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heimdal/lib/hdb/common.c
Joseph Sutton f7bcd8665c hdb: Remove redundant assignment 
Found by Coverity (Samba CID 1544603).

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
2023-11-02 20:19:54 -05:00

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/*
* Copyright (c) 1997-2002 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 "hdb_locl.h"
int
hdb_principal2key(krb5_context context, krb5_const_principal p, krb5_data *key)
{
Principal new;
size_t len = 0;
int ret;
ret = copy_Principal(p, &new);
if(ret)
return ret;
new.name.name_type = 0;
ASN1_MALLOC_ENCODE(Principal, key->data, key->length, &new, &len, ret);
if (ret == 0 && key->length != len)
krb5_abortx(context, "internal asn.1 encoder error");
free_Principal(&new);
return ret;
}
int
hdb_key2principal(krb5_context context, krb5_data *key, krb5_principal p)
{
return decode_Principal(key->data, key->length, p, NULL);
}
int
hdb_entry2value(krb5_context context, const hdb_entry *ent, krb5_data *value)
{
size_t len = 0;
int ret;
ASN1_MALLOC_ENCODE(HDB_entry, value->data, value->length, ent, &len, ret);
if (ret == 0 && value->length != len)
krb5_abortx(context, "internal asn.1 encoder error");
return ret;
}
int
hdb_value2entry(krb5_context context, krb5_data *value, hdb_entry *ent)
{
return decode_HDB_entry(value->data, value->length, ent, NULL);
}
int
hdb_entry_alias2value(krb5_context context,
const hdb_entry_alias *alias,
krb5_data *value)
{
size_t len = 0;
int ret;
ASN1_MALLOC_ENCODE(HDB_entry_alias, value->data, value->length,
alias, &len, ret);
if (ret == 0 && value->length != len)
krb5_abortx(context, "internal asn.1 encoder error");
return ret;
}
int
hdb_value2entry_alias(krb5_context context, krb5_data *value,
hdb_entry_alias *ent)
{
return decode_HDB_entry_alias(value->data, value->length, ent, NULL);
}
/*
* Some old databases may not have stored the salt with each key, which will
* break clients when aliases or canonicalization are used. Generate a
* default salt based on the real principal name in the entry to handle
* this case.
*/
static krb5_error_code
add_default_salts(krb5_context context, HDB *db, hdb_entry *entry)
{
krb5_error_code ret;
size_t i;
krb5_salt pwsalt;
ret = krb5_get_pw_salt(context, entry->principal, &pwsalt);
if (ret)
return ret;
for (i = 0; i < entry->keys.len; i++) {
Key *key = &entry->keys.val[i];
if (key->salt != NULL ||
_krb5_enctype_requires_random_salt(context, key->key.keytype))
continue;
key->salt = calloc(1, sizeof(*key->salt));
if (key->salt == NULL) {
ret = krb5_enomem(context);
break;
}
key->salt->type = KRB5_PADATA_PW_SALT;
ret = krb5_data_copy(&key->salt->salt,
pwsalt.saltvalue.data,
pwsalt.saltvalue.length);
if (ret)
break;
}
krb5_free_salt(context, pwsalt);
return ret;
}
static krb5_error_code
fetch_entry_or_alias(krb5_context context,
HDB *db,
krb5_const_principal principal,
unsigned flags,
hdb_entry *entry)
{
HDB_EntryOrAlias eoa;
krb5_principal enterprise_principal = NULL;
krb5_data key, value;
krb5_error_code ret;
value.length = 0;
value.data = 0;
key = value;
if (principal->name.name_type == KRB5_NT_ENTERPRISE_PRINCIPAL) {
if (principal->name.name_string.len != 1) {
ret = KRB5_PARSE_MALFORMED;
krb5_set_error_message(context, ret, "malformed principal: "
"enterprise name with %d name components",
principal->name.name_string.len);
return ret;
}
ret = krb5_parse_name(context, principal->name.name_string.val[0],
&enterprise_principal);
if (ret)
return ret;
principal = enterprise_principal;
}
ret = hdb_principal2key(context, principal, &key);
if (ret == 0)
ret = db->hdb__get(context, db, key, &value);
if (ret == 0)
ret = decode_HDB_EntryOrAlias(value.data, value.length, &eoa, NULL);
if (ret == 0 && eoa.element == choice_HDB_EntryOrAlias_entry) {
*entry = eoa.u.entry;
entry->aliased = 0;
} else if (ret == 0 && eoa.element == choice_HDB_EntryOrAlias_alias) {
krb5_data_free(&key);
ret = hdb_principal2key(context, eoa.u.alias.principal, &key);
if (ret == 0) {
krb5_data_free(&value);
ret = db->hdb__get(context, db, key, &value);
}
if (ret == 0)
/* No alias chaining */
ret = hdb_value2entry(context, &value, entry);
krb5_free_principal(context, eoa.u.alias.principal);
entry->aliased = 1;
} else if (ret == 0)
ret = ENOTSUP;
if (ret == 0 && enterprise_principal) {
/*
* Whilst Windows does not canonicalize enterprise principal names if
* the canonicalize flag is unset, the original specification in
* draft-ietf-krb-wg-kerberos-referrals-03.txt says we should.
