* Exim - an Internet mail transport agent *
*************************************************/
+/* Copyright (c) The Exim Maintainers 2020 - 2024 */
/* Copyright (c) University of Cambridge, 1995 - 2018 */
/* See the file NOTICE for conditions of use and distribution. */
+/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Code for DKIM support. Other DKIM relevant code is in
receive.c, transport.c and transports/smtp.c */
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*/
-/*XXX the caller only uses the first record if we return multiple.
+/* Look up the DKIM record in DNS for the given hostname.
+Will use the first found if there are multiple.
+The return string is tainted, having come from off-site.
*/
uschar *
-dkim_exim_query_dns_txt(uschar * name)
+dkim_exim_query_dns_txt(const uschar * name)
{
-dns_answer dnsa;
+dns_answer * dnsa = store_get_dns_answer();
dns_scan dnss;
-dns_record *rr;
-gstring * g = NULL;
+rmark reset_point = store_mark();
+gstring * g = string_get_tainted(256, GET_TAINTED);
lookup_dnssec_authenticated = NULL;
-if (dns_lookup(&dnsa, name, T_TXT, NULL) != DNS_SUCCEED)
- return NULL; /*XXX better error detail? logging? */
+if (dns_lookup(dnsa, name, T_TXT, NULL) != DNS_SUCCEED)
+ goto bad;
/* Search for TXT record */
-for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
+for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
rr;
- rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
+ 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++];
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)
{
- gstring_reset_unused(g);
+ store_free_dns_answer(dnsa);
+ gstring_release_unused(g);
return string_from_gstring(g);
}
- if (g) g->ptr = 0; /* overwrite previous record */
+ gstring_reset(g); /* overwrite previous record */
}
bad:
-if (g) store_reset(g);
+store_reset(reset_point);
+store_free_dns_answer(dnsa);
return NULL; /*XXX better error detail? logging? */
}
void
dkim_exim_init(void)
{
+if (f.dkim_init_done) return;
+f.dkim_init_done = TRUE;
pdkim_init();
}
void
dkim_exim_verify_init(BOOL dot_stuffing)
{
-/* 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. */
+dkim_exim_init();
+
+/* 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 */
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)
{
logmsg = string_append(logmsg, 2, "d=", s);
if (!(s = sig->selector)) s = US"<UNSET>";
logmsg = string_append(logmsg, 2, " s=", s);
-logmsg = string_append(logmsg, 7,
- " c=", sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
- "/", sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
- " a=", dkim_sig_to_a_tag(sig),
-string_sprintf(" b=" SIZE_T_FMT,
- (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : 0));
+logmsg = string_fmt_append(logmsg, " c=%s/%s a=%s b=" SIZE_T_FMT,
+ sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
+ sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
+ dkim_sig_to_a_tag(sig),
+ (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : (size_t)0);
if ((s= sig->identity)) logmsg = string_append(logmsg, 2, " i=", s);
-if (sig->created > 0) logmsg = string_cat(logmsg,
- string_sprintf(" t=%lu", sig->created));
-if (sig->expires > 0) logmsg = string_cat(logmsg,
- string_sprintf(" x=%lu", sig->expires));
-if (sig->bodylength > -1) logmsg = string_cat(logmsg,
- string_sprintf(" l=%lu", sig->bodylength));
+if (sig->created > 0) logmsg = string_fmt_append(logmsg, " t=%lu",
+ sig->created);
+if (sig->expires > 0) logmsg = string_fmt_append(logmsg, " x=%lu",
+ sig->expires);
+if (sig->bodylength > -1) logmsg = string_fmt_append(logmsg, " l=%lu",
