/************************************************* * Exim - an Internet mail transport agent * *************************************************/ /* Copyright (c) University of Cambridge 1995 - 2012 */ /* 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 conditions for which "message" or "log_message" are used are held as a bitmap. This is to avoid expanding the strings unnecessarily. For "accept", the FAIL case is used only after "endpass", but that is selected in the code. */ static int msgcond[] = { (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 name to insert into the data block. The original ACL variable names were acl_c0 ... acl_c9 and acl_m0 ... acl_m9. This was extended to 20 of each type, but after that people successfully argued for arbitrary names. In the new scheme, the names must start with acl_c or acl_m. After that, we allow alphanumerics and underscores, but the first character after c or m must be a digit or an underscore. This retains backwards compatibility. */ if (c == ACLC_SET) { uschar *endptr; if (Ustrncmp(s, "acl_c", 5) != 0 && Ustrncmp(s, "acl_m", 5) != 0) { *error = string_sprintf("invalid variable name after \"set\" in ACL " "modifier \"set %s\" (must start \"acl_c\" or \"acl_m\")", s); return NULL; } endptr = s + 5; if (!isdigit(*endptr) && *endptr != '_') { *error = string_sprintf("invalid variable name after \"set\" in ACL " "modifier \"set %s\" (digit or underscore must follow acl_c or acl_m)", s); return NULL; } while (*endptr != 0 && *endptr != '=' && !isspace(*endptr)) { if (!isalnum(*endptr) && *endptr != '_') { *error = string_sprintf("invalid character \"%c\" in variable name " "in ACL modifier \"set %s\"", *endptr, s); return NULL; } endptr++; } cond->u.varname = string_copyn(s + 4, endptr - s - 4); s = endptr; 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; } /************************************************* * Set up added header line(s) * *************************************************/ /* This function is called by the add_header modifier, and also from acl_warn() to implement the now-deprecated way of adding header lines using "message" on a "warn" verb. The argument is treated as a sequence of header lines which are added to a chain, provided there isn't an identical one already there. Argument: string of header lines Returns: nothing */ static void setup_header(uschar *hstring) { uschar *p, *q; int hlen = Ustrlen(hstring); /* An empty string does nothing; otherwise add a final newline if necessary. */ if (hlen <= 0) return; if (hstring[hlen-1] != '\n') hstring = string_sprintf("%s\n", hstring); /* Loop for multiple header lines, taking care about continuations */ for (p = q = hstring; *p != 0; ) { uschar *s; int newtype = htype_add_bot; header_line **hptr = &acl_added_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: ", (int) (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; } } /************************************************* * Set up removed header line(s) * *************************************************/ /* This function is called by the remove_header modifier. The argument is treated as a sequence of header names which are added to a colon separated list, provided there isn't an identical one already there. Argument: string of header names Returns: nothing */ static void setup_remove_header(uschar *hnames) { if (*hnames != 0) { if (acl_removed_headers == NULL) acl_removed_headers = hnames; else acl_removed_headers = string_sprintf("%s : %s", acl_removed_headers, hnames); } } /************************************************* * 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). ** NOTE: The header adding action using the "message" setting is historic, and its use is now deprecated. The new add_header modifier should be used instead. 