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heimdal/lib/krb5/pac.c
Simon Wilkinson e50faea7f0 krb5: Store a digest context in the crypto structure 
Creating and destroying an EVP_CTX_MD structure with every hash
operation is very expensive. Speed things up by caching one within
the krb5_crypto structure. krb5_crypto can already only be safely
used by one thread at a time - adding a message digest context here
shouldn't introduce any further threading risks.

Users of the stashed context must be careful to ensure that they
call no other hash functions whilst they are in the middle of using
the context.
2018-05-23 09:54:27 -04:00

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/*
* Copyright (c) 2006 - 2017 Kungliga Tekniska Högskolan
* (Royal Institute of Technology, Stockholm, Sweden).
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "krb5_locl.h"
#include <wind.h>
struct PAC_INFO_BUFFER {
uint32_t type;
uint32_t buffersize;
uint32_t offset_hi;
uint32_t offset_lo;
};
struct PACTYPE {
uint32_t numbuffers;
uint32_t version;
struct PAC_INFO_BUFFER buffers[1];
};
struct krb5_pac_data {
struct PACTYPE *pac;
krb5_data data;
struct PAC_INFO_BUFFER *server_checksum;
struct PAC_INFO_BUFFER *privsvr_checksum;
struct PAC_INFO_BUFFER *logon_name;
};
#define PAC_ALIGNMENT 8
#define PACTYPE_SIZE 8
#define PAC_INFO_BUFFER_SIZE 16
#define PAC_SERVER_CHECKSUM 6
#define PAC_PRIVSVR_CHECKSUM 7
#define PAC_LOGON_NAME 10
#define PAC_CONSTRAINED_DELEGATION 11
#define CHECK(r,f,l) \
do { \
if (((r) = f ) != 0) { \
krb5_clear_error_message(context); \
goto l; \
} \
} while(0)
static const char zeros[PAC_ALIGNMENT] = { 0 };
/*
* HMAC-MD5 checksum over any key (needed for the PAC routines)
*/
static krb5_error_code
HMAC_MD5_any_checksum(krb5_context context,
const krb5_keyblock *key,
const void *data,
size_t len,
unsigned usage,
Checksum *result)
{
struct _krb5_key_data local_key;
struct krb5_crypto_iov iov;
krb5_error_code ret;
memset(&local_key, 0, sizeof(local_key));
ret = krb5_copy_keyblock(context, key, &local_key.key);
if (ret)
return ret;
ret = krb5_data_alloc (&result->checksum, 16);
if (ret) {
krb5_free_keyblock(context, local_key.key);
return ret;
}
result->cksumtype = CKSUMTYPE_HMAC_MD5;
iov.data.data = (void *)data;
iov.data.length = len;
iov.flags = KRB5_CRYPTO_TYPE_DATA;
ret = _krb5_HMAC_MD5_checksum(context, NULL, &local_key, usage, &iov, 1,
result);
if (ret)
krb5_data_free(&result->checksum);
krb5_free_keyblock(context, local_key.key);
return ret;
}
/*
*
*/
KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_pac_parse(krb5_context context, const void *ptr, size_t len,
krb5_pac *pac)
{
krb5_error_code ret;
krb5_pac p;
krb5_storage *sp = NULL;
uint32_t i, tmp, tmp2, header_end;
p = calloc(1, sizeof(*p));
if (p == NULL) {
ret = krb5_enomem(context);
goto out;
}
sp = krb5_storage_from_readonly_mem(ptr, len);
if (sp == NULL) {
ret = krb5_enomem(context);
goto out;
}
krb5_storage_set_flags(sp, KRB5_STORAGE_BYTEORDER_LE);
CHECK(ret, krb5_ret_uint32(sp, &tmp), out);
CHECK(ret, krb5_ret_uint32(sp, &tmp2), out);
if (tmp < 1) {
ret = EINVAL; /* Too few buffers */
krb5_set_error_message(context, ret, N_("PAC have too few buffer", ""));
goto out;
}
if (tmp2 != 0) {
ret = EINVAL; /* Wrong version */
krb5_set_error_message(context, ret,
N_("PAC have wrong version %d", ""),
(int)tmp2);
goto out;
}
p->pac = calloc(1,
sizeof(*p->pac) + (sizeof(p->pac->buffers[0]) * (tmp - 1)));
if (p->pac == NULL) {
ret = krb5_enomem(context);
goto out;
}
p->pac->numbuffers = tmp;
p->pac->version = tmp2;
header_end = PACTYPE_SIZE + (PAC_INFO_BUFFER_SIZE * p->pac->numbuffers);
