arch/um/kernel/skas/uaccess.c

   1 /*
   2  * Copyright (C) 2002 - 2003 Jeff Dike (jdike@addtoit.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/compiler.h"
   7 #include "linux/stddef.h"
   8 #include "linux/kernel.h"
   9 #include "linux/string.h"
  10 #include "linux/fs.h"
  11 #include "linux/hardirq.h"
  12 #include "linux/highmem.h"
  13 #include "asm/page.h"
  14 #include "asm/pgtable.h"
  15 #include "asm/uaccess.h"
  16 #include "kern_util.h"
  17 #include "os.h"
  18
  19 extern void *um_virt_to_phys(struct task_struct *task, unsigned long addr,
  20                              pte_t *pte_out);
  21
  22 static unsigned long maybe_map(unsigned long virt, int is_write)
  23 {
  24         pte_t pte;
  25         int err;
  26
  27         void *phys = um_virt_to_phys(current, virt, &pte);
  28         int dummy_code;
  29
  30         if(IS_ERR(phys) || (is_write && !pte_write(pte))){
  31                 err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
  32                 if(err)
  33                         return(-1UL);
  34                 phys = um_virt_to_phys(current, virt, NULL);
  35         }
  36         if(IS_ERR(phys))
  37                 phys = (void *) -1;
  38
  39         return((unsigned long) phys);
  40 }
  41
  42 static int do_op_one_page(unsigned long addr, int len, int is_write,
  43                  int (*op)(unsigned long addr, int len, void *arg), void *arg)
  44 {
  45         struct page *page;
  46         int n;
  47
  48         addr = maybe_map(addr, is_write);
  49         if(addr == -1UL)
  50                 return(-1);
  51
  52         page = phys_to_page(addr);
  53         addr = (unsigned long) kmap_atomic(page, KM_UML_USERCOPY) + (addr & ~PAGE_MASK);
  54
  55         n = (*op)(addr, len, arg);
  56
  57         kunmap_atomic(page, KM_UML_USERCOPY);
  58
  59         return(n);
  60 }
  61
  62 static void do_buffer_op(void *jmpbuf, void *arg_ptr)
  63 {
  64         va_list args;
  65         unsigned long addr;
  66         int len, is_write, size, remain, n;
  67         int (*op)(unsigned long, int, void *);
  68         void *arg;
  69         int *res;
  70
  71         va_copy(args, *(va_list *)arg_ptr);
  72         addr = va_arg(args, unsigned long);
  73         len = va_arg(args, int);
  74         is_write = va_arg(args, int);
  75         op = va_arg(args, void *);
  76         arg = va_arg(args, void *);
  77         res = va_arg(args, int *);
  78         va_end(args);
  79         size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
  80         remain = len;
  81
  82         current->thread.fault_catcher = jmpbuf;
  83         n = do_op_one_page(addr, size, is_write, op, arg);
  84         if(n != 0){
  85                 *res = (n < 0 ? remain : 0);
  86                 goto out;
  87         }
  88
  89         addr += size;
  90         remain -= size;
  91         if(remain == 0){
  92                 *res = 0;
  93                 goto out;
  94         }
  95
  96         while(addr < ((addr + remain) & PAGE_MASK)){
  97                 n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg);
  98                 if(n != 0){
  99                         *res = (n < 0 ? remain : 0);
 100                         goto out;
 101                 }
 102
 103                 addr += PAGE_SIZE;
 104                 remain -= PAGE_SIZE;
 105         }
 106         if(remain == 0){
 107                 *res = 0;
 108                 goto out;
 109         }
 110
 111         n = do_op_one_page(addr, remain, is_write, op, arg);
 112         if(n != 0)
 113                 *res = (n < 0 ? remain : 0);
 114         else *res = 0;
 115  out:
 116         current->thread.fault_catcher = NULL;
 117 }
 118
 119 static int buffer_op(unsigned long addr, int len, int is_write,
 120                      int (*op)(unsigned long addr, int len, void *arg),
 121                      void *arg)
 122 {
 123         int faulted, res;
 124
 125         faulted = setjmp_wrapper(do_buffer_op, addr, len, is_write, op, arg,
 126                                  &res);
 127         if(!faulted)
 128                 return(res);
 129
 130         return(addr + len - (unsigned long) current->thread.fault_addr);
 131 }
 132
 133 static int copy_chunk_from_user(unsigned long from, int len, void *arg)
 134 {
 135         unsigned long *to_ptr = arg, to = *to_ptr;
 136
 137         memcpy((void *) to, (void *) from, len);
 138         *to_ptr += len;
 139         return(0);
 140 }
 141
 142 int copy_from_user_skas(void *to, const void __user *from, int n)
 143 {
 144         if(segment_eq(get_fs(), KERNEL_DS)){
 145                 memcpy(to, (__force void*)from, n);
 146                 return(0);
 147         }
 148
 149         return(access_ok(VERIFY_READ, from, n) ?
