/* $Cambridge: exim/src/src/acl.c,v 1.51 2005/11/14 16:09:54 ph10 Exp $ */ /************************************************* * Exim - an Internet mail transport agent * *************************************************/ /* Copyright (c) University of Cambridge 1995 - 2005 */ /* See the file NOTICE for conditions of use and distribution. */ /* Code for handling Access Control Lists (ACLs) */ #include "exim.h" /* Default callout timeout */ #define CALLOUT_TIMEOUT_DEFAULT 30 /* ACL verb codes - keep in step with the table of verbs that follows */ enum { ACL_ACCEPT, ACL_DEFER, ACL_DENY, ACL_DISCARD, ACL_DROP, ACL_REQUIRE, ACL_WARN }; /* ACL verbs */ static uschar *verbs[] = { US"accept", US"defer", US"deny", US"discard", US"drop", US"require", US"warn" }; /* For each verb, the condition for which "message" is used */ static int msgcond[] = { FAIL, OK, OK, FAIL, OK, FAIL, OK }; /* ACL condition and modifier codes - keep in step with the table that follows. */ enum { ACLC_ACL, ACLC_AUTHENTICATED, #ifdef EXPERIMENTAL_BRIGHTMAIL ACLC_BMI_OPTIN, #endif ACLC_CONDITION, ACLC_CONTROL, #ifdef WITH_CONTENT_SCAN ACLC_DECODE, #endif ACLC_DELAY, #ifdef WITH_OLD_DEMIME ACLC_DEMIME, #endif #ifdef EXPERIMENTAL_DOMAINKEYS ACLC_DK_DOMAIN_SOURCE, ACLC_DK_POLICY, ACLC_DK_SENDER_DOMAINS, ACLC_DK_SENDER_LOCAL_PARTS, ACLC_DK_SENDERS, ACLC_DK_STATUS, #endif ACLC_DNSLISTS, ACLC_DOMAINS, ACLC_ENCRYPTED, ACLC_ENDPASS, ACLC_HOSTS, ACLC_LOCAL_PARTS, ACLC_LOG_MESSAGE, ACLC_LOGWRITE, #ifdef WITH_CONTENT_SCAN ACLC_MALWARE, #endif ACLC_MESSAGE, #ifdef WITH_CONTENT_SCAN ACLC_MIME_REGEX, #endif ACLC_RATELIMIT, ACLC_RECIPIENTS, #ifdef WITH_CONTENT_SCAN ACLC_REGEX, #endif ACLC_SENDER_DOMAINS, ACLC_SENDERS, ACLC_SET, #ifdef WITH_CONTENT_SCAN ACLC_SPAM, #endif #ifdef EXPERIMENTAL_SPF ACLC_SPF, #endif ACLC_VERIFY }; /* ACL conditions/modifiers: "delay", "control", "endpass", "message", "log_message", "logwrite", and "set" are modifiers that look like conditions but always return TRUE. They are used for their side effects. */ static uschar *conditions[] = { US"acl", US"authenticated", #ifdef EXPERIMENTAL_BRIGHTMAIL US"bmi_optin", #endif US"condition", US"control", #ifdef WITH_CONTENT_SCAN US"decode", #endif US"delay", #ifdef WITH_OLD_DEMIME US"demime", #endif #ifdef EXPERIMENTAL_DOMAINKEYS US"dk_domain_source", US"dk_policy", US"dk_sender_domains", US"dk_sender_local_parts", US"dk_senders", US"dk_status", #endif US"dnslists", US"domains", US"encrypted", US"endpass", US"hosts", US"local_parts", US"log_message", US"logwrite", #ifdef WITH_CONTENT_SCAN US"malware", #endif US"message", #ifdef WITH_CONTENT_SCAN US"mime_regex", #endif US"ratelimit", US"recipients", #ifdef WITH_CONTENT_SCAN US"regex", #endif US"sender_domains", US"senders", US"set", #ifdef WITH_CONTENT_SCAN US"spam", #endif #ifdef EXPERIMENTAL_SPF US"spf", #endif US"verify" }; /* Return values from decode_control(); keep in step with the table of names that follows! */ enum { #ifdef EXPERIMENTAL_BRIGHTMAIL CONTROL_BMI_RUN, #endif #ifdef EXPERIMENTAL_DOMAINKEYS CONTROL_DK_VERIFY, #endif CONTROL_ERROR, CONTROL_CASEFUL_LOCAL_PART, CONTROL_CASELOWER_LOCAL_PART, CONTROL_ENFORCE_SYNC, CONTROL_NO_ENFORCE_SYNC, CONTROL_FREEZE, CONTROL_QUEUE_ONLY, CONTROL_SUBMISSION, CONTROL_SUPPRESS_LOCAL_FIXUPS, #ifdef WITH_CONTENT_SCAN CONTROL_NO_MBOX_UNSPOOL, #endif CONTROL_FAKEDEFER, CONTROL_FAKEREJECT, CONTROL_NO_MULTILINE }; /* ACL control names; keep in step with the table above! This list is used for turning ids into names. The actual list of recognized names is in the variable control_def controls_list[] below. The fact that there are two lists is a mess and should be tidied up. */ static uschar *controls[] = { #ifdef EXPERIMENTAL_BRIGHTMAIL US"bmi_run", #endif #ifdef EXPERIMENTAL_DOMAINKEYS US"dk_verify", #endif US"error", US"caseful_local_part", US"caselower_local_part", US"enforce_sync", US"no_enforce_sync", US"freeze", US"queue_only", US"submission", US"suppress_local_fixups", #ifdef WITH_CONTENT_SCAN US"no_mbox_unspool", #endif US"no_multiline"}; /* Flags to indicate for which conditions /modifiers a string expansion is done at the outer level. In the other cases, expansion already occurs in the checking functions. */ static uschar cond_expand_at_top[] = { TRUE, /* acl */ FALSE, /* authenticated */ #ifdef EXPERIMENTAL_BRIGHTMAIL TRUE, /* bmi_optin */ #endif TRUE, /* condition */ TRUE, /* control */ #ifdef WITH_CONTENT_SCAN TRUE, /* decode */ #endif TRUE, /* delay */ #ifdef WITH_OLD_DEMIME TRUE, /* demime */ #endif #ifdef EXPERIMENTAL_DOMAINKEYS TRUE, /* dk_domain_source */ TRUE, /* dk_policy */ TRUE, /* dk_sender_domains */ TRUE, /* dk_sender_local_parts */ TRUE, /* dk_senders */ TRUE, /* dk_status */ #endif TRUE, /* dnslists */ FALSE, /* domains */ FALSE, /* encrypted */ TRUE, /* endpass */ FALSE, /* hosts */ FALSE, /* local_parts */ TRUE, /* log_message */ TRUE, /* logwrite */ #ifdef WITH_CONTENT_SCAN TRUE, /* malware */ #endif TRUE, /* message */ #ifdef WITH_CONTENT_SCAN TRUE, /* mime_regex */ #endif TRUE, /* ratelimit */ FALSE, /* recipients */ #ifdef WITH_CONTENT_SCAN TRUE, /* regex */ #endif FALSE, /* sender_domains */ FALSE, /* senders */ TRUE, /* set */ #ifdef WITH_CONTENT_SCAN TRUE, /* spam */ #endif #ifdef EXPERIMENTAL_SPF TRUE, /* spf */ #endif TRUE /* verify */ }; /* Flags to identify the modifiers */ static uschar cond_modifiers[] = { FALSE, /* acl */ FALSE, /* authenticated */ #ifdef EXPERIMENTAL_BRIGHTMAIL TRUE, /* bmi_optin */ #endif FALSE, /* condition */ TRUE, /* control */ #ifdef WITH_CONTENT_SCAN FALSE, /* decode */ #endif TRUE, /* delay */ #ifdef WITH_OLD_DEMIME FALSE, /* demime */ #endif #ifdef EXPERIMENTAL_DOMAINKEYS FALSE, /* dk_domain_source */ FALSE, /* dk_policy */ FALSE, /* dk_sender_domains */ FALSE, /* dk_sender_local_parts */ FALSE, /* dk_senders */ FALSE, /* dk_status */ #endif FALSE, /* dnslists */ FALSE, /* domains */ FALSE, /* encrypted */ TRUE, /* endpass */ FALSE, /* hosts */ FALSE, /* local_parts */ TRUE, /* log_message */ TRUE, /* logwrite */ #ifdef WITH_CONTENT_SCAN FALSE, /* malware */ #endif TRUE, /* message */ #ifdef WITH_CONTENT_SCAN FALSE, /* mime_regex */ #endif FALSE, /* ratelimit */ FALSE, /* recipients */ #ifdef WITH_CONTENT_SCAN FALSE, /* regex */ #endif FALSE, /* sender_domains */ FALSE, /* senders */ TRUE, /* set */ #ifdef WITH_CONTENT_SCAN FALSE, /* spam */ #endif #ifdef EXPERIMENTAL_SPF FALSE, /* spf */ #endif FALSE /* verify */ }; /* Bit map vector of which conditions are not allowed at certain times. For each condition, there's a bitmap of dis-allowed times. For some, it is easier to specify the negation of a small number of allowed times. */ static unsigned int cond_forbids[] = { 0, /* acl */ (1<verb != ACL_ACCEPT && this->verb != ACL_DISCARD) { *error = string_sprintf("ACL error: \"%s\" is not allowed with \"%s\"", conditions[c], verbs[this->verb]); return NULL; } cond = store_get(sizeof(acl_condition_block)); cond->next = NULL; cond->type = c; cond->u.negated = negated; *condp = cond; condp = &(cond->next); /* The "set" modifier is different in that its argument is "name=value" rather than just a value, and we can check the validity of the name, which gives us a variable number to insert into the data block. */ if (c == ACLC_SET) { if (Ustrncmp(s, "acl_", 4) != 0 || (s[4] != 'c' && s[4] != 'm') || !isdigit(s[5]) || (!isspace(s[6]) && s[6] != '=')) { *error = string_sprintf("unrecognized name after \"set\" in ACL " "modifier \"set %s\"", s); return NULL; } cond->u.varnumber = s[5] - '0'; if (s[4] == 'm') cond->u.varnumber += ACL_C_MAX; s += 6; while (isspace(*s)) s++; } /* For "set", we are now positioned for the data. For the others, only "endpass" has no data */ if (c != ACLC_ENDPASS) { if (*s++ != '=') { *error = string_sprintf("\"=\" missing after ACL \"%s\" %s", name, cond_modifiers[c]? US"modifier" : US"condition"); return NULL; } while (isspace(*s)) s++; cond->arg = string_copy(s); } } return yield; } /************************************************* * Handle warnings * *************************************************/ /* This function is called when a WARN verb's conditions are true. It adds to the message's headers, and/or writes information to the log. In each case, this only happens once (per message for headers, per connection for log). Arguments: where ACL_WHERE_xxxx indicating which ACL this is user_message message for adding to headers log_message message for logging, if different Returns: nothing */ static void acl_warn(int where, uschar *user_message, uschar *log_message) { int hlen; if (log_message != NULL && log_message != user_message) { uschar *text; string_item *logged; text = string_sprintf("%s Warning: %s", host_and_ident(TRUE), string_printing(log_message)); /* If a sender verification has failed, and the log message is "sender verify failed", add the failure message. */ if (sender_verified_failed != NULL && sender_verified_failed->message != NULL && strcmpic(log_message, US"sender verify failed") == 0) text = string_sprintf("%s: %s", text, sender_verified_failed->message); /* Search previously logged warnings. They are kept in malloc store so they can be freed at the start of a new message. */ for (logged = acl_warn_logged; logged != NULL; logged = logged->next) if (Ustrcmp(logged->text, text) == 0) break; if (logged == NULL) { int length = Ustrlen(text) + 1; log_write(0, LOG_MAIN, "%s", text); logged = store_malloc(sizeof(string_item) + length); logged->text = (uschar *)logged + sizeof(string_item); memcpy(logged->text, text, length); logged->next = acl_warn_logged; acl_warn_logged = logged; } } /* If there's no user message, we are done. */ if (user_message == NULL) return; /* If this isn't a message ACL, we can't do anything with a user message. Log an error. */ if (where > ACL_WHERE_NOTSMTP) { log_write(0, LOG_MAIN|LOG_PANIC, "ACL \"warn\" with \"message\" setting " "found in a non-message (%s) ACL: cannot specify header lines here: " "message ignored", acl_wherenames[where]); return; } /* Treat the user message as a sequence of one or more header lines. */ hlen = Ustrlen(user_message); if (hlen > 0) { uschar *text, *p, *q; /* Add a final newline if not present */ text = ((user_message)[hlen-1] == '\n')? user_message : string_sprintf("%s\n", user_message); /* Loop for multiple header lines, taking care about continuations */ for (p = q = text; *p != 0; ) { uschar *s; int newtype = htype_add_bot; header_line **hptr = &acl_warn_headers; /* Find next header line within the string */ for (;;) { q = Ustrchr(q, '\n'); if (*(++q) != ' ' && *q != '\t') break; } /* If the line starts with a colon, interpret the instruction for where to add it. This temporarily sets up a new type. */ if (*p == ':') { if (strncmpic(p, US":after_received:", 16) == 0) { newtype = htype_add_rec; p += 16; } else if (strncmpic(p, US":at_start_rfc:", 14) == 0) { newtype = htype_add_rfc; p += 14; } else if (strncmpic(p, US":at_start:", 10) == 0) { newtype = htype_add_top; p += 10; } else if (strncmpic(p, US":at_end:", 8) == 0) { newtype = htype_add_bot; p += 8; } while (*p == ' ' || *p == '\t') p++; } /* See if this line starts with a header name, and if not, add X-ACL-Warn: to the front of it. */ for (s = p; s < q - 1; s++) { if (*s == ':' || !isgraph(*s)) break; } s = string_sprintf("%s%.