if (header_end > len) {
ret = EINVAL;
goto out;
}
for (i = 0; i < p->pac->numbuffers; i++) {
CHECK(ret, krb5_ret_uint32(sp, &p->pac->buffers[i].type), out);
CHECK(ret, krb5_ret_uint32(sp, &p->pac->buffers[i].buffersize), out);
CHECK(ret, krb5_ret_uint32(sp, &p->pac->buffers[i].offset_lo), out);
CHECK(ret, krb5_ret_uint32(sp, &p->pac->buffers[i].offset_hi), out);
/* consistency checks */
if (p->pac->buffers[i].offset_lo & (PAC_ALIGNMENT - 1)) {
ret = EINVAL;
krb5_set_error_message(context, ret,
N_("PAC out of allignment", ""));
goto out;
}
if (p->pac->buffers[i].offset_hi) {
ret = EINVAL;
krb5_set_error_message(context, ret,
N_("PAC high offset set", ""));
goto out;
}
if (p->pac->buffers[i].offset_lo > len) {
ret = EINVAL;
krb5_set_error_message(context, ret,
N_("PAC offset off end", ""));
goto out;
}
if (p->pac->buffers[i].offset_lo < header_end) {
ret = EINVAL;
krb5_set_error_message(context, ret,
N_("PAC offset inside header: %lu %lu", ""),
(unsigned long)p->pac->buffers[i].offset_lo,
(unsigned long)header_end);
goto out;
}
if (p->pac->buffers[i].buffersize > len - p->pac->buffers[i].offset_lo){
ret = EINVAL;
krb5_set_error_message(context, ret, N_("PAC length off end", ""));
goto out;
}
/* let save pointer to data we need later */
if (p->pac->buffers[i].type == PAC_SERVER_CHECKSUM) {
if (p->server_checksum) {
ret = EINVAL;
krb5_set_error_message(context, ret,
N_("PAC have two server checksums", ""));
goto out;
}
p->server_checksum = &p->pac->buffers[i];
} else if (p->pac->buffers[i].type == PAC_PRIVSVR_CHECKSUM) {
if (p->privsvr_checksum) {
ret = EINVAL;
krb5_set_error_message(context, ret,
N_("PAC have two KDC checksums", ""));
goto out;
}
p->privsvr_checksum = &p->pac->buffers[i];
} else if (p->pac->buffers[i].type == PAC_LOGON_NAME) {
if (p->logon_name) {
ret = EINVAL;
krb5_set_error_message(context, ret,
N_("PAC have two logon names", ""));
goto out;
}
p->logon_name = &p->pac->buffers[i];
}
}
ret = krb5_data_copy(&p->data, ptr, len);
if (ret)
goto out;
krb5_storage_free(sp);
*pac = p;
return 0;
out:
if (sp)
krb5_storage_free(sp);
if (p) {
if (p->pac)
free(p->pac);
free(p);
}
*pac = NULL;
return ret;
}
KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_pac_init(krb5_context context, krb5_pac *pac)
{
krb5_error_code ret;
krb5_pac p;
p = calloc(1, sizeof(*p));
if (p == NULL) {
return krb5_enomem(context);
}
p->pac = calloc(1, sizeof(*p->pac));
if (p->pac == NULL) {
free(p);
return krb5_enomem(context);
}
ret = krb5_data_alloc(&p->data, PACTYPE_SIZE);
if (ret) {
free (p->pac);
free(p);
return krb5_enomem(context);
}
*pac = p;
return 0;
}
KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_pac_add_buffer(krb5_context context, krb5_pac p,
uint32_t type, const krb5_data *data)
{
krb5_error_code ret;
void *ptr;
size_t len, offset, header_end, old_end;
uint32_t i;
len = p->pac->numbuffers;
ptr = realloc(p->pac,
sizeof(*p->pac) + (sizeof(p->pac->buffers[0]) * len));
if (ptr == NULL)
return krb5_enomem(context);
p->pac = ptr;
for (i = 0; i < len; i++)
p->pac->buffers[i].offset_lo += PAC_INFO_BUFFER_SIZE;
offset = p->data.length + PAC_INFO_BUFFER_SIZE;
p->pac->buffers[len].type = type;
p->pac->buffers[len].buffersize = data->length;
p->pac->buffers[len].offset_lo = offset;
p->pac->buffers[len].offset_hi = 0;
old_end = p->data.length;
len = p->data.length + data->length + PAC_INFO_BUFFER_SIZE;
if (len < p->data.length) {
krb5_set_error_message(context, EINVAL, "integer overrun");
return EINVAL;
}
/* align to PAC_ALIGNMENT */
len = ((len + PAC_ALIGNMENT - 1) / PAC_ALIGNMENT) * PAC_ALIGNMENT;
ret = krb5_data_realloc(&p->data, len);
if (ret) {
