X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/40c90bca9f7e2952bd64faebceb53538f80805a7..777cc7485cb3242eb627fbd9fa004b7a4e58ae92:/src/src/dmarc.c diff --git a/src/src/dmarc.c b/src/src/dmarc.c index c005d4ab9..2e43f846d 100644 --- a/src/src/dmarc.c +++ b/src/src/dmarc.c @@ -1,8 +1,9 @@ /************************************************* * Exim - an Internet mail transport agent * *************************************************/ -/* Experimental DMARC support. +/* DMARC support. Copyright (c) Todd Lyons 2012 - 2014 + Copyright (c) The Exim Maintainers 2019 License: GPL */ /* Portions Copyright (c) 2012, 2013, The Trusted Domain Project; @@ -11,8 +12,8 @@ /* Code for calling dmarc checks via libopendmarc. Called from acl.c. */ #include "exim.h" -#ifdef EXPERIMENTAL_DMARC -# if !defined EXPERIMENTAL_SPF +#ifdef SUPPORT_DMARC +# if !defined SUPPORT_SPF # error SPF must also be enabled for DMARC # elif defined DISABLE_DKIM # error DKIM must also be enabled for DMARC @@ -28,7 +29,6 @@ OPENDMARC_STATUS_T libdm_status, action, dmarc_policy; OPENDMARC_STATUS_T da, sa, action; BOOL dmarc_abort = FALSE; uschar *dmarc_pass_fail = US"skipped"; -extern pdkim_signature *dkim_signatures; header_line *from_header = NULL; extern SPF_response_t *spf_response; int dmarc_spf_ares_result = 0; @@ -44,6 +44,7 @@ typedef struct dmarc_exim_p { } dmarc_exim_p; static dmarc_exim_p dmarc_policy_description[] = { + /* name value */ { US"", DMARC_RECORD_P_UNSPECIFIED }, { US"none", DMARC_RECORD_P_NONE }, { US"quarantine", DMARC_RECORD_P_QUARANTINE }, @@ -78,13 +79,11 @@ return eblock; messages on the same SMTP connection (that come from the same host with the same HELO string) */ -int dmarc_init() +int +dmarc_init() { int *netmask = NULL; /* Ignored */ int is_ipv6 = 0; -char *tld_file = (dmarc_tld_file == NULL) ? - "/etc/exim/opendmarc.tlds" : - (char *)dmarc_tld_file; /* Set some sane defaults. Also clears previous results when * multiple messages in one connection. */ @@ -93,14 +92,13 @@ dmarc_status = US"none"; dmarc_abort = FALSE; dmarc_pass_fail = US"skipped"; dmarc_used_domain = US""; -dmarc_ar_header = NULL; -dmarc_has_been_checked = FALSE; +f.dmarc_has_been_checked = FALSE; header_from_sender = NULL; spf_sender_domain = NULL; spf_human_readable = NULL; /* ACLs have "control=dmarc_disable_verify" */ -if (dmarc_disable_verify == TRUE) +if (f.dmarc_disable_verify == TRUE) return OK; (void) memset(&dmarc_ctx, '\0', sizeof dmarc_ctx); @@ -112,22 +110,27 @@ if (libdm_status != DMARC_PARSE_OKAY) opendmarc_policy_status_to_str(libdm_status)); dmarc_abort = TRUE; } -if (dmarc_tld_file == NULL) +if (!dmarc_tld_file || !*dmarc_tld_file) + { + DEBUG(D_receive) debug_printf("DMARC: no dmarc_tld_file\n"); dmarc_abort = TRUE; -else if (opendmarc_tld_read_file(tld_file, NULL, NULL, NULL)) + } +else if (opendmarc_tld_read_file(CS dmarc_tld_file, NULL, NULL, NULL)) { - log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list %s: %d", - tld_file, errno); + log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list '%s': %s", + dmarc_tld_file, strerror(errno)); dmarc_abort = TRUE; } -if (sender_host_address == NULL) +if (!sender_host_address) + { + DEBUG(D_receive) debug_printf("DMARC: no sender_host_address\n"); dmarc_abort = TRUE; + } /* This catches locally originated email and startup errors above. */ if (!dmarc_abort) { is_ipv6 = string_is_ip_address(sender_host_address, netmask) == 6; - dmarc_pctx = opendmarc_policy_connect_init(sender_host_address, is_ipv6); - if (dmarc_pctx == NULL) + if (!