*/
entry->flags.force_canonicalize = 1;
}
#if 0
/* HDB_F_GET_ANY indicates request originated from KDC (not kadmin) */
if (ret == 0 && eoa.element == choice_HDB_EntryOrAlias_alias &&
(flags & (HDB_F_CANON|HDB_F_GET_ANY)) == 0) {
/* `principal' was alias but canon not req'd */
free_HDB_entry(entry);
ret = HDB_ERR_NOENTRY;
}
#endif
krb5_free_principal(context, enterprise_principal);
krb5_data_free(&value);
krb5_data_free(&key);
principal = enterprise_principal = NULL;
return ret;
}
/*
* We have only one type of aliases in our HDB entries, but we really need two:
* hard and soft.
*
* Hard aliases should be treated as if they were distinct principals with the
* same keys.
*
* Soft aliases should be treated as configuration to issue referrals, and they
* can only result in referrals to other realms.
*
* Rather than add a type of aliases, we'll use a convention where the form of
* the target of the alias indicates whether the alias is hard or soft.
*
* TODO We could also use an attribute of the aliased entry.
*/
static int
is_soft_alias_p(krb5_context context,
krb5_const_principal principal,
unsigned int flags,
hdb_entry *h)
{
/* Target is a WELLKNOWN/REFERRALS/TARGET/... -> soft alias */
if (krb5_principal_get_num_comp(context, h->principal) >= 3 &&
strcmp(krb5_principal_get_comp_string(context, h->principal, 0),
KRB5_WELLKNOWN_NAME) == 0 &&
strcmp(krb5_principal_get_comp_string(context, h->principal, 1),
"REFERRALS") == 0 &&
strcmp(krb5_principal_get_comp_string(context, h->principal, 2),
"TARGET") == 0)
return 1;
/*
* Pre-8.0 we had only soft aliases for a while, and one site used aliases
* of referrals-targetNN@TARGET-REALM.
*/
if (krb5_principal_get_num_comp(context, h->principal) == 1 &&
strncmp("referrals-target",
krb5_principal_get_comp_string(context, h->principal, 0),
sizeof("referrals-target") - 1) == 0)
return 1;
/* All other cases are hard aliases */
return 0;
}
krb5_error_code
_hdb_fetch_kvno(krb5_context context, HDB *db, krb5_const_principal principal,
unsigned flags, krb5_kvno kvno, hdb_entry *entry)
{
krb5_error_code ret;
int soft_aliased = 0;
int same_realm;
ret = fetch_entry_or_alias(context, db, principal, flags, entry);
if (ret)
return ret;
if ((flags & HDB_F_DECRYPT) && (flags & HDB_F_ALL_KVNOS)) {
/* Decrypt the current keys */
ret = hdb_unseal_keys(context, db, entry);
if (ret) {
hdb_free_entry(context, db, entry);
return ret;
}
/* Decrypt the key history too */
ret = hdb_unseal_keys_kvno(context, db, 0, flags, entry);
if (ret) {
hdb_free_entry(context, db, entry);
return ret;
}
} else if ((flags & HDB_F_DECRYPT)) {
if ((flags & HDB_F_KVNO_SPECIFIED) == 0 || kvno == entry->kvno) {
/* Decrypt the current keys */
ret = hdb_unseal_keys(context, db, entry);
if (ret) {
hdb_free_entry(context, db, entry);
return ret;
}
} else {
if ((flags & HDB_F_ALL_KVNOS))
kvno = 0;
/*
* Find and decrypt the keys from the history that we want,
* and swap them with the current keys
*/
ret = hdb_unseal_keys_kvno(context, db, kvno, flags, entry);
if (ret) {
hdb_free_entry(context, db, entry);
return ret;
}
}
}
if ((flags & HDB_F_FOR_AS_REQ) && (flags & HDB_F_GET_CLIENT)) {
/*
* Generate default salt for any principals missing one; note such
* principals could include those for which a random (non-password)
* key was generated, but given the salt will be ignored by a keytab
* client it doesn't hurt to include the default salt.
*/
ret = add_default_salts(context, db, entry);
if (ret) {
hdb_free_entry(context, db, entry);
return ret;
}
}
if (!entry->aliased)
return 0;
soft_aliased = is_soft_alias_p(context, principal, flags, entry);
/* Never return HDB_ERR_WRONG_REALM to kadm5 or other non-KDC callers */
if ((flags & HDB_F_ADMIN_DATA))
return 0;
same_realm = krb5_realm_compare(context, principal, entry->principal);
if (entry->aliased && !soft_aliased) {
/*
* This is a hard alias. We'll make the entry's name be the same as
* the alias.
*
* Except, we allow for disabling this for same-realm aliases, mainly
* for our tests.