krb5_set_error_message(context, ret, N_("malloc: out of memory", ""));
return ret;
}
/*
* make place for new PAC INFO BUFFER header
*/
header_end = PACTYPE_SIZE + (PAC_INFO_BUFFER_SIZE * p->pac->numbuffers);
memmove((unsigned char *)p->data.data + header_end + PAC_INFO_BUFFER_SIZE,
(unsigned char *)p->data.data + header_end ,
old_end - header_end);
memset((unsigned char *)p->data.data + header_end, 0, PAC_INFO_BUFFER_SIZE);
/*
* copy in new data part
*/
memcpy((unsigned char *)p->data.data + offset,
data->data, data->length);
memset((unsigned char *)p->data.data + offset + data->length,
0, p->data.length - offset - data->length);
p->pac->numbuffers += 1;
return 0;
}
/**
* Get the PAC buffer of specific type from the pac.
*
* @param context Kerberos 5 context.
* @param p the pac structure returned by krb5_pac_parse().
* @param type type of buffer to get
* @param data return data, free with krb5_data_free().
*
* @return Returns 0 to indicate success. Otherwise an kerberos et
* error code is returned, see krb5_get_error_message().
*
* @ingroup krb5_pac
*/
KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_pac_get_buffer(krb5_context context, krb5_pac p,
uint32_t type, krb5_data *data)
{
krb5_error_code ret;
uint32_t i;
for (i = 0; i < p->pac->numbuffers; i++) {
const size_t len = p->pac->buffers[i].buffersize;
const size_t offset = p->pac->buffers[i].offset_lo;
if (p->pac->buffers[i].type != type)
continue;
ret = krb5_data_copy(data, (unsigned char *)p->data.data + offset, len);
if (ret) {
krb5_set_error_message(context, ret, N_("malloc: out of memory", ""));
return ret;
}
return 0;
}
krb5_set_error_message(context, ENOENT, "No PAC buffer of type %lu was found",
(unsigned long)type);
return ENOENT;
}
/*
*
*/
KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_pac_get_types(krb5_context context,
krb5_pac p,
size_t *len,
uint32_t **types)
{
size_t i;
*types = calloc(p->pac->numbuffers, sizeof(**types));
if (*types == NULL) {
*len = 0;
return krb5_enomem(context);
}
for (i = 0; i < p->pac->numbuffers; i++)
(*types)[i] = p->pac->buffers[i].type;
*len = p->pac->numbuffers;
return 0;
}
/*
*
*/
KRB5_LIB_FUNCTION void KRB5_LIB_CALL
krb5_pac_free(krb5_context context, krb5_pac pac)
{
krb5_data_free(&pac->data);
free(pac->pac);
free(pac);
}
/*
*
*/
static krb5_error_code
verify_checksum(krb5_context context,
const struct PAC_INFO_BUFFER *sig,
const krb5_data *data,
void *ptr, size_t len,
const krb5_keyblock *key)
{
krb5_storage *sp = NULL;
uint32_t type;
krb5_error_code ret;
Checksum cksum;
memset(&cksum, 0, sizeof(cksum));
sp = krb5_storage_from_mem((char *)data->data + sig->offset_lo,
sig->buffersize);
if (sp == NULL)
return krb5_enomem(context);
krb5_storage_set_flags(sp, KRB5_STORAGE_BYTEORDER_LE);
CHECK(ret, krb5_ret_uint32(sp, &type), out);
cksum.cksumtype = type;
cksum.checksum.length =
sig->buffersize - krb5_storage_seek(sp, 0, SEEK_CUR);
cksum.checksum.data = malloc(cksum.checksum.length);
if (cksum.checksum.data == NULL) {
ret = krb5_enomem(context);
goto out;
}
ret = krb5_storage_read(sp, cksum.checksum.data, cksum.checksum.length);
if (ret != (int)cksum.checksum.length) {
ret = EINVAL;
krb5_set_error_message(context, ret, "PAC checksum missing checksum");
goto out;
}
if (!krb5_checksum_is_keyed(context, cksum.cksumtype)) {
ret = EINVAL;
krb5_set_error_message(context, ret, "Checksum type %d not keyed",
cksum.cksumtype);
goto out;
}
/* If the checksum is HMAC-MD5, the checksum type is not tied to
* the key type, instead the HMAC-MD5 checksum is applied blindly
* on whatever key is used for this connection, avoiding issues