+ sig->bodylength);
if (sig->verify_status & PDKIM_VERIFY_POLICY)
logmsg = string_append(logmsg, 5,
"(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]");
}
break;
}
-log_write(0, LOG_MAIN, "%s", string_from_gstring(logmsg));
+log_write(0, LOG_MAIN, "%Y", logmsg);
return;
}
void
dkim_exim_verify_log_all(void)
{
-pdkim_signature * sig;
-for (sig = dkim_signatures; sig; sig = sig->next) dkim_exim_verify_log_sig(sig);
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
+ dkim_exim_verify_log_sig(sig);
}
void
dkim_exim_verify_finish(void)
{
-pdkim_signature * sig;
int rc;
gstring * g = NULL;
const uschar * errstr = NULL;
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
/* Delete eventual previous signature chain */
log_write(0, LOG_MAIN,
"DKIM: Error during validation, disabling signature verification: %.100s",
dkim_collect_error);
- dkim_disable_verify = TRUE;
+ f.dkim_disable_verify = TRUE;
goto out;
}
/* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */
-for (sig = dkim_signatures; sig; sig = sig->next)
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
{
if (sig->domain) g = string_append_listele(g, ':', sig->domain);
if (sig->identity) g = string_append_listele(g, ':', sig->identity);
}
-
-if (g) dkim_signers = g->s;
+gstring_release_unused(g);
+dkim_signers = string_from_gstring(g);
out:
store_pool = dkim_verify_oldpool;
{
int rc;
DEBUG(D_receive)
- debug_printf("calling acl_smtp_dkim for dkim_cur_signer='%s'\n", id);
+ debug_printf("calling acl_smtp_dkim for identity '%s' domain '%s' sel '%s'\n",
+ id, dkim_signing_domain, dkim_signing_selector);
rc = acl_check(ACL_WHERE_DKIM, NULL, acl_smtp_dkim, user_msgptr, log_msgptr);
dkim_exim_verify_log_sig(dkim_cur_sig);
/* For the given identity, run the DKIM ACL once for each matching signature.
+If none match, run it once.
Arguments
id Identity to look for in dkim signatures
dkim_exim_acl_run(uschar * id, gstring ** res_ptr,
uschar ** user_msgptr, uschar ** log_msgptr)
{
-pdkim_signature * sig;
uschar * cmp_val;
int rc = -1;
dkim_verify_reason = US"";
dkim_cur_signer = id;
-if (dkim_disable_verify || !id || !dkim_verify_ctx)
+if (f.dkim_disable_verify || !id || !dkim_verify_ctx)
return OK;
/* Find signatures to run ACL on */
-for (sig = dkim_signatures; sig; sig = sig->next)
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
if ( (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain)
&& strcmpic(cmp_val, id) == 0
)
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 */
dkim_verify_status = dkim_exim_expand_query(DKIM_VERIFY_STATUS);
dkim_verify_reason = dkim_exim_expand_query(DKIM_VERIFY_REASON);
- if ((rc = dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr)) != OK)
+ if ( (rc = dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr)) != OK
+ || dkim_verify_minimal && Ustrcmp(dkim_verify_status, "pass") == 0)
return rc;
}
uschar *
dkim_exim_expand_query(int what)
{
-if (!dkim_verify_ctx || dkim_disable_verify || !dkim_cur_sig)
+if (!dkim_verify_ctx || f.dkim_disable_verify || !dkim_cur_sig)
return dkim_exim_expand_defaults(what);
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";
}
dkim_exim_sign_init(void)
{
int old_pool = store_pool;
+
+dkim_exim_init();
store_pool = POOL_MAIN;
pdkim_init_context(&dkim_sign_ctx, FALSE, &dkim_exim_query_dns_txt);
store_pool = old_pool;
store_pool = POOL_MAIN;
+GET_OPTION("dkim_domain");
if ((s = dkim->dkim_domain) && !(dkim_domain = expand_cstring(s)))
/* expansion error, do not send message. */
{ errwhen = US"dkim_domain"; goto expand_bad; }
/* Only sign once for each domain, no matter how often it
