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Try better guessing what is mech we are going to select by looking

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harder at the input_token, idea from Luke Howard's mechglue branch.


git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@18981 ec53bebd-3082-4978-b11e-865c3cabbd6b
This commit is contained in:
Love Hörnquist Åstrand
2006-11-10 03:30:12 +00:00
parent 4aa34c791e
commit 53eeb7198a
1 changed files with 105 additions and 55 deletions
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160
lib/gssapi/mech/gss_accept_sec_context.c
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@@ -29,6 +29,107 @@
#include "mech_locl.h"
RCSID("$Id$");
static OM_uint32
parse_header(const gss_buffer_t input_token, gss_OID mech_oid)
{
unsigned char *p = input_token->value;
size_t len = input_token->length;
size_t a, b;
/*
* Token must start with [APPLICATION 0] SEQUENCE.
* But if it doesn't assume its DCE-STYLE Kerberos!
*/
if (len == 0)
return (GSS_S_DEFECTIVE_TOKEN);
p++;
len--;
/*
* Decode the length and make sure it agrees with the
* token length.
*/
if (len == 0)
return (GSS_S_DEFECTIVE_TOKEN);
if ((*p & 0x80) == 0) {
a = *p;
p++;
len--;
} else {
b = *p & 0x7f;
p++;
len--;
if (len < b)
return (GSS_S_DEFECTIVE_TOKEN);
a = 0;
while (b) {
a = (a << 8) | *p;
p++;
len--;
b--;
}
}
if (a != len)
return (GSS_S_DEFECTIVE_TOKEN);
/*
* Decode the OID for the mechanism. Simplify life by
* assuming that the OID length is less than 128 bytes.
*/
if (len < 2 || *p != 0x06)
return (GSS_S_DEFECTIVE_TOKEN);
if ((p[1] & 0x80) || p[1] > (len - 2))
return (GSS_S_DEFECTIVE_TOKEN);
mech_oid->length = p[1];
p += 2;
len -= 2;
mech_oid->elements = p;
return GSS_S_COMPLETE;
}
static gss_OID_desc krb5_mechanism =
{9, rk_UNCONST("\x2a\x86\x48\x86\xf7\x12\x01\x02\x02")};
static gss_OID_desc spnego_mechanism =
{6, rk_UNCONST("\x2b\x06\x01\x05\x05\x02")};
static OM_uint32
choose_mech(const gss_buffer_t input, gss_OID mech_oid)
{
OM_uint32 status;
/*
* First try to parse the gssapi token header and see if its a
* correct header, use that in the first hand.
*/
status = parse_header(input, mech_oid);
if (status == GSS_S_COMPLETE)
return GSS_S_COMPLETE;
/*
* Lets guess what mech is really is, callback function to mech ??
*/
if (input->length != 0 && ((const char *)input->value)[0] == 0x6E) {
/* Could be a raw AP-REQ (check for APPLICATION tag) */
*mech_oid = krb5_mechanism;
return GSS_S_COMPLETE;
} else if (input->length == 0) {
/*
* There is the a wiered mode of SPNEGO (in CIFS and
* SASL GSS-SPENGO where the first token is zero
* length and the acceptor returns a mech_list, lets
* home that is what is happening now.
*/
*mech_oid = spnego_mechanism;
return GSS_S_COMPLETE;
}
return status;
}
OM_uint32 gss_accept_sec_context(OM_uint32 *minor_status,
gss_ctx_id_t *context_handle,
const gss_cred_id_t acceptor_cred_handle,
@@ -64,63 +165,12 @@ OM_uint32 gss_accept_sec_context(OM_uint32 *minor_status,
* parse the input token to figure out the mechanism to use.
*/
if (*context_handle == GSS_C_NO_CONTEXT) {
unsigned char *p = input_token->value;
size_t len = input_token->length;
size_t a, b;
gss_OID_desc mech_oid;
/*
* Token must start with [APPLICATION 0] SEQUENCE.
* But if it doesn't assume its DCE-STYLE Kerberos!
*/
if (len == 0)
return (GSS_S_DEFECTIVE_TOKEN);
if (*p != 0x60) {
mech_oid = *GSS_KRB5_MECHANISM;
} else {
p++;
len--;
/*
* Decode the length and make sure it agrees with the
* token length.
*/
if (len == 0)
return (GSS_S_DEFECTIVE_TOKEN);
if ((*p & 0x80) == 0) {
a = *p;
p++;
len--;
} else {
b = *p & 0x7f;
p++;
len--;
if (len < b)
return (GSS_S_DEFECTIVE_TOKEN);
a = 0;
while (b) {
a = (a << 8) | *p;
p++;
len--;
b--;
}
}
if (a != len)
return (GSS_S_DEFECTIVE_TOKEN);
/*
* Decode the OID for the mechanism. Simplify life by
* assuming that the OID length is less than 128 bytes.
*/
if (len < 2 || *p != 0x06)
return (GSS_S_DEFECTIVE_TOKEN);
if ((p[1] & 0x80) || p[1] > (len - 2))
return (GSS_S_DEFECTIVE_TOKEN);
mech_oid.length = p[1];
p += 2;
len -= 2;
mech_oid.elements = p;
}
major_status = choose_mech(input_token, &mech_oid);
if (major_status != GSS_S_COMPLETE)
return major_status;
/*
* Now that we have a mechanism, we can find the
* implementation.