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-rw-r--r--src/dkim.c891
1 files changed, 891 insertions, 0 deletions
diff --git a/src/dkim.c b/src/dkim.c
new file mode 100644
index 0000000..92adb35
--- /dev/null
+++ b/src/dkim.c
@@ -0,0 +1,891 @@
+/*************************************************
+* Exim - an Internet mail transport agent *
+*************************************************/
+
+/* 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
+ receive.c, transport.c and transports/smtp.c */
+
+#include "exim.h"
+
+#ifndef DISABLE_DKIM
+
+# 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_cur_sig = NULL;
+static const uschar * dkim_collect_error = NULL;
+
+#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 = store_get_dns_answer();
+dns_scan dnss;
+rmark reset_point = store_mark();
+gstring * g = NULL;
+
+lookup_dnssec_authenticated = NULL;
+if (dns_lookup(dnsa, name, T_TXT, NULL) != DNS_SUCCEED)
+ return NULL; /*XXX better error detail? logging? */
+
+/* Search for TXT record */
+
+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)
+ {
+ uschar len = 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;
+ }
+
+ /* check if this looks like a DKIM record */
+ if (Ustrncmp(g->s, "v=", 2) != 0 || strncasecmp(CS g->s, "v=dkim", 6) == 0)
+ {
+ gstring_release_unused(g);
+ return string_from_gstring(g);
+ }
+
+ if (g) g->ptr = 0; /* overwrite previous record */
+ }
+
+bad:
+store_reset(reset_point);
+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)
+{
+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. */
+
+dkim_verify_oldpool = store_pool;
+store_pool = POOL_PERM;
+
+/* Free previous context if there is one */
+
+if (dkim_verify_ctx)
+ pdkim_free_ctx(dkim_verify_ctx);
+
+/* Create new context */
+
+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();
+
+store_pool = dkim_verify_oldpool;
+}
+
+
+void
+dkim_exim_verify_feed(uschar * data, int len)
+{
+int rc;
+
+store_pool = POOL_PERM;
+if ( dkim_collect_input
+ && (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;
+}
+
+
+/* Log the result for the given signature */
+static void
+dkim_exim_verify_log_sig(pdkim_signature * sig)
+{
+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;
+ }
+
+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_cat(logmsg, US" [not verified]");
+ break;
+
+ case PDKIM_VERIFY_INVALID:
+ logmsg = string_cat(logmsg, US" [invalid - ");
+ switch (sig->verify_ext_status)
+ {
+ case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
+ logmsg = string_cat(logmsg,
+ US"public key record (currently?) unavailable]");
+ break;
+
+ case PDKIM_VERIFY_INVALID_BUFFER_SIZE:
+ logmsg = string_cat(logmsg, US"overlong public key record]");
+ break;
+
+ case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:
+ case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT:
+ 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_cat(logmsg, US"unspecified problem]");
+ }
+ break;
+
+ case PDKIM_VERIFY_FAIL:
+ logmsg = string_cat(logmsg, US" [verification failed - ");
+ switch (sig->verify_ext_status)
+ {
+ case PDKIM_VERIFY_FAIL_BODY:
+ logmsg = string_cat(logmsg,
+ US"body hash mismatch (body probably modified in transit)]");
+ break;
+
+ case PDKIM_VERIFY_FAIL_MESSAGE:
+ 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_cat(logmsg, US"unspecified reason]");
+ }
+ break;
+
+ case PDKIM_VERIFY_PASS:
+ logmsg = string_cat(logmsg, US" [verification succeeded]");
+ break;
+ }
+
+log_write(0, LOG_MAIN, "%s", string_from_gstring(logmsg));
+return;
+}
+
+
+/* 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);
+}
+
+
+void
+dkim_exim_verify_finish(void)
+{
+int rc;
+gstring * g = NULL;
+const uschar * errstr = NULL;
+
+store_pool = POOL_PERM;
+
+/* 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;
+ }
+
+dkim_collect_input = 0;
+
+/* 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)
+ {
+ 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;
+
+out:
+store_pool = dkim_verify_oldpool;
+}
+
+
+
+/* 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 dkim_cur_signer='%s'\n", id);
+
+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.
