[exim.git] / src / src / dkim.c

/*************************************************
*     Exim - an Internet mail transport agent    *
*************************************************/

/* Copyright (c) University of Cambridge, 1995 - 2015 */
/* See the file NOTICE for conditions of use and distribution. */

/* Code for DKIM support. Other DKIM relevant code is in
   receive.c, transport.c and transports/smtp.c */

#include "exim.h"

#ifndef DISABLE_DKIM

#include "pdkim/pdkim.h"

pdkim_ctx *dkim_verify_ctx = NULL;
pdkim_signature *dkim_signatures = NULL;
pdkim_signature *dkim_cur_sig = NULL;

static int
dkim_exim_query_dns_txt(char *name, char *answer)
{
dns_answer dnsa;
dns_scan dnss;
dns_record *rr;

lookup_dnssec_authenticated = NULL;
if (dns_lookup(&dnsa, US name, T_TXT, NULL) != DNS_SUCCEED)
  return PDKIM_FAIL;

/* Search for TXT record */

for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
     rr;
     rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
  if (rr->type == T_TXT)
    {
    int rr_offset = 0;
    int answer_offset = 0;

    /* Copy record content to the answer buffer */

    while (rr_offset < rr->size)
      {
      uschar len = rr->data[rr_offset++];
      snprintf(answer + answer_offset,
		PDKIM_DNS_TXT_MAX_RECLEN - answer_offset,
		"%.*s", (int)len, (char *) (rr->data + rr_offset));
      rr_offset += len;
      answer_offset += len;
      if (answer_offset >= PDKIM_DNS_TXT_MAX_RECLEN)
	return PDKIM_FAIL;
      }
    return PDKIM_OK;
    }

return PDKIM_FAIL;
}


void
dkim_exim_verify_init(void)
{
/* Free previous context if there is one */

if (dkim_verify_ctx)
  pdkim_free_ctx(dkim_verify_ctx);

/* Create new context */

dkim_verify_ctx = pdkim_init_verify(PDKIM_INPUT_SMTP, &dkim_exim_query_dns_txt);
dkim_collect_input = !!dkim_verify_ctx;
#ifdef PDKIM_DEBUG
if (dkim_collect_input)
  pdkim_set_debug_stream(dkim_verify_ctx, debug_file);
#endif
}


void
dkim_exim_verify_feed(uschar * data, int len)
{
if (  dkim_collect_input
   && pdkim_feed(dkim_verify_ctx, (char *)data, len) != PDKIM_OK)
  dkim_collect_input = FALSE;
}


void
dkim_exim_verify_finish(void)
{
pdkim_signature *sig = NULL;
int dkim_signers_size = 0;
int dkim_signers_ptr = 0;
dkim_signers = NULL;

/* Delete eventual previous signature chain */

dkim_signatures = NULL;

/* If we have arrived here with dkim_collect_input == FALSE, it
means there was a processing error somewhere along the way.
Log the incident and disable futher verification. */

if (!dkim_collect_input)
  {
  log_write(0, LOG_MAIN,
	     "DKIM: Error while running this message through validation,"
	     " disabling signature verification.");
  dkim_disable_verify = TRUE;
  return;
  }

dkim_collect_input = FALSE;

/* Finish DKIM operation and fetch link to signatures chain */

if (pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures) != PDKIM_OK)
  return;

for (sig = dkim_signatures; sig; sig = sig->next)
  {
  int size = 0;
  int ptr = 0;

  /* Log a line for each signature */

  uschar *logmsg = string_append(NULL, &size, &ptr, 5,
	string_sprintf("d=%s s=%s c=%s/%s a=%s ",
	      sig->domain,
	      sig->selector,
	      sig->canon_headers == PDKIM_CANON_SIMPLE ?  "simple" : "relaxed",
	      sig->canon_body == PDKIM_CANON_SIMPLE ?  "simple" : "relaxed",
	      sig->algo == PDKIM_ALGO_RSA_SHA256 ?  "rsa-sha256" : "rsa-sha1"),

	sig->identity ? string_sprintf("i=%s ", sig->identity) : US"",
	sig->created > 0 ? string_sprintf("t=%lu ", sig->created) : US"",
	sig->expires > 0 ? string_sprintf("x=%lu ", sig->expires) : US"",
	sig->bodylength > -1 ? string_sprintf("l=%lu ", sig->bodylength) : US""
	);

  switch (sig->verify_status)
    {
    case PDKIM_VERIFY_NONE:
      logmsg = string_append(logmsg, &size, &ptr, 1, "[not verified]");
      break;

    case PDKIM_VERIFY_INVALID:
      logmsg = string_append(logmsg, &size, &ptr, 1, "[invalid - ");
      switch (sig->verify_ext_status)
	{
	case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
	  logmsg = string_append(logmsg, &size, &ptr, 1,
		        "public key record (currently?) unavailable]");
	  break;

	case PDKIM_VERIFY_INVALID_BUFFER_SIZE:
	  logmsg = string_append(logmsg, &size, &ptr, 1,
			"overlong public key record]");
	  break;

	case PDKIM_VERIFY_INVALID_PUBKEY_PARSING:
	  logmsg = string_append(logmsg, &size, &ptr, 1,
		       "syntax error in public key record]");
	  break;

	default:
	  logmsg = string_append(logmsg, &size, &ptr, 1,
			"unspecified problem]");
	}
      break;

    case PDKIM_VERIFY_FAIL:
      logmsg =
	string_append(logmsg, &size, &ptr, 1, "[verification failed - ");
      switch (sig->verify_ext_status)
	{
	case PDKIM_VERIFY_FAIL_BODY:
	  logmsg = string_append(logmsg, &size, &ptr, 1,
		       "body hash mismatch (body probably modified in transit)]");
	  break;

	case PDKIM_VERIFY_FAIL_MESSAGE:
	  logmsg = string_append(logmsg, &size, &ptr, 1,
		       "signature did not verify (headers probably modified in transit)]");
	break;

	default:
	  logmsg = string_append(logmsg, &size, &ptr, 1, "unspecified reason]");
	}
      break;

    case PDKIM_VERIFY_PASS:
      logmsg =
	string_append(logmsg, &size, &ptr, 1, "[verification succeeded]");
      break;
    }

  logmsg[ptr] = '\0';
  log_write(0, LOG_MAIN, "DKIM: %s", logmsg);

