[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(&dkim_exim_query_dns_txt);
dkim_collect_input = !!dkim_verify_ctx;
}


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 b=%d ",
	      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->sigdata_len * 8
	      ),

	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;
    dkim_key_length = sig->sigdata_len * 8;
    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( (char *) dkim_signing_domain,
			 (char *) dkim_signing_selector,
			 (char *) dkim_private_key_expanded);
  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
0d04a285	72	dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt);
3b957582	73	dkim_collect_input = !!dkim_verify_ctx;
80a47a2c TK	74	}
	75
	76
1cfe5c1c JH	77	void
	78	dkim_exim_verify_feed(uschar * data, int len)
	79	{
	80	if ( dkim_collect_input
	81	&& pdkim_feed(dkim_verify_ctx, (char *)data, len) != PDKIM_OK)
	82	dkim_collect_input = FALSE;
80a47a2c TK	83	}
	84
	85
1cfe5c1c JH	86	void
	87	dkim_exim_verify_finish(void)
	88	{
	89	pdkim_signature *sig = NULL;
	90	int dkim_signers_size = 0;
	91	int dkim_signers_ptr = 0;
	92	dkim_signers = NULL;
	93
	94	/* Delete eventual previous signature chain */
	95
	96	dkim_signatures = NULL;
	97
	98	/* If we have arrived here with dkim_collect_input == FALSE, it
	99	means there was a processing error somewhere along the way.
	100	Log the incident and disable futher verification. */
	101
	102	if (!dkim_collect_input)
	103	{
	104	log_write(0, LOG_MAIN,
	105	"DKIM: Error while running this message through validation,"
	106	" disabling signature verification.");
	107	dkim_disable_verify = TRUE;
	108	return;
	109	}
80a47a2c	110
1cfe5c1c	111	dkim_collect_input = FALSE;
80a47a2c	112
1cfe5c1c	113	/* Finish DKIM operation and fetch link to signatures chain */
80a47a2c	114
1cfe5c1c JH	115	if (pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures) != PDKIM_OK)
	116	return;
	117
	118	for (sig = dkim_signatures; sig; sig = sig->next)
	119	{
	120	int size = 0;
	121	int ptr = 0;
	122
	123	/* Log a line for each signature */
	124
	125	uschar *logmsg = string_append(NULL, &size, &ptr, 5,
abe1010c	126	string_sprintf("d=%s s=%s c=%s/%s a=%s b=%d ",
1cfe5c1c JH	127	sig->domain,
	128	sig->selector,
	129	sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
	130	sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
abe1010c JH	131	sig->algo == PDKIM_ALGO_RSA_SHA256 ? "rsa-sha256" : "rsa-sha1",
	132	sig->sigdata_len * 8
	133	),
1cfe5c1c JH	134
	135	sig->identity ? string_sprintf("i=%s ", sig->identity) : US"",
	136	sig->created > 0 ? string_sprintf("t=%lu ", sig->created) : US"",
	137	sig->expires > 0 ? string_sprintf("x=%lu ", sig->expires) : US"",
	138	sig->bodylength > -1 ? string_sprintf("l=%lu ", sig->bodylength) : US""
	139	);
	140
	141	switch (sig->verify_status)
	142	{
	143	case PDKIM_VERIFY_NONE:
	144	logmsg = string_append(logmsg, &size, &ptr, 1, "[not verified]");
80a47a2c	145	break;
1cfe5c1c JH	146
	147	case PDKIM_VERIFY_INVALID:
