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1174 jermar 1 
/*
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 * Copyright (C) 2006 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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1264 jermar 29 
/**
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 * @file    cap.c
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 * @brief   Capabilities control.
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 *
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 * @see cap.h
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 */
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1174 jermar 36 
#include <security/cap.h>
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#include <proc/task.h>
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#include <synch/spinlock.h>
1297 jermar 39 
#include <syscall/sysarg64.h>
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#include <syscall/copy.h>
1174 jermar 41 
#include <arch.h>
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#include <typedefs.h>
1297 jermar 43 
#include <errno.h>
1174 jermar 44 
 
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/** Set capabilities.
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 *
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 * @param t Task whose capabilities are to be changed.
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 * @param caps New set of capabilities.
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 */
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void cap_set(task_t *t, cap_t caps)
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{
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    ipl_t ipl;
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    ipl = interrupts_disable();
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    spinlock_lock(&t->lock);
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    t->capabilities = caps;
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    spinlock_unlock(&t->lock);
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    interrupts_restore(ipl);
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}
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/** Get capabilities.
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 *
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 * @param t Task whose capabilities are to be returned.
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 * @return Task's capabilities.
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 */
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cap_t cap_get(task_t *t)
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{
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    ipl_t ipl;
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    cap_t caps;
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    ipl = interrupts_disable();
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    spinlock_lock(&t->lock);
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    caps = t->capabilities;
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    spinlock_unlock(&t->lock);
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    interrupts_restore(ipl);
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    return caps;
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}
1297 jermar 83 
 
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/** Grant capabilities to a task.
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 *
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 * The calling task must have the CAP_CAP capability.
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 *
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 * @param uspace_taskid_arg Userspace structure holding destination task ID.
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 * @param caps Capabilities to grant.
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 *
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 * @return Zero on success or an error code from @ref errno.h.
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 */
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__native sys_cap_grant(sysarg64_t *uspace_taskid_arg, cap_t caps)
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{
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    sysarg64_t taskid_arg;
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    task_t *t;
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    ipl_t ipl;
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    int rc;
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    if (!(cap_get(TASK) & CAP_CAP))
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        return (__native) EPERM;
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    rc = copy_from_uspace(&taskid_arg, uspace_taskid_arg, sizeof(sysarg64_t));
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    if (rc != 0)
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        return (__native) rc;
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    ipl = interrupts_disable();
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    spinlock_lock(&tasks_lock);
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    t = task_find_by_id((task_id_t) taskid_arg.value);
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    if (!t) {
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        spinlock_unlock(&tasks_lock);
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        interrupts_restore(ipl);
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        return (__native) ENOENT;
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    }
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    spinlock_unlock(&tasks_lock);
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    cap_set(t, cap_get(t) | caps);
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    interrupts_restore(ipl);   
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    return 0;
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}
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/** Revoke capabilities from a task.
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 *
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 * The calling task must have the CAP_CAP capability or the caller must
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 * attempt to revoke capabilities from itself.
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 *
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 * @param uspace_taskid_arg Userspace structure holding destination task ID.
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 * @param caps Capabilities to revoke.
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 *
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 * @return Zero on success or an error code from @ref errno.h.
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 */
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__native sys_cap_revoke(sysarg64_t *uspace_taskid_arg, cap_t caps)
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{
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    sysarg64_t taskid_arg;
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    task_t *t;
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    ipl_t ipl;
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    int rc;
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    rc = copy_from_uspace(&taskid_arg, uspace_taskid_arg, sizeof(sysarg64_t));
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    if (rc != 0)
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        return (__native) rc;
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    ipl = interrupts_disable();
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    spinlock_lock(&tasks_lock);
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    t = task_find_by_id((task_id_t) taskid_arg.value);
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    if (!t) {
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        spinlock_unlock(&tasks_lock);
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        interrupts_restore(ipl);
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        return (__native) ENOENT;
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    }
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    spinlock_unlock(&tasks_lock);
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    /*
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     * Revoking capabilities is different from granting them in that
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     * a task can revoke capabilities from itself even if it
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     * doesn't have CAP_CAP.
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     */
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    if (!(cap_get(TASK) & CAP_CAP) || !(t == TASK)) {
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        interrupts_restore(ipl);
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        return (__native) EPERM;
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    }
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    cap_set(t, cap_get(t) & ~caps);
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    interrupts_restore(ipl);
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    return 0;
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}