* with unkeyed checksums on des-cbc-md5 and des-cbc-crc. See
* http://comments.gmane.org/gmane.comp.encryption.kerberos.devel/8743
* for the same issue in MIT, and
* http://blogs.msdn.com/b/openspecification/archive/2010/01/01/verifying-the-server-signature-in-kerberos-privilege-account-certificate.aspx
* for Microsoft's explaination */
if (cksum.cksumtype == CKSUMTYPE_HMAC_MD5) {
Checksum local_checksum;
memset(&local_checksum, 0, sizeof(local_checksum));
ret = HMAC_MD5_any_checksum(context, key, ptr, len,
KRB5_KU_OTHER_CKSUM, &local_checksum);
if (ret != 0 || krb5_data_ct_cmp(&local_checksum.checksum, &cksum.checksum) != 0) {
ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
krb5_set_error_message(context, ret,
N_("PAC integrity check failed for "
"hmac-md5 checksum", ""));
}
krb5_data_free(&local_checksum.checksum);
} else {
krb5_crypto crypto = NULL;
ret = krb5_crypto_init(context, key, 0, &crypto);
if (ret)
goto out;
ret = krb5_verify_checksum(context, crypto, KRB5_KU_OTHER_CKSUM,
ptr, len, &cksum);
krb5_crypto_destroy(context, crypto);
}
free(cksum.checksum.data);
krb5_storage_free(sp);
return ret;
out:
if (cksum.checksum.data)
free(cksum.checksum.data);
if (sp)
krb5_storage_free(sp);
return ret;
}
static krb5_error_code
create_checksum(krb5_context context,
const krb5_keyblock *key,
uint32_t cksumtype,
void *data, size_t datalen,
void *sig, size_t siglen)
{
krb5_crypto crypto = NULL;
krb5_error_code ret;
Checksum cksum;
/* If the checksum is HMAC-MD5, the checksum type is not tied to
* the key type, instead the HMAC-MD5 checksum is applied blindly
* on whatever key is used for this connection, avoiding issues
* with unkeyed checksums on des-cbc-md5 and des-cbc-crc. See
* http://comments.gmane.org/gmane.comp.encryption.kerberos.devel/8743
* for the same issue in MIT, and
* http://blogs.msdn.com/b/openspecification/archive/2010/01/01/verifying-the-server-signature-in-kerberos-privilege-account-certificate.aspx
* for Microsoft's explaination */
if (cksumtype == (uint32_t)CKSUMTYPE_HMAC_MD5) {
ret = HMAC_MD5_any_checksum(context, key, data, datalen,
KRB5_KU_OTHER_CKSUM, &cksum);
if (ret)
return ret;
} else {
ret = krb5_crypto_init(context, key, 0, &crypto);
if (ret)
return ret;
ret = krb5_create_checksum(context, crypto, KRB5_KU_OTHER_CKSUM, 0,
data, datalen, &cksum);
krb5_crypto_destroy(context, crypto);
if (ret)
return ret;
}
if (cksum.checksum.length != siglen) {
krb5_set_error_message(context, EINVAL, "pac checksum wrong length");
free_Checksum(&cksum);
return EINVAL;
}
memcpy(sig, cksum.checksum.data, siglen);
free_Checksum(&cksum);
return 0;
}
/*
*
*/
#define NTTIME_EPOCH 0x019DB1DED53E8000LL
static uint64_t
unix2nttime(time_t unix_time)
{
long long wt;
wt = unix_time * (uint64_t)10000000 + (uint64_t)NTTIME_EPOCH;
return wt;
}
static krb5_error_code
verify_logonname(krb5_context context,
const struct PAC_INFO_BUFFER *logon_name,
const krb5_data *data,
time_t authtime,
krb5_const_principal principal)
{
krb5_error_code ret;
uint32_t time1, time2;
krb5_storage *sp;
uint16_t len;
char *s = NULL;
char *principal_string = NULL;
char *logon_string = NULL;
sp = krb5_storage_from_readonly_mem((const char *)data->data + logon_name->offset_lo,
logon_name->buffersize);
if (sp == NULL)
return krb5_enomem(context);
krb5_storage_set_flags(sp, KRB5_STORAGE_BYTEORDER_LE);
CHECK(ret, krb5_ret_uint32(sp, &time1), out);
CHECK(ret, krb5_ret_uint32(sp, &time2), out);
{
uint64_t t1, t2;
t1 = unix2nttime(authtime);
t2 = ((uint64_t)time2 << 32) | time1;
/*
* When neither the ticket nor the PAC set an explicit authtime,
* both times are zero, but relative to different time scales.
