common,gpg,sm: Restrict the use of algorithms according to CO_DE_VS.

* common/compliance.c (gnupg_pk_is_allowed): New function.
(gnupg_cipher_is_allowed): Likewise.
(gnupg_digest_is_allowed): Likewise.
* common/compliance.h (enum pk_use_case): New definition.
(gnupg_pk_is_allowed): New prototype.
(gnupg_cipher_is_allowed): Likewise.
(gnupg_digest_is_allowed): Likewise.
* g10/decrypt-data.c (decrypt_data): Restrict use of algorithms using
the new predicates.
* g10/encrypt.c (encrypt_crypt): Likewise.
* g10/gpg.c (main): Likewise.
* g10/pubkey-enc.c (get_session_key): Likewise.
* g10/sig-check.c (check_signature2): Likewise.
* g10/sign.c (do_sign): Likewise.
* sm/decrypt.c (gpgsm_decrypt): Likewise.
* sm/encrypt.c (gpgsm_encrypt): Likewise.
* sm/gpgsm.c (main): Likewise.
* sm/sign.c (gpgsm_sign): Likewise.
* sm/verify.c (gpgsm_verify): Likewise.
--

With this change, policies can effectively restrict what algorithms
are used for different purposes.  The algorithm policy for CO_DE_VS is
implemented.

GnuPG-bug-id: 3191
Signed-off-by: Justus Winter <justus@g10code.com>

5 files changed, 155 insertions, 20 deletions

diff --git a/sm/decrypt.c b/sm/decrypt.c
index a36f69027..6909b157f 100644
--- a/sm/decrypt.c
+++ b/sm/decrypt.c
@@ -358,6 +358,17 @@ gpgsm_decrypt (ctrl_t ctrl, int in_fd, estream_t out_fp)
               goto leave;
             }
 
+          /* Check compliance.  */
+          if (! gnupg_cipher_is_allowed (opt.compliance, 0, algo, mode))
+            {
+              log_error (_ ("you may not use cipher algorithm '%s'"
+                            " while in %s mode\n"),
+                         gcry_cipher_algo_name (algo),
+                         gnupg_compliance_option_string (opt.compliance));
+              rc = gpg_error (GPG_ERR_CIPHER_ALGO);
+              goto leave;
+            }
+
           /* For CMS, CO_DE_VS demands CBC mode.  */
           is_de_vs = gnupg_cipher_is_compliant (CO_DE_VS, algo, mode);
 
@@ -465,15 +476,27 @@ gpgsm_decrypt (ctrl_t ctrl, int in_fd, estream_t out_fp)
                   hexkeygrip = gpgsm_get_keygrip_hexstring (cert);
                   desc = gpgsm_format_keydesc (cert);
 
-                  /* Check that all certs are compliant with CO_DE_VS.  */
-                  if (is_de_vs)
-                    {
-                      unsigned int nbits;
-                      int pk_algo = gpgsm_get_key_algo_info (cert, &nbits);
-
-                      is_de_vs = gnupg_pk_is_compliant (CO_DE_VS, pk_algo, NULL,
-                                                        nbits, NULL);
-                    }
+                  {
+                    unsigned int nbits;
+                    int pk_algo = gpgsm_get_key_algo_info (cert, &nbits);
+
+                    /* Check compliance.  */
+                    if (! gnupg_pk_is_allowed (opt.compliance, PK_USE_DECRYPTION,
+                                               pk_algo, NULL, nbits, NULL))
+                      {
+                        log_error ("certificate ID 0x%08lX not suitable for "
+                                   "decryption while in %s mode\n",
+                                   gpgsm_get_short_fingerprint (cert, NULL),
+                                   gnupg_compliance_option_string (opt.compliance));
+                        rc = gpg_error (GPG_ERR_PUBKEY_ALGO);
+                        goto oops;
+                      }
+
+                    /* Check that all certs are compliant with CO_DE_VS.  */
+                    is_de_vs = (is_de_vs
+                                && gnupg_pk_is_compliant (CO_DE_VS, pk_algo, NULL,
+                                                          nbits, NULL));
+                  }
 
                 oops:
                   if (rc)
diff --git a/sm/encrypt.c b/sm/encrypt.c
index c43a9e6a4..45860a89f 100644
--- a/sm/encrypt.c
+++ b/sm/encrypt.c
@@ -33,6 +33,7 @@
 
