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 void 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 set_vm_flush_reset_perms(mod_mem->base);
20 set_memory((unsigned long)mod_mem->base, mod_mem->size >> PAGE_SHIFT);
21 }
22
23 /*
24 * Since some arches are moving towards PAGE_KERNEL module allocations instead
25 * of PAGE_KERNEL_EXEC, keep module_enable_x() independent of
26 * CONFIG_STRICT_MODULE_RWX because they are needed regardless of whether we
27 * are strict.
28 */
module_enable_x(const struct module * mod)29 void module_enable_x(const struct module *mod)
30 {
31 for_class_mod_mem_type(type, text)
32 module_set_memory(mod, type, set_memory_x);
33 }
34
module_enable_ro(const struct module * mod,bool after_init)35 void module_enable_ro(const struct module *mod, bool after_init)
36 {
37 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
38 return;
39 #ifdef CONFIG_STRICT_MODULE_RWX
40 if (!rodata_enabled)
41 return;
42 #endif
43
44 module_set_memory(mod, MOD_TEXT, set_memory_ro);
45 module_set_memory(mod, MOD_INIT_TEXT, set_memory_ro);
46 module_set_memory(mod, MOD_RODATA, set_memory_ro);
47 module_set_memory(mod, MOD_INIT_RODATA, set_memory_ro);
48
49 if (after_init)
50 module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro);
51 }
52
module_enable_nx(const struct module * mod)53 void module_enable_nx(const struct module *mod)
54 {
55 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
56 return;
57
58 for_class_mod_mem_type(type, data)
59 module_set_memory(mod, type, set_memory_nx);
60 }
61
module_enforce_rwx_sections(Elf_Ehdr * hdr,Elf_Shdr * sechdrs,char * secstrings,struct module * mod)62 int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
63 char *secstrings, struct module *mod)
64 {
65 const unsigned long shf_wx = SHF_WRITE | SHF_EXECINSTR;
66 int i;
67
68 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
69 return 0;
70
71 for (i = 0; i < hdr->e_shnum; i++) {
72 if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) {
73 pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n",
74 mod->name, secstrings + sechdrs[i].sh_name, i);
75 return -ENOEXEC;
76 }
77 }
78
79 return 0;
80 }
81