appears in the expanded list. */
+ dkim_signing_domain = string_copylc(dkim_signing_domain);
if (match_isinlist(dkim_signing_domain, CUSS &seen_doms,
0, NULL, NULL, MCL_STRING, TRUE, NULL) == OK)
continue;
/* Set $dkim_selector expansion variable to each selector in list,
for this domain. */
+ GET_OPTION("dkim_selector");
if (!(dkim_sel = expand_string(dkim->dkim_selector)))
{ errwhen = US"dkim_selector"; goto expand_bad; }
/* Get canonicalization to use */
+ GET_OPTION("dkim_canon");
dkim_canon_expanded = dkim->dkim_canon
? expand_string(dkim->dkim_canon) : US"relaxed";
if (!dkim_canon_expanded) /* expansion error, do not send message. */
pdkim_canon = PDKIM_CANON_RELAXED;
}
+ GET_OPTION("dkim_sign_headers");
if ( dkim->dkim_sign_headers
&& !(dkim_sign_headers_expanded = expand_string(dkim->dkim_sign_headers)))
{ errwhen = US"dkim_sign_header"; goto expand_bad; }
/* Get private key to use. */
+ GET_OPTION("dkim_private_key");
if (!(dkim_private_key_expanded = expand_string(dkim->dkim_private_key)))
{ errwhen = US"dkim_private_key"; goto expand_bad; }
expand_file_big_buffer(dkim_private_key_expanded)))
goto bad;
+ GET_OPTION("dkim_hash");
if (!(dkim_hash_expanded = expand_string(dkim->dkim_hash)))
{ errwhen = US"dkim_hash"; goto expand_bad; }
+ GET_OPTION("dkim_identity");
if (dkim->dkim_identity)
if (!(dkim_identity_expanded = expand_string(dkim->dkim_identity)))
{ errwhen = US"dkim_identity"; goto expand_bad; }
else if (!*dkim_identity_expanded)
dkim_identity_expanded = NULL;
+ GET_OPTION("dkim_timestamps");
if (dkim->dkim_timestamps)
if (!(dkim_timestamps_expanded = expand_string(dkim->dkim_timestamps)))
{ errwhen = US"dkim_timestamps"; goto expand_bad; }
else
- xval = (tval = (unsigned long) time(NULL))
- + strtoul(CCS dkim_timestamps_expanded, NULL, 10);
+ {
+ tval = (unsigned long) time(NULL);
+ xval = strtoul(CCS dkim_timestamps_expanded, NULL, 10);
+ if (xval > 0)
+ xval += tval;
+ }
if (!(sig = pdkim_init_sign(&dkim_sign_ctx, dkim_signing_domain,
dkim_signing_selector,
if (!pdkim_set_sig_bodyhash(&dkim_sign_ctx, sig))
goto bad;
+ dkim_signing_record = string_append_listele(dkim_signing_record, ':', dkim_signing_domain);
+ dkim_signing_record = string_append_listele(dkim_signing_record, ':', dkim_signing_selector);
+
if (!dkim_sign_ctx.sig) /* link sig to context chain */
dkim_sign_ctx.sig = sig;
else
pk_bad:
log_write(0, LOG_MAIN|LOG_PANIC,
- "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc));
+ "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc));
bad:
sigbuf = NULL;
goto CLEANUP;
expand_bad:
- log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand %s: %s",
- errwhen, expand_string_message);
+ *errstr = string_sprintf("failed to expand %s: %s",
+ errwhen, expand_string_message);
+ log_write(0, LOG_MAIN | LOG_PANIC, "%s", *errstr);
goto bad;
}
gstring *
authres_dkim(gstring * g)
{
-pdkim_signature * sig;
int start = 0; /* compiler quietening */
-DEBUG(D_acl) start = g->ptr;
+DEBUG(D_acl) start = gstring_length(g);
-for (sig = dkim_signatures; sig; sig = sig->next)
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
{
g = string_catn(g, US";\n\tdkim=", 8);
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;
}
DEBUG(D_acl)
- if (g->ptr == start)
- debug_printf("DKIM: no authres\n");
+ if (gstring_length(g) == start)
+ debug_printf("DKIM:\tno authres\n");
else
- debug_printf("DKIM: authres '%.*s'\n", g->ptr - start - 3, g->s + start + 3);
+ debug_printf("DKIM:\tauthres '%.*s'\n", g->ptr - start - 3, g->s + start + 3);
return g;
}
git://git.exim.org / exim.git / blobdiff