From 69c8e20b18577781e17c5959e23514134dfb5755 Mon Sep 17 00:00:00 2001

From: Nalin Dahyabhai <nalin@redhat.com>

Date: Thu, 24 Jul 2014 16:43:21 -0400

Subject: [PATCH 6/7] Use more randomness for ksu secondary cache names

When generating a suffix to append to a ccache name that will hold the

credentials for a ksu-invoked process, instead of using integers

counting up from 1, use the result of base64-encoding six randomly-

generated octets.  Tweak the output alphabet just a bit to avoid using

'+' or '/' in the generated names, the latter of which could really

confuse things.

---

 src/clients/ksu/ccache.c | 27 +++++++++++++++++++++++----

 src/clients/ksu/ksu.h    |  2 +-

 src/clients/ksu/main.c   | 16 ++++++++++++----

 3 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/src/clients/ksu/ccache.c b/src/clients/ksu/ccache.c

index 0f9e042..a0736f2 100644

--- a/src/clients/ksu/ccache.c

+++ b/src/clients/ksu/ccache.c

@@ -27,6 +27,7 @@

  */

 #include "ksu.h"

+#include "k5-base64.h"

 #include "adm_proto.h"

 #include <sys/types.h>

 #include <sys/stat.h>

@@ -504,10 +505,28 @@ show_credential(context, cred, cc)

     free(sname);

 }

-int gen_sym(){

-    static int i = 0;

-    i ++;

-    return i;

+/* Create a random string suitable for a filename extension. */

+krb5_error_code

+gen_sym(krb5_context context, char **sym_out)

+{

+    krb5_error_code retval;

+    char bytes[6], *p, *sym;

+    krb5_data data = make_data(bytes, sizeof(bytes));

+

+    *sym_out = NULL;

+    retval = krb5_c_random_make_octets(context, &data);

+    if (retval)

+        return retval;

+    sym = k5_base64_encode(data.data, data.length);

+    if (sym == NULL)

+        return ENOMEM;

+    /* Tweak the output alphabet just a bit. */

+    while ((p = strchr(sym, '/')) != NULL)

+        *p = '_';

+    while ((p = strchr(sym, '+')) != NULL)

+        *p = '-';

+    *sym_out = sym;

+    return 0;

 }

 krb5_error_code krb5_ccache_overwrite(context, ccs, cct, primary_principal)

diff --git a/src/clients/ksu/ksu.h b/src/clients/ksu/ksu.h

index fbbf217..5ba5ceb 100644

--- a/src/clients/ksu/ksu.h

+++ b/src/clients/ksu/ksu.h

@@ -130,7 +130,7 @@ extern krb5_error_code krb5_get_login_princ

 extern void show_credential

 (krb5_context, krb5_creds *, krb5_ccache);

-extern int gen_sym (void);

+krb5_error_code gen_sym(krb5_context context, char **sym);

 extern krb5_error_code krb5_ccache_overwrite

 (krb5_context, krb5_ccache, krb5_ccache, krb5_principal);

diff --git a/src/clients/ksu/main.c b/src/clients/ksu/main.c

index 41a3bf8..47fa820 100644

--- a/src/clients/ksu/main.c

+++ b/src/clients/ksu/main.c

@@ -856,7 +856,7 @@ resolve_target_cache(krb5_context context, krb5_principal princ,

     krb5_error_code retval;

     krb5_boolean switchable, reused = FALSE;

     krb5_ccache ccache = NULL;

-    char *sep, *ccname = NULL, *target;

+    char *sep, *ccname = NULL, *sym = NULL, *target;

     *ccache_out = NULL;

     *ccache_reused = FALSE;

@@ -876,12 +876,20 @@ resolve_target_cache(krb5_context context, krb5_principal princ,

          * the name of a cache that doesn't exist yet. */

         do {

             free(ccname);

-            if (asprintf(&ccname, "%s.%d", target, gen_sym()) < 0) {

+            retval = gen_sym(context, &sym);

+            if (retval) {

+                com_err(prog_name, retval,

+                        _("while generating part of the target ccache name"));

+                return retval;

+            }

+            if (asprintf(&ccname, "%s.%s", target, sym) < 0) {

                 retval = ENOMEM;

-                com_err(prog_name, ENOMEM,

-                        _("while allocating memory for target ccache name"));

+                free(sym);

+                com_err(prog_name, retval, _("while allocating memory for the "

+                                             "target ccache name"));

                 goto cleanup;

             }

+            free(sym);

         } while (ks_ccache_name_is_initialized(context, ccname));

         retval = krb5_cc_resolve(context, ccname, &ccache);

     } else {

-- 

2.0.4