* Exim - an Internet mail transport agent *
*************************************************/
-/* Copyright (c) University of Cambridge, 1995 - 2017 */
+/* Copyright (c) University of Cambridge, 1995 - 2018 */
/* See the file NOTICE for conditions of use and distribution. */
/* Code for DKIM support. Other DKIM relevant code is in
+pdkim_ctx dkim_sign_ctx;
int dkim_verify_oldpool;
pdkim_ctx *dkim_verify_ctx = NULL;
/*XXX the caller only uses the first record if we return multiple.
-Could we hand back an allocated string?
*/
-static int
-dkim_exim_query_dns_txt(char *name, char *answer)
+uschar *
+dkim_exim_query_dns_txt(uschar * name)
{
dns_answer dnsa;
dns_scan dnss;
dns_record *rr;
+gstring * g = NULL;
lookup_dnssec_authenticated = NULL;
-if (dns_lookup(&dnsa, US name, T_TXT, NULL) != DNS_SUCCEED)
- return PDKIM_FAIL; /*XXX better error detail? logging? */
+if (dns_lookup(&dnsa, name, T_TXT, NULL) != DNS_SUCCEED)
+ return NULL; /*XXX better error detail? logging? */
/* Search for TXT record */
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, CS (rr->data + rr_offset));
+
+ g = string_catn(g, US(rr->data + rr_offset), len);
+ if (g->ptr >= PDKIM_DNS_TXT_MAX_RECLEN)
+ goto bad;
+
rr_offset += len;
- answer_offset += len;
- if (answer_offset >= PDKIM_DNS_TXT_MAX_RECLEN)
- return PDKIM_FAIL; /*XXX better error detail? logging? */
}
- return PDKIM_OK;
+
+ /* check if this looks like a DKIM record */
+ if (Ustrncmp(g->s, "v=", 2) != 0 || strncasecmp(CS g->s, "v=dkim", 6) == 0)
+ {
+ gstring_reset_unused(g);
+ return string_from_gstring(g);
+ }
+
+ if (g) g->ptr = 0; /* overwrite previous record */
}
-return PDKIM_FAIL; /*XXX better error detail? logging? */
+bad:
+if (g) store_reset(g);
+return NULL; /*XXX better error detail? logging? */
}
static void
dkim_exim_verify_log_sig(pdkim_signature * sig)
{
-gstring * logmsg = string_catn(NULL, "DKIM: ", 6);
+gstring * logmsg;
uschar * s;
+if (!sig) return;
+
+/* Remember the domain for the first pass result */
+
+if ( !dkim_verify_overall
+ && dkim_verify_status
+ ? Ustrcmp(dkim_verify_status, US"pass") == 0
+ : sig->verify_status == PDKIM_VERIFY_PASS
+ )
+ dkim_verify_overall = string_copy(sig->domain);
+
+/* Rewrite the sig result if the ACL overrode it. This is only
+needed because the DMARC code (sigh) peeks at the dkim sigs.
+Mark the sig for this having been done. */
+
+if ( dkim_verify_status
+ && ( dkim_verify_status != dkim_exim_expand_query(DKIM_VERIFY_STATUS)
+ || dkim_verify_reason != dkim_exim_expand_query(DKIM_VERIFY_REASON)
+ ) )
+ { /* overridden by ACL */
+ sig->verify_ext_status = -1;
+ if (Ustrcmp(dkim_verify_status, US"fail") == 0)
+ sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_FAIL;
+ else if (Ustrcmp(dkim_verify_status, US"invalid") == 0)
+ sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_INVALID;
+ else if (Ustrcmp(dkim_verify_status, US"none") == 0)
+ sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_NONE;
+ else if (Ustrcmp(dkim_verify_status, US"pass") == 0)
+ sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_PASS;
+ else
+ sig->verify_status = -1;
+ }
+
+if (!LOGGING(dkim_verbose)) return;
+
+
+logmsg = string_catn(NULL, US"DKIM: ", 6);
if (!(s = sig->domain)) s = US"<UNSET>";
logmsg = string_append(logmsg, 2, "d=", s);
if (!(s = sig->selector)) s = US"<UNSET>";
