sd-bus: update to current kernel version, by splitting off the extended KDBUS_ITEM_PIDS structure from KDBUS_ITEM_CREDS

Also:

- adds support for euid, suid, fsuid, egid, sgid, fsgid fields.

- makes augmentation of creds with data from /proc explicitly
  controllable to give apps better control over this, given that this is
  racy.

- enables augmentation for kdbus connections (previously we only did it
  for dbus1). This is useful since with recent kdbus versions it is
  possible for clients to control the metadata they want to send.

- changes sd_bus_query_sender_privilege() to take the euid of the client
  into consideration, if known

- when we don't have permissions to read augmentation data from /proc,
  don't fail, just don't add the data in

1 files changed, 73 insertions, 30 deletions

diff --git a/src/libsystemd/sd-bus/kdbus.h b/src/libsystemd/sd-bus/kdbus.h
index e3a80c352d..65266ee212 100644
--- a/src/libsystemd/sd-bus/kdbus.h
+++ b/src/libsystemd/sd-bus/kdbus.h
@@ -58,22 +58,43 @@ struct kdbus_notify_name_change {
 /**
  * struct kdbus_creds - process credentials
  * @uid:		User ID
+ * @euid:		Effective UID
+ * @suid:		Saved UID
+ * @fsuid:		Filesystem UID
  * @gid:		Group ID
- * @pid:		Process ID
- * @tid:		Thread ID
- * @starttime:		Starttime of the process
- *
- * The starttime of the process PID. This is useful to detect PID overruns
- * from the client side. i.e. if you use the PID to look something up in
- * /proc/$PID/ you can afterwards check the starttime field of it, to ensure
- * you didn't run into a PID overrun.
+ * @egid:		Effective GID
+ * @sgid:		Saved GID
+ * @fsgid:		Filesystem GID
  *
  * Attached to:
  *   KDBUS_ITEM_CREDS
  */
 struct kdbus_creds {
 	__u64 uid;
+        __u64 euid;
+        __u64 suid;
+        __u64 fsuid;
 	__u64 gid;
+        __u64 egid;
+        __u64 sgid;
+        __u64 fsgid;
+};
+
+/**
+ * struct kdbus_pids - process identifiers
+ * @pid:		Process ID
+ * @tid:		Thread ID
+ * @starttime:		Starttime of the process
+ *
+ * The PID, TID and starttime of a process. The start tmie is useful to detect
+ * PID overruns from the client side. i.e. if you use the PID to look something
+ * up in /proc/$PID/ you can afterwards check the starttime field of it, to
+ * ensure you didn't run into a PID overrun.
+ *
+ * Attached to:
+ *   KDBUS_ITEM_PIDS
+ */
+struct kdbus_pids {
 	__u64 pid;
 	__u64 tid;
 	__u64 starttime;
@@ -229,14 +250,19 @@ struct kdbus_policy_access {
  * @KDBUS_ITEM_NAME:			Well-know name with flags
  * @_KDBUS_ITEM_ATTACH_BASE:		Start of metadata attach items
  * @KDBUS_ITEM_TIMESTAMP:		Timestamp
- * @KDBUS_ITEM_CREDS:			Process credential
+ * @KDBUS_ITEM_CREDS:			Process credentials
+ * @KDBUS_ITEM_PIDS:			Process identifiers
  * @KDBUS_ITEM_AUXGROUPS:		Auxiliary process groups
  * @KDBUS_ITEM_OWNED_NAME:		A name owned by the associated
  *					connection
  * @KDBUS_ITEM_TID_COMM:		Thread ID "comm" identifier
+ *					(Don't trust this, see below.)
  * @KDBUS_ITEM_PID_COMM:		Process ID "comm" identifier
+ *					(Don't trust this, see below.)
  * @KDBUS_ITEM_EXE:			The path of the executable
+ *					(Don't trust this, see below.)
  * @KDBUS_ITEM_CMDLINE:			The process command line
+ *					(Don't trust this, see below.)
  * @KDBUS_ITEM_CGROUP:			The croup membership
  * @KDBUS_ITEM_CAPS:			The process capabilities
  * @KDBUS_ITEM_SECLABEL:		The security label
@@ -253,6 +279,12 @@ struct kdbus_policy_access {
  * @KDBUS_ITEM_ID_REMOVE:		Notification in kdbus_notify_id_change
  * @KDBUS_ITEM_REPLY_TIMEOUT:		Timeout has been reached
  * @KDBUS_ITEM_REPLY_DEAD:		Destination died
+ *
+ * N.B: The process and thread COMM fields, as well as the CMDLINE and
+ * EXE fields may be altered by unprivileged processes und should
+ * hence *not* used for security decisions. Peers should make use of
+ * these items only for informational purposes, such as generating log
+ * records.
  */
 enum kdbus_item_type {
 	_KDBUS_ITEM_NULL,
@@ -275,6 +307,7 @@ enum kdbus_item_type {
 	_KDBUS_ITEM_ATTACH_BASE	= 0x1000,
 	KDBUS_ITEM_TIMESTAMP	= _KDBUS_ITEM_ATTACH_BASE,
 	KDBUS_ITEM_CREDS,
+        KDBUS_ITEM_PIDS,
 	KDBUS_ITEM_AUXGROUPS,
 	KDBUS_ITEM_OWNED_NAME,
 	KDBUS_ITEM_TID_COMM,
@@ -336,6 +369,7 @@ struct kdbus_item {
 		__u64 id;
 		struct kdbus_vec vec;
 		struct kdbus_creds creds;
+                struct kdbus_pids pids;
 		struct kdbus_audit audit;
 		struct kdbus_caps caps;
 		struct kdbus_timestamp timestamp;
@@ -455,6 +489,10 @@ enum kdbus_recv_flags {
  * @offset:		Returned offset in the pool where the message is
  *			stored. The user must use KDBUS_CMD_FREE to free
  *			the allocated memory.
+ * @dropped_msgs:	In case the KDBUS_CMD_MSG_RECV ioctl returns
+ *			-EOVERFLOW, this field will contain the number of
+ *			broadcast messages that have been lost since the
+ *			last call.
  *
  * This struct is used with the KDBUS_CMD_MSG_RECV ioctl.
  */
@@ -462,7 +500,10 @@ struct kdbus_cmd_recv {
 	__u64 flags;
 	__u64 kernel_flags;
 	__s64 priority;
-	__u64 offset;
+        union {
+                __u64 offset;
+                __u64 dropped_msgs;
+        };
 } __attribute__((aligned(8)));
 
