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- Improved certificate validation and validation against the available CRLs

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This commit is contained in:
Paul Bakker 2011-01-16 21:12:10 +00:00
parent 43ca69c38a
commit 76fd75a3de
3 changed files with 98 additions and 82 deletions
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6
ChangeLog
View file

@ -8,9 +8,11 @@ Note: Most of these features have been donated by Fox-IT
for integration with OpenVPN
* Added reading of DHM context from memory and file
* Added verification callback on certificate chain
verification to allow external blacklisting.
verification to allow external blacklisting
* Improved X509 certificate parsing to include extended
certificate fields, including Key Usage.
certificate fields, including Key Usage
* Improved certificate verification and verification
against the available CRLs
* Detection for DES weak keys and parity bits added
= Version 0.14.0 released on 2010-08-16

172
library/x509parse.c
View file

@ -2626,6 +2626,69 @@ static void x509_hash( const unsigned char *in, int len, int alg,
}
}
/*
* Check that the given certificate is valid accoring to the CRL.
*/
static int x509parse_verifycrl(x509_cert *crt, x509_cert *ca,
x509_crl *crl_list)
{
int flags = 0;
int hash_id;
unsigned char hash[64];
/*
* TODO: What happens if no CRL is present?
* Suggestion: Revocation state should be unknown if no CRL is present.
* For backwards compatibility this is not yet implemented.
*/
while( ca != NULL && crl_list != NULL && crl_list->version != 0 )
{
if( crl_list->issuer_raw.len != ca->subject_raw.len ||
memcmp( crl_list->issuer_raw.p, ca->subject_raw.p,
crl_list->issuer_raw.len ) != 0 )
{
crl_list = crl_list->next;
continue;
}
/*
* Check if CRL is correctly signed by the trusted CA
*/
hash_id = crl_list->sig_alg;
x509_hash( crl_list->tbs.p, crl_list->tbs.len, hash_id, hash );
if( !rsa_pkcs1_verify( &ca->rsa, RSA_PUBLIC, hash_id,
0, hash, crl_list->sig.p ) == 0 )
{
/*
* CRL is not trusted
*/
flags |= BADCRL_NOT_TRUSTED;
break;
}
/*
* Check for validity of CRL (Do not drop out)
*/
if( x509parse_time_expired( &crl_list->next_update ) )
flags |= BADCRL_EXPIRED;
/*
* Check if certificate is revoked
*/
if( x509parse_revoked(crt, crl_list) )
{
flags |= BADCERT_REVOKED;
break;
}
crl_list = crl_list->next;
}
return flags;
}
/*
* Verify the certificate validity
*/
@ -2639,7 +2702,7 @@ int x509parse_verify( x509_cert *crt,
int cn_len;
int hash_id;
int pathlen;
x509_cert *cur;
x509_cert *parent;
x509_name *name;
unsigned char hash[64];
@ -2667,26 +2730,22 @@ int x509parse_verify( x509_cert *crt,
*flags |= BADCERT_CN_MISMATCH;
}
*flags |= BADCERT_NOT_TRUSTED;
/*
* Iterate upwards in the given cert chain,
* ignoring any upper cert with CA != TRUE.
*/
cur = crt->next;
parent = crt->next;
pathlen = 1;
while( cur != NULL && cur->version != 0 )
while( parent != NULL && parent->version != 0 )
{
int verify_ok = 1;
if( cur->ca_istrue == 0 ||
crt->issuer_raw.len != cur->subject_raw.len ||
memcmp( crt->issuer_raw.p, cur->subject_raw.p,
if( parent->ca_istrue == 0 ||
crt->issuer_raw.len != parent->subject_raw.len ||
memcmp( crt->issuer_raw.p, parent->subject_raw.p,
crt->issuer_raw.len ) != 0 )
{
cur = cur->next;
parent = parent->next;
continue;
}
@ -2694,28 +2753,35 @@ int x509parse_verify( x509_cert *crt,
x509_hash( crt->tbs.p, crt->tbs.len, hash_id, hash );
