X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/1e1ddfac79fbcd052f199500a6493c7f79cb8462..c6a290f4d8df3734b3cdc2232b4334ff8386c1da:/src/src/dkim.c

diff --git a/src/src/dkim.c b/src/src/dkim.c
index 92adb3589..0c5e84788 100644
--- a/src/src/dkim.c
+++ b/src/src/dkim.c
@@ -3,7 +3,7 @@
 *************************************************/
 
 /* Copyright (c) University of Cambridge, 1995 - 2018 */
-/* Copyright (c) The Exim Maintainers 2020 */
+/* Copyright (c) The Exim Maintainers 2020 - 2021*/
 /* See the file NOTICE for conditions of use and distribution. */
 
 /* Code for DKIM support. Other DKIM relevant code is in
@@ -50,11 +50,11 @@ dkim_exim_query_dns_txt(const uschar * name)
 dns_answer * dnsa = store_get_dns_answer();
 dns_scan dnss;
 rmark reset_point = store_mark();
-gstring * g = NULL;
+gstring * g = string_get_tainted(256, TRUE);
 
 lookup_dnssec_authenticated = NULL;
 if (dns_lookup(dnsa, name, T_TXT, NULL) != DNS_SUCCEED)
-  return NULL;	/*XXX better error detail?  logging? */
+  goto bad;
 
 /* Search for TXT record */
 
@@ -62,12 +62,8 @@ for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
      rr;
      rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
   if (rr->type == T_TXT)
-    {
-    int rr_offset = 0;
-
-    /* Copy record content to the answer buffer */
-
-    while (rr_offset < rr->size)
+    {			/* Copy record content to the answer buffer */
+    for (int rr_offset = 0; rr_offset < rr->size; )
       {
       uschar len = rr->data[rr_offset++];
 
@@ -78,18 +74,20 @@ for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
       rr_offset += len;
       }
 
-    /* check if this looks like a DKIM record */
+    /* Check if this looks like a DKIM record */
     if (Ustrncmp(g->s, "v=", 2) != 0 || strncasecmp(CS g->s, "v=dkim", 6) == 0)
       {
+      store_free_dns_answer(dnsa);
       gstring_release_unused(g);
       return string_from_gstring(g);
       }
 
-    if (g) g->ptr = 0;		/* overwrite previous record */
+    g->ptr = 0;		/* overwrite previous record */
     }
 
 bad:
 store_reset(reset_point);
+store_free_dns_answer(dnsa);
 return NULL;	/*XXX better error detail?  logging? */
 }
 
@@ -109,12 +107,15 @@ 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 */
 
@@ -127,19 +128,22 @@ dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt, dot_stuffing);
 dkim_collect_input = dkim_verify_ctx ? DKIM_MAX_SIGNATURES : 0;
 dkim_collect_error = NULL;
 
-/* Start feed up with any cached data */
-receive_get_cache();
+/* Start feed up with any cached data, but limited to message data */
+receive_get_cache(chunking_state == CHUNKING_LAST
+		  ? chunking_data_left : GETC_BUFFER_UNLIMITED);
 
 store_pool = dkim_verify_oldpool;
 }
 
 
+/* Submit a chunk of data for verification input.
+Only use the data when the feed is activated. */
 void
 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)
   {
@@ -305,7 +309,7 @@ int rc;
 gstring * g = NULL;
 const uschar * errstr = NULL;
 
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
 
 /* Delete eventual previous signature chain */