	148	logmsg = string_append(logmsg, &size, &ptr, 1, "[invalid - ");
	149	switch (sig->verify_ext_status)
	150	{
	151	case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
	152	logmsg = string_append(logmsg, &size, &ptr, 1,
	153	"public key record (currently?) unavailable]");
	154	break;
	155
	156	case PDKIM_VERIFY_INVALID_BUFFER_SIZE:
	157	logmsg = string_append(logmsg, &size, &ptr, 1,
	158	"overlong public key record]");
	159	break;
	160
	161	case PDKIM_VERIFY_INVALID_PUBKEY_PARSING:
	162	logmsg = string_append(logmsg, &size, &ptr, 1,
	163	"syntax error in public key record]");
	164	break;
	165
	166	default:
	167	logmsg = string_append(logmsg, &size, &ptr, 1,
	168	"unspecified problem]");
	169	}
80a47a2c	170	break;
1cfe5c1c JH	171
	172	case PDKIM_VERIFY_FAIL:
	173	logmsg =
	174	string_append(logmsg, &size, &ptr, 1, "[verification failed - ");
	175	switch (sig->verify_ext_status)
	176	{
	177	case PDKIM_VERIFY_FAIL_BODY:
	178	logmsg = string_append(logmsg, &size, &ptr, 1,
	179	"body hash mismatch (body probably modified in transit)]");
	180	break;
	181
	182	case PDKIM_VERIFY_FAIL_MESSAGE:
	183	logmsg = string_append(logmsg, &size, &ptr, 1,
	184	"signature did not verify (headers probably modified in transit)]");
	185	break;
	186
	187	default:
	188	logmsg = string_append(logmsg, &size, &ptr, 1, "unspecified reason]");
	189	}
80a47a2c	190	break;
1cfe5c1c JH	191
	192	case PDKIM_VERIFY_PASS:
	193	logmsg =
	194	string_append(logmsg, &size, &ptr, 1, "[verification succeeded]");
80a47a2c TK	195	break;
	196	}
	197
1cfe5c1c JH	198	logmsg[ptr] = '\0';
1cfe5c1c JH	199	log_write(0, LOG_MAIN, "DKIM: %s", logmsg);
80a47a2c	200
1cfe5c1c JH	201	/* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */
	202
	203	dkim_signers = string_append(dkim_signers,
	204	&dkim_signers_size,
	205	&dkim_signers_ptr, 2, sig->domain, ":");
	206
	207	if (sig->identity)
9e5d6b55	208	dkim_signers = string_append(dkim_signers,
1cfe5c1c JH	209	&dkim_signers_size,
1cfe5c1c JH	210	&dkim_signers_ptr, 2, sig->identity, ":");
80a47a2c	211
1cfe5c1c	212	/* Process next signature */
80a47a2c TK	213	}
80a47a2c TK	214
1cfe5c1c JH	215	/* NULL-terminate and chop the last colon from the domain list */
	216
	217	if (dkim_signers)
	218	{
	219	dkim_signers[dkim_signers_ptr] = '\0';
	220	if (Ustrlen(dkim_signers) > 0)
	221	dkim_signers[Ustrlen(dkim_signers) - 1] = '\0';
0d2b278d	222	}
80a47a2c TK	223	}
	224
	225
1cfe5c1c JH	226	void
	227	dkim_exim_acl_setup(uschar * id)
	228	{
	229	pdkim_signature * sig;
	230	uschar * cmp_val;
	231
1cfe5c1c JH	232	dkim_cur_sig = NULL;
	233	dkim_cur_signer = id;
	234
	235	if (dkim_disable_verify \|\| !id \|\| !dkim_verify_ctx)
	236	return;
	237
	238	/* Find signature to run ACL on */
	239
	240	for (sig = dkim_signatures; sig; sig = sig->next)
	241	if ( (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain)
	242	&& strcmpic(cmp_val, id) == 0
	243	)
	244	{
	245	dkim_cur_sig = sig;
	246
	247	/* The "dkim_domain" and "dkim_selector" expansion variables have
	248	related globals, since they are used in the signing code too.
