redo notetaker program using setuid to run as root and insert uid of user running program.

2 files changed, 76 insertions, 0 deletions

diff --git a/hacking.h b/hacking.h
new file mode 100644
index 0000000..2c9c805
--- /dev/null
+++ b/hacking.h
@@ -0,0 +1,18 @@
+
+void fatal(char *message)
+{
+  char error_message[100];
+  strcpy(error_message, "[!!] Fatal Error ");
+  strncat(error_message, message, 83);
+  perror(error_message);
+  exit(-1);
+}
+
+void *ec_malloc(unsigned int size)
+{
+  void *ptr;
+  ptr = malloc(size);
+  if (ptr == NULL)
+    fatal("in ec_malloc() on memory allocation");
+  return ptr;
+}
diff --git a/notetaker.c b/notetaker.c
new file mode 100644
index 0000000..a1c58f3
--- /dev/null
+++ b/notetaker.c
@@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include "hacking.h"
+
+void usage(const char *program_name, char *filename)
+{
+  printf("Usage: %s <data to add to %s>\n", program_name, filename);
+  exit(0);
+}
+
+void fatal(char *);
+void *ec_malloc(unsigned int);
+
+int main(int argc, const char *argv[])
+{
+  int userid, fd;
+  char *buffer, *datafile;
+
+  buffer = (char *) ec_malloc(100);
+  datafile = (char *) ec_malloc(20);
+  strcpy(datafile, "/var/notes");
+
+  if (argc < 2)
+    usage(argv[0], datafile);
+
+  strcpy(buffer, argv[1]);
+
+  printf("[DEBUG] buffer @ %p: \'%s\'\n", buffer, buffer);
+  printf("[DEBUG] datafile @ %p: \'%s\'\n", datafile, datafile);
+
+  fd = open(datafile, O_WRONLY|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR);
+  if (fd == -1)
+    fatal("in main() while opening file");
+
+  printf("[DEBUG] file descriptor is %d\n", fd);
+  userid = getuid();
+
+  if (write(fd, &userid, 4) == -1)
+    fatal("in main() while writing userid to file");
+  write(fd, "\n", 1);
+
+  if(write(fd, buffer, strlen(buffer)) == -1)
+    fatal("in main() while writing buffer to file");
+  write(fd, "\n", 1);
+
+  if(close(fd) == -1)
+    fatal("in main() while closing file");
+
+  printf("Note has been saved.\n");
+  free(buffer);
+  free(datafile);
+
+  return 0;
+}