[or-cvs] fixed a bug in the id switching code -- setgid has to happe...

[Steven Hazel]

Update of /home/or/cvsroot/src/common
In directory moria.mit.edu:/home/sah/tor/src/common

Modified Files:
	util.h util.c 
Log Message:
- fixed a bug in the id switching code -- setgid has to happen before
  setuid, because after we setuid we don't have the priviledges we
  need to setgid anymore, duh.  merged switch_user() and
  switch_group() into switch_id(), since that code has to be wound
  together.

- return -1 from switch_id() if it's not defined to do anything else.

- moved daemoinize(), write_pidfile(), and switch_id() from main.c to
  util.c


Index: util.h
===================================================================
RCS file: /home/or/cvsroot/src/common/util.h,v
retrieving revision 1.20
retrieving revision 1.21
diff -u -d -r1.20 -r1.21
--- util.h	21 Oct 2003 09:48:58 -0000	1.20
+++ util.h	22 Oct 2003 11:21:29 -0000	1.21
@@ -64,6 +64,10 @@
 
 const char *get_uname(void);
 
+void daemonize(void);
+void write_pidfile(char *filename);
+int switch_id(char *user, char *group);
+
 /* For stupid historical reasons, windows sockets have an independent set of 
  * errnos which they use as the fancy strikes them.
  */

Index: util.c
===================================================================
RCS file: /home/or/cvsroot/src/common/util.c,v
retrieving revision 1.33
retrieving revision 1.34
diff -u -d -r1.33 -r1.34
--- util.c	20 Oct 2003 20:19:56 -0000	1.33
+++ util.c	22 Oct 2003 11:21:29 -0000	1.34
@@ -547,3 +547,91 @@
   return uname_result;
 }
       
+void daemonize(void) {
+#ifndef MS_WINDOWS
+  /* Fork; parent exits. */
+  if (fork())
+    exit(0);
+
+  /* Create new session; make sure we never get a terminal */
+  setsid();
+  if (fork())
+    exit(0);
+
+  chdir("/");
+  umask(000);
+
+  fclose(stdin);
+  fclose(stdout);
+  fclose(stderr);
+#endif
+}
+
+void write_pidfile(char *filename) {
+#ifndef MS_WINDOWS
+  FILE *pidfile;
+
+  if ((pidfile = fopen(filename, "w")) == NULL) {
+    log_fn(LOG_WARN, "unable to open %s for writing: %s", filename,
+           strerror(errno));
+  } else {
+    fprintf(pidfile, "%d", getpid());
+    fclose(pidfile);
+  }
+#endif
+}
+
+int switch_id(char *user, char *group) {
+#ifndef MS_WINDOWS
+  int status;
+  struct passwd *pw = NULL;
+  struct group *gr = NULL;
+
+  if (user) {
+    pw = getpwnam(user);
+    if (pw == NULL) {
+      log_fn(LOG_ERR,"User '%s' not found.", user);
+      return -1;
+    }
+  }
+
+  /* switch the group first, while we still have the priveledges to do so */
+  if (group) {
+    gr = getgrnam(group);
+    if (gr == NULL) {
+      log_fn(LOG_ERR,"Group '%s' not found.", group);
+      return -1;
+    }
+
+    status = setgid(gr->gr_gid);
+    if (status != 0) {
+      log_fn(LOG_ERR,"Error setting GID: %s", strerror(errno));
+      return -1;
+    }
+  } else if (user) {
+    status = setgid(pw->pw_gid);
+    if (status != 0) {
+      log_fn(LOG_ERR,"Error setting GID: %s", strerror(errno));
+      return -1;
+    }
+  }
+
+  /* now that the group is switched, we can switch users and lose
+     priviledges */
+  if (user) {
+    status = setuid(pw->pw_uid);
+    if (status != 0) {
+      log_fn(LOG_ERR,"Error setting UID: %s", strerror(errno));
+      return -1;
+    }
+  }
+
+  return 0;
+#endif
+
+  log_fn(LOG_ERR, 
+         "User '%s' specified, but switching users is not supported.", 
+         user);
+
+  return -1;
+}