* Exim - an Internet mail transport agent *
*************************************************/
-/* Copyright (c) University of Cambridge, 1995 - 2016 */
+/* 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 */
#ifndef DISABLE_DKIM
-#include "pdkim/pdkim.h"
+# include "pdkim/pdkim.h"
+
+# ifdef MACRO_PREDEF
+# include "macro_predef.h"
+
+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*/
+
+
+
+pdkim_ctx dkim_sign_ctx;
int dkim_verify_oldpool;
pdkim_ctx *dkim_verify_ctx = NULL;
-pdkim_signature *dkim_signatures = NULL;
pdkim_signature *dkim_cur_sig = NULL;
+static const uschar * dkim_collect_error = NULL;
-static int
-dkim_exim_query_dns_txt(char *name, char *answer)
+#define DKIM_MAX_SIGNATURES 20
+
+
+
+/* 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(const uschar * name)
{
-dns_answer dnsa;
+dns_answer * dnsa = store_get_dns_answer();
dns_scan dnss;
-dns_record *rr;
+rmark reset_point = store_mark();
+gstring * g = string_get_tainted(256, GET_TAINTED);
lookup_dnssec_authenticated = NULL;
-if (dns_lookup(&dnsa, US name, T_TXT, NULL) != DNS_SUCCEED)
- return PDKIM_FAIL;
+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;
- int answer_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++];
- snprintf(answer + answer_offset,
- PDKIM_DNS_TXT_MAX_RECLEN - answer_offset,
- "%.*s", (int)len, (char *) (rr->data + rr_offset));
+
+ g = string_catn(g, US(rr->data + rr_offset), len);
+ if (g->ptr >= PDKIM_DNS_TXT_MAX_RECLEN)
+ goto bad;
+
rr_offset += len;
- answer_offset += len;
- if (answer_offset >= PDKIM_DNS_TXT_MAX_RECLEN)
- return PDKIM_FAIL;
}
- return PDKIM_OK;
+
+ /* 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);
+ }
+
+ gstring_reset(g); /* overwrite previous record */
}
-return PDKIM_FAIL;
+bad:
+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(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 */
/* Create new context */
-dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt);
-dkim_collect_input = !!dkim_verify_ctx;
+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, 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)
{
-store_pool = POOL_PERM;
+int rc;
+
+store_pool = POOL_MESSAGE;
if ( dkim_collect_input
- && pdkim_feed(dkim_verify_ctx, (char *)data, len) != PDKIM_OK)
- dkim_collect_input = FALSE;
+ && (rc = pdkim_feed(dkim_verify_ctx, data, len)) != PDKIM_OK)
+ {
+ dkim_collect_error = pdkim_errstr(rc);
+ log_write(0, LOG_MAIN,
+ "DKIM: validation error: %.100s", dkim_collect_error);
+ dkim_collect_input = 0;
+ }
store_pool = dkim_verify_oldpool;
}
-void
-dkim_exim_verify_finish(void)
+/* Log the result for the given signature */
+static void
+dkim_exim_verify_log_sig(pdkim_signature * sig)
{
-pdkim_signature *sig = NULL;
-int dkim_signers_size = 0;
-int dkim_signers_ptr = 0;
-dkim_signers = NULL;
-
-store_pool = POOL_PERM;
-
-/* Delete eventual previous signature chain */
-
-dkim_signatures = NULL;
-
-/* If we have arrived here with dkim_collect_input == FALSE, it
-means there was a processing error somewhere along the way.
-Log the incident and disable futher verification. */
-
-if (!dkim_collect_input)
- {
- log_write(0, LOG_MAIN,
- "DKIM: Error while running this message through validation,"
- " disabling signature verification.");
- dkim_disable_verify = TRUE;
- goto out;
+gstring * logmsg;
+uschar * s;
+
+if (!sig) return;
+
+/* Remember the domain for the first pass result */
+
+if ( !dkim_verify_overall
+ && dkim_verify_status
+ ? Ustrcmp(dkim_verify_status, US"pass") == 0
+ : sig->verify_status == PDKIM_VERIFY_PASS
+ )
+ dkim_verify_overall = string_copy(sig->domain);
+
+/* Rewrite the sig result if the ACL overrode it. This is only
+needed because the DMARC code (sigh) peeks at the dkim sigs.
