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 static void __init do_security_initcalls(void)
  42 {
  43         initcall_t *call;
  44         call = &__security_initcall_start;
  45         while (call < &__security_initcall_end) {
  46                 (*call)();
  47                 call++;
  48         }
  49 }
  50
  51 /**
  52  * security_scaffolding_startup - initializes the security scaffolding framework
  53  *
  54  * This should be called early in the kernel initialization sequence.
  55  */
  56 int __init security_scaffolding_startup (void)
  57 {
  58         printk (KERN_INFO "Security Scaffold v" SECURITY_SCAFFOLD_VERSION
  59                 " initialized\n");
  60
  61         if (verify (&dummy_security_ops)) {
  62                 printk (KERN_ERR "%s could not verify "
  63                         "dummy_security_ops structure.\n", __FUNCTION__);
  64                 return -EIO;
  65         }
  66
  67         security_ops = &dummy_security_ops;
  68         do_security_initcalls();
  69
  70         return 0;
  71 }
  72
  73 /**
  74  * register_security - registers a security framework with the kernel
  75  * @ops: a pointer to the struct security_options that is to be registered
  76  *
  77  * This function is to allow a security module to register itself with the
  78  * kernel security subsystem.  Some rudimentary checking is done on the @ops
  79  * value passed to this function.  A call to unregister_security() should be
  80  * done to remove this security_options structure from the kernel.
  81  *
  82  * If there is already a security module registered with the kernel,
  83  * an error will be returned.  Otherwise 0 is returned on success.
  84  */
  85 int register_security (struct security_operations *ops)
  86 {
  87         if (verify (ops)) {
  88                 printk (KERN_INFO "%s could not verify "
  89                         "security_operations structure.\n", __FUNCTION__);
  90                 return -EINVAL;
  91         }
  92
  93         if (security_ops != &dummy_security_ops) {
  94                 printk (KERN_INFO "There is already a security "
  95                         "framework initialized, %s failed.\n", __FUNCTION__);
  96                 return -EINVAL;
  97         }
  98
  99         security_ops = ops;
 100
 101         return 0;
 102 }
 103
 104 /**
 105  * unregister_security - unregisters a security framework with the kernel
 106  * @ops: a pointer to the struct security_options that is to be registered
 107  *
 108  * This function removes a struct security_operations variable that had
 109  * previously been registered with a successful call to register_security().
 110  *
 111  * If @ops does not match the valued previously passed to register_security()
 112  * an error is returned.  Otherwise the default security options is set to the
 113  * the dummy_security_ops structure, and 0 is returned.
 114  */
 115 int unregister_security (struct security_operations *ops)
 116 {
 117         if (ops != security_ops) {
 118                 printk (KERN_INFO "%s: trying to unregister "
 119                         "a security_opts structure that is not "
 120                         "registered, failing.\n", __FUNCTION__);
 121                 return -EINVAL;
 122         }
 123
 124         security_ops = &dummy_security_ops;
 125
 126         return 0;
 127 }
 128
 129 /**
 130  * mod_reg_security - allows security modules to be "stacked"
 131  * @name: a pointer to a string with the name of the security_options to be registered
 132  * @ops: a pointer to the struct security_options that is to be registered
 133  *
 134  * This function allows security modules to be stacked if the currently loaded
 135  * security module allows this to happen.  It passes the @name and @ops to the
 136  * register_security function of the currently loaded security module.
 137  *
 138  * The return value depends on the currently loaded security module, with 0 as
 139  * success.
 140  */
 141 int mod_reg_security (const char *name, struct security_operations *ops)
 142 {
 143         if (verify (ops)) {
 144                 printk (KERN_INFO "%s could not verify "
 145                         "security operations.\n", __FUNCTION__);
 146                 return -EINVAL;
 147         }
 148
 149         if (ops == security_ops) {
 150                 printk (KERN_INFO "%s security operations "
 151                         "already registered.\n", __FUNCTION__);
 152                 return -EINVAL;
 153         }
 154
 155         return security_ops->register_security (name, ops);
 156 }
 157
 158 /**
 159  * mod_unreg_security - allows a security module registered with mod_reg_security() to be unloaded
 160  * @name: a pointer to a string with the name of the security_options to be removed
 161  * @ops: a pointer to the struct security_options that is to be removed
 162  *
 163  * This function allows security modules that have been successfully registered
 164  * with a call to mod_reg_security() to be unloaded from the system.
 165  * This calls the currently loaded security module's unregister_security() call
 166  * with the @name and @ops variables.
 167  *
 168  * The return value depends on the currently loaded security module, with 0 as
 169  * success.
 170  */
 171 int mod_unreg_security (const char *name, struct security_operations *ops)
 172 {
 173         if (ops == security_ops) {
 174                 printk (KERN_INFO "%s invalid attempt to unregister "
 175                         " primary security ops.\n", __FUNCTION__);
 176                 return -EINVAL;
 177         }
 178
 179         return security_ops->unregister_security (name, ops);
 180 }
 181
 182 /**
 183  * capable - calls the currently loaded security module's capable() function with the specified capability
 184  * @cap: the requested capability level.
 185  *
 186  * This function calls the currently loaded security module's capable()
 187  * function with a pointer to the current task and the specified @cap value.
 188  *
 189  * This allows the security module to implement the capable function call
 190  * however it chooses to.
 191  */
 192 int capable (int cap)
 193 {
 194         if (security_ops->capable (current, cap)) {
 195                 /* capability denied */
 196                 return 0;
 197         }
 198
 199         /* capability granted */
 200         current->flags |= PF_SUPERPRIV;
 201         return 1;
 202 }
 203
 204 EXPORT_SYMBOL_GPL(register_security);
 205 EXPORT_SYMBOL_GPL(unregister_security);
 206 EXPORT_SYMBOL_GPL(mod_reg_security);
 207 EXPORT_SYMBOL_GPL(mod_unreg_security);
 208 EXPORT_SYMBOL(capable);
 209 EXPORT_SYMBOL(security_ops);