klp_patch *patch)
{
struct klp_object *object;
if (patch) {
for (object = patch->objs; object && object->funcs; object++) {
if (object->funcs)
kfree(object->funcs);
#ifndef HAVE_ELF_RELOCS
if (object->relocs)
kfree(object->relocs);
#endif
}
if (patch->objs)
kfree(patch->objs);
kfree(patch);
}
}
/* Defined by kpatch.lds.S */
extern struct kpatch_pre_patch_callback __kpatch_callbacks_pre_patch[], __kpatch_callbacks_pre_patch_end[];
extern struct kpatch_post_patch_callback __kpatch_callbacks_post_patch[], __kpatch_callbacks_post_patch_end[];
extern struct kpatch_pre_unpatch_callback __kpatch_callbacks_pre_unpatch[], __kpatch_callbacks_pre_unpatch_end[];
extern struct kpatch_post_unpatch_callback __kpatch_callbacks_post_unpatch[], __kpatch_callbacks_post_unpatch_end[];
#ifdef HAVE_CALLBACKS
/**
* add_callbacks_to_patch_objects() - create patch_objects that have callbacks
*
* Return: 0 on success, -ENOMEM or -EINVAL on failure
*
* Iterates through all kpatch pre/post-(un)patch callback data
* structures and creates scaffolding patch_objects for them.
*/
static int add_callbacks_to_patch_objects(void)
{
struct kpatch_pre_patch_callback *p_pre_patch_callback;
struct kpatch_post_patch_callback *p_post_patch_callback;
struct kpatch_pre_unpatch_callback *p_pre_unpatch_callback;
struct kpatch_post_unpatch_callback *p_post_unpatch_callback;
struct patch_object *object;
for (p_pre_patch_callback = __kpatch_callbacks_pre_patch;
p_pre_patch_callback < __kpatch_callbacks_pre_patch_end;
p_pre_patch_callback++) {
object = patch_find_object_by_name(p_pre_patch_callback->objname);
if (!object)
return -ENOMEM;
if (object->callbacks.pre_patch) {
pr_err("extra pre-patch callback for object: %s\n",
object->name ? object->name : "vmlinux");
return -EINVAL;
}
object->callbacks.pre_patch = (int (*)(struct klp_object *))
p_pre_patch_callback->callback;
}
for (p_post_patch_callback = __kpatch_callbacks_post_patch;
p_post_patch_callback < __kpatch_callbacks_post_patch_end;
p_post_patch_callback++) {
object = patch_find_object_by_name(p_post_patch_callback->objname);
if (!object)
return -ENOMEM;
if (object->callbacks.post_patch) {
pr_err("extra post-patch callback for object: %s\n",
object->name ? object->name : "vmlinux");
return -EINVAL;
}
object->callbacks.post_patch = (void (*)(struct klp_object *))
p_post_patch_callback->callback;
}
for (p_pre_unpatch_callback = __kpatch_callbacks_pre_unpatch;
p_pre_unpatch_callback < __kpatch_callbacks_pre_unpatch_end;
p_pre_unpatch_callback++) {
object = patch_find_object_by_name(p_pre_unpatch_callback->objname);
if (!object)
return -ENOMEM;
if (object->callbacks.pre_unpatch) {
pr_err("extra pre-unpatch callback for object: %s\n",
object->name ? object->name : "vmlinux");
return -EINVAL;
}
object->callbacks.pre_unpatch = (void (*)(struct klp_object *))
p_pre_unpatch_callback->callback;
}
for (p_post_unpatch_callback = __kpatch_callbacks_post_unpatch;
p_post_unpatch_callback < __kpatch_callbacks_post_unpatch_end;
p_post_unpatch_callback++) {
object = patch_find_object_by_name(p_post_unpatch_callback->objname);
if (!object)
return -ENOMEM;
if (object->callbacks.post_unpatch) {
pr_err("extra post-unpatch callback for object: %s\n",
object->name ? object->name : "vmlinux");
return -EINVAL;
}
object->callbacks.post_unpatch = (void (*)(struct klp_object *))
p_post_unpatch_callback->callback;
}
return 0;
}
#else /* HAVE_CALLBACKS */
static inline int add_callbacks_to_patch_objects(void)
{
if (__kpatch_callbacks_pre_patch !=
__kpatch_callbacks_pre_patch_end ||
__kpatch_callbacks_post_patch !=
__kpatch_callbacks_post_patch_end ||
__kpatch_callbacks_pre_unpatch !=
__kpatch_callbacks_pre_unpatch_end ||
__kpatch_callbacks_post_unpatch !=
__kpatch_callbacks_post_unpatch_end) {
pr_err("patch callbacks are not supported\n");
return -EINVAL;
}
return 0;
}