logmsg = string_append(logmsg, 2, " s=", s);
-logmsg = string_append(logmsg, 7,
-" c=", sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
-"/", sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
-" a=", dkim_sig_to_a_tag(sig),
+logmsg = string_append(logmsg, 7,
+ " c=", sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
+ "/", sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
+ " a=", dkim_sig_to_a_tag(sig),
string_sprintf(" b=" SIZE_T_FMT,
(int)sig->sighash.len > -1 ? sig->sighash.len * 8 : 0));
if ((s= sig->identity)) logmsg = string_append(logmsg, 2, " i=", s);
if (sig->bodylength > -1) logmsg = string_cat(logmsg,
string_sprintf(" l=%lu", sig->bodylength));
-if ( !dkim_verify_status
- || ( dkim_verify_status == dkim_exim_expand_query(DKIM_VERIFY_STATUS)
- && dkim_verify_reason == dkim_exim_expand_query(DKIM_VERIFY_REASON)
- ) )
+if (sig->verify_status & PDKIM_VERIFY_POLICY)
+ logmsg = string_append(logmsg, 5,
+ US" [", dkim_verify_status, US" - ", dkim_verify_reason, US"]");
+else
switch (sig->verify_status)
{
case PDKIM_VERIFY_NONE:
- logmsg = string_cat(logmsg, " [not verified]");
+ logmsg = string_cat(logmsg, US" [not verified]");
break;
case PDKIM_VERIFY_INVALID:
- logmsg = string_cat(logmsg, " [invalid - ");
+ logmsg = string_cat(logmsg, US" [invalid - ");
switch (sig->verify_ext_status)
{
case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
logmsg = string_cat(logmsg,
- "public key record (currently?) unavailable]");
+ US"public key record (currently?) unavailable]");
break;
case PDKIM_VERIFY_INVALID_BUFFER_SIZE:
- logmsg = string_cat(logmsg, "overlong public key record]");
+ logmsg = string_cat(logmsg, US"overlong public key record]");
break;
case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:
case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT:
- logmsg = string_cat(logmsg, "syntax error in public key record]");
+ logmsg = string_cat(logmsg, US"syntax error in public key record]");
break;
case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR:
- logmsg = string_cat(logmsg, "signature tag missing or invalid]");
+ logmsg = string_cat(logmsg, US"signature tag missing or invalid]");
break;
case PDKIM_VERIFY_INVALID_DKIM_VERSION:
- logmsg = string_cat(logmsg, "unsupported DKIM version]");
+ logmsg = string_cat(logmsg, US"unsupported DKIM version]");
break;
default:
- logmsg = string_cat(logmsg, "unspecified problem]");
+ logmsg = string_cat(logmsg, US"unspecified problem]");
}
break;
case PDKIM_VERIFY_FAIL:
- logmsg = string_cat(logmsg, " [verification failed - ");
+ logmsg = string_cat(logmsg, US" [verification failed - ");
switch (sig->verify_ext_status)
{
case PDKIM_VERIFY_FAIL_BODY:
logmsg = string_cat(logmsg,
- "body hash mismatch (body probably modified in transit)]");
+ US"body hash mismatch (body probably modified in transit)]");
break;
case PDKIM_VERIFY_FAIL_MESSAGE:
logmsg = string_cat(logmsg,
- "signature did not verify (headers probably modified in transit)]");
- break;
+ US"signature did not verify "
+ "(headers probably modified in transit)]");
+ break;
default:
- logmsg = string_cat(logmsg, "unspecified reason]");
+ logmsg = string_cat(logmsg, US"unspecified reason]");
}
break;
case PDKIM_VERIFY_PASS:
- logmsg = string_cat(logmsg, " [verification succeeded]");
