kdbus: add CMD_UPDATE_METADATA ioctl (reinitialize connection metadata)

Added to satisfy efl/launchpad developers' request.

Tizen code routinely performs the following operation sequence:
1. create kdbus connection
2. update seclabel
3. rely on updated seclabel

CONN_INFO has always returned seclabel collected at HELLO time (behavior
consistent across all kdbus versions and documented in kdbus man). This
would break step 3 of the above sequence.

KDBUS_CMD_UPDATE_METADATA ioctl updates a connection's metadata to
reflect the current state. Metadata is collected in the exact same way
as during HELLO.

Semantics Required by efl/launchpad can be obtained by altering the
sequence like so:
1. create kdbus connection
2. update seclabel
+2b. ioctl(connection_fd, KDBUS_CMD_UPDATE_METADATA);
3. rely on updated seclabel

Change-Id: I4a4b2aea4256f8bfb3bd1c0d3df5e963d243cb52
Signed-off-by: Konrad Lipinski <konrad.l@samsung.com>

6 files changed, 138 insertions, 83 deletions

diff --git a/include/uapi/linux/kdbus.h b/include/uapi/linux/kdbus.h
index 4fc44cb1d4a8..778bccb2400e 100644
--- a/include/uapi/linux/kdbus.h
+++ b/include/uapi/linux/kdbus.h
@@ -979,6 +979,9 @@ enum kdbus_ioctl_type {
 					     struct kdbus_cmd_match),
 	KDBUS_CMD_MATCH_REMOVE =	_IOW(KDBUS_IOCTL_MAGIC, 0xb1,
 					     struct kdbus_cmd_match),
+
+	/* Tizen */
+	KDBUS_CMD_UPDATE_METADATA = _IO(KDBUS_IOCTL_MAGIC, 0xd0),
 };
 
 #endif /* _UAPI_KDBUS_H_ */
diff --git a/ipc/kdbus/connection.c b/ipc/kdbus/connection.c
index 02deba366839..2f850bdb508e 100644
--- a/ipc/kdbus/connection.c
+++ b/ipc/kdbus/connection.c
@@ -57,6 +57,8 @@
  */
 #define DISABLE_KDBUS_POLICY
 
+static int kdbus_conn_meta_update(struct kdbus_conn *conn, bool first_time);
+
 static struct kdbus_conn *kdbus_conn_new(struct kdbus_ep *ep,
 					 struct file *file,
 					 struct kdbus_cmd_hello *hello,
@@ -195,25 +197,7 @@ static struct kdbus_conn *kdbus_conn_new(struct kdbus_ep *ep,
 		if (ret < 0)
 			goto exit_unref;
 	} else {
-		conn->meta_proc = kdbus_meta_proc_new();
-		if (IS_ERR(conn->meta_proc)) {
-			ret = PTR_ERR(conn->meta_proc);
-			conn->meta_proc = NULL;
-			goto exit_unref;
-		}
-
-		ret = kdbus_meta_proc_collect(conn->meta_proc,
-					      KDBUS_ATTACH_CREDS |
-					      KDBUS_ATTACH_PIDS |
-					      KDBUS_ATTACH_AUXGROUPS |
-					      KDBUS_ATTACH_TID_COMM |
-					      KDBUS_ATTACH_PID_COMM |
-					      KDBUS_ATTACH_EXE |
-					      KDBUS_ATTACH_CMDLINE |
-					      KDBUS_ATTACH_CGROUP |
-					      KDBUS_ATTACH_CAPS |
-					      KDBUS_ATTACH_SECLABEL |
-					      KDBUS_ATTACH_AUDIT);
+		ret = kdbus_conn_meta_update(conn, 1);
 		if (ret < 0)
 			goto exit_unref;
 	}
@@ -1734,6 +1718,7 @@ int kdbus_cmd_conn_info(struct kdbus_conn *conn, void __user *argp)
 	struct kdbus_name_owner *owner = NULL;
 	struct kdbus_conn *owner_conn = NULL;
 	struct kdbus_item *meta_items = NULL;
+	struct kdbus_meta_proc *meta_proc = NULL;
 	struct kdbus_info info = {};
 	struct kdbus_cmd_info *cmd;
 	struct kdbus_bus *bus = conn->ep->bus;
@@ -1805,7 +1790,13 @@ int kdbus_cmd_conn_info(struct kdbus_conn *conn, void __user *argp)
 	if (ret < 0)
 		goto exit;
 
