[SSSD] [PATCH] krb5: Check return value of sss_krb5_princ_realm

Lukas Slebodnik lslebodn at redhat.com
Tue Oct 14 12:44:49 UTC 2014


On (14/10/14 14:14), Pavel Reichl wrote:
>
>On 10/14/2014 01:59 PM, Lukas Slebodnik wrote:
>>diff --git a/src/util/sss_krb5.c b/src/util/sss_krb5.c
>>index b4012593d96bc951143e4bb2ba7a91d118b1a53c..7daedb47464917966350f94c7d5b0844ccee7edb 100644
>>--- a/src/util/sss_krb5.c
>>+++ b/src/util/sss_krb5.c
>>@@ -834,8 +834,15 @@ void sss_krb5_get_init_creds_opt_set_canonicalize(krb5_get_init_creds_opt *opts,
>>  void sss_krb5_princ_realm(krb5_context context, krb5_const_principal princ,
>>                            const char **realm, int *len)
>>  {
>>-    *realm = krb5_principal_get_realm(context, princ);
>>-    *len = strlen(*realm);
>>+    const char *realm_str = krb5_principal_get_realm(context, princ);
>>+
>>+    if (realm_str != NULL) {
>>+        *realm = krb5_principal_get_realm(context, princ);
>
>Why do we have to call krb5_principal_get_realm() again here? Why can't we
>just reuse value in realm_str?
>
I just forgot to squash changes before sending patches.

Updated version is attached.

LS
-------------- next part --------------
>From dd5c7ea4ebc0002e529dafeceececcbdcc96e7cc Mon Sep 17 00:00:00 2001
From: Lukas Slebodnik <lslebodn at redhat.com>
Date: Tue, 14 Oct 2014 11:20:40 +0200
Subject: [PATCH] krb5: Check return value of krb5_principal_get_realm

Function krb5_principal_get_realm can return NULL an it would
case segfault in function strlen.
---
 src/util/sss_krb5.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/util/sss_krb5.c b/src/util/sss_krb5.c
index b4012593d96bc951143e4bb2ba7a91d118b1a53c..38d44e51926bc99c6e53851d7814b6d0be254086 100644
--- a/src/util/sss_krb5.c
+++ b/src/util/sss_krb5.c
@@ -834,8 +834,15 @@ void sss_krb5_get_init_creds_opt_set_canonicalize(krb5_get_init_creds_opt *opts,
 void sss_krb5_princ_realm(krb5_context context, krb5_const_principal princ,
                           const char **realm, int *len)
 {
-    *realm = krb5_principal_get_realm(context, princ);
-    *len = strlen(*realm);
+    const char *realm_str = krb5_principal_get_realm(context, princ);
+
+    if (realm_str != NULL) {
+        *realm = realm_str;
+        *len = strlen(realm_str);
+    } else {
+        *realm = NULL;
+        *len = 0;
+    }
 }
 #else
 void sss_krb5_princ_realm(krb5_context context, krb5_const_principal princ,
-- 
2.1.0

-------------- next part --------------
>From a18938ac0f0c1bc259aed527ce34f274d0fd0473 Mon Sep 17 00:00:00 2001
From: Lukas Slebodnik <lslebodn at redhat.com>
Date: Mon, 14 Oct 2013 11:21:02 +0200
Subject: [PATCH 2/2] krb5: Check return value of sss_krb5_princ_realm

sss_krb5_princ_realm set output parameter realm to NULL and len to 0
in case of failure. Clang static analysers reported warning
"Null pointer passed as an argument to a 'nonnull' parameter"
in function match_principal. It was possible, that realm_name with value NULL
could be used in strncmp.
---
 src/providers/krb5/krb5_child.c |  8 ++++++++
 src/providers/krb5/krb5_utils.c |  5 +++++
 src/util/sss_krb5.c             | 13 +++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/src/providers/krb5/krb5_child.c b/src/providers/krb5/krb5_child.c
index 945f4c76ec48b594a8033438251cb0d913ddcf0c..0aa7abb8283956c7eb9d36a2b1ebaee0ae4a26c6 100644
--- a/src/providers/krb5/krb5_child.c
+++ b/src/providers/krb5/krb5_child.c
@@ -969,6 +969,10 @@ static krb5_error_code get_and_save_tgt(struct krb5_req *kr,
     }
 
     sss_krb5_princ_realm(kr->ctx, kr->princ, &realm_name, &realm_length);
+    if (realm_length == 0) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "sss_krb5_princ_realm failed.\n");
+        return KRB5KRB_ERR_GENERIC;
+    }
 
     DEBUG(SSSDBG_TRACE_FUNC,
           "Attempting kinit for realm [%s]\n",realm_name);
@@ -1112,6 +1116,10 @@ static errno_t changepw_child(struct krb5_req *kr, bool prelim)
 
     set_changepw_options(kr->options);
     sss_krb5_princ_realm(kr->ctx, kr->princ, &realm_name, &realm_length);
+    if (realm_length == 0) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "sss_krb5_princ_realm failed.\n");
+        return ERR_INTERNAL;
+    }
 
     DEBUG(SSSDBG_TRACE_FUNC,
           "Attempting kinit for realm [%s]\n",realm_name);
diff --git a/src/providers/krb5/krb5_utils.c b/src/providers/krb5/krb5_utils.c
index 0d2e281198390043068e21b412b57de04df6a12b..4f578e4df9fe5b87781e02555c619e4445196202 100644
--- a/src/providers/krb5/krb5_utils.c
+++ b/src/providers/krb5/krb5_utils.c
@@ -653,6 +653,11 @@ errno_t get_ccache_file_data(const char *ccache_file, const char *client_name,
     }
 
     sss_krb5_princ_realm(ctx, client_princ, &realm_name, &realm_length);
+    if (realm_length == 0) {
+        kerr = KRB5KRB_ERR_GENERIC;
+        DEBUG(SSSDBG_CRIT_FAILURE, "sss_krb5_princ_realm failed.\n");
+        goto done;
+    }
 
     server_name = talloc_asprintf(NULL, "krbtgt/%.*s@%.*s",
                                   realm_length, realm_name,
diff --git a/src/util/sss_krb5.c b/src/util/sss_krb5.c
index 7daedb47464917966350f94c7d5b0844ccee7edb..0cfb3873bd5a5d94c704f98ffd7388ead497b2f5 100644
--- a/src/util/sss_krb5.c
+++ b/src/util/sss_krb5.c
@@ -212,6 +212,15 @@ errno_t select_principal_from_keytab(TALLOC_CTX *mem_ctx,
             sss_krb5_princ_realm(krb_ctx, client_princ,
                                  &realm_name,
                                  &realm_len);
+            if (realm_len == 0) {
+                DEBUG(SSSDBG_CRIT_FAILURE, "sss_krb5_princ_realm failed.\n");
+                if (_principal) talloc_zfree(*_principal);
+                if (_primary) talloc_zfree(*_primary);
+                ret = EINVAL;
+                goto done;
+
+            }
+
             *_realm = talloc_asprintf(mem_ctx, "%.*s",
                                       realm_len, realm_name);
             if (!*_realm) {
@@ -355,6 +364,10 @@ static bool match_principal(krb5_context ctx,
     bool ret = false;
 
     sss_krb5_princ_realm(ctx, principal, &realm_name, &realm_len);
+    if (realm_len == 0) {
+        DEBUG(SSSDBG_MINOR_FAILURE, "sss_krb5_princ_realm failed.\n");
+        return false;
+    }
 
     tmp_ctx = talloc_new(NULL);
     if (!tmp_ctx) {
-- 
2.1.0



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