	249	Instead of inventing separate names for verification, we set
	250	them here. This is easy since a domain and selector is guaranteed
	251	to be in a signature. The other dkim_* expansion items are
	252	dynamically fetched from dkim_cur_sig at expansion time (see
	253	function below). */
	254
	255	dkim_signing_domain = US sig->domain;
	256	dkim_signing_selector = US sig->selector;
abe1010c	257	dkim_key_length = sig->sigdata_len * 8;
1cfe5c1c	258	return;
80a47a2c	259	}
80a47a2c TK	260	}
	261
	262
1cfe5c1c JH	263	static uschar *
	264	dkim_exim_expand_defaults(int what)
	265	{
	266	switch (what)
	267	{
	268	case DKIM_ALGO: return US"";
	269	case DKIM_BODYLENGTH: return US"9999999999999";
	270	case DKIM_CANON_BODY: return US"";
	271	case DKIM_CANON_HEADERS: return US"";
	272	case DKIM_COPIEDHEADERS: return US"";
	273	case DKIM_CREATED: return US"0";
	274	case DKIM_EXPIRES: return US"9999999999999";
	275	case DKIM_HEADERNAMES: return US"";
	276	case DKIM_IDENTITY: return US"";
	277	case DKIM_KEY_GRANULARITY: return US"*";
	278	case DKIM_KEY_SRVTYPE: return US"*";
	279	case DKIM_KEY_NOTES: return US"";
	280	case DKIM_KEY_TESTING: return US"0";
	281	case DKIM_NOSUBDOMAINS: return US"0";
	282	case DKIM_VERIFY_STATUS: return US"none";
	283	case DKIM_VERIFY_REASON: return US"";
	284	default: return US"";
	285	}
	286	}
80a47a2c	287
80a47a2c	288
1cfe5c1c JH	289	uschar *
	290	dkim_exim_expand_query(int what)
	291	{
	292	if (!dkim_verify_ctx \|\| dkim_disable_verify \|\| !dkim_cur_sig)
	293	return dkim_exim_expand_defaults(what);
	294
	295	switch (what)
	296	{
	297	case DKIM_ALGO:
	298	switch (dkim_cur_sig->algo)
	299	{
	300	case PDKIM_ALGO_RSA_SHA1: return US"rsa-sha1";
	301	case PDKIM_ALGO_RSA_SHA256:
	302	default: return US"rsa-sha256";
da5dfc3a	303	}
1cfe5c1c JH	304
	305	case DKIM_BODYLENGTH:
	306	return dkim_cur_sig->bodylength >= 0
	307	? string_sprintf(OFF_T_FMT, (LONGLONG_T) dkim_cur_sig->bodylength)
	308	: dkim_exim_expand_defaults(what);
	309
	310	case DKIM_CANON_BODY:
	311	switch (dkim_cur_sig->canon_body)
	312	{
	313	case PDKIM_CANON_RELAXED: return US"relaxed";
	314	case PDKIM_CANON_SIMPLE:
	315	default: return US"simple";
80a47a2c	316	}
1cfe5c1c JH	317
	318	case DKIM_CANON_HEADERS:
	319	switch (dkim_cur_sig->canon_headers)
	320	{
	321	case PDKIM_CANON_RELAXED: return US"relaxed";
	322	case PDKIM_CANON_SIMPLE:
	323	default: return US"simple";
	324	}
	325
	326	case DKIM_COPIEDHEADERS:
	327	return dkim_cur_sig->copiedheaders
	328	? US dkim_cur_sig->copiedheaders : dkim_exim_expand_defaults(what);
	329
	330	case DKIM_CREATED:
	331	return dkim_cur_sig->created > 0
	332	? string_sprintf("%llu", dkim_cur_sig->created)
	333	: dkim_exim_expand_defaults(what);
	334
	335	case DKIM_EXPIRES:
	336	return dkim_cur_sig->expires > 0
	337	? string_sprintf("%llu", dkim_cur_sig->expires)
	338	: dkim_exim_expand_defaults(what);
	339
