[RFC PATCH 03/12] module: Move livepatch support to a separate file
From: Aaron Tomlin <hidden>
Date: 2021-12-28 21:30:54
Also in:
lkml
Subsystem:
live patching, module support, the rest · Maintainers:
Josh Poimboeuf, Jiri Kosina, Miroslav Benes, Petr Mladek, Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen, Linus Torvalds
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. Signed-off-by: Aaron Tomlin <redacted> --- kernel/module/Makefile | 1 + kernel/module/internal.h | 12 ++++++ kernel/module/livepatch.c | 75 +++++++++++++++++++++++++++++++++ kernel/module/main.c | 89 +-------------------------------------- 4 files changed, 89 insertions(+), 88 deletions(-) create mode 100644 kernel/module/livepatch.c
diff --git a/kernel/module/Makefile b/kernel/module/Makefile
index a9cf6e822075..47d70bb18da3 100644
--- a/kernel/module/Makefile
+++ b/kernel/module/Makefile@@ -6,3 +6,4 @@ obj-$(CONFIG_MODULES) += main.o obj-$(CONFIG_MODULE_SIG) += signing.o obj-$(CONFIG_MODULE_SIG_FORMAT) += signature.o +obj-$(CONFIG_LIVEPATCH) += livepatch.o
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index ffc50df010a7..91ef152aeffb 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h@@ -51,3 +51,15 @@ struct load_info { }; extern int mod_verify_sig(const void *mod, struct load_info *info); + +#ifdef CONFIG_LIVEPATCH +extern int copy_module_elf(struct module *mod, struct load_info *info); +extern void free_module_elf(struct module *mod); +extern int check_modinfo_livepatch(struct module *mod, struct load_info *info); +#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 */
diff --git a/kernel/module/livepatch.c b/kernel/module/livepatch.c
new file mode 100644
index 000000000000..e147f5418327
--- /dev/null
+++ b/kernel/module/livepatch.c@@ -0,0 +1,75 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * kernel/module/livepatch.c - 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 == 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; +} + +void free_module_elf(struct module *mod) +{ + kfree(mod->klp_info->sechdrs); + kfree(mod->klp_info->secstrings); + kfree(mod->klp_info); +}
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 2a6b859716c0..9bcaf251e109 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c@@ -2043,81 +2043,6 @@ 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) { /*
@@ -3052,19 +2977,7 @@ 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; - add_taint_module(mod, TAINT_LIVEPATCH, LOCKDEP_STILL_OK); - pr_notice_once("%s: tainting kernel with TAINT_LIVEPATCH\n", - mod->name); - } - - return 0; -} -#else /* !CONFIG_LIVEPATCH */ +#ifndef CONFIG_LIVEPATCH static int check_modinfo_livepatch(struct module *mod, struct load_info *info) { if (get_modinfo(info, "livepatch")) {
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