 #include "keydb.h"
 #include "../common/i18n.h"
+#include "../common/compliance.h"
 
 
 struct dek_s {
@@ -405,6 +406,19 @@ gpgsm_encrypt (ctrl_t ctrl, certlist_t recplist, int data_fd, estream_t out_fp)
       goto leave;
     }
 
+  /* Check compliance.  */
+  if (! gnupg_cipher_is_allowed (opt.compliance, 1,
+                                 gcry_cipher_map_name (opt.def_cipher_algoid),
+                                 gcry_cipher_mode_from_oid (opt.def_cipher_algoid)))
+    {
+      log_error (_ ("you may not use cipher algorithm '%s'"
+		    " while in %s mode\n"),
+		 opt.def_cipher_algoid,
+		 gnupg_compliance_option_string (opt.compliance));
+      rc = gpg_error (GPG_ERR_CIPHER_ALGO);
+      goto leave;
+    }
+
   /* Create a session key */
   dek = xtrycalloc_secure (1, sizeof *dek);
   if (!dek)
@@ -448,6 +462,20 @@ gpgsm_encrypt (ctrl_t ctrl, certlist_t recplist, int data_fd, estream_t out_fp)
     {
       unsigned char *encval;
 
+      /* Check compliance.  */
+      unsigned int nbits;
+      int pk_algo = gpgsm_get_key_algo_info (cl->cert, &nbits);
+      if (! gnupg_pk_is_allowed (opt.compliance, PK_USE_ENCRYPTION, pk_algo,
+                                 NULL, nbits, NULL))
+        {
+          log_error ("certificate ID 0x%08lX not suitable for "
+                     "encryption while in %s mode\n",
+                     gpgsm_get_short_fingerprint (cl->cert, NULL),
+                     gnupg_compliance_option_string (opt.compliance));
+          rc = gpg_error (GPG_ERR_PUBKEY_ALGO);
+          goto leave;
+        }
+
       rc = encrypt_dek (dek, cl->cert, &encval);
       if (rc)
         {
diff --git a/sm/gpgsm.c b/sm/gpgsm.c
index f749cfd28..c462544e2 100644
--- a/sm/gpgsm.c
+++ b/sm/gpgsm.c
@@ -1614,6 +1614,43 @@ main ( int argc, char **argv)
         }
     }
 
+  /* Check our chosen algorithms against the list of allowed
+   * algorithms in the current compliance mode, and fail hard if it is
+   * not.  This is us being nice to the user informing her early that
+   * the chosen algorithms are not available.  We also check and
+   * enforce this right before the actual operation.  */
+  if (! gnupg_cipher_is_allowed (opt.compliance,
+                                 cmd == aEncr || cmd == aSignEncr,
+                                 gcry_cipher_map_name (opt.def_cipher_algoid),
+                                 GCRY_CIPHER_MODE_NONE)
+      && ! gnupg_cipher_is_allowed (opt.compliance,
+                                    cmd == aEncr || cmd == aSignEncr,
+                                    gcry_cipher_mode_from_oid (opt.def_cipher_algoid),
+                                    GCRY_CIPHER_MODE_NONE))
+    log_error (_ ("you may not use cipher algorithm '%s'"
+                  " while in %s mode\n"),
+               opt.def_cipher_algoid, gnupg_compliance_option_string (opt.compliance));
+
+  if (forced_digest_algo
+      && ! gnupg_digest_is_allowed (opt.compliance,
+                                     cmd == aSign
+                                     || cmd == aSignEncr
+                                     || cmd == aClearsign,
+                                     opt.forced_digest_algo))
+    log_error (_ ("you may not use digest algorithm '%s'"
+                  " while in %s mode\n"),
+               forced_digest_algo, gnupg_compliance_option_string (opt.compliance));
+
+  if (extra_digest_algo
+      && ! gnupg_digest_is_allowed (opt.compliance,
+                                     cmd == aSign
+                                     || cmd == aSignEncr
+                                     || cmd == aClearsign,
+                                     opt.extra_digest_algo))
+    log_error (_ ("you may not use digest algorithm '%s'"
+                  " while in %s mode\n"),
+               forced_digest_algo, gnupg_compliance_option_string (opt.compliance));
+
   if (log_get_errorcount(0))
     gpgsm_exit(2);
 