	340	case DKIM_HEADERNAMES:
	341	return dkim_cur_sig->headernames
	342	? US dkim_cur_sig->headernames : dkim_exim_expand_defaults(what);
	343
	344	case DKIM_IDENTITY:
	345	return dkim_cur_sig->identity
	346	? US dkim_cur_sig->identity : dkim_exim_expand_defaults(what);
	347
	348	case DKIM_KEY_GRANULARITY:
	349	return dkim_cur_sig->pubkey
	350	? dkim_cur_sig->pubkey->granularity
	351	? US dkim_cur_sig->pubkey->granularity
	352	: dkim_exim_expand_defaults(what)
	353	: dkim_exim_expand_defaults(what);
	354
	355	case DKIM_KEY_SRVTYPE:
	356	return dkim_cur_sig->pubkey
	357	? dkim_cur_sig->pubkey->srvtype
	358	? US dkim_cur_sig->pubkey->srvtype
	359	: dkim_exim_expand_defaults(what)
	360	: dkim_exim_expand_defaults(what);
	361
	362	case DKIM_KEY_NOTES:
	363	return dkim_cur_sig->pubkey
	364	? dkim_cur_sig->pubkey->notes
	365	? US dkim_cur_sig->pubkey->notes
	366	: dkim_exim_expand_defaults(what)
	367	: dkim_exim_expand_defaults(what);
	368
	369	case DKIM_KEY_TESTING:
	370	return dkim_cur_sig->pubkey
	371	? dkim_cur_sig->pubkey->testing
	372	? US"1"
	373	: dkim_exim_expand_defaults(what)
	374	: dkim_exim_expand_defaults(what);
	375
	376	case DKIM_NOSUBDOMAINS:
	377	return dkim_cur_sig->pubkey
	378	? dkim_cur_sig->pubkey->no_subdomaining
	379	? US"1"
	380	: dkim_exim_expand_defaults(what)
381	: dkim_exim_expand_defaults(what);
382
383	case DKIM_VERIFY_STATUS:
384	switch (dkim_cur_sig->verify_status)
385	{
386	case PDKIM_VERIFY_INVALID: return US"invalid";
387	case PDKIM_VERIFY_FAIL: return US"fail";
388	case PDKIM_VERIFY_PASS: return US"pass";
389	case PDKIM_VERIFY_NONE:
390	default: return US"none";
80a47a2c	391	}
80a47a2c	392
1cfe5c1c JH	393	case DKIM_VERIFY_REASON:
	394	switch (dkim_cur_sig->verify_ext_status)
	395	{
	396	case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
	397	return US"pubkey_unavailable";
	398	case PDKIM_VERIFY_INVALID_PUBKEY_PARSING: return US"pubkey_syntax";
	399	case PDKIM_VERIFY_FAIL_BODY: return US"bodyhash_mismatch";
	400	case PDKIM_VERIFY_FAIL_MESSAGE: return US"signature_incorrect";
	401	}
80a47a2c	402
1cfe5c1c JH	403	default:
1cfe5c1c JH	404	return US"";
80a47a2c TK	405	}
	406	}
	407
	408
55414b25	409	uschar *
1cfe5c1c JH	410	dkim_exim_sign(int dkim_fd, uschar * dkim_private_key,
	411	const uschar * dkim_domain, uschar * dkim_selector,
	412	uschar * dkim_canon, uschar * dkim_sign_headers)
55414b25	413	{
1cfe5c1c JH	414	int sep = 0;
	415	uschar *seen_items = NULL;
	416	int seen_items_size = 0;
	417	int seen_items_offset = 0;
	418	uschar itembuf[256];
	419	uschar *dkim_canon_expanded;
	420	uschar *dkim_sign_headers_expanded;
	421	uschar *dkim_private_key_expanded;
	422	pdkim_ctx *ctx = NULL;
	423	uschar *rc = NULL;
	424	uschar *sigbuf = NULL;
	425	int sigsize = 0;
	426	int sigptr = 0;
	427	pdkim_signature *signature;
	428	int pdkim_canon;
	429	int pdkim_rc;
	430	int sread;
	431	char buf[4096];
