Add kdmtsak program

Fix possible kompmgr segfault under rare circumstances


git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/kdebase@1253695 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

kdmlib/CMakeLists.txt

@@ -12,6 +12,7 @@
 include_directories(
   ${CMAKE_CURRENT_BINARY_DIR}
   ${CMAKE_SOURCE_DIR}/kdm/kfrontend
+  ${CMAKE_BINARY_DIR}
   ${TDE_INCLUDE_DIR}
   ${TQT_INCLUDE_DIRS}
 )
@@ -69,3 +70,12 @@ if( BUILD_KICKER OR BUILD_KDESKTOP OR BUILD_KDM OR BUILD_KSMSERVER )
   )
 
 endif( )
+
+##### kompmgr (executable) #######################
+
+tde_add_executable( kdmtsak
+  SOURCES kdmtsak.cpp
+  LINK ${TQT_LIBRARIES}
+  DESTINATION ${BIN_INSTALL_DIR}
+  SETUID
+)

kdmlib/kdmtsak.cpp

@@ -0,0 +1,89 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <dirent.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/select.h>
+#include <sys/time.h>
+#include <termios.h>
+#include <signal.h>
+
+#include <tqstring.h>
+
+#include "config.h"
+
+#define FIFO_FILE "/tmp/ksocket-global/tsak"
+
+// #define DEBUG
+
+int main (int argc, char *argv[])
+{
+	int mPipe_fd;
+	char readbuf[128];
+	int numread;
+
+	pid_t parentproc = getppid();
+#ifdef DEBUG
+	printf("Parent pid is: %d\n\r", parentproc);
+#endif
+
+	char parentexecutable[8192];
+	TQString procparent = TQString("/proc/%1/exe").arg(parentproc);
+	int chars = readlink(procparent.ascii(), parentexecutable, sizeof(parentexecutable));
+	parentexecutable[chars] = 0;
+	parentexecutable[8191] = 0;
+	procparent = parentexecutable;
+#ifdef DEBUG
+	printf("Parent executable name and full path is: %s\n\r", procparent.ascii());
+#endif
+
+	TQString tdeBinaryPath = TQString(KDE_BINDIR "/");
+#ifdef DEBUG
+	printf("The TDE binary path is: %s\n\r", tdeBinaryPath.ascii());
+#endif
+
+	if (!procparent.startsWith(tdeBinaryPath)) {
+		printf("Unauthorized path detected in calling process\n\r");
+		return 2;
+	}
+	else {
+		procparent = procparent.mid(tdeBinaryPath.length());
+#ifdef DEBUG
+		printf("Parent executable name is: %s\n\r", procparent.ascii());
+#endif
+		if ((procparent == "ksmserver") || (procparent == "kdesktop_lock") || (procparent == "kdm")) {
+			// OK, the calling process is authorized to retrieve SAK data
+			// First, flush the buffer
+			mPipe_fd = open(FIFO_FILE, O_RDWR | O_NONBLOCK);
+			numread = 1;
+			while (numread > 0) {
+				numread = read(mPipe_fd, readbuf, 128);
+			}
+			// Now wait for SAK press
+			mPipe_fd = open(FIFO_FILE, O_RDWR);
+			if (mPipe_fd > -1) {
+				numread = read(mPipe_fd, readbuf, 128);
+				readbuf[numread] = 0;
+				readbuf[127] = 0;
+				close(mPipe_fd);
+				if (strcmp(readbuf, "SAK\n\r") == 0) {
+					return 0;
+				}
+				else {
+					return 1;
+				}
+			}
+		}
+		else {
+			printf("Unauthorized calling process detected\n\r");
+			return 3;
+		}
+	}
+
+	return 4;
+}

kwin/kompmgr/kompmgr.c

@@ -389,7 +389,8 @@ void delete_pid_file()
         printf("kompmgr lost connection to X server, restarting...\n\r"); fflush(stdout);
         sleep(1);
         char me[2048];
-        readlink("/proc/self/exe", me, sizeof(me));
+        int chars = readlink("/proc/self/exe", me, sizeof(me));
+        me[chars] = 0;
         me[2047] = 0;
 	execl(me, NULL);
     }