gpgsm: New option --compatibility-flags.

* sm/gpgsm.c (oCompatibilityFlags): New option.
(compatibility_flags): new.
(main): Parse and print them in verbose mode.
* sm/gpgsm.h (opt): Add field compat_glags.:
(COMPAT_ALLOW_KA_TO_ENCR): New.
* sm/keylist.c (print_capabilities): Take care of the new flag.
* sm/certlist.c (cert_usage_p): Ditto.

* common/miscellaneous.c (parse_compatibility_flags): New.
* common/util.h (struct compatibility_flags_s): New.
--

Backported-from-master: f0b373cec93bb01f02b9c0a3ab1f3e242b381c3f
Backported-from-master: ce63eaa4f8f3f41aafcaddd8d658dacd522334a8

7 files changed, 164 insertions, 9 deletions

diff --git a/common/miscellaneous.c b/common/miscellaneous.c
index e40dcd55f..c3775547b 100644
--- a/common/miscellaneous.c
+++ b/common/miscellaneous.c
@@ -760,3 +760,83 @@ parse_debug_flag (const char *string, unsigned int *debugvar,
   *debugvar |= result;
   return 0;
 }
+
+
+
+/* Parse an --comaptibility_flags style argument consisting of comma
+ * separated strings.
+ *
+ * Returns: 0 on success or -1 and ERRNO set on error.  On success the
+ *          supplied variable is updated by the parsed flags.
+ *
+ * If STRING is NULL the enabled flags are printed.
+ */
+int
+parse_compatibility_flags (const char *string, unsigned int *flagvar,
+                           const struct compatibility_flags_s *flags)
+
+{
+  unsigned long result = 0;
+  int i, j;
+
+  if (!string)
+    {
+      if (flagvar)
+        {
+          log_info ("enabled compatibility flags:");
+          for (i=0; flags[i].name; i++)
+            if ((*flagvar & flags[i].flag))
+              log_printf (" %s", flags[i].name);
+          log_printf ("\n");
+        }
+      return 0;
+    }
+
+  while (spacep (string))
+    string++;
+
+  if (!strcmp (string, "?") || !strcmp (string, "help"))
+    {
+      log_info ("available compatibility flags:\n");
+      for (i=0; flags[i].name; i++)
+        log_info (" %s\n", flags[i].name);
+      if (flags[i].flag != 77)
+        exit (0);
+    }
+  else
+    {
+      char **words;
+      words = strtokenize (string, ",");
+      if (!words)
+        return -1;
+      for (i=0; words[i]; i++)
+        {
+          if (*words[i])
+            {
+              for (j=0; flags[j].name; j++)
+                if (!strcmp (words[i], flags[j].name))
+                  {
+                    result |= flags[j].flag;
+                    break;
+                  }
+              if (!flags[j].name)
+                {
+                  if (!strcmp (words[i], "none"))
+                    {
+                      *flagvar = 0;
+                      result = 0;
+                    }
+                  else if (!strcmp (words[i], "all"))
+                    result = ~0;
+                  else
+                    log_info ("unknown compatibility flag '%s' ignored\n",
+                              words[i]);
+                }
+            }
+        }
+      xfree (words);
+    }
+
+  *flagvar |= result;
+  return 0;
+}
diff --git a/common/util.h b/common/util.h
index 9f46457ba..82b3a34af 100644
--- a/common/util.h
+++ b/common/util.h
@@ -358,6 +358,15 @@ struct debug_flags_s
 int parse_debug_flag (const char *string, unsigned int *debugvar,
                       const struct debug_flags_s *flags);
 
+struct compatibility_flags_s
+{
+  unsigned int flag;
+  const char *name;
+  const char *desc;
+};
+int parse_compatibility_flags (const char *string, unsigned int *flagvar,
+                               const struct compatibility_flags_s *flags);
+
 
 /*-- Simple replacement functions. */
 
diff --git a/doc/gpgsm.texi b/doc/gpgsm.texi
index 06a85b1ed..ba91aed92 100644
--- a/doc/gpgsm.texi
+++ b/doc/gpgsm.texi
@@ -710,6 +710,14 @@ Include ephemeral flagged keys in the output of key listings.  Note
 that they are included anyway if the key specification for a listing
 is given as fingerprint or keygrip.
 
