binder: make FIFO inheritance a per-context option
Add a new ioctl to binder to control whether FIFO inheritance should happen.
In particular, hwbinder should inherit FIFO priority from callers, but standard
binder threads should not.
Test: boots
bug 36516194
Signed-off-by: Tim Murray <timmurray@google.com>
Change-Id: I8100c4364b7d15d1bf00a8ca5c286e4d4b23ce85
diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c
index 08752e0..d14584df 100644
--- a/drivers/staging/android/binder.c
+++ b/drivers/staging/android/binder.c
@@ -243,6 +243,7 @@
struct binder_node *binder_context_mgr_node;
kuid_t binder_context_mgr_uid;
const char *name;
+ bool inherit_fifo_prio;
};
struct binder_device {
@@ -623,11 +624,12 @@
struct binder_transaction *t, struct binder_node *target_node)
{
bool oneway = !!(t->flags & TF_ONE_WAY);
+ bool inherit_fifo = target_node->proc->context->inherit_fifo_prio;
t->saved_sched_policy = current->policy;
t->saved_priority = task_nice(current);
- if (!oneway && is_rt_policy(t->sched_policy) &&
+ if (!oneway && inherit_fifo && is_rt_policy(t->sched_policy) &&
!is_rt_policy(current->policy)) {
/* Transaction was initiated with a real-time policy,
* but we are not; temporarily upgrade this thread to RT.
@@ -3615,6 +3617,34 @@
return ret;
}
+static int binder_ioctl_set_inherit_fifo_prio(struct file *filp)
+{
+ int ret = 0;
+ struct binder_proc *proc = filp->private_data;
+ struct binder_context *context = proc->context;
+
+ kuid_t curr_euid = current_euid();
+ mutex_lock(&binder_context_mgr_node_lock);
+
+ if (uid_valid(context->binder_context_mgr_uid)) {
+ if (!uid_eq(context->binder_context_mgr_uid, curr_euid)) {
+ pr_err("BINDER_SET_INHERIT_FIFO_PRIO bad uid %d != %d\n",
+ from_kuid(&init_user_ns, curr_euid),
+ from_kuid(&init_user_ns,
+ context->binder_context_mgr_uid));
+ ret = -EPERM;
+ goto out;
+ }
+ }
+
+ context->inherit_fifo_prio = true;
+
+ out:
+ mutex_unlock(&binder_context_mgr_node_lock);
+ return ret;
+}
+
+
static int binder_ioctl_set_ctx_mgr(struct file *filp)
{
int ret = 0;
@@ -3729,6 +3759,12 @@
if (ret)
goto err;
break;
+ case BINDER_SET_INHERIT_FIFO_PRIO:
+ ret = binder_ioctl_set_inherit_fifo_prio(filp);
+ if (ret)
+ goto err;
+ break;
+
case BINDER_THREAD_EXIT:
binder_debug(BINDER_DEBUG_THREADS, "%d:%d exit\n",
proc->pid, thread->pid);
@@ -4635,6 +4671,7 @@
seq_printf(m, "proc %d%s\n", proc->pid,
proc->is_zombie ? " (ZOMBIE)" : "");
seq_printf(m, "context %s\n", proc->context->name);
+ seq_printf(m, "context FIFO: %d\n", proc->context->inherit_fifo_prio);
seq_printf(m, " cleared: procs=%d nodes=%d threads=%d\n",
cleared_procs, cleared_nodes, cleared_threads);
zombie_threads = zombie_nodes = zombie_refs = count = 0;
diff --git a/drivers/staging/android/uapi/binder.h b/drivers/staging/android/uapi/binder.h
index 4212aff..2c67b87 100644
--- a/drivers/staging/android/uapi/binder.h
+++ b/drivers/staging/android/uapi/binder.h
@@ -190,6 +190,7 @@
#define BINDER_SET_CONTEXT_MGR _IOW('b', 7, __s32)
#define BINDER_THREAD_EXIT _IOW('b', 8, __s32)
#define BINDER_VERSION _IOWR('b', 9, struct binder_version)
+#define BINDER_SET_INHERIT_FIFO_PRIO _IO('b', 10)
/*
* NOTE: Two special error codes you should check for when calling