+ logmsg = string_cat(logmsg, US" [verification succeeded]");
break;
}
-else
- logmsg = string_append(logmsg, 5,
- US" [", dkim_verify_status, US" - ", dkim_verify_reason, US"]");
-log_write(0, LOG_MAIN, string_from_gstring(logmsg));
+log_write(0, LOG_MAIN, "%s", string_from_gstring(logmsg));
return;
}
-/* Log a line for "the current" signature */
-void
-dkim_exim_verify_log_item(void)
-{
-dkim_exim_verify_log_sig(dkim_cur_sig);
-}
-
-
/* Log a line for each signature */
void
dkim_exim_verify_log_all(void)
pdkim_signature * sig;
int rc;
gstring * g = NULL;
-const uschar * errstr;
+const uschar * errstr = NULL;
store_pool = POOL_PERM;
/* Finish DKIM operation and fetch link to signatures chain */
rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures, &errstr);
-if (rc != PDKIM_OK)
- {
- log_write(0, LOG_MAIN, "DKIM: validation error: %.100s%s%s", pdkim_errstr(rc),
- errstr ? ": " : "", errstr ? errstr : US"");
- goto out;
- }
+if (rc != PDKIM_OK && errstr)
+ log_write(0, LOG_MAIN, "DKIM: validation error: %s", errstr);
/* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */
}
-void
-dkim_exim_acl_setup(uschar * id)
+
+/* Args as per dkim_exim_acl_run() below */
+static int
+dkim_acl_call(uschar * id, gstring ** res_ptr,
+ uschar ** user_msgptr, uschar ** log_msgptr)
+{
+int rc;
+DEBUG(D_receive)
+ debug_printf("calling acl_smtp_dkim for dkim_cur_signer='%s'\n", id);
+
+rc = acl_check(ACL_WHERE_DKIM, NULL, acl_smtp_dkim, user_msgptr, log_msgptr);
+dkim_exim_verify_log_sig(dkim_cur_sig);
+*res_ptr = string_append_listele(*res_ptr, ':', dkim_verify_status);
+return rc;
+}
+
+
+
+/* For the given identity, run the DKIM ACL once for each matching signature.
+
+Arguments
+ id Identity to look for in dkim signatures
+ res_ptr ptr to growable string-list of status results,
+ appended to per ACL run
+ 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
+dkim_exim_acl_run(uschar * id, gstring ** res_ptr,
+ uschar ** user_msgptr, uschar ** log_msgptr)
{
pdkim_signature * sig;
uschar * cmp_val;
+int rc = -1;
-dkim_cur_sig = NULL;
+dkim_verify_status = US"none";
+dkim_verify_reason = US"";
dkim_cur_signer = id;
if (dkim_disable_verify || !id || !dkim_verify_ctx)
- return;
+ return OK;
-/* Find signature to run ACL on */
+/* Find signatures 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). */
+ 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_cur_sig = sig;
dkim_signing_domain = US sig->domain;
dkim_signing_selector = US sig->selector;
dkim_key_length = sig->sighash.len * 8;
dkim_verify_status = dkim_exim_expand_query(DKIM_VERIFY_STATUS);
dkim_verify_reason = dkim_exim_expand_query(DKIM_VERIFY_REASON);
- return;
+
+ if ((rc = dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr)) != OK)
+ return rc;
}
+
+if (rc != -1)
+ return rc;
+
+/* No matching sig found. Call ACL once anyway. */
+
+dkim_cur_sig = NULL;
+return dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr);
}
}
-/* Generate signatures for the given file, returning a string.
+void
+dkim_exim_sign_init(void)
+{
+int old_pool = store_pool;
+store_pool = POOL_MAIN;
+pdkim_init_context(&dkim_sign_ctx, FALSE, &dkim_exim_query_dns_txt);
+store_pool = old_pool;
+}
+
+
+/* Generate signatures for the given file.
If a prefix is given, prepend it to the file for the calculations.
