From 750dee2eded3b1c16e0434fa387d35a869545d9e Mon Sep 17 00:00:00 2001
From: Stephen Gallagher <sgallagh@redhat.com>
Date: Wed, 15 Feb 2023 15:49:38 -0500
Subject: [PATCH 1/2] Extend maximum DNS name to 255

The hostname part is still restricted to 63 characters

See RFC 1035, section 2.3.4

Signed-off-by: Stephen Gallagher <sgallagh@redhat.com>
---
 include/sscg.h  |  3 +++
 src/arguments.c | 35 +++++++++++++++++++++++++++--------
 src/authority.c | 26 +++++++++++++++++++++++---
 src/cert.c      |  5 +++++
 src/x509.c      |  6 +++---
 5 files changed, 61 insertions(+), 14 deletions(-)

diff --git a/include/sscg.h b/include/sscg.h
index 0f35631018dc2745e986cd1e7e094e3e37be8e54..f0c6d93b871e4bd3f2c805be8dfa7485ec34746a 100644
--- a/include/sscg.h
+++ b/include/sscg.h
@@ -313,6 +313,9 @@ enum sscg_cert_type
 #define SSCG_MIN_KEY_PASS_LEN 4
 #define SSCG_MAX_KEY_PASS_LEN 1023
 
+/* RFC 1035, section 2.3.4 (Size Limits) */
+#define MAX_HOST_LEN 63
+#define MAX_FQDN_LEN 255
 
 int
 sscg_handle_arguments (TALLOC_CTX *mem_ctx,
diff --git a/src/arguments.c b/src/arguments.c
index 0b7a060d31bed97130c7cb9b7feacf0876e25c0d..2f412bee1bee9620f28b6e84aed4aef17aee3a6a 100644
--- a/src/arguments.c
+++ b/src/arguments.c
@@ -786,10 +786,19 @@ sscg_handle_arguments (TALLOC_CTX *mem_ctx,
     }
   CHECK_MEM (options->hostname);
 
-  if (strnlen (options->hostname, MAXHOSTNAMELEN + 1) > MAXHOSTNAMELEN)
+  if (strnlen (options->hostname, MAX_FQDN_LEN + 1) > MAX_FQDN_LEN)
     {
-      fprintf (
-        stderr, "Hostnames may not exceed %d characters\n", MAXHOSTNAMELEN);
+      fprintf (stderr, "FQDNs may not exceed %d characters\n", MAX_FQDN_LEN);
+      ret = EINVAL;
+      goto done;
+    }
+
+  if ((strchr (options->hostname, '.') - options->hostname) > MAX_HOST_LEN + 4)
+    {
+      fprintf (stderr,
+               "Hostnames may not exceed %d characters in Subject "
+               "Alternative Names\n",
+               MAX_HOST_LEN);
       ret = EINVAL;
       goto done;
     }
@@ -798,25 +807,35 @@ sscg_handle_arguments (TALLOC_CTX *mem_ctx,
        options struct. It's not the most efficient approach, but
        it's only done one time, so there is no sense in optimizing
        it. */
+  size_t i = 0;
   if (alternative_names)
     {
-      size_t i = 0;
       while (alternative_names[i] != NULL)
         {
           options->subject_alt_names = talloc_realloc (
-            options, options->subject_alt_names, char *, i + 2);
+            options, options->subject_alt_names, char *, i + 1);
           CHECK_MEM (options->subject_alt_names);
 
           options->subject_alt_names[i] =
             talloc_strdup (options->subject_alt_names, alternative_names[i]);
           CHECK_MEM (options->subject_alt_names[i]);
-
-          /* Add a NULL terminator to the end */
-          options->subject_alt_names[i + 1] = NULL;
           i++;
         }
     }
 
+  /*
+    The hostname must always be listed in SubjectAlternativeNames as well.
+    Note that the realloc also adds an extra entry for the NULL terminator
+  */
+  options->subject_alt_names =
+    talloc_realloc (options, options->subject_alt_names, char *, i + 2);
+  CHECK_MEM (options->subject_alt_names);
+  options->subject_alt_names[i] =
+    talloc_strdup (options->subject_alt_names, options->hostname);
+  CHECK_MEM (options->subject_alt_names[i]);
+  /* Add a NULL terminator to the end */
+  options->subject_alt_names[i + 1] = NULL;
+
   if (options->key_strength < options->minimum_key_strength)
     {
       fprintf (stderr,
diff --git a/src/authority.c b/src/authority.c
index 4efaa9e730964b9762b59d0e6698c1623901ccfe..f509fd4316c3b7b230f99de6464491c319fc5d45 100644
--- a/src/authority.c
+++ b/src/authority.c
@@ -56,6 +56,7 @@ create_private_CA (TALLOC_CTX *mem_ctx,
   char *name_constraint;
   char *san;
   char *tmp;
+  char *dot;
 
