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 */
18 int 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
62 free_sechdrs:
63 kfree(mod->klp_info->sechdrs);
64 free_info:
65 kfree(mod->klp_info);
66 return ret;
67 }
68
69 void 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
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