-	ret = kdbus_meta_emit(owner_conn->meta_proc, owner_conn->meta_fake,
+	if (!owner_conn->meta_fake) {
+		rcu_read_lock();
+		meta_proc = rcu_dereference(owner_conn->meta_proc);
+		kdbus_meta_proc_ref(meta_proc);
+		rcu_read_unlock();
+	}
+	ret = kdbus_meta_emit(meta_proc, owner_conn->meta_fake,
 			      conn_meta, conn, attach_flags,
 			      &meta_items, &meta_size);
 	if (ret < 0)
@@ -1849,6 +1840,7 @@ exit:
 	kdbus_pool_slice_release(slice);
 	kfree(meta_items);
 	kdbus_meta_conn_unref(conn_meta);
+	kdbus_meta_proc_unref(meta_proc);
 	kdbus_conn_unref(owner_conn);
 	return kdbus_args_clear(&args, ret);
 }
@@ -2243,3 +2235,56 @@ int kdbus_cmd_free(struct kdbus_conn *conn, void __user *argp)
 
 	return kdbus_args_clear(&args, ret);
 }
+
+static int kdbus_conn_meta_update(struct kdbus_conn *conn, bool first_time)
+{
+	int ret;
+	struct kdbus_meta_proc *mp = kdbus_meta_proc_new();
+
+	if (IS_ERR(mp))
+		return PTR_ERR(mp);
+
+	ret = kdbus_meta_proc_collect(mp,
+					  KDBUS_ATTACH_CREDS |
+					  KDBUS_ATTACH_PIDS |
+					  KDBUS_ATTACH_AUXGROUPS |
+					  KDBUS_ATTACH_TID_COMM |
+					  KDBUS_ATTACH_PID_COMM |
+					  KDBUS_ATTACH_EXE |
+					  KDBUS_ATTACH_CMDLINE |
+					  KDBUS_ATTACH_CGROUP |
+					  KDBUS_ATTACH_CAPS |
+					  KDBUS_ATTACH_SECLABEL |
+					  KDBUS_ATTACH_AUDIT);
+	if (ret < 0) {
+		kdbus_meta_proc_free(&mp->kref);
+		return ret;
+	}
+
+	if (first_time)
+		conn->meta_proc = mp;
+	else {
+		struct kdbus_meta_proc *old_meta;
+		mutex_lock(&conn->lock);
+		old_meta = conn->meta_proc;
+		rcu_assign_pointer(conn->meta_proc, mp);
+		synchronize_rcu();
+		mutex_unlock(&conn->lock);
+		kdbus_meta_proc_unref(old_meta);
+	}
+
+	return 0;
+}
+
+/**
+ * kdbus_cmd_update_metadata() - handle KDBUS_CMD_UPDATE_METADATA
+ * @conn:              connection to operate on
+ *
+ * Return: >=0 on success, negative error code on failure.
+ */
+int kdbus_cmd_update_metadata(struct kdbus_conn *conn)
+{
+	if (conn->meta_fake)
+		return -EOPNOTSUPP;
+	return kdbus_conn_meta_update(conn, 0);
+}
diff --git a/ipc/kdbus/connection.h b/ipc/kdbus/connection.h
index 1ad082014faa..bd96a1cdb889 100644
--- a/ipc/kdbus/connection.h
+++ b/ipc/kdbus/connection.h
@@ -158,6 +158,7 @@ struct kdbus_conn *kdbus_cmd_hello(struct kdbus_ep *ep, struct file *file,
 int kdbus_cmd_byebye_unlocked(struct kdbus_conn *conn, void __user *argp);
 int kdbus_cmd_conn_info(struct kdbus_conn *conn, void __user *argp);
 int kdbus_cmd_update(struct kdbus_conn *conn, void __user *argp);
+int kdbus_cmd_update_metadata(struct kdbus_conn *conn);
 int kdbus_cmd_send(struct kdbus_conn *conn, struct file *f, void __user *argp);
 int kdbus_cmd_recv(struct kdbus_conn *conn, void __user *argp);
 int kdbus_cmd_free(struct kdbus_conn *conn, void __user *argp);
diff --git a/ipc/kdbus/handle.c b/ipc/kdbus/handle.c
index fc60932d69c7..c5ce6cf6f8fa 100644
--- a/ipc/kdbus/handle.c
+++ b/ipc/kdbus/handle.c
@@ -498,6 +498,9 @@ static long kdbus_handle_ioctl_connected(struct file *file,
 	case KDBUS_CMD_UPDATE:
 		ret = kdbus_cmd_update(conn, buf);
 		break;
+	case KDBUS_CMD_UPDATE_METADATA:
+		ret = kdbus_cmd_update_metadata(conn);
+		break;
 	case KDBUS_CMD_MATCH_ADD:
 		ret = kdbus_cmd_match_add(conn, buf);
 		break;
@@ -576,6 +579,7 @@ static long kdbus_handle_ioctl(struct file *file, unsigned int cmd,
 	case KDBUS_CMD_NAME_ACQUIRE:
 	case KDBUS_CMD_NAME_RELEASE:
 	case KDBUS_CMD_LIST:
+	case KDBUS_CMD_UPDATE_METADATA:
 	case KDBUS_CMD_CONN_INFO:
 	case KDBUS_CMD_BUS_CREATOR_INFO:
 	case KDBUS_CMD_UPDATE:
diff --git a/ipc/kdbus/metadata.c b/ipc/kdbus/metadata.c
index 106ec26f2882..e5dd313fb0cf 100644
--- a/ipc/kdbus/metadata.c
+++ b/ipc/kdbus/metadata.c
@@ -19,9 +19,7 @@
 #include <linux/file.h>
 #include <linux/fs_struct.h>
 #include <linux/init.h>
-#include <linux/kref.h>
 #include <linux/mutex.h>
-#include <linux/sched.h>
 #include <linux/security.h>
 #include <linux/sizes.h>
 #include <linux/slab.h>
@@ -39,65 +37,6 @@
 #include "names.h"
 
