New docs and new facts in older docs.
Submitted by Lutz Jaenicke <Lutz.Jaenicke@aet.TU-Cottbus.DE>
This commit is contained in:
Richard Levitte
parent
924046ce75
commit
553615f500
50
doc/ssl/SSL_CTX_get_verify_mode.pod
Normal file
50
doc/ssl/SSL_CTX_get_verify_mode.pod
Normal file
@ -0,0 +1,50 @@
|
||||
=pod
|
||||
|
||||
=head1 NAME
|
||||
|
||||
SSL_CTX_get_verify_mode, SSL_get_verify_mode, SSL_CTX_get_verify_depth, SSL_get_verify_depth, SSL_get_verify_callback, SSL_CTX_get_verify_callback - get currently set verification parameters
|
||||
|
||||
=head1 SYNOPSIS
|
||||
|
||||
#include <openssl/ssl.h>
|
||||
|
||||
int SSL_CTX_get_verify_mode(SSL_CTX *ctx);
|
||||
int SSL_get_verify_mode(SSL *ssl);
|
||||
int SSL_CTX_get_verify_depth(SSL_CTX *ctx);
|
||||
int SSL_get_verify_depth(SSL *ssl);
|
||||
int (*SSL_CTX_get_verify_callback(SSL_CTX *ctx))(int, X509_STORE_CTX *);
|
||||
int (*SSL_get_verify_callback(SSL *ssl))(int, X509_STORE_CTX *);
|
||||
|
||||
=head1 DESCRIPTION
|
||||
|
||||
SSL_CTX_get_verify_mode() returns the verification mode currently set in
|
||||
B<ctx>.
|
||||
|
||||
SSL_get_verify_mode() returns the verification mode currently set in
|
||||
B<ssl>.
|
||||
|
||||
SSL_CTX_get_verify_depth() returns the verification depth limit currently set
|
||||
in B<ctx>. If no limit has been explicitly set, -1 is returned and the
|
||||
default value will be used.
|
||||
|
||||
SSL_get_verify_depth() returns the verification depth limit currently set
|
||||
in B<ssl>. If no limit has been explicitly set, -1 is returned and the
|
||||
default value will be used.
|
||||
|
||||
SSL_CTX_get_verify_callback() returns a function pointer to the verification
|
||||
callback currently set in B<ctx>. If no callback was explicitly set, the
|
||||
NULL pointer is returned and the default callback will be used.
|
||||
|
||||
SSL_get_verify_callback() returns a function pointer to the verification
|
||||
callback currently set in B<ssl>. If no callback was explicitly set, the
|
||||
NULL pointer is returned and the default callback will be used.
|
||||
|
||||
=head1 RETURN VALUES
|
||||
|
||||
See DESCRIPTION
|
||||
|
||||
=head1 SEE ALSO
|
||||
|
||||
L<ssl(3)|ssl(3)>, L<SSL_CTX_set_verify(3)|SSL_CTX_set_verify(3)>
|
||||
|
||||
=cut
|
||||
@ -40,6 +40,10 @@ as available CAs during the TLS/SSL handshake.
|
||||
If B<CApath> is not NULL, it points to a directory containing CA certificates
|
||||
in PEM format. The files each contain one CA certificate. The files are
|
||||
looked up by the CA subject name hash value, which must hence be available.
|
||||
If more than one CA certificate with the same name hash value exist, the
|
||||
extension must be different (e.g. 9d66eef0.0, 9d66eef0.1 etc). The search
|
||||
is performed in the ordering of the extension number, regardless of other
|
||||
properties of the certificates.
|
||||
Use the B<c_rehash> utility to create the necessary links.
|
||||
|
||||
The certificates in B<CAfile> are only looked up when required, e.g. when
|
||||
@ -49,6 +53,24 @@ of a peer certificate.
|
||||
On a server, the certificates in B<CApath> are not listed as available
|
||||
CA certificates to a client during a TLS/SSL handshake.
