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// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2025 Google LLC.
use kernel::{
error::Error,
list::{List, ListArc, ListLinks},
prelude::*,
security,
str::{CStr, CString},
sync::{Arc, Mutex},
task::Kuid,
};
use crate::{error::BinderError, node::NodeRef, process::Process};
kernel::sync::global_lock! {
// SAFETY: We call `init` in the module initializer, so it's initialized before first use.
pub(crate) unsafe(uninit) static CONTEXTS: Mutex<ContextList> = ContextList {
list: List::new(),
};
}
pub(crate) struct ContextList {
list: List<Context>,
}
pub(crate) fn get_all_contexts() -> Result<KVec<Arc<Context>>> {
let lock = CONTEXTS.lock();
let count = lock.list.iter().count();
let mut ctxs = KVec::with_capacity(count, GFP_KERNEL)?;
for ctx in &lock.list {
ctxs.push(Arc::from(ctx), GFP_KERNEL)?;
}
Ok(ctxs)
}
/// This struct keeps track of the processes using this context, and which process is the context
/// manager.
struct Manager {
node: Option<NodeRef>,
uid: Option<Kuid>,
all_procs: List<Process>,
}
/// There is one context per binder file (/dev/binder, /dev/hwbinder, etc)
#[pin_data]
pub(crate) struct Context {
#[pin]
manager: Mutex<Manager>,
pub(crate) name: CString,
#[pin]
links: ListLinks,
}
kernel::list::impl_list_arc_safe! {
impl ListArcSafe<0> for Context { untracked; }
}
kernel::list::impl_list_item! {
impl ListItem<0> for Context {
using ListLinks { self.links };
}
}
impl Context {
pub(crate) fn new(name: &CStr) -> Result<Arc<Self>> {
let name = CString::try_from(name)?;
let list_ctx = ListArc::pin_init::<Error>(
try_pin_init!(Context {
name,
links <- ListLinks::new(),
manager <- kernel::new_mutex!(Manager {
all_procs: List::new(),
node: None,
uid: None,
}, "Context::manager"),
}),
GFP_KERNEL,
)?;
let ctx = list_ctx.clone_arc();
CONTEXTS.lock().list.push_back(list_ctx);
Ok(ctx)
}
/// Called when the file for this context is unlinked.
///
/// No-op if called twice.
pub(crate) fn deregister(&self) {
// SAFETY: We never add the context to any other linked list than this one, so it is either
// in this list, or not in any list.
unsafe { CONTEXTS.lock().list.remove(self) };
}
pub(crate) fn register_process(self: &Arc<Self>, proc: ListArc<Process>) {
if !Arc::ptr_eq(self, &proc.ctx) {
pr_err!("Context::register_process called on the wrong context.");
return;
}
self.manager.lock().all_procs.push_back(proc);
}
pub(crate) fn deregister_process(self: &Arc<Self>, proc: &Process) {
if !Arc::ptr_eq(self, &proc.ctx) {
pr_err!("Context::deregister_process called on the wrong context.");
return;
}
// SAFETY: We just checked that this is the right list.
unsafe { self.manager.lock().all_procs.remove(proc) };
}
pub(crate) fn set_manager_node(&self, node_ref: NodeRef) -> Result {
let mut manager = self.manager.lock();
if manager.node.is_some() {
pr_warn!("BINDER_SET_CONTEXT_MGR already set");
return Err(EBUSY);
}
security::binder_set_context_mgr(&node_ref.node.owner.cred)?;
// If the context manager has been set before, ensure that we use the same euid.
let caller_uid = Kuid::current_euid();
if let Some(ref uid) = manager.uid {
if *uid != caller_uid {
return Err(EPERM);
}
}
manager.node = Some(node_ref);
manager.uid = Some(caller_uid);
Ok(())
}
pub(crate) fn unset_manager_node(&self) {
let node_ref = self.manager.lock().node.take();
drop(node_ref);
}
pub(crate) fn get_manager_node(&self, strong: bool) -> Result<NodeRef, BinderError> {
self.manager
.lock()
.node
.as_ref()
.ok_or_else(BinderError::new_dead)?
.clone(strong)
.map_err(BinderError::from)
}
pub(crate) fn for_each_proc<F>(&self, mut func: F)
where
F: FnMut(&Process),
{
let lock = self.manager.lock();
for proc in &lock.all_procs {
func(&proc);
}
}
pub(crate) fn get_all_procs(&self) -> Result<KVec<Arc<Process>>> {
let lock = self.manager.lock();
let count = lock.all_procs.iter().count();
let mut procs = KVec::with_capacity(count, GFP_KERNEL)?;
for proc in &lock.all_procs {
procs.push(Arc::from(proc), GFP_KERNEL)?;
}
Ok(procs)
}
pub(crate) fn get_procs_with_pid(&self, pid: i32) -> Result<KVec<Arc<Process>>> {
let orig = self.get_all_procs()?;
let mut backing = KVec::with_capacity(orig.len(), GFP_KERNEL)?;
for proc in orig.into_iter().filter(|proc| proc.task.pid() == pid) {
backing.push(proc, GFP_KERNEL)?;
}
Ok(backing)
}
}
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