1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Module livepatch support
4 *
5 * Copyright (C) 2016 Jessica Yu <jeyu@redhat.com>
6 */
7
8#include <linux/module.h>
9#include <linux/string.h>
10#include <linux/slab.h>
11#include "internal.h"
12
13/*
14 * Persist ELF information about a module. Copy the ELF header,
15 * section header table, section string table, and symtab section
16 * index from info to mod->klp_info.
17 */
18int copy_module_elf(struct module *mod, struct load_info *info)
19{
20	unsigned int size, symndx;
21	int ret;
22
23	size = sizeof(*mod->klp_info);
24	mod->klp_info = kmalloc(size, GFP_KERNEL);
25	if (!mod->klp_info)
26		return -ENOMEM;
27
28	/* ELF header */
29	size = sizeof(mod->klp_info->hdr);
30	memcpy(&mod->klp_info->hdr, info->hdr, size);
31
32	/* ELF section header table */
33	size = sizeof(*info->sechdrs) * info->hdr->e_shnum;
34	mod->klp_info->sechdrs = kmemdup(info->sechdrs, size, GFP_KERNEL);
35	if (!mod->klp_info->sechdrs) {
36		ret = -ENOMEM;
37		goto free_info;
38	}
39
40	/* ELF section name string table */
41	size = info->sechdrs[info->hdr->e_shstrndx].sh_size;
42	mod->klp_info->secstrings = kmemdup(info->secstrings, size, GFP_KERNEL);
43	if (!mod->klp_info->secstrings) {
44		ret = -ENOMEM;
45		goto free_sechdrs;
46	}
47
48	/* ELF symbol section index */
49	symndx = info->index.sym;
50	mod->klp_info->symndx = symndx;
51
52	/*
53	 * For livepatch modules, core_kallsyms.symtab is a complete
54	 * copy of the original symbol table. Adjust sh_addr to point
55	 * to core_kallsyms.symtab since the copy of the symtab in module
56	 * init memory is freed at the end of do_init_module().
57	 */
58	mod->klp_info->sechdrs[symndx].sh_addr = (unsigned long)mod->core_kallsyms.symtab;
59
60	return 0;
61
62free_sechdrs:
63	kfree(mod->klp_info->sechdrs);
64free_info:
65	kfree(mod->klp_info);
66	return ret;
67}
68
69void free_module_elf(struct module *mod)
70{
71	kfree(mod->klp_info->sechdrs);
72	kfree(mod->klp_info->secstrings);
73	kfree(mod->klp_info);
74}
75