*/
if (same_realm &&
krb5_config_get_bool_default(context, NULL, FALSE, "hdb",
"same_realm_aliases_are_soft", NULL))
return 0;
/* EPNs are always soft */
if (principal->name.name_type != KRB5_NT_ENTERPRISE_PRINCIPAL) {
krb5_free_principal(context, entry->principal);
ret = krb5_copy_principal(context, principal, &entry->principal);
if (ret) {
hdb_free_entry(context, db, entry);
return ret;
}
}
return 0;
}
/* Same realm -> not a referral, therefore this is a hard alias */
if (same_realm) {
if (soft_aliased) {
/* Soft alias to the same realm?! No. */
hdb_free_entry(context, db, entry);
return HDB_ERR_NOENTRY;
}
return 0;
}
/* Not same realm && not hard alias */
return HDB_ERR_WRONG_REALM;
}
static krb5_error_code
hdb_remove_aliases(krb5_context context, HDB *db, krb5_data *key)
{
const HDB_Ext_Aliases *aliases;
krb5_error_code code;
hdb_entry oldentry;
krb5_data value;
size_t i;
code = db->hdb__get(context, db, *key, &value);
if (code == HDB_ERR_NOENTRY)
return 0;
else if (code)
return code;
code = hdb_value2entry(context, &value, &oldentry);
krb5_data_free(&value);
if (code)
return code;
code = hdb_entry_get_aliases(&oldentry, &aliases);
if (code || aliases == NULL) {
free_HDB_entry(&oldentry);
return code;
}
for (i = 0; i < aliases->aliases.len; i++) {
krb5_data akey;
code = hdb_principal2key(context, &aliases->aliases.val[i], &akey);
if (code == 0) {
code = db->hdb__del(context, db, akey);
krb5_data_free(&akey);
if (code == HDB_ERR_NOENTRY)
code = 0;
}
if (code) {
free_HDB_entry(&oldentry);
return code;
}
}
free_HDB_entry(&oldentry);
return 0;
}
static krb5_error_code
hdb_add_aliases(krb5_context context, HDB *db,
unsigned flags, hdb_entry *entry)
{
const HDB_Ext_Aliases *aliases;
krb5_error_code code;
krb5_data key, value;
size_t i;
code = hdb_entry_get_aliases(entry, &aliases);
if (code || aliases == NULL)
return code;
for (i = 0; i < aliases->aliases.len; i++) {
hdb_entry_alias entryalias;
entryalias.principal = entry->principal;
code = hdb_entry_alias2value(context, &entryalias, &value);
if (code)
return code;
code = hdb_principal2key(context, &aliases->aliases.val[i], &key);
if (code == 0) {
code = db->hdb__put(context, db, flags, key, value);
krb5_data_free(&key);
if (code == HDB_ERR_EXISTS)
/*
* Assuming hdb_check_aliases() was called, this must be a
* duplicate in the alias list.
*/
code = 0;
}
krb5_data_free(&value);
if (code)
return code;
}
return 0;
}
/* Check if new aliases are already used for other entries */
static krb5_error_code
hdb_check_aliases(krb5_context context, HDB *db, hdb_entry *entry)
{
const HDB_Ext_Aliases *aliases = NULL;
HDB_EntryOrAlias eoa;
krb5_data akey, value;
size_t i;
int ret;
memset(&eoa, 0, sizeof(eoa));
krb5_data_zero(&value);
akey = value;
ret = hdb_entry_get_aliases(entry, &aliases);
for (i = 0; ret == 0 && aliases && i < aliases->aliases.len; i++) {
ret = hdb_principal2key(context, &aliases->aliases.val[i], &akey);
if (ret == 0)
ret = db->hdb__get(context, db, akey, &value);
if (ret == 0)
ret = decode_HDB_EntryOrAlias(value.data, value.length, &eoa, NULL);
if (ret == 0 && eoa.element != choice_HDB_EntryOrAlias_entry &&
eoa.element != choice_HDB_EntryOrAlias_alias)
ret = ENOTSUP;
if (ret == 0 && eoa.element == choice_HDB_EntryOrAlias_entry)
/* New alias names an existing non-alias entry in the HDB */
ret = HDB_ERR_EXISTS;
if (ret == 0 && eoa.element == choice_HDB_EntryOrAlias_alias &&
!krb5_principal_compare(context, eoa.u.alias.principal,
entry->principal))
/* New alias names an existing alias of a different entry */
ret = HDB_ERR_EXISTS;
if (ret == HDB_ERR_NOENTRY) /* from db->hdb__get */
/* New alias is a name that doesn't exist in the HDB */
ret = 0;
free_HDB_EntryOrAlias(&eoa);
krb5_data_free(&value);
krb5_data_free(&akey);
}
return ret;
}
/*
* Many HDB entries don't have `etypes' setup. Historically we use the
* enctypes of the selected keyset as the entry's supported enctypes, but that
* is problematic. By doing this at store time and, if need be, at fetch time,
* we can make sure to stop deriving supported etypes from keys in the long
* run. We also need kadm5/kadmin support for etypes. We'll use this function
* there to derive etypes when using a kadm5_principal_ent_t that lacks the new
* TL data for etypes.