* So we must compare "not set" values without converting to a
* common time reference.
*/
if (t1 != t2 && (t2 != 0 && authtime != 0)) {
krb5_storage_free(sp);
krb5_set_error_message(context, EINVAL, "PAC timestamp mismatch");
return EINVAL;
}
}
CHECK(ret, krb5_ret_uint16(sp, &len), out);
if (len == 0) {
krb5_storage_free(sp);
krb5_set_error_message(context, EINVAL, "PAC logon name length missing");
return EINVAL;
}
s = malloc(len);
if (s == NULL) {
krb5_storage_free(sp);
return krb5_enomem(context);
}
ret = krb5_storage_read(sp, s, len);
if (ret != len) {
krb5_storage_free(sp);
krb5_set_error_message(context, EINVAL, "Failed to read PAC logon name");
return EINVAL;
}
krb5_storage_free(sp);
{
size_t ucs2len = len / 2;
uint16_t *ucs2;
size_t u8len;
unsigned int flags = WIND_RW_LE;
ucs2 = malloc(sizeof(ucs2[0]) * ucs2len);
if (ucs2 == NULL)
return krb5_enomem(context);
ret = wind_ucs2read(s, len, &flags, ucs2, &ucs2len);
free(s);
if (ret) {
free(ucs2);
krb5_set_error_message(context, ret, "Failed to convert string to UCS-2");
return ret;
}
ret = wind_ucs2utf8_length(ucs2, ucs2len, &u8len);
if (ret) {
free(ucs2);
krb5_set_error_message(context, ret, "Failed to count length of UCS-2 string");
return ret;
}
u8len += 1; /* Add space for NUL */
logon_string = malloc(u8len);
if (logon_string == NULL) {
free(ucs2);
return krb5_enomem(context);
}
ret = wind_ucs2utf8(ucs2, ucs2len, logon_string, &u8len);
free(ucs2);
if (ret) {
free(logon_string);
krb5_set_error_message(context, ret, "Failed to convert to UTF-8");
return ret;
}
}
ret = krb5_unparse_name_flags(context, principal,
KRB5_PRINCIPAL_UNPARSE_NO_REALM |
KRB5_PRINCIPAL_UNPARSE_DISPLAY,
&principal_string);
if (ret) {
free(logon_string);
return ret;
}
ret = strcmp(logon_string, principal_string);
if (ret != 0) {
ret = EINVAL;
krb5_set_error_message(context, ret, "PAC logon name [%s] mismatch principal name [%s]",
logon_string, principal_string);
}
free(logon_string);
free(principal_string);
return ret;
out:
return ret;
}
/*
*
*/
static krb5_error_code
build_logon_name(krb5_context context,
time_t authtime,
krb5_const_principal principal,
krb5_data *logon)
{
krb5_error_code ret;
krb5_storage *sp;
uint64_t t;
char *s, *s2;
size_t s2_len;
t = unix2nttime(authtime);
krb5_data_zero(logon);
sp = krb5_storage_emem();
if (sp == NULL)
return krb5_enomem(context);
krb5_storage_set_flags(sp, KRB5_STORAGE_BYTEORDER_LE);
CHECK(ret, krb5_store_uint32(sp, t & 0xffffffff), out);
CHECK(ret, krb5_store_uint32(sp, t >> 32), out);
ret = krb5_unparse_name_flags(context, principal,