	432	int save_errno = 0;
	433	int old_pool = store_pool;
	434
	435	store_pool = POOL_MAIN;
	436
	437	if (!(dkim_domain = expand_cstring(dkim_domain)))
	438	{
	439	/* expansion error, do not send message. */
	440	log_write(0, LOG_MAIN \| LOG_PANIC, "failed to expand "
	441	"dkim_domain: %s", expand_string_message);
	442	rc = NULL;
	443	goto CLEANUP;
	444	}
	445
	446	/* Set $dkim_domain expansion variable to each unique domain in list. */
	447
	448	while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep,
	449	itembuf, sizeof(itembuf))))
	450	{
	451	if (!dkim_signing_domain \|\| dkim_signing_domain[0] == '\0')
	452	continue;
	453
	454	/* Only sign once for each domain, no matter how often it
	455	appears in the expanded list. */
	456
	457	if (seen_items)
	458	{
	459	const uschar *seen_items_list = seen_items;
	460	if (match_isinlist(dkim_signing_domain,
	461	&seen_items_list, 0, NULL, NULL, MCL_STRING, TRUE,
	462	NULL) == OK)
	463	continue;
	464
	465	seen_items =
	466	string_append(seen_items, &seen_items_size, &seen_items_offset, 1, ":");
	467	}
	468
	469	seen_items =
	470	string_append(seen_items, &seen_items_size, &seen_items_offset, 1,
	471	dkim_signing_domain);
	472	seen_items[seen_items_offset] = '\0';
	473
	474	/* Set up $dkim_selector expansion variable. */
	475
	476	if (!(dkim_signing_selector = expand_string(dkim_selector)))
	477	{
478	log_write(0, LOG_MAIN \| LOG_PANIC, "failed to expand "
479	"dkim_selector: %s", expand_string_message);
480	rc = NULL;
481	goto CLEANUP;
482	}
483
484	/* Get canonicalization to use */
485
486	dkim_canon_expanded = dkim_canon ? expand_string(dkim_canon) : US"relaxed";
487	if (!dkim_canon_expanded)
488	{
80a47a2c	489	/* expansion error, do not send message. */
1cfe5c1c JH	490	log_write(0, LOG_MAIN \| LOG_PANIC, "failed to expand "
1cfe5c1c JH	491	"dkim_canon: %s", expand_string_message);
80a47a2c TK	492	rc = NULL;
80a47a2c TK	493	goto CLEANUP;
1cfe5c1c	494	}
80a47a2c	495
1cfe5c1c JH	496	if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0)
	497	pdkim_canon = PDKIM_CANON_RELAXED;
	498	else if (Ustrcmp(dkim_canon_expanded, "simple") == 0)
	499	pdkim_canon = PDKIM_CANON_SIMPLE;
	500	else
	501	{
	502	log_write(0, LOG_MAIN,
	503	"DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n",
	504	dkim_canon_expanded);
	505	pdkim_canon = PDKIM_CANON_RELAXED;
a8e1eeba	506	}
1cfe5c1c JH	507
	508	dkim_sign_headers_expanded = NULL;
	509	if (dkim_sign_headers)
	510	if (!(dkim_sign_headers_expanded = expand_string(dkim_sign_headers)))
	511	{
	512	log_write(0, LOG_MAIN \| LOG_PANIC, "failed to expand "
	513	"dkim_sign_headers: %s", expand_string_message);
a8e1eeba MH	514	rc = NULL;
a8e1eeba MH	515	goto CLEANUP;
1cfe5c1c JH	516	}
	517	/* else pass NULL, which means default header list */
	518
	519	/* Get private key to use. */
	520
	521	if (!(dkim_private_key_expanded = expand_string(dkim_private_key)))
