DKIM: verify using separate pool-pair, reset per message

[users/heiko/exim.git] / src / src / dkim.c

diff --git a/src/src/dkim.c b/src/src/dkim.c
index 5c9d2279e165767715385013862a330b81023c9d..a48f1a17af47e42b309e38118484ccee53f2f247 100644 (file)
--- a/src/src/dkim.c
+++ b/src/src/dkim.c
@@ -3,6 +3,7 @@
 *************************************************/
 
 /* Copyright (c) University of Cambridge, 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 /* Code for DKIM support. Other DKIM relevant code is in
@@ -21,6 +22,7 @@ void
 params_dkim(void)
 {
 builtin_macro_create_var(US"_DKIM_SIGN_HEADERS", US PDKIM_DEFAULT_SIGN_HEADERS);
+builtin_macro_create_var(US"_DKIM_OVERSIGN_HEADERS", US PDKIM_OVERSIGN_HEADERS);
 }
 # else /*!MACRO_PREDEF*/
 
@@ -107,12 +109,15 @@ dkim_exim_verify_init(BOOL dot_stuffing)
 {
 dkim_exim_init();
 
-/* There is a store-reset between header & body reception
-so cannot use the main pool. Any allocs done by Exim
-memory-handling must use the perm pool. */
+/* There is a store-reset between header & body reception for the main pool
+(actually, after every header line) so cannot use that as we need the data we
+store per-header, during header processing, at the end of body reception
+for evaluating the signature.  Any allocs done for dkim verify
+memory-handling must use a different pool.  We use a separate one that we
+can reset per message. */
 
 dkim_verify_oldpool = store_pool;
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
 
 /* Free previous context if there is one */
 
@@ -137,7 +142,7 @@ dkim_exim_verify_feed(uschar * data, int len)
 {
 int rc;
 
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
 if (  dkim_collect_input
    && (rc = pdkim_feed(dkim_verify_ctx, data, len)) != PDKIM_OK)
   {
@@ -267,6 +272,11 @@ else
                "(headers probably modified in transit)]");
          break;
 
+       case PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE:
+         logmsg = string_cat(logmsg,
+               US"signature invalid (key too short)]");
+         break;
+
        default:
          logmsg = string_cat(logmsg, US"unspecified reason]");
        }
@@ -298,7 +308,7 @@ int rc;
 gstring * g = NULL;
 const uschar * errstr = NULL;
 
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
 
 /* Delete eventual previous signature chain */
 
@@ -405,7 +415,7 @@ for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
     dkim_cur_sig = sig;
     dkim_signing_domain = US sig->domain;
     dkim_signing_selector = US sig->selector;
-    dkim_key_length = sig->sighash.len * 8;
+    dkim_key_length = sig->keybits;
 
     /* These two return static strings, so we can compare the addr
     later to see if the ACL overwrote them.  Check that when logging */
@@ -559,6 +569,7 @@ switch (what)
                                                return US"pubkey_unavailable";
       case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:return US"pubkey_dns_syntax";
       case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return US"pubkey_der_syntax";
+      case PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE:        return US"pubkey_too_short";
       case PDKIM_VERIFY_FAIL_BODY:             return US"bodyhash_mismatch";
       case PDKIM_VERIFY_FAIL_MESSAGE:          return US"signature_incorrect";
       }
@@ -853,6 +864,9 @@ for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
           g = string_cat(g,
            US"fail (signature did not verify; headers probably modified in transit)\n\t\t");
          break;
+        case PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE:      /* should this really be "polcy"? */
+          g = string_fmt_append(g, "fail (public key too short: %u bits)\n\t\t", sig->keybits);
+          break;
         default:
           g = string_cat(g, US"fail (unspecified reason)\n\t\t");
          break;