 /**
@@ -547,6 +588,7 @@ enum kdbus_hello_flags {
  * enum kdbus_attach_flags - flags for metadata attachments
  * @KDBUS_ATTACH_TIMESTAMP:		Timestamp
  * @KDBUS_ATTACH_CREDS:			Credentials
+ * @KDBUS_ATTACH_PIDS:			PIDs
  * @KDBUS_ATTACH_AUXGROUPS:		Auxiliary groups
  * @KDBUS_ATTACH_NAMES:			Well-known names
  * @KDBUS_ATTACH_TID_COMM:		The "comm" process identifier of the TID
@@ -565,18 +607,19 @@ enum kdbus_hello_flags {
 enum kdbus_attach_flags {
 	KDBUS_ATTACH_TIMESTAMP		=  1ULL <<  0,
 	KDBUS_ATTACH_CREDS		=  1ULL <<  1,
-	KDBUS_ATTACH_AUXGROUPS		=  1ULL <<  2,
-	KDBUS_ATTACH_NAMES		=  1ULL <<  3,
-	KDBUS_ATTACH_TID_COMM		=  1ULL <<  4,
-	KDBUS_ATTACH_PID_COMM		=  1ULL <<  5,
-	KDBUS_ATTACH_EXE		=  1ULL <<  6,
-	KDBUS_ATTACH_CMDLINE		=  1ULL <<  7,
-	KDBUS_ATTACH_CGROUP		=  1ULL <<  8,
-	KDBUS_ATTACH_CAPS		=  1ULL <<  9,
-	KDBUS_ATTACH_SECLABEL		=  1ULL << 10,
-	KDBUS_ATTACH_AUDIT		=  1ULL << 11,
-	KDBUS_ATTACH_CONN_DESCRIPTION	=  1ULL << 12,
-	_KDBUS_ATTACH_ALL		=  (1ULL << 13) - 1,
+        KDBUS_ATTACH_PIDS		=  1ULL <<  2,
+        KDBUS_ATTACH_AUXGROUPS		=  1ULL <<  3,
+        KDBUS_ATTACH_NAMES		=  1ULL <<  4,
+        KDBUS_ATTACH_TID_COMM		=  1ULL <<  5,
+        KDBUS_ATTACH_PID_COMM		=  1ULL <<  6,
+        KDBUS_ATTACH_EXE		=  1ULL <<  7,
+        KDBUS_ATTACH_CMDLINE		=  1ULL <<  8,
+        KDBUS_ATTACH_CGROUP		=  1ULL <<  9,
+        KDBUS_ATTACH_CAPS		=  1ULL << 10,
+        KDBUS_ATTACH_SECLABEL		=  1ULL << 11,
+        KDBUS_ATTACH_AUDIT		=  1ULL << 12,
+        KDBUS_ATTACH_CONN_DESCRIPTION	=  1ULL << 13,
+        _KDBUS_ATTACH_ALL		=  (1ULL << 14) - 1,
 	_KDBUS_ATTACH_ANY		=  ~0ULL
 };
 
