1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp. 4 * <benh@kernel.crashing.org> 5 * Copyright (C) 2012 ARM Limited 6 * Copyright (C) 2015 Regents of the University of California 7 */ 8 9 #include <linux/elf.h> 10 #include <linux/mm.h> 11 #include <linux/slab.h> 12 #include <linux/binfmts.h> 13 #include <linux/err.h> 14 #include <asm/page.h> 15 #include <asm/vdso.h> 16 #include <linux/time_namespace.h> 17 #include <vdso/datapage.h> 18 #include <vdso/vsyscall.h> 19 20 enum vvar_pages { 21 VVAR_DATA_PAGE_OFFSET, 22 VVAR_TIMENS_PAGE_OFFSET, 23 VVAR_NR_PAGES, 24 }; 25 26 enum rv_vdso_map { 27 RV_VDSO_MAP_VVAR, 28 RV_VDSO_MAP_VDSO, 29 }; 30 31 #define VVAR_SIZE (VVAR_NR_PAGES << PAGE_SHIFT) 32 33 /* 34 * The vDSO data page. 35 */ 36 static union { 37 struct vdso_data data; 38 u8 page[PAGE_SIZE]; 39 } vdso_data_store __page_aligned_data; 40 struct vdso_data *vdso_data = &vdso_data_store.data; 41 42 struct __vdso_info { 43 const char *name; 44 const char *vdso_code_start; 45 const char *vdso_code_end; 46 unsigned long vdso_pages; 47 /* Data Mapping */ 48 struct vm_special_mapping *dm; 49 /* Code Mapping */ 50 struct vm_special_mapping *cm; 51 }; 52 53 static struct __vdso_info vdso_info; 54 #ifdef CONFIG_COMPAT 55 static struct __vdso_info compat_vdso_info; 56 #endif 57 58 static int vdso_mremap(const struct vm_special_mapping *sm, 59 struct vm_area_struct *new_vma) 60 { 61 current->mm->context.vdso = (void *)new_vma->vm_start; 62 63 return 0; 64 } 65 66 static void __init __vdso_init(struct __vdso_info *vdso_info) 67 { 68 unsigned int i; 69 struct page **vdso_pagelist; 70 unsigned long pfn; 71 72 if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4)) 73 panic("vDSO is not a valid ELF object!\n"); 74 75 vdso_info->vdso_pages = ( 76 vdso_info->vdso_code_end - 77 vdso_info->vdso_code_start) >> 78 PAGE_SHIFT; 79 80 vdso_pagelist = kcalloc(vdso_info->vdso_pages, 81 sizeof(struct page *), 82 GFP_KERNEL); 83 if (vdso_pagelist == NULL) 84 panic("vDSO kcalloc failed!\n"); 85 86 /* Grab the vDSO code pages. */ 87 pfn = sym_to_pfn(vdso_info->vdso_code_start); 88 89 for (i = 0; i < vdso_info->vdso_pages; i++) 90 vdso_pagelist[i] = pfn_to_page(pfn + i); 91 92 vdso_info->cm->pages = vdso_pagelist; 93 } 94 95 #ifdef CONFIG_TIME_NS 96 struct vdso_data *arch_get_vdso_data(void *vvar_page) 97 { 98 return (struct vdso_data *)(vvar_page); 99 } 100 101 /* 102 * The vvar mapping contains data for a specific time namespace, so when a task 103 * changes namespace we must unmap its vvar data for the old namespace. 104 * Subsequent faults will map in data for the new namespace. 105 * 106 * For more details see timens_setup_vdso_data(). 107 */ 108 int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) 109 { 110 struct mm_struct *mm = task->mm; 111 struct vm_area_struct *vma; 112 VMA_ITERATOR(vmi, mm, 0); 113 114 mmap_read_lock(mm); 115 116 for_each_vma(vmi, vma) { 117 if (vma_is_special_mapping(vma, vdso_info.dm)) 118 zap_vma_pages(vma); 119 #ifdef CONFIG_COMPAT 120 if (vma_is_special_mapping(vma, compat_vdso_info.dm)) 121 zap_vma_pages(vma); 122 #endif 123 } 124 125 mmap_read_unlock(mm); 126 return 0; 127 } 128 #endif 129 130 static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, 131 struct vm_area_struct *vma, struct vm_fault *vmf) 132 { 133 struct page *timens_page = find_timens_vvar_page(vma); 134 unsigned long pfn; 135 136 switch (vmf->pgoff) { 137 case VVAR_DATA_PAGE_OFFSET: 138 if (timens_page) 139 pfn = page_to_pfn(timens_page); 140 else 141 pfn = sym_to_pfn(vdso_data); 142 break; 143 #ifdef CONFIG_TIME_NS 144 case VVAR_TIMENS_PAGE_OFFSET: 145 /* 146 * If a task belongs to a time namespace then a namespace 147 * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and 148 * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET 149 * offset. 