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module: Move livepatch support to a separate file 

JIRA: https://issues.redhat.com/browse/RHEL-28063

Conflicts:
   Source and patch diff due to RHEL9 commit 6e0e3815
   applied out of order with respect to upstream.
   Carried the modification main.c to livepatch.c;
   just comments, no functional changes.

commit 1be9473e31ab87ad1b6ecf9fd11df461930ede85
Author: Aaron Tomlin <atomlin@redhat.com>
Date:   Tue Mar 22 14:03:34 2022 +0000

    module: Move livepatch support to a separate file

    No functional change.

    This patch migrates livepatch support (i.e. used during module
    add/or load and remove/or deletion) from core module code into
    kernel/module/livepatch.c. At the moment it contains code to
    persist Elf information about a given livepatch module, only.
    The new file was added to MAINTAINERS.

    Reviewed-by: Petr Mladek <pmladek@suse.com>
    Tested-by: Petr Mladek <pmladek@suse.com>
    Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
    Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

Signed-off-by: Donald Dutile <ddutile@redhat.com>
This commit is contained in:
Donald Dutile 2024-05-09 01:53:40 -04:00
parent 4469abdac2
commit 15862b318b
6 changed files with 112 additions and 99 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
MAINTAINERS
View File

@ -11169,6 +11169,7 @@ F: arch/s390/include/asm/livepatch.h
F: arch/x86/include/asm/livepatch.h
F: include/linux/livepatch.h
F: kernel/livepatch/
F: kernel/module/livepatch.c
F: lib/livepatch/
F: samples/livepatch/
F: tools/testing/selftests/livepatch/

11
include/linux/module.h
View File

@ -660,17 +660,14 @@ static inline bool module_requested_async_probing(struct module *module)
return module && module->async_probe_requested;
}
static inline bool is_livepatch_module(struct module *mod)
{
#ifdef CONFIG_LIVEPATCH
static inline bool is_livepatch_module(struct module *mod)
{
return mod->klp;
}
#else /* !CONFIG_LIVEPATCH */
static inline bool is_livepatch_module(struct module *mod)
{
#else
return false;
#endif
}
#endif /* CONFIG_LIVEPATCH */
bool is_module_sig_enforced(void);
void set_module_sig_enforced(void);

1
kernel/module/Makefile
View File

@ -10,3 +10,4 @@ KCOV_INSTRUMENT_module.o := n
obj-y += main.o
obj-$(CONFIG_MODULE_DECOMPRESS) += decompress.o
obj-$(CONFIG_MODULE_SIG) += signing.o
obj-$(CONFIG_LIVEPATCH) += livepatch.o

22
kernel/module/internal.h
View File

@ -57,6 +57,28 @@ struct load_info {
int mod_verify_sig(const void *mod, struct load_info *info);
#ifdef CONFIG_LIVEPATCH
int copy_module_elf(struct module *mod, struct load_info *info);
void free_module_elf(struct module *mod);
#else /* !CONFIG_LIVEPATCH */
static inline int copy_module_elf(struct module *mod, struct load_info *info)
{
return 0;
}
static inline void free_module_elf(struct module *mod) { }
#endif /* CONFIG_LIVEPATCH */
static inline bool set_livepatch_module(struct module *mod)
{
#ifdef CONFIG_LIVEPATCH
mod->klp = true;
return true;
#else
return false;
#endif
}
#ifdef CONFIG_MODULE_DECOMPRESS
int module_decompress(struct load_info *info, const void *buf, size_t size);
void module_decompress_cleanup(struct load_info *info);

74
kernel/module/livepatch.c Normal file
View File

@ -0,0 +1,74 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Module livepatch support
*
* Copyright (C) 2016 Jessica Yu <jeyu@redhat.com>
*/
#include <linux/module.h>
#include <linux/string.h>
#include <linux/slab.h>
#include "internal.h"
/*
* Persist ELF information about a module. Copy the ELF header,
* section header table, section string table, and symtab section
* index from info to mod->klp_info.
*/
int copy_module_elf(struct module *mod, struct load_info *info)
{
unsigned int size, symndx;
int ret;
size = sizeof(*mod->klp_info);
mod->klp_info = kmalloc(size, GFP_KERNEL);
if (!mod->klp_info)
return -ENOMEM;
/* ELF header */
size = sizeof(mod->klp_info->hdr);
memcpy(&mod->klp_info->hdr, info->hdr, size);
/* ELF section header table */
size = sizeof(*info->sechdrs) * info->hdr->e_shnum;
mod->klp_info->sechdrs = kmemdup(info->sechdrs, size, GFP_KERNEL);
if (!mod->klp_info->sechdrs) {
ret = -ENOMEM;
goto free_info;
}
/* ELF section name string table */
size = info->sechdrs[info->hdr->e_shstrndx].sh_size;
mod->klp_info->secstrings = kmemdup(info->secstrings, size, GFP_KERNEL);
if (!mod->klp_info->secstrings) {
ret = -ENOMEM;
goto free_sechdrs;
}
/* ELF symbol section index */
symndx = info->index.sym;
mod->klp_info->symndx = symndx;
/*
* For livepatch modules, core_kallsyms.symtab is a complete
* copy of the original symbol table. Adjust sh_addr to point
* to core_kallsyms.symtab since the copy of the symtab in module
* init memory is freed at the end of do_init_module().
*/
mod->klp_info->sechdrs[symndx].sh_addr = (unsigned long)mod->core_kallsyms.symtab;
return 0;
free_sechdrs:
kfree(mod->klp_info->sechdrs);
free_info:
kfree(mod->klp_info);
return ret;
}
void free_module_elf(struct module *mod)
{
kfree(mod->klp_info->sechdrs);
kfree(mod->klp_info->secstrings);
kfree(mod->klp_info);
}