if( rsa_pkcs1_verify( &cur->rsa, RSA_PUBLIC, hash_id,
0, hash, crt->sig.p ) != 0 )
verify_ok = 0;
if( rsa_pkcs1_verify( &parent->rsa, RSA_PUBLIC, hash_id, 0, hash,
crt->sig.p ) != 0 )
*flags |= BADCERT_NOT_TRUSTED;
/* Check trusted CA's CRL for the given crt */
*flags |= x509parse_verifycrl(crt, parent, ca_crl);
/* crt is verified to be a child of the parent cur, call verify callback */
if( NULL != f_vrfy )
{
if ( f_vrfy( p_vrfy, crt, pathlen-1, verify_ok ) != 0 )
if( f_vrfy( p_vrfy, crt, pathlen - 1, ( *flags == 0 ) ) != 0 )
return( POLARSSL_ERR_X509_CERT_VERIFY_FAILED );
} else if ( verify_ok == 0 ) {
return( POLARSSL_ERR_X509_CERT_VERIFY_FAILED );
else
*flags = 0;
}
else if( *flags != 0 )
return( POLARSSL_ERR_X509_CERT_VERIFY_FAILED );
pathlen++;
crt = cur;
cur = crt->next;
crt = parent;
parent = crt->next;
}
/*
* Atempt to validate topmost cert with our CA chain.
* Attempt to validate topmost cert with our CA chain.
*/
*flags |= BADCERT_NOT_TRUSTED;
while( trust_ca != NULL && trust_ca->version != 0 )
{
if( crt->issuer_raw.len != trust_ca->subject_raw.len ||
@ -2747,71 +2813,19 @@ int x509parse_verify( x509_cert *crt,
trust_ca = trust_ca->next;
}
/*
* TODO: What happens if no CRL is present?
* Suggestion: Revocation state should be unknown if no CRL is present.
* For backwards compatibility this is not yet implemented.
*/
/*
* Check if the topmost certificate is revoked if the trusted CA is
* determined.
*/
while( trust_ca != NULL && ca_crl != NULL && ca_crl->version != 0 )
{
if( ca_crl->issuer_raw.len != trust_ca->subject_raw.len ||
memcmp( ca_crl->issuer_raw.p, trust_ca->subject_raw.p,
ca_crl->issuer_raw.len ) != 0 )
{
ca_crl = ca_crl->next;
continue;
}
/*
* Check if CRL is correctry signed by the trusted CA
*/
hash_id = ca_crl->sig_alg;
x509_hash( ca_crl->tbs.p, ca_crl->tbs.len, hash_id, hash );
if( !rsa_pkcs1_verify( &trust_ca->rsa, RSA_PUBLIC, hash_id,
0, hash, ca_crl->sig.p ) == 0 )
{
/*
* CRL is not trusted
*/
*flags |= BADCRL_NOT_TRUSTED;
break;
}
/*
* Check for validity of CRL (Do not drop out)
*/
if( x509parse_time_expired( &ca_crl->next_update ) )
*flags |= BADCRL_EXPIRED;
/*
* Check if certificate is revoked
*/
if( x509parse_revoked(crt, ca_crl) )
{
*flags |= BADCERT_REVOKED;
break;
}
ca_crl = ca_crl->next;
}
if( *flags != 0 )
return( POLARSSL_ERR_X509_CERT_VERIFY_FAILED );
/* Check trusted CA's CRL for the given crt */
*flags |= x509parse_verifycrl( crt, trust_ca, ca_crl );
/* Verification succeeded, call callback on top cert */
if( NULL != f_vrfy )
{
if ( f_vrfy(p_vrfy, crt, pathlen - 1, 1) != 0 )
if( f_vrfy(p_vrfy, crt, pathlen-1, ( *flags == 0 ) ) != 0 )
return( POLARSSL_ERR_X509_CERT_VERIFY_FAILED );
else
*flags = 0;
}
else if( *flags != 0 )
return( POLARSSL_ERR_X509_CERT_VERIFY_FAILED );
return( 0 );
}

2
tests/suites/test_suite_x509parse.data
View file

@ -167,7 +167,7 @@ depends_on:POLARSSL_SHA4_C
x509_verify:"data_files/cert_sha512.crt":"data_files/test-ca.crt":"data_files/crl.pem":NULL:POLARSSL_ERR_X509_CERT_VERIFY_FAILED:0:&verify_none
X509 Certificate verification #20 (Not trusted Cert, allowing callback)
x509_verify:"data_files/server2.crt":"data_files/server1.crt":"data_files/crl_expired.pem":NULL:POLARSSL_ERR_X509_CERT_VERIFY_FAILED:BADCERT_NOT_TRUSTED:&verify_all
x509_verify:"data_files/server2.crt":"data_files/server1.crt":"data_files/crl_expired.pem":NULL:0:0:&verify_all
X509 Parse Selftest
depends_on:POLARSSL_MD5_C