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  1. /*
  2.  * Copyright (C) 2006 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /**
  30.  * @file    cap.c
  31.  * @brief   Capabilities control.
  32.  *
  33.  * @see cap.h
  34.  */
  35.  
  36. #include <security/cap.h>
  37. #include <proc/task.h>
  38. #include <synch/spinlock.h>
  39. #include <syscall/sysarg64.h>
  40. #include <syscall/copy.h>
  41. #include <arch.h>
  42. #include <typedefs.h>
  43. #include <errno.h>
  44.  
  45. /** Set capabilities.
  46.  *
  47.  * @param t Task whose capabilities are to be changed.
  48.  * @param caps New set of capabilities.
  49.  */
  50. void cap_set(task_t *t, cap_t caps)
  51. {
  52.     ipl_t ipl;
  53.    
  54.     ipl = interrupts_disable();
  55.     spinlock_lock(&t->lock);
  56.    
  57.     t->capabilities = caps;
  58.    
  59.     spinlock_unlock(&t->lock);
  60.     interrupts_restore(ipl);
  61. }
  62.  
  63. /** Get capabilities.
  64.  *
  65.  * @param t Task whose capabilities are to be returned.
  66.  * @return Task's capabilities.
  67.  */
  68. cap_t cap_get(task_t *t)
  69. {
  70.     ipl_t ipl;
  71.     cap_t caps;
  72.    
  73.     ipl = interrupts_disable();
  74.     spinlock_lock(&t->lock);
  75.    
  76.     caps = t->capabilities;
  77.    
  78.     spinlock_unlock(&t->lock);
  79.     interrupts_restore(ipl);
  80.    
  81.     return caps;
  82. }
  83.  
  84. /** Grant capabilities to a task.
  85.  *
  86.  * The calling task must have the CAP_CAP capability.
  87.  *
  88.  * @param uspace_taskid_arg Userspace structure holding destination task ID.
  89.  * @param caps Capabilities to grant.
  90.  *
  91.  * @return Zero on success or an error code from @ref errno.h.
  92.  */
  93. __native sys_cap_grant(sysarg64_t *uspace_taskid_arg, cap_t caps)
  94. {
  95.     sysarg64_t taskid_arg;
  96.     task_t *t;
  97.     ipl_t ipl;
  98.     int rc;
  99.    
  100.     if (!(cap_get(TASK) & CAP_CAP))
  101.         return (__native) EPERM;
  102.    
  103.     rc = copy_from_uspace(&taskid_arg, uspace_taskid_arg, sizeof(sysarg64_t));
  104.     if (rc != 0)
  105.         return (__native) rc;
  106.        
  107.     ipl = interrupts_disable();
  108.     spinlock_lock(&tasks_lock);
  109.     t = task_find_by_id((task_id_t) taskid_arg.value);
  110.     if (!t) {
  111.         spinlock_unlock(&tasks_lock);
  112.         interrupts_restore(ipl);
  113.         return (__native) ENOENT;
  114.     }
  115.     spinlock_unlock(&tasks_lock);
  116.    
  117.     cap_set(t, cap_get(t) | caps);
  118.    
  119.     interrupts_restore(ipl);   
  120.     return 0;
  121. }
  122.  
  123. /** Revoke capabilities from a task.
  124.  *
  125.  * The calling task must have the CAP_CAP capability or the caller must
  126.  * attempt to revoke capabilities from itself.
  127.  *
  128.  * @param uspace_taskid_arg Userspace structure holding destination task ID.
  129.  * @param caps Capabilities to revoke.
  130.  *
  131.  * @return Zero on success or an error code from @ref errno.h.
  132.  */
  133. __native sys_cap_revoke(sysarg64_t *uspace_taskid_arg, cap_t caps)
  134. {
  135.     sysarg64_t taskid_arg;
  136.     task_t *t;
  137.     ipl_t ipl;
  138.     int rc;
  139.    
  140.     rc = copy_from_uspace(&taskid_arg, uspace_taskid_arg, sizeof(sysarg64_t));
  141.     if (rc != 0)
  142.         return (__native) rc;
  143.  
  144.     ipl = interrupts_disable();
  145.     spinlock_lock(&tasks_lock);
  146.     t = task_find_by_id((task_id_t) taskid_arg.value);
  147.     if (!t) {
  148.         spinlock_unlock(&tasks_lock);
  149.         interrupts_restore(ipl);
  150.         return (__native) ENOENT;
  151.     }
  152.     spinlock_unlock(&tasks_lock);
  153.  
  154.     /*
  155.      * Revoking capabilities is different from granting them in that
  156.      * a task can revoke capabilities from itself even if it
  157.      * doesn't have CAP_CAP.
  158.      */
  159.     if (!(cap_get(TASK) & CAP_CAP) || !(t == TASK)) {
  160.         interrupts_restore(ipl);
  161.         return (__native) EPERM;
  162.     }
  163.  
  164.     cap_set(t, cap_get(t) & ~caps);
  165.    
  166.     interrupts_restore(ipl);
  167.     return 0;
  168. }
  169.