  /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */

  dkim_signers = string_append(dkim_signers,
				&dkim_signers_size,
				&dkim_signers_ptr, 2, sig->domain, ":");

  if (sig->identity)
    dkim_signers = string_append(dkim_signers,
				  &dkim_signers_size,
				  &dkim_signers_ptr, 2, sig->identity, ":");

  /* Process next signature */
  }

/* NULL-terminate and chop the last colon from the domain list */

if (dkim_signers)
  {
  dkim_signers[dkim_signers_ptr] = '\0';
  if (Ustrlen(dkim_signers) > 0)
  dkim_signers[Ustrlen(dkim_signers) - 1] = '\0';
  }
}


void
dkim_exim_acl_setup(uschar * id)
{
pdkim_signature * sig;
uschar * cmp_val;


dkim_cur_sig = NULL;
dkim_cur_signer = id;

if (dkim_disable_verify || !id || !dkim_verify_ctx)
  return;

/* Find signature to run ACL on */

for (sig = dkim_signatures; sig; sig = sig->next)
  if (  (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain)
     && strcmpic(cmp_val, id) == 0
     )
    {
    dkim_cur_sig = sig;

    /* The "dkim_domain" and "dkim_selector" expansion variables have
       related globals, since they are used in the signing code too.
       Instead of inventing separate names for verification, we set
       them here. This is easy since a domain and selector is guaranteed
       to be in a signature. The other dkim_* expansion items are
       dynamically fetched from dkim_cur_sig at expansion time (see
       function below). */

    dkim_signing_domain = US sig->domain;
    dkim_signing_selector = US sig->selector;
    return;
    }
}


static uschar *
dkim_exim_expand_defaults(int what)
{
switch (what)
  {
  case DKIM_ALGO:		return US"";
  case DKIM_BODYLENGTH:		return US"9999999999999";
  case DKIM_CANON_BODY:		return US"";
  case DKIM_CANON_HEADERS:	return US"";
  case DKIM_COPIEDHEADERS:	return US"";
  case DKIM_CREATED:		return US"0";
  case DKIM_EXPIRES:		return US"9999999999999";
  case DKIM_HEADERNAMES:	return US"";
  case DKIM_IDENTITY:		return US"";
  case DKIM_KEY_GRANULARITY:	return US"*";
  case DKIM_KEY_SRVTYPE:	return US"*";
  case DKIM_KEY_NOTES:		return US"";
  case DKIM_KEY_TESTING:	return US"0";
  case DKIM_NOSUBDOMAINS:	return US"0";
  case DKIM_VERIFY_STATUS:	return US"none";
  case DKIM_VERIFY_REASON:	return US"";
  default:			return US"";
  }
}


uschar *
dkim_exim_expand_query(int what)
{
if (!dkim_verify_ctx || dkim_disable_verify || !dkim_cur_sig)
  return dkim_exim_expand_defaults(what);

switch (what)
  {
  case DKIM_ALGO:
    switch (dkim_cur_sig->algo)
      {
      case PDKIM_ALGO_RSA_SHA1:	return US"rsa-sha1";
      case PDKIM_ALGO_RSA_SHA256:
      default:			return US"rsa-sha256";
      }

  case DKIM_BODYLENGTH:
    return dkim_cur_sig->bodylength >= 0
      ? string_sprintf(OFF_T_FMT, (LONGLONG_T) dkim_cur_sig->bodylength)
      : dkim_exim_expand_defaults(what);

  case DKIM_CANON_BODY:
    switch (dkim_cur_sig->canon_body)
      {
      case PDKIM_CANON_RELAXED:	return US"relaxed";
      case PDKIM_CANON_SIMPLE:
      default:			return US"simple";
      }

  case DKIM_CANON_HEADERS:
  switch (dkim_cur_sig->canon_headers)
    {
    case PDKIM_CANON_RELAXED:	return US"relaxed";
    case PDKIM_CANON_SIMPLE:
    default:			return US"simple";
    }

  case DKIM_COPIEDHEADERS:
    return dkim_cur_sig->copiedheaders
      ? US dkim_cur_sig->copiedheaders : dkim_exim_expand_defaults(what);

  case DKIM_CREATED:
    return dkim_cur_sig->created > 0
      ? string_sprintf("%llu", dkim_cur_sig->created)
      : dkim_exim_expand_defaults(what);

  case DKIM_EXPIRES:
    return dkim_cur_sig->expires > 0
      ? string_sprintf("%llu", dkim_cur_sig->expires)
      : dkim_exim_expand_defaults(what);

  case DKIM_HEADERNAMES:
    return dkim_cur_sig->headernames
      ?  US dkim_cur_sig->headernames : dkim_exim_expand_defaults(what);

  case DKIM_IDENTITY:
    return dkim_cur_sig->identity
      ? US dkim_cur_sig->identity : dkim_exim_expand_defaults(what);

  case DKIM_KEY_GRANULARITY:
    return dkim_cur_sig->pubkey
      ? dkim_cur_sig->pubkey->granularity
      ? US dkim_cur_sig->pubkey->granularity
      : dkim_exim_expand_defaults(what)
      : dkim_exim_expand_defaults(what);

