*************************************************/
/* Copyright (c) University of Cambridge, 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
/* See the file NOTICE for conditions of use and distribution. */
/* Code for DKIM support. Other DKIM relevant code is in
params_dkim(void)
{
builtin_macro_create_var(US"_DKIM_SIGN_HEADERS", US PDKIM_DEFAULT_SIGN_HEADERS);
+builtin_macro_create_var(US"_DKIM_OVERSIGN_HEADERS", US PDKIM_OVERSIGN_HEADERS);
}
# else /*!MACRO_PREDEF*/
+pdkim_ctx dkim_sign_ctx;
int dkim_verify_oldpool;
pdkim_ctx *dkim_verify_ctx = NULL;
-pdkim_signature *dkim_signatures = NULL;
pdkim_signature *dkim_cur_sig = NULL;
static const uschar * dkim_collect_error = NULL;
+#define DKIM_MAX_SIGNATURES 20
-/*XXX the caller only uses the first record if we return multiple.
+
+/* Look up the DKIM record in DNS for the given hostname.
+Will use the first found if there are multiple.
+The return string is tainted, having come from off-site.
*/
-static uschar *
-dkim_exim_query_dns_txt(char * name)
+uschar *
+dkim_exim_query_dns_txt(const uschar * name)
{
-dns_answer dnsa;
+dns_answer * dnsa = store_get_dns_answer();
dns_scan dnss;
-dns_record *rr;
-gstring * g = NULL;
+rmark reset_point = store_mark();
+gstring * g = string_get_tainted(256, TRUE);
lookup_dnssec_authenticated = NULL;
-if (dns_lookup(&dnsa, US name, T_TXT, NULL) != DNS_SUCCEED)
+if (dns_lookup(dnsa, name, T_TXT, NULL) != DNS_SUCCEED)
+ {
+ store_free_dns_answer(dnsa);
return NULL; /*XXX better error detail? logging? */
+ }
/* Search for TXT record */
-for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
+for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
rr;
- rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
+ rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
if (rr->type == T_TXT)
{
int rr_offset = 0;
/* check if this looks like a DKIM record */
if (Ustrncmp(g->s, "v=", 2) != 0 || strncasecmp(CS g->s, "v=dkim", 6) == 0)
{
- store_reset(g->s + g->ptr + 1);
+ store_free_dns_answer(dnsa);
+ gstring_release_unused(g);
return string_from_gstring(g);
}
}
bad:
-if (g) store_reset(g);
+store_reset(reset_point);
+store_free_dns_answer(dnsa);
return NULL; /*XXX better error detail? logging? */
}
void
dkim_exim_init(void)
{
+if (f.dkim_init_done) return;
+f.dkim_init_done = TRUE;
pdkim_init();
}
void
dkim_exim_verify_init(BOOL dot_stuffing)
{
-/* There is a store-reset between header & body reception
-so cannot use the main pool. Any allocs done by Exim
-memory-handling must use the perm pool. */
+dkim_exim_init();
+
+/* There is a store-reset between header & body reception for the main pool
+(actually, after every header line) so cannot use that as we need the data we
+store per-header, during header processing, at the end of body reception
+for evaluating the signature. Any allocs done for dkim verify
+memory-handling must use a different pool. We use a separate one that we
+can reset per message. */
dkim_verify_oldpool = store_pool;
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
/* Free previous context if there is one */
/* Create new context */
dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt, dot_stuffing);
-dkim_collect_input = !!dkim_verify_ctx;
+dkim_collect_input = dkim_verify_ctx ? DKIM_MAX_SIGNATURES : 0;
dkim_collect_error = NULL;
/* Start feed up with any cached data */
{
int rc;
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
if ( dkim_collect_input
&& (rc = pdkim_feed(dkim_verify_ctx, data, len)) != PDKIM_OK)
{
dkim_collect_error = pdkim_errstr(rc);
log_write(0, LOG_MAIN,
"DKIM: validation error: %.100s", dkim_collect_error);
- dkim_collect_input = FALSE;
+ dkim_collect_input = 0;
}
store_pool = dkim_verify_oldpool;
}
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),
-string_sprintf(" b=" SIZE_T_FMT,
- (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : 0));
+logmsg = string_fmt_append(logmsg, " c=%s/%s a=%s b=" SIZE_T_FMT,
+ sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
+ sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed",
+ dkim_sig_to_a_tag(sig),
+ (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : (size_t)0);
if ((s= sig->identity)) logmsg = string_append(logmsg, 2, " i=", s);
-if (sig->created > 0) logmsg = string_cat(logmsg,
- string_sprintf(" t=%lu", sig->created));
-if (sig->expires > 0) logmsg = string_cat(logmsg,
- string_sprintf(" x=%lu", sig->expires));
-if (sig->bodylength > -1) logmsg = string_cat(logmsg,
- string_sprintf(" l=%lu", sig->bodylength));
+if (sig->created > 0) logmsg = string_fmt_append(logmsg, " t=%lu",
+ sig->created);
+if (sig->expires > 0) logmsg = string_fmt_append(logmsg, " x=%lu",
+ sig->expires);
+if (sig->bodylength > -1) logmsg = string_fmt_append(logmsg, " l=%lu",
+ sig->bodylength);
if (sig->verify_status & PDKIM_VERIFY_POLICY)
logmsg = string_append(logmsg, 5,
"(headers probably modified in transit)]");
break;
+ case PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE:
+ logmsg = string_cat(logmsg,
+ US"signature invalid (key too short)]");
+ break;
+
default:
logmsg = string_cat(logmsg, US"unspecified reason]");
}
void
dkim_exim_verify_log_all(void)
{
-pdkim_signature * sig;
-for (sig = dkim_signatures; sig; sig = sig->next) dkim_exim_verify_log_sig(sig);
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
+ dkim_exim_verify_log_sig(sig);
}
void
dkim_exim_verify_finish(void)
{
-pdkim_signature * sig;
int rc;
gstring * g = NULL;
const uschar * errstr = NULL;
-store_pool = POOL_PERM;
+store_pool = POOL_MESSAGE;
/* Delete eventual previous signature chain */
log_write(0, LOG_MAIN,
"DKIM: Error during validation, disabling signature verification: %.100s",
dkim_collect_error);
- dkim_disable_verify = TRUE;
+ f.dkim_disable_verify = TRUE;
goto out;
}
-dkim_collect_input = FALSE;
+dkim_collect_input = 0;
/* Finish DKIM operation and fetch link to signatures chain */
-rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures, &errstr);
+rc = pdkim_feed_finish(dkim_verify_ctx, (pdkim_signature **)&dkim_signatures,
+ &errstr);
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 */
-for (sig = dkim_signatures; sig; sig = sig->next)
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
{
if (sig->domain) g = string_append_listele(g, ':', sig->domain);
if (sig->identity) g = string_append_listele(g, ':', sig->identity);
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_verify_reason = US"";
dkim_cur_signer = id;
-if (dkim_disable_verify || !id || !dkim_verify_ctx)
+if (f.dkim_disable_verify || !id || !dkim_verify_ctx)
return OK;
/* Find signatures to run ACL on */
-for (sig = dkim_signatures; sig; sig = sig->next)
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
if ( (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain)
&& strcmpic(cmp_val, id) == 0
)
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_exim_expand_query() 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_key_length = sig->keybits;
/* These two return static strings, so we can compare the addr
later to see if the ACL overwrote them. Check that when logging */
uschar *
dkim_exim_expand_query(int what)
{
-if (!dkim_verify_ctx || dkim_disable_verify || !dkim_cur_sig)
+if (!dkim_verify_ctx || f.dkim_disable_verify || !dkim_cur_sig)
return dkim_exim_expand_defaults(what);
switch (what)
return US"pubkey_unavailable";
case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:return US"pubkey_dns_syntax";
case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return US"pubkey_der_syntax";
+ case PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE: return US"pubkey_too_short";
case PDKIM_VERIFY_FAIL_BODY: return US"bodyhash_mismatch";
case PDKIM_VERIFY_FAIL_MESSAGE: return US"signature_incorrect";
}
}
+void
+dkim_exim_sign_init(void)
+{
+int old_pool = store_pool;
+
+dkim_exim_init();
+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.