+Mark the sig for this having been done. */
+
+if ( dkim_verify_status
+ && ( dkim_verify_status != dkim_exim_expand_query(DKIM_VERIFY_STATUS)
+ || dkim_verify_reason != dkim_exim_expand_query(DKIM_VERIFY_REASON)
+ ) )
+ { /* overridden by ACL */
+ sig->verify_ext_status = -1;
+ if (Ustrcmp(dkim_verify_status, US"fail") == 0)
+ sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_FAIL;
+ else if (Ustrcmp(dkim_verify_status, US"invalid") == 0)
+ sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_INVALID;
+ else if (Ustrcmp(dkim_verify_status, US"none") == 0)
+ sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_NONE;
+ else if (Ustrcmp(dkim_verify_status, US"pass") == 0)
+ sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_PASS;
+ else
+ sig->verify_status = -1;
}
-dkim_collect_input = FALSE;
-
-/* Finish DKIM operation and fetch link to signatures chain */
-
-if (pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures) != PDKIM_OK)
- goto out;
-
-for (sig = dkim_signatures; sig; sig = sig->next)
- {
- int size = 0;
- int ptr = 0;
-
- /* Log a line for each signature */
-
- uschar *logmsg = string_append(NULL, &size, &ptr, 5,
- string_sprintf("d=%s s=%s c=%s/%s a=%s b=%d ",
- sig->domain,
- sig->selector,
- sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
- sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
- sig->algo == PDKIM_ALGO_RSA_SHA256 ? "rsa-sha256" : "rsa-sha1",
- sig->sigdata.len * 8
- ),
-
- sig->identity ? string_sprintf("i=%s ", sig->identity) : US"",
- sig->created > 0 ? string_sprintf("t=%lu ", sig->created) : US"",
- sig->expires > 0 ? string_sprintf("x=%lu ", sig->expires) : US"",
- sig->bodylength > -1 ? string_sprintf("l=%lu ", sig->bodylength) : US""
- );
-
+if (!LOGGING(dkim_verbose)) return;
+
+
+logmsg = string_catn(NULL, US"DKIM: ", 6);
+if (!(s = sig->domain)) s = US"<UNSET>";
+logmsg = string_append(logmsg, 2, "d=", s);
+if (!(s = sig->selector)) s = US"<UNSET>";
+logmsg = string_append(logmsg, 2, " s=", s);
+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_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,
+ US" [", dkim_verify_status, US" - ", dkim_verify_reason, US"]");
+else
switch (sig->verify_status)
{
case PDKIM_VERIFY_NONE:
- logmsg = string_append(logmsg, &size, &ptr, 1, "[not verified]");
+ logmsg = string_cat(logmsg, US" [not verified]");
break;
case PDKIM_VERIFY_INVALID:
- logmsg = string_append(logmsg, &size, &ptr, 1, "[invalid - ");
+ logmsg = string_cat(logmsg, US" [invalid - ");
switch (sig->verify_ext_status)
{
case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
- logmsg = string_append(logmsg, &size, &ptr, 1,
- "public key record (currently?) unavailable]");
+ logmsg = string_cat(logmsg,
+ US"public key record (currently?) unavailable]");
break;
case PDKIM_VERIFY_INVALID_BUFFER_SIZE:
- logmsg = string_append(logmsg, &size, &ptr, 1,
- "overlong public key record]");
+ logmsg = string_cat(logmsg, US"overlong public key record]");
break;
case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:
case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT:
- logmsg = string_append(logmsg, &size, &ptr, 1,
- "syntax error in public key record]");
+ logmsg = string_cat(logmsg, US"syntax error in public key record]");
+ break;
+
+ case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR:
+ logmsg = string_cat(logmsg, US"signature tag missing or invalid]");
+ break;
+
+ case PDKIM_VERIFY_INVALID_DKIM_VERSION:
+ logmsg = string_cat(logmsg, US"unsupported DKIM version]");
break;
default:
- logmsg = string_append(logmsg, &size, &ptr, 1,