KRB5_PRINCIPAL_UNPARSE_NO_REALM |
KRB5_PRINCIPAL_UNPARSE_DISPLAY,
&s);
if (ret)
goto out;
{
size_t ucs2_len;
uint16_t *ucs2;
unsigned int flags;
ret = wind_utf8ucs2_length(s, &ucs2_len);
if (ret) {
krb5_set_error_message(context, ret, "Principal %s is not valid UTF-8", s);
free(s);
return ret;
}
ucs2 = malloc(sizeof(ucs2[0]) * ucs2_len);
if (ucs2 == NULL) {
free(s);
return krb5_enomem(context);
}
ret = wind_utf8ucs2(s, ucs2, &ucs2_len);
if (ret) {
free(ucs2);
krb5_set_error_message(context, ret, "Principal %s is not valid UTF-8", s);
free(s);
return ret;
} else
free(s);
s2_len = (ucs2_len + 1) * 2;
s2 = malloc(s2_len);
if (s2 == NULL) {
free(ucs2);
return krb5_enomem(context);
}
flags = WIND_RW_LE;
ret = wind_ucs2write(ucs2, ucs2_len,
&flags, s2, &s2_len);
free(ucs2);
if (ret) {
free(s2);
krb5_set_error_message(context, ret, "Failed to write to UCS-2 buffer");
return ret;
}
/*
* we do not want zero termination
*/
s2_len = ucs2_len * 2;
}
CHECK(ret, krb5_store_uint16(sp, s2_len), out);
ret = krb5_storage_write(sp, s2, s2_len);
free(s2);
if (ret != (int)s2_len) {
ret = krb5_enomem(context);
goto out;
}
ret = krb5_storage_to_data(sp, logon);
if (ret)
goto out;
krb5_storage_free(sp);
return 0;
out:
krb5_storage_free(sp);
return ret;
}
/**
* Verify the PAC.
*
* @param context Kerberos 5 context.
* @param pac the pac structure returned by krb5_pac_parse().
* @param authtime The time of the ticket the PAC belongs to.
* @param principal the principal to verify.
* @param server The service key, most always be given.
* @param privsvr The KDC key, may be given.
* @return Returns 0 to indicate success. Otherwise an kerberos et
* error code is returned, see krb5_get_error_message().
*
* @ingroup krb5_pac
*/
KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_pac_verify(krb5_context context,
const krb5_pac pac,
time_t authtime,
krb5_const_principal principal,
const krb5_keyblock *server,
const krb5_keyblock *privsvr)
{
krb5_error_code ret;
if (pac->server_checksum == NULL) {
krb5_set_error_message(context, EINVAL, "PAC missing server checksum");
return EINVAL;
}
if (pac->privsvr_checksum == NULL) {
krb5_set_error_message(context, EINVAL, "PAC missing kdc checksum");
return EINVAL;
}
if (pac->logon_name == NULL) {
krb5_set_error_message(context, EINVAL, "PAC missing logon name");
return EINVAL;
}
ret = verify_logonname(context,
pac->logon_name,
&pac->data,
authtime,
principal);
if (ret)
return ret;
/*
* in the service case, clean out data option of the privsvr and
* server checksum before checking the checksum.