*s", (*s == ':')? "" : "X-ACL-Warn: ", q - p, p); hlen = Ustrlen(s); /* See if this line has already been added */ while (*hptr != NULL) { if (Ustrncmp((*hptr)->text, s, hlen) == 0) break; hptr = &((*hptr)->next); } /* Add if not previously present */ if (*hptr == NULL) { header_line *h = store_get(sizeof(header_line)); h->text = s; h->next = NULL; h->type = newtype; h->slen = hlen; *hptr = h; hptr = &(h->next); } /* Advance for next header line within the string */ p = q; } } } /************************************************* * Verify and check reverse DNS * *************************************************/ /* Called from acl_verify() below. We look up the host name(s) of the client IP address if this has not yet been done. The host_name_lookup() function checks that one of these names resolves to an address list that contains the client IP address, so we don't actually have to do the check here. Arguments: user_msgptr pointer for user message log_msgptr pointer for log message Returns: OK verification condition succeeded FAIL verification failed DEFER there was a problem verifying */ static int acl_verify_reverse(uschar **user_msgptr, uschar **log_msgptr) { int rc; user_msgptr = user_msgptr; /* stop compiler warning */ /* Previous success */ if (sender_host_name != NULL) return OK; /* Previous failure */ if (host_lookup_failed) { *log_msgptr = string_sprintf("host lookup failed%s", host_lookup_msg); return FAIL; } /* Need to do a lookup */ HDEBUG(D_acl) debug_printf("looking up host name to force name/address consistency check\n"); if ((rc = host_name_lookup()) != OK) { *log_msgptr = (rc == DEFER)? US"host lookup deferred for reverse lookup check" : string_sprintf("host lookup failed for reverse lookup check%s", host_lookup_msg); return rc; /* DEFER or FAIL */ } host_build_sender_fullhost(); return OK; } /************************************************* * Check client IP address matches CSA target * *************************************************/ /* Called from acl_verify_csa() below. This routine scans a section of a DNS response for address records belonging to the CSA target hostname. The section is specified by the reset argument, either RESET_ADDITIONAL or RESET_ANSWERS. If one of the addresses matches the client's IP address, then the client is authorized by CSA. If there are target IP addresses but none of them match then the client is using an unauthorized IP address. If there are no target IP addresses then the client cannot be using an authorized IP address. (This is an odd configuration - why didn't the SRV record have a weight of 1 instead?) Arguments: dnsa the DNS answer block dnss a DNS scan block for us to use reset option specifing what portion to scan, as described above target the target hostname to use for matching RR names Returns: CSA_OK successfully authorized CSA_FAIL_MISMATCH addresses found but none matched CSA_FAIL_NOADDR no target addresses found */ static int acl_verify_csa_address(dns_answer *dnsa, dns_scan *dnss, int reset, uschar *target) { dns_record *rr; dns_address *da; BOOL target_found = FALSE; for (rr = dns_next_rr(dnsa, dnss, reset); rr != NULL; rr = dns_next_rr(dnsa, dnss, RESET_NEXT)) { /* Check this is an address RR for the target hostname. */ if (rr->type != T_A #if HAVE_IPV6 && rr->type != T_AAAA #ifdef SUPPORT_A6 && rr->type != T_A6 #endif #endif ) continue; if (strcmpic(target, rr->name) != 0) continue; target_found = TRUE; /* Turn the target address RR into a list of textual IP addresses and scan the list. There may be more than one if it is an A6 RR. */ for (da = dns_address_from_rr(dnsa, rr); da != NULL; da = da->next) { /* If the client IP address matches the target IP address, it's good! */ DEBUG(D_acl) debug_printf("CSA target address is %s\n", da->address); if (strcmpic(sender_host_address, da->address) == 0) return CSA_OK; } } /* If we found some target addresses but none of them matched, the client is using an unauthorized IP address, otherwise the target has no authorized IP addresses. */ if (target_found) return CSA_FAIL_MISMATCH; else return CSA_FAIL_NOADDR; } /************************************************* * Verify Client SMTP Authorization * *************************************************/ /* Called from acl_verify() below. This routine calls dns_lookup_special() to find the CSA SRV record corresponding to the domain argument, or $sender_helo_name if no argument is provided. It then checks that the client is authorized, and that its IP address corresponds to the SRV target's address by calling acl_verify_csa_address() above. The address should have been returned in the DNS response's ADDITIONAL section, but if not we perform another DNS lookup to get it. Arguments: domain pointer to optional parameter following verify = csa Returns: CSA_UNKNOWN no valid CSA record found CSA_OK successfully authorized CSA_FAIL_* client is definitely not authorized CSA_DEFER_* there was a DNS problem */ static int acl_verify_csa(uschar *domain) { tree_node *t; uschar *found, *p; int priority, weight, port; dns_answer dnsa; dns_scan dnss; dns_record *rr; int rc, type; uschar target[256]; /* Work out the domain we are using for the CSA lookup. The default is the client's HELO domain. If the client has not said HELO, use its IP address instead. If it's a local client (exim -bs), CSA isn't applicable. */ while (isspace(*domain) && *domain != '\0') ++domain; if (*domain == '\0') domain = sender_helo_name; if (domain == NULL) domain = sender_host_address; if (sender_host_address == NULL) return CSA_UNKNOWN; /* If we have an address literal, strip off the framing ready for turning it into a domain. The framing consists of matched square brackets possibly containing a keyword and a colon before the actual IP address. */ if (domain[0] == '[') { uschar *start = Ustrchr(domain, ':'); if (start == NULL) start = domain; domain = string_copyn(start + 1, Ustrlen(start) - 2); } /* Turn domains that look like bare IP addresses into domains in the reverse DNS. This code also deals with address literals and $sender_host_address. It's not quite kosher to treat bare domains such as EHLO 192.0.2.57 the same as address literals, but it's probably the most friendly thing to do. This is an extension to CSA, so we allow it to be turned off for proper conformance. */ if (string_is_ip_address(domain, NULL)) { if (!dns_csa_use_reverse) return CSA_UNKNOWN; dns_build_reverse(domain, target); domain = target; } /* Find out if we've already done the CSA check for this domain. If we have, return the same result again. Otherwise build a new cached result structure for this domain. The name is filled in now, and the value is filled in when we return from this function. */ t = tree_search(csa_cache, domain); if (t != NULL) return t->data.val; t = store_get_perm(sizeof(tree_node) + Ustrlen(domain)); Ustrcpy(t->name, domain); (void)tree_insertnode(&csa_cache, t); /* Now we are ready to do the actual DNS lookup(s). */ found = domain; switch (dns_special_lookup(&dnsa, domain, T_CSA, &found)) { /* If something bad happened (most commonly DNS_AGAIN), defer. */ default: return t->data.val = CSA_DEFER_SRV; /* If we found nothing, the client's authorization is unknown. */ case DNS_NOMATCH: case DNS_NODATA: return t->data.val = CSA_UNKNOWN; /* We got something! Go on to look at the reply in more detail. */ case DNS_SUCCEED: break; } /* Scan the reply for well-formed CSA SRV records. */ for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS); rr != NULL; rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT)) { if (rr->type != T_SRV) continue; /* Extract the numerical SRV fields (p is incremented) */ p = rr->data; GETSHORT(priority, p); GETSHORT(weight, p); GETSHORT(port, p); DEBUG(D_acl) debug_printf("CSA priority=%d weight=%d port=%d\n", priority, weight, port); /* Check the CSA version number */ if (priority != 1) continue; /* If the domain does not have a CSA SRV record of its own (i.e. the domain found by dns_special_lookup() is a parent of the one we asked for), we check the subdomain assertions in the port field. At the moment there's only one assertion: legitimate SMTP clients are all explicitly authorized with CSA SRV records of their own. */ if (found != domain) { if (port & 1) return t->data.val = CSA_FAIL_EXPLICIT; else return t->data.val = CSA_UNKNOWN; } /* This CSA SRV record refers directly to our domain, so we check the value in the weight field to work out the domain's authorization. 