*/
krb5_error_code
hdb_derive_etypes(krb5_context context, hdb_entry *e, HDB_Ext_KeySet *base_keys)
{
krb5_error_code ret = 0;
size_t i, k, netypes;
HDB_extension *ext;
if (!base_keys &&
(ext = hdb_find_extension(e, choice_HDB_extension_data_hist_keys)))
base_keys = &ext->data.u.hist_keys;
netypes = e->keys.len;
if (netypes == 0 && base_keys) {
/* There's no way that base_keys->val[i].keys.len == 0, but hey */
for (i = 0; netypes == 0 && i < base_keys->len; i++)
netypes = base_keys->val[i].keys.len;
}
if (netypes == 0)
return 0;
if (e->etypes != NULL) {
free(e->etypes->val);
e->etypes->len = 0;
e->etypes->val = 0;
} else if ((e->etypes = calloc(1, sizeof(e->etypes[0]))) == NULL) {
ret = krb5_enomem(context);
}
if (ret == 0 &&
(e->etypes->val = calloc(netypes, sizeof(e->etypes->val[0]))) == NULL)
ret = krb5_enomem(context);
if (ret) {
free(e->etypes);
e->etypes = 0;
return ret;
}
e->etypes->len = netypes;
for (i = 0; i < e->keys.len && i < netypes; i++)
e->etypes->val[i] = e->keys.val[i].key.keytype;
if (!base_keys || i)
return 0;
for (k = 0; i == 0 && k < base_keys->len; k++) {
if (!base_keys->val[k].keys.len)
continue;
for (; i < base_keys->val[k].keys.len; i++)
e->etypes->val[i] = base_keys->val[k].keys.val[i].key.keytype;
}
return 0;
}
krb5_error_code
_hdb_store(krb5_context context, HDB *db, unsigned flags, hdb_entry *entry)
{
krb5_data key, value;
int code;
if (entry->flags.do_not_store ||
entry->flags.force_canonicalize)
return HDB_ERR_MISUSE;
/* check if new aliases already is used */
code = hdb_check_aliases(context, db, entry);
if (code)
return code;
if ((flags & HDB_F_PRECHECK) && (flags & HDB_F_REPLACE))
return 0;
if ((flags & HDB_F_PRECHECK)) {
code = hdb_principal2key(context, entry->principal, &key);
if (code)
return code;
code = db->hdb__get(context, db, key, &value);
krb5_data_free(&key);
if (code == 0)
krb5_data_free(&value);
if (code == HDB_ERR_NOENTRY)
return 0;
return code ? code : HDB_ERR_EXISTS;
}
if ((entry->etypes == NULL || entry->etypes->len == 0) &&
(code = hdb_derive_etypes(context, entry, NULL)))
return code;
if (entry->generation == NULL) {
struct timeval t;
entry->generation = malloc(sizeof(*entry->generation));
if(entry->generation == NULL) {
krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
return ENOMEM;
}
gettimeofday(&t, NULL);
entry->generation->time = t.tv_sec;
entry->generation->usec = t.tv_usec;
entry->generation->gen = 0;
} else
entry->generation->gen++;
code = hdb_seal_keys(context, db, entry);
if (code)
return code;
code = hdb_principal2key(context, entry->principal, &key);
if (code)
return code;
/* remove aliases */
code = hdb_remove_aliases(context, db, &key);
if (code) {
krb5_data_free(&key);
return code;
}
code = hdb_entry2value(context, entry, &value);
if (code == 0)
code = db->hdb__put(context, db, flags & HDB_F_REPLACE, key, value);
krb5_data_free(&value);
krb5_data_free(&key);
if (code)
return code;
code = hdb_add_aliases(context, db, flags, entry);
return code;
}
krb5_error_code
_hdb_remove(krb5_context context, HDB *db,
unsigned flags, krb5_const_principal principal)
{
krb5_data key, value;
HDB_EntryOrAlias eoa;
int is_alias = -1;
int code;
/*
* We only allow deletion of entries by canonical name. To remove an
* alias use kadm5_modify_principal().
*
* We need to determine if this is an alias. We decode as a
* HDB_EntryOrAlias, which is expensive -- we could decode as a
* HDB_entry_alias instead and assume it's an entry if decoding fails...