- "unspecified problem]");
+ logmsg = string_cat(logmsg, US"unspecified problem]");
}
break;
case PDKIM_VERIFY_FAIL:
- logmsg =
- string_append(logmsg, &size, &ptr, 1, "[verification failed - ");
+ logmsg = string_cat(logmsg, US" [verification failed - ");
switch (sig->verify_ext_status)
{
case PDKIM_VERIFY_FAIL_BODY:
- logmsg = string_append(logmsg, &size, &ptr, 1,
- "body hash mismatch (body probably modified in transit)]");
+ logmsg = string_cat(logmsg,
+ US"body hash mismatch (body probably modified in transit)]");
break;
case PDKIM_VERIFY_FAIL_MESSAGE:
- logmsg = string_append(logmsg, &size, &ptr, 1,
- "signature did not verify (headers probably modified in transit)]");
- break;
+ logmsg = string_cat(logmsg,
+ US"signature did not verify "
+ "(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_append(logmsg, &size, &ptr, 1, "unspecified reason]");
+ logmsg = string_cat(logmsg, US"unspecified reason]");
}
break;
case PDKIM_VERIFY_PASS:
- logmsg =
- string_append(logmsg, &size, &ptr, 1, "[verification succeeded]");
+ logmsg = string_cat(logmsg, US" [verification succeeded]");
break;
}
- logmsg[ptr] = '\0';
- log_write(0, LOG_MAIN, "DKIM: %s", logmsg);
+log_write(0, LOG_MAIN, "%Y", logmsg);
+return;
+}
- /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */
- dkim_signers = string_append(dkim_signers,
- &dkim_signers_size,
- &dkim_signers_ptr, 2, sig->domain, ":");
+/* Log a line for each signature */
+void
+dkim_exim_verify_log_all(void)
+{
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
+ dkim_exim_verify_log_sig(sig);
+}
- if (sig->identity)
- dkim_signers = string_append(dkim_signers,
- &dkim_signers_size,
- &dkim_signers_ptr, 2, sig->identity, ":");
- /* Process next signature */
+void
+dkim_exim_verify_finish(void)
+{
+int rc;
+gstring * g = NULL;
+const uschar * errstr = NULL;
+
+store_pool = POOL_MESSAGE;
+
+/* Delete eventual previous signature chain */
+
+dkim_signers = NULL;
+dkim_signatures = NULL;
+
+if (dkim_collect_error)
+ {
+ log_write(0, LOG_MAIN,
+ "DKIM: Error during validation, disabling signature verification: %.100s",
+ dkim_collect_error);
+ f.dkim_disable_verify = TRUE;
+ goto out;
}
-/* NULL-terminate and chop the last colon from the domain list */
+dkim_collect_input = 0;
-if (dkim_signers)
+/* Finish DKIM operation and fetch link to signatures chain */
+
+rc = pdkim_feed_finish(dkim_verify_ctx, (pdkim_signature **)&dkim_signatures,
+ &errstr);
+if (rc != PDKIM_OK && errstr)
+ log_write(0, LOG_MAIN, "DKIM: validation error: %s", errstr);
+
+/* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */
+
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
{
- dkim_signers[dkim_signers_ptr] = '\0';
- if (Ustrlen(dkim_signers) > 0)
- dkim_signers[Ustrlen(dkim_signers) - 1] = '\0';
+ if (sig->domain) g = string_append_listele(g, ':', sig->domain);
+ if (sig->identity) g = string_append_listele(g, ':', sig->identity);
}
+gstring_release_unused(g);
+dkim_signers = string_from_gstring(g);
out:
store_pool = dkim_verify_oldpool;
}
-void
-dkim_exim_acl_setup(uschar * id)
+
+/* Args as per dkim_exim_acl_run() below */
+static int
+dkim_acl_call(uschar * id, gstring ** res_ptr,
+ uschar ** user_msgptr, uschar ** log_msgptr)
+{
+int rc;
+DEBUG(D_receive)
+ 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);
+*res_ptr = string_append_listele(*res_ptr, ':', dkim_verify_status);
+return rc;
+}
+
+
+
+/* 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
+ res_ptr ptr to growable string-list of status results,
+ appended to per ACL run
+ user_msgptr where to put a user error (for SMTP response)
