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