(dmarc_pctx = opendmarc_policy_connect_init(sender_host_address, is_ipv6))) { log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure creating policy context: ip=%s", sender_host_address); @@ -140,27 +143,28 @@ return OK; /* dmarc_store_data stores the header data so that subsequent - * dmarc_process can access the data */ +dmarc_process can access the data */ -int dmarc_store_data(header_line *hdr) { - /* No debug output because would change every test debug output */ - if (dmarc_disable_verify != TRUE) - from_header = hdr; - return OK; +int +dmarc_store_data(header_line *hdr) +{ +/* No debug output because would change every test debug output */ +if (!f.dmarc_disable_verify) + from_header = hdr; +return OK; } static void dmarc_send_forensic_report(u_char **ruf) { -int c; uschar *recipient, *save_sender; BOOL send_status = FALSE; error_block *eblock = NULL; FILE *message_file = NULL; /* Earlier ACL does not have *required* control=dmarc_enable_forensic */ -if (!dmarc_enable_forensic) +if (!f.dmarc_enable_forensic) return; if ( dmarc_policy == DMARC_POLICY_REJECT && action == DMARC_RESULT_REJECT @@ -174,15 +178,12 @@ if ( dmarc_policy == DMARC_POLICY_REJECT && action == DMARC_RESULT_REJECT eblock = add_to_eblock(eblock, US"Sender IP Address", sender_host_address); eblock = add_to_eblock(eblock, US"Received Date", tod_stamp(tod_full)); eblock = add_to_eblock(eblock, US"SPF Alignment", - (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?US"yes":US"no"); + sa == DMARC_POLICY_SPF_ALIGNMENT_PASS ? US"yes" : US"no"); eblock = add_to_eblock(eblock, US"DKIM Alignment", - (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?US"yes":US"no"); + da == DMARC_POLICY_DKIM_ALIGNMENT_PASS ? US"yes" : US"no"); eblock = add_to_eblock(eblock, US"DMARC Results", dmarc_status_text); - /* Set a sane default envelope sender */ - dsn_from = dmarc_forensic_sender ? dmarc_forensic_sender : - dsn_from ? dsn_from : - string_sprintf("do-not-reply@%s",primary_hostname); - for (c = 0; ruf[c]; c++) + + for (int c = 0; ruf[c]; c++) { recipient = string_copylc(ruf[c]); if (Ustrncmp(recipient, "mailto:",7)) @@ -191,25 +192,40 @@ if ( dmarc_policy == DMARC_POLICY_REJECT && action == DMARC_RESULT_REJECT recipient += 7; DEBUG(D_receive) debug_printf("DMARC forensic report to %s%s\n", recipient, - (host_checking || running_in_test_harness) ? " (not really)" : ""); - if (host_checking || running_in_test_harness) + (host_checking || f.running_in_test_harness) ? " (not really)" : ""); + if (host_checking || f.running_in_test_harness) continue; - save_sender = sender_address; - sender_address = recipient; - send_status = moan_to_sender(ERRMESS_DMARC_FORENSIC, eblock, - header_list, message_file, FALSE); - sender_address = save_sender; - if (!send_status) + if (!moan_send_message(recipient, ERRMESS_DMARC_FORENSIC, eblock, + header_list, message_file, NULL)) log_write(0, LOG_MAIN|LOG_PANIC, "failure to send DMARC forensic report to %s", recipient); } } } + +/* Look up a DNS dmarc record for the given domain. Return it or NULL */ + +static uschar * +dmarc_dns_lookup(uschar * dom) +{ +dns_answer * dnsa = store_get_dns_answer(); +dns_scan dnss; +int rc = dns_lookup(dnsa, string_sprintf("_dmarc.