Move peer chain security checks into x509_vfy.c

A new X509_VERIFY_PARAM_set_auth_level() function sets the
authentication security level.  For verification of SSL peers, this
is automatically set from the SSL security level.  Otherwise, for
now, the authentication security level remains at (effectively) 0
by default.

The new "-auth_level" verify(1) option is available in all the
command-line tools that support the standard verify(1) options.

New verify(1) tests added to check enforcement of chain signature
and public key security levels.  Also added new tests of enforcement
of the verify_depth limit.

Updated documentation.

Reviewed-by: Dr. Stephen Henson <steve@openssl.org>

1 files changed, 37 insertions, 5 deletions

diff --git a/doc/crypto/X509_VERIFY_PARAM_set_flags.pod b/doc/crypto/X509_VERIFY_PARAM_set_flags.pod
index 6fb33edd91..04f521506f 100644
--- a/doc/crypto/X509_VERIFY_PARAM_set_flags.pod
+++ b/doc/crypto/X509_VERIFY_PARAM_set_flags.pod
@@ -2,15 +2,16 @@
 
 =head1 NAME
 
-X509_VERIFY_PARAM_set_flags, X509_VERIFY_PARAM_clear_flags, X509_VERIFY_PARAM_get_flags, X509_VERIFY_PARAM_set_purpose, X509_VERIFY_PARAM_set_trust, X509_VERIFY_PARAM_set_depth, X509_VERIFY_PARAM_get_depth, X509_VERIFY_PARAM_set_time, X509_VERIFY_PARAM_add0_policy, X509_VERIFY_PARAM_set1_policies, X509_VERIFY_PARAM_set1_host, X509_VERIFY_PARAM_add1_host, X509_VERIFY_PARAM_set_hostflags, X509_VERIFY_PARAM_get0_peername, X509_VERIFY_PARAM_set1_email, X509_VERIFY_PARAM_set1_ip, X509_VERIFY_PARAM_set1_ip_asc - X509 verification parameters
+X509_VERIFY_PARAM_set_flags, X509_VERIFY_PARAM_clear_flags, X509_VERIFY_PARAM_get_flags, X509_VERIFY_PARAM_set_purpose, X509_VERIFY_PARAM_set_trust, X509_VERIFY_PARAM_set_depth, X509_VERIFY_PARAM_get_depth, X509_VERIFY_PARAM_set_auth_level, X509_VERIFY_PARAM_get_auth_level, X509_VERIFY_PARAM_set_time, X509_VERIFY_PARAM_add0_policy, X509_VERIFY_PARAM_set1_policies, X509_VERIFY_PARAM_set1_host, X509_VERIFY_PARAM_add1_host, X509_VERIFY_PARAM_set_hostflags, X509_VERIFY_PARAM_get0_peername, X509_VERIFY_PARAM_set1_email, X509_VERIFY_PARAM_set1_ip, X509_VERIFY_PARAM_set1_ip_asc - X509 verification parameters
 
 =head1 SYNOPSIS
 
  #include <openssl/x509_vfy.h>
 
- int X509_VERIFY_PARAM_set_flags(X509_VERIFY_PARAM *param, unsigned long flags);
+ int X509_VERIFY_PARAM_set_flags(X509_VERIFY_PARAM *param,
+                                        unsigned long flags);
  int X509_VERIFY_PARAM_clear_flags(X509_VERIFY_PARAM *param,
-							unsigned long flags);
+					unsigned long flags);
  unsigned long X509_VERIFY_PARAM_get_flags(X509_VERIFY_PARAM *param);
 
  int X509_VERIFY_PARAM_set_purpose(X509_VERIFY_PARAM *param, int purpose);
@@ -19,13 +20,17 @@ X509_VERIFY_PARAM_set_flags, X509_VERIFY_PARAM_clear_flags, X509_VERIFY_PARAM_ge
  void X509_VERIFY_PARAM_set_time(X509_VERIFY_PARAM *param, time_t t);
 
  int X509_VERIFY_PARAM_add0_policy(X509_VERIFY_PARAM *param,
-						ASN1_OBJECT *policy);
+					ASN1_OBJECT *policy);
  int X509_VERIFY_PARAM_set1_policies(X509_VERIFY_PARAM *param, 
 					STACK_OF(ASN1_OBJECT) *policies);
 
  void X509_VERIFY_PARAM_set_depth(X509_VERIFY_PARAM *param, int depth);
  int X509_VERIFY_PARAM_get_depth(const X509_VERIFY_PARAM *param);
 
+ void X509_VERIFY_PARAM_set_auth_level(X509_VERIFY_PARAM *param,
+                                        int auth_level);
+ int X509_VERIFY_PARAM_get_auth_level(const X509_VERIFY_PARAM *param);
+
  int X509_VERIFY_PARAM_set1_host(X509_VERIFY_PARAM *param,
 				 const char *name, size_t namelen);
  int X509_VERIFY_PARAM_add1_host(X509_VERIFY_PARAM *param,
@@ -71,8 +76,32 @@ policy set is cleared. The B<policies> parameter can be B<NULL> to clear
 an existing policy set.
 
 X509_VERIFY_PARAM_set_depth() sets the maximum verification depth to B<depth>.
-That is the maximum number of untrusted CA certificates that can appear in a
+That is the maximum number of intermediate CA certificates that can appear in a
 chain.
+A maximal depth chain contains 2 more certificates than the limit, since
+neither the end-entity ceritificate nor the trust-anchor count against this
+limit.
+Thus a B<depth> limit of 0 only allows the end-entity certificate to be signed
+directly by the trust-anchor, while with a B<depth> limit of 1 there can be one
+intermediate CA certificate between the trust-anchor and the end-entity
+certificate.
+
+X509_VERIFY_PARAM_set_auth_level() sets the authentication security level to
+B<auth_level>.
+The authentication security level determines the acceptable signature and public
+key strength when verifying certificate chains.
+For a certificate chain to validate, the public keys of all the certificates
+must meet the specified security level.
+The signature algorithm security level is not enforced for the chain's I<trust
+anchor> certificate, which is either directly trusted or validated by means other
+than its signature.
+See L<SSL_CTX_set_security_level(3)> for the definitions of the available
+levels.
+The default security level is -1, or "not set".
+At security level 0 or lower all algorithms are acceptable.
+Security level 1 requires at least 80-bit-equivalent security and is broadly
+interoperable, though it will, for example, reject MD5 signatures or RSA keys
+shorter than 1024 bits.
 
 X509_VERIFY_PARAM_set1_host() sets the expected DNS hostname to
 B<name> clearing any previously specified host name or names.  If
@@ -139,6 +168,9 @@ values.
 
 X509_VERIFY_PARAM_get_depth() returns the current verification depth.
 
+X509_VERIFY_PARAM_get_auth_level() returns the current authentication security
+level.
+
 =head1 VERIFICATION FLAGS
 
 The verification flags consists of zero or more of the following flags