+
+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)
+{
+uschar * cmp_val;
+int rc = -1;
+
+dkim_verify_status = US"none";
+dkim_verify_reason = US"";
+dkim_cur_signer = id;
+
+if (f.dkim_disable_verify || !id || !dkim_verify_ctx)
+ return OK;
+
+/* Find signatures to run ACL on */
+
+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
+ )
+ {
+ /* 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
+ 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->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)
+ 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);
+}
+
+
+static uschar *
+dkim_exim_expand_defaults(int what)
+{
+switch (what)
+ {
+ case DKIM_ALGO: return US"";
+ case DKIM_BODYLENGTH: return US"9999999999999";
+ case DKIM_CANON_BODY: return US"";
+ case DKIM_CANON_HEADERS: return US"";
+ case DKIM_COPIEDHEADERS: return US"";
+ case DKIM_CREATED: return US"0";
+ case DKIM_EXPIRES: return US"9999999999999";
+ case DKIM_HEADERNAMES: return US"";
+ case DKIM_IDENTITY: return US"";
+ case DKIM_KEY_GRANULARITY: return US"*";
+ case DKIM_KEY_SRVTYPE: return US"*";
+ case DKIM_KEY_NOTES: return US"";
+ case DKIM_KEY_TESTING: return US"0";
+ case DKIM_NOSUBDOMAINS: return US"0";
+ case DKIM_VERIFY_STATUS: return US"none";
+ case DKIM_VERIFY_REASON: return US"";
+ default: return US"";
+ }
+}
+
+
+uschar *
+dkim_exim_expand_query(int what)
+{
+if (!dkim_verify_ctx || f.dkim_disable_verify || !dkim_cur_sig)
+ return dkim_exim_expand_defaults(what);
+
+switch (what)
+ {
+ case DKIM_ALGO:
+ return dkim_sig_to_a_tag(dkim_cur_sig);
+
+ case DKIM_BODYLENGTH:
+ return dkim_cur_sig->bodylength >= 0
+ ? string_sprintf("%ld", dkim_cur_sig->bodylength)
+ : dkim_exim_expand_defaults(what);
+
+ case DKIM_CANON_BODY:
+ switch (dkim_cur_sig->canon_body)
+ {
+ case PDKIM_CANON_RELAXED: return US"relaxed";
+ case PDKIM_CANON_SIMPLE:
+ default: return US"simple";
+ }
+
+ 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";
+ }
+
+ case DKIM_COPIEDHEADERS:
+ return dkim_cur_sig->copiedheaders
+ ? US dkim_cur_sig->copiedheaders : dkim_exim_expand_defaults(what);
+
+ case DKIM_CREATED:
+ return dkim_cur_sig->created > 0
+ ? string_sprintf("%lu", dkim_cur_sig->created)
+ : dkim_exim_expand_defaults(what);
+
+ case DKIM_EXPIRES:
+ return dkim_cur_sig->expires > 0
+ ? string_sprintf("%lu", dkim_cur_sig->expires)
+ : dkim_exim_expand_defaults(what);
+
+ case DKIM_HEADERNAMES:
+ return dkim_cur_sig->headernames
+ ? dkim_cur_sig->headernames : dkim_exim_expand_defaults(what);
+
+ case DKIM_IDENTITY:
+ return dkim_cur_sig->identity
+ ? US dkim_cur_sig->identity : dkim_exim_expand_defaults(what);
+
+ case DKIM_KEY_GRANULARITY:
+ return dkim_cur_sig->pubkey
+ ? dkim_cur_sig->pubkey->granularity
+ ? US dkim_cur_sig->pubkey->granularity
+ : dkim_exim_expand_defaults(what)
+ : dkim_exim_expand_defaults(what);
+
+ case DKIM_KEY_SRVTYPE:
+ return dkim_cur_sig->pubkey
+ ? dkim_cur_sig->pubkey->srvtype
+ ? US dkim_cur_sig->pubkey->srvtype
+ : dkim_exim_expand_defaults(what)
+ : dkim_exim_expand_defaults(what);
+
+ case DKIM_KEY_NOTES:
+ return dkim_cur_sig->pubkey
+ ? dkim_cur_sig->pubkey->notes
+ ? US dkim_cur_sig->pubkey->notes
+ : dkim_exim_expand_defaults(what)
+ : dkim_exim_expand_defaults(what);
+
+ case DKIM_KEY_TESTING:
+ return dkim_cur_sig->pubkey
+ ? dkim_cur_sig->pubkey->testing
+ ? US"1"
+ : dkim_exim_expand_defaults(what)
+ : dkim_exim_expand_defaults(what);
+
+ case DKIM_NOSUBDOMAINS:
