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 #include <vdso/vsyscall.h> 26 27 #include <asm/cacheflush.h> 28 #include <asm/signal32.h> 29 #include <asm/vdso.h> 30 31 enum vdso_abi { 32 VDSO_ABI_AA64, 33 VDSO_ABI_AA32, 34 }; 35 36 struct vdso_abi_info { 37 const char *name; 38 const char *vdso_code_start; 39 const char *vdso_code_end; 40 unsigned long vdso_pages; 41 /* Code Mapping */ 42 struct vm_special_mapping *cm; 43 }; 44 45 static struct vdso_abi_info vdso_info[] __ro_after_init = { 46 [VDSO_ABI_AA64] = { 47 .name = "vdso", 48 .vdso_code_start = vdso_start, 49 .vdso_code_end = vdso_end, 50 }, 51 #ifdef CONFIG_COMPAT_VDSO 52 [VDSO_ABI_AA32] = { 53 .name = "vdso32", 54 .vdso_code_start = vdso32_start, 55 .vdso_code_end = vdso32_end, 56 }, 57 #endif /* CONFIG_COMPAT_VDSO */ 58 }; 59 60 static int vdso_mremap(const struct vm_special_mapping *sm, 61 struct vm_area_struct *new_vma) 62 { 63 current->mm->context.vdso = (void *)new_vma->vm_start; 64 65 return 0; 66 } 67 68 static int __init __vdso_init(enum vdso_abi abi) 69 { 70 int i; 71 struct page **vdso_pagelist; 72 unsigned long pfn; 73 74 if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4)) { 75 pr_err("vDSO is not a valid ELF object!\n"); 76 return -EINVAL; 77 } 78 79 vdso_info[abi].vdso_pages = ( 80 vdso_info[abi].vdso_code_end - 81 vdso_info[abi].vdso_code_start) >> 82 PAGE_SHIFT; 83 84 vdso_pagelist = kzalloc_objs(struct page *, vdso_info[abi].vdso_pages, 85 GFP_KERNEL); 86 if (vdso_pagelist == NULL) 87 return -ENOMEM; 88 89 /* Grab the vDSO code pages. */ 90 pfn = sym_to_pfn(vdso_info[abi].vdso_code_start); 91 92 for (i = 0; i < vdso_info[abi].vdso_pages; i++) 93 vdso_pagelist[i] = pfn_to_page(pfn + i); 94 95 vdso_info[abi].cm->pages = vdso_pagelist; 96 97 return 0; 98 } 99 100 static int __setup_additional_pages(enum vdso_abi abi, 101 struct mm_struct *mm, 102 struct linux_binprm *bprm, 103 int uses_interp) 104 { 105 unsigned long vdso_base, vdso_text_len, vdso_mapping_len; 106 unsigned long gp_flags = 0; 107 void *ret; 108 109 BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES); 110 111 vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT; 112 /* Be sure to map the data page */ 113 vdso_mapping_len = vdso_text_len + VDSO_NR_PAGES * PAGE_SIZE; 114 115 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 116 if (IS_ERR_VALUE(vdso_base)) { 117 ret = ERR_PTR(vdso_base); 118 goto up_fail; 119 } 120 121 ret = vdso_install_vvar_mapping(mm, vdso_base); 122 if (IS_ERR(ret)) 123 goto up_fail; 124 125 if (system_supports_bti_kernel()) 126 gp_flags = VM_ARM64_BTI; 127 128 vdso_base += VDSO_NR_PAGES * PAGE_SIZE; 129 mm->context.vdso = (void *)vdso_base; 130 ret = _install_special_mapping(mm, vdso_base, vdso_text_len, 131 VM_READ|VM_EXEC|gp_flags| 132 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC| 133 VM_SEALED_SYSMAP, 134 vdso_info[abi].cm); 135 if (IS_ERR(ret)) 136 goto up_fail; 137 138 return 0; 139 140 up_fail: 141 mm->context.vdso = NULL; 142 return PTR_ERR(ret); 143 } 144 145 #ifdef CONFIG_COMPAT 146 /* 147 * Create and map the vectors page for AArch32 tasks. 148 */ 149 enum aarch32_map { 150 AA32_MAP_VECTORS, /* kuser helpers */ 151 AA32_MAP_SIGPAGE, 152 AA32_MAP_VDSO, 153 }; 154 155 static struct page *aarch32_vectors_page __ro_after_init; 156 static struct page *aarch32_sig_page __ro_after_init; 157 158 static int aarch32_sigpage_mremap(const struct vm_special_mapping *sm, 159 struct vm_area_struct *new_vma) 160 { 161 current->mm->context.sigpage = (void *)new_vma->vm_start; 162 163 return 0; 164 } 165 166 static struct vm_special_mapping aarch32_vdso_maps[] = { 167 [AA32_MAP_VECTORS] = { 168 .name = "[vectors]", /* ABI */ 169 .pages = &aarch32_vectors_page, 170 }, 171 [AA32_MAP_SIGPAGE] = { 172 .name = "[sigpage]", /* ABI */ 173 .pages = &aarch32_sig_page, 174 .mremap = aarch32_sigpage_mremap, 175 }, 176 [AA32_MAP_VDSO] = { 177 .name = "[vdso]", 178 .mremap = vdso_mremap, 179 }, 180 }; 181 182 static int aarch32_alloc_kuser_vdso_page(void) 183 { 184 extern char __kuser_helper_start[], __kuser_helper_end[]; 185 int kuser_sz = __kuser_helper_end - __kuser_helper_start; 186 unsigned long vdso_page; 187 188 if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) 189 return 0; 190 191 vdso_page = get_zeroed_page(GFP_KERNEL); 192 if (!vdso_page) 193 return -ENOMEM; 194 195 memcpy((void *)(vdso_page + 0x1000 - kuser_sz), __kuser_helper_start, 196 kuser_sz); 197 aarch32_vectors_page = virt_to_page((void *)vdso_page); 198 return 0; 199 } 200 201 #define COMPAT_SIGPAGE_POISON_WORD 0xe7fddef1 202 static int aarch32_alloc_sigpage(void) 203 { 204 extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[]; 205 int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start; 206 __le32 poison = cpu_to_le32(COMPAT_SIGPAGE_POISON_WORD); 207 void *sigpage; 208 209 sigpage = (void *)__get_free_page(GFP_KERNEL); 210 if (!sigpage) 211 return -ENOMEM; 212 213 memset32(sigpage, (__force u32)poison, PAGE_SIZE / sizeof(poison)); 214 memcpy(sigpage, __aarch32_sigret_code_start, sigret_sz); 215 aarch32_sig_page = virt_to_page(sigpage); 216 return 0; 217 } 218 219 static int __init __aarch32_alloc_vdso_pages(void) 220 { 221 222 if (!IS_ENABLED(CONFIG_COMPAT_VDSO)) 223 return 0; 224 225 vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO]; 226 227 return __vdso_init(VDSO_ABI_AA32); 228 } 229 230 static int __init aarch32_alloc_vdso_pages(void) 231 { 232 int ret; 233 234 ret = __aarch32_alloc_vdso_pages(); 235 if (ret) 236 return ret; 237 238 ret = aarch32_alloc_sigpage(); 239 if (ret) 240 return ret; 241 242 return aarch32_alloc_kuser_vdso_page(); 243 } 244 arch_initcall(aarch32_alloc_vdso_pages); 245 246 static int aarch32_kuser_helpers_setup(struct mm_struct *mm) 247 { 248 void *ret; 249 250 if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) 251 return 0; 252 253 /* 254 * Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's 255 * not safe to CoW the page containing the CPU exception vectors. 256 */ 257 ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE, 258 VM_READ | VM_EXEC | 259 VM_MAYREAD | VM_MAYEXEC | 260 VM_SEALED_SYSMAP, 261 &aarch32_vdso_maps[AA32_MAP_VECTORS]); 262 263 return PTR_ERR_OR_ZERO(ret); 264 } 265 266 static int aarch32_sigreturn_setup(struct mm_struct *mm) 267 { 268 unsigned long addr; 269 void *ret; 270 271 addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); 272 if (IS_ERR_VALUE(addr)) { 273 ret = ERR_PTR(addr); 274 goto out; 275 } 276 277 /* 278 * VM_MAYWRITE is required to allow gdb to Copy-on-Write and 279 * set breakpoints. 280 */ 281 ret = _install_special_mapping(mm, addr, PAGE_SIZE, 282 VM_READ | VM_EXEC | VM_MAYREAD | 283 VM_MAYWRITE | VM_MAYEXEC | 284 VM_SEALED_SYSMAP, 285 &aarch32_vdso_maps[AA32_MAP_SIGPAGE]); 286 if (IS_ERR(ret)) 287 goto out; 288 289 mm->context.sigpage = (void *)addr; 290 291 out: 292 return PTR_ERR_OR_ZERO(ret); 293 } 294 295 int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 296 { 297 struct mm_struct *mm = current->mm; 298 int ret; 299 300 if (mmap_write_lock_killable(mm)) 301 return -EINTR; 302 303 ret = aarch32_kuser_helpers_setup(mm); 304 if (ret) 305 goto out; 306 307 if (IS_ENABLED(CONFIG_COMPAT_VDSO)) { 308 ret = __setup_additional_pages(VDSO_ABI_AA32, mm, bprm, 309 uses_interp); 310 if (ret) 311 goto out; 312 } 313 314 ret = aarch32_sigreturn_setup(mm); 315 out: 316 mmap_write_unlock(mm); 317 return ret; 318 } 319 #endif /* CONFIG_COMPAT */ 320 321 static struct vm_special_mapping aarch64_vdso_map __ro_after_init = { 322 .name = "[vdso]", 323 .mremap = vdso_mremap, 324 }; 325 326 static int __init vdso_init(void) 327 { 328 vdso_info[VDSO_ABI_AA64].cm = &aarch64_vdso_map; 329 330 return __vdso_init(VDSO_ABI_AA64); 331 } 332 arch_initcall(vdso_init); 333 334 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 335 { 336 struct mm_struct *mm = current->mm; 337 int ret; 338 339 if (mmap_write_lock_killable(mm)) 340 return -EINTR; 341 342 ret = __setup_additional_pages(VDSO_ABI_AA64, mm, bprm, uses_interp); 343 mmap_write_unlock(mm); 344 345 return ret; 346 } 347