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) { 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; } /* The code for setting up header lines is now abstracted into a separate function so that it can be used for the add_header modifier as well. */ setup_header(user_message); } /************************************************* * 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) != 0) { 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) * *************************************************/ enum { VERIFY_REV_HOST_LKUP, VERIFY_CERT, VERIFY_HELO, VERIFY_CSA, VERIFY_HDR_SYNTAX, VERIFY_NOT_BLIND, VERIFY_HDR_SNDR, VERIFY_SNDR, VERIFY_RCPT }; typedef struct { uschar * name; int value; unsigned where_allowed; /* bitmap */ BOOL no_options; /* Never has /option(s) following */ unsigned alt_opt_sep; /* >0 Non-/ option separator (custom parser) */ } verify_type_t; static verify_type_t verify_type_list[] = { { US"reverse_host_lookup", VERIFY_REV_HOST_LKUP, ~0, TRUE, 0 }, { US"certificate", VERIFY_CERT, ~0, TRUE, 0 }, { US"helo", VERIFY_HELO, ~0, TRUE, 0 }, { US"csa", VERIFY_CSA, ~0, FALSE, 0 }, { US"header_syntax", VERIFY_HDR_SYNTAX, (1<alt_opt_sep ? strncmpic(ss, vp->name, vp->alt_opt_sep) == 0 : strcmpic (ss, vp->name) == 0) break; if ((char *)vp >= (char *)verify_type_list + sizeof(verify_type_list)) goto BAD_VERIFY; if (vp->no_options && slash != NULL) { *log_msgptr = string_sprintf("unexpected '/' found in \"%s\" " "(this verify item has no options)", arg); return ERROR; } if (!(vp->where_allowed & (1<name, acl_wherenames[where]); return ERROR; } switch(vp->value) { case VERIFY_REV_HOST_LKUP: if (sender_host_address == NULL) return OK; return acl_verify_reverse(user_msgptr, log_msgptr); case VERIFY_CERT: /* 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 (tls_in.certificate_verified) return OK; *user_msgptr = US"no verified certificate"; return FAIL; case VERIFY_HELO: /* We can test the result of optional HELO verification that might have occurred earlier. If not, we can attempt the verification now. */ if (!helo_verified && !helo_verify_failed) smtp_verify_helo(); return helo_verified? OK : FAIL; case VERIFY_CSA: /* Do Client SMTP Authorization checks in a separate function, and turn the result code into user-friendly strings. */ 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]; case VERIFY_HDR_SYNTAX: /* 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). */ 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; case VERIFY_NOT_BLIND: /* Check that no recipient of this message is "blind", that is, every envelope recipient must be mentioned in either To: or Cc:. */ 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. */ case VERIFY_HDR_SNDR: verify_header_sender = TRUE; break; case VERIFY_SNDR: /* 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). */ { uschar *s = ss + 6; 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); } } break; case VERIFY_RCPT: break; } /* 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++; while ((opt = string_nextinlist(&ss, &optsep, buffer, sizeof(buffer))) != NULL) { callout_opt_t * op; double period = 1.0F; for (op= callout_opt_list; op->name; op++) if (strncmpic(opt, op->name, Ustrlen(op->name)) == 0) break; verify_options |= op->flag; if (op->has_option) { opt += Ustrlen(op->name); while (isspace(*opt)) opt++; if (*opt++ != '=') { *log_msgptr = string_sprintf("'=' expected after " "\"%s\" in ACL verify condition \"%s\"", op->name, arg); return ERROR; } while (isspace(*opt)) opt++; } if (op->timeval) { period = readconf_readtime(opt, 0, FALSE); if (period < 0) { *log_msgptr = string_sprintf("bad time value in ACL condition " "\"verify %s\"", arg); return ERROR; } } switch(op->value) { case CALLOUT_DEFER_OK: callout_defer_ok = TRUE; break; case CALLOUT_POSTMASTER: pm_mailfrom = US""; break; case CALLOUT_FULLPOSTMASTER: pm_mailfrom = US""; break; case CALLOUT_MAILFROM: 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; } se_mailfrom = string_copy(opt); break; case CALLOUT_POSTMASTER_MAILFROM: pm_mailfrom = string_copy(opt); break; case CALLOUT_MAXWAIT: callout_overall = period; break; case CALLOUT_CONNECT: callout_connect = period; break; case CALLOUT_TIME: callout = period; break; } } } 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"); *basic_errno = addr2.basic_errno; *log_msgptr = addr2.message; *user_msgptr = (addr2.user_message != NULL)? addr2.user_message : addr2.message; /* Allow details for temporary error if the address is so flagged. */ if (testflag((&addr2), af_pass_message)) acl_temp_details = TRUE; /* 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; } /************************************************* * 