0 and 1 are unauthorized; 3 means the client is authorized but we can't check the IP address in order to authenticate it, so we treat it as unknown; values greater than 3 are undefined. */ if (weight < 2) return t->data.val = CSA_FAIL_DOMAIN; if (weight > 2) continue; /* Weight == 2, which means the domain is authorized. We must check that the client's IP address is listed as one of the SRV target addresses. Save the target hostname then break to scan the additional data for its addresses. */ (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, p, (DN_EXPAND_ARG4_TYPE)target, sizeof(target)); DEBUG(D_acl) debug_printf("CSA target is %s\n", target); break; } /* If we didn't break the loop then no appropriate records were found. */ if (rr == NULL) return t->data.val = CSA_UNKNOWN; /* Do not check addresses if the target is ".", in accordance with RFC 2782. A target of "." indicates there are no valid addresses, so the client cannot be authorized. (This is an odd configuration because weight=2 target=. is equivalent to weight=1, but we check for it in order to keep load off the root name servers.) Note that dn_expand() turns "." into "". */ if (Ustrcmp(target, "") == 0) return t->data.val = CSA_FAIL_NOADDR; /* Scan the additional section of the CSA SRV reply for addresses belonging to the target. If the name server didn't return any additional data (e.g. because it does not fully support SRV records), we need to do another lookup to obtain the target addresses; otherwise we have a definitive result. */ rc = acl_verify_csa_address(&dnsa, &dnss, RESET_ADDITIONAL, target); if (rc != CSA_FAIL_NOADDR) return t->data.val = rc; /* The DNS lookup type corresponds to the IP version used by the client. */ #if HAVE_IPV6 if (Ustrchr(sender_host_address, ':') != NULL) type = T_AAAA; else #endif /* HAVE_IPV6 */ type = T_A; #if HAVE_IPV6 && defined(SUPPORT_A6) DNS_LOOKUP_AGAIN: #endif switch (dns_lookup(&dnsa, target, type, NULL)) { /* If something bad happened (most commonly DNS_AGAIN), defer. */ default: return t->data.val = CSA_DEFER_ADDR; /* If the query succeeded, scan the addresses and return the result. */ case DNS_SUCCEED: rc = acl_verify_csa_address(&dnsa, &dnss, RESET_ANSWERS, target); if (rc != CSA_FAIL_NOADDR) return t->data.val = rc; /* else fall through */ /* If the target has no IP addresses, the client cannot have an authorized IP address. However, if the target site uses A6 records (not AAAA records) we have to do yet another lookup in order to check them. */ case DNS_NOMATCH: case DNS_NODATA: #if HAVE_IPV6 && defined(SUPPORT_A6) if (type == T_AAAA) { type = T_A6; goto DNS_LOOKUP_AGAIN; } #endif return t->data.val = CSA_FAIL_NOADDR; } } /************************************************* * Handle verification (address & other) * *************************************************/ /* This function implements the "verify" condition. It is called when encountered in any ACL, because some tests are almost always permitted. Some just don't make sense, and always fail (for example, an attempt to test a host lookup for a non-TCP/IP message). Others are restricted to certain ACLs. Arguments: where where called from addr the recipient address that the ACL is handling, or NULL arg the argument of "verify" user_msgptr pointer for user message log_msgptr pointer for log message basic_errno where to put verify errno Returns: OK verification condition succeeded FAIL verification failed DEFER there was a problem verifying ERROR syntax error */ static int acl_verify(int where, address_item *addr, uschar *arg, uschar **user_msgptr, uschar **log_msgptr, int *basic_errno) { int sep = '/'; int callout = -1; int callout_overall = -1; int callout_connect = -1; int verify_options = 0; int rc; BOOL verify_header_sender = FALSE; BOOL defer_ok = FALSE; BOOL callout_defer_ok = FALSE; BOOL no_details = FALSE; BOOL success_on_redirect = FALSE; address_item *sender_vaddr = NULL; uschar *verify_sender_address = NULL; uschar *pm_mailfrom = NULL; uschar *se_mailfrom = NULL; /* Some of the verify items have slash-separated options; some do not. Diagnose an error if options are given for items that don't expect them. This code has now got very message. Refactoring to use a table would be a good idea one day. */ uschar *slash = Ustrchr(arg, '/'); uschar *list = arg; uschar *ss = string_nextinlist(&list, &sep, big_buffer, big_buffer_size); if (ss == NULL) goto BAD_VERIFY; /* Handle name/address consistency verification in a separate function. */ if (strcmpic(ss, US"reverse_host_lookup") == 0) { if (slash != NULL) goto NO_OPTIONS; if (sender_host_address == NULL) return OK; return acl_verify_reverse(user_msgptr, log_msgptr); } /* TLS certificate verification is done at STARTTLS time; here we just test whether it was successful or not. (This is for optional verification; for mandatory verification, the connection doesn't last this long.) */ if (strcmpic(ss, US"certificate") == 0) { if (slash != NULL) goto NO_OPTIONS; if (tls_certificate_verified) return OK; *user_msgptr = US"no verified certificate"; return FAIL; } /* We can test the result of optional HELO verification that might have occurred earlier. If not, we can attempt the verification now. */ if (strcmpic(ss, US"helo") == 0) { if (slash != NULL) goto NO_OPTIONS; if (!helo_verified && !helo_verify_failed) smtp_verify_helo(); return helo_verified? OK : FAIL; } /* Do Client SMTP Authorization checks in a separate function, and turn the result code into user-friendly strings. */ if (strcmpic(ss, US"csa") == 0) { rc = acl_verify_csa(list); *log_msgptr = *user_msgptr = string_sprintf("client SMTP authorization %s", csa_reason_string[rc]); csa_status = csa_status_string[rc]; DEBUG(D_acl) debug_printf("CSA result %s\n", csa_status); return csa_return_code[rc]; } /* Check that all relevant header lines have the correct syntax. If there is a syntax error, we return details of the error to the sender if configured to send out full details. (But a "message" setting on the ACL can override, as always). */ if (strcmpic(ss, US"header_syntax") == 0) { if (slash != NULL) goto NO_OPTIONS; if (where != ACL_WHERE_DATA && where != ACL_WHERE_NOTSMTP) goto WRONG_ACL; rc = verify_check_headers(log_msgptr); if (rc != OK && smtp_return_error_details && *log_msgptr != NULL) *user_msgptr = string_sprintf("Rejected after DATA: %s", *log_msgptr); return rc; } /* Check that no recipient of this message is "blind", that is, every envelope recipient must be mentioned in either To: or Cc:. */ if (strcmpic(ss, US"not_blind") == 0) { if (slash != NULL) goto NO_OPTIONS; if (where != ACL_WHERE_DATA && where != ACL_WHERE_NOTSMTP) goto WRONG_ACL; rc = verify_check_notblind(); if (rc != OK) { *log_msgptr = string_sprintf("bcc recipient detected"); if (smtp_return_error_details) *user_msgptr = string_sprintf("Rejected after DATA: %s", *log_msgptr); } return rc; } /* The remaining verification tests check recipient and sender addresses, either from the envelope or from the header. There are a number of slash-separated options that are common to all of them. */ /* Check that there is at least one verifiable sender address in the relevant header lines. This can be followed by callout and defer options, just like sender and recipient. */ if (strcmpic(ss, US"header_sender") == 0) { if (where != ACL_WHERE_DATA && where != ACL_WHERE_NOTSMTP) goto WRONG_ACL; verify_header_sender = TRUE; } /* Otherwise, first item in verify argument must be "sender" or "recipient". In the case of a sender, this can optionally be followed by an address to use in place of the actual sender (rare special-case requirement). */ else if (strncmpic(ss, US"sender", 6) == 0) { uschar *s = ss + 6; if (where > ACL_WHERE_NOTSMTP) { *log_msgptr = string_sprintf("cannot verify sender in ACL for %s " "(only possible for MAIL, RCPT, PREDATA, or DATA)", acl_wherenames[where]); return ERROR; } if (*s == 0) verify_sender_address = sender_address; else { while (isspace(*s)) s++; if (*s++ != '=') goto BAD_VERIFY; while (isspace(*s)) s++; verify_sender_address = string_copy(s); } } else { if (strcmpic(ss, US"recipient") != 0) goto BAD_VERIFY; if (addr == NULL) { *log_msgptr = string_sprintf("cannot verify recipient in ACL for %s " "(only possible for RCPT)", acl_wherenames[where]); return ERROR; } } /* Remaining items are optional; they apply to sender and recipient verification, including "header sender" verification. */ while ((ss = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)) != NULL) { if (strcmpic(ss, US"defer_ok") == 0) defer_ok = TRUE; else if (strcmpic(ss, US"no_details") == 0) no_details = TRUE; else if (strcmpic(ss, US"success_on_redirect") == 0) success_on_redirect = TRUE; /* These two old options are left for backwards compatibility */ else if (strcmpic(ss, US"callout_defer_ok") == 0) { callout_defer_ok = TRUE; if (callout == -1) callout = CALLOUT_TIMEOUT_DEFAULT; } else if (strcmpic(ss, US"check_postmaster") == 0) { pm_mailfrom = US""; if (callout == -1) callout = CALLOUT_TIMEOUT_DEFAULT; } /* The callout option has a number of sub-options, comma separated */ else if (strncmpic(ss, US"callout", 7) == 0) { callout = CALLOUT_TIMEOUT_DEFAULT; ss += 7; if (*ss != 0) { while (isspace(*ss)) ss++; if (*ss++ == '=') { int optsep = ','; uschar *opt; uschar buffer[256]; while (isspace(*ss)) ss++; /* This callout option handling code has become a mess as new options have been added in an ad hoc manner. It should be tidied up into some kind of table-driven thing. */ while ((opt = string_nextinlist(&ss, &optsep, buffer, sizeof(buffer))) != NULL) { if (strcmpic(opt, US"defer_ok") == 0) callout_defer_ok = TRUE; else if (strcmpic(opt, US"no_cache") == 0) verify_options |= vopt_callout_no_cache; else if (strcmpic(opt, US"random") == 0) verify_options |= vopt_callout_random; else if (strcmpic(opt, US"use_sender") == 0) verify_options |= vopt_callout_recipsender; else if (strcmpic(opt, US"use_postmaster") == 0) verify_options |= vopt_callout_recippmaster; else if (strcmpic(opt, US"postmaster") == 0) pm_mailfrom = US""; else if (strcmpic(opt, US"fullpostmaster") == 0) { pm_mailfrom = US""; verify_options |= vopt_callout_fullpm; } else if (strncmpic(opt, US"mailfrom", 8) == 0) { if (!verify_header_sender) { *log_msgptr = string_sprintf("\"mailfrom\" is allowed as a " "callout option only for verify=header_sender (detected in ACL " "condition \"%s\")", arg); return ERROR; } opt += 8; while (isspace(*opt)) opt++; if (*opt++ != '=') { *log_msgptr = string_sprintf("'=' expected after " "\"mailfrom\" in ACL condition \"%s\"", arg); return ERROR; } while (isspace(*opt)) opt++; se_mailfrom = string_copy(opt); } else if (strncmpic(opt, US"postmaster_mailfrom", 19) == 0) { opt += 19; while (isspace(*opt)) opt++; if (*opt++ != '=') { *log_msgptr = string_sprintf("'=' expected after " "\"postmaster_mailfrom\" in ACL condition \"%s\"", arg); return ERROR; } while (isspace(*opt)) opt++; pm_mailfrom = string_copy(opt); } else if (strncmpic(opt, US"maxwait", 7) == 0) { opt += 7; while (isspace(*opt)) opt++; if (*opt++ != '=') { *log_msgptr = string_sprintf("'=' expected after \"maxwait\" in " "ACL condition \"%s\"", arg); return ERROR; } while (isspace(*opt)) opt++; callout_overall = readconf_readtime(opt, 0, FALSE); if (callout_overall < 0) { *log_msgptr = string_sprintf("bad time value in ACL condition " "\"verify %s\"", arg); return ERROR; } } else if (strncmpic(opt, US"connect", 7) == 0) { opt += 7; while (isspace(*opt)) opt++; if (*opt++ != '=') { *log_msgptr = string_sprintf("'=' expected after " "\"callout_overaall\" in ACL condition \"%s\"", arg); return ERROR; } while (isspace(*opt)) opt++; callout_connect = readconf_readtime(opt, 0, FALSE); if (callout_connect < 0) { *log_msgptr = string_sprintf("bad time value in ACL condition " "\"verify %s\"", arg); return ERROR; } } else /* Plain time is callout connect/command timeout */ { callout = readconf_readtime(opt, 0, FALSE); if (callout < 0) { *log_msgptr = string_sprintf("bad time value in ACL condition " "\"verify %s\"", arg); return ERROR; } } } } else { *log_msgptr = string_sprintf("'=' expected after \"callout\" in " "ACL condition \"%s\"", arg); return ERROR; } } } /* Option not recognized */ else { *log_msgptr = string_sprintf("unknown option \"%s\" in ACL " "condition \"verify %s\"", ss, arg); return ERROR; } } if ((verify_options & (vopt_callout_recipsender|vopt_callout_recippmaster)) == (vopt_callout_recipsender|vopt_callout_recippmaster)) { *log_msgptr = US"only one of use_sender and use_postmaster can be set " "for a recipient callout"; return ERROR; } /* Handle sender-in-header verification. Default the user message to the log message if giving out verification details. */ if (verify_header_sender) { int verrno; rc = verify_check_header_address(user_msgptr, log_msgptr, callout, callout_overall, callout_connect, se_mailfrom, pm_mailfrom, verify_options, &verrno); if (rc != OK) { *basic_errno = verrno; if (smtp_return_error_details) { if (*user_msgptr == NULL && *log_msgptr != NULL) *user_msgptr = string_sprintf("Rejected after DATA: %s", *log_msgptr); if (rc == DEFER) acl_temp_details = TRUE; } } } /* Handle a sender address. The default is to verify *the* sender address, but optionally a different address can be given, for special requirements. If the address is empty, we are dealing with a bounce message that has no sender, so we cannot do any checking. If the real sender address gets rewritten during verification (e.g. DNS widening), set the flag to stop it being rewritten again during message reception. A list of verified "sender" addresses is kept to try to avoid doing to much work repetitively when there are multiple recipients in a message and they all require sender verification. However, when callouts are involved, it gets too complicated because different recipients may require different callout options. Therefore, we always do a full sender verify when any kind of callout is specified. Caching elsewhere, for instance in the DNS resolver and in the callout handling, should ensure that this is not terribly inefficient. */ else if (verify_sender_address != NULL) { if ((verify_options & (vopt_callout_recipsender|vopt_callout_recippmaster)) != 0) { *log_msgptr = US"use_sender or use_postmaster cannot be used for a " "sender verify callout"; return ERROR; } sender_vaddr = verify_checked_sender(verify_sender_address); if (sender_vaddr != NULL && /* Previously checked */ callout <= 0) /* No callout needed this time */ { /* If the "routed" flag is set, it means that routing worked before, so this check can give OK (the saved return code value, if set, belongs to a callout that was done previously). If the "routed" flag is not set, routing must have failed, so we use the saved return code. */ if (testflag(sender_vaddr, af_verify_routed)) rc = OK; else { rc = sender_vaddr->special_action; *basic_errno = sender_vaddr->basic_errno; } HDEBUG(D_acl) debug_printf("using cached sender verify result\n"); } /* Do a new verification, and cache the result. The cache is used to avoid verifying the sender multiple times for multiple RCPTs when callouts are not specified (see comments above). The cache is also used on failure to give details in response to the first RCPT that gets bounced for this reason. However, this can be suppressed by the no_details option, which sets the flag that says "this detail has already been sent". The cache normally contains just one address, but there may be more in esoteric circumstances. */ else { BOOL routed = TRUE; uschar *save_address_data = deliver_address_data; sender_vaddr = deliver_make_addr(verify_sender_address, TRUE); if (no_details) setflag(sender_vaddr, af_sverify_told); if (verify_sender_address[0] != 0) { /* If this is the real sender address, save the unrewritten version for use later in receive. Otherwise, set a flag so that rewriting the sender in verify_address() does not update sender_address. */ if (verify_sender_address == sender_address) sender_address_unrewritten = sender_address; else verify_options |= vopt_fake_sender; if (success_on_redirect) verify_options |= vopt_success_on_redirect; /* The recipient, qualify, and expn options are never set in verify_options. */ rc = verify_address(sender_vaddr, NULL, verify_options, callout, callout_overall, callout_connect, se_mailfrom, pm_mailfrom, &routed); HDEBUG(D_acl) debug_printf("----------- end verify ------------\n"); if (rc == OK) { if (Ustrcmp(sender_vaddr->address, verify_sender_address) != 0) { DEBUG(D_acl) debug_printf("sender %s verified ok as %s\n", verify_sender_address, sender_vaddr->address); } else { DEBUG(D_acl) debug_printf("sender %s verified ok\n", verify_sender_address); } } else *basic_errno = sender_vaddr->basic_errno; } else rc = OK; /* Null sender */ /* Cache the result code */ if (routed) setflag(sender_vaddr, af_verify_routed); if (callout > 0) setflag(sender_vaddr, af_verify_callout); sender_vaddr->special_action = rc; sender_vaddr->next = sender_verified_list; sender_verified_list = sender_vaddr; /* Restore the recipient address data, which might have been clobbered by the sender verification. */ deliver_address_data = save_address_data; } /* Put the sender address_data value into $sender_address_data */ sender_address_data = sender_vaddr->p.address_data; } /* A recipient address just gets a straightforward verify; again we must handle the DEFER overrides. */ else { address_item addr2; if (success_on_redirect) verify_options |= vopt_success_on_redirect; /* We must use a copy of the address for verification, because it might get rewritten. */ addr2 = *addr; rc = verify_address(&addr2, NULL, verify_options|vopt_is_recipient, callout, callout_overall, callout_connect, se_mailfrom, pm_mailfrom, NULL); HDEBUG(D_acl) debug_printf("----------- end verify ------------\n"); *log_msgptr = addr2.message; *user_msgptr = (addr2.user_message != NULL)? addr2.user_message : addr2.message; *basic_errno = addr2.basic_errno; /* Make $address_data visible */ deliver_address_data = addr2.p.address_data; } /* We have a result from the relevant test. Handle defer overrides first. */ if (rc == DEFER && (defer_ok || (callout_defer_ok && *basic_errno == ERRNO_CALLOUTDEFER))) { HDEBUG(D_acl) debug_printf("verify defer overridden by %s\n", defer_ok? "defer_ok" : "callout_defer_ok"); rc = OK; } /* If we've failed a sender, set up a recipient message, and point sender_verified_failed to the address item that actually failed. */ if (rc != OK && verify_sender_address != NULL) { if (rc != DEFER) { *log_msgptr = *user_msgptr = US"Sender verify failed"; } else if (*basic_errno != ERRNO_CALLOUTDEFER) { *log_msgptr = *user_msgptr = US"Could not complete sender verify"; } else { *log_msgptr = US"Could not complete sender verify callout"; *user_msgptr = smtp_return_error_details? sender_vaddr->user_message : *log_msgptr; } sender_verified_failed = sender_vaddr; } /* Verifying an address messes up the values of $domain and $local_part, so reset them before returning if this is a RCPT ACL. */ if (addr != NULL) { deliver_domain = addr->domain; deliver_localpart = addr->local_part; } return rc; /* Syntax errors in the verify argument come here. */ BAD_VERIFY: *log_msgptr = string_sprintf("expected \"sender[=address]\", \"recipient\", " "\"helo\", \"header_syntax\", \"header_sender\" or " "\"reverse_host_lookup\" at start of ACL condition " "\"verify %s\"", arg); return ERROR; /* Options supplied when not allowed come here */ NO_OPTIONS: *log_msgptr = string_sprintf("unexpected '/' found in \"%s\" " "(this verify item has no options)", arg); return ERROR; /* Calls in the wrong ACL come here */ WRONG_ACL: *log_msgptr = string_sprintf("cannot check header contents in ACL for %s " "(only possible in ACL for DATA)", acl_wherenames[where]); return ERROR; } /************************************************* * Check argument for control= modifier * *************************************************/ /* Called from acl_check_condition() below Arguments: arg the argument string for control= pptr set to point to the terminating character where which ACL we are in log_msgptr for error messages Returns: CONTROL_xxx value */ static int decode_control(uschar *arg, uschar **pptr, int where, uschar **log_msgptr) { int len; control_def *d; for (d = controls_list; d < controls_list + sizeof(controls_list)/sizeof(control_def); d++) { len = Ustrlen(d->name); if (Ustrncmp(d->name, arg, len) == 0) break; } if (d >= controls_list + sizeof(controls_list)/sizeof(control_def) || (arg[len] != 0 && (!d->has_option || arg[len] != '/'))) { *log_msgptr = string_sprintf("syntax error in \"control=%s\"", arg); return CONTROL_ERROR; } *pptr = arg + len; return d->value; } /************************************************* * Handle rate limiting * *************************************************/ /* Called by acl_check_condition() below to calculate the result of the ACL ratelimit condition. Note that the return value might be slightly unexpected: if the sender's rate is above the limit then the result is OK. This is similar to the dnslists condition, and is so that you can write ACL clauses