*/
{
krb5_data *copy;
if (pac->server_checksum->buffersize < 4 ||
pac->privsvr_checksum->buffersize < 4)
return EINVAL;
ret = krb5_copy_data(context, &pac->data, &copy);
if (ret)
return ret;
memset((char *)copy->data + pac->server_checksum->offset_lo + 4,
0,
pac->server_checksum->buffersize - 4);
memset((char *)copy->data + pac->privsvr_checksum->offset_lo + 4,
0,
pac->privsvr_checksum->buffersize - 4);
ret = verify_checksum(context,
pac->server_checksum,
&pac->data,
copy->data,
copy->length,
server);
krb5_free_data(context, copy);
if (ret)
return ret;
}
if (privsvr) {
/* The priv checksum covers the server checksum */
ret = verify_checksum(context,
pac->privsvr_checksum,
&pac->data,
(char *)pac->data.data
+ pac->server_checksum->offset_lo + 4,
pac->server_checksum->buffersize - 4,
privsvr);
if (ret)
return ret;
}
return 0;
}
/*
*
*/
static krb5_error_code
fill_zeros(krb5_context context, krb5_storage *sp, size_t len)
{
ssize_t sret;
size_t l;
while (len) {
l = len;
if (l > sizeof(zeros))
l = sizeof(zeros);
sret = krb5_storage_write(sp, zeros, l);
if (sret != l)
return krb5_enomem(context);
len -= sret;
}
return 0;
}
static krb5_error_code
pac_checksum(krb5_context context,
const krb5_keyblock *key,
uint32_t *cksumtype,
size_t *cksumsize)
{
krb5_cksumtype cktype;
krb5_error_code ret;
krb5_crypto crypto = NULL;
ret = krb5_crypto_init(context, key, 0, &crypto);
if (ret)
return ret;
ret = krb5_crypto_get_checksum_type(context, crypto, &cktype);
krb5_crypto_destroy(context, crypto);
if (ret)
return ret;
if (krb5_checksum_is_keyed(context, cktype) == FALSE) {
*cksumtype = CKSUMTYPE_HMAC_MD5;
*cksumsize = 16;
}
ret = krb5_checksumsize(context, cktype, cksumsize);
if (ret)
return ret;
*cksumtype = (uint32_t)cktype;
return 0;
}
KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
_krb5_pac_sign(krb5_context context,
krb5_pac p,
time_t authtime,
krb5_principal principal,
const krb5_keyblock *server_key,
const krb5_keyblock *priv_key,
krb5_data *data)
{
krb5_error_code ret;
krb5_storage *sp = NULL, *spdata = NULL;
uint32_t end;
size_t server_size, priv_size;
uint32_t server_offset = 0, priv_offset = 0;
uint32_t server_cksumtype = 0, priv_cksumtype = 0;
int num = 0;
size_t i;
krb5_data logon, d;
krb5_data_zero(&logon);
for (i = 0; i < p->pac->numbuffers; i++) {
if (p->pac->buffers[i].type == PAC_SERVER_CHECKSUM) {
if (p->server_checksum == NULL) {
p->server_checksum = &p->pac->buffers[i];
}
if (p->server_checksum != &p->pac->buffers[i]) {
ret = EINVAL;
krb5_set_error_message(context, ret,
N_("PAC have two server checksums", ""));
goto out;
}
} else if (p->pac->buffers[i].type == PAC_PRIVSVR_CHECKSUM) {
if (p->privsvr_checksum == NULL) {
p->privsvr_checksum = &p->pac->buffers[i];
}
if (p->privsvr_checksum != &p->pac->buffers[i]) {
ret = EINVAL;
krb5_set_error_message(context, ret,
N_("PAC have two KDC checksums", ""));
goto out;
}
} else if (p->pac->buffers[i].type == PAC_LOGON_NAME) {
if (p->logon_name == NULL) {
p->logon_name = &p->pac->buffers[i];
}
if (p->logon_name != &p->pac->buffers[i]) {
ret = EINVAL;
krb5_set_error_message(context, ret,
N_("PAC have two logon names", ""));
goto out;
}
}
}
if (p->logon_name == NULL)
num++;
if (p->server_checksum == NULL)
num++;
if (p->privsvr_checksum == NULL)
num++;
if (num) {
void *ptr;
ptr = realloc(p->pac, sizeof(*p->pac) + (sizeof(p->pac->buffers[0]) * (p->pac->numbuffers + num - 1)));
if (ptr == NULL)
return krb5_enomem(context);
p->pac = ptr;
if (p->logon_name == NULL) {
p->logon_name = &p->pac->buffers[p->pac->numbuffers++];
memset(p->logon_name, 0, sizeof(*p->logon_name));
p->logon_name->type = PAC_LOGON_NAME;
}
if (p->server_checksum == NULL) {