*/
code = hdb_principal2key(context, principal, &key);
if (code == 0)
code = db->hdb__get(context, db, key, &value);
if (code == 0) {
code = decode_HDB_EntryOrAlias(value.data, value.length, &eoa, NULL);
krb5_data_free(&value);
}
if (code == 0) {
is_alias = eoa.element == choice_HDB_EntryOrAlias_entry ? 0 : 1;
free_HDB_EntryOrAlias(&eoa);
}
if ((flags & HDB_F_PRECHECK)) {
if (code == 0 && is_alias)
krb5_set_error_message(context, code = HDB_ERR_NOENTRY,
"Cannot delete alias of principal");
krb5_data_free(&key);
return code;
}
if (code == 0)
code = hdb_remove_aliases(context, db, &key);
if (code == 0)
code = db->hdb__del(context, db, key);
krb5_data_free(&key);
return code;
}
/* PRF+(K_base, pad, keylen(etype)) */
static krb5_error_code
derive_Key1(krb5_context context,
krb5_data *pad,
EncryptionKey *base,
krb5int32 etype,
EncryptionKey *nk)
{
krb5_error_code ret;
krb5_crypto crypto = NULL;
krb5_data out;
size_t len;
out.data = 0;
out.length = 0;
ret = krb5_enctype_keysize(context, base->keytype, &len);
if (ret == 0)
ret = krb5_crypto_init(context, base, 0, &crypto);
if (ret == 0)
ret = krb5_crypto_prfplus(context, crypto, pad, len, &out);
if (crypto)
krb5_crypto_destroy(context, crypto);
if (ret == 0)
ret = krb5_random_to_key(context, etype, out.data, out.length, nk);
krb5_data_free(&out);
return ret;
}
/* PRF+(PRF+(K_base, princ, keylen(etype)), kvno, keylen(etype)) */
/* XXX Make it PRF+(PRF+(K_base, princ, keylen(K_base.etype)), and lift it, kvno, keylen(etype)) */
static krb5_error_code
derive_Key(krb5_context context,
const char *princ,
krb5uint32 kvno,
EncryptionKey *base,
krb5int32 etype,
Key *nk)
{
krb5_error_code ret = 0;
EncryptionKey intermediate;
krb5_data pad;
nk->salt = NULL;
nk->mkvno = NULL;
nk->key.keytype = 0;
nk->key.keyvalue.data = 0;
nk->key.keyvalue.length = 0;
intermediate.keytype = 0;
intermediate.keyvalue.data = 0;
intermediate.keyvalue.length = 0;
if (princ) {
/* Derive intermediate key for the given principal */
/* XXX Lift to optimize? */
pad.data = (void *)(uintptr_t)princ;
pad.length = strlen(princ);
ret = derive_Key1(context, &pad, base, etype, &intermediate);
if (ret == 0)
base = &intermediate;
} /* else `base' is already an intermediate key for the desired princ */
/* Derive final key for `kvno' from intermediate key */
kvno = htonl(kvno);
pad.data = &kvno;
pad.length = sizeof(kvno);
if (ret == 0)
ret = derive_Key1(context, &pad, base, etype, &nk->key);
free_EncryptionKey(&intermediate);
return ret;
}
/*
* PRF+(PRF+(K_base, princ, keylen(etype)), kvno, keylen(etype)) for one
* enctype.
*/
static krb5_error_code
derive_Keys(krb5_context context,
const char *princ,
krb5uint32 kvno,
krb5int32 etype,
const Keys *base,
Keys *dk)
{
krb5_error_code ret = 0;
size_t i;
Key nk;
dk->len = 0;
dk->val = 0;
/*
* The enctypes of the base keys is the list of enctypes to derive keys
* for. Still, we derive all keys from the first base key.
*/
for (i = 0; ret == 0 && i < base->len; i++) {
if (etype != KRB5_ENCTYPE_NULL && etype != base->val[i].key.keytype)
continue;
ret = derive_Key(context, princ, kvno, &base->val[0].key,
base->val[i].key.keytype, &nk);
if (ret)
break;
ret = add_Keys(dk, &nk);
free_Key(&nk);
/*
* FIXME We need to finish kdc/kadm5/kadmin support for the `etypes' so
* we can reduce the number of keys in keytabs to just those in current
* use and only of *one* enctype.
*
* What we could do is derive *one* key and for the others output a
* one-byte key of the intended enctype (which will never work).
*
* We'll never need any keys but the first one...
*/
}
if (ret)
free_Keys(dk);
return ret;
}
/* Helper for derive_keys_for_kr() */
static krb5_error_code
derive_keyset(krb5_context context,
const Keys *base_keys,
const char *princ,
krb5int32 etype,
krb5uint32 kvno,
KerberosTime set_time, /* "now" */
hdb_keyset *dks)
{
dks->kvno = kvno;
dks->keys.val = 0;
dks->set_time = malloc(sizeof(*(dks->set_time)));
if (dks->set_time == NULL)
return krb5_enomem(context);
*dks->set_time = set_time;
return derive_Keys(context, princ, kvno, etype, base_keys, &dks->keys);
}
/* Possibly derive and install in `h' a keyset identified by `t' */
static krb5_error_code
derive_keys_for_kr(krb5_context context,
hdb_entry *h,
HDB_Ext_KeySet *base_keys,
int is_current_keyset,
int rotation_period_offset,
const char *princ,
krb5int32 etype,
krb5uint32 kvno_wanted,
KerberosTime t,
struct KeyRotation *krp)
{
krb5_error_code ret;
hdb_keyset dks;
KerberosTime set_time, n;
krb5uint32 kvno;
size_t i;
if (rotation_period_offset < -1 || rotation_period_offset > 1)
return EINVAL; /* wat */
/*
* Compute `kvno' and `set_time' given `t' and `krp'.
*
* There be signed 32-bit time_t dragons here.
*
* (t - krp->epoch < 0) is better than (krp->epoch < t), making us more
* tolerant of signed 32-bit time_t here near 2038. Of course, we have
* signed 32-bit time_t dragons elsewhere.
*
* We don't need to check for n == 0 && rotation_period_offset < 0 because
* only derive_keys_for_current_kr() calls us with non-zero rotation period
* offsets, and it will never call us in that case.
*/
if (t - krp->epoch < 0)
return 0; /* This KR is not relevant yet */
n = (t - krp->epoch) / krp->period;
n += rotation_period_offset;
set_time = krp->epoch + krp->period * n;
kvno = krp->base_kvno + n;
/*
* Since this principal is virtual, or has virtual keys, we're going to
* derive a "password expiration time" for it in order to help httpkadmind
* and other tools figure out when to request keys again.
