1 /* Kernel module help for x86. 2 Copyright (C) 2001 Rusty Russell. 3 4 This program is free software; you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 2 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program; if not, write to the Free Software 16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 17 */ 18 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 20 21 #include <linux/moduleloader.h> 22 #include <linux/elf.h> 23 #include <linux/vmalloc.h> 24 #include <linux/fs.h> 25 #include <linux/string.h> 26 #include <linux/kernel.h> 27 #include <linux/kasan.h> 28 #include <linux/bug.h> 29 #include <linux/mm.h> 30 #include <linux/gfp.h> 31 #include <linux/jump_label.h> 32 #include <linux/random.h> 33 34 #include <asm/page.h> 35 #include <asm/pgtable.h> 36 #include <asm/setup.h> 37 38 #if 0 39 #define DEBUGP(fmt, ...) \ 40 printk(KERN_DEBUG fmt, ##__VA_ARGS__) 41 #else 42 #define DEBUGP(fmt, ...) \ 43 do { \ 44 if (0) \ 45 printk(KERN_DEBUG fmt, ##__VA_ARGS__); \ 46 } while (0) 47 #endif 48 49 #ifdef CONFIG_RANDOMIZE_BASE 50 static unsigned long module_load_offset; 51 52 /* Mutex protects the module_load_offset. */ 53 static DEFINE_MUTEX(module_kaslr_mutex); 54 55 static unsigned long int get_module_load_offset(void) 56 { 57 if (kaslr_enabled()) { 58 mutex_lock(&module_kaslr_mutex); 59 /* 60 * Calculate the module_load_offset the first time this 61 * code is called. Once calculated it stays the same until 62 * reboot. 63 */ 64 if (module_load_offset == 0) 65 module_load_offset = 66 (get_random_int() % 1024 + 1) * PAGE_SIZE; 67 mutex_unlock(&module_kaslr_mutex); 68 } 69 return module_load_offset; 70 } 71 #else 72 static unsigned long int get_module_load_offset(void) 73 { 74 return 0; 75 } 76 #endif 77 78 void *module_alloc(unsigned long size) 79 { 80 void *p; 81 82 if (PAGE_ALIGN(size) > MODULES_LEN) 83 return NULL; 84 85 p = __vmalloc_node_range(size, MODULE_ALIGN, 86 MODULES_VADDR + get_module_load_offset(), 87 MODULES_END, GFP_KERNEL | __GFP_HIGHMEM, 88 PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, 89 __builtin_return_address(0)); 90 if (p && (kasan_module_alloc(p, size) < 0)) { 91 vfree(p); 92 return NULL; 93 } 94 95 return p; 96 } 97 98 #ifdef CONFIG_X86_32 99 int apply_relocate(Elf32_Shdr *sechdrs, 100 const char *strtab, 101 unsigned int symindex, 102 unsigned int relsec, 103 struct module *me) 104 { 105 unsigned int i; 106 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr; 107 Elf32_Sym *sym; 108 uint32_t *location; 109 110 DEBUGP("Applying relocate section %u to %u\n", 111 relsec, sechdrs[relsec].sh_info); 112 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 113 /* This is where to make the change */ 114 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 115 + rel[i].r_offset; 116 /* This is the symbol it is referring to. Note that all 117 undefined symbols have been resolved. */ 118 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 119 + ELF32_R_SYM(rel[i].r_info); 120 121 switch (ELF32_R_TYPE(rel[i].r_info)) { 122 case R_386_32: 123 /* We add the value into the location given */ 124 *location += sym->st_value; 125 break; 126 case R_386_PC32: 127 /* Add the value, subtract its position */ 128 *location += sym->st_value - (uint32_t)location; 129 break; 130 default: 131 pr_err("%s: Unknown relocation: %u\n", 132 me->name, ELF32_R_TYPE(rel[i].r_info)); 133 return -ENOEXEC; 134 } 135 } 136 return 0; 137 } 138 #else /*X86_64*/ 139 int apply_relocate_add(Elf64_Shdr *sechdrs, 140 const char *strtab, 141 unsigned int symindex, 142 unsigned int relsec, 143 struct module *me) 144 { 145 unsigned int i; 146 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; 147 Elf64_Sym *sym; 148 void *loc; 149 u64 val; 150 151 DEBUGP("Applying relocate section %u to %u\n", 152 relsec, sechdrs[relsec].sh_info); 153 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 154 /* This is where to make the change */ 155 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 156 + rel[i].r_offset; 157 158 /* This is the symbol it is referring to. Note that all 159 undefined symbols have been resolved. */ 160 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr 161 + ELF64_R_SYM(rel[i].r_info); 162 163 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n", 164 (int)ELF64_R_TYPE(rel[i].r_info), 165 sym->st_value, rel[i].r_addend, (u64)loc); 166 167 val = sym->st_value + rel[i].r_addend; 168 169 switch (ELF64_R_TYPE(rel[i].r_info)) { 170 case R_X86_64_NONE: 171 break; 172 case R_X86_64_64: 173 *(u64 *)loc = val; 174 break; 175 case R_X86_64_32: 176 *(u32 *)loc = val; 177 if (val != *(u32 *)loc) 178 goto overflow; 179 break; 180 case R_X86_64_32S: 181 *(s32 *)loc = val; 182 if ((s64)val != *(s32 *)loc) 183 goto overflow; 184 break; 185 case R_X86_64_PC32: 186 val -= (u64)loc; 187 *(u32 *)loc = val; 188 #if 0 189 if ((s64)val != *(s32 *)loc) 190 goto overflow; 191 #endif 192 break; 193 default: 194 pr_err("%s: Unknown rela relocation: %llu\n", 195 me->name, ELF64_R_TYPE(rel[i].r_info)); 196 return -ENOEXEC; 197 } 198 } 199 return 0; 200 201 overflow: 202 pr_err("overflow in relocation type %d val %Lx\n", 203 (int)ELF64_R_TYPE(rel[i].r_info), val); 204 pr_err("`%s' likely not compiled with -mcmodel=kernel\n", 205 me->name); 206 return -ENOEXEC; 207 } 208 #endif 209 210 int module_finalize(const Elf_Ehdr *hdr, 211 const Elf_Shdr *sechdrs, 212 struct module *me) 213 { 214 const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL, 215 *para = NULL; 216 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 217 218 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { 219 if (!strcmp(".text", secstrings + s->sh_name)) 220 text = s; 221 if (!strcmp(".altinstructions", secstrings + s->sh_name)) 222 alt = s; 223 if (!strcmp(".smp_locks", secstrings + s->sh_name)) 224 locks = s; 225 if (!strcmp(".parainstructions", secstrings + s->sh_name)) 226 para = s; 227 } 228 229 if (alt) { 230 /* patch .altinstructions */ 231 void *aseg = (void *)alt->sh_addr; 232 apply_alternatives(aseg, aseg + alt->sh_size); 233 } 234 if (locks && text) { 235 void *lseg = (void *)locks->sh_addr; 236 void *tseg = (void *)text->sh_addr; 237 alternatives_smp_module_add(me, me->name, 238 lseg, lseg + locks->sh_size, 239 tseg, tseg + text->sh_size); 240 } 241 242 if (para) { 243 void *pseg = (void *)para->sh_addr; 244 apply_paravirt(pseg, pseg + para->sh_size); 245 } 246 247 /* make jump label nops */ 248 jump_label_apply_nops(me); 249 250 return 0; 251 } 252 253 void module_arch_cleanup(struct module *mod) 254 { 255 alternatives_smp_module_del(mod); 256 } 257