kernel/exec_domain.c

   1 #include <linux/personality.h>
   2 #include <linux/ptrace.h>
   3 #include <linux/sched.h>
   4 #include <linux/mm.h>
   5 #include <linux/smp.h>
   6 #include <linux/smp_lock.h>
   7 #include <linux/module.h>
   8
   9 static asmlinkage void no_lcall7(struct pt_regs * regs);
  10
  11
  12 static unsigned long ident_map[32] = {
  13         0,      1,      2,      3,      4,      5,      6,      7,
  14         8,      9,      10,     11,     12,     13,     14,     15,
  15         16,     17,     18,     19,     20,     21,     22,     23,
  16         24,     25,     26,     27,     28,     29,     30,     31
  17 };
  18
  19 struct exec_domain default_exec_domain = {
  20         "Linux",        /* name */
  21         no_lcall7,      /* lcall7 causes a seg fault. */
  22         0, 0xff,        /* All personalities. */
  23         ident_map,      /* Identity map signals. */
  24         ident_map,      /*  - both ways. */
  25         NULL,           /* No usage counter. */
  26         NULL            /* Nothing after this in the list. */
  27 };
  28
  29 static struct exec_domain *exec_domains = &default_exec_domain;
  30
  31
  32 static asmlinkage void no_lcall7(struct pt_regs * regs)
  33 {
  34
  35   /*
  36    * This may have been a static linked SVr4 binary, so we would have the
  37    * personality set incorrectly.  Check to see whether SVr4 is available,
  38    * and use it, otherwise give the user a SEGV.
  39    */
  40         if (current->exec_domain && current->exec_domain->module)
  41                 __MOD_DEC_USE_COUNT(current->exec_domain->module);
  42
  43         current->personality = PER_SVR4;
  44         current->exec_domain = lookup_exec_domain(current->personality);
  45
  46         if (current->exec_domain && current->exec_domain->module)
  47                 __MOD_INC_USE_COUNT(current->exec_domain->module);
  48
  49         if (current->exec_domain && current->exec_domain->handler
  50         && current->exec_domain->handler != no_lcall7) {
  51                 current->exec_domain->handler(regs);
  52                 return;
  53         }
  54
  55         send_sig(SIGSEGV, current, 1);
  56 }
  57
  58 struct exec_domain *lookup_exec_domain(unsigned long personality)
  59 {
  60         unsigned long pers = personality & PER_MASK;
  61         struct exec_domain *it;
  62
  63         for (it=exec_domains; it; it=it->next)
  64                 if (pers >= it->pers_low
  65                 && pers <= it->pers_high)
  66                         return it;
  67
  68         /* Should never get this far. */
  69         printk(KERN_ERR "No execution domain for personality 0x%02lx\n", pers);
  70         return NULL;
  71 }
  72
  73 int register_exec_domain(struct exec_domain *it)
  74 {
  75         struct exec_domain *tmp;
  76
  77         if (!it)
  78                 return -EINVAL;
  79         if (it->next)
  80                 return -EBUSY;
  81         for (tmp=exec_domains; tmp; tmp=tmp->next)
  82                 if (tmp == it)
  83                         return -EBUSY;
  84         it->next = exec_domains;
  85         exec_domains = it;
  86         return 0;
  87 }
  88
  89 int unregister_exec_domain(struct exec_domain *it)
  90 {
  91         struct exec_domain ** tmp;
  92
  93         tmp = &exec_domains;
  94         while (*tmp) {
  95                 if (it == *tmp) {
  96                         *tmp = it->next;
  97                         it->next = NULL;
  98                         return 0;
  99                 }
 100                 tmp = &(*tmp)->next;
 101         }
 102         return -EINVAL;
 103 }
 104
 105 asmlinkage int sys_personality(unsigned long personality)
 106 {
 107         struct exec_domain *it;
 108         unsigned long old_personality;
 109         int ret;
 110
 111         lock_kernel();
 112         ret = current->personality;
 113         if (personality == 0xffffffff)
 114                 goto out;
 115
 116         ret = -EINVAL;
 117         it = lookup_exec_domain(personality);
 118         if (!it)
 119                 goto out;
 120
 121         old_personality = current->personality;
 122         if (current->exec_domain && current->exec_domain->module)
 123                 __MOD_DEC_USE_COUNT(current->exec_domain->module);
 124         current->personality = personality;
 125         current->exec_domain = it;
 126         if (current->exec_domain->module)
 127                 __MOD_INC_USE_COUNT(current->exec_domain->module);
 128         ret = old_personality;
 129 out:
 130         unlock_kernel();
 131         return ret;
 132 }