seteuid() or setuid() before chdir() (more secure)

determine user's identity by his uid, not the var USER
(in order to act as crontab).

diff --git a/fcrontab.c b/fcrontab.c
index 1ef2ef5406bd21d2ebf1af5eb7e230862aa2d5be..6ff660fa42005ac44fb44e3965498dc92a00df6f 100644 (file)
--- a/fcrontab.c
+++ b/fcrontab.c
@@ -22,7 +22,7 @@
  *  `LICENSE' that comes with the fcron source distribution.
  */
 
- /* $Id: fcrontab.c,v 1.24 2000-12-16 19:01:38 thib Exp $ */
+ /* $Id: fcrontab.c,v 1.25 2000-12-20 14:11:26 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 1.24 2000-12-16 19:01:38 thib Exp $";
+char rcs_info[] = "$Id: fcrontab.c,v 1.25 2000-12-20 14:11:26 thib Exp $";
 
 void info(void);
 void usage(void);
@@ -666,6 +666,7 @@ parseopt(int argc, char *argv[])
     char c;
     extern char *optarg;
     extern int optind, opterr, optopt;
+    struct passwd *pass;
 
     /* constants and variables defined by command line */
 
@@ -692,6 +693,11 @@ parseopt(int argc, char *argv[])
            debug_opt = 1; break;
 
        case 'l':
+           if (rm_opt || edit_opt || reinstall_opt) {
+               fprintf(stderr, "Only one of the options -l, -r, -e and -z"
+                       "can be used simultaneously.\n");
+               xexit(EXIT_ERR);
+           }
            list_opt = 1;
            rm_opt = 0;
            edit_opt = 0;
@@ -699,6 +705,11 @@ parseopt(int argc, char *argv[])
            break;
 
        case 'r':
+           if (list_opt || edit_opt || reinstall_opt) {
+               fprintf(stderr, "Only one of the options -l, -r, -e and -z"
+                       "can be used simultaneously.\n");
+               xexit(EXIT_ERR);
+           }
            list_opt = 0;
            rm_opt = 1;
            edit_opt = 0;
@@ -706,6 +717,11 @@ parseopt(int argc, char *argv[])
            break;
 
        case 'e':
+           if (list_opt || rm_opt || reinstall_opt) {
+               fprintf(stderr, "Only one of the options -l, -r, -e and -z"
+                       "can be used simultaneously.\n");
+               xexit(EXIT_ERR);
+           }
            list_opt = 0;
            rm_opt = 0;
            edit_opt = 1;
@@ -713,6 +729,11 @@ parseopt(int argc, char *argv[])
            break;
 
        case 'z':
+           if (list_opt || rm_opt || edit_opt) {
+               fprintf(stderr, "Only one of the options -l, -r, -e and -z"
+                       "can be used simultaneously.\n");
+               xexit(EXIT_ERR);
+           }
            list_opt = 0;
            rm_opt = 0;
            edit_opt = 0;
@@ -736,17 +757,16 @@ parseopt(int argc, char *argv[])
     }
 
     if ( user == NULL ) {
-       /* we need to strdup2 the value given by getenv() because we free
+       /* get user's name using getpwuid() */
+       if ( ! (pass = getpwuid(uid)) )
+           die("user '%s' is not in passwd file. Aborting.", USERNAME);
+       /* we need to strdup2 the value given by getpwuid() because we free
         * file->cf_user in delete_file */
-       if ((user = strdup2(getenv("USER"))) == NULL) {
-           fprintf(stderr, "Could not get user name.\n");
-           xexit(EXIT_ERR);
-       }
-       asuid = getuid();
-       asgid = getgid();
+       user = strdup2(pass->pw_name);
+       asuid = pass->pw_uid;
+       asgid = pass->pw_gid;
     }
     else {
-       struct passwd *pass;
        if ( ! (pass = getpwnam(user)) )
            die("user '%s' is not in passwd file. Aborting.", user);
        asuid = pass->pw_uid;
@@ -773,11 +793,11 @@ main(int argc, char **argv)
     if (strrchr(argv[0],'/')==NULL) prog_name = argv[0];
     else prog_name = strrchr(argv[0],'/')+1;
 
+    uid = getuid();
+
     /* interpret command line options */
     parseopt(argc, argv);
 
-    uid = getuid();
-
 #if defined(HAVE_SETREGID) && defined(HAVE_SETREUID)
     {
        struct passwd *pass;
@@ -785,6 +805,16 @@ main(int argc, char **argv)
            die("user '%s' is not in passwd file. Aborting.", USERNAME);
        fcrontab_uid = pass->pw_uid;
        fcrontab_gid = pass->pw_gid;
+
+       if (uid != fcrontab_uid)
+           if (seteuid(fcrontab_uid) != 0) 
+               die_e("Could not change uid to fcrontab_uid[%d]",fcrontab_uid);
+       /* change directory */
+       if (chdir(cdir) != 0) {
+           error_e("Could not chdir to " FCRONTABS );
+           xexit (EXIT_ERR);
+       }
+       /* get user's permissions */
        if (seteuid(uid) != 0) 
            die_e("Could not change uid to uid[%d]", uid); 
        if (setegid(fcrontab_gid) != 0) 
@@ -795,6 +825,11 @@ main(int argc, char **argv)
        die_e("Could not change uid to 0"); 
     if (setgid(0) != 0)
        die_e("Could not change gid to 0");
+    /* change directory */
+    if (chdir(cdir) != 0) {
+       error_e("Could not chdir to " FCRONTABS );
+       xexit (EXIT_ERR);
+    }
 #endif
     
 
@@ -806,12 +841,6 @@ main(int argc, char **argv)
     if ( (orig_dir = getcwd(NULL, 0)) == NULL )
        error_e("getcwd");
 
-    /* change directory */
-    if (chdir(cdir) != 0) {
-       error_e("Could not chdir to " FCRONTABS );
-       xexit (EXIT_ERR);
-    }
-
     snprintf(buf, sizeof(buf), "%s.orig", user);
 
     /* determine what action should be taken */