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; } /************************************************* * Return a ratelimit error * *************************************************/ /* Called from acl_ratelimit() below Arguments: log_msgptr for error messages format format string ... supplementary arguments ss ratelimit option name where ACL_WHERE_xxxx indicating which ACL this is Returns: ERROR */ static int ratelimit_error(uschar **log_msgptr, const char *format, ...) { va_list ap; uschar buffer[STRING_SPRINTF_BUFFER_SIZE]; va_start(ap, format); if (!string_vformat(buffer, sizeof(buffer), format, ap)) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "string_sprintf expansion was longer than " SIZE_T_FMT, sizeof(buffer)); va_end(ap); *log_msgptr = string_sprintf( "error in arguments to \"ratelimit\" condition: %s", buffer); return ERROR; } /************************************************* * 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= where ACL_WHERE_xxxx indicating which ACL this is 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, int where, uschar **log_msgptr) { double limit, period, count; uschar *ss; uschar *key = NULL; uschar *unique = NULL; int sep = '/'; BOOL leaky = FALSE, strict = FALSE, readonly = FALSE; BOOL noupdate = FALSE, badacl = FALSE; int mode = RATE_PER_WHAT; int old_pool, rc; tree_node **anchor, *t; open_db dbblock, *dbm; int dbdb_size; dbdata_ratelimit *dbd; dbdata_ratelimit_unique *dbdb; 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 / 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') return ratelimit_error(log_msgptr, "\"%s\" is not a positive number", sender_rate_limit); /* Second is the rate measurement period / 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) return ratelimit_error(log_msgptr, "\"%s\" is not a time value", sender_rate_period); /* By default we are counting one of something, but the per_rcpt, per_byte, and count options can change this. */ count = 1.0; /* Parse the other options. */ 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"noupdate") == 0) noupdate = TRUE; else if (strcmpic(ss, US"readonly") == 0) readonly = TRUE; else if (strcmpic(ss, US"per_cmd") == 0) RATE_SET(mode, PER_CMD); else if (strcmpic(ss, US"per_conn") == 0) { RATE_SET(mode, PER_CONN); if (where == ACL_WHERE_NOTSMTP || where == ACL_WHERE_NOTSMTP_START) badacl = TRUE; } else if (strcmpic(ss, US"per_mail") == 0) { RATE_SET(mode, PER_MAIL); if (where > ACL_WHERE_NOTSMTP) badacl = TRUE; } else if (strcmpic(ss, US"per_rcpt") == 0) { /* If we are running in the RCPT ACL, then we'll count the recipients one by one, but if we are running when we have accumulated the whole list then we'll add them all in one batch. */ if (where == ACL_WHERE_RCPT) RATE_SET(mode, PER_RCPT); else if (where >= ACL_WHERE_PREDATA && where <= ACL_WHERE_NOTSMTP) RATE_SET(mode, PER_ALLRCPTS), count = (double)recipients_count; else if (where == ACL_WHERE_MAIL || where > ACL_WHERE_NOTSMTP) RATE_SET(mode, PER_RCPT), badacl = TRUE; } else if (strcmpic(ss, US"per_byte") == 0) { /* If we have not yet received the message data and there was no SIZE declaration on the MAIL comand, then it's safe to just use a value of zero and let the recorded rate decay as if nothing happened. */ RATE_SET(mode, PER_MAIL); if (where > ACL_WHERE_NOTSMTP) badacl = TRUE; else count = message_size < 0 ? 0.0 : (double)message_size; } else if (strcmpic(ss, US"per_addr") == 0) { RATE_SET(mode, PER_RCPT); if (where != ACL_WHERE_RCPT) badacl = TRUE, unique = US"*"; else unique = string_sprintf("%s@%s", deliver_localpart, deliver_domain); } else if (strncmpic(ss, US"count=", 6) == 0) { uschar *e; count = Ustrtod(ss+6, &e); if (count < 0.0 || *e != '\0') return ratelimit_error(log_msgptr, "\"%s\" is not a positive number", ss); } else if (strncmpic(ss, US"unique=", 7) == 0) unique = string_copy(ss + 7); else if (key == NULL) key = string_copy(ss); else key = string_sprintf("%s/%s", key, ss); } /* Sanity check. When the badacl flag is set the update mode must either be readonly (which is the default if it is omitted) or, for backwards compatibility, a combination of noupdate and strict or leaky. */ if (mode == RATE_PER_CLASH) return ratelimit_error(log_msgptr, "conflicting per_* options"); if (leaky + strict + readonly > 1) return ratelimit_error(log_msgptr, "conflicting update modes"); if (badacl && (leaky || strict) && !noupdate) return ratelimit_error(log_msgptr, "\"%s\" must not have /leaky or /strict option in %s ACL", ratelimit_option_string[mode], acl_wherenames[where]); /* Set the default values of any unset options. In readonly mode we perform the rate computation without any increment so that its value decays to eventually allow over-limit senders through. */ if (noupdate) readonly = TRUE, leaky = strict = FALSE; if (badacl) readonly = TRUE; if (readonly) count = 0.0; if (!strict && !readonly) leaky = TRUE; if (mode == RATE_PER_WHAT) mode = RATE_PER_MAIL; /* Create the lookup key. If there is no explicit key, use sender_host_address. If there is no sender_host_address (e.g. -bs or acl_not_smtp) then we simply omit it. The smoothing constant (sender_rate_period) and the per_xxx options are added to the key because they alter the meaning of the stored data. */ if (key == NULL) key = (sender_host_address == NULL)? US"" : sender_host_address; key = string_sprintf("%s/%s/%s%s", sender_rate_period, ratelimit_option_string[mode], unique == NULL ? "" : "unique/", key); HDEBUG(D_acl) debug_printf("ratelimit condition count=%.0f %.1f/%s\n", count, limit, 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. In readonly mode we only remember the result for the rest of this command in case a later command changes it. After this bit of logic the code is independent of the per_* mode. */ old_pool = store_pool; if (readonly) anchor = &ratelimiters_cmd; else switch(mode) { case RATE_PER_CONN: anchor = &ratelimiters_conn; store_pool = POOL_PERM; break; case RATE_PER_BYTE: case RATE_PER_MAIL: case RATE_PER_ALLRCPTS: anchor = &ratelimiters_mail; break; case RATE_PER_ADDR: case RATE_PER_CMD: case RATE_PER_RCPT: anchor = &ratelimiters_cmd; break; default: anchor = NULL; /* silence an "unused" complaint */ log_write(0, LOG_MAIN|LOG_PANIC_DIE, "internal ACL error: unknown ratelimit mode %d", mode); break; } t = tree_search(*anchor, key); if (t != NULL) { dbd = t->data.ptr; /* The following few lines duplicate some of the code below. */ rc = (dbd->rate < limit)? FAIL : 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, which will be updated and written back if required. */ 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; } dbdb = dbfn_read_with_length(dbm, key, &dbdb_size); dbd = NULL; gettimeofday(&tv, NULL); if (dbdb != NULL) { /* Locate the basic ratelimit block inside the DB data. */ HDEBUG(D_acl) debug_printf("ratelimit found key in database\n"); dbd = &dbdb->dbd; /* Forget the old Bloom filter if it is too old, so that we count each repeating event once per period. We don't simply clear and re-use the old filter because we want its size to change if the limit changes. Note that we keep the dbd pointer for copying the rate into the new data block. */ if(unique != NULL && tv.tv_sec > dbdb->bloom_epoch + period) { HDEBUG(D_acl) debug_printf("ratelimit discarding old Bloom filter\n"); dbdb = NULL; } /* Sanity check. */ if(unique != NULL && dbdb_size < sizeof(*dbdb)) { HDEBUG(D_acl) debug_printf("ratelimit discarding undersize Bloom filter\n"); dbdb = NULL; } } /* Allocate a new data block if the database lookup failed or the Bloom filter passed its age limit. */ if (dbdb == NULL) { if (unique == NULL) { /* No Bloom filter. This basic ratelimit block is initialized below. */ HDEBUG(D_acl) debug_printf("ratelimit creating new rate data block\n"); dbdb_size = sizeof(*dbd); dbdb = store_get(dbdb_size); } else { int extra; HDEBUG(D_acl) debug_printf("ratelimit creating new Bloom filter\n"); /* See the long comment below for an explanation of the magic number 2. The filter has a minimum size in case the rate limit is very small; this is determined by the definition of dbdata_ratelimit_unique. */ extra = (int)limit * 2 - sizeof(dbdb->bloom); if (extra < 0) extra = 0; dbdb_size = sizeof(*dbdb) + extra; dbdb = store_get(dbdb_size); dbdb->bloom_epoch = tv.tv_sec; dbdb->bloom_size = sizeof(dbdb->bloom) + extra; memset(dbdb->bloom, 0, dbdb->bloom_size); /* Preserve any basic ratelimit data (which is our longer-term memory) by copying it from the discarded block. */ if (dbd != NULL) { dbdb->dbd = *dbd; dbd = &dbdb->dbd; } } } /* If we are counting unique events, find out if this event is new or not. If the client repeats the event during the current period then it should be counted. We skip this code in readonly mode for efficiency, because any changes to the filter will be discarded and because count is already set to zero. */ if (unique != NULL && !readonly) { /* We identify unique events using a Bloom filter. (You can find my notes on Bloom filters at http://fanf.livejournal.com/81696.html) With the per_addr option, an "event" is a recipient address, though the user can use the unique option to define their own events. We only count an event if we have not seen it before. We size the filter according to the rate limit, which (in leaky mode) is the limit on the population of the filter. We allow 16 bits of space per entry (see the construction code above) and we set (up to) 8 of them when inserting an element (see the loop below). The probability of a false positive (an event we have not seen before but which we fail to count) is size = limit * 16 numhash = 8 allzero = exp(-numhash * pop / size) = exp(-0.5 * pop / limit) fpr = pow(1 - allzero, numhash) For senders at the limit the fpr is 0.06% or 1 in 1700 and for senders at half the limit it is 0.0006% or 1 in 170000 In strict mode the Bloom filter can fill up beyond the normal limit, in which case the false positive rate will rise. This means that the measured rate for very fast senders can bogusly drop off after a while. At twice the limit, the fpr is 2.5% or 1 in 40 At four times the limit, it is 31% or 1 in 3.2 It takes ln(pop/limit) periods for an over-limit burst of pop events to decay below the limit, and if this is more than one then the Bloom filter will be discarded before the decay gets that far. The false positive rate at this threshold is 9.3% or 1 in 10.7. */ BOOL seen; unsigned n, hash, hinc; uschar md5sum[16]; md5 md5info; /* Instead of using eight independent hash values, we combine two values using the formula h1 + n * h2. This does not harm the Bloom filter's performance, and means the amount of hash we need is independent of the number of bits we set in the filter. */ md5_start(&md5info); md5_end(&md5info, unique, Ustrlen(unique), md5sum); hash = md5sum[0] | md5sum[1] << 8 | md5sum[2] << 16 | md5sum[3] << 24; hinc = md5sum[4] | md5sum[5] << 8 | md5sum[6] << 16 | md5sum[7] << 24; /* Scan the bits corresponding to this event. A zero bit means we have not seen it before. Ensure all bits are set to record this event. */ HDEBUG(D_acl) debug_printf("ratelimit checking uniqueness of %s\n", unique); seen = TRUE; for (n = 0; n < 8; n++, hash += hinc) { int bit = 1 << (hash % 8); int byte = (hash / 8) % dbdb->bloom_size; if ((dbdb->bloom[byte] & bit) == 0) { dbdb->bloom[byte] |= bit; seen = FALSE; } } /* If this event has occurred before, do not count it. */ if (seen) { HDEBUG(D_acl) debug_printf("ratelimit event found in Bloom filter\n"); count = 0.0; } else HDEBUG(D_acl) debug_printf("ratelimit event added to Bloom filter\n"); } /* If there was no previous ratelimit data block for this key, initialize the new one, otherwise update the block from the database. The initial rate is what would be computed by the code below for an infinite interval. */ if (dbd == NULL) { HDEBUG(D_acl) debug_printf("ratelimit initializing new key's rate data\n"); dbd = &dbdb->dbd; dbd->time_stamp = tv.tv_sec; dbd->time_usec = tv.tv_usec; dbd->rate = count; } 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); /* Combine the instantaneous rate (period / interval) with the previous rate using the smoothing factor a. In order to measure sized events, multiply the instantaneous rate by the count of bytes or recipients etc. */ dbd->time_stamp = tv.tv_sec; dbd->time_usec = tv.tv_usec; dbd->rate = (1 - a) * count / i_over_p + a * dbd->rate; /* When events are very widely spaced the computed rate tends towards zero. Although this is accurate it turns out not to be useful for our purposes, especially when the first event after a long silence is the start of a spam run. A more useful model is that the rate for an isolated event should be the size of the event per the period size, ignoring the lack of events outside the