security/security.c

   1 /*
   2  * Security plug functions
   3  *
   4  * Copyright (C) 2001 WireX Communications, Inc <chris@wirex.com>
   5  * Copyright (C) 2001-2002 Greg Kroah-Hartman <greg@kroah.com>
   6  * Copyright (C) 2001 Networks Associates Technology, Inc <ssmalley@nai.com>
   7  *
   8  *      This program is free software; you can redistribute it and/or modify
   9  *      it under the terms of the GNU General Public License as published by
  10  *      the Free Software Foundation; either version 2 of the License, or
  11  *      (at your option) any later version.
  12  */
  13
  14 #include <linux/config.h>
  15 #include <linux/module.h>
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/sched.h>
  19 #include <linux/security.h>
  20
  21 #define SECURITY_SCAFFOLD_VERSION       "1.0.0"
  22
  23 /* things that live in dummy.c */
  24 extern struct security_operations dummy_security_ops;
  25 extern void security_fixup_ops (struct security_operations *ops);
  26
  27 struct security_operations *security_ops;       /* Initialized to NULL */
  28
  29 static inline int verify (struct security_operations *ops)
  30 {
  31         /* verify the security_operations structure exists */
  32         if (!ops) {
  33                 printk (KERN_INFO "Passed a NULL security_operations "
  34                         "pointer, %s failed.\n", __FUNCTION__);
  35                 return -EINVAL;
  36         }
  37         security_fixup_ops (ops);
  38         return 0;
  39 }
  40
  41 /**
  42  * security_scaffolding_startup - initialzes the security scaffolding framework
  43  *
  44  * This should be called early in the kernel initialization sequence.
  45  */
  46 int security_scaffolding_startup (void)
  47 {
  48         printk (KERN_INFO "Security Scaffold v" SECURITY_SCAFFOLD_VERSION
  49                 " initialized\n");
  50
  51         if (verify (&dummy_security_ops)) {
  52                 printk (KERN_ERR "%s could not verify "
  53                         "dummy_security_ops structure.\n", __FUNCTION__);
  54                 return -EIO;
  55         }
  56
  57         security_ops = &dummy_security_ops;
  58
  59         return 0;
  60 }
  61
  62 /**
  63  * register_security - registers a security framework with the kernel
  64  * @ops: a pointer to the struct security_options that is to be registered
  65  *
  66  * This function is to allow a security module to register itself with the
  67  * kernel security subsystem.  Some rudimentary checking is done on the @ops
  68  * value passed to this function.  A call to unregister_security() should be
  69  * done to remove this security_options structure from the kernel.
  70  *
  71  * If the @ops structure does not contain function pointers for all hooks in
  72  * the structure, or there is already a security module registered with the
  73  * kernel, an error will be returned.  Otherwise 0 is returned on success.
  74  */
  75 int register_security (struct security_operations *ops)
  76 {
  77         if (verify (ops)) {
  78                 printk (KERN_INFO "%s could not verify "
  79                         "security_operations structure.\n", __FUNCTION__);
  80                 return -EINVAL;
  81         }
  82
  83         if (security_ops != &dummy_security_ops) {
  84                 printk (KERN_INFO "There is already a security "
  85                         "framework initialized, %s failed.\n", __FUNCTION__);
  86                 return -EINVAL;
  87         }
  88
  89         security_ops = ops;
  90
  91         return 0;
  92 }
  93
  94 /**
  95  * unregister_security - unregisters a security framework with the kernel
  96  * @ops: a pointer to the struct security_options that is to be registered
  97  *
  98  * This function removes a struct security_operations variable that had
  99  * previously been registered with a successful call to register_security().
 100  *
 101  * If @ops does not match the valued previously passed to register_security()
 102  * an error is returned.  Otherwise the default security options is set to the
 103  * the dummy_security_ops structure, and 0 is returned.
 104  */
 105 int unregister_security (struct security_operations *ops)
 106 {
 107         if (ops != security_ops) {
 108                 printk (KERN_INFO "%s: trying to unregister "
 109                         "a security_opts structure that is not "
 110                         "registered, failing.\n", __FUNCTION__);
 111                 return -EINVAL;
 112         }
 113
 114         security_ops = &dummy_security_ops;
 115
 116         return 0;
 117 }
 118
 119 /**
 120  * mod_reg_security - allows security modules to be "stacked"
 121  * @name: a pointer to a string with the name of the security_options to be registered
 122  * @ops: a pointer to the struct security_options that is to be registered
 123  *
 124  * This function allows security modules to be stacked if the currently loaded
 125  * security module allows this to happen.  It passes the @name and @ops to the
 126  * register_security function of the currently loaded security module.
 127  *
 128  * The return value depends on the currently loaded security module, with 0 as
 129  * success.
 130  */
 131 int mod_reg_security (const char *name, struct security_operations *ops)
 132 {
 133         if (verify (ops)) {
 134                 printk (KERN_INFO "%s could not verify "
 135                         "security operations.\n", __FUNCTION__);
 136                 return -EINVAL;
 137         }
 138
 139         if (ops == security_ops) {
 140                 printk (KERN_INFO "%s security operations "
 141                         "already registered.\n", __FUNCTION__);
 142                 return -EINVAL;
 143         }
 144
 145         return security_ops->register_security (name, ops);
 146 }
 147
 148 /**
 149  * mod_unreg_security - allows a security module registered with mod_reg_security() to be unloaded
 150  * @name: a pointer to a string with the name of the security_options to be removed
 151  * @ops: a pointer to the struct security_options that is to be removed
 152  *
 153  * This function allows security modules that have been successfully registered
 154  * with a call to mod_reg_security() to be unloaded from the system.
 155  * This calls the currently loaded security module's unregister_security() call
 156  * with the @name and @ops variables.
 157  *
 158  * The return value depends on the currently loaded security module, with 0 as
 159  * success.
 160  */
 161 int mod_unreg_security (const char *name, struct security_operations *ops)
 162 {
 163         if (ops == security_ops) {
 164                 printk (KERN_INFO "%s invalid attempt to unregister "
 165                         " primary security ops.\n", __FUNCTION__);
 166                 return -EINVAL;
 167         }
 168
 169         return security_ops->unregister_security (name, ops);
 170 }
 171
 172 /**
 173  * capable - calls the currently loaded security module's capable() function with the specified capability
 174  * @cap: the requested capability level.
 175  *
 176  * This function calls the currently loaded security module's cabable()
 177  * function with a pointer to the current task and the specified @cap value.
 178  *
 179  * This allows the security module to implement the capable function call
 180  * however it chooses to.
 181  */
 182 int capable (int cap)
 183 {
 184         if (security_ops->capable (current, cap)) {
 185                 /* capability denied */
 186                 return 0;
 187         }
 188
 189         /* capability granted */
 190         current->flags |= PF_SUPERPRIV;
 191         return 1;
 192 }
 193
 194 EXPORT_SYMBOL_GPL(register_security);
 195 EXPORT_SYMBOL_GPL(unregister_security);
 196 EXPORT_SYMBOL_GPL(mod_reg_security);
 197 EXPORT_SYMBOL_GPL(mod_unreg_security);
 198 EXPORT_SYMBOL(capable);
 199 EXPORT_SYMBOL(security_ops);