  case DKIM_KEY_SRVTYPE:
    return dkim_cur_sig->pubkey
      ? dkim_cur_sig->pubkey->srvtype
      ? US dkim_cur_sig->pubkey->srvtype
      : dkim_exim_expand_defaults(what)
      : dkim_exim_expand_defaults(what);

  case DKIM_KEY_NOTES:
    return dkim_cur_sig->pubkey
      ? dkim_cur_sig->pubkey->notes
      ? US dkim_cur_sig->pubkey->notes
      : dkim_exim_expand_defaults(what)
      : dkim_exim_expand_defaults(what);

  case DKIM_KEY_TESTING:
    return dkim_cur_sig->pubkey
      ? dkim_cur_sig->pubkey->testing
      ? US"1"
      : dkim_exim_expand_defaults(what)
      : dkim_exim_expand_defaults(what);

  case DKIM_NOSUBDOMAINS:
    return dkim_cur_sig->pubkey
      ? dkim_cur_sig->pubkey->no_subdomaining
      ? US"1"
      : dkim_exim_expand_defaults(what)
      : dkim_exim_expand_defaults(what);

  case DKIM_VERIFY_STATUS:
    switch (dkim_cur_sig->verify_status)
      {
      case PDKIM_VERIFY_INVALID:	return US"invalid";
      case PDKIM_VERIFY_FAIL:		return US"fail";
      case PDKIM_VERIFY_PASS:		return US"pass";
      case PDKIM_VERIFY_NONE:
      default:				return US"none";
      }

  case DKIM_VERIFY_REASON:
    switch (dkim_cur_sig->verify_ext_status)
      {
      case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
						return US"pubkey_unavailable";
      case PDKIM_VERIFY_INVALID_PUBKEY_PARSING:	return US"pubkey_syntax";
      case PDKIM_VERIFY_FAIL_BODY:		return US"bodyhash_mismatch";
      case PDKIM_VERIFY_FAIL_MESSAGE:		return US"signature_incorrect";
      }

  default:
    return US"";
  }
}


uschar *
dkim_exim_sign(int dkim_fd, uschar * dkim_private_key,
		const uschar * dkim_domain, uschar * dkim_selector,
		uschar * dkim_canon, uschar * dkim_sign_headers)
{
int sep = 0;
uschar *seen_items = NULL;
int seen_items_size = 0;
int seen_items_offset = 0;
uschar itembuf[256];
uschar *dkim_canon_expanded;
uschar *dkim_sign_headers_expanded;
uschar *dkim_private_key_expanded;
pdkim_ctx *ctx = NULL;
uschar *rc = NULL;
uschar *sigbuf = NULL;
int sigsize = 0;
int sigptr = 0;
pdkim_signature *signature;
int pdkim_canon;
int pdkim_rc;
int sread;
char buf[4096];
int save_errno = 0;
int old_pool = store_pool;

store_pool = POOL_MAIN;

if (!(dkim_domain = expand_cstring(dkim_domain)))
  {
  /* expansion error, do not send message. */
  log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand "
	     "dkim_domain: %s", expand_string_message);
  rc = NULL;
  goto CLEANUP;
  }

/* Set $dkim_domain expansion variable to each unique domain in list. */

while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep,
				   itembuf, sizeof(itembuf))))
  {
  if (!dkim_signing_domain || dkim_signing_domain[0] == '\0')
    continue;

  /* Only sign once for each domain, no matter how often it
  appears in the expanded list. */

  if (seen_items)
    {
    const uschar *seen_items_list = seen_items;
    if (match_isinlist(dkim_signing_domain,
			&seen_items_list, 0, NULL, NULL, MCL_STRING, TRUE,
			NULL) == OK)
      continue;

    seen_items =
      string_append(seen_items, &seen_items_size, &seen_items_offset, 1, ":");
    }

  seen_items =
    string_append(seen_items, &seen_items_size, &seen_items_offset, 1,
		 dkim_signing_domain);
  seen_items[seen_items_offset] = '\0';

  /* Set up $dkim_selector expansion variable. */

  if (!(dkim_signing_selector = expand_string(dkim_selector)))
    {
    log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand "
	       "dkim_selector: %s", expand_string_message);
    rc = NULL;
    goto CLEANUP;
    }

  /* Get canonicalization to use */

  dkim_canon_expanded = dkim_canon ? expand_string(dkim_canon) : US"relaxed";
  if (!dkim_canon_expanded)
    {
    /* expansion error, do not send message. */
    log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand "
	       "dkim_canon: %s", expand_string_message);
    rc = NULL;
    goto CLEANUP;
    }

  if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0)
    pdkim_canon = PDKIM_CANON_RELAXED;
  else if (Ustrcmp(dkim_canon_expanded, "simple") == 0)
    pdkim_canon = PDKIM_CANON_SIMPLE;
  else
    {
    log_write(0, LOG_MAIN,
	       "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n",
	       dkim_canon_expanded);
    pdkim_canon = PDKIM_CANON_RELAXED;
    }

  dkim_sign_headers_expanded = NULL;
  if (dkim_sign_headers)
    if (!(dkim_sign_headers_expanded = expand_string(dkim_sign_headers)))
      {
      log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand "
		 "dkim_sign_headers: %s", expand_string_message);
      rc = NULL;
      goto CLEANUP;
      }
    			/* else pass NULL, which means default header list */

  /* Get private key to use. */

  if (!(dkim_private_key_expanded = expand_string(dkim_private_key)))
    {
    log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand "
	       "dkim_private_key: %s", expand_string_message);
    rc = NULL;
    goto CLEANUP;
    }

  if (  Ustrlen(dkim_private_key_expanded) == 0
     || Ustrcmp(dkim_private_key_expanded, "0") == 0
     || Ustrcmp(dkim_private_key_expanded, "false") == 0
     )
    continue;		/* don't sign, but no error */

  if (dkim_private_key_expanded[0] == '/')
    {
    int privkey_fd = 0;