%s", dom), T_TXT, NULL); + +if (rc == DNS_SUCCEED) + 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 && rr->size > 3) + return string_copyn(US rr->data, rr->size); +return NULL; +} + + /* dmarc_process adds the envelope sender address to the existing - context (if any), retrieves the result, sets up expansion - strings and evaluates the condition outcome. */ +context (if any), retrieves the result, sets up expansion +strings and evaluates the condition outcome. */ int dmarc_process() @@ -217,16 +233,14 @@ dmarc_process() int sr, origin; /* used in SPF section */ int dmarc_spf_result = 0; /* stores spf into dmarc conn ctx */ int tmp_ans, c; -pdkim_signature *sig = NULL; +pdkim_signature * sig = dkim_signatures; +uschar * rr; BOOL has_dmarc_record = TRUE; u_char **ruf; /* forensic report addressees, if called for */ /* ACLs have "control=dmarc_disable_verify" */ -if (dmarc_disable_verify) - { - dmarc_ar_header = dmarc_auth_results_header(from_header, NULL); +if (f.dmarc_disable_verify) return OK; - } /* Store the header From: sender domain for this part of DMARC. * If there is no from_header struct, then it's likely this message @@ -234,31 +248,34 @@ if (dmarc_disable_verify) * the entire DMARC system if we can't find a From: header....or if * there was a previous error. */ -if (!from_header || dmarc_abort) +if (!from_header) + { + DEBUG(D_receive) debug_printf("DMARC: no From: header\n"); dmarc_abort = TRUE; -else + } +else if (!dmarc_abort) { - uschar * errormsg; - int dummy, domain; - uschar * p; - uschar saveend; - - parse_allow_group = TRUE; - p = parse_find_address_end(from_header->text, FALSE); - saveend = *p; *p = '\0'; - if ((header_from_sender = parse_extract_address(from_header->text, &errormsg, - &dummy, &dummy, &domain, FALSE))) - header_from_sender += domain; - *p = saveend; - - /* The opendmarc library extracts the domain from the email address, but - * only try to store it if it's not empty. Otherwise, skip out of DMARC. */ - if (!header_from_sender || (strcmp( CCS header_from_sender, "") == 0)) - dmarc_abort = TRUE; - libdm_status = dmarc_abort ? - DMARC_PARSE_OKAY : - opendmarc_policy_store_from_domain(dmarc_pctx, header_from_sender); - if (libdm_status != DMARC_PARSE_OKAY) + uschar * errormsg; + int dummy, domain; + uschar * p; + uschar saveend; + + f.parse_allow_group = TRUE; + p = parse_find_address_end(from_header->text, FALSE); + saveend = *p; *p = '\0'; + if ((header_from_sender = parse_extract_address(from_header->text, &errormsg, + &dummy, &dummy, &domain, FALSE))) + header_from_sender += domain; + *p = saveend; + + /* The opendmarc library extracts the domain from the email address, but + * only try to store it if it's not empty. Otherwise, skip out of DMARC. */ + if (!header_from_sender || (strcmp( CCS header_from_sender, "") == 0)) + dmarc_abort = TRUE; + libdm_status = dmarc_abort + ? DMARC_PARSE_OKAY + : opendmarc_policy_store_from_domain(dmarc_pctx, header_from_sender); + if (libdm_status != DMARC_PARSE_OKAY) { log_write(0, LOG_MAIN|LOG_PANIC, "failure to store header From: in DMARC: %s, header was '%s'", @@ -271,6 +288,8 @@ else * instead do this in the ACLs. */ if (!dmarc_abort && !sender_host_authenticated) { + uschar * dmarc_domain; + /* Use the envelope sender domain for this part of DMARC */ spf_sender_domain = expand_string(US"$sender_address_domain"); if (!spf_response) @@ -308,7 +327,7 @@ if (!dmarc_abort && !sender_host_authenticated) sr == SPF_RESULT_PERMERROR ? ARES_RESULT_PERMERROR : ARES_RESULT_UNKNOWN; origin = DMARC_POLICY_SPF_ORIGIN_MAILFROM; - spf_human_readable = (uschar *)spf_response->header_comment; + spf_human_readable = US spf_response->header_comment; DEBUG(D_receive) debug_printf("DMARC using SPF sender domain = %s\n", spf_sender_domain); } @@ -325,18 +344,18 @@ if (!dmarc_abort && !sender_host_authenticated) /* Now we cycle through the dkim signature results and put into * the opendmarc context, further building the DMARC reply. */ - sig = dkim_signatures; dkim_history_buffer = US""; while (sig) { int dkim_result, dkim_ares_result, vs, ves; - vs = sig->verify_status; + + vs = sig->verify_status & ~PDKIM_VERIFY_POLICY; ves = sig->verify_ext_status; dkim_result = vs == PDKIM_VERIFY_PASS ? DMARC_POLICY_DKIM_OUTCOME_PASS : vs == PDKIM_VERIFY_FAIL ? DMARC_POLICY_DKIM_OUTCOME_FAIL : vs == PDKIM_VERIFY_INVALID ? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL : DMARC_POLICY_DKIM_OUTCOME_NONE; - libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, (uschar *)sig->domain, + libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, US sig->domain, dkim_result, US""); DEBUG(D_receive) debug_printf("DMARC adding DKIM sender domain = %s\n", sig->domain); @@ -360,7 +379,15 @@ if (!dmarc_abort && !sender_host_authenticated) sig->domain, dkim_ares_result); sig = sig->next; } - libdm_status = opendmarc_policy_query_dmarc(dmarc_pctx, US""); + + /* Look up DMARC policy record in DNS. We do this explicitly, rather than + letting the dmarc library do it with opendmarc_policy_query_dmarc(), so that + our dns access path is used for debug tracing and for the testsuite + diversion. */ + + libdm_status = (rr = dmarc_dns_lookup(header_from_sender)) + ? opendmarc_policy_store_dmarc(dmarc_pctx, rr, header_from_sender, NULL) + : DMARC_DNS_ERROR_NO_RECORD; switch (libdm_status) { case DMARC_DNS_ERROR_NXDOMAIN: @@ -398,21 +425,20 @@ if (!dmarc_abort && !sender_host_authenticated) } /* Can't use exim's string manipulation functions so allocate memory - * for libopendmarc using its max hostname length definition. */ + for libopendmarc using its max hostname length definition. */ - uschar *dmarc_domain = (uschar *)calloc(DMARC_MAXHOSTNAMELEN, sizeof(uschar)); + dmarc_domain = store_get(DMARC_MAXHOSTNAMELEN, TRUE); libdm_status = opendmarc_policy_fetch_utilized_domain(dmarc_pctx, dmarc_domain, DMARC_MAXHOSTNAMELEN-1); - dmarc_used_domain = string_copy(dmarc_domain); - free(dmarc_domain); + store_release_above(dmarc_domain + Ustrlen(dmarc_domain)+1); + dmarc_used_domain = dmarc_domain; if (libdm_status != DMARC_PARSE_OKAY) log_write(0, LOG_MAIN|LOG_PANIC, "failure to read domainname used for DMARC lookup: %s", opendmarc_policy_status_to_str(libdm_status)); - libdm_status = opendmarc_get_policy_to_enforce(dmarc_pctx); - dmarc_policy = libdm_status; + dmarc_policy = libdm_status = opendmarc_get_policy_to_enforce(dmarc_pctx); switch(libdm_status) { case DMARC_POLICY_ABSENT: /* No DMARC record found */ @@ -464,13 +490,13 @@ if (!dmarc_abort && !sender_host_authenticated) log_write(0, LOG_MAIN|LOG_PANIC, "failure to read DMARC alignment: %s", opendmarc_policy_status_to_str(libdm_status)); - if (has_dmarc_record == TRUE) + if (has_dmarc_record) { log_write(0, LOG_MAIN, "DMARC results: spf_domain=%s dmarc_domain=%s " "spf_align=%s dkim_align=%s enforcement='%s'", spf_sender_domain, dmarc_used_domain, - (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?"yes":"no", - (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?"yes":"no", + sa==DMARC_POLICY_SPF_ALIGNMENT_PASS ?"yes":"no", + da==DMARC_POLICY_DKIM_ALIGNMENT_PASS ?"yes":"no", dmarc_status_text); history_file_status = dmarc_write_history_file(); /* Now get the forensic reporting addresses, if any */ @@ -479,19 +505,16 @@ if (!dmarc_abort && !sender_host_authenticated) } } -/* set some global variables here */ -dmarc_ar_header = dmarc_auth_results_header(from_header, NULL); - /* shut