1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * VDSO implementations. 4 * 5 * Copyright (C) 2012 ARM Limited 6 * 7 * Author: Will Deacon <will.deacon@arm.com> 8 */ 9 10 #include <linux/cache.h> 11 #include <linux/clocksource.h> 12 #include <linux/elf.h> 13 #include <linux/err.h> 14 #include <linux/errno.h> 15 #include <linux/gfp.h> 16 #include <linux/kernel.h> 17 #include <linux/mm.h> 18 #include <linux/sched.h> 19 #include <linux/signal.h> 20 #include <linux/slab.h> 21 #include <linux/vdso_datastore.h> 22 #include <linux/vmalloc.h> 23 #include <vdso/datapage.h> 24 #include <vdso/helpers.h> 25 26 #include <asm/cacheflush.h> 27 #include <asm/signal32.h> 28 #include <asm/vdso.h> 29 30 enum vdso_abi { 31 VDSO_ABI_AA64, 32 VDSO_ABI_AA32, 33 }; 34 35 struct vdso_abi_info { 36 const char *name; 37 const char *vdso_code_start; 38 const char *vdso_code_end; 39 unsigned long vdso_pages; 40 /* Code Mapping */ 41 struct vm_special_mapping *cm; 42 }; 43 44 static struct vdso_abi_info vdso_info[] __ro_after_init = { 45 [VDSO_ABI_AA64] = { 46 .name = "vdso", 47 .vdso_code_start = vdso_start, 48 .vdso_code_end = vdso_end, 49 }, 50 #ifdef CONFIG_COMPAT_VDSO 51 [VDSO_ABI_AA32] = { 52 .name = "vdso32", 53 .vdso_code_start = vdso32_start, 54 .vdso_code_end = vdso32_end, 55 }, 56 #endif /* CONFIG_COMPAT_VDSO */ 57 }; 58 59 static int vdso_mremap(const struct vm_special_mapping *sm, 60 struct vm_area_struct *new_vma) 61 { 62 current->mm->context.vdso = (void *)new_vma->vm_start; 63 64 return 0; 65 } 66 67 static int __init __vdso_init(enum vdso_abi abi) 68 { 69 int i; 70 struct page **vdso_pagelist; 71 unsigned long pfn; 72 73 if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4)) { 74 pr_err("vDSO is not a valid ELF object!\n"); 75 return -EINVAL; 76 } 77 78 vdso_info[abi].vdso_pages = ( 79 vdso_info[abi].vdso_code_end - 80 vdso_info[abi].vdso_code_start) >> 81 PAGE_SHIFT; 82 83 vdso_pagelist = kzalloc_objs(struct page *, vdso_info[abi].vdso_pages); 84 if (vdso_pagelist == NULL) 85 return -ENOMEM; 86 87 /* Grab the vDSO code pages. */ 88 pfn = sym_to_pfn(vdso_info[abi].vdso_code_start); 89 90 for (i = 0; i < vdso_info[abi].vdso_pages; i++) 91 vdso_pagelist[i] = pfn_to_page(pfn + i); 92 93 vdso_info[abi].cm->pages = vdso_pagelist; 94 95 return 0; 96 } 97 98 static int __setup_additional_pages(enum vdso_abi abi, 99 struct mm_struct *mm, 100 struct linux_binprm *bprm, 101 int uses_interp) 102 { 103 unsigned long vdso_base, vdso_text_len, vdso_mapping_len; 104 unsigned long gp_flags = 0; 105 void *ret; 106 107 BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES); 108 109 vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT; 110 /* Be sure to map the data page */ 111 vdso_mapping_len = vdso_text_len + VDSO_NR_PAGES * PAGE_SIZE; 112 113 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 114 if (IS_ERR_VALUE(vdso_base)) { 115 ret = ERR_PTR(vdso_base); 116 goto up_fail; 117 } 118 119 ret = vdso_install_vvar_mapping(mm, vdso_base); 120 if (IS_ERR(ret)) 121 goto up_fail; 122 123 if (system_supports_bti_kernel()) 124 gp_flags = VM_ARM64_BTI; 125 126 vdso_base += VDSO_NR_PAGES * PAGE_SIZE; 127 mm->context.vdso = (void *)vdso_base; 128 ret = _install_special_mapping(mm, vdso_base, vdso_text_len, 129 VM_READ|VM_EXEC|gp_flags| 130 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC| 131 VM_SEALED_SYSMAP, 132 vdso_info[abi].cm); 133 if (IS_ERR(ret)) 134 goto up_fail; 135 136 return 0; 137 138 up_fail: 139 mm->context.vdso = NULL; 140 return PTR_ERR(ret); 141 } 142 143 #ifdef CONFIG_COMPAT 144 /* 145 * Create and map the vectors page for AArch32 tasks. 146 */ 147 enum aarch32_map { 148 AA32_MAP_VECTORS, /* kuser helpers */ 149 AA32_MAP_SIGPAGE, 150 AA32_MAP_VDSO, 151 }; 152 153 static struct page *aarch32_vectors_page __ro_after_init; 154 static struct page *aarch32_sig_page __ro_after_init; 155 156 static int aarch32_sigpage_mremap(const struct vm_special_mapping *sm, 157 struct vm_area_struct *new_vma) 158 { 159 current->mm->context.sigpage = (void *)new_vma->vm_start; 160 161 return 0; 162 } 163 164 static struct vm_special_mapping aarch32_vdso_maps[] = { 165 [AA32_MAP_VECTORS] = { 166 .name = "[vectors]", /* ABI */ 167 .pages = &aarch32_vectors_page, 168 }, 169 [AA32_MAP_SIGPAGE] = { 170 .name = "[sigpage]", /* ABI */ 171 .pages = &aarch32_sig_page, 172 .mremap = aarch32_sigpage_mremap, 173 }, 174 [AA32_MAP_VDSO] = { 175 .name = "[vdso]", 176 .mremap = vdso_mremap, 177 }, 178 }; 179 180 static int aarch32_alloc_kuser_vdso_page(void) 181 { 182 extern char __kuser_helper_start[], __kuser_helper_end[]; 183 int kuser_sz = __kuser_helper_end - __kuser_helper_start; 184 unsigned long vdso_page; 185 186 if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) 187 return 0; 188 189 vdso_page = get_zeroed_page(GFP_KERNEL); 190 if (!vdso_page) 191 return -ENOMEM; 192 193 memcpy((void *)(vdso_page + 0x1000 - kuser_sz), __kuser_helper_start, 194 kuser_sz); 195 aarch32_vectors_page = virt_to_page((void *)vdso_page); 196 return 0; 197 } 198 199 #define COMPAT_SIGPAGE_POISON_WORD 0xe7fddef1 200 static int aarch32_alloc_sigpage(void) 201 { 202 extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[]; 203 int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start; 204 __le32 poison = cpu_to_le32(COMPAT_SIGPAGE_POISON_WORD); 205 void *sigpage; 206 207 sigpage = (void *)__get_free_page(GFP_KERNEL); 208 if (!sigpage) 209 return -ENOMEM; 210 211 memset32(sigpage, (__force u32)poison, PAGE_SIZE / sizeof(poison)); 212 memcpy(sigpage, __aarch32_sigret_code_start, sigret_sz); 213 aarch32_sig_page = virt_to_page(sigpage); 214 return 0; 215 } 216 217 static int __init __aarch32_alloc_vdso_pages(void) 218 { 219 220 if (!IS_ENABLED(CONFIG_COMPAT_VDSO)) 221 return 0; 222 223 vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO]; 224 225 return __vdso_init(VDSO_ABI_AA32); 226 } 227 228 static int __init aarch32_alloc_vdso_pages(void) 229 { 230 int ret; 231 232 ret = __aarch32_alloc_vdso_pages(); 233 if (ret) 234 return ret; 235 236 ret = aarch32_alloc_sigpage(); 237 if (ret) 238 return ret; 239 240 return aarch32_alloc_kuser_vdso_page(); 241 } 242 arch_initcall(aarch32_alloc_vdso_pages); 243 244 static int aarch32_kuser_helpers_setup(struct mm_struct *mm) 245 { 246 void *ret; 247 248 if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) 249 return 0; 250 251 /* 252 * Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's 253 * not safe to CoW the page containing the CPU exception vectors. 254 */ 255 ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE, 256 VM_READ | VM_EXEC | 257 VM_MAYREAD | VM_MAYEXEC | 258 VM_SEALED_SYSMAP, 259 &aarch32_vdso_maps[AA32_MAP_VECTORS]); 260 261 return PTR_ERR_OR_ZERO(ret); 262 } 263 264 static int aarch32_sigreturn_setup(struct mm_struct *mm) 265 { 266 unsigned long addr; 267 void *ret; 268 269 addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); 270 if (IS_ERR_VALUE(addr)) { 271 ret = ERR_PTR(addr); 272 goto out; 273 } 274 275 /* 276 * VM_MAYWRITE is required to allow gdb to Copy-on-Write and 277 * set breakpoints. 278 */ 279 ret = _install_special_mapping(mm, addr, PAGE_SIZE, 280 VM_READ | VM_EXEC | VM_MAYREAD | 281 VM_MAYWRITE | VM_MAYEXEC | 282 VM_SEALED_SYSMAP, 283 &aarch32_vdso_maps[AA32_MAP_SIGPAGE]); 284 if (IS_ERR(ret)) 285 goto out; 286 287 mm->context.sigpage = (void *)addr; 288 289 out: 290 return PTR_ERR_OR_ZERO(ret); 291 } 292 293 int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 294 { 295 struct mm_struct *mm = current->mm; 296 int ret; 297 298 if (mmap_write_lock_killable(mm)) 299 return -EINTR; 300 301 ret = aarch32_kuser_helpers_setup(mm); 302 if (ret) 303 goto out; 304 305 if (IS_ENABLED(CONFIG_COMPAT_VDSO)) { 306 ret = __setup_additional_pages(VDSO_ABI_AA32, mm, bprm, 307 uses_interp); 308 if (ret) 309 goto out; 310 } 311 312 ret = aarch32_sigreturn_setup(mm); 313 out: 314 mmap_write_unlock(mm); 315 return ret; 316 } 317 #endif /* CONFIG_COMPAT */ 318 319 static struct vm_special_mapping aarch64_vdso_map __ro_after_init = { 320 .name = "[vdso]", 321 .mremap = vdso_mremap, 322 }; 323 324 static int __init vdso_init(void) 325 { 326 vdso_info[VDSO_ABI_AA64].cm = &aarch64_vdso_map; 327 328 return __vdso_init(VDSO_ABI_AA64); 329 } 330 arch_initcall(vdso_init); 331 332 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 333 { 334 struct mm_struct *mm = current->mm; 335 int ret; 336 337 if (mmap_write_lock_killable(mm)) 338 return -EINTR; 339 340 ret = __setup_additional_pages(VDSO_ABI_AA64, mm, bprm, uses_interp); 341 mmap_write_unlock(mm); 342 343 return ret; 344 } 345