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 <linux/execmem.h> 13 #include "internal.h" 14 15 static int module_set_memory(const struct module *mod, enum mod_mem_type type, 16 int (*set_memory)(unsigned long start, int num_pages)) 17 { 18 const struct module_memory *mod_mem = &mod->mem[type]; 19 20 if (!mod_mem->base) 21 return 0; 22 23 set_vm_flush_reset_perms(mod_mem->base); 24 return set_memory((unsigned long)mod_mem->base, mod_mem->size >> PAGE_SHIFT); 25 } 26 27 /* 28 * Since some arches are moving towards PAGE_KERNEL module allocations instead 29 * of PAGE_KERNEL_EXEC, keep module_enable_x() independent of 30 * CONFIG_STRICT_MODULE_RWX because they are needed regardless of whether we 31 * are strict. 32 */ 33 int module_enable_text_rox(const struct module *mod) 34 { 35 for_class_mod_mem_type(type, text) { 36 const struct module_memory *mem = &mod->mem[type]; 37 int ret; 38 39 if (mem->is_rox) 40 ret = execmem_restore_rox(mem->base, mem->size); 41 else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) 42 ret = module_set_memory(mod, type, set_memory_rox); 43 else 44 ret = module_set_memory(mod, type, set_memory_x); 45 if (ret) 46 return ret; 47 } 48 return 0; 49 } 50 51 int module_enable_rodata_ro(const struct module *mod) 52 { 53 int ret; 54 55 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX) || !rodata_enabled) 56 return 0; 57 58 ret = module_set_memory(mod, MOD_RODATA, set_memory_ro); 59 if (ret) 60 return ret; 61 ret = module_set_memory(mod, MOD_INIT_RODATA, set_memory_ro); 62 if (ret) 63 return ret; 64 65 return 0; 66 } 67 68 int module_enable_rodata_ro_after_init(const struct module *mod) 69 { 70 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX) || !rodata_enabled) 71 return 0; 72 73 return module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro); 74 } 75 76 int module_enable_data_nx(const struct module *mod) 77 { 78 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) 79 return 0; 80 81 for_class_mod_mem_type(type, data) { 82 int ret = module_set_memory(mod, type, set_memory_nx); 83 84 if (ret) 85 return ret; 86 } 87 return 0; 88 } 89 90 int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, 91 char *secstrings, struct module *mod) 92 { 93 const unsigned long shf_wx = SHF_WRITE | SHF_EXECINSTR; 94 int i; 95 96 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) 97 return 0; 98 99 for (i = 0; i < hdr->e_shnum; i++) { 100 if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) { 101 pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n", 102 mod->name, secstrings + sechdrs[i].sh_name, i); 103 return -ENOEXEC; 104 } 105 } 106 107 return 0; 108 } 109