p->server_checksum = &p->pac->buffers[p->pac->numbuffers++];
memset(p->server_checksum, 0, sizeof(*p->server_checksum));
p->server_checksum->type = PAC_SERVER_CHECKSUM;
}
if (p->privsvr_checksum == NULL) {
p->privsvr_checksum = &p->pac->buffers[p->pac->numbuffers++];
memset(p->privsvr_checksum, 0, sizeof(*p->privsvr_checksum));
p->privsvr_checksum->type = PAC_PRIVSVR_CHECKSUM;
}
}
/* Calculate LOGON NAME */
ret = build_logon_name(context, authtime, principal, &logon);
if (ret)
goto out;
/* Set lengths for checksum */
ret = pac_checksum(context, server_key, &server_cksumtype, &server_size);
if (ret)
goto out;
ret = pac_checksum(context, priv_key, &priv_cksumtype, &priv_size);
if (ret)
goto out;
/* Encode PAC */
sp = krb5_storage_emem();
if (sp == NULL)
return krb5_enomem(context);
krb5_storage_set_flags(sp, KRB5_STORAGE_BYTEORDER_LE);
spdata = krb5_storage_emem();
if (spdata == NULL) {
krb5_storage_free(sp);
return krb5_enomem(context);
}
krb5_storage_set_flags(spdata, KRB5_STORAGE_BYTEORDER_LE);
CHECK(ret, krb5_store_uint32(sp, p->pac->numbuffers), out);
CHECK(ret, krb5_store_uint32(sp, p->pac->version), out);
end = PACTYPE_SIZE + (PAC_INFO_BUFFER_SIZE * p->pac->numbuffers);
for (i = 0; i < p->pac->numbuffers; i++) {
uint32_t len;
size_t sret;
void *ptr = NULL;
/* store data */
if (p->pac->buffers[i].type == PAC_SERVER_CHECKSUM) {
len = server_size + 4;
server_offset = end + 4;
CHECK(ret, krb5_store_uint32(spdata, server_cksumtype), out);
CHECK(ret, fill_zeros(context, spdata, server_size), out);
} else if (p->pac->buffers[i].type == PAC_PRIVSVR_CHECKSUM) {
len = priv_size + 4;
priv_offset = end + 4;
CHECK(ret, krb5_store_uint32(spdata, priv_cksumtype), out);
CHECK(ret, fill_zeros(context, spdata, priv_size), out);
} else if (p->pac->buffers[i].type == PAC_LOGON_NAME) {
len = krb5_storage_write(spdata, logon.data, logon.length);
if (logon.length != len) {
ret = EINVAL;
goto out;
}
} else {
len = p->pac->buffers[i].buffersize;
ptr = (char *)p->data.data + p->pac->buffers[i].offset_lo;
sret = krb5_storage_write(spdata, ptr, len);
if (sret != len) {
ret = krb5_enomem(context);
goto out;
}
/* XXX if not aligned, fill_zeros */
}
/* write header */
CHECK(ret, krb5_store_uint32(sp, p->pac->buffers[i].type), out);
CHECK(ret, krb5_store_uint32(sp, len), out);
CHECK(ret, krb5_store_uint32(sp, end), out);
CHECK(ret, krb5_store_uint32(sp, 0), out);
/* advance data endpointer and align */
{
int32_t e;
end += len;
e = ((end + PAC_ALIGNMENT - 1) / PAC_ALIGNMENT) * PAC_ALIGNMENT;
if ((int32_t)end != e) {
CHECK(ret, fill_zeros(context, spdata, e - end), out);
}
end = e;
}
}
/* assert (server_offset != 0 && priv_offset != 0); */
/* export PAC */
ret = krb5_storage_to_data(spdata, &d);
if (ret) {
krb5_set_error_message(context, ret, N_("malloc: out of memory", ""));
goto out;
}
ret = krb5_storage_write(sp, d.data, d.length);
if (ret != (int)d.length) {
krb5_data_free(&d);
ret = krb5_enomem(context);
goto out;
}
krb5_data_free(&d);
ret = krb5_storage_to_data(sp, &d);
if (ret) {
ret = krb5_enomem(context);
goto out;
}
/* sign */
ret = create_checksum(context, server_key, server_cksumtype,
d.data, d.length,
(char *)d.data + server_offset, server_size);
if (ret) {
krb5_data_free(&d);
goto out;
}
ret = create_checksum(context, priv_key, priv_cksumtype,
(char *)d.data + server_offset, server_size,
(char *)d.data + priv_offset, priv_size);
if (ret) {
krb5_data_free(&d);
goto out;
}
/* done */
*data = d;
krb5_data_free(&logon);
krb5_storage_free(sp);
krb5_storage_free(spdata);
return 0;
out:
krb5_data_free(&logon);
if (sp)
krb5_storage_free(sp);
if (spdata)
krb5_storage_free(spdata);
return ret;
}
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