arch/um/sys-i386/ldt.c

   1 /*
   2  * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/config.h"
   7 #include "linux/sched.h"
   8 #include "linux/slab.h"
   9 #include "linux/types.h"
  10 #include "asm/uaccess.h"
  11 #include "asm/ptrace.h"
  12 #include "asm/smp.h"
  13 #include "asm/ldt.h"
  14 #include "choose-mode.h"
  15 #include "kern.h"
  16 #include "mode_kern.h"
  17
  18 #ifdef CONFIG_MODE_TT
  19
  20 extern int modify_ldt(int func, void *ptr, unsigned long bytecount);
  21
  22 static int do_modify_ldt_tt(int func, void *ptr, unsigned long bytecount)
  23 {
  24         return modify_ldt(func, ptr, bytecount);
  25 }
  26
  27 #endif
  28
  29 #ifdef CONFIG_MODE_SKAS
  30
  31 #include "skas.h"
  32 #include "skas_ptrace.h"
  33
  34 static int do_modify_ldt_skas(int func, void *ptr, unsigned long bytecount)
  35 {
  36         struct ptrace_ldt ldt;
  37         u32 cpu;
  38         int res;
  39
  40         ldt = ((struct ptrace_ldt) { .func      = func,
  41                                      .ptr       = ptr,
  42                                      .bytecount = bytecount });
  43
  44         cpu = get_cpu();
  45         res = ptrace(PTRACE_LDT, userspace_pid[cpu], 0, (unsigned long) &ldt);
  46         put_cpu();
  47
  48         return res;
  49 }
  50 #endif
  51
  52 int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
  53 {
  54         struct user_desc info;
  55         int res = 0;
  56         void *buf = NULL;
  57         void *p = NULL; /* What we pass to host. */
  58
  59         switch(func){
  60         case 1:
  61         case 0x11: /* write_ldt */
  62                 /* Do this check now to avoid overflows. */
  63                 if (bytecount != sizeof(struct user_desc)) {
  64                         res = -EINVAL;
  65                         goto out;
  66                 }
  67
  68                 if(copy_from_user(&info, ptr, sizeof(info))) {
  69                         res = -EFAULT;
  70                         goto out;
  71                 }
  72
  73                 p = &info;
  74                 break;
  75         case 0:
  76         case 2: /* read_ldt */
  77
  78                 /* The use of info avoids kmalloc on the write case, not on the
  79                  * read one. */
  80                 buf = kmalloc(bytecount, GFP_KERNEL);
  81                 if (!buf) {
  82                         res = -ENOMEM;
  83                         goto out;
  84                 }
  85                 p = buf;
  86                 break;
  87         default:
  88                 res = -ENOSYS;
  89                 goto out;
  90         }
  91
  92         res = CHOOSE_MODE_PROC(do_modify_ldt_tt, do_modify_ldt_skas, func,
  93                                 p, bytecount);
  94         if(res < 0)
  95                 goto out;
  96
  97         switch(func){
  98         case 0:
  99         case 2:
 100                 /* Modify_ldt was for reading and returned the number of read
 101                  * bytes.*/
 102                 if(copy_to_user(ptr, p, res))
 103                         res = -EFAULT;
 104                 break;
 105         }
 106
 107 out:
 108         kfree(buf);
 109         return res;
 110 }