102
kernel/module/main.c
View File

@ -2045,81 +2045,6 @@ static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
}
#endif /* CONFIG_STRICT_MODULE_RWX */
#ifdef CONFIG_LIVEPATCH
/*
* Persist ELF information about a module. Copy the ELF header,
* section header table, section string table, and symtab section
* index from info to mod->klp_info.
*/
static int copy_module_elf(struct module *mod, struct load_info *info)
{
unsigned int size, symndx;
int ret;
size = sizeof(*mod->klp_info);
mod->klp_info = kmalloc(size, GFP_KERNEL);
if (mod->klp_info == NULL)
return -ENOMEM;
/* ELF header */
size = sizeof(mod->klp_info->hdr);
memcpy(&mod->klp_info->hdr, info->hdr, size);
/* ELF section header table */
size = sizeof(*info->sechdrs) * info->hdr->e_shnum;
mod->klp_info->sechdrs = kmemdup(info->sechdrs, size, GFP_KERNEL);
if (mod->klp_info->sechdrs == NULL) {
ret = -ENOMEM;
goto free_info;
}
/* ELF section name string table */
size = info->sechdrs[info->hdr->e_shstrndx].sh_size;
mod->klp_info->secstrings = kmemdup(info->secstrings, size, GFP_KERNEL);
if (mod->klp_info->secstrings == NULL) {
ret = -ENOMEM;
goto free_sechdrs;
}
/* ELF symbol section index */
symndx = info->index.sym;
mod->klp_info->symndx = symndx;
/*
* For livepatch modules, core_kallsyms.symtab is a complete
* copy of the original symbol table. Adjust sh_addr to point
* to core_kallsyms.symtab since the copy of the symtab in module
* init memory is freed at the end of do_init_module().
*/
mod->klp_info->sechdrs[symndx].sh_addr = \
(unsigned long) mod->core_kallsyms.symtab;
return 0;
free_sechdrs:
kfree(mod->klp_info->sechdrs);
free_info:
kfree(mod->klp_info);
return ret;
}
static void free_module_elf(struct module *mod)
{
kfree(mod->klp_info->sechdrs);
kfree(mod->klp_info->secstrings);
kfree(mod->klp_info);
}
#else /* !CONFIG_LIVEPATCH */
static int copy_module_elf(struct module *mod, struct load_info *info)
{
return 0;
}
static void free_module_elf(struct module *mod)
{
}
#endif /* CONFIG_LIVEPATCH */
void __weak module_memfree(void *module_region)
{
/*
@ -3094,30 +3019,23 @@ static int copy_chunked_from_user(void *dst, const void __user *usrc, unsigned l
return 0;
}
#ifdef CONFIG_LIVEPATCH
static int check_modinfo_livepatch(struct module *mod, struct load_info *info)
{
if (get_modinfo(info, "livepatch")) {
mod->klp = true;
if (!get_modinfo(info, "livepatch"))
/* Nothing more to do */
return 0;
if (set_livepatch_module(mod)) {
add_taint_module(mod, TAINT_LIVEPATCH, LOCKDEP_STILL_OK);
pr_notice_once("%s: tainting kernel with TAINT_LIVEPATCH\n",
mod->name);
mod->name);
return 0;
}
return 0;
pr_err("%s: module is marked as livepatch module, but livepatch support is disabled",
mod->name);
return -ENOEXEC;
}
#else /* !CONFIG_LIVEPATCH */
static int check_modinfo_livepatch(struct module *mod, struct load_info *info)
{
if (get_modinfo(info, "livepatch")) {
pr_err("%s: module is marked as livepatch module, but livepatch support is disabled",
mod->name);
return -ENOEXEC;
}
return 0;
}
#endif /* CONFIG_LIVEPATCH */
static void check_modinfo_retpoline(struct module *mod, struct load_info *info)
{