+@item --compatibility-flags @var{flags}
+@opindex compatibility-flags
+Set compatibility flags to work around problems due to non-compliant
+certificates or data.  The @var{flags} are given as a comma separated
+list of flag names and are OR-ed together.  The special flag "none"
+clears the list and allows to start over with an empty list.  To get a
+list of available flags the sole word "help" can be used.
+
 @item --debug-level @var{level}
 @opindex debug-level
 Select the debug level for investigating problems. @var{level} may be
diff --git a/sm/certlist.c b/sm/certlist.c
index c3e4e821b..b1ae58c52 100644
--- a/sm/certlist.c
+++ b/sm/certlist.c
@@ -52,9 +52,11 @@ cert_usage_p (ksba_cert_t cert, int mode, int silent)
 {
   gpg_error_t err;
   unsigned int use;
+  unsigned int encr_bits, sign_bits;
   char *extkeyusages;
   int have_ocsp_signing = 0;
 
+
   err = ksba_cert_get_ext_key_usages (cert, &extkeyusages);
   if (gpg_err_code (err) == GPG_ERR_NO_DATA)
     err = 0; /* no policy given */
@@ -158,10 +160,13 @@ cert_usage_p (ksba_cert_t cert, int mode, int silent)
       return gpg_error (GPG_ERR_WRONG_KEY_USAGE);
     }
 
-  if ((use & ((mode&1)?
-              (KSBA_KEYUSAGE_KEY_ENCIPHERMENT|KSBA_KEYUSAGE_DATA_ENCIPHERMENT):
-              (KSBA_KEYUSAGE_DIGITAL_SIGNATURE|KSBA_KEYUSAGE_NON_REPUDIATION)))
-      )
+  encr_bits = (KSBA_KEYUSAGE_KEY_ENCIPHERMENT|KSBA_KEYUSAGE_DATA_ENCIPHERMENT);
+  if ((opt.compat_flags & COMPAT_ALLOW_KA_TO_ENCR))
+    encr_bits |= KSBA_KEYUSAGE_KEY_AGREEMENT;
+
+  sign_bits = (KSBA_KEYUSAGE_DIGITAL_SIGNATURE|KSBA_KEYUSAGE_NON_REPUDIATION);
+
+  if ((use & ((mode&1)? encr_bits : sign_bits)))
     return 0;
 
   if (!silent)
diff --git a/sm/gpgsm.c b/sm/gpgsm.c
index 87067cf31..27168904c 100644
--- a/sm/gpgsm.c
+++ b/sm/gpgsm.c
@@ -200,6 +200,7 @@ enum cmd_and_opt_values {
   oIgnoreCertExtension,
   oIgnoreCertWithOID,
   oRequireCompliance,
+  oCompatibilityFlags,
   oNoAutostart
  };
 
@@ -422,6 +423,7 @@ static ARGPARSE_OPTS opts[] = {
   ARGPARSE_s_s (oLCctype,    "lc-ctype", "@"),
   ARGPARSE_s_s (oLCmessages, "lc-messages", "@"),
   ARGPARSE_s_s (oXauthority, "xauthority", "@"),
+  ARGPARSE_s_s (oCompatibilityFlags, "compatibility-flags", "@"),
 
   ARGPARSE_header (NULL, ""),  /* Stop the header group.  */
 
@@ -457,6 +459,14 @@ static struct debug_flags_s debug_flags [] =
   };
 
 
+/* The list of compatibility flags.  */
+static struct compatibility_flags_s compatibility_flags [] =
+  {
+    { COMPAT_ALLOW_KA_TO_ENCR, "allow-ka-to-encr" },
+    { 0, NULL }
+  };
+
+
 /* Global variable to keep an error count. */
 int gpgsm_errors_seen = 0;
 
@@ -1233,6 +1243,15 @@ main ( int argc, char **argv)
         case oDebugNoChainValidation: opt.no_chain_validation = 1; break;
         case oDebugIgnoreExpiration: opt.ignore_expiration = 1; break;
 
