arch/um/kernel/skas/uaccess.c

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