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 (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) 38 ret = module_set_memory(mod, type, set_memory_rox); 39 else 40 ret = module_set_memory(mod, type, set_memory_x); 41 if (ret) 42 return ret; 43 } 44 return 0; 45 } 46 47 int module_enable_rodata_ro(const struct module *mod, bool after_init) 48 { 49 int ret; 50 51 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX) || !rodata_enabled) 52 return 0; 53 54 ret = module_set_memory(mod, MOD_RODATA, set_memory_ro); 55 if (ret) 56 return ret; 57 ret = module_set_memory(mod, MOD_INIT_RODATA, set_memory_ro); 58 if (ret) 59 return ret; 60 61 if (after_init) 62 return module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro); 63 64 return 0; 65 } 66 67 int module_enable_data_nx(const struct module *mod) 68 { 69 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) 70 return 0; 71 72 for_class_mod_mem_type(type, data) { 73 int ret = module_set_memory(mod, type, set_memory_nx); 74 75 if (ret) 76 return ret; 77 } 78 return 0; 79 } 80 81 int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, 82 char *secstrings, struct module *mod) 83 { 84 const unsigned long shf_wx = SHF_WRITE | SHF_EXECINSTR; 85 int i; 86 87 if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) 88 return 0; 89 90 for (i = 0; i < hdr->e_shnum; i++) { 91 if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) { 92 pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n", 93 mod->name, secstrings + sechdrs[i].sh_name, i); 94 return -ENOEXEC; 95 } 96 } 97 98 return 0; 99 } 100