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kernel: add k_object_access_revoke() system call

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Does the opposite of k_object_access_grant(); the provided thread will
lose access to that kernel object.

If invoked from userspace the caller must hace sufficient access
to that object and permission on the thread being revoked access.

Fix documentation for k_object_access_grant() API to reflect that
permission on the thread parameter is needed as well.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
Andrew Boie 2017-10-09 14:47:55 -07:00 • committed by Andrew Boie
commit a89bf01192
4 changed files with 56 additions and 1 deletions
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20
include/kernel.h
View file

@ -204,6 +204,13 @@ static inline void _impl_k_object_access_grant(void *object,
ARG_UNUSED(thread);
}
static inline void _impl_k_object_access_revoke(void *object,
struct k_thread *thread)
{
ARG_UNUSED(object);
ARG_UNUSED(thread);
}
static inline void _impl_k_object_access_all_grant(void *object)
{
ARG_UNUSED(object);
@ -215,13 +222,24 @@ static inline void _impl_k_object_access_all_grant(void *object)
*
* The thread will be granted access to the object if the caller is from
* supervisor mode, or the caller is from user mode AND has permissions
* on the object already.
* on both the object and the thread whose access is being granted.
*
* @param object Address of kernel object
* @param thread Thread to grant access to the object
*/
__syscall void k_object_access_grant(void *object, struct k_thread *thread);
/**
* grant a thread access to a kernel object
*
* The thread will lose access to the object if the caller is from
* supervisor mode, or the caller is from user mode AND has permissions
* on both the object and the thread whose access is being revoked.
*
* @param object Address of kernel object
* @param thread Thread to remove access to the object
*/
__syscall void k_object_access_revoke(void *object, struct k_thread *thread);
/**
* grant all present and future threads access to an object

8
kernel/include/syscall_handler.h
View file

@ -90,6 +90,14 @@ extern void _thread_perms_inherit(struct k_thread *parent,
*/
extern void _thread_perms_set(struct _k_object *ko, struct k_thread *thread);
/**
* Revoke a thread's permission to a kernel object
*
* @param ko Kernel object metadata to update
* @param thread The thread to grant permission
*/
extern void _thread_perms_clear(struct _k_object *ko, struct k_thread *thread);
/**
* Grant all current and future threads access to a kernel object
*

17
kernel/userspace.c
View file

@ -130,6 +130,14 @@ void _thread_perms_set(struct _k_object *ko, struct k_thread *thread)
}
}
void _thread_perms_clear(struct _k_object *ko, struct k_thread *thread)
{
if (thread->base.perm_index < 8 * CONFIG_MAX_THREAD_BYTES) {
sys_bitfield_clear_bit((mem_addr_t)&ko->perms,
thread->base.perm_index);
}
}
static int thread_perms_test(struct _k_object *ko)
{
if (_current->base.perm_index < 8 * CONFIG_MAX_THREAD_BYTES) {
@ -180,6 +188,15 @@ void _impl_k_object_access_grant(void *object, struct k_thread *thread)
}
}
void _impl_k_object_access_revoke(void *object, struct k_thread *thread)
{
struct _k_object *ko = _k_object_find(object);
if (ko) {
_thread_perms_clear(ko, thread);
}
}
void _impl_k_object_access_all_grant(void *object)
{
struct _k_object *ko = _k_object_find(object);

12
kernel/userspace_handler.c
View file

@ -47,6 +47,18 @@ _SYSCALL_HANDLER2(k_object_access_grant, object, thread)
return 0;
}
_SYSCALL_HANDLER2(k_object_access_revoke, object, thread)
{
struct _k_object *ko;
_SYSCALL_OBJ(thread, K_OBJ_THREAD);
ko = validate_any_object((void *)object);
_SYSCALL_VERIFY_MSG(ko, "object %p access denied", (void *)object);
_thread_perms_clear(ko, (struct k_thread *)thread);
return 0;
}
_SYSCALL_HANDLER1(k_object_access_all_grant, object)
{
struct _k_object *ko;