Implemented mechanism to trigger predefined execution in dom0.

Processes in AppVM can ask qrexec-agent to send a
MSG_AGENT_TO_SERVER_TRIGGER_EXEC message to qrexec-daemon.
The latter will execute predefined program. It is useful for
the purpose of file copy; the predefined program will create
a connected qfile-daemon<->qfile-agent pair.

qrexec/qrexec.h

@@ -25,6 +25,8 @@
 
 #define REXEC_PORT 512
 
+#define QREXEC_AGENT_TRIGGER_PATH "/var/run/qubes/qrexec_agent"
+
 enum {
 	MSG_CLIENT_TO_SERVER_EXEC_CMDLINE = 0x100,
 	MSG_CLIENT_TO_SERVER_JUST_EXEC,
@@ -40,12 +42,18 @@ enum {
 	MSG_AGENT_TO_SERVER_STDOUT,
 	MSG_AGENT_TO_SERVER_STDERR,
 	MSG_AGENT_TO_SERVER_EXIT_CODE,
+	MSG_AGENT_TO_SERVER_TRIGGER_EXEC,
 
 	MSG_SERVER_TO_CLIENT_STDOUT,
 	MSG_SERVER_TO_CLIENT_STDERR,
 	MSG_SERVER_TO_CLIENT_EXIT_CODE
 };
 
+enum {
+	QREXEC_EXECUTE_FILE_COPY=0x700,
+	QREXEC_EXECUTE_FILE_COPY_FOR_DISPVM
+};
+	
 struct server_header {
 	unsigned int type;
 	unsigned int clid;

qrexec/qrexec_agent.c

@@ -30,6 +30,7 @@
 #include <string.h>
 #include <pwd.h>
 #include <grp.h>
+#include <sys/stat.h>
 #include "qrexec.h"
 #include "buffer.h"
 #include "glue.h"
@@ -63,9 +64,16 @@ struct _process_fd process_fd[MAX_FDS];
 /* indexed by client id, which is descriptor number of a client in daemon */
 struct _client_info client_info[MAX_FDS];
 
+int trigger_fd;
+
 void init()
 {
 	peer_server_init(REXEC_PORT);
+	umask(0);
+	mkfifo(QREXEC_AGENT_TRIGGER_PATH, 0666);
+	umask(077);
+	trigger_fd =
+	    open(QREXEC_AGENT_TRIGGER_PATH, O_RDONLY | O_NONBLOCK);
 }
 
 void no_colon_in_cmd()
@@ -418,6 +426,11 @@ int fill_fds_for_select(fd_set * rdset, fd_set * wrset)
 			FD_SET(i, rdset);
 			max = i;
 		}
+
+	FD_SET(trigger_fd, rdset);
+	if (trigger_fd > max)
+		max = trigger_fd;
+
 	for (i = 0; i < MAX_FDS; i++)
 		if (client_info[i].pid > 0 && client_info[i].is_blocked) {
 			fd = client_info[i].stdin_fd;
@@ -446,6 +459,28 @@ void flush_client_data_agent(int clid)
 	}
 }
 
+void handle_trigger_io()
+{
+	struct server_header s_hdr;
+	char buf[5];
+
+	s_hdr.clid = 0;
+	s_hdr.len = 0;
+	if (read(trigger_fd, buf, 4) == 4) {
+		buf[4] = 0;
+		if (!strcmp(buf, "FCPR"))
+			s_hdr.clid = QREXEC_EXECUTE_FILE_COPY;
+		else if (!strcmp(buf, "DVMR"))
+			s_hdr.clid = QREXEC_EXECUTE_FILE_COPY_FOR_DISPVM;
+		if (s_hdr.clid) {
+			s_hdr.type = MSG_AGENT_TO_SERVER_TRIGGER_EXEC;
+			write_all_vchan_ext(&s_hdr, sizeof s_hdr);
+		}
+	}
+	close(trigger_fd);
+	trigger_fd =
+	    open(QREXEC_AGENT_TRIGGER_PATH, O_RDONLY | O_NONBLOCK);
+}
 
 int main()
 {
@@ -469,6 +504,9 @@ int main()
 		while (read_ready_vchan_ext())
 			handle_server_data();
 