*
* The kadm5 representation of principals does not include the set_time of
* keys/keysets, so we can't have httpkadmind derive a Cache-Control from
* that without adding yet another "TL data". Since adding TL data is a
* huge pain, we'll just use the `pw_end' field of `HDB_entry' to
* communicate when this principal's keys will change next.
*/
if (h->pw_end[0] == 0) {
KerberosTime used = (t - krp->epoch) % krp->period;
KerberosTime left = krp->period - used;
/*
* If `h->pw_end[0]' == 0 then this must be the current period of the
* current KR we're deriving keys for. See upstairs.
*
* If there's more than a quarter of this time period left, then we'll
* set `h->pw_end[0]' to one quarter before the end of this time
* period. Else we'll set it to 1/4 after (we'll be including the next
* set of derived keys, so there's no harm in waiting that long to
* refetch).
*/
if (left > krp->period >> 2)
h->pw_end[0] = set_time + krp->period - (krp->period >> 2);
else
h->pw_end[0] = set_time + krp->period + (krp->period >> 2);
}
/*
* Do not waste cycles computing keys not wanted or needed.
* A past kvno is too old if its set_time + rotation period is in the past
* by more than half a rotation period, since then no service ticket
* encrypted with keys of that kvno can still be extant.
*
* A future kvno is not coming up soon enough if we're more than a quarter
* of the rotation period away from it.
*
* Recall: the assumption for virtually-keyed principals is that services
* fetch their future keys frequently enough that they'll never miss having
* the keys they need.
*/
if (!is_current_keyset || rotation_period_offset != 0) {
if ((kvno_wanted && kvno != kvno_wanted) ||
t - (set_time + krp->period + (krp->period >> 1)) > 0 ||
(set_time - t > 0 && (set_time - t) > (krp->period >> 2)))
return 0;
}
for (i = 0; i < base_keys->len; i++) {
if (base_keys->val[i].kvno == krp->base_key_kvno)
break;
}
if (i == base_keys->len) {
/* Base key not found! */
if (kvno_wanted || is_current_keyset) {
krb5_set_error_message(context, ret = HDB_ERR_KVNO_NOT_FOUND,
"Base key version %u not found for %s",
krp->base_key_kvno, princ);
return ret;
}
return 0;
}
ret = derive_keyset(context, &base_keys->val[i].keys, princ, etype, kvno,
set_time, &dks);
if (ret == 0)
ret = hdb_install_keyset(context, h, is_current_keyset, &dks);
free_HDB_keyset(&dks);
return ret;
}
/* Derive and install current keys, and possibly preceding or next keys */
static krb5_error_code
derive_keys_for_current_kr(krb5_context context,
hdb_entry *h,
HDB_Ext_KeySet *base_keys,
const char *princ,
unsigned int flags,
krb5int32 etype,
krb5uint32 kvno_wanted,
KerberosTime t,
struct KeyRotation *krp,
KerberosTime future_epoch)
{
krb5_error_code ret;
/* derive_keys_for_kr() for current kvno and install as the current keys */
ret = derive_keys_for_kr(context, h, base_keys, 1, 0, princ, etype,
kvno_wanted, t, krp);
if (!(flags & HDB_F_ALL_KVNOS))
return ret;
/* */
/*
* derive_keys_for_kr() for prev kvno if still needed -- it can only be
* needed if the prev kvno's start time is within this KR's epoch.
*
* Note that derive_keys_for_kr() can return without doing anything if this
* is isn't the current keyset. So these conditions need not be
* sufficiently narrow.
*/
if (ret == 0 && t - krp->epoch >= krp->period)
ret = derive_keys_for_kr(context, h, base_keys, 0, -1, princ, etype,
kvno_wanted, t, krp);
/*
* derive_keys_for_kr() for next kvno if near enough, but only if it
* doesn't start after the next KR's epoch.
*/
if (future_epoch &&
t - krp->epoch >= 0 /* We know! Hint to the compiler */) {
KerberosTime next_kvno_start, n;
n = (t - krp->epoch) / krp->period;
next_kvno_start = krp->epoch + krp->period * (n + 1);
if (future_epoch - next_kvno_start <= 0)
return ret;
}
if (ret == 0)
ret = derive_keys_for_kr(context, h, base_keys, 0, 1, princ, etype,
kvno_wanted, t, krp);
return ret;
}
/*
* Derive and install all keysets in `h' that `princ' needs at time `now'.
*
* This mutates the entry `h' to
*
* a) not have base keys,
* b) have keys derived from the base keys according to
* c) the key rotation periods for the base principal (possibly the same
* principal if it's a concrete principal with virtual keys), and the
* requested time, enctype, and kvno (all of which are optional, with zero
* implying some default).
*
* Arguments:
*
* - `flags' is the flags passed to `hdb_fetch_kvno()'
* - `princ' is the name of the principal we'll end up with in `entry'
* - `h_is_namespace' indicates whether `h' is for a namespace or a concrete
* principal (that might nonetheless have virtual/derived keys)
* - `t' is the time such that the derived keys are for kvnos needed at `t'
* - `etype' indicates what enctype to derive keys for (0 for all enctypes in
* `entry->etypes')
* - `kvno' requests a particular kvno, or all if zero
*
* The caller doesn't know if the principal needs key derivation -- we make
* that determination in this function.
