kernel/exec_domain.c

   1 #include <linux/mm.h>
   2 #include <linux/smp_lock.h>
   3 #include <linux/module.h>
   4
   5 static asmlinkage void no_lcall7(struct pt_regs * regs);
   6
   7
   8 static unsigned long ident_map[32] = {
   9         0,      1,      2,      3,      4,      5,      6,      7,
  10         8,      9,      10,     11,     12,     13,     14,     15,
  11         16,     17,     18,     19,     20,     21,     22,     23,
  12         24,     25,     26,     27,     28,     29,     30,     31
  13 };
  14
  15 struct exec_domain default_exec_domain = {
  16         "Linux",        /* name */
  17         no_lcall7,      /* lcall7 causes a seg fault. */
  18         0, 0xff,        /* All personalities. */
  19         ident_map,      /* Identity map signals. */
  20         ident_map,      /*  - both ways. */
  21         NULL,           /* No usage counter. */
  22         NULL            /* Nothing after this in the list. */
  23 };
  24
  25 static struct exec_domain *exec_domains = &default_exec_domain;
  26
  27
  28 static asmlinkage void no_lcall7(struct pt_regs * regs)
  29 {
  30
  31   /*
  32    * This may have been a static linked SVr4 binary, so we would have the
  33    * personality set incorrectly.  Check to see whether SVr4 is available,
  34    * and use it, otherwise give the user a SEGV.
  35    */
  36         if (current->exec_domain && current->exec_domain->module)
  37                 __MOD_DEC_USE_COUNT(current->exec_domain->module);
  38
  39         current->personality = PER_SVR4;
  40         current->exec_domain = lookup_exec_domain(current->personality);
  41
  42         if (current->exec_domain && current->exec_domain->module)
  43                 __MOD_INC_USE_COUNT(current->exec_domain->module);
  44
  45         if (current->exec_domain && current->exec_domain->handler
  46         && current->exec_domain->handler != no_lcall7) {
  47                 current->exec_domain->handler(regs);
  48                 return;
  49         }
  50
  51         send_sig(SIGSEGV, current, 1);
  52 }
  53
  54 struct exec_domain *lookup_exec_domain(unsigned long personality)
  55 {
  56         unsigned long pers = personality & PER_MASK;
  57         struct exec_domain *it;
  58
  59         for (it=exec_domains; it; it=it->next)
  60                 if (pers >= it->pers_low
  61                 && pers <= it->pers_high)
  62                         return it;
  63
  64         /* Should never get this far. */
  65         printk(KERN_ERR "No execution domain for personality 0x%02lx\n", pers);
  66         return NULL;
  67 }
  68
  69 int register_exec_domain(struct exec_domain *it)
  70 {
  71         struct exec_domain *tmp;
  72
  73         if (!it)
  74                 return -EINVAL;
  75         if (it->next)
  76                 return -EBUSY;
  77         for (tmp=exec_domains; tmp; tmp=tmp->next)
  78                 if (tmp == it)
  79                         return -EBUSY;
  80         it->next = exec_domains;
  81         exec_domains = it;
  82         return 0;
  83 }
  84
  85 int unregister_exec_domain(struct exec_domain *it)
  86 {
  87         struct exec_domain ** tmp;
  88
  89         tmp = &exec_domains;
  90         while (*tmp) {
  91                 if (it == *tmp) {
  92                         *tmp = it->next;
  93                         it->next = NULL;
  94                         return 0;
  95                 }
  96                 tmp = &(*tmp)->next;
  97         }
  98         return -EINVAL;
  99 }
 100
 101 asmlinkage int sys_personality(unsigned long personality)
 102 {
 103         struct exec_domain *it;
 104         unsigned long old_personality;
 105         int ret;
 106
 107         lock_kernel();
 108         ret = current->personality;
 109         if (personality == 0xffffffff)
 110                 goto out;
 111
 112         ret = -EINVAL;
 113         it = lookup_exec_domain(personality);
 114         if (!it)
 115                 goto out;
 116
 117         old_personality = current->personality;
 118         if (current->exec_domain && current->exec_domain->module)
 119                 __MOD_DEC_USE_COUNT(current->exec_domain->module);
 120         current->personality = personality;
 121         current->exec_domain = it;
 122         if (current->exec_domain->module)
 123                 __MOD_INC_USE_COUNT(current->exec_domain->module);
 124         ret = old_personality;
 125 out:
 126         unlock_kernel();
 127         return ret;
 128 }