+		if (FD_ISSET(trigger_fd, &rdset))
+			handle_trigger_io();
+
 		handle_process_data_all(&rdset);
 		for (i = 0; i <= MAX_FDS; i++)
 			if (client_info[i].pid > 0

qrexec/qrexec_daemon.c

@@ -51,9 +51,11 @@ int server_fd;
 
 void handle_usr1(int x)
 {
-        exit(0);
+	exit(0);
 }
 
+char domain_id[64];
+
 void init(int xid)
 {
 	char dbg_log[256];
@@ -63,6 +65,7 @@ void init(int xid)
 		fprintf(stderr, "domain id=0?\n");
 		exit(1);
 	}
+	snprintf(domain_id, sizeof(domain_id), "%d", xid);
 	signal(SIGUSR1, handle_usr1);
 	switch (fork()) {
 	case -1:
@@ -71,7 +74,7 @@ void init(int xid)
 	case 0:
 		break;
 	default:
-	        pause();
+		pause();
 		exit(0);
 	}
 	close(0);
@@ -94,6 +97,7 @@ void init(int xid)
 	peer_client_init(xid, REXEC_PORT);
 	setuid(getuid());
 	signal(SIGPIPE, SIG_IGN);
+	signal(SIGCHLD, SIG_IGN);
 	signal(SIGUSR1, SIG_DFL);
 	kill(getppid(), SIGUSR1);
 }
@@ -242,6 +246,41 @@ void pass_to_client(int clid, struct client_header *hdr)
 	}
 }
 
+void handle_trigger_exec(int req)
+{
+	char *rcmd = NULL, *lcmd = NULL;
+	int i;
+	switch (req) {
+	case QREXEC_EXECUTE_FILE_COPY:
+		rcmd = "directly:user:/usr/lib/qubes/qfile-agent";
+		lcmd = "/usr/lib/qubes/qfile-daemon";
+		break;
+	case QREXEC_EXECUTE_FILE_COPY_FOR_DISPVM:
+		rcmd = "directly:user:/usr/lib/qubes/qfile-agent-dvm";
+		lcmd = "/usr/lib/qubes/qfile-daemon-dvm";
+		break;
+	default:
+		fprintf(stderr, "got trigger exec no %d\n", req);
+		exit(1);
+	}
+	switch (fork()) {
+	case -1:
+		perror("fork");
+		exit(1);
+	case 0:
+		break;
+	default:
+		return;
+	}
+	for (i = 3; i < 256; i++)
+		close(i);
+	signal(SIGCHLD, SIG_DFL);
+	execl("/usr/lib/qubes/qrexec_client", "qrexec_client", "-d",
+	      domain_id, "-l", lcmd, rcmd, NULL);
+	perror("execl");
+	exit(1);
+}
+
 void handle_agent_data()
 {
 	struct client_header hdr;
@@ -251,6 +290,11 @@ void handle_agent_data()
 //      fprintf(stderr, "got %x %x %x\n", s_hdr.type, s_hdr.clid,
 //              s_hdr.len);
 
+	if (s_hdr.type == MSG_AGENT_TO_SERVER_TRIGGER_EXEC) {
+		handle_trigger_exec(s_hdr.clid);
+		return;
+	}
+
 	if (s_hdr.clid >= MAX_FDS || s_hdr.clid < 0) {
 		fprintf(stderr, "from agent: clid=%d\n", s_hdr.clid);
 		exit(1);

rpm_spec/core-appvm.spec

@@ -107,6 +107,7 @@ install -D ../u2mfn/u2mfn-kernel.h $RPM_BUILD_ROOT/usr/include/u2mfn-kernel.h
 install -D ../vchan/libvchan.so $RPM_BUILD_ROOT/%{_libdir}/libvchan.so
 install -D ../u2mfn/libu2mfn.so $RPM_BUILD_ROOT/%{_libdir}/libu2mfn.so
 
+mkdir -p $RPM_BUILD_ROOT/var/run/qubes
 
 %triggerin -- initscripts
 cp /var/lib/qubes/serial.conf /etc/init/serial.conf
@@ -227,6 +228,7 @@ rm -rf $RPM_BUILD_ROOT
 /usr/include/libvchan.h
 %{_libdir}/libvchan.so
 %{_libdir}/libu2mfn.so
+%dir /var/run/qubes
 
 
 %package devel

rpm_spec/core-netvm.spec

@@ -83,6 +83,7 @@ cp ../common/vif-route-qubes $RPM_BUILD_ROOT/etc/xen/scripts
 install -D ../vchan/libvchan.so $RPM_BUILD_ROOT/%{_libdir}/libvchan.so
 install -D ../u2mfn/libu2mfn.so $RPM_BUILD_ROOT/%{_libdir}/libu2mfn.so
 
+mkdir -p $RPM_BUILD_ROOT/var/run/qubes
 
 %triggerin -- initscripts
 cp /var/lib/qubes/serial.conf /etc/init/serial.conf
@@ -193,3 +194,4 @@ rm -rf $RPM_BUILD_ROOT
 %dir /var/run/qubes
 %{_libdir}/libvchan.so
 %{_libdir}/libu2mfn.so
+%dir /var/run/qubes