    /* Looks like a filename, load the private key. */

    memset(big_buffer, 0, big_buffer_size);
    privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY);
    if (privkey_fd < 0)
      {
      log_write(0, LOG_MAIN | LOG_PANIC, "unable to open "
		 "private key file for reading: %s",
		 dkim_private_key_expanded);
      rc = NULL;
      goto CLEANUP;
      }

    if (read(privkey_fd, big_buffer, big_buffer_size - 2) < 0)
      {
      log_write(0, LOG_MAIN|LOG_PANIC, "unable to read private key file: %s",
		 dkim_private_key_expanded);
      rc = NULL;
      goto CLEANUP;
      }

    (void) close(privkey_fd);
    dkim_private_key_expanded = big_buffer;
    }

  ctx = pdkim_init_sign(PDKIM_INPUT_SMTP,
			 (char *) dkim_signing_domain,
			 (char *) dkim_signing_selector,
			 (char *) dkim_private_key_expanded);
#ifdef PDKIM_DEBUG
  pdkim_set_debug_stream(ctx, debug_file);
#endif
  pdkim_set_optional(ctx,
		      (char *) dkim_sign_headers_expanded,
		      NULL,
		      pdkim_canon,
		      pdkim_canon, -1, PDKIM_ALGO_RSA_SHA256, 0, 0);

  lseek(dkim_fd, 0, SEEK_SET);

  while ((sread = read(dkim_fd, &buf, 4096)) > 0)
    if (pdkim_feed(ctx, buf, sread) != PDKIM_OK)
      {
      rc = NULL;
      goto CLEANUP;
      }

  /* Handle failed read above. */
  if (sread == -1)
    {
    debug_printf("DKIM: Error reading -K file.\n");
    save_errno = errno;
    rc = NULL;
    goto CLEANUP;
    }

  if ((pdkim_rc = pdkim_feed_finish(ctx, &signature)) != PDKIM_OK)
    {
    log_write(0, LOG_MAIN|LOG_PANIC, "DKIM: signing failed (RC %d)", pdkim_rc);
    rc = NULL;
    goto CLEANUP;
    }

  sigbuf = string_append(sigbuf, &sigsize, &sigptr, 2,
			  US signature->signature_header, US"\r\n");

  pdkim_free_ctx(ctx);
  ctx = NULL;
  }

if (sigbuf)
  {
  sigbuf[sigptr] = '\0';
  rc = sigbuf;
  }
else
  rc = US"";

CLEANUP:
if (ctx)
  pdkim_free_ctx(ctx);
store_pool = old_pool;
errno = save_errno;
return rc;
}

