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