+ log_msgptr where to put a logging message (not for SMTP response)
+
+Returns: OK access is granted by an ACCEPT verb
+ DISCARD access is granted by a DISCARD verb
+ FAIL access is denied
+ FAIL_DROP access is denied; drop the connection
+ DEFER can't tell at the moment
+ ERROR disaster
+*/
+
+int
+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_cur_sig = NULL;
+dkim_verify_status = US"none";
+dkim_verify_reason = US"";
dkim_cur_signer = id;
-if (dkim_disable_verify || !id || !dkim_verify_ctx)
- return;
+if (f.dkim_disable_verify || !id || !dkim_verify_ctx)
+ return OK;
-/* Find signature to run ACL on */
+/* 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;
-
/* The "dkim_domain" and "dkim_selector" expansion variables have
- related globals, since they are used in the signing code too.
- Instead of inventing separate names for verification, we set
- them here. This is easy since a domain and selector is guaranteed
- to be in a signature. The other dkim_* expansion items are
- dynamically fetched from dkim_cur_sig at expansion time (see
- function below). */
+ related globals, since they are used in the signing code too.
+ Instead of inventing separate names for verification, we set
+ them here. This is easy since a domain and selector is guaranteed
+ to be in a signature. The other dkim_* expansion items are
+ dynamically fetched from dkim_cur_sig at expansion time (see
+ dkim_exim_expand_query() below). */
+ dkim_cur_sig = sig;
dkim_signing_domain = US sig->domain;
dkim_signing_selector = US sig->selector;
- dkim_key_length = sig->sigdata.len * 8;
- return;
+ 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
+ || dkim_verify_minimal && Ustrcmp(dkim_verify_status, "pass") == 0)
+ return rc;
}
+
+if (rc != -1)
+ return rc;
+
+/* No matching sig found. Call ACL once anyway. */
+
+dkim_cur_sig = NULL;
+return dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr);
}
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)
{
case DKIM_ALGO:
- switch (dkim_cur_sig->algo)
- {
- case PDKIM_ALGO_RSA_SHA1: return US"rsa-sha1";
- case PDKIM_ALGO_RSA_SHA256:
- default: return US"rsa-sha256";
- }
+ return dkim_sig_to_a_tag(dkim_cur_sig);
case DKIM_BODYLENGTH:
return dkim_cur_sig->bodylength >= 0
- ? string_sprintf(OFF_T_FMT, (LONGLONG_T) dkim_cur_sig->bodylength)
+ ? string_sprintf("%ld", dkim_cur_sig->bodylength)
: dkim_exim_expand_defaults(what);
case DKIM_CANON_BODY:
}
case DKIM_CANON_HEADERS:
- switch (dkim_cur_sig->canon_headers)
- {
- case PDKIM_CANON_RELAXED: return US"relaxed";
- case PDKIM_CANON_SIMPLE:
- default: return US"simple";
- }
+ switch (dkim_cur_sig->canon_headers)
+ {
+ case PDKIM_CANON_RELAXED: return US"relaxed";
+ case PDKIM_CANON_SIMPLE:
+ default: return US"simple";
+ }
case DKIM_COPIEDHEADERS:
return dkim_cur_sig->copiedheaders
case DKIM_CREATED:
return dkim_cur_sig->created > 0
- ? string_sprintf("%llu", dkim_cur_sig->created)
+ ? string_sprintf("%lu", dkim_cur_sig->created)
: dkim_exim_expand_defaults(what);
case DKIM_EXPIRES:
return dkim_cur_sig->expires > 0
- ? string_sprintf("%llu", dkim_cur_sig->expires)
+ ? string_sprintf("%lu", dkim_cur_sig->expires)
: dkim_exim_expand_defaults(what);
case DKIM_HEADERNAMES:
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";
}
}
-uschar *
-dkim_exim_sign(int dkim_fd, uschar * dkim_private_key,
- const uschar * dkim_domain, uschar * dkim_selector,
- uschar * dkim_canon, uschar * dkim_sign_headers)
+void
+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;
+}
+
+
+/* Generate signatures for the given file.