   tmp_ctx = talloc_new (NULL);
   CHECK_MEM (tmp_ctx);
@@ -89,6 +90,26 @@ create_private_CA (TALLOC_CTX *mem_ctx,
 
   ca_certinfo->cn = talloc_strdup (ca_certinfo, options->hostname);
   CHECK_MEM (ca_certinfo->cn);
+  /* Truncate the CN at the first dot */
+  if ((dot = strchr (ca_certinfo->cn, '.')))
+    *dot = '\0';
+
+  if (options->subject_alt_names)
+    {
+      for (i = 0; options->subject_alt_names[i]; i++)
+        {
+          ca_certinfo->subject_alt_names = talloc_realloc (
+            ca_certinfo, ca_certinfo->subject_alt_names, char *, i + 2);
+          CHECK_MEM (ca_certinfo->subject_alt_names);
+
+          ca_certinfo->subject_alt_names[i] = talloc_strdup (
+            ca_certinfo->subject_alt_names, options->subject_alt_names[i]);
+          CHECK_MEM (ca_certinfo->subject_alt_names[i]);
+
+          /* Add a NULL terminator to the end */
+          ca_certinfo->subject_alt_names[i + 1] = NULL;
+        }
+    }
 
   /* Make this a CA certificate */
 
@@ -106,10 +127,9 @@ create_private_CA (TALLOC_CTX *mem_ctx,
   CHECK_MEM (ex);
   sk_X509_EXTENSION_push (ca_certinfo->extensions, ex);
 
-  /* Restrict signing to the hostname and subjectAltNames of the
-       service certificate */
+  /* Restrict signing to the CN and subjectAltNames of the service certificate */
   name_constraint =
-    talloc_asprintf (tmp_ctx, "permitted;DNS:%s", options->hostname);
+    talloc_asprintf (tmp_ctx, "permitted;DNS:%s", ca_certinfo->cn);
   CHECK_MEM (name_constraint);
 
   if (options->subject_alt_names)
diff --git a/src/cert.c b/src/cert.c
index 99d9109f5981ef408aeb7d05a8327e1a38d5700a..e36de71e7ca9b34f87734542d5646b466cd61d4c 100644
--- a/src/cert.c
+++ b/src/cert.c
@@ -31,6 +31,7 @@
 */
 
 
+#include <string.h>
 #include "include/sscg.h"
 #include "include/cert.h"
 #include "include/x509.h"
@@ -52,6 +53,7 @@ create_cert (TALLOC_CTX *mem_ctx,
   struct sscg_x509_req *csr;
   struct sscg_evp_pkey *pkey;
   struct sscg_x509_cert *cert;
+  char *dot;
   X509_EXTENSION *ex = NULL;
   EXTENDED_KEY_USAGE *extended;
   TALLOC_CTX *tmp_ctx = NULL;
@@ -87,6 +89,9 @@ create_cert (TALLOC_CTX *mem_ctx,
 
   certinfo->cn = talloc_strdup (certinfo, options->hostname);
   CHECK_MEM (certinfo->cn);
+  /* Truncate the CN at the first dot */
+  if ((dot = strchr (certinfo->cn, '.')))
+    *dot = '\0';
 
   if (options->subject_alt_names)
     {
diff --git a/src/x509.c b/src/x509.c
index 4f3f11cd3411f00cf6de3a72ba897adc97944e35..9f6f21b49c2dd70629fed67d327027374eb21b15 100644
--- a/src/x509.c
+++ b/src/x509.c
@@ -290,12 +290,12 @@ sscg_x509v3_csr_new (TALLOC_CTX *mem_ctx,
             }
           CHECK_MEM (san);
 
-          if (strnlen (san, MAXHOSTNAMELEN + 5) > MAXHOSTNAMELEN + 4)
+          if (strnlen (san, MAX_FQDN_LEN + 5) > MAX_FQDN_LEN + 4)
             {
               fprintf (stderr,
-                       "Hostnames may not exceed %d characters in Subject "
+                       "FQDNs may not exceed %d characters in Subject "
                        "Alternative Names\n",
-                       MAXHOSTNAMELEN);
+                       MAX_FQDN_LEN);
               ret = EINVAL;
               goto done;
             }
-- 
2.41.0