|
||||
|
||||
When looking up CA certificates, the OpenSSL library will first search the
|
||||
certificates in B<CAfile>, then those in B<CApath>. Certificate matching
|
||||
is done based on the subject name, the key identifier (if present), and the
|
||||
serial number as taken from the certificate to be verified. If these data
|
||||
do not match, the next certificate will be tried. If a first certificate
|
||||
matching the parameters is found, the verification process will be performed;
|
||||
no other certificates for the same parameters will be searched in case of
|
||||
failure.
|
||||
|
||||
=head1 WARNINGS
|
||||
|
||||
If several CA certificates matching the name, key identifier, and serial
|
||||
number condition are available, only the first one will be examined. This
|
||||
may lead to unexpected results if the same CA certificate is available
|
||||
with different expiration dates. If a "certificate expired" verification
|
||||
error occurs, no other certificate will be searched. Make sure to not
|
||||
have expired certificates mixed with valid ones.
|
||||
|
||||
=head1 EXAMPLES
|
||||
|
||||
Generate a CA certificate file with descriptive text from the CA certificates
|
||||
|
||||
251
doc/ssl/SSL_CTX_set_verify.pod
Normal file
251
doc/ssl/SSL_CTX_set_verify.pod
Normal file
@ -0,0 +1,251 @@
|
||||
=pod
|
||||
|
||||
=head1 NAME
|
||||
|
||||
SSL_CTX_set_verify, SSL_set_verify, SSL_CTX_set_verify_depth, SSL_set_verify_depth - set peer certificate verification parameters
|
||||
|
||||
=head1 SYNOPSIS
|
||||
|
||||
#include <openssl/ssl.h>
|
||||
|
||||
void SSL_CTX_set_verify(SSL_CTX *ctx, int mode,
|
||||
int (*verify_callback)(int, X509_STORE_CTX *));
|
||||
void SSL_set_verify(SSL *s, int mode,
|
||||
int (*verify_callback)(int, X509_STORE_CTX *));
|
||||
void SSL_CTX_set_verify_depth(SSL_CTX *ctx,int depth);
|
||||
void SSL_set_verify_depth(SSL *s, int depth);
|
||||
|
||||
int verify_callback(int preverify_ok, X509_STORE_CTX *x509_ctx);
|
||||
|
||||
=head1 DESCRIPTION
|
||||
|
||||
SSL_CTX_set_verify() sets the verification flags for B<ctx> to be B<mode> and
|
||||
specifies the B<verify_callback> function to be used. If no callback function
|
||||
shall be specified, the NULL pointer can be used for B<verify_callback>.
|
||||
|
||||
SSL_set_verify() sets the verification flags for B<ssl> to be B<mode> and
|
||||
specifies the B<verify_callback> function to be used. If no callback function
|
||||
shall be specified, the NULL pointer can be used for B<verify_callback>. In
|
||||
this case last B<verify_callback> set specifically for this B<ssl> remains. If
|
||||
no special B<callback> was set before, the default callback for the underlying
|
||||
B<ctx> is used, that was valid at the the time B<ssl> was created with
|
||||
L<SSL_new(3)|SSL_new(3)>.
|
||||
|
||||
SSL_CTX_set_verify_depth() sets the maximum B<depth> for the certificate chain
|
||||
verification that shall be allowed for B<ctx>. (See the BUGS section.)
|
||||
|
||||
SSL_set_verify_depth() sets the maximum B<depth> for the certificate chain
|
||||
verification that shall be allowed for B<ssl>. (See the BUGS section.)
|
||||
|
||||
=head1 NOTES
|
||||
|
||||
The verification of certificates can be controlled by a set of logically
|
||||
or'ed B<mode> flags:
|
||||
|
||||
=over 4
|
||||
|
||||
=item SSL_VERIFY_NONE
|
||||
|
||||
B<Server mode:> the server will not send a client certificate request to the
|
||||
client, so the client will not send a certificate.