current period and regardless of where the event falls in the period. So, if the interval was so long that the calculated rate is unhelpfully small, we re-intialize the rate. In the absence of higher-rate bursts, the condition below is true if the interval is greater than the period. */ if (dbd->rate < count) dbd->rate = count; } /* Clients sending at the limit are considered to be over the limit. This matters for edge cases such as a limit of zero, when the client should be completely blocked. */ rc = (dbd->rate < limit)? FAIL : 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 readonly is set, neither leaky nor strict are set, so we do not do any updates. */ if ((rc == FAIL && leaky) || strict) { dbfn_write(dbm, key, dbdb, dbdb_size); HDEBUG(D_acl) debug_printf("ratelimit db updated\n"); } else { HDEBUG(D_acl) debug_printf("ratelimit db not updated: %s\n", readonly? "readonly mode" : "over the limit, but leaky"); } dbfn_close(dbm); /* Store the result in the tree for future reference. */ 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 *debug_tag = NULL; uschar *debug_opts = NULL; uschar *p = NULL; 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) { debug_printf("acl_%s ", cb->u.varname); lhswidth += 5 + Ustrlen(cb->u.varname); } 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) { case ACLC_ADD_HEADER: setup_header(arg); break; /* A nested ACL that returns "discard" makes sense only for an "accept" or "discard" verb. */ case ACLC_ACL: rc = acl_check_wargs(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: /* The true/false parsing here should be kept in sync with that used in expand.c when dealing with ECOND_BOOL so that we don't have too many different definitions of what can be a boolean. */ 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_CONTINUE: /* Always succeeds */ 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) { case CONTROL_AUTH_UNADVERTISED: allow_auth_unadvertised = TRUE; break; #ifdef EXPERIMENTAL_BRIGHTMAIL case CONTROL_BMI_RUN: bmi_run = 1; break; #endif #ifndef DISABLE_DKIM case CONTROL_DKIM_VERIFY: dkim_disable_verify = TRUE; break; #endif case CONTROL_DSCP: if (*p == '/') { int fd, af, level, optname, value; /* If we are acting on stdin, the setsockopt may fail if stdin is not a socket; we can accept that, we'll just debug-log failures anyway. */ fd = fileno(smtp_in); af = ip_get_address_family(fd); if (af < 0) { HDEBUG(D_acl) debug_printf("smtp input is probably not a socket [%s], not setting DSCP\n", strerror(errno)); break; } if (dscp_lookup(p+1, af, &level, &optname, &value)) { if (setsockopt(fd, level, optname, &value, sizeof(value)) < 0) { HDEBUG(D_acl) debug_printf("failed to set input DSCP[%s]: %s\n", p+1, strerror(errno)); } else { HDEBUG(D_acl) debug_printf("set input DSCP to \"%s\"\n", p+1); } } else { *log_msgptr = string_sprintf("unrecognised DSCP value in \"control=%s\"", arg); return ERROR; } } else { *log_msgptr = string_sprintf("syntax error in \"control=%s\"", arg); return ERROR; } break; 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_NO_PIPELINING: pipelining_enable = FALSE; break; case CONTROL_NO_DELAY_FLUSH: disable_delay_flush = TRUE; break; case CONTROL_NO_CALLOUT_FLUSH: disable_callout_flush = 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); freeze_tell = freeze_tell_config; /* Reset to configured value */ if (Ustrncmp(p, "/no_tell", 8) == 0) { p += 8; freeze_tell = NULL; } if (*p != 0) { *log_msgptr = string_sprintf("syntax error in \"control=%s\"", arg); return ERROR; } 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_DEBUG: while (*p == '/') { if (Ustrncmp(p, "/tag=", 5) == 0) { uschar *pp = p + 5; while (*pp != '\0' && *pp != '/') pp++; debug_tag = string_copyn(p+5, pp-p-5); p = pp; } else if (Ustrncmp(p, "/opts=", 6) == 0) { uschar *pp = p + 6; while (*pp != '\0' && *pp != '/') pp++; debug_opts = string_copyn(p+6, pp-p-6); p = pp; } } debug_logging_activate(debug_tag, debug_opts); break; case CONTROL_SUPPRESS_LOCAL_FIXUPS: suppress_local_fixups = TRUE; break; case CONTROL_CUTTHROUGH_DELIVERY: if (deliver_freeze) { *log_msgptr = string_sprintf("\"control=%s\" on frozen item", arg); return ERROR; } if (queue_only_policy) { *log_msgptr = string_sprintf("\"control=%s\" on queue-only