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samba-mirror/source3/libsmb/spnego.c
Jeremy Allison 894358a8f3 r13915: Fixed a very interesting class of realloc() bugs found by Coverity. 
realloc can return NULL in one of two cases - (1) the realloc failed,
(2) realloc succeeded but the new size requested was zero, in which
case this is identical to a free() call.

The error paths dealing with these two cases should be different,
but mostly weren't. Secondly the standard idiom for dealing with
realloc when you know the new size is non-zero is the following :

 tmp = realloc(p, size);
 if (!tmp) {
    SAFE_FREE(p);
    return error;
 } else {
    p = tmp;
 }

However, there were *many* *many* places in Samba where we were
using the old (broken) idiom of :

 p = realloc(p, size)
 if (!p) {
    return error;
 }

which will leak the memory pointed to by p on realloc fail.

This commit (hopefully) fixes all these cases by moving to
a standard idiom of :

 p = SMB_REALLOC(p, size)
 if (!p) {
    return error;
 }

Where if the realloc returns null due to the realloc failing
or size == 0 we *guarentee* that the storage pointed to by p
has been freed. This allows me to remove a lot of code that
was dealing with the standard (more verbose) method that required
a tmp pointer. This is almost always what you want. When a
realloc fails you never usually want the old memory, you
want to free it and get into your error processing asap.

For the 11 remaining cases where we really do need to keep the
old pointer I have invented the new macro SMB_REALLOC_KEEP_OLD_ON_ERROR,
which can be used as follows :

 tmp = SMB_REALLOC_KEEP_OLD_ON_ERROR(p, size);
 if (!tmp) {
    SAFE_FREE(p);
    return error;
 } else {
    p = tmp;
 }

SMB_REALLOC_KEEP_OLD_ON_ERROR guarentees never to free the
pointer p, even on size == 0 or realloc fail. All this is
done by a hidden extra argument to Realloc(), BOOL free_old_on_error
which is set appropriately by the SMB_REALLOC and SMB_REALLOC_KEEP_OLD_ON_ERROR
macros (and their array counterparts).

It remains to be seen what this will do to our Coverity bug count :-).