like: defer ratelimit = 15 / 1h Arguments: arg the option string for ratelimit= log_msgptr for error messages Returns: OK - Sender's rate is above limit FAIL - Sender's rate is below limit DEFER - Problem opening ratelimit database ERROR - Syntax error in options. */ static int acl_ratelimit(uschar *arg, uschar **log_msgptr) { double limit, period; uschar *ss, *key; int sep = '/'; BOOL have_key = FALSE, leaky = FALSE, strict = FALSE; BOOL per_byte = FALSE, per_cmd = FALSE, per_conn = FALSE, per_mail = FALSE; int old_pool, rc; tree_node **anchor, *t; open_db dbblock, *dbm; dbdata_ratelimit *dbd; struct timeval tv; /* Parse the first two options and record their values in expansion variables. These variables allow the configuration to have informative error messages based on rate limits obtained from a table lookup. */ /* First is the maximum number of messages per period and maximum burst size, which must be greater than or equal to zero. Zero is useful for rate measurement as opposed to rate limiting. */ sender_rate_limit = string_nextinlist(&arg, &sep, NULL, 0); if (sender_rate_limit == NULL) limit = -1.0; else { limit = Ustrtod(sender_rate_limit, &ss); if (tolower(*ss) == 'k') { limit *= 1024.0; ss++; } else if (tolower(*ss) == 'm') { limit *= 1024.0*1024.0; ss++; } else if (tolower(*ss) == 'g') { limit *= 1024.0*1024.0*1024.0; ss++; } } if (limit < 0.0 || *ss != 0) { *log_msgptr = string_sprintf("syntax error in argument for " "\"ratelimit\" condition: \"%s\" is not a positive number", sender_rate_limit); return ERROR; } /* We use the rest of the argument list following the limit as the lookup key, because it doesn't make sense to use the same stored data if the period or options are different. */ key = arg; /* Second is the rate measurement period and exponential smoothing time constant. This must be strictly greater than zero, because zero leads to run-time division errors. */ sender_rate_period = string_nextinlist(&arg, &sep, NULL, 0); if (sender_rate_period == NULL) period = -1.0; else period = readconf_readtime(sender_rate_period, 0, FALSE); if (period <= 0.0) { *log_msgptr = string_sprintf("syntax error in argument for " "\"ratelimit\" condition: \"%s\" is not a time value", sender_rate_period); return ERROR; } /* Parse the other options. Should we check if the per_* options are being used in ACLs where they don't make sense, e.g. per_mail in the connect ACL? */ while ((ss = string_nextinlist(&arg, &sep, big_buffer, big_buffer_size)) != NULL) { if (strcmpic(ss, US"leaky") == 0) leaky = TRUE; else if (strcmpic(ss, US"strict") == 0) strict = TRUE; else if (strcmpic(ss, US"per_byte") == 0) per_byte = TRUE; else if (strcmpic(ss, US"per_cmd") == 0) per_cmd = TRUE; else if (strcmpic(ss, US"per_conn") == 0) per_conn = TRUE; else if (strcmpic(ss, US"per_mail") == 0) per_mail = TRUE; else if (strcmpic(ss, US"per_rcpt") == 0) per_cmd = TRUE; /* alias */ else have_key = TRUE; } if (leaky + strict > 1 || per_byte + per_cmd + per_conn + per_mail > 1) { *log_msgptr = US"conflicting options for \"ratelimit\" condition"; return ERROR; } /* Default option values */ if (!strict) leaky = TRUE; if (!per_byte && !per_cmd && !per_conn) per_mail = TRUE; /* If there is no explicit key, use the sender_host_address. If there is no sender_host_address (e.g. -bs or acl_not_smtp) then we simply omit it. */ if (!have_key && sender_host_address != NULL) key = string_sprintf("%s / %s", key, sender_host_address); HDEBUG(D_acl) debug_printf("ratelimit condition limit=%.0f period=%.0f key=%s\n", limit, period, key); /* See if we have already computed the rate by looking in the relevant tree. For per-connection rate limiting, store tree nodes and dbdata in the permanent pool so that they survive across resets. */ anchor = NULL; old_pool = store_pool; if (per_conn) { anchor = &ratelimiters_conn; store_pool = POOL_PERM; } else if (per_mail || per_byte) anchor = &ratelimiters_mail; else if (per_cmd) anchor = &ratelimiters_cmd; if (anchor != NULL && (t = tree_search(*anchor, key)) != NULL) { dbd = t->data.ptr; /* The following few lines duplicate some of the code below. */ if (dbd->rate < limit) rc = FAIL; else rc = OK; store_pool = old_pool; sender_rate = string_sprintf("%.1f", dbd->rate); HDEBUG(D_acl) debug_printf("ratelimit found pre-computed rate %s\n", sender_rate); return rc; } /* We aren't using a pre-computed rate, so get a previously recorded rate from the database, update it, and write it back. If there's no previous rate for this key, create one. */ dbm = dbfn_open(US"ratelimit", O_RDWR, &dbblock, TRUE); if (dbm == NULL) { store_pool = old_pool; sender_rate = NULL; HDEBUG(D_acl) debug_printf("ratelimit database not available\n"); *log_msgptr = US"ratelimit database not available"; return DEFER; } dbd = dbfn_read(dbm, key); gettimeofday(&tv, NULL); if (dbd == NULL) { HDEBUG(D_acl) debug_printf("ratelimit initializing new key's data\n"); dbd = store_get(sizeof(dbdata_ratelimit)); dbd->time_stamp = tv.tv_sec; dbd->time_usec = tv.tv_usec; dbd->rate = 0.0; } else { /* The smoothed rate is computed using an exponentially weighted moving average adjusted for variable sampling intervals. The standard EWMA for a fixed sampling interval is: f'(t) = (1 - a) * f(t) + a * f'(t - 1) where f() is the measured value and f'() is the smoothed value. Old data decays out of the smoothed value exponentially, such that data n samples old is multiplied by a^n. The exponential decay time constant p is defined such that data p samples old is multiplied by 1/e, which means that a = exp(-1/p). We can maintain the same time constant for a variable sampling interval i by using a = exp(-i/p). The rate we are measuring is messages per period, suitable for directly comparing with the limit. The average rate between now and the previous message is period / interval, which we feed into the EWMA as the sample. It turns out that the number of messages required for the smoothed rate to reach the limit when they are sent in a burst is equal to the limit. This can be seen by analysing the value of the smoothed rate after N messages sent at even intervals. Let k = (1 - a) * p/i rate_1 = (1 - a) * p/i + a * rate_0 = k + a * rate_0 rate_2 = k + a * rate_1 = k + a * k + a^2 * rate_0 rate_3 = k + a * k + a^2 * k + a^3 * rate_0 rate_N = rate_0 * a^N + k * SUM(x=0..N-1)(a^x) = rate_0 * a^N + k * (1 - a^N) / (1 - a) = rate_0 * a^N + p/i * (1 - a^N) When N is large, a^N -> 0 so rate_N -> p/i as desired. rate_N = p/i + (rate_0 - p/i) * a^N a^N = (rate_N - p/i) / (rate_0 - p/i) N * -i/p = log((rate_N - p/i) / (rate_0 - p/i)) N = p/i * log((rate_0 - p/i) / (rate_N - p/i)) Numerical analysis of the above equation, setting the computed rate to increase from rate_0 = 0 to rate_N = limit, shows that for large sending rates, p/i, the number of messages N = limit. So limit serves as both the maximum rate measured in messages per period, and the maximum number of messages that can be sent in a fast burst. */ double this_time = (double)tv.tv_sec + (double)tv.tv_usec / 1000000.0; double prev_time = (double)dbd->time_stamp + (double)dbd->time_usec / 1000000.0; /* We must avoid division by zero, and deal gracefully with the clock going backwards. If we blunder ahead when time is in reverse then the computed rate will be bogus. To be safe we clamp interval to a very small number. */ double interval = this_time - prev_time <= 0.0 ? 1e-9 : this_time - prev_time; double i_over_p = interval / period; double a = exp(-i_over_p); dbd->time_stamp = tv.tv_sec; dbd->time_usec = tv.tv_usec; /* If we are measuring the rate in bytes per period, multiply the measured rate by the message size. If we don't know the message size then it's safe to just use a value of zero and let the recorded rate decay as if nothing happened. */ if (per_byte) dbd->rate = (message_size < 0 ? 0.0 : (double)message_size) * (1 - a) / i_over_p + a * dbd->rate; else dbd->rate = (1 - a) / i_over_p + a * dbd->rate; } /* Clients sending at the limit are considered to be over the limit. This matters for edge cases such the first message sent by a client (which gets the initial rate of 0.0) when the rate limit is zero (i.e. the client should be completely blocked). */ if (dbd->rate < limit) rc = FAIL; else rc = OK; /* Update the state if the rate is low or if we are being strict. If we are in leaky mode and the sender's rate is too high, we do not update the recorded rate in order to avoid an over-aggressive sender's retry rate preventing them from getting any email through. */ if (rc == FAIL || !leaky) dbfn_write(dbm, key, dbd, sizeof(dbdata_ratelimit)); dbfn_close(dbm); /* Store the result in the tree for future reference, if necessary. */ if (anchor != NULL) { t = store_get(sizeof(tree_node) + Ustrlen(key)); t->data.ptr = dbd; Ustrcpy(t->name, key); (void)tree_insertnode(anchor, t); } /* We create the formatted version of the sender's rate very late in order to ensure that it is done using the correct storage pool. */ store_pool = old_pool; sender_rate = string_sprintf("%.1f", dbd->rate); HDEBUG(D_acl) debug_printf("ratelimit computed rate %s\n", sender_rate); return rc; } /************************************************* * Handle conditions/modifiers on an ACL item * *************************************************/ /* Called from acl_check() below. Arguments: verb ACL verb cb ACL condition block - if NULL, result is OK where where called from addr the address being checked for RCPT, or NULL level the nesting level epp pointer to pass back TRUE if "endpass" encountered (applies only to "accept" and "discard") user_msgptr user message pointer log_msgptr log message pointer basic_errno pointer to where to put verify error Returns: OK - all conditions are met DISCARD - an "acl" condition returned DISCARD - only allowed for "accept" or "discard" verbs FAIL - at least one condition fails FAIL_DROP - an "acl" condition returned FAIL_DROP DEFER - can't tell at the moment (typically, lookup defer, but can be temporary callout problem) ERROR - ERROR from nested ACL or expansion failure or other error */ static int acl_check_condition(int verb, acl_condition_block *cb, int where, address_item *addr, int level, BOOL *epp, uschar **user_msgptr, uschar **log_msgptr, int *basic_errno) { uschar *user_message = NULL; uschar *log_message = NULL; uschar *p; int rc = OK; #ifdef WITH_CONTENT_SCAN int sep = '/'; #endif for (; cb != NULL; cb = cb->next) { uschar *arg; int control_type; /* The message and log_message items set up messages to be used in case of rejection. They are expanded later. */ if (cb->type == ACLC_MESSAGE) { user_message = cb->arg; continue; } if (cb->type == ACLC_LOG_MESSAGE) { log_message = cb->arg; continue; } /* The endpass "condition" just sets a flag to show it occurred. This is checked at compile time to be on an "accept" or "discard" item. */ if (cb->type == ACLC_ENDPASS) { *epp = TRUE; continue; } /* For other conditions and modifiers, the argument is expanded now for some of them, but not for all, because expansion happens down in some lower level checking functions in some cases. */ if (cond_expand_at_top[cb->type]) { arg = expand_string(cb->arg); if (arg == NULL) { if (expand_string_forcedfail) continue; *log_msgptr = string_sprintf("failed to expand ACL string \"%s\": %s", cb->arg, expand_string_message); return search_find_defer? DEFER : ERROR; } } else arg = cb->arg; /* Show condition, and expanded condition if it's different */ HDEBUG(D_acl) { int lhswidth = 0; debug_printf("check %s%s %n", (!cond_modifiers[cb->type] && cb->u.negated)? "!":"", conditions[cb->type], &lhswidth); if (cb->type == ACLC_SET) { int n = cb->u.varnumber; int t = (n < ACL_C_MAX)? 