From: Mateusz Markowicz <ponie...@protonmail.com>
When using "--verify-x509-name [hostname] subject-alt-name" hostname
will now be accepted also when matched against one of the
X509v3 Subject Alternative Name IP or DNS entries (instead of just
Subject's CN).
While at it, fix a few uncrustify complaints to allow committing this
change.
Signed-off-by: Mateusz Markowicz <ponie...@protonmail.com>
---
Changes from v1:
* added missing hunks
---
doc/man-sections/tls-options.rst | 9 ++++---
src/openvpn/options.c | 4 +++
src/openvpn/ssl_verify.c | 32 +++++++++++++++++------
src/openvpn/ssl_verify.h | 1 +
src/openvpn/ssl_verify_backend.h | 9 +++++++
src/openvpn/ssl_verify_mbedtls.c | 12 +++++++++
src/openvpn/ssl_verify_openssl.c | 45 ++++++++++++++++++++++++++++++++
7 files changed, 100 insertions(+), 12 deletions(-)
diff --git a/doc/man-sections/tls-options.rst b/doc/man-sections/tls-options.rst
index d51aff77..257c779a 100644
--- a/doc/man-sections/tls-options.rst
+++ b/doc/man-sections/tls-options.rst
@@ -647,10 +647,11 @@ If the option is inlined, ``algo`` is always
:code:`SHA256`.
Which X.509 name is compared to ``name`` depends on the setting of type.
``type`` can be :code:`subject` to match the complete subject DN
- (default), :code:`name` to match a subject RDN or :code:`name-prefix` to
- match a subject RDN prefix. Which RDN is verified as name depends on the
- ``--x509-username-field`` option. But it defaults to the common name
- (CN), e.g. a certificate with a subject DN
+ (default), :code:`name` to match a subject RDN, :code:`name-prefix` to
+ match a subject RDN prefix or :code:`subject-alt-name` to match the subject
+ SAN (or the CN if SAN is not specified). Which RDN is verified as name
+ depends on the ``--x509-username-field`` option. But it defaults to the
+ common name (CN), e.g. a certificate with a subject DN
::
C=KG, ST=NA, L=Bishkek, CN=Server-1
diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index 4566172b..02f91259 100644
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -8935,6 +8935,10 @@ add_option(struct options *options,
{
type = VERIFY_X509_SUBJECT_RDN_PREFIX;
}
+ else if (streq(p[2], "subject-alt-name"))
+ {
+ type = VERIFY_X509_SAN;
+ }
else
{
msg(msglevel, "unknown X.509 name type: %s", p[2]);
diff --git a/src/openvpn/ssl_verify.c b/src/openvpn/ssl_verify.c
index 76cb9f19..c13f1c45 100644
--- a/src/openvpn/ssl_verify.c
+++ b/src/openvpn/ssl_verify.c
@@ -377,15 +377,31 @@ verify_peer_cert(const struct tls_options *opt,
openvpn_x509_cert_t *peer_cert,
/* verify X509 name or username against --verify-x509-[user]name */
if (opt->verify_x509_type != VERIFY_X509_NONE)
{
- if ( (opt->verify_x509_type == VERIFY_X509_SUBJECT_DN
- && strcmp(opt->verify_x509_name, subject) == 0)
- || (opt->verify_x509_type == VERIFY_X509_SUBJECT_RDN
- && strcmp(opt->verify_x509_name, common_name) == 0)
- || (opt->verify_x509_type == VERIFY_X509_SUBJECT_RDN_PREFIX
- && strncmp(opt->verify_x509_name, common_name,
- strlen(opt->verify_x509_name)) == 0) )
+ bool match;
+ if (opt->verify_x509_type == VERIFY_X509_SAN)
{
- msg(D_HANDSHAKE, "VERIFY X509NAME OK: %s", subject);
+ bool have_alt_names;
+ match = x509v3_is_host_in_alternative_names(peer_cert,
opt->verify_x509_name,
+ &have_alt_names);
+ if (!match && !have_alt_names)
+ {
+ match = (strcmp(opt->verify_x509_name, common_name) == 0);
+ }
+ }
+ else
+ {
+ match = (opt->verify_x509_type == VERIFY_X509_SUBJECT_DN