+If a prefix is given, prepend it to the file for the calculations.
+
+Return:
+ NULL: error; error string written
+ string: signature header(s), or a zero-length string (not an error)
+*/
+
+gstring *
+dkim_exim_sign(int fd, off_t off, uschar * prefix,
+ struct ob_dkim * dkim, const uschar ** errstr)
{
+const uschar * dkim_domain = NULL;
int sep = 0;
-uschar *seen_items = NULL;
-int seen_items_size = 0;
-int seen_items_offset = 0;
-uschar itembuf[256];
-uschar *dkim_canon_expanded;
-uschar *dkim_sign_headers_expanded;
-uschar *dkim_private_key_expanded;
-pdkim_ctx *ctx = NULL;
-uschar *rc = NULL;
-uschar *sigbuf = NULL;
-int sigsize = 0;
-int sigptr = 0;
-pdkim_signature *signature;
-int pdkim_canon;
+gstring * seen_doms = NULL;
+pdkim_signature * sig;
+gstring * sigbuf;
int pdkim_rc;
int sread;
-char buf[4096];
+uschar buf[4096];
int save_errno = 0;
int old_pool = store_pool;
+uschar * errwhen;
+const uschar * s;
+
+if (dkim->dot_stuffed)
+ dkim_sign_ctx.flags |= PDKIM_DOT_TERM;
store_pool = POOL_MAIN;
-if (!(dkim_domain = expand_cstring(dkim_domain)))
- {
+GET_OPTION("dkim_domain");
+if ((s = dkim->dkim_domain) && !(dkim_domain = expand_cstring(s)))
/* expansion error, do not send message. */
- log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand "
- "dkim_domain: %s", expand_string_message);
- rc = NULL;
- goto CLEANUP;
- }
+ { errwhen = US"dkim_domain"; goto expand_bad; }
/* Set $dkim_domain expansion variable to each unique domain in list. */
-while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep,
- itembuf, sizeof(itembuf))))
+if (dkim_domain)
+ while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0)))
{
- if (!dkim_signing_domain || dkim_signing_domain[0] == '\0')
+ const uschar * dkim_sel;
+ int sel_sep = 0;
+
+ if (dkim_signing_domain[0] == '\0')
continue;
/* Only sign once for each domain, no matter how often it
appears in the expanded list. */
- if (seen_items)
- {
- const uschar *seen_items_list = seen_items;
- if (match_isinlist(dkim_signing_domain,
- &seen_items_list, 0, NULL, NULL, MCL_STRING, TRUE,
- NULL) == OK)
- continue;
-
- seen_items =
- string_append(seen_items, &seen_items_size, &seen_items_offset, 1, ":");
- }
-
- seen_items =
- string_append(seen_items, &seen_items_size, &seen_items_offset, 1,
- dkim_signing_domain);
- seen_items[seen_items_offset] = '\0';
-
- /* Set up $dkim_selector expansion variable. */
-
- if (!(dkim_signing_selector = expand_string(dkim_selector)))
- {
- log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand "
- "dkim_selector: %s", expand_string_message);
- rc = NULL;
- goto CLEANUP;
- }
-
- /* Get canonicalization to use */
-
- dkim_canon_expanded = dkim_canon ? expand_string(dkim_canon) : US"relaxed";
- if (!dkim_canon_expanded)
- {
- /* expansion error, do not send message. */
- log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand "
- "dkim_canon: %s", expand_string_message);
- rc = NULL;
