Struct ThreadState

pub struct ThreadState;

Static utility functions to manage Binder thread state.

Implementations

impl ThreadState

pub fn get_calling_uid() -> uid_t

This returns the calling UID assuming that this thread is called from a thread that is processing a binder transaction (for instance, in the implementation of Remotable::on_transact).

This can be used with higher-level system services to determine the caller’s identity and check permissions.

Available since API level 29.

\return calling uid or the current process’s UID if this thread isn’t processing a transaction.

pub fn get_calling_pid() -> pid_t

This returns the calling PID assuming that this thread is called from a thread that is processing a binder transaction (for instance, in the implementation of Remotable::on_transact).

This can be used with higher-level system services to determine the caller’s identity and check permissions. However, when doing this, one should be aware of possible TOCTOU problems when the calling process dies and is replaced with another process with elevated permissions and the same PID.

Warning: oneway transactions do not receive PID. Even if you expect a transaction to be synchronous, a misbehaving client could send it as a synchronous call and result in a 0 PID here. Additionally, if there is a race and the calling process dies, the PID may still be 0 for a synchronous call.

Available since API level 29.

\return calling pid or the current process’s PID if this thread isn’t processing a transaction.

pub fn is_handling_transaction() -> bool

Determine whether the current thread is currently executing an incoming transaction.

\return true if the current thread is currently executing an incoming transaction, and false otherwise.

pub fn with_calling_sid<T, F>(check_permission: F) -> T

where for<'a> F: FnOnce(Option<&'a CStr>) -> T,

This function makes the client’s security context available to the service calling this function. This can be used for access control. It does not suffer from the TOCTOU issues of get_calling_pid.

Implementations of check_permission should use the given CStr argument as context for selinux permission checks. If None is given, the implementation should fall back to using the PID instead.

Note: None may be passed to the callback if the caller did not set_requesting_sid on the serviced binder, or if the underlying kernel is too old to support this feature.