#endif
Commit	Line	Data
80a47a2c TK	1	/*************************************************
	2	* Exim - an Internet mail transport agent *
	3	*************************************************/
	4
3386088d	5	/* Copyright (c) University of Cambridge, 1995 - 2015 */
80a47a2c TK	6	/* See the file NOTICE for conditions of use and distribution. */
	7
	8	/* Code for DKIM support. Other DKIM relevant code is in
	9	receive.c, transport.c and transports/smtp.c */
	10
	11	#include "exim.h"
	12
	13	#ifndef DISABLE_DKIM
	14
	15	#include "pdkim/pdkim.h"
	16
1cfe5c1c	17	pdkim_ctx *dkim_verify_ctx = NULL;
80a47a2c	18	pdkim_signature *dkim_signatures = NULL;
1cfe5c1c	19	pdkim_signature *dkim_cur_sig = NULL;
80a47a2c	20
1cfe5c1c JH	21	static int
	22	dkim_exim_query_dns_txt(char name, char answer)
	23	{
	24	dns_answer dnsa;
	25	dns_scan dnss;
	26	dns_record *rr;
80a47a2c	27
1cfe5c1c JH	28	lookup_dnssec_authenticated = NULL;
	29	if (dns_lookup(&dnsa, US name, T_TXT, NULL) != DNS_SUCCEED)
	30	return PDKIM_FAIL;
80a47a2c	31
1cfe5c1c	32	/* Search for TXT record */
80a47a2c	33
1cfe5c1c JH	34	for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
	35	rr;
	36	rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
	37	if (rr->type == T_TXT)
	38	{
80a47a2c TK	39	int rr_offset = 0;
80a47a2c TK	40	int answer_offset = 0;
1cfe5c1c JH	41
	42	/* Copy record content to the answer buffer */
	43
	44	while (rr_offset < rr->size)
	45	{
	46	uschar len = rr->data[rr_offset++];
	47	snprintf(answer + answer_offset,
	48	PDKIM_DNS_TXT_MAX_RECLEN - answer_offset,
	49	"%.s", (int)len, (char ) (rr->data + rr_offset));
	50	rr_offset += len;
	51	answer_offset += len;
	52	if (answer_offset >= PDKIM_DNS_TXT_MAX_RECLEN)
	53	return PDKIM_FAIL;
4263f395	54	}
1cfe5c1c	55	return PDKIM_OK;
80a47a2c	56	}
80a47a2c	57
1cfe5c1c	58	return PDKIM_FAIL;
80a47a2c TK	59	}
	60
	61
1cfe5c1c JH	62	void
	63	dkim_exim_verify_init(void)
	64	{
	65	/* Free previous context if there is one */
80a47a2c	66
1cfe5c1c JH	67	if (dkim_verify_ctx)
1cfe5c1c JH	68	pdkim_free_ctx(dkim_verify_ctx);
80a47a2c	69
1cfe5c1c	70	/* Create new context */
80a47a2c	71
1cfe5c1c	72	dkim_verify_ctx = pdkim_init_verify(PDKIM_INPUT_SMTP, &dkim_exim_query_dns_txt);
3b957582 JB	73	dkim_collect_input = !!dkim_verify_ctx;
	74	#ifdef PDKIM_DEBUG
	75	if (dkim_collect_input)
1cfe5c1c	76	pdkim_set_debug_stream(dkim_verify_ctx, debug_file);
3b957582	77	#endif
80a47a2c TK	78	}
	79
	80
1cfe5c1c JH	81	void
	82	dkim_exim_verify_feed(uschar * data, int len)
	83	{
	84	if ( dkim_collect_input
	85	&& pdkim_feed(dkim_verify_ctx, (char *)data, len) != PDKIM_OK)
	86	dkim_collect_input = FALSE;
80a47a2c TK	87	}
	88
	89
1cfe5c1c JH	90	void
	91	dkim_exim_verify_finish(void)
	92	{
	93	pdkim_signature *sig = NULL;
	94	int dkim_signers_size = 0;
	95	int dkim_signers_ptr = 0;
	96	dkim_signers = NULL;
	97
	98	/* Delete eventual previous signature chain */
	99
	100	dkim_signatures = NULL;
	101
	102	/* If we have arrived here with dkim_collect_input == FALSE, it
	103	means there was a processing error somewhere along the way.
	104	Log the incident and disable futher verification. */
	105
	106	if (!dkim_collect_input)
	107	{
	108	log_write(0, LOG_MAIN,
	109	"DKIM: Error while running this message through validation,"
	110	" disabling signature verification.");
	111	dkim_disable_verify = TRUE;
	112	return;
	113	}
80a47a2c	114
1cfe5c1c	115	dkim_collect_input = FALSE;
80a47a2c	116
1cfe5c1c	117	/* Finish DKIM operation and fetch link to signatures chain */
80a47a2c	118
1cfe5c1c JH	119	if (pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures) != PDKIM_OK)
	120	return;
	121
	122	for (sig = dkim_signatures; sig; sig = sig->next)
	123	{
	124	int size = 0;
	125	int ptr = 0;
	126
	127	/* Log a line for each signature */
	128
	129	uschar *logmsg = string_append(NULL, &size, &ptr, 5,
	130	string_sprintf("d=%s s=%s c=%s/%s a=%s ",
	131	sig->domain,
	132	sig->selector,
	133	sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
	134	sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
	135	sig->algo == PDKIM_ALGO_RSA_SHA256 ? "rsa-sha256" : "rsa-sha1"),
	136
	137	sig->identity ? string_sprintf("i=%s ", sig->identity) : US"",
	138	sig->created > 0 ? string_sprintf("t=%lu ", sig->created) : US"",
	139	sig->expires > 0 ? string_sprintf("x=%lu ", sig->expires) : US"",
	140	sig->bodylength > -1 ? string_sprintf("l=%lu ", sig->bodylength) : US""
	141	);
	142
	143	switch (sig->verify_status)
	144	{
	145	case PDKIM_VERIFY_NONE:
	146	logmsg = string_append(logmsg, &size, &ptr, 1, "[not verified]");
80a47a2c	147	break;
1cfe5c1c JH	148
	149	case PDKIM_VERIFY_INVALID:
	150	logmsg = string_append(logmsg, &size, &ptr, 1, "[invalid - ");
	151	switch (sig->verify_ext_status)
	152	{
	153	case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