 /**
- * struct kdbus_meta_proc - Process metadata
- * @kref:		Reference counting
- * @lock:		Object lock
- * @collected:		Bitmask of collected items
- * @valid:		Bitmask of collected and valid items
- * @cred:		Credentials
- * @pid:		PID of process
- * @tgid:		TGID of process
- * @ppid:		PPID of process
- * @tid_comm:		TID comm line
- * @pid_comm:		PID comm line
- * @exe_path:		Executable path
- * @root_path:		Root-FS path
- * @cmdline:		Command-line
- * @cgroup:		Full cgroup path
- * @seclabel:		Seclabel
- * @audit_loginuid:	Audit login-UID
- * @audit_sessionid:	Audit session-ID
- */
-struct kdbus_meta_proc {
-	struct kref kref;
-	struct mutex lock;
-	u64 collected;
-	u64 valid;
-
-	/* KDBUS_ITEM_CREDS */
-	/* KDBUS_ITEM_AUXGROUPS */
-	/* KDBUS_ITEM_CAPS */
-	const struct cred *cred;
-
-	/* KDBUS_ITEM_PIDS */
-	struct pid *pid;
-	struct pid *tgid;
-	struct pid *ppid;
-
-	/* KDBUS_ITEM_TID_COMM */
-	char tid_comm[TASK_COMM_LEN];
-	/* KDBUS_ITEM_PID_COMM */
-	char pid_comm[TASK_COMM_LEN];
-
-	/* KDBUS_ITEM_EXE */
-	struct path exe_path;
-	struct path root_path;
-
-	/* KDBUS_ITEM_CMDLINE */
-	char *cmdline;
-
-	/* KDBUS_ITEM_CGROUP */
-	char *cgroup;
-
-	/* KDBUS_ITEM_SECLABEL */
-	char *seclabel;
-
-	/* KDBUS_ITEM_AUDIT */
-	kuid_t audit_loginuid;
-	unsigned int audit_sessionid;
-};
-
-/**
  * struct kdbus_meta_conn
  * @kref:		Reference counting
  * @lock:		Object lock
@@ -152,7 +91,7 @@ struct kdbus_meta_proc *kdbus_meta_proc_new(void)
 	return mp;
 }
 