Jeremy.
(This used to be commit 1d710d06a2)
2007-10-10 11:10:59 -05:00

348 lines
8.4 KiB
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/*
Unix SMB/CIFS implementation.
RFC2478 Compliant SPNEGO implementation
Copyright (C) Jim McDonough <jmcd@us.ibm.com> 2003
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
#undef DBGC_CLASS
#define DBGC_CLASS DBGC_AUTH
static BOOL read_negTokenInit(ASN1_DATA *asn1, negTokenInit_t *token)
{
ZERO_STRUCTP(token);
asn1_start_tag(asn1, ASN1_CONTEXT(0));
asn1_start_tag(asn1, ASN1_SEQUENCE(0));
while (!asn1->has_error && 0 < asn1_tag_remaining(asn1)) {
int i;
switch (asn1->data[asn1->ofs]) {
/* Read mechTypes */
case ASN1_CONTEXT(0):
asn1_start_tag(asn1, ASN1_CONTEXT(0));
asn1_start_tag(asn1, ASN1_SEQUENCE(0));
token->mechTypes = SMB_MALLOC_P(const char *);
for (i = 0; !asn1->has_error &&
0 < asn1_tag_remaining(asn1); i++) {
char *p_oid = NULL;
token->mechTypes =
SMB_REALLOC_ARRAY(token->mechTypes, const char *, i + 2);
if (!token->mechTypes) {
asn1->has_error = True;
return False;
}
asn1_read_OID(asn1, &p_oid);
token->mechTypes[i] = p_oid;
}
token->mechTypes[i] = NULL;
asn1_end_tag(asn1);
asn1_end_tag(asn1);
break;
/* Read reqFlags */
case ASN1_CONTEXT(1):
asn1_start_tag(asn1, ASN1_CONTEXT(1));
asn1_read_Integer(asn1, &token->reqFlags);
token->reqFlags |= SPNEGO_REQ_FLAG;
asn1_end_tag(asn1);
break;
/* Read mechToken */
case ASN1_CONTEXT(2):
asn1_start_tag(asn1, ASN1_CONTEXT(2));
asn1_read_OctetString(asn1, &token->mechToken);
asn1_end_tag(asn1);
break;
/* Read mecListMIC */
case ASN1_CONTEXT(3):
asn1_start_tag(asn1, ASN1_CONTEXT(3));
if (asn1->data[asn1->ofs] == ASN1_OCTET_STRING) {
asn1_read_OctetString(asn1,
&token->mechListMIC);
} else {
/* RFC 2478 says we have an Octet String here,
but W2k sends something different... */
char *mechListMIC;
asn1_push_tag(asn1, ASN1_SEQUENCE(0));
asn1_push_tag(asn1, ASN1_CONTEXT(0));
asn1_read_GeneralString(asn1, &mechListMIC);
asn1_pop_tag(asn1);
asn1_pop_tag(asn1);
token->mechListMIC =
data_blob(mechListMIC, strlen(mechListMIC));
SAFE_FREE(mechListMIC);
}
asn1_end_tag(asn1);
break;
default:
asn1->has_error = True;
break;
}
}
asn1_end_tag(asn1);
asn1_end_tag(asn1);
return !asn1->has_error;
}
static BOOL write_negTokenInit(ASN1_DATA *asn1, negTokenInit_t *token)
{
asn1_push_tag(asn1, ASN1_CONTEXT(0));
asn1_push_tag(asn1, ASN1_SEQUENCE(0));
/* Write mechTypes */
if (token->mechTypes && *token->mechTypes) {
int i;
asn1_push_tag(asn1, ASN1_CONTEXT(0));
asn1_push_tag(asn1, ASN1_SEQUENCE(0));
for (i = 0; token->mechTypes[i]; i++) {
asn1_write_OID(asn1, token->mechTypes[i]);
}
asn1_pop_tag(asn1);
asn1_pop_tag(asn1);
}
/* write reqFlags */
if (token->reqFlags & SPNEGO_REQ_FLAG) {
int flags = token->reqFlags & ~SPNEGO_REQ_FLAG;
asn1_push_tag(asn1, ASN1_CONTEXT(1));
asn1_write_Integer(asn1, flags);
asn1_pop_tag(asn1);
}
/* write mechToken */
if (token->mechToken.data) {
asn1_push_tag(asn1, ASN1_CONTEXT(2));
asn1_write_OctetString(asn1, token->mechToken.data,
token->mechToken.length);
asn1_pop_tag(asn1);
}
/* write mechListMIC */
if (token->mechListMIC.data) {
asn1_push_tag(asn1, ASN1_CONTEXT(3));
#if 0
/* This is what RFC 2478 says ... */
asn1_write_OctetString(asn1, token->mechListMIC.data,
token->mechListMIC.length);
#else
/* ... but unfortunately this is what Windows
sends/expects */
asn1_push_tag(asn1, ASN1_SEQUENCE(0));
asn1_push_tag(asn1, ASN1_CONTEXT(0));
asn1_push_tag(asn1, ASN1_GENERAL_STRING);
asn1_write(asn1, token->mechListMIC.data,
token->mechListMIC.length);
asn1_pop_tag(asn1);
asn1_pop_tag(asn1);
asn1_pop_tag(asn1);
#endif
asn1_pop_tag(asn1);
}
asn1_pop_tag(asn1);
asn1_pop_tag(asn1);
return !asn1->has_error;
}
static BOOL read_negTokenTarg(ASN1_DATA *asn1, negTokenTarg_t *token)
