binder: Support multiple context managers

Move the context manager state into a separate
struct context, and allow for each process to have
its own context associated with it.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Martijn Coenen <maco@google.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Amit Pundir <amit.pundir@linaro.org>
Cc: Serban Constantinescu <serban.constantinescu@arm.com>
Cc: Dmitry Shmidt <dimitrysh@google.com>
Cc: Rom Lemarchand <romlem@google.com>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Martijn Coenen <maco@google.com>
[jstultz: Minor checkpatch fix]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/android/binder.c

@@ -56,8 +56,6 @@ static HLIST_HEAD(binder_dead_nodes);
 
 static struct dentry *binder_debugfs_dir_entry_root;
 static struct dentry *binder_debugfs_dir_entry_proc;
-static struct binder_node *binder_context_mgr_node;
-static kuid_t binder_context_mgr_uid = INVALID_UID;
 static int binder_last_id;
 
 #define BINDER_DEBUG_ENTRY(name) \
@@ -215,6 +213,15 @@ static struct binder_transaction_log_entry *binder_transaction_log_add(
 	return e;
 }
 
+struct binder_context {
+	struct binder_node *binder_context_mgr_node;
+	kuid_t binder_context_mgr_uid;
+};
+
+static struct binder_context global_context = {
+	.binder_context_mgr_uid = INVALID_UID,
+};
+
 struct binder_work {
 	struct list_head entry;
 	enum {
@@ -330,6 +337,7 @@ struct binder_proc {
 	int ready_threads;
 	long default_priority;
 	struct dentry *debugfs_entry;
+	struct binder_context *context;
 };
 
 enum {
@@ -934,7 +942,8 @@ static int binder_inc_node(struct binder_node *node, int strong, int internal,
 		if (internal) {
 			if (target_list == NULL &&
 			    node->internal_strong_refs == 0 &&
-			    !(node == binder_context_mgr_node &&
+			    !(node->proc &&
+			      node == node->proc->context->binder_context_mgr_node &&
 			      node->has_strong_ref)) {
 				pr_err("invalid inc strong node for %d\n",
 					node->debug_id);
@@ -1036,6 +1045,7 @@ static struct binder_ref *binder_get_ref_for_node(struct binder_proc *proc,
 	struct rb_node **p = &proc->refs_by_node.rb_node;
 	struct rb_node *parent = NULL;
 	struct binder_ref *ref, *new_ref;
+	struct binder_context *context = proc->context;
 
 	while (*p) {
 		parent = *p;
@@ -1058,7 +1068,7 @@ static struct binder_ref *binder_get_ref_for_node(struct binder_proc *proc,
 	rb_link_node(&new_ref->rb_node_node, parent, p);
 	rb_insert_color(&new_ref->rb_node_node, &proc->refs_by_node);
 
-	new_ref->desc = (node == binder_context_mgr_node) ? 0 : 1;
+	new_ref->desc = (node == context->binder_context_mgr_node) ? 0 : 1;
 	for (n = rb_first(&proc->refs_by_desc); n != NULL; n = rb_next(n)) {
 		ref = rb_entry(n, struct binder_ref, rb_node_desc);
 		if (ref->desc > new_ref->desc)
@@ -1388,6 +1398,7 @@ static void binder_transaction(struct binder_proc *proc,
 	struct binder_transaction *in_reply_to = NULL;
 	struct binder_transaction_log_entry *e;
 	uint32_t return_error;
+	struct binder_context *context = proc->context;
 
 	e = binder_transaction_log_add(&binder_transaction_log);
 	e->call_type = reply ? 2 : !!(tr->flags & TF_ONE_WAY);
@@ -1448,7 +1459,7 @@ static void binder_transaction(struct binder_proc *proc,
 			}
 			target_node = ref->node;
 		} else {
-			target_node = binder_context_mgr_node;
+			target_node = context->binder_context_mgr_node;
 			if (target_node == NULL) {
 				return_error = BR_DEAD_REPLY;
 				goto err_no_context_mgr_node;
@@ -1839,6 +1850,7 @@ static int binder_thread_write(struct binder_proc *proc,
 			binder_size_t *consumed)
 {
 	uint32_t cmd;
+	struct binder_context *context = proc->context;
 	void __user *buffer = (void __user *)(uintptr_t)binder_buffer;
 	void __user *ptr = buffer + *consumed;
 	void __user *end = buffer + size;
@@ -1865,10 +1877,10 @@ static int binder_thread_write(struct binder_proc *proc,
 			if (get_user(target, (uint32_t __user *)ptr))
 				return -EFAULT;
 			ptr += sizeof(uint32_t);
-			if (target == 0 && binder_context_mgr_node &&
+			if (target == 0 && context->binder_context_mgr_node &&
 			    (cmd == BC_INCREFS || cmd == BC_ACQUIRE)) {
 				ref = binder_get_ref_for_node(proc,
-					       binder_context_mgr_node);
+					context->binder_context_mgr_node);
 				if (ref->desc != target) {
 					binder_user_error("%d:%d tried to acquire reference to desc 0, got %d instead\n",
 						proc->pid, thread->pid,
@@ -2774,9 +2786,11 @@ static int binder_ioctl_set_ctx_mgr(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();
 