	154	logmsg = string_append(logmsg, &size, &ptr, 1,
	155	"public key record (currently?) unavailable]");
	156	break;
	157
	158	case PDKIM_VERIFY_INVALID_BUFFER_SIZE:
	159	logmsg = string_append(logmsg, &size, &ptr, 1,
	160	"overlong public key record]");
	161	break;
	162
	163	case PDKIM_VERIFY_INVALID_PUBKEY_PARSING:
	164	logmsg = string_append(logmsg, &size, &ptr, 1,
	165	"syntax error in public key record]");
	166	break;
	167
	168	default:
	169	logmsg = string_append(logmsg, &size, &ptr, 1,
	170	"unspecified problem]");
	171	}
80a47a2c	172	break;
1cfe5c1c JH	173
	174	case PDKIM_VERIFY_FAIL:
	175	logmsg =
	176	string_append(logmsg, &size, &ptr, 1, "[verification failed - ");
	177	switch (sig->verify_ext_status)
	178	{
	179	case PDKIM_VERIFY_FAIL_BODY:
	180	logmsg = string_append(logmsg, &size, &ptr, 1,
	181	"body hash mismatch (body probably modified in transit)]");
	182	break;
	183
	184	case PDKIM_VERIFY_FAIL_MESSAGE:
	185	logmsg = string_append(logmsg, &size, &ptr, 1,
	186	"signature did not verify (headers probably modified in transit)]");
	187	break;
	188
	189	default:
	190	logmsg = string_append(logmsg, &size, &ptr, 1, "unspecified reason]");
	191	}
80a47a2c	192	break;
1cfe5c1c JH	193
	194	case PDKIM_VERIFY_PASS:
	195	logmsg =
	196	string_append(logmsg, &size, &ptr, 1, "[verification succeeded]");
80a47a2c TK	197	break;
	198	}
	199
1cfe5c1c JH	200	logmsg[ptr] = '\0';
1cfe5c1c JH	201	log_write(0, LOG_MAIN, "DKIM: %s", logmsg);
80a47a2c	202
1cfe5c1c JH	203	/* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */
	204
	205	dkim_signers = string_append(dkim_signers,
	206	&dkim_signers_size,
	207	&dkim_signers_ptr, 2, sig->domain, ":");
	208
	209	if (sig->identity)
9e5d6b55	210	dkim_signers = string_append(dkim_signers,
1cfe5c1c JH	211	&dkim_signers_size,
1cfe5c1c JH	212	&dkim_signers_ptr, 2, sig->identity, ":");
80a47a2c	213
1cfe5c1c	214	/* Process next signature */
80a47a2c TK	215	}
80a47a2c TK	216
1cfe5c1c JH	217	/* NULL-terminate and chop the last colon from the domain list */
	218
	219	if (dkim_signers)
	220	{
	221	dkim_signers[dkim_signers_ptr] = '\0';
	222	if (Ustrlen(dkim_signers) > 0)
	223	dkim_signers[Ustrlen(dkim_signers) - 1] = '\0';
0d2b278d	224	}
80a47a2c TK	225	}
	226
	227
1cfe5c1c JH	228	void
	229	dkim_exim_acl_setup(uschar * id)
	230	{
	231	pdkim_signature * sig;
	232	uschar * cmp_val;
	233
	234
	235	dkim_cur_sig = NULL;
	236	dkim_cur_signer = id;
	237
	238	if (dkim_disable_verify \|\| !id \|\| !dkim_verify_ctx)
	239	return;
	240
	241	/* Find signature to run ACL on */
	242
	243	for (sig = dkim_signatures; sig; sig = sig->next)
	244	if ( (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain)
	245	&& strcmpic(cmp_val, id) == 0
	246	)
	247	{
	248	dkim_cur_sig = sig;
	249
	250	/* The "dkim_domain" and "dkim_selector" expansion variables have
	251	related globals, since they are used in the signing code too.
	252	Instead of inventing separate names for verification, we set
	253	them here. This is easy since a domain and selector is guaranteed
	254	to be in a signature. The other dkim_* expansion items are
	255	dynamically fetched from dkim_cur_sig at expansion time (see
	256	function below). */
	257
	258	dkim_signing_domain = US sig->domain;
	259	dkim_signing_selector = US sig->selector;
	260	return;
80a47a2c	261	}
80a47a2c TK	262	}
	263
	264
1cfe5c1c JH	265	static uschar *
	266	dkim_exim_expand_defaults(int what)
	267	{
	268	switch (what)
	269	{
	270	case DKIM_ALGO: return US"";
	271	case DKIM_BODYLENGTH: return US"9999999999999";
	272	case DKIM_CANON_BODY: return US"";
	273	case DKIM_CANON_HEADERS: return US"";
	274	case DKIM_COPIEDHEADERS: return US"";
	275	case DKIM_CREATED: return US"0";
	276	case DKIM_EXPIRES: return US"9999999999999";
	277	case DKIM_HEADERNAMES: return US"";
	278	case DKIM_IDENTITY: return US"";
	279	case DKIM_KEY_GRANULARITY: return US"*";
	280	case DKIM_KEY_SRVTYPE: return US"*";
	281	case DKIM_KEY_NOTES: return US"";
	282	case DKIM_KEY_TESTING: return US"0";
	283	case DKIM_NOSUBDOMAINS: return US"0";
	284	case DKIM_VERIFY_STATUS: return US"none";
	285	case DKIM_VERIFY_REASON: return US"";
	286	default: return US"";
	287	}
	288	}
80a47a2c	289
80a47a2c	290
1cfe5c1c JH	291	uschar *
	292	dkim_exim_expand_query(int what)
	293	{
	294	if (!dkim_verify_ctx \|\| dkim_disable_verify \|\| !dkim_cur_sig)
	295	return dkim_exim_expand_defaults(what);
	296
	297	switch (what)
	298	{
	299	case DKIM_ALGO:
	300	switch (dkim_cur_sig->algo)
	301	{
	302	case PDKIM_ALGO_RSA_SHA1: return US"rsa-sha1";
	303	case PDKIM_ALGO_RSA_SHA256:
	304	default: return US"rsa-sha256";
da5dfc3a	305	}
1cfe5c1c JH	306
	307	case DKIM_BODYLENGTH:
	308	return dkim_cur_sig->bodylength >= 0
	309	? string_sprintf(OFF_T_FMT, (LONGLONG_T) dkim_cur_sig->bodylength)
	310	: dkim_exim_expand_defaults(what);
	311
	312	case DKIM_CANON_BODY:
	313	switch (dkim_cur_sig->canon_body)
	314	{
	315	case PDKIM_CANON_RELAXED: return US"relaxed";
	316	case PDKIM_CANON_SIMPLE:
	317	default: return US"simple";
80a47a2c	318	}
1cfe5c1c JH	319
	320	case DKIM_CANON_HEADERS:
	321	switch (dkim_cur_sig->canon_headers)
	322	{
	323	case PDKIM_CANON_RELAXED: return US"relaxed";
	324	case PDKIM_CANON_SIMPLE:
	325	default: return US"simple";
	326	}
	327
	328	case DKIM_COPIEDHEADERS:
	329	return dkim_cur_sig->copiedheaders
	330	? US dkim_cur_sig->copiedheaders : dkim_exim_expand_defaults(what);
	331
	332	case DKIM_CREATED:
	333	return dkim_cur_sig->created > 0
	334	? string_sprintf("%llu", dkim_cur_sig->created)
	335	: dkim_exim_expand_defaults(what);
	336
	337	case DKIM_EXPIRES:
	338	return dkim_cur_sig->expires > 0
	339	? string_sprintf("%llu", dkim_cur_sig->expires)
	340	: dkim_exim_expand_defaults(what);
	341
	342	case DKIM_HEADERNAMES:
	343	return dkim_cur_sig->headernames
	344	? US dkim_cur_sig->headernames : dkim_exim_expand_defaults(what);
	345
	346	case DKIM_IDENTITY:
	347	return dkim_cur_sig->identity
	348	? US dkim_cur_sig->identity : dkim_exim_expand_defaults(what);
	349
	350	case DKIM_KEY_GRANULARITY:
	351	return dkim_cur_sig->pubkey
	352	? dkim_cur_sig->pubkey->granularity
	353	? US dkim_cur_sig->pubkey->granularity
	354	: dkim_exim_expand_defaults(what)
	355	: dkim_exim_expand_defaults(what);
	356
	357	case DKIM_KEY_SRVTYPE:
	358	return dkim_cur_sig->pubkey
	359	? dkim_cur_sig->pubkey->srvtype
	360	? US dkim_cur_sig->pubkey->srvtype
	361	: dkim_exim_expand_defaults(what)
	362	: dkim_exim_expand_defaults(what);
	363
	364	case DKIM_KEY_NOTES:
	365	return dkim_cur_sig->pubkey
	366	? dkim_cur_sig->pubkey->notes
	367	? US dkim_cur_sig->pubkey->notes
	368	: dkim_exim_expand_defaults(what)
	369	: dkim_exim_expand_defaults(what);
	370
	371	case DKIM_KEY_TESTING:
	372	return dkim_cur_sig->pubkey
	373	? dkim_cur_sig->pubkey->testing
	374	? US"1"
	375	: dkim_exim_expand_defaults(what)
	376	: dkim_exim_expand_defaults(what);
	377
	378	case DKIM_NOSUBDOMAINS:
	379	return dkim_cur_sig->pubkey
	380	? dkim_cur_sig->pubkey->no_subdomaining
	381	? US"1"
	382	: dkim_exim_expand_defaults(what)
383	: dkim_exim_expand_defaults(what);
384
385	case DKIM_VERIFY_STATUS:
386	switch (dkim_cur_sig->verify_status)
387	{
388	case PDKIM_VERIFY_INVALID: return US"invalid";
389	case PDKIM_VERIFY_FAIL: return US"fail";
390	case PDKIM_VERIFY_PASS: return US"pass";
391	case PDKIM_VERIFY_NONE:
392	default: return US"none";
80a47a2c	393	}
80a47a2c	394
1cfe5c1c JH	395	case DKIM_VERIFY_REASON:
	396	switch (dkim_cur_sig->verify_ext_status)
	397	{
	398	case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
	399	return US"pubkey_unavailable";
	400	case PDKIM_VERIFY_INVALID_PUBKEY_PARSING: return US"pubkey_syntax";
	401	case PDKIM_VERIFY_FAIL_BODY: return US"bodyhash_mismatch";
	402	case PDKIM_VERIFY_FAIL_MESSAGE: return US"signature_incorrect";
	403	}
80a47a2c	404
1cfe5c1c JH	405	default:
1cfe5c1c JH	406	return US"";
80a47a2c TK	407	}
	408	}
	409
	410
55414b25	411	uschar *
1cfe5c1c JH	412	dkim_exim_sign(int dkim_fd, uschar * dkim_private_key,
	413	const uschar * dkim_domain, uschar * dkim_selector,
	414	uschar * dkim_canon, uschar * dkim_sign_headers)
55414b25	415	{
1cfe5c1c JH	416	int sep = 0;
	417	uschar *seen_items = NULL;
	418	int seen_items_size = 0;
	419	int seen_items_offset = 0;
	420	uschar itembuf[256];
	421	uschar *dkim_canon_expanded;
	422	uschar *dkim_sign_headers_expanded;
	423	uschar *dkim_private_key_expanded;
	424	pdkim_ctx *ctx = NULL;
	425	uschar *rc = NULL;
	426	uschar *sigbuf = NULL;
	427	int sigsize = 0;
	428	int sigptr = 0;
	429	pdkim_signature *signature;
	430	int pdkim_canon;
	431	int pdkim_rc;
	432	int sread;
	433	char buf[4096];
	434	int save_errno = 0;
	435	int old_pool = store_pool;
	436
	437	store_pool = POOL_MAIN;
	438
	439	if (!(dkim_domain = expand_cstring(dkim_domain)))
	440	{
	441	/* expansion error, do not send message. */
	442	log_write(0, LOG_MAIN \| LOG_PANIC, "failed to expand "
	443	"dkim_domain: %s", expand_string_message);
	444	rc = NULL;
	445	goto CLEANUP;
	446	}
	447
	448	/* Set $dkim_domain expansion variable to each unique domain in list. */
	449
	450	while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep,
	451	itembuf, sizeof(itembuf))))
	452	{
	453	if (!dkim_signing_domain \|\| dkim_signing_domain[0] == '\0')
	454	continue;
	455
	456	/* Only sign once for each domain, no matter how often it
	457	appears in the expanded list. */
	458
	459	if (seen_items)
	460	{
	461	const uschar *seen_items_list = seen_items;
	462	if (match_isinlist(dkim_signing_domain,
	463	&seen_items_list, 0, NULL, NULL, MCL_STRING, TRUE,
	464	NULL) == OK)
	465	continue;
	466
	467	seen_items =
	468	string_append(seen_items, &seen_items_size, &seen_items_offset, 1, ":");
