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Add -dane_ee_no_namechecks s_client(1) option

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The DANE API supports a DANE_FLAG_NO_DANE_EE_NAMECHECKS option, but
there was no way to exercise/enable it via s_client.  This commit
addresses that gap.

Reviewed-by: Rich Salz <rsalz@openssl.org>
This commit is contained in:
Viktor Dukhovni 2016-08-19 11:59:47 -04:00
parent dc047d31fa
commit c4fbed6c31
2 changed files with 28 additions and 1 deletions
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10
apps/s_client.c
View file

@ -555,7 +555,7 @@ typedef enum OPTION_choice {
#ifndef OPENSSL_NO_CT
OPT_CT, OPT_NOCT, OPT_CTLOG_FILE,
#endif
OPT_DANE_TLSA_RRDATA
OPT_DANE_TLSA_RRDATA, OPT_DANE_EE_NO_NAME,
} OPTION_CHOICE;
OPTIONS s_client_options[] = {
@ -589,6 +589,8 @@ OPTIONS s_client_options[] = {
{"dane_tlsa_domain", OPT_DANE_TLSA_DOMAIN, 's', "DANE TLSA base domain"},
{"dane_tlsa_rrdata", OPT_DANE_TLSA_RRDATA, 's',
"DANE TLSA rrdata presentation form"},
{"dane_ee_no_namechecks", OPT_DANE_EE_NO_NAME, '-',
"Disable name checks when matching DANE-EE(3) TLSA records"},
{"reconnect", OPT_RECONNECT, '-',
"Drop and re-make the connection with the same Session-ID"},
{"showcerts", OPT_SHOWCERTS, '-', "Show all certificates in the chain"},
@ -783,6 +785,7 @@ int s_client_main(int argc, char **argv)
STACK_OF(OPENSSL_STRING) *ssl_args = NULL;
char *dane_tlsa_domain = NULL;
STACK_OF(OPENSSL_STRING) *dane_tlsa_rrset = NULL;
int dane_ee_no_name = 0;
STACK_OF(X509_CRL) *crls = NULL;
const SSL_METHOD *meth = TLS_client_method();
const char *CApath = NULL, *CAfile = NULL;
@ -1257,6 +1260,9 @@ int s_client_main(int argc, char **argv)
goto end;
}
break;
case OPT_DANE_EE_NO_NAME:
dane_ee_no_name = 1;
break;
case OPT_NEXTPROTONEG:
#ifndef OPENSSL_NO_NEXTPROTONEG
next_proto_neg_in = opt_arg();
@ -1701,6 +1707,8 @@ int s_client_main(int argc, char **argv)
"records.\n", prog);
goto end;
}
if (dane_ee_no_name)
SSL_dane_set_flags(con, DANE_FLAG_NO_DANE_EE_NAMECHECKS);
} else if (dane_tlsa_rrset != NULL) {
BIO_printf(bio_err, "%s: DANE TLSA authentication requires the "
"-dane_tlsa_domain option.\n", prog);

19
doc/apps/s_client.pod
View file

@ -24,6 +24,7 @@ B<openssl> B<s_client>
[B<-no-CApath>]
[B<-dane_tlsa_domain domain>]
[B<-dane_tlsa_rrdata rrdata>]
[B<-dane_ee_no_namechecks>]
[B<-attime timestamp>]
[B<-check_ss_sig>]
[B<-crl_check>]
@ -225,6 +226,24 @@ whitespace is ignored in the associated data field. For example:
DANE TLSA 2 1 1 ...ee12d2cc90180517616e8a18 matched TA certificate at depth 1
...
=item B<-dane_ee_no_namechecks>
This disables server name checks when authenticating via DANE-EE(3) TLSA
records.
For some applications, primarily web browsers, it is not safe to disable name
checks due to "unknown key share" attacks, in which a malicious server can
convince a client that a connection to a victim server is instead a secure
connection to the malicious server.
The malicious server may then be able to violate cross-origin scripting
restrictions.
Thus, despite the text of RFC7671, name checks are by default enabled for
DANE-EE(3) TLSA records, and can be disabled in applications where it is safe
to do so.
In particular, SMTP and XMPP clients should set this option as SRV and MX
records already make it possible for a remote domain to redirect client
connections to any server of its choice, and in any case SMTP and XMPP clients
do not execute scripts downloaded from remote servers.
=item B<-attime>, B<-check_ss_sig>, B<-crl_check>, B<-crl_check_all>,
B<-explicit_policy>, B<-extended_crl>, B<-ignore_critical>, B<-inhibit_any>,
B<-inhibit_map>, B<-no_alt_chains>, B<-no_check_time>, B<-partial_chain>, B<-policy>,