-static void kdbus_meta_proc_free(struct kref *kref)
+void kdbus_meta_proc_free(struct kref *kref)
 {
 	struct kdbus_meta_proc *mp = container_of(kref, struct kdbus_meta_proc,
 						  kref);
diff --git a/ipc/kdbus/metadata.h b/ipc/kdbus/metadata.h
index dba7cc7fdbcb..e8d8433d4b0f 100644
--- a/ipc/kdbus/metadata.h
+++ b/ipc/kdbus/metadata.h
@@ -16,14 +16,76 @@
 #define __KDBUS_METADATA_H
 
 #include <linux/kernel.h>
+#include <linux/kref.h>
+#include <linux/path.h>
+#include <linux/sched.h>
 
 struct kdbus_conn;
 struct kdbus_pool_slice;
 
-struct kdbus_meta_proc;
 struct kdbus_meta_conn;
 
 /**
+ * struct kdbus_meta_proc - Process metadata
+ * @kref:		Reference counting
+ * @lock:		Object lock
+ * @collected:		Bitmask of collected items
+ * @valid:		Bitmask of collected and valid items
+ * @cred:		Credentials
+ * @pid:		PID of process
+ * @tgid:		TGID of process
+ * @ppid:		PPID of process
+ * @tid_comm:		TID comm line
+ * @pid_comm:		PID comm line
+ * @exe_path:		Executable path
+ * @root_path:		Root-FS path
+ * @cmdline:		Command-line
+ * @cgroup:		Full cgroup path
+ * @seclabel:		Seclabel
+ * @audit_loginuid:	Audit login-UID
+ * @audit_sessionid:	Audit session-ID
+ */
+struct kdbus_meta_proc {
+	struct kref kref;
+	struct mutex lock;
+	u64 collected;
+	u64 valid;
+
+	/* KDBUS_ITEM_CREDS */
+	/* KDBUS_ITEM_AUXGROUPS */
+	/* KDBUS_ITEM_CAPS */
+	const struct cred *cred;
+
+	/* KDBUS_ITEM_PIDS */
+	struct pid *pid;
+	struct pid *tgid;
+	struct pid *ppid;
+
+	/* KDBUS_ITEM_TID_COMM */
+	char tid_comm[TASK_COMM_LEN];
+	/* KDBUS_ITEM_PID_COMM */
+	char pid_comm[TASK_COMM_LEN];
+
+	/* KDBUS_ITEM_EXE */
+	struct path exe_path;
+	struct path root_path;
+
+	/* KDBUS_ITEM_CMDLINE */
+	char *cmdline;
+
+	/* KDBUS_ITEM_CGROUP */
+	char *cgroup;
+
+	/* KDBUS_ITEM_SECLABEL */
+	char *seclabel;
+
+	/* KDBUS_ITEM_AUDIT */
+	kuid_t audit_loginuid;
+	unsigned int audit_sessionid;
+};
+
+
+/**
  * struct kdbus_meta_fake - Fake metadata
  * @valid:		Bitmask of collected and valid items
  * @uid:		UID of process
@@ -56,6 +118,7 @@ struct kdbus_meta_fake {
 struct kdbus_meta_proc *kdbus_meta_proc_new(void);
 struct kdbus_meta_proc *kdbus_meta_proc_ref(struct kdbus_meta_proc *mp);
 struct kdbus_meta_proc *kdbus_meta_proc_unref(struct kdbus_meta_proc *mp);
+void kdbus_meta_proc_free(struct kref *mpkref);
 int kdbus_meta_proc_collect(struct kdbus_meta_proc *mp, u64 what);
 
 struct kdbus_meta_fake *kdbus_meta_fake_new(void);