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