|
||||
|
||||
B<Client mode:> if not using an anonymous cipher (by default disabled), the
|
||||
server will send a certificate which will be checked. The result of the
|
||||
certificate verification process can be checked after the TLS/SSL handshake
|
||||
using the L<SSL_get_verify_result(3)|SSL_get_verify_result(3)> function.
|
||||
The handshake will be continued regardless of the verification result.
|
||||
|
||||
=item SSL_VERIFY_PEER
|
||||
|
||||
B<Server mode:> the server sends a client certificate request to the client.
|
||||
The certificate returned (if any) is checked. If the verification process
|
||||
fails as indicated by B<verify_callback>, the TLS/SSL handshake is
|
||||
immediately terminated with an alert message containing the reason for
|
||||
the verification failure.
|
||||
The behaviour can be controlled by the additional
|
||||
SSL_VERIFY_FAIL_IF_NO_PEER_CERT and SSL_VERIFY_CLIENT_ONCE flags.
|
||||
|
||||
B<Client mode:> the server certificate is verified. If the verification process
|
||||
fails as indicated by B<verify_callback>, the TLS/SSL handshake is
|
||||
immediately terminated with an alert message containing the reason for
|
||||
the verification failure. If no server certificate is sent, because an
|
||||
anonymous cipher is used, SSL_VERIFY_PEER is ignored.
|
||||
|
||||
=item SSL_VERIFY_FAIL_IF_NO_PEER_CERT
|
||||
|
||||
B<Server mode:> if the client did not return a certificate, the TLS/SSL
|
||||
handshake is immediately terminated with a "handshake failure" alert.
|
||||
This flag must be used together with SSL_VERIFY_PEER.
|
||||
|
||||
B<Client mode:> ignored
|
||||
|
||||
=item SSL_VERIFY_CLIENT_ONCE
|
||||
|
||||
B<Server mode:> only request a client certificate on the initial TLS/SSL
|
||||
handshake. Do not ask for a client certificate again in case of a
|
||||
renegotiation. This flag must be used together with SSL_VERIFY_PEER.
|
||||
|
||||
B<Client mode:> ignored
|
||||
|
||||
=back
|
||||
|
||||
Exactly one of the B<mode> flags SSL_VERIFY_NONE and SSL_VERIFY_PEER must be
|
||||
set at any time.
|
||||
|
||||
SSL_CTX_set_verify_depth() and SSL_set_verify_depth() set the limit up
|
||||
to which depth certificates in a chain are used during the verification
|
||||
procedure. If the certificate chain is longer than allowed, the certificates
|
||||
above the limit are ignored. Error messages are generated as if these
|
||||
certificates would not be present, most likely a
|
||||
X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY will be issued.
|
||||
The depth count is "level 0:peer certificate", "level 1: CA certificate",
|
||||
"level 2: higher level CA certificate", and so on. Setting the maximum
|
||||
depth to 2 allows the levels 0, 1, and 2. The default depth limit is 9,
|
||||
allowing for the peer certificate and additional 9 CA certificates.
|
||||
|
||||
The B<verify_callback> function is used to control the behaviour when the
|
||||
SSL_VERIFY_PEER flag is set. It must be supplied by the application and
|
||||
receives two arguments: B<preverify_ok> indicates, whether the verification of
|
||||
the certificate in question was passed (preverify_ok=1) or not
|
||||
(preverify_ok=0). B<x509_ctx> is a pointer to the complete context used
|
||||
for the certificate chain verification.
|
||||
|
||||
The certificate chain is checked starting with the deepest nesting level
|
||||
(the root CA certificate) and worked upward to the peer's certificate.
|
||||
At each level signatures and issuer attributes are checked. Whenever
|
||||
a verification error is found, the error number is stored in B<x509_ctx>
|
||||
and B<verify_callback> is called with B<preverify_ok>=0. By applying
|
||||
X509_CTX_store_* functions B<verify_callback> can locate the certificate
|
||||
in question and perform additional steps (see EXAMPLES). If no error is
|
||||
found for a certificate, B<verify_callback> is called with B<preverify_ok>=1
|
||||
before advancing to the next level.