-	if (binder_context_mgr_node != NULL) {
+	if (context->binder_context_mgr_node) {
 		pr_err("BINDER_SET_CONTEXT_MGR already set\n");
 		ret = -EBUSY;
 		goto out;
@@ -2784,27 +2798,27 @@ static int binder_ioctl_set_ctx_mgr(struct file *filp)
 	ret = security_binder_set_context_mgr(proc->tsk);
 	if (ret < 0)
 		goto out;
-	if (uid_valid(binder_context_mgr_uid)) {
-		if (!uid_eq(binder_context_mgr_uid, curr_euid)) {
+	if (uid_valid(context->binder_context_mgr_uid)) {
+		if (!uid_eq(context->binder_context_mgr_uid, curr_euid)) {
 			pr_err("BINDER_SET_CONTEXT_MGR bad uid %d != %d\n",
 			       from_kuid(&init_user_ns, curr_euid),
 			       from_kuid(&init_user_ns,
-					binder_context_mgr_uid));
+					 context->binder_context_mgr_uid));
 			ret = -EPERM;
 			goto out;
 		}
 	} else {
-		binder_context_mgr_uid = curr_euid;
+		context->binder_context_mgr_uid = curr_euid;
 	}
-	binder_context_mgr_node = binder_new_node(proc, 0, 0);
-	if (binder_context_mgr_node == NULL) {
+	context->binder_context_mgr_node = binder_new_node(proc, 0, 0);
+	if (!context->binder_context_mgr_node) {
 		ret = -ENOMEM;
 		goto out;
 	}
-	binder_context_mgr_node->local_weak_refs++;
-	binder_context_mgr_node->local_strong_refs++;
-	binder_context_mgr_node->has_strong_ref = 1;
-	binder_context_mgr_node->has_weak_ref = 1;
+	context->binder_context_mgr_node->local_weak_refs++;
+	context->binder_context_mgr_node->local_strong_refs++;
+	context->binder_context_mgr_node->has_strong_ref = 1;
+	context->binder_context_mgr_node->has_weak_ref = 1;
 out:
 	return ret;
 }
@@ -3039,6 +3053,7 @@ static int binder_open(struct inode *nodp, struct file *filp)
 	get_task_struct(current);
 	proc->tsk = current;
 	proc->vma_vm_mm = current->mm;
+	proc->context = &global_context;
 	INIT_LIST_HEAD(&proc->todo);
 	init_waitqueue_head(&proc->wait);
 	proc->default_priority = task_nice(current);
@@ -3151,6 +3166,7 @@ static int binder_node_release(struct binder_node *node, int refs)
 static void binder_deferred_release(struct binder_proc *proc)
 {
 	struct binder_transaction *t;
+	struct binder_context *context = proc->context;
 	struct rb_node *n;
 	int threads, nodes, incoming_refs, outgoing_refs, buffers,
 		active_transactions, page_count;
@@ -3160,11 +3176,12 @@ static void binder_deferred_release(struct binder_proc *proc)
 
 	hlist_del(&proc->proc_node);
 
-	if (binder_context_mgr_node && binder_context_mgr_node->proc == proc) {
+	if (context->binder_context_mgr_node &&
+	    context->binder_context_mgr_node->proc == proc) {
 		binder_debug(BINDER_DEBUG_DEAD_BINDER,
 			     "%s: %d context_mgr_node gone\n",
 			     __func__, proc->pid);
-		binder_context_mgr_node = NULL;
+		context->binder_context_mgr_node = NULL;
 	}
 
 	threads = 0;