150 * See also the comment near timens_setup_vdso_data(). 151 */ 152 if (!timens_page) 153 return VM_FAULT_SIGBUS; 154 pfn = sym_to_pfn(vdso_data); 155 break; 156 #endif /* CONFIG_TIME_NS */ 157 default: 158 return VM_FAULT_SIGBUS; 159 } 160 161 return vmf_insert_pfn(vma, vmf->address, pfn); 162 } 163 164 static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = { 165 [RV_VDSO_MAP_VVAR] = { 166 .name = "[vvar]", 167 .fault = vvar_fault, 168 }, 169 [RV_VDSO_MAP_VDSO] = { 170 .name = "[vdso]", 171 .mremap = vdso_mremap, 172 }, 173 }; 174 175 static struct __vdso_info vdso_info __ro_after_init = { 176 .name = "vdso", 177 .vdso_code_start = vdso_start, 178 .vdso_code_end = vdso_end, 179 .dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR], 180 .cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO], 181 }; 182 183 #ifdef CONFIG_COMPAT 184 static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = { 185 [RV_VDSO_MAP_VVAR] = { 186 .name = "[vvar]", 187 .fault = vvar_fault, 188 }, 189 [RV_VDSO_MAP_VDSO] = { 190 .name = "[vdso]", 191 .mremap = vdso_mremap, 192 }, 193 }; 194 195 static struct __vdso_info compat_vdso_info __ro_after_init = { 196 .name = "compat_vdso", 197 .vdso_code_start = compat_vdso_start, 198 .vdso_code_end = compat_vdso_end, 199 .dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR], 200 .cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO], 201 }; 202 #endif 203 204 static int __init vdso_init(void) 205 { 206 __vdso_init(&vdso_info); 207 #ifdef CONFIG_COMPAT 208 __vdso_init(&compat_vdso_info); 209 #endif 210 211 return 0; 212 } 213 arch_initcall(vdso_init); 214 215 static int __setup_additional_pages(struct mm_struct *mm, 216 struct linux_binprm *bprm, 217 int uses_interp, 218 struct __vdso_info *vdso_info) 219 { 220 unsigned long vdso_base, vdso_text_len, vdso_mapping_len; 221 void *ret; 222 223 BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES); 224 225 vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT; 226 /* Be sure to map the data page */ 227 vdso_mapping_len = vdso_text_len + VVAR_SIZE; 228 229 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 230 if (IS_ERR_VALUE(vdso_base)) { 231 ret = ERR_PTR(vdso_base); 232 goto up_fail; 233 } 234 235 ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE, 236 (VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info->dm); 237 if (IS_ERR(ret)) 238 goto up_fail; 239 240 vdso_base += VVAR_SIZE; 241 mm->context.vdso = (void *)vdso_base; 242 243 ret = 244 _install_special_mapping(mm, vdso_base, vdso_text_len, 245 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC), 246 vdso_info->cm); 247 248 if (IS_ERR(ret)) 249 goto up_fail; 250 251 return 0; 252 253 up_fail: 254 mm->context.vdso = NULL; 255 return PTR_ERR(ret); 256 } 257 258 #ifdef CONFIG_COMPAT 259 int compat_arch_setup_additional_pages(struct linux_binprm *bprm, 260 int uses_interp) 261 { 262 struct mm_struct *mm = current->mm; 263 int ret; 264 265 if (mmap_write_lock_killable(mm)) 266 return -EINTR; 267 268 ret = __setup_additional_pages(mm, bprm, uses_interp, 269 &compat_vdso_info); 270 mmap_write_unlock(mm); 271 272 return ret; 273 } 274 #endif 275 276 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 277 { 278 struct mm_struct *mm = current->mm; 279 int ret; 280 281 if (mmap_write_lock_killable(mm)) 282 return -EINTR; 283 284 ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info); 285 mmap_write_unlock(mm); 286 287 return ret; 288 } 289