item", arg); return ERROR; } cutthrough_delivery = TRUE; break; } break; #ifdef EXPERIMENTAL_DCC case ACLC_DCC: { /* Seperate the regular expression and any optional parameters. */ uschar *ss = string_nextinlist(&arg, &sep, big_buffer, big_buffer_size); /* Run the dcc backend. */ rc = dcc_process(&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 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 1: If ever this state of affairs changes, remember that we may be dealing with stdin/stdout here, in addition to TCP/IP connections. Also, delays may be specified for non-SMTP input, where smtp_out and smtp_in will be NULL. Whatever is done must work in all cases. NOTE 2: The added feature of flushing the output before a delay must apply only to SMTP input. Hence the test for smtp_out being non-NULL. */ else { if (smtp_out != NULL && !disable_delay_flush) mac_smtp_fflush(); while (delay > 0) delay = sleep(delay); } } } break; #ifdef WITH_OLD_DEMIME case ACLC_DEMIME: rc = demime(&arg); break; #endif #ifndef DISABLE_DKIM case ACLC_DKIM_SIGNER: if (dkim_cur_signer != NULL) rc = match_isinlist(dkim_cur_signer, &arg,0,NULL,NULL,MCL_STRING,TRUE,NULL); else rc = FAIL; break; case ACLC_DKIM_STATUS: rc = match_isinlist(dkim_exim_expand_query(DKIM_VERIFY_STATUS), &arg,0,NULL,NULL,MCL_STRING,TRUE,NULL); 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_in.cipher == NULL) rc = FAIL; else { uschar *endcipher = NULL; uschar *cipher = Ustrchr(tls_in.cipher, ':'); if (cipher == NULL) cipher = tls_in.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_LOG_REJECT_TARGET: { int logbits = 0; int sep = 0; uschar *s = arg; uschar *ss; while ((ss = string_nextinlist(&s, &sep, big_buffer, big_buffer_size)) != NULL) { if (Ustrcmp(ss, "main") == 0) logbits |= LOG_MAIN; else if (Ustrcmp(ss, "panic") == 0) logbits |= LOG_PANIC; else if (Ustrcmp(ss, "reject") == 0) logbits |= LOG_REJECT; else { logbits |= LOG_MAIN|LOG_REJECT; log_write(0, LOG_MAIN|LOG_PANIC, "unknown log name \"%s\" in " "\"log_reject_target\" in %s ACL", ss, acl_wherenames[where]); } } log_reject_target = logbits; } 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: { /* Separate 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, where, 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_REMOVE_HEADER: setup_remove_header(arg); break; 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.varname[0] == 'c') store_pool = POOL_PERM; acl_var_create(cb->u.varname)->data.ptr = 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, SPF_PROCESS_NORMAL); break; case ACLC_SPF_GUESS: rc = spf_process(&arg, sender_address, SPF_PROCESS_GUESS); 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 modifiers. If there isn't a log message set, we make it the same as the user message. "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. 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. For "accept", the message is used in the OK case if there is no "endpass", but (for backwards compatibility) in the FAIL case if "endpass" is present. */ if (*epp && rc == OK) user_message = NULL; if (((1< 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 || where == ACL_WHERE_NOTQUIT) && acl->verb != ACL_ACCEPT && acl->verb != ACL_WARN) { *log_msgptr = string_sprintf("\"%s\" is not allowed in a QUIT or not-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 in %s\n", verbs[acl->verb], acl_name); 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 in %s\n", verbs[acl->verb], acl_name); return ERROR; case OK: HDEBUG(D_acl) debug_printf("%s: condition test succeeded in %s\n", verbs[acl->verb], acl_name); break; case FAIL: HDEBUG(D_acl) debug_printf("%s: condition test failed in %s\n", verbs[acl->verb], acl_name); 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\" in %s\n", verbs[acl->verb], acl_name); break; case FAIL_DROP: HDEBUG(D_acl) debug_printf("%s: condition test yielded \"drop\" in %s\n", verbs[acl->verb], acl_name); 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; } /* Same args as acl_check_internal() above, but the string s is the name of an ACL followed optionally by up to 9 space-separated arguments. The name and args are separately expanded. Args go into $acl_arg globals. */ static int acl_check_wargs(int where, address_item *addr, uschar *s, int level, uschar **user_msgptr, uschar **log_msgptr) { uschar * tmp; uschar * tmp_arg[9]; /* must match acl_arg[] */ uschar * name; int i; if (!