+
+Return:
+ NULL: error; error string written
+ string: signature header(s), or a zero-length string (not an error)
*/
gstring *
dkim_exim_sign(int fd, off_t off, uschar * prefix,
struct ob_dkim * dkim, const uschar ** errstr)
{
-const uschar * dkim_domain;
+const uschar * dkim_domain = NULL;
int sep = 0;
gstring * seen_doms = NULL;
-pdkim_ctx ctx;
pdkim_signature * sig;
gstring * sigbuf;
int pdkim_rc;
int save_errno = 0;
int old_pool = store_pool;
uschar * errwhen;
+const uschar * s;
-store_pool = POOL_MAIN;
+if (dkim->dot_stuffed)
+ dkim_sign_ctx.flags |= PDKIM_DOT_TERM;
-pdkim_init_context(&ctx, dkim->dot_stuffed, &dkim_exim_query_dns_txt);
+store_pool = POOL_MAIN;
-if (!(dkim_domain = expand_cstring(dkim->dkim_domain)))
+if ((s = dkim->dkim_domain) && !(dkim_domain = expand_cstring(s)))
/* expansion error, do not send message. */
{ errwhen = US"dkim_domain"; goto expand_bad; }
/* Set $dkim_domain expansion variable to each unique domain in list. */
-while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0)))
+if (dkim_domain)
+ while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0)))
{
const uschar * dkim_sel;
int sel_sep = 0;
)
continue; /* don't sign, but no error */
- if (dkim_private_key_expanded[0] == '/')
- {
- int privkey_fd, off = 0, len;
-
- /* Looks like a filename, load the private key. */
-
- memset(big_buffer, 0, big_buffer_size);
-
- if ((privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY)) < 0)
- {
- log_write(0, LOG_MAIN | LOG_PANIC, "unable to open "
- "private key file for reading: %s",
- dkim_private_key_expanded);
- goto bad;
- }
-
- do
- {
- if ((len = read(privkey_fd, big_buffer + off, big_buffer_size - 2 - off)) < 0)
- {
- (void) close(privkey_fd);
- log_write(0, LOG_MAIN|LOG_PANIC, "unable to read private key file: %s",
- dkim_private_key_expanded);
- goto bad;
- }
- off += len;
- }
- while (len > 0);
-
- (void) close(privkey_fd);
- big_buffer[off] = '\0';
- dkim_private_key_expanded = big_buffer;
- }
+ if ( dkim_private_key_expanded[0] == '/'
+ && !(dkim_private_key_expanded =
+ expand_file_big_buffer(dkim_private_key_expanded)))
+ goto bad;
if (!(dkim_hash_expanded = expand_string(dkim->dkim_hash)))
{ errwhen = US"dkim_hash"; goto expand_bad; }
else if (!*dkim_identity_expanded)
dkim_identity_expanded = NULL;
- /*XXX so we currently nail signing to RSA + this hash.
- Need to extract algo from privkey and check for disallowed combos. */
-
- if (!(sig = pdkim_init_sign(&ctx, dkim_signing_domain,
+ if (!(sig = pdkim_init_sign(&dkim_sign_ctx, dkim_signing_domain,
dkim_signing_selector,
dkim_private_key_expanded,
dkim_hash_expanded,
pdkim_set_optional(sig,
CS dkim_sign_headers_expanded,
- dkim_identity_expanded,
+ CS dkim_identity_expanded,
pdkim_canon,
pdkim_canon, -1, 0, 0);
- if (!ctx.sig) /* link sig to context chain */
- ctx.sig = sig;
+ if (!pdkim_set_sig_bodyhash(&dkim_sign_ctx, sig))
+ goto bad;
+
+ if (!dkim_sign_ctx.sig) /* link sig to context chain */
+ dkim_sign_ctx.sig = sig;
else
{
- pdkim_signature * n = ctx.sig;
+ pdkim_signature * n = dkim_sign_ctx.sig;
while (n->next) n = n->next;
n->next = sig;
}
}
}
-if (prefix)
- pdkim_feed(&ctx, prefix, Ustrlen(prefix));
+/* We may need to carry on with the data-feed even if there are no DKIM sigs to
+produce, if some other package (eg. ARC) is signing. */
-if (lseek(fd, off, SEEK_SET) < 0)
- sread = -1;
-else
- while ((sread = read(fd, &buf, sizeof(buf))) > 0)
- if ((pdkim_rc = pdkim_feed(&ctx, buf, sread)) != PDKIM_OK)
- goto pk_bad;
-
-/* Handle failed read above. */
-if (sread == -1)
+if (!dkim_sign_ctx.sig && !dkim->force_bodyhash)
{
- debug_printf("DKIM: Error reading -K file.\n");
- save_errno = errno;
- goto bad;
+ DEBUG(D_transport) debug_printf("DKIM: no viable signatures to use\n");
+ sigbuf = string_get(1); /* return a zero-len string */