'c' : 'm'; if (n >= ACL_C_MAX) n -= ACL_C_MAX; debug_printf("acl_%c%d ", t, n); lhswidth += 7; } debug_printf("= %s\n", cb->arg); if (arg != cb->arg) debug_printf("%.*s= %s\n", lhswidth, US" ", CS arg); } /* Check that this condition makes sense at this time */ if ((cond_forbids[cb->type] & (1 << where)) != 0) { *log_msgptr = string_sprintf("cannot %s %s condition in %s ACL", cond_modifiers[cb->type]? "use" : "test", conditions[cb->type], acl_wherenames[where]); return ERROR; } /* Run the appropriate test for each condition, or take the appropriate action for the remaining modifiers. */ switch(cb->type) { /* A nested ACL that returns "discard" makes sense only for an "accept" or "discard" verb. */ case ACLC_ACL: rc = acl_check_internal(where, addr, arg, level+1, user_msgptr, log_msgptr); if (rc == DISCARD && verb != ACL_ACCEPT && verb != ACL_DISCARD) { *log_msgptr = string_sprintf("nested ACL returned \"discard\" for " "\"%s\" command (only allowed with \"accept\" or \"discard\")", verbs[verb]); return ERROR; } break; case ACLC_AUTHENTICATED: rc = (sender_host_authenticated == NULL)? FAIL : match_isinlist(sender_host_authenticated, &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; #ifdef EXPERIMENTAL_BRIGHTMAIL case ACLC_BMI_OPTIN: { int old_pool = store_pool; store_pool = POOL_PERM; bmi_current_optin = string_copy(arg); store_pool = old_pool; } break; #endif case ACLC_CONDITION: if (Ustrspn(arg, "0123456789") == Ustrlen(arg)) /* Digits, or empty */ rc = (Uatoi(arg) == 0)? FAIL : OK; else rc = (strcmpic(arg, US"no") == 0 || strcmpic(arg, US"false") == 0)? FAIL : (strcmpic(arg, US"yes") == 0 || strcmpic(arg, US"true") == 0)? OK : DEFER; if (rc == DEFER) *log_msgptr = string_sprintf("invalid \"condition\" value \"%s\"", arg); break; case ACLC_CONTROL: control_type = decode_control(arg, &p, where, log_msgptr); /* Check if this control makes sense at this time */ if ((control_forbids[control_type] & (1 << where)) != 0) { *log_msgptr = string_sprintf("cannot use \"control=%s\" in %s ACL", controls[control_type], acl_wherenames[where]); return ERROR; } switch(control_type) { #ifdef EXPERIMENTAL_BRIGHTMAIL case CONTROL_BMI_RUN: bmi_run = 1; break; #endif #ifdef EXPERIMENTAL_DOMAINKEYS case CONTROL_DK_VERIFY: dk_do_verify = 1; break; #endif case CONTROL_ERROR: return ERROR; case CONTROL_CASEFUL_LOCAL_PART: deliver_localpart = addr->cc_local_part; break; case CONTROL_CASELOWER_LOCAL_PART: deliver_localpart = addr->lc_local_part; break; case CONTROL_ENFORCE_SYNC: smtp_enforce_sync = TRUE; break; case CONTROL_NO_ENFORCE_SYNC: smtp_enforce_sync = FALSE; break; #ifdef WITH_CONTENT_SCAN case CONTROL_NO_MBOX_UNSPOOL: no_mbox_unspool = TRUE; break; #endif case CONTROL_NO_MULTILINE: no_multiline_responses = TRUE; break; case CONTROL_FAKEDEFER: case CONTROL_FAKEREJECT: fake_response = (control_type == CONTROL_FAKEDEFER) ? DEFER : FAIL; if (*p == '/') { uschar *pp = p + 1; while (*pp != 0) pp++; fake_response_text = expand_string(string_copyn(p+1, pp-p-1)); p = pp; } else { /* Explicitly reset to default string */ fake_response_text = US"Your message has been rejected but is being kept for evaluation.\nIf it was a legitimate message, it may still be delivered to the target recipient(s)."; } break; case CONTROL_FREEZE: deliver_freeze = TRUE; deliver_frozen_at = time(NULL); break; case CONTROL_QUEUE_ONLY: queue_only_policy = TRUE; break; case CONTROL_SUBMISSION: originator_name = US""; submission_mode = TRUE; while (*p == '/') { if (Ustrncmp(p, "/sender_retain", 14) == 0) { p += 14; active_local_sender_retain = TRUE; active_local_from_check = FALSE; } else if (Ustrncmp(p, "/domain=", 8) == 0) { uschar *pp = p + 8; while (*pp != 0 && *pp != '/') pp++; submission_domain = string_copyn(p+8, pp-p-8); p = pp; } /* The name= option must be last, because it swallows the rest of the string. */ else if (Ustrncmp(p, "/name=", 6) == 0) { uschar *pp = p + 6; while (*pp != 0) pp++; submission_name = string_copy(parse_fix_phrase(p+6, pp-p-6, big_buffer, big_buffer_size)); p = pp; } else break; } if (*p != 0) { *log_msgptr = string_sprintf("syntax error in \"control=%s\"", arg); return ERROR; } break; case CONTROL_SUPPRESS_LOCAL_FIXUPS: suppress_local_fixups = TRUE; break; } break; #ifdef WITH_CONTENT_SCAN case ACLC_DECODE: rc = mime_decode(&arg); break; #endif case ACLC_DELAY: { int delay = readconf_readtime(arg, 0, FALSE); if (delay < 0) { *log_msgptr = string_sprintf("syntax error in argument for \"delay\" " "modifier: \"%s\" is not a time value", arg); return ERROR; } else { HDEBUG(D_acl) debug_printf("delay modifier requests %d-second delay\n", delay); if (host_checking) { HDEBUG(D_acl) debug_printf("delay skipped in -bh checking mode\n"); } /* It appears to be impossible to detect that a TCP/IP connection has gone away without reading from it. This means that we cannot shorten the delay below if the client goes away, because we cannot discover that the client has closed its end of the connection. (The connection is actually in a half-closed state, waiting for the server to close its end.) It would be nice to be able to detect this state, so that the Exim process is not held up unnecessarily. However, it seems that we can't. The poll() function does not do the right thing, and in any case it is not always available. NOTE: If ever this state of affairs changes, remember that we may be dealing with stdin/stdout here, in addition to TCP/IP connections. Whatever is done must work in both cases. To detected the stdin/stdout case, check for smtp_in or smtp_out being NULL. */ else { while (delay > 0) delay = sleep(delay); } } } break; #ifdef WITH_OLD_DEMIME case ACLC_DEMIME: rc = demime(&arg); break; #endif #ifdef EXPERIMENTAL_DOMAINKEYS case ACLC_DK_DOMAIN_SOURCE: if (dk_verify_block == NULL) { rc = FAIL; break; }; /* check header source of domain against given string */ switch (dk_verify_block->address_source) { case DK_EXIM_ADDRESS_FROM_FROM: rc = match_isinlist(US"from", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; case DK_EXIM_ADDRESS_FROM_SENDER: rc = match_isinlist(US"sender", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; case DK_EXIM_ADDRESS_NONE: rc = match_isinlist(US"none", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; } break; case ACLC_DK_POLICY: if (dk_verify_block == NULL) { rc = FAIL; break; }; /* check policy against given string, default FAIL */ rc = FAIL; if (dk_verify_block->signsall) rc = match_isinlist(US"signsall", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); if (dk_verify_block->testing) rc = match_isinlist(US"testing", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; case ACLC_DK_SENDER_DOMAINS: if (dk_verify_block == NULL) { rc = FAIL; break; }; if (dk_verify_block->domain != NULL) rc = match_isinlist(dk_verify_block->domain, &arg, 0, &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL); else rc = FAIL; break; case ACLC_DK_SENDER_LOCAL_PARTS: if (dk_verify_block == NULL) { rc = FAIL; break; }; if (dk_verify_block->local_part != NULL) rc = match_isinlist(dk_verify_block->local_part, &arg, 0, &localpartlist_anchor, NULL, MCL_LOCALPART, TRUE, NULL); else rc = FAIL; break; case ACLC_DK_SENDERS: if (dk_verify_block == NULL) { rc = FAIL; break; }; if (dk_verify_block->address != NULL) rc = match_address_list(dk_verify_block->address, TRUE, TRUE, &arg, NULL, -1, 0, NULL); else rc = FAIL; break; case ACLC_DK_STATUS: if (dk_verify_block == NULL) { rc = FAIL; break; }; if (dk_verify_block->result > 0) { switch(dk_verify_block->result) { case DK_EXIM_RESULT_BAD_FORMAT: rc = match_isinlist(US"bad format", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; case DK_EXIM_RESULT_NO_KEY: rc = match_isinlist(US"no key", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; case DK_EXIM_RESULT_NO_SIGNATURE: rc = match_isinlist(US"no signature", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; case DK_EXIM_RESULT_REVOKED: rc = match_isinlist(US"revoked", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; case DK_EXIM_RESULT_NON_PARTICIPANT: rc = match_isinlist(US"non-participant", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; case DK_EXIM_RESULT_GOOD: rc = match_isinlist(US"good", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; case DK_EXIM_RESULT_BAD: rc = match_isinlist(US"bad", &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); break; } } break; #endif case ACLC_DNSLISTS: rc = verify_check_dnsbl(&arg); break; case ACLC_DOMAINS: rc = match_isinlist(addr->domain, &arg, 0, &domainlist_anchor, addr->domain_cache, MCL_DOMAIN, TRUE, &deliver_domain_data); break; /* The value in tls_cipher is the full cipher name, for example, TLSv1:DES-CBC3-SHA:168, whereas the values to test for are just the cipher names such as DES-CBC3-SHA. But program defensively. We