down libopendmarc */ -if ( dmarc_pctx != NULL ) +if (dmarc_pctx) (void) opendmarc_policy_connect_shutdown(dmarc_pctx); -if ( dmarc_disable_verify == FALSE ) +if (!f.dmarc_disable_verify) (void) opendmarc_policy_library_shutdown(&dmarc_ctx); return OK; } -int +static int dmarc_write_history_file() { int history_file_fd; @@ -501,15 +524,18 @@ u_char **rua; /* aggregate report addressees */ uschar *history_buffer = NULL; if (!dmarc_history_file) + { + DEBUG(D_receive) debug_printf("DMARC history file not set\n"); return DMARC_HIST_DISABLED; + } history_file_fd = log_create(dmarc_history_file); if (history_file_fd < 0) -{ + { log_write(0, LOG_MAIN|LOG_PANIC, "failure to create DMARC history file: %s", dmarc_history_file); return DMARC_HIST_FILE_ERR; -} + } /* Generate the contents of the history file */ history_buffer = string_sprintf( @@ -553,8 +579,8 @@ history_buffer = string_sprintf( /* Write the contents to the history file */ DEBUG(D_receive) debug_printf("DMARC logging history data for opendmarc reporting%s\n", - (host_checking || running_in_test_harness) ? " (not really)" : ""); -if (host_checking || running_in_test_harness) + (host_checking || f.running_in_test_harness) ? " (not really)" : ""); +if (host_checking || f.running_in_test_harness) { DEBUG(D_receive) debug_printf("DMARC history data for debugging:\n%s", history_buffer); @@ -575,71 +601,40 @@ else return DMARC_HIST_OK; } + uschar * dmarc_exim_expand_query(int what) { -if (dmarc_disable_verify || !dmarc_pctx) +if (f.dmarc_disable_verify || !dmarc_pctx) return dmarc_exim_expand_defaults(what); -switch(what) - { - case DMARC_VERIFY_STATUS: - return(dmarc_status); - default: - return US""; - } +if (what == DMARC_VERIFY_STATUS) + return dmarc_status; +return US""; } uschar * dmarc_exim_expand_defaults(int what) { -switch(what) - { - case DMARC_VERIFY_STATUS: - return dmarc_disable_verify ? US"off" : US"none"; - default: - return US""; - } +if (what == DMARC_VERIFY_STATUS) + return f.dmarc_disable_verify ? US"off" : US"none"; +return US""; } -uschar * -dmarc_auth_results_header(header_line *from_header, uschar *hostname) -{ -uschar *hdr_tmp = US""; - -/* Allow a server hostname to be passed to this function, but is - * currently unused */ -if (!hostname) - hostname = primary_hostname; -hdr_tmp = string_sprintf("%s %s;", DMARC_AR_HEADER, hostname); - -#if 0 -/* I don't think this belongs here, but left it here commented out - * because it was a lot of work to get working right. */ -if (spf_response != NULL) { - uschar *dmarc_ar_spf = US""; - int sr = 0; - sr = spf_response->result; - dmarc_ar_spf = (sr == SPF_RESULT_NEUTRAL) ? US"neutral" : - (sr == SPF_RESULT_PASS) ? US"pass" : - (sr == SPF_RESULT_FAIL) ? US"fail" : - (sr == SPF_RESULT_SOFTFAIL) ? US"softfail" : - US"none"; - hdr_tmp = string_sprintf("%s spf=%s (%s) smtp.mail=%s;", - hdr_tmp, dmarc_ar_spf_result, - spf_response->header_comment, - expand_string(US"$sender_address") ); -} -#endif -hdr_tmp = string_sprintf("%s dmarc=%s", hdr_tmp, dmarc_pass_fail); -if (header_from_sender) - hdr_tmp = string_sprintf("%s header.from=%s", - hdr_tmp, header_from_sender); -return hdr_tmp; +gstring * +authres_dmarc(gstring * g) +{ +if (f.dmarc_has_been_checked) + { + g = string_append(g, 2, US";\n\tdmarc=", dmarc_pass_fail); + if (header_from_sender) + g = string_append(g, 2, US" header.from=", header_from_sender); + } +return g; } -# endif /* EXPERIMENTAL_SPF */ -#endif /* EXPERIMENTAL_DMARC */ +# endif /* SUPPORT_SPF */ +#endif /* SUPPORT_DMARC */ /* vi: aw ai sw=2 */