- goto CLEANUP;
- }
-
- if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0)
- pdkim_canon = PDKIM_CANON_RELAXED;
- else if (Ustrcmp(dkim_canon_expanded, "simple") == 0)
- pdkim_canon = PDKIM_CANON_SIMPLE;
- else
- {
- log_write(0, LOG_MAIN,
- "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n",
- dkim_canon_expanded);
- pdkim_canon = PDKIM_CANON_RELAXED;
- }
-
- dkim_sign_headers_expanded = NULL;
- if (dkim_sign_headers)
- if (!(dkim_sign_headers_expanded = expand_string(dkim_sign_headers)))
- {
- log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand "
- "dkim_sign_headers: %s", expand_string_message);
- rc = NULL;
- goto CLEANUP;
- }
- /* else pass NULL, which means default header 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;
- /* Get private key to use. */
+ seen_doms = string_append_listele(seen_doms, ':', dkim_signing_domain);
- if (!(dkim_private_key_expanded = expand_string(dkim_private_key)))
- {
- log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand "
- "dkim_private_key: %s", expand_string_message);
- rc = NULL;
- goto CLEANUP;
- }
+ /* Set $dkim_selector expansion variable to each selector in list,
+ for this domain. */
- if ( Ustrlen(dkim_private_key_expanded) == 0
- || Ustrcmp(dkim_private_key_expanded, "0") == 0
- || Ustrcmp(dkim_private_key_expanded, "false") == 0
- )
- continue; /* don't sign, but no error */
+ GET_OPTION("dkim_selector");
+ if (!(dkim_sel = expand_string(dkim->dkim_selector)))
+ { errwhen = US"dkim_selector"; goto expand_bad; }
- if (dkim_private_key_expanded[0] == '/')
+ while ((dkim_signing_selector = string_nextinlist(&dkim_sel, &sel_sep,
+ NULL, 0)))
{
- int privkey_fd = 0;
-
- /* Looks like a filename, load the private key. */
-
- memset(big_buffer, 0, big_buffer_size);
- privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY);
- if (privkey_fd < 0)
+ uschar * dkim_canon_expanded;
+ int pdkim_canon;
+ uschar * dkim_sign_headers_expanded = NULL;
+ uschar * dkim_private_key_expanded;
+ uschar * dkim_hash_expanded;
+ uschar * dkim_identity_expanded = NULL;
+ uschar * dkim_timestamps_expanded = NULL;
+ unsigned long tval = 0, xval = 0;
+
+ /* 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. */
+ { errwhen = US"dkim_canon"; goto expand_bad; }
+
+ if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0)
+ pdkim_canon = PDKIM_CANON_RELAXED;
+ else if (Ustrcmp(dkim_canon_expanded, "simple") == 0)
+ pdkim_canon = PDKIM_CANON_SIMPLE;
+ else
{
- log_write(0, LOG_MAIN | LOG_PANIC, "unable to open "
- "private key file for reading: %s",
- dkim_private_key_expanded);
- rc = NULL;
- goto CLEANUP;
+ log_write(0, LOG_MAIN,
+ "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n",
+ dkim_canon_expanded);
+ pdkim_canon = PDKIM_CANON_RELAXED;
}
- if (read(privkey_fd, big_buffer, big_buffer_size - 2) < 0)
+ 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; }
+ /* else pass NULL, which means default header list */
+
