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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 "internal.h"
static void 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];
set_vm_flush_reset_perms(mod_mem->base);
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.
*/
void module_enable_rox(const struct module *mod)
{
for_class_mod_mem_type(type, text) {
if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
module_set_memory(mod, type, set_memory_rox);
else
module_set_memory(mod, type, set_memory_x);
}
}
void module_enable_ro(const struct module *mod, bool after_init)
{
if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
return;
#ifdef CONFIG_STRICT_MODULE_RWX
if (!rodata_enabled)
return;
#endif
module_set_memory(mod, MOD_RODATA, set_memory_ro);
module_set_memory(mod, MOD_INIT_RODATA, set_memory_ro);
if (after_init)
module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro);
}
void module_enable_nx(const struct module *mod)
{
if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
return;
for_class_mod_mem_type(type, data)
module_set_memory(mod, type, set_memory_nx);
}
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;
}
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