Index: kernel/generic/src/security/perm.c
===================================================================
--- kernel/generic/src/security/perm.c	(revision 719a208dbe29f92f5690472a3500c890db8f3f1f)
+++ kernel/generic/src/security/perm.c	(revision 719a208dbe29f92f5690472a3500c890db8f3f1f)
@@ -0,0 +1,229 @@
+/*
+ * Copyright (c) 2006 Jakub Jermar
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup generic
+ * @{
+ */
+
+/**
+ * @file perm.c
+ * @brief Task permissions control.
+ *
+ * @see perm.h
+ */
+
+#include <security/perm.h>
+#include <proc/task.h>
+#include <synch/spinlock.h>
+#include <syscall/copy.h>
+#include <arch.h>
+#include <errno.h>
+
+/** Set permissions.
+ *
+ * @param task  Task whose permissions are to be changed.
+ * @param perms New set of permissions.
+ *
+ */
+void perm_set(task_t *task, perm_t perms)
+{
+	irq_spinlock_lock(&task->lock, true);
+	task->perms = perms;
+	irq_spinlock_unlock(&task->lock, true);
+}
+
+/** Get permissions.
+ *
+ * @param task Task whose permissions are to be returned.
+ *
+ * @return Task's permissions.
+ *
+ */
+perm_t perm_get(task_t *task)
+{
+	irq_spinlock_lock(&task->lock, true);
+	perm_t perms = task->perms;
+	irq_spinlock_unlock(&task->lock, true);
+	
+	return perms;
+}
+
+/** Grant permissions to a task.
+ *
+ * The calling task must have the PERM_PERM permission.
+ *
+ * @param taskid Destination task ID.
+ * @param perms   Permissions to grant.
+ *
+ * @return Zero on success or an error code from @ref errno.h.
+ *
+ */
+static sysarg_t perm_grant(task_id_t taskid, perm_t perms)
+{
+	if (!(perm_get(TASK) & PERM_PERM))
+		return (sysarg_t) EPERM;
+	
+	irq_spinlock_lock(&tasks_lock, true);
+	task_t *task = task_find_by_id(taskid);
+	
+	if ((!task) || (!container_check(CONTAINER, task->container))) {
+		irq_spinlock_unlock(&tasks_lock, true);
+		return (sysarg_t) ENOENT;
+	}
+	
+	irq_spinlock_lock(&task->lock, false);
+	task->perms |= perms;
+	irq_spinlock_unlock(&task->lock, false);
+	
+	irq_spinlock_unlock(&tasks_lock, true);
+	return 0;
+}
+
+/** Revoke permissions from a task.
+ *
+ * The calling task must have the PERM_PERM permission or the caller must
+ * attempt to revoke permissions from itself.
+ *
+ * @param taskid Destination task ID.
+ * @param perms   Permissions to revoke.
+ *
+ * @return Zero on success or an error code from @ref errno.h.
+ *
+ */
+static sysarg_t perm_revoke(task_id_t taskid, perm_t perms)
+{
+	irq_spinlock_lock(&tasks_lock, true);
+	
+	task_t *task = task_find_by_id(taskid);
+	if ((!task) || (!container_check(CONTAINER, task->container))) {
+		irq_spinlock_unlock(&tasks_lock, true);
+		return (sysarg_t) ENOENT;
+	}
+	
+	/*
+	 * Revoking permissions is different from granting them in that
+	 * a task can revoke permissions from itself even if it
+	 * doesn't have PERM_PERM.
+	 */
+	irq_spinlock_unlock(&TASK->lock, false);
+	
+	if ((!(TASK->perms & PERM_PERM)) || (task != TASK)) {
+		irq_spinlock_unlock(&TASK->lock, false);
+		irq_spinlock_unlock(&tasks_lock, true);
+		return (sysarg_t) EPERM;
+	}
+	
+	task->perms &= ~perms;
+	irq_spinlock_unlock(&TASK->lock, false);
+	
+	irq_spinlock_unlock(&tasks_lock, true);
+	return 0;
+}
+
+#ifdef __32_BITS__
+
+/** Grant permissions to a task (32 bits)
+ *
+ * The calling task must have the PERM_PERM permission.
+ *
+ * @param uspace_taskid User-space pointer to destination task ID.
+ * @param perms         Permissions to grant.
+ *
+ * @return Zero on success or an error code from @ref errno.h.
+ *
+ */
+sysarg_t sys_perm_grant(sysarg64_t *uspace_taskid, perm_t perms)
+{
+	sysarg64_t taskid;
+	int rc = copy_from_uspace(&taskid, uspace_taskid, sizeof(sysarg64_t));
+	if (rc != 0)
+		return (sysarg_t) rc;
+	
+	return perm_grant((task_id_t) taskid, perms);
+}
+
+/** Revoke permissions from a task (32 bits)
+ *
+ * The calling task must have the PERM_PERM permission or the caller must
+ * attempt to revoke permissions from itself.
+ *
+ * @param uspace_taskid User-space pointer to destination task ID.
+ * @param perms         Perms to revoke.
+ *
+ * @return Zero on success or an error code from @ref errno.h.
+ *
+ */
+sysarg_t sys_perm_revoke(sysarg64_t *uspace_taskid, perm_t perms)
+{
+	sysarg64_t taskid;
+	int rc = copy_from_uspace(&taskid, uspace_taskid, sizeof(sysarg64_t));
+	if (rc != 0)
+		return (sysarg_t) rc;
+	
+	return perm_revoke((task_id_t) taskid, perms);
+}
+
+#endif  /* __32_BITS__ */
+
+#ifdef __64_BITS__
+
+/** Grant permissions to a task (64 bits)
+ *
+ * The calling task must have the PERM_PERM permission.
+ *
+ * @param taskid Destination task ID.
+ * @param perms  Permissions to grant.
+ *
+ * @return Zero on success or an error code from @ref errno.h.
+ *
+ */
+sysarg_t sys_perm_grant(sysarg_t taskid, perm_t perms)
+{
+	return perm_grant((task_id_t) taskid, perms);
+}
+
+/** Revoke permissions from a task (64 bits)
+ *
+ * The calling task must have the PERM_PERM permission or the caller must
+ * attempt to revoke permissions from itself.
+ *
+ * @param taskid Destination task ID.
+ * @param perms  Permissions to revoke.
+ *
+ * @return Zero on success or an error code from @ref errno.h.
+ *
+ */
+sysarg_t sys_perm_revoke(sysarg_t taskid, perm_t perms)
+{
+	return perm_revoke((task_id_t) taskid, perms);
+}
+
+#endif  /* __64_BITS__ */
+
+/** @}
+ */