+ /* 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; }
+
+ if ( Ustrlen(dkim_private_key_expanded) == 0
+ || Ustrcmp(dkim_private_key_expanded, "0") == 0
+ || Ustrcmp(dkim_private_key_expanded, "false") == 0
+ )
+ continue; /* don't sign, but no error */
+
+ if ( dkim_private_key_expanded[0] == '/'
+ && !(dkim_private_key_expanded =
+ 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
+ {
+ 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,
+ dkim_private_key_expanded,
+ dkim_hash_expanded,
+ errstr
+ )))
+ goto bad;
+ dkim_private_key_expanded[0] = '\0';
+
+ pdkim_set_optional(sig,
+ CS dkim_sign_headers_expanded,
+ CS dkim_identity_expanded,
+ pdkim_canon,
+ pdkim_canon, -1, tval, xval);
+
+ 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
{
- log_write(0, LOG_MAIN|LOG_PANIC, "unable to read private key file: %s",
- dkim_private_key_expanded);
- rc = NULL;
- goto CLEANUP;
+ pdkim_signature * n = dkim_sign_ctx.sig;
+ while (n->next) n = n->next;
+ n->next = sig;
}
-
- (void) close(privkey_fd);
- dkim_private_key_expanded = big_buffer;
}
+ }
- ctx = pdkim_init_sign( (char *) dkim_signing_domain,
- (char *) dkim_signing_selector,
- (char *) dkim_private_key_expanded,
- PDKIM_ALGO_RSA_SHA256);
- pdkim_set_optional(ctx,
- (char *) dkim_sign_headers_expanded,
- NULL,
- pdkim_canon,
- pdkim_canon, -1, 0, 0);
+/* We may need to carry on with the data-feed even if there are no DKIM sigs to
+produce, if some other package (eg. ARC) is signing. */
- lseek(dkim_fd, 0, SEEK_SET);
+if (!dkim_sign_ctx.sig && !dkim->force_bodyhash)
+ {
+ DEBUG(D_transport) debug_printf("DKIM: no viable signatures to use\n");
+ sigbuf = string_get(1); /* return a zero-len string */
+ }
+else
+ {
+ if (prefix && (pdkim_rc = pdkim_feed(&dkim_sign_ctx, prefix, Ustrlen(prefix))) != PDKIM_OK)
+ goto pk_bad;
- while ((sread = read(dkim_fd, &buf, 4096)) > 0)
- if (pdkim_feed(ctx, buf, sread) != PDKIM_OK)
- {
- rc = NULL;
- goto CLEANUP;
- }
+ if (lseek(fd, off, SEEK_SET) < 0)
+ sread = -1;
+ else
+ while ((sread = read(fd, &buf, sizeof(buf))) > 0)
+ if ((pdkim_rc = pdkim_feed(&dkim_sign_ctx, buf, sread)) != PDKIM_OK)
+ goto pk_bad;
/* Handle failed read above. */
if (sread == -1)
{
debug_printf("DKIM: Error reading -K file.\n");
save_errno = errno;
- rc = NULL;
- goto CLEANUP;
+ goto bad;
}
- if ((pdkim_rc = pdkim_feed_finish(ctx, &signature)) != PDKIM_OK)
+ /* Build string of headers, one per signature */
+
+ if ((pdkim_rc = pdkim_feed_finish(&dkim_sign_ctx, &sig, errstr)) != PDKIM_OK)
+ goto pk_bad;
+
+ if (!sig)
{
- log_write(0, LOG_MAIN|LOG_PANIC, "DKIM: signing failed (RC %d)", pdkim_rc);
- rc = NULL;
- goto CLEANUP;
+ DEBUG(D_transport) debug_printf("DKIM: no signatures to use\n");
+ sigbuf = string_get(1); /* return a zero-len string */
}
+ else for (sigbuf = NULL; sig; sig = sig->next)
+ sigbuf = string_append(sigbuf, 2, US sig->signature_header, US"\r\n");
+ }
- sigbuf = string_append(sigbuf, &sigsize, &sigptr, 2,