#endif /* HAVE_CALLBACKS */
/* Defined by kpatch.lds.S */
extern struct kpatch_patch_func __kpatch_funcs[], __kpatch_funcs_end[];
#ifndef HAVE_ELF_RELOCS
extern struct kpatch_patch_dynrela __kpatch_dynrelas[], __kpatch_dynrelas_end[];
#endif
static int __init patch_init(void)
{
struct kpatch_patch_func *kfunc;
struct klp_object *lobjects, *lobject;
struct klp_func *lfuncs, *lfunc;
struct patch_object *object;
struct patch_func *func;
int ret = 0, i, j;
#ifndef HAVE_ELF_RELOCS
struct kpatch_patch_dynrela *kdynrela;
struct patch_reloc *reloc;
struct klp_reloc *lrelocs, *lreloc;
#endif
/*
* Step 1 - read from output.o, create temporary scaffolding
* data-structures
*/
/* organize functions and relocs by object in scaffold */
for (kfunc = __kpatch_funcs;
kfunc != __kpatch_funcs_end;
kfunc++) {
ret = patch_add_func_to_object(kfunc);
if (ret)
goto out;
}
#ifndef HAVE_ELF_RELOCS
for (kdynrela = __kpatch_dynrelas;
kdynrela != __kpatch_dynrelas_end;
kdynrela++) {
ret = patch_add_reloc_to_object(kdynrela);
if (ret)
goto out;
}
#endif
ret = add_callbacks_to_patch_objects();
if (ret)
goto out;
/* past this point, only possible return code is -ENOMEM */
ret = -ENOMEM;
/*
* Step 2 - create livepatch klp_patch and friends
*
* There are two dynamically allocated parts:
*
* klp_patch
* klp_object objs [patch_objects_nr] <= i
* klp_func funcs [object->funcs_nr] <= j
*/
/* allocate and fill livepatch structures */
lpatch = kzalloc(sizeof(*lpatch), GFP_KERNEL);
if (!lpatch)
goto out;
lobjects = kzalloc(sizeof(*lobjects) * (patch_objects_nr+1),
GFP_KERNEL);
if (!lobjects)
goto out;
lpatch->mod = THIS_MODULE;
lpatch->objs = lobjects;
#ifdef HAVE_KLP_REPLACE
lpatch->replace = KLP_REPLACE_ENABLE;
#endif
#if defined(__powerpc64__) && defined(HAVE_IMMEDIATE)
lpatch->immediate = true;
#endif
i = 0;
list_for_each_entry(object, &patch_objects, list) {
lobject = &lobjects[i];
lobject->name = object->name;
lfuncs = kzalloc(sizeof(struct klp_func) *
(object->funcs_nr+1), GFP_KERNEL);
if (!lfuncs)
goto out;
lobject->funcs = lfuncs;
j = 0;
list_for_each_entry(func, &object->funcs, list) {
lfunc = &lfuncs[j];
lfunc->old_name = func->kfunc->name;
lfunc->new_func = (void *)func->kfunc->new_addr;
#ifdef HAVE_SYMPOS
lfunc->old_sympos = func->kfunc->sympos;
#else
lfunc->old_addr = func->kfunc->old_addr;
#endif
j++;
}
#ifndef HAVE_ELF_RELOCS
lrelocs = kzalloc(sizeof(struct klp_reloc) *
(object->relocs_nr+1), GFP_KERNEL);
if (!lrelocs)
goto out;
lobject->relocs = lrelocs;
j = 0;
list_for_each_entry(reloc, &object->relocs, list) {
lreloc = &lrelocs[j];
lreloc->loc = reloc->kdynrela->dest;
#ifdef HAVE_SYMPOS
lreloc->sympos = reloc->kdynrela->sympos;
#else
lreloc->val = reloc->kdynrela->src;
#endif /* HAVE_SYMPOS */
lreloc->type = reloc->kdynrela->type;
lreloc->name = reloc->kdynrela->name;
lreloc->addend = reloc->kdynrela->addend;
lreloc->external = reloc->kdynrela->external;
j++;
}
#endif /* HAVE_ELF_RELOCS */
#ifdef HAVE_CALLBACKS
lobject->callbacks = object->callbacks;
#endif
i++;
}
/*
* Step 3 - throw away scaffolding
*/
/*
* Once the patch structure that the live patching API expects
* has been built, we can release the scaffold structure.
*/
patch_free_scaffold();
#ifndef HAVE_SIMPLE_ENABLE
ret = klp_register_patch(lpatch);
if (ret) {
patch_free_livepatch(lpatch);
return ret;
}
#endif
ret = klp_enable_patch(lpatch);
if (ret) {
#ifndef HAVE_SIMPLE_ENABLE
WARN_ON(klp_unregister_patch(lpatch));
#endif
patch_free_livepatch(lpatch);
return ret;
}
return 0;
out:
patch_free_livepatch(lpatch);
patch_free_scaffold();
return ret;
}
static void __exit patch_exit(void)
{
#ifndef HAVE_SIMPLE_ENABLE
WARN_ON(klp_unregister_patch(lpatch));
#endif
patch_free_livepatch(lpatch);
}
module_init(patch_init);
module_exit(patch_exit);
MODULE_LICENSE("GPL");
MODULE_INFO(livepatch, "Y");
Reference in New Issue View Git Blame Copy Permalink