(tmp = string_dequote(&s)) || !(name = expand_string(tmp))) goto bad; for (i = 0; i < 9; i++) { while (*s && isspace(*s)) s++; if (!*s) break; if (!(tmp = string_dequote(&s)) || !(tmp_arg[i] = expand_string(tmp))) { tmp = name; goto bad; } } acl_narg = i; for (i = 0; i < acl_narg; i++) acl_arg[i] = tmp_arg[i]; while (i < 9) acl_arg[i++] = NULL; return acl_check_internal(where, addr, name, level, user_msgptr, log_msgptr); bad: if (expand_string_forcedfail) return ERROR; *log_msgptr = string_sprintf("failed to expand ACL string \"%s\": %s", tmp, expand_string_message); return search_find_defer?DEFER:ERROR; } /************************************************* * 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; log_reject_target = LOG_MAIN|LOG_REJECT; 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); /* Cutthrough - if requested, and WHERE_RCPT and not yet opened conn as result of recipient-verify, and rcpt acl returned accept, and first recipient (cancel on any subsequents) open one now and run it up to RCPT acceptance. A failed verify should cancel cutthrough request. Initial implementation: dual-write to spool. Assume the rxd datastream is now being copied byte-for-byte to an open cutthrough connection. Cease cutthrough copy on rxd final dot; do not send one. On a data acl, if not accept and a cutthrough conn is open, hard-close it (no SMTP niceness). On data acl accept, terminate the dataphase on an open cutthrough conn. If accepted or perm-rejected, reflect that to the original sender - and dump the spooled copy. If temp-reject, close the conn (and keep the spooled copy). If conn-failure, no action (and keep the spooled copy). */ switch (where) { case ACL_WHERE_RCPT: if( rcpt_count > 1 ) cancel_cutthrough_connection("more than one recipient"); else if (rc == OK && cutthrough_delivery && cutthrough_fd < 0) open_cutthrough_connection(addr); break; case ACL_WHERE_PREDATA: if( rc == OK ) cutthrough_predata(); else cancel_cutthrough_connection("predata acl not ok"); break; case ACL_WHERE_QUIT: case ACL_WHERE_NOTQUIT: cancel_cutthrough_connection("quit or notquit"); break; default: break; } 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 a response, take a look at the length of any user message, and split it up into multiple lines if possible. */ *user_msgptr = string_split_message(*user_msgptr); if (fake_response != OK) fake_response_text = string_split_message(fake_response_text); return rc; } /************************************************* * Create ACL variable * *************************************************/ /* Create an ACL variable or reuse an existing one. ACL variables are in a binary tree (see tree.c) with acl_var_c and acl_var_m as root nodes. Argument: name pointer to the variable's name, starting with c or m Returns the pointer to variable's tree node */ tree_node * acl_var_create(uschar *name) { tree_node *node, **root; root = (name[0] == 'c')? &acl_var_c : &acl_var_m; node = tree_search(*root, name); if (node == NULL) { node = store_get(sizeof(tree_node) + Ustrlen(name)); Ustrcpy(node->name, name); (void)tree_insertnode(root, node); } node->data.ptr = NULL; return node; } /************************************************* * Write an ACL variable in spool format * *************************************************/ /* This function is used as a callback for tree_walk when writing variables to the spool file. To retain spool file compatibility, what is written is -aclc or -aclm followed by the rest of the name and the data length, space separated, then the value itself, starting on a new line, and terminated by an additional newline. When we had only numbered ACL variables, the first line might look like this: "-aclc 5 20". Now it might be "-aclc foo 20" for the variable called acl_cfoo. Arguments: name of the variable value of the variable ctx FILE pointer (as a void pointer) Returns: nothing */ void acl_var_write(uschar *name, uschar *value, void *ctx) { FILE *f = (FILE *)ctx; fprintf(f, "-acl%c %s %d\n%s\n", name[0], name+1, Ustrlen(value), value); } /* End of acl.c */