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/vdso_datastore.h> 17 #include <vdso/datapage.h> 18 #include <vdso/vsyscall.h> 19 20 #define VVAR_SIZE (VDSO_NR_PAGES << PAGE_SHIFT) 21 22 struct __vdso_info { 23 const char *name; 24 const char *vdso_code_start; 25 const char *vdso_code_end; 26 unsigned long vdso_pages; 27 /* Code Mapping */ 28 struct vm_special_mapping *cm; 29 }; 30 31 static struct __vdso_info vdso_info; 32 #ifdef CONFIG_COMPAT 33 static struct __vdso_info compat_vdso_info; 34 #endif 35 36 static int vdso_mremap(const struct vm_special_mapping *sm, 37 struct vm_area_struct *new_vma) 38 { 39 current->mm->context.vdso = (void *)new_vma->vm_start; 40 41 return 0; 42 } 43 44 static void __init __vdso_init(struct __vdso_info *vdso_info) 45 { 46 unsigned int i; 47 struct page **vdso_pagelist; 48 unsigned long pfn; 49 50 if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4)) 51 panic("vDSO is not a valid ELF object!\n"); 52 53 vdso_info->vdso_pages = ( 54 vdso_info->vdso_code_end - 55 vdso_info->vdso_code_start) >> 56 PAGE_SHIFT; 57 58 vdso_pagelist = kcalloc(vdso_info->vdso_pages, 59 sizeof(struct page *), 60 GFP_KERNEL); 61 if (vdso_pagelist == NULL) 62 panic("vDSO kcalloc failed!\n"); 63 64 /* Grab the vDSO code pages. */ 65 pfn = sym_to_pfn(vdso_info->vdso_code_start); 66 67 for (i = 0; i < vdso_info->vdso_pages; i++) 68 vdso_pagelist[i] = pfn_to_page(pfn + i); 69 70 vdso_info->cm->pages = vdso_pagelist; 71 } 72 73 static struct vm_special_mapping rv_vdso_map __ro_after_init = { 74 .name = "[vdso]", 75 .mremap = vdso_mremap, 76 }; 77 78 static struct __vdso_info vdso_info __ro_after_init = { 79 .name = "vdso", 80 .vdso_code_start = vdso_start, 81 .vdso_code_end = vdso_end, 82 .cm = &rv_vdso_map, 83 }; 84 85 #ifdef CONFIG_COMPAT 86 static struct vm_special_mapping rv_compat_vdso_map __ro_after_init = { 87 .name = "[vdso]", 88 .mremap = vdso_mremap, 89 }; 90 91 static struct __vdso_info compat_vdso_info __ro_after_init = { 92 .name = "compat_vdso", 93 .vdso_code_start = compat_vdso_start, 94 .vdso_code_end = compat_vdso_end, 95 .cm = &rv_compat_vdso_map, 96 }; 97 #endif 98 99 static int __init vdso_init(void) 100 { 101 __vdso_init(&vdso_info); 102 #ifdef CONFIG_COMPAT 103 __vdso_init(&compat_vdso_info); 104 #endif 105 106 return 0; 107 } 108 arch_initcall(vdso_init); 109 110 static int __setup_additional_pages(struct mm_struct *mm, 111 struct linux_binprm *bprm, 112 int uses_interp, 113 struct __vdso_info *vdso_info) 114 { 115 unsigned long vdso_base, vdso_text_len, vdso_mapping_len; 116 void *ret; 117 118 BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES); 119 120 vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT; 121 /* Be sure to map the data page */ 122 vdso_mapping_len = vdso_text_len + VVAR_SIZE; 123 124 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 125 if (IS_ERR_VALUE(vdso_base)) { 126 ret = ERR_PTR(vdso_base); 127 goto up_fail; 128 } 129 130 ret = vdso_install_vvar_mapping(mm, vdso_base); 131 if (IS_ERR(ret)) 132 goto up_fail; 133 134 vdso_base += VVAR_SIZE; 135 mm->context.vdso = (void *)vdso_base; 136 137 ret = 138 _install_special_mapping(mm, vdso_base, vdso_text_len, 139 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC | VM_SEALED_SYSMAP), 140 vdso_info->cm); 141 142 if (IS_ERR(ret)) 143 goto up_fail; 144 145 return 0; 146 147 up_fail: 148 mm->context.vdso = NULL; 149 return PTR_ERR(ret); 150 } 151 152 #ifdef CONFIG_COMPAT 153 int compat_arch_setup_additional_pages(struct linux_binprm *bprm, 154 int uses_interp) 155 { 156 struct mm_struct *mm = current->mm; 157 int ret; 158 159 if (mmap_write_lock_killable(mm)) 160 return -EINTR; 161 162 ret = __setup_additional_pages(mm, bprm, uses_interp, 163 &compat_vdso_info); 164 mmap_write_unlock(mm); 165 166 return ret; 167 } 168 #endif 169 170 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 171 { 172 struct mm_struct *mm = current->mm; 173 int ret; 174 175 if (mmap_write_lock_killable(mm)) 176 return -EINTR; 177 178 ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info); 179 mmap_write_unlock(mm); 180 181 return ret; 182 } 183