1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 4 */ 5 6 #include <linux/err.h> 7 #include <linux/highmem.h> 8 #include <linux/mm.h> 9 #include <linux/module.h> 10 #include <linux/sched.h> 11 #include <asm/current.h> 12 #include <asm/page.h> 13 #include <asm/pgtable.h> 14 #include <kern_util.h> 15 #include <os.h> 16 17 pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr) 18 { 19 pgd_t *pgd; 20 p4d_t *p4d; 21 pud_t *pud; 22 pmd_t *pmd; 23 24 if (mm == NULL) 25 return NULL; 26 27 pgd = pgd_offset(mm, addr); 28 if (!pgd_present(*pgd)) 29 return NULL; 30 31 p4d = p4d_offset(pgd, addr); 32 if (!p4d_present(*p4d)) 33 return NULL; 34 35 pud = pud_offset(p4d, addr); 36 if (!pud_present(*pud)) 37 return NULL; 38 39 pmd = pmd_offset(pud, addr); 40 if (!pmd_present(*pmd)) 41 return NULL; 42 43 return pte_offset_kernel(pmd, addr); 44 } 45 46 static pte_t *maybe_map(unsigned long virt, int is_write) 47 { 48 pte_t *pte = virt_to_pte(current->mm, virt); 49 int err, dummy_code; 50 51 if ((pte == NULL) || !pte_present(*pte) || 52 (is_write && !pte_write(*pte))) { 53 err = handle_page_fault(virt, 0, is_write, 1, &dummy_code); 54 if (err) 55 return NULL; 56 pte = virt_to_pte(current->mm, virt); 57 } 58 if (!pte_present(*pte)) 59 pte = NULL; 60 61 return pte; 62 } 63 64 static int do_op_one_page(unsigned long addr, int len, int is_write, 65 int (*op)(unsigned long addr, int len, void *arg), void *arg) 66 { 67 struct page *page; 68 pte_t *pte; 69 int n; 70 71 pte = maybe_map(addr, is_write); 72 if (pte == NULL) 73 return -1; 74 75 page = pte_page(*pte); 76 #ifdef CONFIG_64BIT 77 pagefault_disable(); 78 addr = (unsigned long) page_address(page) + 79 (addr & ~PAGE_MASK); 80 #else 81 addr = (unsigned long) kmap_atomic(page) + 82 (addr & ~PAGE_MASK); 83 #endif 84 n = (*op)(addr, len, arg); 85 86 #ifdef CONFIG_64BIT 87 pagefault_enable(); 88 #else 89 kunmap_atomic((void *)addr); 90 #endif 91 92 return n; 93 } 94 95 static long buffer_op(unsigned long addr, int len, int is_write, 96 int (*op)(unsigned long, int, void *), void *arg) 97 { 98 long size, remain, n; 99 100 size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len); 101 remain = len; 102 103 n = do_op_one_page(addr, size, is_write, op, arg); 104 if (n != 0) { 105 remain = (n < 0 ? remain : 0); 106 goto out; 107 } 108 109 addr += size; 110 remain -= size; 111 if (remain == 0) 112 goto out; 113 114 while (addr < ((addr + remain) & PAGE_MASK)) { 115 n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg); 116 if (n != 0) { 117 remain = (n < 0 ? remain : 0); 118 goto out; 119 } 120 121 addr += PAGE_SIZE; 122 remain -= PAGE_SIZE; 123 } 124 if (remain == 0) 125 goto out; 126 127 n = do_op_one_page(addr, remain, is_write, op, arg); 128 if (n != 0) { 129 remain = (n < 0 ? remain : 0); 130 goto out; 131 } 132 133 return 0; 134 out: 135 return remain; 136 } 137 138 static int copy_chunk_from_user(unsigned long from, int len, void *arg) 139 { 140 unsigned long *to_ptr = arg, to = *to_ptr; 141 142 memcpy((void *) to, (void *) from, len); 143 *to_ptr += len; 144 return 0; 145 } 146 147 unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n) 148 { 149 if (uaccess_kernel()) { 150 memcpy(to, (__force void*)from, n); 151 return 0; 152 } 153 154 return buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to); 155 } 156 EXPORT_SYMBOL(raw_copy_from_user); 157 158 static int copy_chunk_to_user(unsigned long to, int len, void *arg) 159 { 160 unsigned long *from_ptr = arg, from = *from_ptr; 161 162 memcpy((void *) to, (void *) from, len); 163 *from_ptr += len; 164 return 0; 165 } 166 167 unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n) 168 { 169 if (uaccess_kernel()) { 170 memcpy((__force void *) to, from, n); 171 return 0; 172 } 173 174 return buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from); 175 } 176 EXPORT_SYMBOL(raw_copy_to_user); 177 178 static int strncpy_chunk_from_user(unsigned long from, int len, void *arg) 179 { 180 char **to_ptr = arg, *to = *to_ptr; 181 int n; 182 183 strncpy(to, (void *) from, len); 184 n = strnlen(to, len); 185 *to_ptr += n; 186 187 if (n < len) 188 return 1; 189 return 0; 190 } 191 192 long __strncpy_from_user(char *dst, const char __user *src, long count) 193 { 194 long n; 195 char *ptr = dst; 196 197 if (uaccess_kernel()) { 198 strncpy(dst, (__force void *) src, count); 199 return strnlen(dst, count); 200 } 201 202 n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user, 203 &ptr); 204 if (n != 0) 205 return -EFAULT; 206 return strnlen(dst, count); 207 } 208 EXPORT_SYMBOL(__strncpy_from_user); 209 210 static int clear_chunk(unsigned long addr, int len, void *unused) 211 { 212 memset((void *) addr, 0, len); 213 return 0; 214 } 215 216 unsigned long __clear_user(void __user *mem, unsigned long len) 217 { 218 if (uaccess_kernel()) { 219 memset((__force void*)mem, 0, len); 220 return 0; 221 } 222 223 return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL); 224 } 225 EXPORT_SYMBOL(__clear_user); 226 227 static int strnlen_chunk(unsigned long str, int len, void *arg) 228 { 229 int *len_ptr = arg, n; 230 231 n = strnlen((void *) str, len); 232 *len_ptr += n; 233 234 if (n < len) 235 return 1; 236 return 0; 237 } 238 239 long __strnlen_user(const void __user *str, long len) 240 { 241 int count = 0, n; 242 243 if (uaccess_kernel()) 244 return strnlen((__force char*)str, len) + 1; 245 246 n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count); 247 if (n == 0) 248 return count + 1; 249 return 0; 250 } 251 EXPORT_SYMBOL(__strnlen_user); 252