*
* Note that this function is fully deterministic for any given set of
* arguments and HDB contents.
*
* Definitions:
*
* - A keyset is a set of keys for a single kvno.
* - A keyset is relevant IFF:
* - it is the keyset for a time period identified by `t' in a
* corresponding KR
* - it is a keyset for a past time period for which there may be extant,
* not-yet-expired tickets that a service may need to decrypt
* - it is a keyset for an upcoming time period that a service will need to
* fetch before that time period becomes current, that way the service
* can have keytab entries for those keys in time for when the KDC starts
* encrypting service tickets to those keys
*
* This function derives the keyset(s) for the current KR first. The idea is
* to optimize the order of resulting keytabs so that the most likely keys to
* be used come first.
*
* Invariants:
*
* - KR metadata is sane because sanity is checked for when storing HDB
* entries
* - KRs are sorted by epoch in descending order; KR #0's epoch is the most
* recent
* - KR periods are non-zero (we divide by period)
* - kvnos are numerically ordered and correspond to time periods
* - within each KR, the kvnos for larger times are larger than (or equal
* to) the kvnos of earlier times
* - at KR boundaries, the first kvno of the newer boundary is larger than
* the kvno of the last time period of the previous KR
* - the time `t' must fall into exactly one KR period
* - the time `t' must fall into exactly one period within a KR period
* - at most two kvnos will be relevant from the KR that `t' falls into
* (the current kvno for `t', and possibly either the preceding, or the
* next)
* - at most one kvno from non-current KRs will be derived: possibly one for a
* preceding KR, and possibly one from an upcoming KR
*
* There can be:
*
* - no KR extension (not a namespace principal, and no virtual keys)
* - 1, 2, or 3 KRs (see above)
* - the newest KR may have the `deleted' flag, meaning "does not exist after
* this epoch"
*
* Note that the last time period in any older KR can be partial.
*
* Timeline diagram:
*
* .......|--+--+...+--|---+---+---+...+--|----+...
* T20 T10 T11 RT12 T1n T01
* ^ ^ ^ ^ ^ ^ ^ T00
* | | | T22 T2n | | ^
* ^ | T21 | | |
* princ | | epoch of | epoch of
* did | | middle KR | newest epoch
* not | | |
* exist! | start of Note that T1n
* | second kvno is shown as shorter
* | in 1st epoch than preceding periods
* |
* ^
* first KR's
* epoch, and start
* of its first kvno
*
* Tmn == the start of the Mth KR's Nth time period.
* (higher M -> older KR; lower M -> newer KR)
* (N is the reverse: lower N -> older time period in KR)
* T20 == start of oldest KR -- no keys before this time will be derived.
* T2n == last time period in oldest KR
* T10 == start of middle KR
* T1n == last time period in middle KR
* T00 == start of newest KR
* T0n == current time period in newest KR for wall clock time
*/
static krb5_error_code
derive_keys(krb5_context context,
unsigned flags,
krb5_const_principal princ,
int h_is_namespace,
krb5_timestamp t,
krb5int32 etype,
krb5uint32 kvno,
hdb_entry *h)
{
HDB_Ext_KeyRotation kr;
HDB_Ext_KeySet base_keys;
krb5_error_code ret = 0;
size_t current_kr, future_kr, past_kr, i;
char *p = NULL;
int valid = 1;
if (!h_is_namespace && !h->flags.virtual_keys)
return 0;
h->flags.virtual = 1;
kr.len = 0;
kr.val = 0;
if (ret == 0) {
const HDB_Ext_KeyRotation *ckr;
/* Installing keys invalidates `ckr', so we copy it */
ret = hdb_entry_get_key_rotation(context, h, &ckr);
if (!ckr)
return ret;
if (ret == 0)
ret = copy_HDB_Ext_KeyRotation(ckr, &kr);
}
/* Get the base keys from the entry, and remove them */
base_keys.val = 0;
base_keys.len = 0;
if (ret == 0)
ret = _hdb_remove_base_keys(context, h, &base_keys, &kr);
/* Make sure we have h->etypes */
if (ret == 0 && !h->etypes)
ret = hdb_derive_etypes(context, h, &base_keys);
/* Keys not desired? Don't derive them! */
if (ret || !(flags & HDB_F_DECRYPT)) {
free_HDB_Ext_KeyRotation(&kr);
free_HDB_Ext_KeySet(&base_keys);
return ret;
}
/* The principal name will be used in key derivation and error messages */
if (ret == 0)
ret = krb5_unparse_name(context, princ, &p);
/* Sanity check key rotations, determine current & last kr */
if (ret == 0 && kr.len < 1)
krb5_set_error_message(context, ret = HDB_ERR_NOENTRY,
"no key rotation periods for %s", p);
if (ret == 0)
current_kr = future_kr = past_kr = kr.len;
else
current_kr = future_kr = past_kr = 1;
/*
* Identify a current, next, and previous KRs if there are any.
