security fix : used to be able to read root files when running fcrontab -u user -e

(race condition and symlink)

diff --git a/fcrontab.c b/fcrontab.c
index 0ee0e73244f8b61e67cf7d65494d2282c158cc48..8cef5353360fdfec7be28237489d61c56f7596b2 100644 (file)
--- a/fcrontab.c
+++ b/fcrontab.c
@@ -22,7 +22,7 @@
  *  `LICENSE' that comes with the fcron source distribution.
  */
 
- /* $Id: fcrontab.c,v 1.31 2001-02-14 13:51:14 thib Exp $ */
+ /* $Id: fcrontab.c,v 1.32 2001-02-26 11:11:10 thib Exp $ */
 
 /* 
  * The goal of this program is simple : giving a user interface to fcron
@@ -42,7 +42,7 @@
 
 #include "fcrontab.h"
 
-char rcs_info[] = "$Id: fcrontab.c,v 1.31 2001-02-14 13:51:14 thib Exp $";
+char rcs_info[] = "$Id: fcrontab.c,v 1.32 2001-02-26 11:11:10 thib Exp $";
 
 void info(void);
 void usage(void);
@@ -464,15 +464,12 @@ edit_file(char *buf)
        error_e("could not fdopen");
        goto exiterr;
     }
-#if defined(HAVE_SETREGID) && defined(HAVE_SETREUID)
-    if (uid == 0)
-#else
-    if (1)
+#if ! (defined(HAVE_SETREGID) && defined(HAVE_SETREUID))
+    if (fchown(file, asuid, asgid) != 0) {
+       error_e("Could not fchown %s to asuid and asgid", tmp);
+       goto exiterr;
+    }
 #endif
-       if (fchown(file, asuid, asgid) != 0) {
-           error_e("Could not fchown %s to asuid and asgid", tmp);
-           goto exiterr;
-       }
     /* copy user's fcrontab (if any) to a temp file */
     if ( (f = fopen(buf, "r")) == NULL ) {
        if ( errno != ENOENT ) {
@@ -505,18 +502,16 @@ edit_file(char *buf)
        switch ( pid = fork() ) {
        case 0:
            /* child */
-           if (uid == 0)
-               /* we need to become root to perform the gid and uid changes */
-               if (setreuid(0, 0) != 0)
-                   error_e("setreuid(0, 0)");
 #if defined(HAVE_SETREGID) && defined(HAVE_SETREUID)
-           if (setregid(asgid, asgid) < 0) {
-               error_e("setregid(asgid, asgid)");
-               goto exiterr;
-           }
-           if (setreuid(asuid, asuid) < 0) {
-               error_e("setreuid(asuid, asuid)");
-               goto exiterr;
+           if (uid != 0) {
+               if (setregid(asgid, asgid) < 0) {
+                   error_e("setregid(asgid, asgid)");
+                   goto exiterr;
+               }
+               if (setreuid(asuid, asuid) < 0) {
+                   error_e("setreuid(asuid, asuid)");
+                   goto exiterr;
+               }
            }
 #else
            if (setgid(asgid) < 0) {
@@ -549,13 +544,12 @@ edit_file(char *buf)
            goto exiterr;
        }
 
-
        /* check if file has been modified */
        if ( stat(tmp, &st) != 0 ) {
            error_e("could not stat %s", tmp);
            goto exiterr;
-       }
-    
+       }    
+
        else if ( st.st_mtime > mtime || correction == 1) {
 
            correction = 0;