 150                buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to):
 151                n);
 152 }
 153
 154 static int copy_chunk_to_user(unsigned long to, int len, void *arg)
 155 {
 156         unsigned long *from_ptr = arg, from = *from_ptr;
 157
 158         memcpy((void *) to, (void *) from, len);
 159         *from_ptr += len;
 160         return(0);
 161 }
 162
 163 int copy_to_user_skas(void __user *to, const void *from, int n)
 164 {
 165         if(segment_eq(get_fs(), KERNEL_DS)){
 166                 memcpy((__force void*)to, from, n);
 167                 return(0);
 168         }
 169
 170         return(access_ok(VERIFY_WRITE, to, n) ?
 171                buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from) :
 172                n);
 173 }
 174
 175 static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
 176 {
 177         char **to_ptr = arg, *to = *to_ptr;
 178         int n;
 179
 180         strncpy(to, (void *) from, len);
 181         n = strnlen(to, len);
 182         *to_ptr += n;
 183
 184         if(n < len)
 185                 return(1);
 186         return(0);
 187 }
 188
 189 int strncpy_from_user_skas(char *dst, const char __user *src, int count)
 190 {
 191         int n;
 192         char *ptr = dst;
 193
 194         if(segment_eq(get_fs(), KERNEL_DS)){
 195                 strncpy(dst, (__force void*)src, count);
 196                 return(strnlen(dst, count));
 197         }
 198
 199         if(!access_ok(VERIFY_READ, src, 1))
 200                 return(-EFAULT);
 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
 209 static int clear_chunk(unsigned long addr, int len, void *unused)
 210 {
 211         memset((void *) addr, 0, len);
 212         return(0);
 213 }
 214
 215 int __clear_user_skas(void __user *mem, int len)
 216 {
 217         return(buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL));
 218 }
 219
 220 int clear_user_skas(void __user *mem, int len)
 221 {
 222         if(segment_eq(get_fs(), KERNEL_DS)){
 223                 memset((__force void*)mem, 0, len);
 224                 return(0);
 225         }
 226
 227         return(access_ok(VERIFY_WRITE, mem, len) ?
 228                buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL) : len);
 229 }
 230
 231 static int strnlen_chunk(unsigned long str, int len, void *arg)
 232 {
 233         int *len_ptr = arg, n;
 234
 235         n = strnlen((void *) str, len);
 236         *len_ptr += n;
 237
 238         if(n < len)
 239                 return(1);
 240         return(0);
 241 }
 242
 243 int strnlen_user_skas(const void __user *str, int len)
 244 {
 245         int count = 0, n;
 246
 247         if(segment_eq(get_fs(), KERNEL_DS))
 248                 return(strnlen((__force char*)str, len) + 1);
 249
 250         n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count);
 251         if(n == 0)
 252                 return(count + 1);
 253         return(-EFAULT);
 254 }
 255
 256 /*
 257  * Overrides for Emacs so that we follow Linus's tabbing style.
 258  * Emacs will notice this stuff at the end of the file and automatically
 259  * adjust the settings for this buffer only.  This must remain at the end
 260  * of the file.
 261  * ---------------------------------------------------------------------------
 262  * Local variables:
 263  * c-file-style: "linux"
 264  * End:
 265  */