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;
/* Only sign once for each domain, no matter how often it
appears in the expanded list. */
+ dkim_signing_domain = string_copylc(dkim_signing_domain);
if (match_isinlist(dkim_signing_domain, CUSS &seen_doms,
0, NULL, NULL, MCL_STRING, TRUE, NULL) == OK)
continue;
for this domain. */
if (!(dkim_sel = expand_string(dkim->dkim_selector)))
- if (!(dkim_signing_selector = expand_string(dkim->dkim_selector)))
{ errwhen = US"dkim_selector"; goto expand_bad; }
while ((dkim_signing_selector = string_nextinlist(&dkim_sel, &sel_sep,
uschar * dkim_private_key_expanded;
uschar * dkim_hash_expanded;
uschar * dkim_identity_expanded = NULL;
+ uschar * dkim_timestamps_expanded = NULL;
+ unsigned long tval = 0, xval = 0;
/* Get canonicalization to use */
)
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;
- if (!(sig = pdkim_init_sign(&ctx, dkim_signing_domain,
+ if (dkim->dkim_timestamps)
+ if (!(dkim_timestamps_expanded = expand_string(dkim->dkim_timestamps)))
+ { errwhen = US"dkim_timestamps"; goto expand_bad; }
+ else
+ xval = (tval = (unsigned long) time(NULL))
+ + strtoul(CCS dkim_timestamps_expanded, NULL, 10);
+
+ if (!(sig = pdkim_init_sign(&dkim_sign_ctx, dkim_signing_domain,
dkim_signing_selector,
dkim_private_key_expanded,
dkim_hash_expanded,
CS dkim_sign_headers_expanded,
CS dkim_identity_expanded,
pdkim_canon,
- pdkim_canon, -1, 0, 0);
+ pdkim_canon, -1, tval, xval);
- if (!pdkim_set_bodyhash(&ctx, sig))
+ if (!pdkim_set_sig_bodyhash(&dkim_sign_ctx, sig))
goto bad;
- if (!ctx.sig) /* link sig to context chain */
- ctx.sig = sig;
+ 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 (!ctx.sig)
+
+/* 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 (!dkim_sign_ctx.sig && !dkim->force_bodyhash)
{
DEBUG(D_transport) debug_printf("DKIM: no viable signatures to use\n");
sigbuf = string_get(1); /* return a zero-len string */
- goto CLEANUP;
}
-
-if (prefix && (pdkim_rc = pdkim_feed(&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(&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;
- }
+ if (prefix && (pdkim_rc = pdkim_feed(&dkim_sign_ctx, prefix, Ustrlen(prefix))) != PDKIM_OK)
+ goto pk_bad;
-/* Build string of headers, one per signature */
+ 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;
-if ((pdkim_rc = pdkim_feed_finish(&ctx, &sig, errstr)) != 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;
+ }
-for (sigbuf = NULL; sig; sig = sig->next)
- sigbuf = string_append(sigbuf, 2, US sig->signature_header, US"\r\n");
+ /* Build string of headers, one per signature */
+
+ if ((pdkim_rc = pdkim_feed_finish(&dkim_sign_ctx, &sig, errstr)) != PDKIM_OK)
+ goto pk_bad;
+
+ 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);
pk_bad:
log_write(0, LOG_MAIN|LOG_PANIC,
- "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc));
+ "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc));
bad:
sigbuf = NULL;
goto CLEANUP;
expand_bad:
- log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand %s: %s",
- errwhen, expand_string_message);
+ *errstr = string_sprintf("failed to expand %s: %s",
+ errwhen, expand_string_message);
+ log_write(0, LOG_MAIN | LOG_PANIC, "%s", *errstr);
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)
+for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next)
{
g = string_catn(g, US";\n\tdkim=", 8);
switch (sig->verify_ext_status)
{
case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE:
- g = string_cat(g, US"tmperror (pubkey unavailable)"); break;
+ 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)"); break;
+ 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)");
+ g = string_cat(g, US"neutral (public key record import problem)\n\t\t");
break;
case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR:
- g = string_cat(g, US"neutral (signature tag missing or invalid)");
+ 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)");
+ g = string_cat(g, US"neutral (unsupported DKIM version)\n\t\t");
break;
default:
- g = string_cat(g, US"permerror (unspecified problem)"); break;
+ g = string_cat(g, US"permerror (unspecified problem)\n\t\t"); break;
}
break;
case PDKIM_VERIFY_FAIL:
{
case PDKIM_VERIFY_FAIL_BODY:
g = string_cat(g,
- US"fail (body hash mismatch; body probably modified in transit)");
+ 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)");
+ US"fail (signature did not verify; headers probably modified in transit)\n\t\t");
break;
+ case PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE: /* should this really be "polcy"? */
+ g = string_fmt_append(g, "fail (public key too short: %u bits)\n\t\t", sig->keybits);
+ break;
default:
- g = string_cat(g, US"fail (unspecified reason)");
+ g = string_cat(g, US"fail (unspecified reason)\n\t\t");
break;
}
break;
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;
}
git://git.exim.org / exim.git / blobdiff