don't know what may in practice come out of the SSL library - which at the time of writing is poorly documented. */ case ACLC_ENCRYPTED: if (tls_cipher == NULL) rc = FAIL; else { uschar *endcipher = NULL; uschar *cipher = Ustrchr(tls_cipher, ':'); if (cipher == NULL) cipher = tls_cipher; else { endcipher = Ustrchr(++cipher, ':'); if (endcipher != NULL) *endcipher = 0; } rc = match_isinlist(cipher, &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL); if (endcipher != NULL) *endcipher = ':'; } break; /* Use verify_check_this_host() instead of verify_check_host() so that we can pass over &host_data to catch any looked up data. Once it has been set, it retains its value so that it's still there if another ACL verb comes through here and uses the cache. However, we must put it into permanent store in case it is also expected to be used in a subsequent message in the same SMTP connection. */ case ACLC_HOSTS: rc = verify_check_this_host(&arg, sender_host_cache, NULL, (sender_host_address == NULL)? US"" : sender_host_address, &host_data); if (host_data != NULL) host_data = string_copy_malloc(host_data); break; case ACLC_LOCAL_PARTS: rc = match_isinlist(addr->cc_local_part, &arg, 0, &localpartlist_anchor, addr->localpart_cache, MCL_LOCALPART, TRUE, &deliver_localpart_data); break; case ACLC_LOGWRITE: { int logbits = 0; uschar *s = arg; if (*s == ':') { s++; while (*s != ':') { if (Ustrncmp(s, "main", 4) == 0) { logbits |= LOG_MAIN; s += 4; } else if (Ustrncmp(s, "panic", 5) == 0) { logbits |= LOG_PANIC; s += 5; } else if (Ustrncmp(s, "reject", 6) == 0) { logbits |= LOG_REJECT; s += 6; } else { logbits = LOG_MAIN|LOG_PANIC; s = string_sprintf(":unknown log name in \"%s\" in " "\"logwrite\" in %s ACL", arg, acl_wherenames[where]); } if (*s == ',') s++; } s++; } while (isspace(*s)) s++; if (logbits == 0) logbits = LOG_MAIN; log_write(0, logbits, "%s", string_printing(s)); } break; #ifdef WITH_CONTENT_SCAN case ACLC_MALWARE: { /* Seperate the regular expression and any optional parameters. */ uschar *ss = string_nextinlist(&arg, &sep, big_buffer, big_buffer_size); /* Run the malware backend. */ rc = malware(&ss); /* Modify return code based upon the existance of options. */ while ((ss = string_nextinlist(&arg, &sep, big_buffer, big_buffer_size)) != NULL) { if (strcmpic(ss, US"defer_ok") == 0 && rc == DEFER) { /* FAIL so that the message is passed to the next ACL */ rc = FAIL; } } } break; case ACLC_MIME_REGEX: rc = mime_regex(&arg); break; #endif case ACLC_RATELIMIT: rc = acl_ratelimit(arg, log_msgptr); break; case ACLC_RECIPIENTS: rc = match_address_list(addr->address, TRUE, TRUE, &arg, NULL, -1, 0, &recipient_data); break; #ifdef WITH_CONTENT_SCAN case ACLC_REGEX: rc = regex(&arg); break; #endif case ACLC_SENDER_DOMAINS: { uschar *sdomain; sdomain = Ustrrchr(sender_address, '@'); sdomain = (sdomain == NULL)? US"" : sdomain + 1; rc = match_isinlist(sdomain, &arg, 0, &domainlist_anchor, sender_domain_cache, MCL_DOMAIN, TRUE, NULL); } break; case ACLC_SENDERS: rc = match_address_list(sender_address, TRUE, TRUE, &arg, sender_address_cache, -1, 0, &sender_data); break; /* Connection variables must persist forever */ case ACLC_SET: { int old_pool = store_pool; if (cb->u.varnumber < ACL_C_MAX) store_pool = POOL_PERM; acl_var[cb->u.varnumber] = string_copy(arg); store_pool = old_pool; } break; #ifdef WITH_CONTENT_SCAN case ACLC_SPAM: { /* Seperate the regular expression and any optional parameters. */ uschar *ss = string_nextinlist(&arg, &sep, big_buffer, big_buffer_size); /* Run the spam backend. */ rc = spam(&ss); /* Modify return code based upon the existance of options. */ while ((ss = string_nextinlist(&arg, &sep, big_buffer, big_buffer_size)) != NULL) { if (strcmpic(ss, US"defer_ok") == 0 && rc == DEFER) { /* FAIL so that the message is passed to the next ACL */ rc = FAIL; } } } break; #endif #ifdef EXPERIMENTAL_SPF case ACLC_SPF: rc = spf_process(&arg, sender_address); break; #endif /* If the verb is WARN, discard any user message from verification, because such messages are SMTP responses, not header additions. The latter come only from explicit "message" modifiers. However, put the user message into $acl_verify_message so it can be used in subsequent conditions or modifiers (until something changes it). */ case ACLC_VERIFY: rc = acl_verify(where, addr, arg, user_msgptr, log_msgptr, basic_errno); acl_verify_message = *user_msgptr; if (verb == ACL_WARN) *user_msgptr = NULL; break; default: log_write(0, LOG_MAIN|LOG_PANIC_DIE, "internal ACL error: unknown " "condition %d", cb->type); break; } /* If a condition was negated, invert OK/FAIL. */ if (!cond_modifiers[cb->type] && cb->u.negated) { if (rc == OK) rc = FAIL; else if (rc == FAIL || rc == FAIL_DROP) rc = OK; } if (rc != OK) break; /* Conditions loop */ } /* If the result is the one for which "message" and/or "log_message" are used, handle the values of these options. Most verbs have but a single return for which the messages are relevant, but for "discard", it's useful to have the log message both when it succeeds and when it fails. Also, for an "accept" that appears in a QUIT ACL, we want to handle the user message. Since only "accept" and "warn" are permitted in that ACL, we don't need to test the verb. These modifiers act in different ways: "message" is a user message that will be included in an SMTP response. Unless it is empty, it overrides any previously set user message. "log_message" is a non-user message, and it adds to any existing non-user message that is already set. If there isn't a log message set, we make it the same as the user message. */ if (((rc == FAIL_DROP)? FAIL : rc) == msgcond[verb] || (verb == ACL_DISCARD && rc == OK) || (where == ACL_WHERE_QUIT)) { uschar *expmessage; /* If the verb is "warn", messages generated by conditions (verification or nested ACLs) are discarded. Only messages specified at this level are used. However, the value of an existing message is available in $acl_verify_message during expansions. */ uschar *old_user_msgptr = *user_msgptr; uschar *old_log_msgptr = (*log_msgptr != NULL)? *log_msgptr : old_user_msgptr; if (verb == ACL_WARN) *log_msgptr = *user_msgptr = NULL; if (user_message != NULL) { acl_verify_message = old_user_msgptr; expmessage = expand_string(user_message); if (expmessage == NULL) { if (!expand_string_forcedfail) log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand ACL message \"%s\": %s", user_message, expand_string_message); } else if (expmessage[0] != 0) *user_msgptr = expmessage; } if (log_message != NULL) { acl_verify_message = old_log_msgptr; expmessage = expand_string(log_message); if (expmessage == NULL) { if (!expand_string_forcedfail) log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand ACL message \"%s\": %s", log_message, expand_string_message); } else if (expmessage[0] != 0) { *log_msgptr = (*log_msgptr == NULL)? expmessage : string_sprintf("%s: %s", expmessage, *log_msgptr); } } /* If no log message, default it to the user message */ if (*log_msgptr == NULL) *log_msgptr = *user_msgptr; } acl_verify_message = NULL; return rc; } /************************************************* * Get line from a literal ACL * *************************************************/ /* This function is passed to acl_read() in order to extract individual lines of a literal ACL, which we access via static pointers. We can destroy the contents because this is called only once (the compiled ACL is remembered). This code is intended to treat the data in the same way as lines in the main Exim configuration file. That is: . Leading spaces are ignored. . A \ at the end of a line is a continuation - trailing spaces after the \ are permitted (this is because I don't believe in making invisible things significant). Leading spaces on the continued part of a line are ignored. . Physical lines starting (significantly) with # are totally ignored, and may appear within a sequence of backslash-continued lines. . Blank lines are ignored, but will end a sequence of continuations. Arguments: none Returns: a pointer to the next line */ static uschar *acl_text; /* Current pointer in the text */ static uschar *acl_text_end; /* Points one past the terminating '0' */ static uschar * acl_getline(void) { uschar *yield; /* This loop handles leading blank lines and comments. */ for(;;) { while (isspace(*acl_text)) acl_text++; /* Leading spaces/empty lines */ if (*acl_text == 0) return NULL; /* No more data */ yield = acl_text; /* Potential data line */ while (*acl_text != 0 && *acl_text != '\n') acl_text++; /* If we hit the end before a newline, we have the whole logical line. If it's a comment, there's no more data to be given. Otherwise, yield it. */ if (*acl_text == 0) return (*yield == '#')? NULL : yield; /* After reaching a newline, end this loop if the physical line does not start with '#'. If it does, it's a comment, and the loop continues. */ if (*yield != '#') break; } /* This loop handles continuations. We know we have some real data, ending in newline. See if there is a continuation marker at the end (ignoring trailing white space). We know that *yield is not white space, so no need to test for cont > yield in the backwards scanning loop. */ for(;;) { uschar *cont; for (cont = acl_text - 1; isspace(*cont); cont--); /* If no continuation follows, we are done. Mark the end of the line and return it. */ if (*cont != '\\') { *acl_text++ = 0; return yield; } /* We have encountered a continuation. Skip over whitespace at the start of the next line, and indeed the whole of the next line or lines if they are comment lines. */ for (;;) { while (*(++acl_text) == ' ' || *acl_text == '\t'); if (*acl_text != '#') break; while (*(++acl_text) != 0 && *acl_text != '\n'); } /* We have the start of a continuation line. Move all the rest of the data to join onto the previous line, and then find its end. If the end is not a newline, we are done. Otherwise loop to look for another continuation. */ memmove(cont, acl_text, acl_text_end - acl_text); acl_text_end -= acl_text - cont; acl_text = cont; while (*acl_text != 0 && *acl_text != '\n') acl_text++; if (*acl_text == 0) return yield; } /* Control does not reach here */ } /************************************************* * Check access using an ACL * *************************************************/ /* This function is called from address_check. It may recurse via acl_check_condition() - hence the use of a level to stop looping. The ACL is passed as a string which is expanded. A forced failure implies no access check is required. If the result is a single word, it is taken as the name of an ACL which is sought in the global ACL tree. Otherwise, it is taken as literal ACL text, complete with newlines, and parsed as such. In both cases, the ACL check is then run. This function uses an auxiliary function for acl_read() to call for reading individual lines of a literal ACL. This is acl_getline(), which appears immediately above. Arguments: where where called from addr address item when called from RCPT; otherwise NULL s the input string; NULL is the same as an empty ACL => DENY level the nesting level 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 DISCARD access is apparently granted... FAIL access is denied FAIL_DROP access is denied; drop the connection DEFER can't tell at the moment ERROR disaster */ static int acl_check_internal(int where, address_item *addr, uschar *s, int level, uschar **user_msgptr, uschar **log_msgptr) { int fd = -1; acl_block *acl = NULL; uschar *acl_name = US"inline ACL"; uschar *ss; /* Catch configuration loops */ if (level > 20) { *log_msgptr = US"ACL nested too deep: possible loop"; return ERROR; } if (s == NULL) { HDEBUG(D_acl) debug_printf("ACL is NULL: implicit DENY\n"); return FAIL; } /* At top level, we expand the incoming string. At lower levels, it has already been expanded as part of condition processing. */ if (level == 0) { ss = expand_string(s); if (ss == NULL) { if (expand_string_forcedfail) return OK; *log_msgptr = string_sprintf("failed to expand ACL string \"%s\": %s", s, expand_string_message); return ERROR; } } else ss = s; while (isspace(*ss))ss++; /* If we can't find a named ACL, the default is to parse it as an inline one. (Unless it begins with a slash; non-existent files give rise to an error.) */ acl_text = ss; /* Handle the case of a string that does not contain any spaces. Look for a named ACL among those read from the configuration, or a previously read file. It is possible that the pointer to the ACL is NULL if the configuration contains a name with no data. If not found, and the text begins with '/', read an ACL from a file, and save it so it can be re-used. */ if (Ustrchr(ss, ' ') == NULL) { tree_node *t = tree_search(acl_anchor, ss); if (t != NULL) { acl = (acl_block *)(t->data.ptr); if (acl == NULL) { HDEBUG(D_acl) debug_printf("ACL \"%s\" is empty: implicit DENY\n", ss); return FAIL; } acl_name = string_sprintf("ACL \"%s\"", ss); HDEBUG(D_acl) debug_printf("using ACL \"%s\"\n", ss); } else if (*ss == '/') { struct stat statbuf; fd = Uopen(ss, O_RDONLY, 0); if (fd < 0) { *log_msgptr = string_sprintf("failed to open ACL file \"%s\": %s", ss, strerror(errno)); return ERROR; } if (fstat(fd, &statbuf) != 0) { *log_msgptr = string_sprintf("failed to fstat ACL file \"%s\": %s", ss, strerror(errno)); return ERROR; } acl_text = store_get(statbuf.st_size + 1); acl_text_end = acl_text + statbuf.st_size + 1; if (read(fd, acl_text, statbuf.st_size) != statbuf.st_size) { *log_msgptr = string_sprintf("failed to read ACL file \"%s\": %s", ss, strerror(errno)); return ERROR; } acl_text[statbuf.st_size] = 0; (void)close(fd); acl_name = string_sprintf("ACL \"%s\"", ss); HDEBUG(D_acl) debug_printf("read ACL from file %s\n", ss); } } /* Parse an ACL that is still in text form. If it came from a file, remember it in the ACL tree, having read it into the POOL_PERM store pool so that it persists between multiple messages. */ if (acl == NULL) { int old_pool = store_pool; if (fd >= 0) store_pool = POOL_PERM; acl = acl_read(acl_getline, log_msgptr); store_pool = old_pool; if (acl == NULL && *log_msgptr != NULL) return ERROR; if (fd >= 0) { tree_node *t = store_get_perm(sizeof(tree_node) + Ustrlen(ss)); Ustrcpy(t->name, ss); t->data.ptr = acl; (void)tree_insertnode(&acl_anchor, t); } } /* Now we have an ACL to use. It's possible it may be NULL. */ while (acl != NULL) { int cond; int basic_errno = 0; BOOL endpass_seen = FALSE; *log_msgptr = *user_msgptr = NULL; acl_temp_details = FALSE; if (where == ACL_WHERE_QUIT && acl->verb != ACL_ACCEPT && acl->verb != ACL_WARN) { *log_msgptr = string_sprintf("\"%s\" is not allowed in a QUIT ACL", verbs[acl->verb]); return ERROR; } HDEBUG(D_acl) debug_printf("processing \"%s\"\n", verbs[acl->verb]); /* Clear out any search error message from a previous check before testing this condition. */ search_error_message = NULL; cond = acl_check_condition(acl->verb, acl->condition, where, addr, level, &endpass_seen, user_msgptr, log_msgptr, &basic_errno); /* Handle special returns: DEFER causes a return except on a WARN verb; ERROR always causes a return. */ switch (cond) { case DEFER: HDEBUG(D_acl) debug_printf("%s: condition test deferred\n", verbs[acl->verb]); if (basic_errno != ERRNO_CALLOUTDEFER) { if (search_error_message != NULL && *search_error_message != 0) *log_msgptr = search_error_message; if (smtp_return_error_details) acl_temp_details = TRUE; } else { acl_temp_details = TRUE; } if (acl->verb != ACL_WARN) return DEFER; break; default: /* Paranoia */ case ERROR: HDEBUG(D_acl) debug_printf("%s: condition test error\n", verbs[acl->verb]); return ERROR; case OK: HDEBUG(D_acl) debug_printf("%s: condition test succeeded\n", verbs[acl->verb]); break; case FAIL: HDEBUG(D_acl) debug_printf("%s: condition test failed\n", verbs[acl->verb]); break; /* DISCARD and DROP can happen only from a nested ACL condition, and DISCARD can happen only for an "accept" or "discard" verb. */ case DISCARD: HDEBUG(D_acl) debug_printf("%s: condition test yielded \"discard\"\n", verbs[acl->verb]); break; case FAIL_DROP: HDEBUG(D_acl) debug_printf("%s: condition test yielded \"drop\"\n", verbs[acl->verb]); break; } /* At this point, cond for most verbs is either OK or FAIL or (as a result of a nested ACL condition) FAIL_DROP. However, for WARN, cond may be DEFER, and for ACCEPT and DISCARD, it may be DISCARD after a nested ACL call. */ switch(acl->verb) { case ACL_ACCEPT: if (cond == OK || cond == DISCARD) return cond; if (endpass_seen) { HDEBUG(D_acl) debug_printf("accept: endpass encountered - denying access\n"); return cond; } break; case ACL_DEFER: if (cond == OK) { acl_temp_details = TRUE; return DEFER; } break; case ACL_DENY: if (cond == OK) return FAIL; break; case ACL_DISCARD: if (cond == OK || cond == DISCARD) return DISCARD; if (endpass_seen) { HDEBUG(D_acl) debug_printf("discard: endpass encountered - denying access\n"); return cond; } break; case ACL_DROP: if (cond == OK) return FAIL_DROP; break; case ACL_REQUIRE: if (cond != OK) return cond; break; case ACL_WARN: if (cond == OK) acl_warn(where, *user_msgptr, *log_msgptr); else if (cond == DEFER && (log_extra_selector & LX_acl_warn_skipped) != 0) log_write(0, LOG_MAIN, "%s Warning: ACL \"warn\" statement skipped: " "condition test deferred%s%s", host_and_ident(TRUE), (*log_msgptr == NULL)? US"" : US": ", (*log_msgptr == NULL)? US"" : *log_msgptr); *log_msgptr = *user_msgptr = NULL; /* In case implicit DENY follows */ break; default: log_write(0, LOG_MAIN|LOG_PANIC_DIE, "internal ACL error: unknown verb %d", acl->verb); break; } /* Pass to the next ACL item */ acl = acl->next; } /* We have reached the end of the ACL. This is an implicit DENY. */ HDEBUG(D_acl) debug_printf("end of %s: implicit DENY\n", acl_name); return FAIL; } /************************************************* * Check access using an ACL * *************************************************/ /* This is the external interface for ACL checks. It sets up an address and the expansions for $domain and $local_part when called after RCPT, then calls acl_check_internal() to do the actual work. Arguments: where ACL_WHERE_xxxx indicating where called from recipient RCPT address for RCPT check, else NULL s the input string; NULL is the same as an empty ACL => DENY 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 acl_check(int where, uschar *recipient, uschar *s, uschar **user_msgptr, uschar **log_msgptr) { int rc; address_item adb; address_item *addr = NULL; *user_msgptr = *log_msgptr = NULL; sender_verified_failed = NULL; ratelimiters_cmd = NULL; if (where == ACL_WHERE_RCPT) { adb = address_defaults; addr = &adb; addr->address = recipient; if (deliver_split_address(addr) == DEFER) { *log_msgptr = US"defer in percent_hack_domains check"; return DEFER; } deliver_domain = addr->domain; deliver_localpart = addr->local_part; } rc = acl_check_internal(where, addr, s, 0, user_msgptr, log_msgptr); deliver_domain = deliver_localpart = deliver_address_data = sender_address_data = NULL; /* A DISCARD response is permitted only for message ACLs, excluding the PREDATA ACL, which is really in the middle of an SMTP command. */ if (rc == DISCARD) { if (where > ACL_WHERE_NOTSMTP || where == ACL_WHERE_PREDATA) { log_write(0, LOG_MAIN|LOG_PANIC, "\"discard\" verb not allowed in %s " "ACL", acl_wherenames[where]); return ERROR; } return DISCARD; } /* A DROP response is not permitted from MAILAUTH */ if (rc == FAIL_DROP && where == ACL_WHERE_MAILAUTH) { log_write(0, LOG_MAIN|LOG_PANIC, "\"drop\" verb not allowed in %s " "ACL", acl_wherenames[where]); return ERROR; } /* Before giving an error response, take a look at the length of any user message, and split it up into multiple lines if possible. */ if (rc != OK && *user_msgptr != NULL && Ustrlen(*user_msgptr) > 75) { uschar *s = *user_msgptr = string_copy(*user_msgptr); uschar *ss = s; for (;;) { int i = 0; while (i < 75 && *ss != 0 && *ss != '\n') ss++, i++; if (*ss == 0) break; if (*ss == '\n') s = ++ss; else { uschar *t = ss + 1; uschar *tt = NULL; while (--t > s + 35) { if (*t == ' ') { if (t[-1] == ':') { tt = t; break; } if (tt == NULL) tt = t; } } if (tt == NULL) /* Can't split behind - try ahead */ { t = ss + 1; while (*t != 0) { if (*t == ' ' || *t == '\n') { tt = t; break; } t++; } } if (tt == NULL) break; /* Can't find anywhere to split */ *tt = '\n'; s = ss = tt+1; } } } return rc; } /* End of acl.c */