	522	{
	523	log_write(0, LOG_MAIN \| LOG_PANIC, "failed to expand "
	524	"dkim_private_key: %s", expand_string_message);
	525	rc = NULL;
	526	goto CLEANUP;
a8e1eeba	527	}
80a47a2c	528
1cfe5c1c JH	529	if ( Ustrlen(dkim_private_key_expanded) == 0
	530	\|\| Ustrcmp(dkim_private_key_expanded, "0") == 0
	531	\|\| Ustrcmp(dkim_private_key_expanded, "false") == 0
	532	)
	533	continue; /* don't sign, but no error */
	534
	535	if (dkim_private_key_expanded[0] == '/')
	536	{
	537	int privkey_fd = 0;
	538
	539	/* Looks like a filename, load the private key. */
	540
	541	memset(big_buffer, 0, big_buffer_size);
	542	privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY);
	543	if (privkey_fd < 0)
	544	{
	545	log_write(0, LOG_MAIN \| LOG_PANIC, "unable to open "
	546	"private key file for reading: %s",
	547	dkim_private_key_expanded);
80a47a2c TK	548	rc = NULL;
80a47a2c TK	549	goto CLEANUP;
db4d0902	550	}
80a47a2c	551
1cfe5c1c JH	552	if (read(privkey_fd, big_buffer, big_buffer_size - 2) < 0)
	553	{
	554	log_write(0, LOG_MAIN\|LOG_PANIC, "unable to read private key file: %s",
	555	dkim_private_key_expanded);
cf745305 TK	556	rc = NULL;
cf745305 TK	557	goto CLEANUP;
1ac6b2e7	558	}
80a47a2c	559
1cfe5c1c JH	560	(void) close(privkey_fd);
1cfe5c1c JH	561	dkim_private_key_expanded = big_buffer;
a8e1eeba	562	}
1cfe5c1c	563
0d04a285	564	ctx = pdkim_init_sign( (char *) dkim_signing_domain,
1cfe5c1c JH	565	(char *) dkim_signing_selector,
1cfe5c1c JH	566	(char *) dkim_private_key_expanded);
1cfe5c1c JH	567	pdkim_set_optional(ctx,
	568	(char *) dkim_sign_headers_expanded,
	569	NULL,
	570	pdkim_canon,
	571	pdkim_canon, -1, PDKIM_ALGO_RSA_SHA256, 0, 0);
	572
	573	lseek(dkim_fd, 0, SEEK_SET);
	574
	575	while ((sread = read(dkim_fd, &buf, 4096)) > 0)
	576	if (pdkim_feed(ctx, buf, sread) != PDKIM_OK)
	577	{
80a47a2c TK	578	rc = NULL;
80a47a2c TK	579	goto CLEANUP;
1cfe5c1c JH	580	}
	581
	582	/* Handle failed read above. */
	583	if (sread == -1)
	584	{
	585	debug_printf("DKIM: Error reading -K file.\n");
	586	save_errno = errno;
	587	rc = NULL;
	588	goto CLEANUP;
80a47a2c	589	}
80a47a2c	590
1cfe5c1c JH	591	if ((pdkim_rc = pdkim_feed_finish(ctx, &signature)) != PDKIM_OK)
	592	{
	593	log_write(0, LOG_MAIN\|LOG_PANIC, "DKIM: signing failed (RC %d)", pdkim_rc);
	594	rc = NULL;
	595	goto CLEANUP;
a8e1eeba	596	}
80a47a2c	597
1cfe5c1c JH	598	sigbuf = string_append(sigbuf, &sigsize, &sigptr, 2,
1cfe5c1c JH	599	US signature->signature_header, US"\r\n");
80a47a2c	600
1cfe5c1c JH	601	pdkim_free_ctx(ctx);
1cfe5c1c JH	602	ctx = NULL;
80a47a2c	603	}
a8e1eeba	604
1cfe5c1c JH	605	if (sigbuf)
	606	{
	607	sigbuf[sigptr] = '\0';
	608	rc = sigbuf;
	609	}
	610	else
	611	rc = US"";
	612
	613	CLEANUP:
	614	if (ctx)
	615	pdkim_free_ctx(ctx);
	616	store_pool = old_pool;
	617	errno = save_errno;
	618	return rc;
93f2d376	619	}
80a47a2c TK	620
80a47a2c TK	621	#endif