|
||||
|
||||
The return value of B<verify_callback> controls the strategy of the further
|
||||
verification process. If B<verify_callback> returns 0, the verification
|
||||
process is immediately stopped with "verification failed" state. If
|
||||
SSL_VERIFY_PEER is set, a verification failure alert is sent to the peer and
|
||||
the TLS/SSL handshake is terminated. If B<verify_callback> returns 1,
|
||||
the verification process is continued. If B<verify_callback> always returns
|
||||
1, the TLS/SSL handshake will never be terminated because of this application
|
||||
experiencing a verification failure. The calling process can however
|
||||
retrieve the error code of the last verification error using
|
||||
L<SSL_get_verify_result(3)|SSL_get_verify_result(3)> or by maintaining its
|
||||
own error storage managed by B<verify_callback>.
|
||||
|
||||
If no B<verify_callback> is specified, the default callback will be used.
|
||||
Its return value is identical to B<preverify_ok>, so that any verification
|
||||
failure will lead to a termination of the TLS/SSL handshake with an
|
||||
alert message, if SSL_VERIFY_PEER is set.
|
||||
|
||||
=head1 BUGS
|
||||
|
||||
In client mode, it is not checked whether the SSL_VERIFY_PEER flag
|
||||
is set, but whether SSL_VERIFY_NONE is not set. This can lead to
|
||||
unexpected behaviour, if the SSL_VERIFY_PEER and SSL_VERIFY_NONE are not
|
||||
used as required (exactly one must be set at any time).
|
||||
|
||||
The certificate verification depth set with SSL[_CTX]_verify_depth()
|
||||
stops the verification at a certain depth. The error message produced
|
||||
will be that of an incomplete certificate chain and not
|
||||
X509_V_ERR_CERT_CHAIN_TOO_LONG as may be expected.
|
||||
|
||||
=head1 RETURN VALUES
|
||||
|
||||
The SSL*_set_verify*() functions do not provide diagnostic information.
|
||||
|
||||
=head1 EXAMPLES
|
||||
|
||||
The following code sequence realizes an example B<verify_callback> function
|
||||
that will always continue the TLS/SSL handshake regardless of verification
|
||||
failure, if wished. The callback realizes a verification depth limit with
|
||||
more informational output.
|
||||
|
||||
All verification errors are printed, informations about the certificate chain
|
||||
are printed on request.
|
||||
The example is realized for a server that does allow but not require client
|
||||
certificates.
|
||||
|
||||
...
|
||||
int verbose_mode;
|
||||
int verify_depth;
|
||||
int always_continue;
|
||||
...
|
||||
static int verify_callback(int preverify_ok, X509_STORE_CTX *ctx)
|
||||
{
|
||||
char buf[256];
|
||||
X509 *err_cert;
|
||||
int err, depth;
|
||||
|
||||
err_cert = X509_STORE_CTX_get_current_cert(ctx);
|
||||
err = X509_STORE_CTX_get_error(ctx);
|
||||
depth = X509_STORE_CTX_get_error_depth(ctx);
|
||||
|
||||
X509_NAME_oneline(X509_get_subject_name(err_cert), buf, 256);
|
||||
|
||||
/*
|
||||
* Catch a too long certificate chain. The depth limit set using
|
||||
* SSL_CTX_set_verify_depth() is by purpose set to "limit+1" so
|
||||
* that whenever the "depth>verify_depth" condition is met, we
|
||||
* have violated the limit and want to log this error condition.
|
||||
* We must do it here, because the CHAIN_TO_LONG error would not
|
||||
* be found explicitly; only errors introduced by cutting off the
|
||||
* additional certificates would be logged.