+ return dkim_cur_sig->pubkey
+ ? dkim_cur_sig->pubkey->no_subdomaining
+ ? US"1"
+ : dkim_exim_expand_defaults(what)
+ : dkim_exim_expand_defaults(what);
+
+ case DKIM_VERIFY_STATUS:
+ switch (dkim_cur_sig->verify_status)
+ {
+ case PDKIM_VERIFY_INVALID: return US"invalid";
+ case PDKIM_VERIFY_FAIL: return US"fail";
+ case PDKIM_VERIFY_PASS: return US"pass";
+ case PDKIM_VERIFY_NONE:
+ default: return US"none";
+ }
+
+ case DKIM_VERIFY_REASON:
+ switch (dkim_cur_sig->verify_ext_status)
+ {
+ case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
+ 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";
+ }
+
+ default:
+ return US"";
+ }
+}
+
+
+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;
+gstring * seen_doms = NULL;
+pdkim_signature * sig;
+gstring * sigbuf;
+int pdkim_rc;
+int sread;
+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 ((s = dkim->dkim_domain) && !(dkim_domain = expand_cstring(s)))
+ /* expansion error, do not send message. */
+ { errwhen = US"dkim_domain"; goto expand_bad; }
+
+/* Set $dkim_domain expansion variable to each unique domain in list. */
+
+if (dkim_domain)
+ while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 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. */
+
+ 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;
+
+ seen_doms = string_append_listele(seen_doms, ':', dkim_signing_domain);
+
+ /* Set $dkim_selector expansion variable to each selector in list,
+ for this domain. */
+
+ if (!(dkim_sel = expand_string(dkim->dkim_selector)))
+ { errwhen = US"dkim_selector"; goto expand_bad; }
+
+ while ((dkim_signing_selector = string_nextinlist(&dkim_sel, &sel_sep,
+ NULL, 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 */
+
+ 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,
+ "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n",
+ dkim_canon_expanded);
+ pdkim_canon = PDKIM_CANON_RELAXED;
+ }
+
+ 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. */
+
+ 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;
+
+ if (!(dkim_hash_expanded = expand_string(dkim->dkim_hash)))
+ { errwhen = US"dkim_hash"; goto expand_bad; }
+
+ 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;
+
+ 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);
+
+ 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;
+
+ if (!dkim_sign_ctx.sig) /* link sig to context chain */
+ dkim_sign_ctx.sig = sig;
+ else
+ {
+ pdkim_signature * n = dkim_sign_ctx.sig;
+ while (n->next) n = n->next;
+ n->next = sig;
+ }
+ }
+ }
+
+/* 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. */
+
+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;
+
+ 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;
+ goto bad;
+ }
+
+ /* 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)
+ {
+ 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");
+ }
+
+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;
+
+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 */
+
+DEBUG(D_acl) start = g->ptr;
+
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
+ {
+ 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));
+ }
+
+DEBUG(D_acl)
+ if (g->ptr == start)
+ debug_printf("DKIM: no authres\n");
+ else
+ debug_printf("DKIM: authres '%.*s'\n", g->ptr - start - 3, g->s + start + 3);
+return g;
+}
+
+
+# endif /*!MACRO_PREDEF*/
+#endif /*!DISABLE_DKIM*/
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-22 21:59:51 +0000