/*
   * linux/kernel/capability.c
   *
   * Copyright (C) 1997  Andrew Main <zefram@fysh.org>
   *
   * Integrated into 2.1.97+,  Andrew G. Morgan <morgan@transmeta.com>
   * 30 May 2002:	Cleanup, Robert M. Love <rml@tech9.net>
   */ 

  #include <linux/capability.h>

  #include <linux/mm.h>
  #include <linux/module.h>
  #include <linux/security.h>
  #include <linux/syscalls.h>
  #include <asm/uaccess.h>
  
  unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
  kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  
  EXPORT_SYMBOL(securebits);
  EXPORT_SYMBOL(cap_bset);
  
  /*
   * This lock protects task->cap_* for all tasks including current.
   * Locking rule: acquire this prior to tasklist_lock.
   */
  static DEFINE_SPINLOCK(task_capability_lock);
  
  /*
   * For sys_getproccap() and sys_setproccap(), any of the three
   * capability set pointers may be NULL -- indicating that that set is
   * uninteresting and/or not to be changed.
   */

  /**

   * sys_capget - get the capabilities of a given process.

   * @header: pointer to struct that contains capability version and
   *	target pid data
   * @dataptr: pointer to struct that contains the effective, permitted,
   *	and inheritable capabilities that are returned
   *
   * Returns 0 on success and < 0 on error.

   */
  asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  {
       int ret = 0;
       pid_t pid;
       __u32 version;

       struct task_struct *target;

       struct __user_cap_data_struct data;
  
       if (get_user(version, &header->version))
  	     return -EFAULT;
  
       if (version != _LINUX_CAPABILITY_VERSION) {
  	     if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  		     return -EFAULT; 
               return -EINVAL;
       }
  
       if (get_user(pid, &header->pid))
  	     return -EFAULT;
  
       if (pid < 0) 
               return -EINVAL;
  
       spin_lock(&task_capability_lock);
       read_lock(&tasklist_lock); 
  
       if (pid && pid != current->pid) {
  	     target = find_task_by_pid(pid);
  	     if (!target) {
  	          ret = -ESRCH;
  	          goto out;
  	     }
       } else
  	     target = current;
  
       ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
  
  out:
       read_unlock(&tasklist_lock); 
       spin_unlock(&task_capability_lock);
  
       if (!ret && copy_to_user(dataptr, &data, sizeof data))
            return -EFAULT; 
  
       return ret;
  }
  
  /*
   * cap_set_pg - set capabilities for all processes in a given process
   * group.  We call this holding task_capability_lock and tasklist_lock.
   */
  static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
  			      kernel_cap_t *inheritable,
  			      kernel_cap_t *permitted)
  {

  	struct task_struct *g, *target;

  	int ret = -EPERM;
  	int found = 0;
  
  	do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
  		target = g;
  		while_each_thread(g, target) {
  			if (!security_capset_check(target, effective,
  							inheritable,
  							permitted)) {
  				security_capset_set(target, effective,
  							inheritable,
  							permitted);
  				ret = 0;
  			}
  			found = 1;
  		}
  	} while_each_task_pid(pgrp, PIDTYPE_PGID, g);
  
  	if (!found)
  	     ret = 0;
  	return ret;
  }
  
  /*
   * cap_set_all - set capabilities for all processes other than init
   * and self.  We call this holding task_capability_lock and tasklist_lock.
   */
  static inline int cap_set_all(kernel_cap_t *effective,
  			       kernel_cap_t *inheritable,
  			       kernel_cap_t *permitted)
  {

       struct task_struct *g, *target;

       int ret = -EPERM;
       int found = 0;
  
       do_each_thread(g, target) {

               if (target == current || is_init(target))

                       continue;
               found = 1;
  	     if (security_capset_check(target, effective, inheritable,
  						permitted))
  		     continue;
  	     ret = 0;
  	     security_capset_set(target, effective, inheritable, permitted);
       } while_each_thread(g, target);
  
       if (!found)
  	     ret = 0;
       return ret;
  }

  /**
   * sys_capset - set capabilities for a process or a group of processes
   * @header: pointer to struct that contains capability version and
   *	target pid data
   * @data: pointer to struct that contains the effective, permitted,
   *	and inheritable capabilities
   *
   * Set capabilities for a given process, all processes, or all

   * processes in a given process group.
   *
   * The restrictions on setting capabilities are specified as:
   *
   * [pid is for the 'target' task.  'current' is the calling task.]
   *
   * I: any raised capabilities must be a subset of the (old current) permitted
   * P: any raised capabilities must be a subset of the (old current) permitted
   * E: must be set to a subset of (new target) permitted

   *
   * Returns 0 on success and < 0 on error.

   */
  asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
  {
       kernel_cap_t inheritable, permitted, effective;
       __u32 version;

       struct task_struct *target;

       int ret;
       pid_t pid;
  
       if (get_user(version, &header->version))
  	     return -EFAULT; 
  
       if (version != _LINUX_CAPABILITY_VERSION) {
  	     if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  		     return -EFAULT; 
               return -EINVAL;
       }
  
       if (get_user(pid, &header->pid))
  	     return -EFAULT; 
  
       if (pid && pid != current->pid && !capable(CAP_SETPCAP))
               return -EPERM;
  
       if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
  	 copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
  	 copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
  	     return -EFAULT; 
  
       spin_lock(&task_capability_lock);
       read_lock(&tasklist_lock);
  
       if (pid > 0 && pid != current->pid) {
            target = find_task_by_pid(pid);
            if (!target) {
                 ret = -ESRCH;
                 goto out;
            }
       } else
                 target = current;
  
       ret = 0;
  
       /* having verified that the proposed changes are legal,
             we now put them into effect. */
       if (pid < 0) {
               if (pid == -1)  /* all procs other than current and init */
                       ret = cap_set_all(&effective, &inheritable, &permitted);
  
               else            /* all procs in process group */
                       ret = cap_set_pg(-pid, &effective, &inheritable,
  		     					&permitted);
       } else {
  	     ret = security_capset_check(target, &effective, &inheritable,
  	     						&permitted);
  	     if (!ret)
  		     security_capset_set(target, &effective, &inheritable,
  		     					&permitted);
       }
  
  out:
       read_unlock(&tasklist_lock);
       spin_unlock(&task_capability_lock);
  
       return ret;
  }

  
  int __capable(struct task_struct *t, int cap)
  {
  	if (security_capable(t, cap) == 0) {
  		t->flags |= PF_SUPERPRIV;
  		return 1;
  	}
  	return 0;
  }
  EXPORT_SYMBOL(__capable);
  
  int capable(int cap)
  {
  	return __capable(current, cap);
  }
  EXPORT_SYMBOL(capable);