+        case oCompatibilityFlags:
+          if (parse_compatibility_flags (pargs.r.ret_str, &opt.compat_flags,
+                                         compatibility_flags))
+            {
+              pargs.r_opt = ARGPARSE_INVALID_ARG;
+              pargs.err = ARGPARSE_PRINT_ERROR;
+            }
+          break;
+
         case oStatusFD:
             ctrl.status_fd = translate_sys2libc_fd_int (pargs.r.ret_int, 1);
             break;
@@ -1509,6 +1528,8 @@ main ( int argc, char **argv)
   gcry_control (GCRYCTL_RESUME_SECMEM_WARN);
 
   set_debug ();
+  if (opt.verbose) /* Print the compatibility flags.  */
+    parse_compatibility_flags (NULL, &opt.compat_flags, compatibility_flags);
   gnupg_set_compliance_extra_info (opt.min_rsa_length);
 
   /* Although we always use gpgsm_exit, we better install a regualr
diff --git a/sm/gpgsm.h b/sm/gpgsm.h
index 5e7db4bec..53ef165a1 100644
--- a/sm/gpgsm.h
+++ b/sm/gpgsm.h
@@ -150,6 +150,8 @@ struct
    * mode.  */
   int require_compliance;
 
+  /* Compatibility flags (COMPAT_FLAG_xxxx).  */
+  unsigned int compat_flags;
 } opt;
 
 /* Debug values and macros.  */
@@ -169,6 +171,18 @@ struct
 #define DBG_HASHING (opt.debug & DBG_HASHING_VALUE)
 #define DBG_IPC     (opt.debug & DBG_IPC_VALUE)
 
+
+/* Compatibility flags */
+/* Telesec RSA cards produced for NRW in 2022 came with only the
+ * keyAgreement bit set.  This flag allows there use for encryption
+ * anyway.  Example cert:
+ *    Issuer: /CN=DOI CA 10a/OU=DOI/O=PKI-1-Verwaltung/C=DE
+ * key usage: digitalSignature nonRepudiation keyAgreement
+ *  policies: 1.3.6.1.4.1.7924.1.1:N:
+ */
+#define COMPAT_ALLOW_KA_TO_ENCR   1
+
+
 /* Forward declaration for an object defined in server.c */
 struct server_local_s;
 
diff --git a/sm/keylist.c b/sm/keylist.c
index 4f2d009fd..2d51aa74d 100644
--- a/sm/keylist.c
+++ b/sm/keylist.c
@@ -251,9 +251,11 @@ print_capabilities (ksba_cert_t cert, estream_t fp)
 {
   gpg_error_t err;
   unsigned int use;
+  unsigned int is_encr, is_sign, is_cert;
   size_t buflen;
   char buffer[1];
 
+
   err = ksba_cert_get_user_data (cert, "is_qualified",
                                  &buffer, sizeof (buffer), &buflen);
   if (!err && buflen)
@@ -285,17 +287,33 @@ print_capabilities (ksba_cert_t cert, estream_t fp)
       return;
     }
 
+  is_encr = is_sign = is_cert = 0;
+
   if ((use & (KSBA_KEYUSAGE_KEY_ENCIPHERMENT|KSBA_KEYUSAGE_DATA_ENCIPHERMENT)))
-    es_putc ('e', fp);
+    is_encr = 1;
   if ((use & (KSBA_KEYUSAGE_DIGITAL_SIGNATURE|KSBA_KEYUSAGE_NON_REPUDIATION)))
-    es_putc ('s', fp);
+    is_sign = 1;
   if ((use & KSBA_KEYUSAGE_KEY_CERT_SIGN))
+    is_cert = 1;
+
+  /* We need to returned the faked key usage to frontends so that they
+   * can select the right key.  Note that we don't do this for the
+   * human readable keyUsage.  */
+  if ((opt.compat_flags & COMPAT_ALLOW_KA_TO_ENCR)
+      && (use & KSBA_KEYUSAGE_KEY_AGREEMENT))
+    is_encr = 1;
+
+  if (is_encr)
+    es_putc ('e', fp);
+  if (is_sign)
+    es_putc ('s', fp);
+  if (is_cert)
     es_putc ('c', fp);
-  if ((use & (KSBA_KEYUSAGE_KEY_ENCIPHERMENT|KSBA_KEYUSAGE_DATA_ENCIPHERMENT)))
+  if (is_encr)
     es_putc ('E', fp);
-  if ((use & (KSBA_KEYUSAGE_DIGITAL_SIGNATURE|KSBA_KEYUSAGE_NON_REPUDIATION)))
+  if (is_sign)
     es_putc ('S', fp);
-  if ((use & KSBA_KEYUSAGE_KEY_CERT_SIGN))
+  if (is_cert)
     es_putc ('C', fp);
 }