@@ -619,8 +662,8 @@ struct kdbus_cmd_hello {
 
 /**
  * enum kdbus_make_flags - Flags for KDBUS_CMD_{BUS,EP,NS}_MAKE
- * @KDBUS_MAKE_ACCESS_GROUP:	Make the device node group-accessible
- * @KDBUS_MAKE_ACCESS_WORLD:	Make the device node world-accessible
+ * @KDBUS_MAKE_ACCESS_GROUP:	Make the bus or endpoint node group-accessible
+ * @KDBUS_MAKE_ACCESS_WORLD:	Make the bus or endpoint node world-accessible
  */
 enum kdbus_make_flags {
 	KDBUS_MAKE_ACCESS_GROUP		= 1ULL <<  0,
@@ -713,7 +756,7 @@ enum kdbus_name_list_flags {
 /**
  * struct kdbus_cmd_name_list - request a list of name entries
  * @flags:		Flags for the query (KDBUS_NAME_LIST_*),
- * 			userspace → kernel
+ *			userspace → kernel
  * @kernel_flags:	Supported flags for queries, kernel → userspace
  * @offset:		The returned offset in the caller's pool buffer.
  *			The user must use KDBUS_CMD_FREE to free the
@@ -834,16 +877,16 @@ struct kdbus_cmd_match {
 
 /**
  * Ioctl API
- * KDBUS_CMD_BUS_MAKE:		After opening the "control" device node, this
- *				command creates a new bus with the specified
+ * KDBUS_CMD_BUS_MAKE:		After opening the "control" node, this command
+ *				creates a new bus with the specified
  *				name. The bus is immediately shut down and
- *				cleaned up when the opened "control" device node
- *				is closed.
+ *				cleaned up when the opened file descriptor is
+ *				closed.
  * KDBUS_CMD_ENDPOINT_MAKE:	Creates a new named special endpoint to talk to
  *				the bus. Such endpoints usually carry a more
  *				restrictive policy and grant restricted access
  *				to specific applications.
- * KDBUS_CMD_HELLO:		By opening the bus device node a connection is
+ * KDBUS_CMD_HELLO:		By opening the bus node, a connection is
  *				created. After a HELLO the opened connection
  *				becomes an active peer on the bus.
  * KDBUS_CMD_BYEBYE:		Disconnect a connection. If there are no