diff --git a/sm/sign.c b/sm/sign.c
index e65562d54..2fbee7516 100644
--- a/sm/sign.c
+++ b/sm/sign.c
@@ -460,6 +460,33 @@ gpgsm_sign (ctrl_t ctrl, certlist_t signerlist,
           break;
         }
       cl->hash_algo_oid = oid;
+
+      /* Check compliance.  */
+      if (! gnupg_digest_is_allowed (opt.compliance, 1, cl->hash_algo))
+        {
+          log_error (_ ("you may not use digest algorithm '%s'"
+                        " while in %s mode\n"),
+                     gcry_md_algo_name (cl->hash_algo),
+                     gnupg_compliance_option_string (opt.compliance));
+          err = gpg_error (GPG_ERR_DIGEST_ALGO);
+          goto leave;
+        }
+
+      {
+        unsigned int nbits;
+        int pk_algo = gpgsm_get_key_algo_info (cl->cert, &nbits);
+
+        if (! gnupg_pk_is_allowed (opt.compliance, PK_USE_SIGNING, pk_algo,
+                                   NULL, nbits, NULL))
+          {
+            log_error ("certificate ID 0x%08lX not suitable for "
+                       "signing while in %s mode\n",
+                       gpgsm_get_short_fingerprint (cl->cert, NULL),
+                       gnupg_compliance_option_string (opt.compliance));
+            err = gpg_error (GPG_ERR_PUBKEY_ALGO);
+            goto leave;
+          }
+      }
     }
 
   if (opt.verbose)
diff --git a/sm/verify.c b/sm/verify.c
index e19c04e38..89f06efee 100644
--- a/sm/verify.c
+++ b/sm/verify.c
@@ -450,6 +450,37 @@ gpgsm_verify (ctrl_t ctrl, int in_fd, int data_fd, estream_t out_fp)
           goto next_signer;
         }
 
+      /* Check compliance.  */
+      {
+        unsigned int nbits;
+        int pk_algo = gpgsm_get_key_algo_info (cert, &nbits);
+
+        if (! gnupg_pk_is_allowed (opt.compliance, PK_USE_VERIFICATION,
+                                   pk_algo, NULL, nbits, NULL))
+          {
+            log_error ("certificate ID 0x%08lX not suitable for "
+                       "verification while in %s mode\n",
+                       gpgsm_get_short_fingerprint (cert, NULL),
+                       gnupg_compliance_option_string (opt.compliance));
+            goto next_signer;
+          }
+
+        if (! gnupg_digest_is_allowed (opt.compliance, 0, sigval_hash_algo))
+          {
+            log_error (_ ("you may not use digest algorithm '%s'"
+                          " while in %s mode\n"),
+                       gcry_md_algo_name (sigval_hash_algo),
+                       gnupg_compliance_option_string (opt.compliance));
+            goto next_signer;
+          }
+
+        /* Check compliance with CO_DE_VS.  */
+        if (gnupg_pk_is_compliant (CO_DE_VS, pk_algo, NULL, nbits, NULL)
+            && gnupg_digest_is_compliant (CO_DE_VS, sigval_hash_algo))
+          gpgsm_status (ctrl, STATUS_VERIFICATION_COMPLIANCE_MODE,
+                        gnupg_status_compliance_flag (CO_DE_VS));
+      }
+
       log_info (_("Signature made "));
       if (*sigtime)
         dump_isotime (sigtime);
@@ -632,17 +663,6 @@ gpgsm_verify (ctrl_t ctrl, int in_fd, int data_fd, estream_t out_fp)
                     (verifyflags & VALIDATE_FLAG_CHAIN_MODEL)?
                     "0 chain": "0 shell");
 
-      /* Check compliance with CO_DE_VS.  */
-      {
-        unsigned int nbits;
-        int pk_algo = gpgsm_get_key_algo_info (cert, &nbits);
-
-        if (gnupg_pk_is_compliant (CO_DE_VS, pk_algo, NULL, nbits, NULL)
-            && gnupg_digest_is_compliant (CO_DE_VS, sigval_hash_algo))
-          gpgsm_status (ctrl, STATUS_VERIFICATION_COMPLIANCE_MODE,
-                        gnupg_status_compliance_flag (CO_DE_VS));
-      }
-
     next_signer:
       rc = 0;
       xfree (issuer);