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// 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 <linux/execmem.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) {
const struct module_memory *mem = &mod->mem[type];
int ret;
if (mem->is_rox)
ret = execmem_restore_rox(mem->base, mem->size);
else 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)
{
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;
return 0;
}
int module_enable_rodata_ro_after_init(const struct module *mod)
{
if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX) || !rodata_enabled)
return 0;
return module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro);
}
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(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
const char *secstrings,
const 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;
}
static const char *const ro_after_init[] = {
/*
* Section .data..ro_after_init holds data explicitly annotated by
* __ro_after_init.
*/
".data..ro_after_init",
/*
* Section __jump_table holds data structures that are never modified,
* with the exception of entries that refer to code in the __init
* section, which are marked as such at module load time.
*/
"__jump_table",
#ifdef CONFIG_HAVE_STATIC_CALL_INLINE
/*
* Section .static_call_sites holds data structures that need to be
* sorted and processed at module load time but are never modified
* afterwards.
*/
".static_call_sites",
#endif
};
void module_mark_ro_after_init(const Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
const char *secstrings)
{
int i, j;
for (i = 1; i < hdr->e_shnum; i++) {
Elf_Shdr *shdr = &sechdrs[i];
for (j = 0; j < ARRAY_SIZE(ro_after_init); j++) {
if (strcmp(secstrings + shdr->sh_name,
ro_after_init[j]) == 0) {
shdr->sh_flags |= SHF_RO_AFTER_INIT;
break;
}
}
}
}
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