- US signature->signature_header, US"\r\n");
+CLEANUP:
+ (void) string_from_gstring(sigbuf);
+ store_pool = old_pool;
+ errno = save_errno;
+ return sigbuf;
+
+pk_bad:
+ log_write(0, LOG_MAIN|LOG_PANIC,
+ "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc));
+bad:
+ sigbuf = NULL;
+ goto CLEANUP;
- pdkim_free_ctx(ctx);
- ctx = NULL;
- }
+expand_bad:
+ *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)
+{
+int start = 0; /* compiler quietening */
-if (sigbuf)
+DEBUG(D_acl) start = gstring_length(g);
+
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
{
- sigbuf[sigptr] = '\0';
- rc = sigbuf;
+ g = string_catn(g, US";\n\tdkim=", 8);
+
+ if (sig->verify_status & PDKIM_VERIFY_POLICY)
+ g = string_append(g, 5,
+ US"policy (", dkim_verify_status, US" - ", dkim_verify_reason, US")");
+ else switch(sig->verify_status)
+ {
+ case PDKIM_VERIFY_NONE: g = string_cat(g, US"none"); break;
+ case PDKIM_VERIFY_INVALID:
+ switch (sig->verify_ext_status)
+ {
+ case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
+ g = string_cat(g, US"tmperror (pubkey unavailable)\n\t\t"); break;
+ case PDKIM_VERIFY_INVALID_BUFFER_SIZE:
+ g = string_cat(g, US"permerror (overlong public key record)\n\t\t"); break;
+ case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:
+ case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT:
+ g = string_cat(g, US"neutral (public key record import problem)\n\t\t");
+ break;
+ case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR:
+ g = string_cat(g, US"neutral (signature tag missing or invalid)\n\t\t");
+ break;
+ case PDKIM_VERIFY_INVALID_DKIM_VERSION:
+ g = string_cat(g, US"neutral (unsupported DKIM version)\n\t\t");
+ break;
+ default:
+ g = string_cat(g, US"permerror (unspecified problem)\n\t\t"); break;
+ }
+ break;
+ case PDKIM_VERIFY_FAIL:
+ switch (sig->verify_ext_status)
+ {
+ case PDKIM_VERIFY_FAIL_BODY:
+ g = string_cat(g,
+ US"fail (body hash mismatch; body probably modified in transit)\n\t\t");
+ break;
+ case PDKIM_VERIFY_FAIL_MESSAGE:
+ 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;
+ }
+ break;
+ case PDKIM_VERIFY_PASS: g = string_cat(g, US"pass"); break;
+ default: g = string_cat(g, US"permerror"); break;
+ }
+ if (sig->domain) g = string_append(g, 2, US" header.d=", sig->domain);
+ if (sig->identity) g = string_append(g, 2, US" header.i=", sig->identity);
+ if (sig->selector) g = string_append(g, 2, US" header.s=", sig->selector);
+ g = string_append(g, 2, US" header.a=", dkim_sig_to_a_tag(sig));
}
-else
- rc = US"";
-CLEANUP:
-if (ctx)
- pdkim_free_ctx(ctx);
-store_pool = old_pool;
-errno = save_errno;
-return rc;
+DEBUG(D_acl)
+ if (gstring_length(g) == start)
+ debug_printf("DKIM:\tno authres\n");
+ else
+ debug_printf("DKIM:\tauthres '%.*s'\n", g->ptr - start - 3, g->s + start + 3);
+return g;
}
-#endif
+
+# endif /*!MACRO_PREDEF*/
+#endif /*!DISABLE_DKIM*/
git://git.exim.org / exim.git / blobdiff