X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/db3f7b6972f3b003c0413b78afcfbe295ffe0b97..12fb3842f81bcbd4a4519d5728f2d7e0e3ca1445:/src/src/dmarc.c diff --git a/src/src/dmarc.c b/src/src/dmarc.c index c4edc9159..53c2752ac 100644 --- a/src/src/dmarc.c +++ b/src/src/dmarc.c @@ -1,7 +1,8 @@ /************************************************* * Exim - an Internet mail transport agent * *************************************************/ -/* Experimental DMARC support. +/* DMARC support. + Copyright (c) The Exim Maintainers 2019 - 2022 Copyright (c) Todd Lyons 2012 - 2014 License: GPL */ @@ -11,7 +12,7 @@ /* Code for calling dmarc checks via libopendmarc. Called from acl.c. */ #include "exim.h" -#ifdef EXPERIMENTAL_DMARC +#ifdef SUPPORT_DMARC # if !defined SUPPORT_SPF # error SPF must also be enabled for DMARC # elif defined DISABLE_DKIM @@ -50,21 +51,32 @@ static dmarc_exim_p dmarc_policy_description[] = { { US"reject", DMARC_RECORD_P_REJECT }, { NULL, 0 } }; + + +gstring * +dmarc_version_report(gstring * g) +{ +return string_fmt_append(g, "Library version: dmarc: Compile: %d.%d.%d.%d\n", + (OPENDMARC_LIB_VERSION & 0xff000000) >> 24, (OPENDMARC_LIB_VERSION & 0x00ff0000) >> 16, + (OPENDMARC_LIB_VERSION & 0x0000ff00) >> 8, OPENDMARC_LIB_VERSION & 0x000000ff); +} + + /* Accept an error_block struct, initialize if empty, parse to the - * end, and append the two strings passed to it. Used for adding - * variable amounts of value:pair data to the forensic emails. */ +end, and append the two strings passed to it. Used for adding +variable amounts of value:pair data to the forensic emails. */ static error_block * add_to_eblock(error_block *eblock, uschar *t1, uschar *t2) { error_block *eb = store_malloc(sizeof(error_block)); -if (eblock == NULL) +if (!eblock) eblock = eb; else { /* Find the end of the eblock struct and point it at eb */ error_block *tmp = eblock; - while(tmp->next != NULL) + while(tmp->next) tmp = tmp->next; tmp->next = eb; } @@ -75,8 +87,8 @@ return eblock; } /* dmarc_init sets up a context that can be re-used for several - messages on the same SMTP connection (that come from the - same host with the same HELO string) */ +messages on the same SMTP connection (that come from the +same host with the same HELO string) */ int dmarc_init() @@ -109,15 +121,15 @@ if (libdm_status != DMARC_PARSE_OKAY) opendmarc_policy_status_to_str(libdm_status)); dmarc_abort = TRUE; } -if (!dmarc_tld_file) +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(CS dmarc_tld_file, NULL, NULL, NULL)) { - log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list %s: %d", - dmarc_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) @@ -203,6 +215,118 @@ if ( dmarc_policy == DMARC_POLICY_REJECT && action == DMARC_RESULT_REJECT } } + +/* 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) + { + uschar *record = string_copyn_taint(US rr->data, rr->size, GET_TAINTED); + store_free_dns_answer(dnsa); + return record; + } +store_free_dns_answer(dnsa); +return NULL; +} + + +static int +dmarc_write_history_file() +{ +int history_file_fd; +ssize_t written_len; +int tmp_ans; +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_open_as_exim(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( + "job %s\nreporter %s\nreceived %ld\nipaddr %s\nfrom %s\nmfrom %s\n", + message_id, primary_hostname, time(NULL), sender_host_address, + header_from_sender, expand_string(US"$sender_address_domain")); + +if (spf_response) + history_buffer = string_sprintf("%sspf %d\n", history_buffer, dmarc_spf_ares_result); + /* history_buffer = string_sprintf("%sspf -1\n", history_buffer); */ + +history_buffer = string_sprintf( + "%s%spdomain %s\npolicy %d\n", + history_buffer, dkim_history_buffer, dmarc_used_domain, dmarc_policy); + +if ((rua = opendmarc_policy_fetch_rua(dmarc_pctx, NULL, 0, 1))) + for (tmp_ans = 0; rua[tmp_ans]; tmp_ans++) + history_buffer = string_sprintf("%srua %s\n", history_buffer, rua[tmp_ans]); +else + history_buffer = string_sprintf("%srua -\n", history_buffer); + +opendmarc_policy_fetch_pct(dmarc_pctx, &tmp_ans); +history_buffer = string_sprintf("%spct %d\n", history_buffer, tmp_ans); + +opendmarc_policy_fetch_adkim(dmarc_pctx, &tmp_ans); +history_buffer = string_sprintf("%sadkim %d\n", history_buffer, tmp_ans); + +opendmarc_policy_fetch_aspf(dmarc_pctx, &tmp_ans); +history_buffer = string_sprintf("%saspf %d\n", history_buffer, tmp_ans); + +opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans); +history_buffer = string_sprintf("%sp %d\n", history_buffer, tmp_ans); + +opendmarc_policy_fetch_sp(dmarc_pctx, &tmp_ans); +history_buffer = string_sprintf("%ssp %d\n", history_buffer, tmp_ans); + +history_buffer = string_sprintf( + "%salign_dkim %d\nalign_spf %d\naction %d\n", + history_buffer, da, sa, action); + +/* Write the contents to the history file */ +DEBUG(D_receive) + debug_printf("DMARC logging history data for opendmarc reporting%s\n", + (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); + } +else + { + written_len = write_to_fd_buf(history_file_fd, + history_buffer, + Ustrlen(history_buffer)); + if (written_len == 0) + { + log_write(0, LOG_MAIN|LOG_PANIC, "failure to write to DMARC history file: %s", + dmarc_history_file); + return DMARC_HIST_WRITE_ERR; + } + (void)close(history_file_fd); + } +return DMARC_HIST_OK; +} + + /* 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. */ @@ -214,6 +338,7 @@ 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 = dkim_signatures; +uschar * rr; BOOL has_dmarc_record = TRUE; u_char **ruf; /* forensic report addressees, if called for */ @@ -335,7 +460,12 @@ if (!dmarc_abort && !sender_host_authenticated) vs == PDKIM_VERIFY_INVALID ? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL : DMARC_POLICY_DKIM_OUTCOME_NONE; libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, US sig->domain, - dkim_result, US""); +/* The opendmarc project broke its API in a way we can't detect * easily. + * The EDITME provides a DMARC_API variable */ +#if DMARC_API >= 100400 + sig->selector, +#endif + dkim_result, US""); DEBUG(D_receive) debug_printf("DMARC adding DKIM sender domain = %s\n", sig->domain); if (libdm_status != DMARC_PARSE_OKAY) @@ -358,7 +488,15 @@ 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: @@ -398,11 +536,11 @@ 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. */ - dmarc_domain = US calloc(DMARC_MAXHOSTNAMELEN, sizeof(uschar)); + dmarc_domain = store_get(DMARC_MAXHOSTNAMELEN, GET_TAINTED); 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, @@ -485,94 +623,6 @@ if (!f.dmarc_disable_verify) return OK; } -static int -dmarc_write_history_file() -{ -int history_file_fd; -ssize_t written_len; -int tmp_ans; -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( - "job %s\nreporter %s\nreceived %ld\nipaddr %s\nfrom %s\nmfrom %s\n", - message_id, primary_hostname, time(NULL), sender_host_address, - header_from_sender, expand_string(US"$sender_address_domain")); - -if (spf_response) - history_buffer = string_sprintf("%sspf %d\n", history_buffer, dmarc_spf_ares_result); - /* history_buffer = string_sprintf("%sspf -1\n", history_buffer); */ - -history_buffer = string_sprintf( - "%s%spdomain %s\npolicy %d\n", - history_buffer, dkim_history_buffer, dmarc_used_domain, dmarc_policy); - -if ((rua = opendmarc_policy_fetch_rua(dmarc_pctx, NULL, 0, 1))) - for (tmp_ans = 0; rua[tmp_ans]; tmp_ans++) - history_buffer = string_sprintf("%srua %s\n", history_buffer, rua[tmp_ans]); -else - history_buffer = string_sprintf("%srua -\n", history_buffer); - -opendmarc_policy_fetch_pct(dmarc_pctx, &tmp_ans); -history_buffer = string_sprintf("%spct %d\n", history_buffer, tmp_ans); - -opendmarc_policy_fetch_adkim(dmarc_pctx, &tmp_ans); -history_buffer = string_sprintf("%sadkim %d\n", history_buffer, tmp_ans); - -opendmarc_policy_fetch_aspf(dmarc_pctx, &tmp_ans); -history_buffer = string_sprintf("%saspf %d\n", history_buffer, tmp_ans); - -opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans); -history_buffer = string_sprintf("%sp %d\n", history_buffer, tmp_ans); - -opendmarc_policy_fetch_sp(dmarc_pctx, &tmp_ans); -history_buffer = string_sprintf("%ssp %d\n", history_buffer, tmp_ans); - -history_buffer = string_sprintf( - "%salign_dkim %d\nalign_spf %d\naction %d\n", - history_buffer, da, sa, action); - -/* Write the contents to the history file */ -DEBUG(D_receive) - debug_printf("DMARC logging history data for opendmarc reporting%s\n", - (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); - } -else - { - written_len = write_to_fd_buf(history_file_fd, - history_buffer, - Ustrlen(history_buffer)); - if (written_len == 0) - { - log_write(0, LOG_MAIN|LOG_PANIC, "failure to write to DMARC history file: %s", - dmarc_history_file); - return DMARC_HIST_WRITE_ERR; - } - (void)close(history_file_fd); - } -return DMARC_HIST_OK; -} - - uschar * dmarc_exim_expand_query(int what) { @@ -606,6 +656,6 @@ return g; } # endif /* SUPPORT_SPF */ -#endif /* EXPERIMENTAL_DMARC */ +#endif /* SUPPORT_DMARC */ /* vi: aw ai sw=2 */