+ && strcmp(opt->verify_x509_name, subject) == 0)
+ || (opt->verify_x509_type == VERIFY_X509_SUBJECT_RDN
+ && strcmp(opt->verify_x509_name, common_name) == 0)
+ || (opt->verify_x509_type == VERIFY_X509_SUBJECT_RDN_PREFIX
+ && strncmp(opt->verify_x509_name, common_name,
+ strlen(opt->verify_x509_name)) == 0);
+ }
+
+ if (match)
+ {
+ msg(D_HANDSHAKE, "VERIFY X509NAME OK: %s", opt->verify_x509_name);
}
else
{
diff --git a/src/openvpn/ssl_verify.h b/src/openvpn/ssl_verify.h
index 30dfc9bc..214243d8 100644
--- a/src/openvpn/ssl_verify.h
+++ b/src/openvpn/ssl_verify.h
@@ -64,6 +64,7 @@ struct cert_hash_set {
#define VERIFY_X509_SUBJECT_DN 1
#define VERIFY_X509_SUBJECT_RDN 2
#define VERIFY_X509_SUBJECT_RDN_PREFIX 3
+#define VERIFY_X509_SAN 4
enum tls_auth_status
{
diff --git a/src/openvpn/ssl_verify_backend.h b/src/openvpn/ssl_verify_backend.h
index be857960..948daae2 100644
--- a/src/openvpn/ssl_verify_backend.h
+++ b/src/openvpn/ssl_verify_backend.h
@@ -268,4 +268,13 @@ result_t x509_write_pem(FILE *peercert_file,
openvpn_x509_cert_t *peercert);
*/
bool tls_verify_crl_missing(const struct tls_options *opt);
+/**
+ * Return true iff {host} was found in {cert} Subject Alternative Names DNS or
+ * IP entries.
+ * If has_alt_names is not NULL it'll be set to true iff Subject Alternative
+ * Names were defined for cert.
+ */
+bool x509v3_is_host_in_alternative_names(openvpn_x509_cert_t *cert,
+ const char *host, bool *has_alt_name);
+
#endif /* SSL_VERIFY_BACKEND_H_ */
diff --git a/src/openvpn/ssl_verify_mbedtls.c b/src/openvpn/ssl_verify_mbedtls.c
index 5463c8da..228e7fb6 100644
--- a/src/openvpn/ssl_verify_mbedtls.c
+++ b/src/openvpn/ssl_verify_mbedtls.c
@@ -262,6 +262,18 @@ x509_get_subject(mbedtls_x509_crt *cert, struct gc_arena
*gc)
return subject;
}
+bool
+x509v3_is_host_in_alternative_names(mbedtls_x509_crt *cert, const char *host,
+ bool *has_alt_names)
+{
+ msg(M_WARN, "Missing support for subject alternative names in mbedtls.");
+ if (has_alt_names)
+ {
+ *has_alt_names = false;
+ }
+ return false;
+}
+
static void
do_setenv_x509(struct env_set *es, const char *name, char *value, int depth)
{
diff --git a/src/openvpn/ssl_verify_openssl.c b/src/openvpn/ssl_verify_openssl.c
index 78efa70a..3c6f629b 100644
--- a/src/openvpn/ssl_verify_openssl.c
+++ b/src/openvpn/ssl_verify_openssl.c
@@ -376,6 +376,51 @@ err:
return subject;
}
+bool
+x509v3_is_host_in_alternative_names(X509 *cert, const char *host,
+ bool *has_alt_names)
+{
+ GENERAL_NAMES *altnames = X509_get_ext_d2i(cert, NID_subject_alt_name,
NULL, NULL);
+ if (has_alt_names)
+ {
+ *has_alt_names = (altnames != NULL);
+ }
+ if (altnames == NULL)
+ {
+ return false;
+ }
+
+ int n = sk_GENERAL_NAME_num(altnames);
+ for (int i = 0; i < n; i++)
+ {
+ GENERAL_NAME *altname = sk_GENERAL_NAME_value(altnames, i);
+ ASN1_STRING *altname_asn1 = NULL;
+ if (altname->type == GEN_DNS)
+ {
+ altname_asn1 = altname->d.dNSName;
+ }
+ else if (altname->type == GEN_IPADD)
+ {
+ altname_asn1 = altname->d.iPAddress;
+ }
+
+ if (altname_asn1 != NULL)
+ {
+ char *altname_cstr = NULL;
+ if (ASN1_STRING_to_UTF8((unsigned char **)&altname_cstr,
altname_asn1) >= 0)
+ {
+ bool match = strcmp(host, altname_cstr) == 0;
+ OPENSSL_free(altname_cstr);
+ if (match)
+ {
+ return true;
+ }
+ }
+ }
+ }
+ return false;
+}
+
/*
* x509-track implementation -- save X509 fields to environment,
--
2.35.1
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