}
+else
+ {
+ if (prefix && (pdkim_rc = pdkim_feed(&dkim_sign_ctx, prefix, Ustrlen(prefix))) != PDKIM_OK)
+ goto pk_bad;
+
+ if (lseek(fd, off, SEEK_SET) < 0)
+ sread = -1;
+ else
+ while ((sread = read(fd, &buf, sizeof(buf))) > 0)
+ if ((pdkim_rc = pdkim_feed(&dkim_sign_ctx, buf, sread)) != PDKIM_OK)
+ goto pk_bad;
+
+ /* Handle failed read above. */
+ if (sread == -1)
+ {
+ debug_printf("DKIM: Error reading -K file.\n");
+ save_errno = errno;
+ goto bad;
+ }
-/* Build string of headers, one per signature */
-
-if ((pdkim_rc = pdkim_feed_finish(&ctx, &sig, errstr)) != PDKIM_OK)
- goto pk_bad;
+ /* Build string of headers, one per signature */
-for (sigbuf = NULL; sig; sig = sig->next)
- sigbuf = string_append(sigbuf, 2, US sig->signature_header, US"\r\n");
+ if ((pdkim_rc = pdkim_feed_finish(&dkim_sign_ctx, &sig, errstr)) != PDKIM_OK)
+ goto pk_bad;
-(void) string_from_gstring(sigbuf);
+ if (!sig)
+ {
+ DEBUG(D_transport) debug_printf("DKIM: no signatures to use\n");
+ sigbuf = string_get(1); /* return a zero-len string */
+ }
+ else for (sigbuf = NULL; sig; sig = sig->next)
+ sigbuf = string_append(sigbuf, 2, US sig->signature_header, US"\r\n");
+ }
CLEANUP:
+ (void) string_from_gstring(sigbuf);
store_pool = old_pool;
errno = save_errno;
return sigbuf;
goto bad;
}
+
+
+
+gstring *
+authres_dkim(gstring * g)
+{
+pdkim_signature * sig;
+int start = 0; /* compiler quietening */
+
+DEBUG(D_acl) start = g->ptr;
+
+for (sig = dkim_signatures; sig; sig = sig->next)
+ {
+ g = string_catn(g, US";\n\tdkim=", 8);
+
+ if (sig->verify_status & PDKIM_VERIFY_POLICY)
+ g = string_append(g, 5,
+ US"policy (", dkim_verify_status, US" - ", dkim_verify_reason, US")");
+ else switch(sig->verify_status)
+ {
+ case PDKIM_VERIFY_NONE: g = string_cat(g, US"none"); break;
+ case PDKIM_VERIFY_INVALID:
+ switch (sig->verify_ext_status)
+ {
+ case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
+ g = string_cat(g, US"tmperror (pubkey unavailable)\n\t\t"); break;
+ case PDKIM_VERIFY_INVALID_BUFFER_SIZE:
+ g = string_cat(g, US"permerror (overlong public key record)\n\t\t"); break;
+ case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:
+ case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT:
+ g = string_cat(g, US"neutral (syntax error in public key record)\n\t\t");
+ break;
+ case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR:
+ g = string_cat(g, US"neutral (signature tag missing or invalid)\n\t\t");
+ break;
+ case PDKIM_VERIFY_INVALID_DKIM_VERSION:
+ g = string_cat(g, US"neutral (unsupported DKIM version)\n\t\t");
+ break;
+ default:
+ g = string_cat(g, US"permerror (unspecified problem)\n\t\t"); break;
+ }
+ break;
+ case PDKIM_VERIFY_FAIL:
+ switch (sig->verify_ext_status)
+ {
+ case PDKIM_VERIFY_FAIL_BODY:
+ g = string_cat(g,
+ US"fail (body hash mismatch; body probably modified in transit)\n\t\t");
+ break;
+ case PDKIM_VERIFY_FAIL_MESSAGE:
+ g = string_cat(g,
+ US"fail (signature did not verify; headers probably modified in transit)\n\t\t");
+ break;
+ default:
+ g = string_cat(g, US"fail (unspecified reason)\n\t\t");
+ break;
+ }
+ break;
+ case PDKIM_VERIFY_PASS: g = string_cat(g, US"pass"); break;
+ default: g = string_cat(g, US"permerror"); break;
+ }
+ if (sig->domain) g = string_append(g, 2, US" header.d=", sig->domain);
+ if (sig->identity) g = string_append(g, 2, US" header.i=", sig->identity);
+ if (sig->selector) g = string_append(g, 2, US" header.s=", sig->selector);
+ g = string_append(g, 2, US" header.a=", dkim_sig_to_a_tag(sig));
+ }
+
+DEBUG(D_acl)
+ if (g->ptr == start)
+ debug_printf("DKIM: no authres\n");
+ else
+ debug_printf("DKIM: authres '%.*s'\n", g->ptr - start - 3, g->s + start + 3);
+return g;
+}
+
+
# endif /*!MACRO_PREDEF*/
#endif /*!DISABLE_DKIM*/
projects / exim.git / blobdiff