	469	}
	470
	471	seen_items =
	472	string_append(seen_items, &seen_items_size, &seen_items_offset, 1,
	473	dkim_signing_domain);
	474	seen_items[seen_items_offset] = '\0';
	475
	476	/* Set up $dkim_selector expansion variable. */
	477
	478	if (!(dkim_signing_selector = expand_string(dkim_selector)))
	479	{
480	log_write(0, LOG_MAIN \| LOG_PANIC, "failed to expand "
481	"dkim_selector: %s", expand_string_message);
482	rc = NULL;
483	goto CLEANUP;
484	}
485
486	/* Get canonicalization to use */
487
488	dkim_canon_expanded = dkim_canon ? expand_string(dkim_canon) : US"relaxed";
489	if (!dkim_canon_expanded)
490	{
80a47a2c	491	/* expansion error, do not send message. */
1cfe5c1c JH	492	log_write(0, LOG_MAIN \| LOG_PANIC, "failed to expand "
1cfe5c1c JH	493	"dkim_canon: %s", expand_string_message);
80a47a2c TK	494	rc = NULL;
80a47a2c TK	495	goto CLEANUP;
1cfe5c1c	496	}
80a47a2c	497
1cfe5c1c JH	498	if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0)
	499	pdkim_canon = PDKIM_CANON_RELAXED;
	500	else if (Ustrcmp(dkim_canon_expanded, "simple") == 0)
	501	pdkim_canon = PDKIM_CANON_SIMPLE;
	502	else
	503	{
	504	log_write(0, LOG_MAIN,
	505	"DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n",
	506	dkim_canon_expanded);
	507	pdkim_canon = PDKIM_CANON_RELAXED;
a8e1eeba	508	}
1cfe5c1c JH	509
	510	dkim_sign_headers_expanded = NULL;
	511	if (dkim_sign_headers)
	512	if (!(dkim_sign_headers_expanded = expand_string(dkim_sign_headers)))
	513	{
	514	log_write(0, LOG_MAIN \| LOG_PANIC, "failed to expand "
	515	"dkim_sign_headers: %s", expand_string_message);
a8e1eeba MH	516	rc = NULL;
a8e1eeba MH	517	goto CLEANUP;
1cfe5c1c JH	518	}
	519	/* else pass NULL, which means default header list */
	520
	521	/* Get private key to use. */
	522
	523	if (!(dkim_private_key_expanded = expand_string(dkim_private_key)))
	524	{
	525	log_write(0, LOG_MAIN \| LOG_PANIC, "failed to expand "
	526	"dkim_private_key: %s", expand_string_message);
	527	rc = NULL;
	528	goto CLEANUP;
a8e1eeba	529	}
80a47a2c	530
1cfe5c1c JH	531	if ( Ustrlen(dkim_private_key_expanded) == 0
	532	\|\| Ustrcmp(dkim_private_key_expanded, "0") == 0
	533	\|\| Ustrcmp(dkim_private_key_expanded, "false") == 0
	534	)
	535	continue; /* don't sign, but no error */
	536
	537	if (dkim_private_key_expanded[0] == '/')
	538	{
	539	int privkey_fd = 0;
	540
	541	/* Looks like a filename, load the private key. */
	542
	543	memset(big_buffer, 0, big_buffer_size);
	544	privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY);
	545	if (privkey_fd < 0)
	546	{
	547	log_write(0, LOG_MAIN \| LOG_PANIC, "unable to open "
	548	"private key file for reading: %s",
	549	dkim_private_key_expanded);
80a47a2c TK	550	rc = NULL;
80a47a2c TK	551	goto CLEANUP;
db4d0902	552	}
80a47a2c	553
1cfe5c1c JH	554	if (read(privkey_fd, big_buffer, big_buffer_size - 2) < 0)
	555	{
	556	log_write(0, LOG_MAIN\|LOG_PANIC, "unable to read private key file: %s",
	557	dkim_private_key_expanded);
cf745305 TK	558	rc = NULL;
cf745305 TK	559	goto CLEANUP;
1ac6b2e7	560	}
80a47a2c	561
1cfe5c1c JH	562	(void) close(privkey_fd);
1cfe5c1c JH	563	dkim_private_key_expanded = big_buffer;
a8e1eeba	564	}
1cfe5c1c JH	565
	566	ctx = pdkim_init_sign(PDKIM_INPUT_SMTP,
	567	(char *) dkim_signing_domain,
	568	(char *) dkim_signing_selector,
	569	(char *) dkim_private_key_expanded);
3b957582	570	#ifdef PDKIM_DEBUG
1cfe5c1c	571	pdkim_set_debug_stream(ctx, debug_file);
3b957582	572	#endif
1cfe5c1c JH	573	pdkim_set_optional(ctx,
	574	(char *) dkim_sign_headers_expanded,
	575	NULL,
	576	pdkim_canon,
	577	pdkim_canon, -1, PDKIM_ALGO_RSA_SHA256, 0, 0);
	578
	579	lseek(dkim_fd, 0, SEEK_SET);
	580
	581	while ((sread = read(dkim_fd, &buf, 4096)) > 0)
	582	if (pdkim_feed(ctx, buf, sread) != PDKIM_OK)
	583	{
80a47a2c TK	584	rc = NULL;
80a47a2c TK	585	goto CLEANUP;
1cfe5c1c JH	586	}
	587
	588	/* Handle failed read above. */
	589	if (sread == -1)
	590	{
	591	debug_printf("DKIM: Error reading -K file.\n");
	592	save_errno = errno;
	593	rc = NULL;
	594	goto CLEANUP;
80a47a2c	595	}
80a47a2c	596
1cfe5c1c JH	597	if ((pdkim_rc = pdkim_feed_finish(ctx, &signature)) != PDKIM_OK)
	598	{
	599	log_write(0, LOG_MAIN\|LOG_PANIC, "DKIM: signing failed (RC %d)", pdkim_rc);
	600	rc = NULL;
	601	goto CLEANUP;
a8e1eeba	602	}
80a47a2c	603
1cfe5c1c JH	604	sigbuf = string_append(sigbuf, &sigsize, &sigptr, 2,
1cfe5c1c JH	605	US signature->signature_header, US"\r\n");
80a47a2c	606
1cfe5c1c JH	607	pdkim_free_ctx(ctx);
1cfe5c1c JH	608	ctx = NULL;
80a47a2c	609	}
a8e1eeba	610
1cfe5c1c JH	611	if (sigbuf)
	612	{
	613	sigbuf[sigptr] = '\0';
	614	rc = sigbuf;
	615	}
	616	else
	617	rc = US"";
	618
	619	CLEANUP:
	620	if (ctx)
	621	pdkim_free_ctx(ctx);
	622	store_pool = old_pool;
	623	errno = save_errno;
	624	return rc;
93f2d376	625	}
80a47a2c TK	626
80a47a2c TK	627	#endif