1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Module strict rwx
4 *
5 * Copyright (C) 2015 Rusty Russell
6 */
7
8 #include <linux/module.h>
9 #include <linux/mm.h>
10 #include <linux/vmalloc.h>
11 #include <linux/set_memory.h>
12 #include "internal.h"
13
module_set_memory(const struct module * mod,enum mod_mem_type type,int (* set_memory)(unsigned long start,int num_pages))14 static int module_set_memory(const struct module *mod, enum mod_mem_type type,
15 int (*set_memory)(unsigned long start, int num_pages))
16 {
17 const struct module_memory *mod_mem = &mod->mem[type];
18
19 if (!mod_mem->base)
20 return 0;
21
22 set_vm_flush_reset_perms(mod_mem->base);
23 return set_memory((unsigned long)mod_mem->base, mod_mem->size >> PAGE_SHIFT);
24 }
25
26 /*
27 * Since some arches are moving towards PAGE_KERNEL module allocations instead
28 * of PAGE_KERNEL_EXEC, keep module_enable_x() independent of
29 * CONFIG_STRICT_MODULE_RWX because they are needed regardless of whether we
30 * are strict.
31 */
module_enable_text_rox(const struct module * mod)32 int module_enable_text_rox(const struct module *mod)
33 {
34 for_class_mod_mem_type(type, text) {
35 int ret;
36
37 if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
38 ret = module_set_memory(mod, type, set_memory_rox);
39 else
40 ret = module_set_memory(mod, type, set_memory_x);
41 if (ret)
42 return ret;
43 }
44 return 0;
45 }
46
module_enable_rodata_ro(const struct module * mod,bool after_init)47 int module_enable_rodata_ro(const struct module *mod, bool after_init)
48 {
49 int ret;
50
51 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX) || !rodata_enabled)
52 return 0;
53
54 ret = module_set_memory(mod, MOD_RODATA, set_memory_ro);
55 if (ret)
56 return ret;
57 ret = module_set_memory(mod, MOD_INIT_RODATA, set_memory_ro);
58 if (ret)
59 return ret;
60
61 if (after_init)
62 return module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro);
63
64 return 0;
65 }
66
module_enable_data_nx(const struct module * mod)67 int module_enable_data_nx(const struct module *mod)
68 {
69 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
70 return 0;
71
72 for_class_mod_mem_type(type, data) {
73 int ret = module_set_memory(mod, type, set_memory_nx);
74
75 if (ret)
76 return ret;
77 }
78 return 0;
79 }
80
module_enforce_rwx_sections(Elf_Ehdr * hdr,Elf_Shdr * sechdrs,char * secstrings,struct module * mod)81 int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
82 char *secstrings, struct module *mod)
83 {
84 const unsigned long shf_wx = SHF_WRITE | SHF_EXECINSTR;
85 int i;
86
87 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
88 return 0;
89
90 for (i = 0; i < hdr->e_shnum; i++) {
91 if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) {
92 pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n",
93 mod->name, secstrings + sechdrs[i].sh_name, i);
94 return -ENOEXEC;
95 }
96 }
97
98 return 0;
99 }
100