{
ZERO_STRUCTP(token);
asn1_start_tag(asn1, ASN1_CONTEXT(1));
asn1_start_tag(asn1, ASN1_SEQUENCE(0));
while (!asn1->has_error && 0 < asn1_tag_remaining(asn1)) {
switch (asn1->data[asn1->ofs]) {
case ASN1_CONTEXT(0):
asn1_start_tag(asn1, ASN1_CONTEXT(0));
asn1_start_tag(asn1, ASN1_ENUMERATED);
asn1_read_uint8(asn1, &token->negResult);
asn1_end_tag(asn1);
asn1_end_tag(asn1);
break;
case ASN1_CONTEXT(1):
asn1_start_tag(asn1, ASN1_CONTEXT(1));
asn1_read_OID(asn1, &token->supportedMech);
asn1_end_tag(asn1);
break;
case ASN1_CONTEXT(2):
asn1_start_tag(asn1, ASN1_CONTEXT(2));
asn1_read_OctetString(asn1, &token->responseToken);
asn1_end_tag(asn1);
break;
case ASN1_CONTEXT(3):
asn1_start_tag(asn1, ASN1_CONTEXT(3));
asn1_read_OctetString(asn1, &token->mechListMIC);
asn1_end_tag(asn1);
break;
default:
asn1->has_error = True;
break;
}
}
asn1_end_tag(asn1);
asn1_end_tag(asn1);
return !asn1->has_error;
}
static BOOL write_negTokenTarg(ASN1_DATA *asn1, negTokenTarg_t *token)
{
asn1_push_tag(asn1, ASN1_CONTEXT(1));
asn1_push_tag(asn1, ASN1_SEQUENCE(0));
asn1_push_tag(asn1, ASN1_CONTEXT(0));
asn1_write_enumerated(asn1, token->negResult);
asn1_pop_tag(asn1);
if (token->supportedMech) {
asn1_push_tag(asn1, ASN1_CONTEXT(1));
asn1_write_OID(asn1, token->supportedMech);
asn1_pop_tag(asn1);
}
if (token->responseToken.data) {
asn1_push_tag(asn1, ASN1_CONTEXT(2));
asn1_write_OctetString(asn1, token->responseToken.data,
token->responseToken.length);
asn1_pop_tag(asn1);
}
if (token->mechListMIC.data) {
asn1_push_tag(asn1, ASN1_CONTEXT(3));
asn1_write_OctetString(asn1, token->mechListMIC.data,
token->mechListMIC.length);
asn1_pop_tag(asn1);
}
asn1_pop_tag(asn1);
asn1_pop_tag(asn1);
return !asn1->has_error;
}
ssize_t read_spnego_data(DATA_BLOB data, SPNEGO_DATA *token)
{
ASN1_DATA asn1;
ssize_t ret = -1;
ZERO_STRUCTP(token);
ZERO_STRUCT(asn1);
asn1_load(&asn1, data);
switch (asn1.data[asn1.ofs]) {
case ASN1_APPLICATION(0):
asn1_start_tag(&asn1, ASN1_APPLICATION(0));
asn1_check_OID(&asn1, OID_SPNEGO);
if (read_negTokenInit(&asn1, &token->negTokenInit)) {
token->type = SPNEGO_NEG_TOKEN_INIT;
}
asn1_end_tag(&asn1);
break;
case ASN1_CONTEXT(1):
if (read_negTokenTarg(&asn1, &token->negTokenTarg)) {
token->type = SPNEGO_NEG_TOKEN_TARG;
}
break;
default:
break;
}
if (!asn1.has_error) ret = asn1.ofs;
asn1_free(&asn1);
return ret;
}
ssize_t write_spnego_data(DATA_BLOB *blob, SPNEGO_DATA *spnego)
{
ASN1_DATA asn1;
ssize_t ret = -1;
ZERO_STRUCT(asn1);
switch (spnego->type) {
case SPNEGO_NEG_TOKEN_INIT:
asn1_push_tag(&asn1, ASN1_APPLICATION(0));
asn1_write_OID(&asn1, OID_SPNEGO);
write_negTokenInit(&asn1, &spnego->negTokenInit);
asn1_pop_tag(&asn1);
break;
case SPNEGO_NEG_TOKEN_TARG:
write_negTokenTarg(&asn1, &spnego->negTokenTarg);
break;
default:
asn1.has_error = True;
break;
}
if (!asn1.has_error) {
*blob = data_blob(asn1.data, asn1.length);
ret = asn1.ofs;
}
asn1_free(&asn1);
return ret;
}
BOOL free_spnego_data(SPNEGO_DATA *spnego)
{
BOOL ret = True;
if (!spnego) goto out;
switch(spnego->type) {
case SPNEGO_NEG_TOKEN_INIT:
if (spnego->negTokenInit.mechTypes) {
int i;
for (i = 0; spnego->negTokenInit.mechTypes[i]; i++) {
free(CONST_DISCARD(char *,spnego->negTokenInit.mechTypes[i]));
}
free(spnego->negTokenInit.mechTypes);
}
data_blob_free(&spnego->negTokenInit.mechToken);
data_blob_free(&spnego->negTokenInit.mechListMIC);
break;
case SPNEGO_NEG_TOKEN_TARG:
if (spnego->negTokenTarg.supportedMech) {
free(spnego->negTokenTarg.supportedMech);
}
data_blob_free(&spnego->negTokenTarg.responseToken);
data_blob_free(&spnego->negTokenTarg.mechListMIC);
break;
default:
ret = False;
break;
}
ZERO_STRUCTP(spnego);
out:
return ret;
}
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