|
||||
*/
|
||||
if (depth > verify_depth) {
|
||||
preverify_ok = 0;
|
||||
err = X509_V_ERR_CERT_CHAIN_TOO_LONG;
|
||||
X509_STORE_CTX_set_error(ctx, err);
|
||||
}
|
||||
if (!preverify_ok) {
|
||||
printf("verify error:num=%d:%s:depth=%d:%s\n", err,
|
||||
X509_verify_cert_error_string(err), depth, buf);
|
||||
}
|
||||
else if (verbose_mode)
|
||||
{
|
||||
printf("depth=%d:%s\n", depth, buf);
|
||||
}
|
||||
|
||||
/*
|
||||
* At this point, err contains the last verification error. We can use
|
||||
* it for something special
|
||||
*/
|
||||
if (!preverify_ok && (err == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT)
|
||||
{
|
||||
X509_NAME_oneline(X509_get_issuer_name(ctx->current_cert), buf, 256);
|
||||
printf("issuer= %s\n", buf);
|
||||
}
|
||||
|
||||
if (always_continue)
|
||||
return 1;
|
||||
else
|
||||
return preverify_ok;
|
||||
}
|
||||
...
|
||||
SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER|SSL_VERIFY_CLIENT_ONCE,
|
||||
verify_callback);
|
||||
|
||||
/*
|
||||
* Let the verify_callback catch the verify_depth error so that we get
|
||||
* an appropriate error in the logfile.
|
||||
*/
|
||||
SSL_CTX_set_verify_depth(verify_depth + 1);
|
||||
|
||||
...
|
||||
SSL_accept(ssl); /* check of success left out for clarity */
|
||||
if (peer = SSL_get_peer_certificate(ssl))
|
||||
{
|
||||
if (SSL_get_verify_result(ssl) == X509_V_OK)
|
||||
{
|
||||
/* The client sent a certificate which verified OK */
|
||||
}
|
||||
}
|
||||
|
||||
=head1 SEE ALSO
|
||||
|
||||
L<ssl(3)|ssl(3)>, L<SSL_new(3)|SSL_new(3)>,
|
||||
L<SSL_CTX_get_verify_mode(3)|SSL_CTX_get_verify_mode(3)>,
|
||||
L<SSL_get_verify_result(3)|SSL_get_verify_result(3)>,
|
||||
L<SSL_CTX_load_verify_locations(3)|SSL_CTX_load_verify_locations(3)>,
|
||||
L<SSL_get_peer_certificate(3)|SSL_get_peer_certificate(3)>
|
||||
|
||||
=cut
|
||||
@ -626,10 +626,13 @@ connection defined in the B<SSL> structure.
|
||||
L<openssl(1)|openssl(1)>, L<crypto(3)|crypto(3)>,
|
||||
L<SSL_accept(3)|SSL_accept(3)>, L<SSL_clear(3)|SSL_clear(3)>,
|
||||
L<SSL_connect(3)|SSL_connect(3)>,
|
||||
L<SSL_CIPHER_get_name(3)|SSL_CIPHER_get_name(3)>,
|
||||
L<SSL_CTX_get_verify_mode(3)|SSL_CTX_get_verify_mode(3)>,
|
||||
L<SSL_CTX_load_verify_locations(3)|SSL_CTX_load_verify_locations(3)>
|
||||
L<SSL_CTX_new(3)|SSL_CTX_new(3)>,
|
||||
L<SSL_CTX_set_client_CA_list(3)|SSL_CTX_set_client_CA_list(3)>
|
||||
L<SSL_CTX_set_ssl_version(3)|SSL_CTX_set_ssl_version(3)>,
|
||||
L<SSL_CTX_set_verify(3)|SSL_CTX_set_verify(3)>,
|
||||
L<SSL_get_ciphers(3)|SSL_get_ciphers(3)>,
|
||||
L<SSL_get_client_CA_list(3)|SSL_get_client_CA_list(3)>,
|
||||
L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_get_fd(3)|SSL_get_fd(3)>,
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user