*
* There can be up to three KRs, ordered by epoch, descending, making up a
* timeline like:
*
* ...|---------|--------|------>
* ^ | | |
* | | | |
* | | | Newest KR (kr.val[0])
* | | Middle KR (kr.val[1])
* | Oldest (last) KR (kr.val[2])
* |
* Before the begging of time for this namespace
*
* We step through these from future towards past looking for the best
* future, current, and past KRs. The best current KR is one that has its
* epoch nearest to `t' but in the past of `t'.
*
* We validate KRs before storing HDB entries with the KR extension, so we
* can assume they are valid here. However, we do some validity checking,
* and if they're not valid, we pick the best current KR and ignore the
* others.
*
* In principle there cannot be two future KRs, but this function is
* deterministic and takes a time value, so it should not enforce this just
* so we can test. Enforcement of such rules should be done at store time.
*/
for (i = 0; ret == 0 && i < kr.len; i++) {
/* Minimal validation: order and period */
if (i && kr.val[i - 1].epoch - kr.val[i].epoch <= 0) {
future_kr = past_kr = kr.len;
valid = 0;
}
if (!kr.val[i].period) {
future_kr = past_kr = kr.len;
valid = 0;
continue;
}
if (t - kr.val[i].epoch >= 0) {
/*
* `t' is in the future of this KR's epoch, so it's a candidate for
* either current or past KR.
*/
if (current_kr == kr.len)
current_kr = i; /* First curr KR candidate; should be best */
else if (kr.val[current_kr].epoch - kr.val[i].epoch < 0)
current_kr = i; /* Invalid KRs, but better curr KR cand. */
else if (valid && past_kr == kr.len)
past_kr = i;
} else if (valid) {
/* This KR is in the future of `t', a candidate for next KR */
future_kr = i;
}
}
if (ret == 0 && current_kr == kr.len)
/* No current KR -> too soon */
krb5_set_error_message(context, ret = HDB_ERR_NOENTRY,
"Too soon for virtual principal to exist");
/* Check that the principal has not been marked deleted */
if (ret == 0 && current_kr < kr.len && kr.val[current_kr].flags.deleted)
krb5_set_error_message(context, ret = HDB_ERR_NOENTRY,
"virtual principal %s does not exist "
"because last key rotation period "
"marks deletion", p);
/* See `derive_keys_for_kr()' */
if (h->pw_end == NULL &&
(h->pw_end = calloc(1, sizeof(h->pw_end[0]))) == NULL)
ret = krb5_enomem(context);
/*
* Derive and set in `h' its current kvno and current keys.
*
* This will set h->kvno as well.
*
* This may set up to TWO keysets for the current key rotation period:
* - current keys (h->keys and h->kvno)
* - possibly one future
* OR
* possibly one past keyset in hist_keys for the current_kr
*/
if (ret == 0 && current_kr < kr.len)
ret = derive_keys_for_current_kr(context, h, &base_keys, p, flags,
etype, kvno, t, &kr.val[current_kr],
current_kr ? kr.val[0].epoch : 0);
/*
* Derive and set in `h' its future keys for next KR if it is soon to be
* current.
*
* We want to derive keys for the first kvno of the next (future) KR if
* it's sufficiently close to `t', meaning within 1 period of the current
* KR, but we want these keys to be available sooner, so 1.5 of the current
* period.
*/
if (ret == 0 && future_kr < kr.len && (flags & HDB_F_ALL_KVNOS))
ret = derive_keys_for_kr(context, h, &base_keys, 0, 0, p, etype, kvno,
kr.val[future_kr].epoch, &kr.val[future_kr]);
/*
* Derive and set in `h' its past keys for the previous KR if its last time
* period could still have extant, unexpired service tickets encrypted in
* its keys.
*/
if (ret == 0 && past_kr < kr.len && (flags & HDB_F_ALL_KVNOS))
ret = derive_keys_for_kr(context, h, &base_keys, 0, 0, p, etype, kvno,
kr.val[current_kr].epoch - 1, &kr.val[past_kr]);
/*
* Impose a bound on h->max_life so that [when the KDC is the caller]
* the KDC won't issue tickets longer lived than this.
*/
if (ret == 0 && !h->max_life &&
(h->max_life = calloc(1, sizeof(h->max_life[0]))) == NULL)
ret = krb5_enomem(context);
if (ret == 0 && *h->max_life > kr.val[current_kr].period >> 1)
*h->max_life = kr.val[current_kr].period >> 1;
if (ret == 0 && h->pw_end[0] == 0)
/* Shouldn't happen */
h->pw_end[0] = kr.val[current_kr].epoch +
kr.val[current_kr].period *
(1 + (t - kr.val[current_kr].epoch) / kr.val[current_kr].period);
free_HDB_Ext_KeyRotation(&kr);
free_HDB_Ext_KeySet(&base_keys);
free(p);
return ret;
}
/*
* Pick a best kvno for the given principal at the given time.
*
* Implements the [hdb] new_service_key_delay configuration parameter.
*
* In order for disparate keytab provisioning systems such as OSKT and our own
* kadmin ext_keytab and httpkadmind's get-keys to coexist, we need to be able
* to force keys set by the former to not become current keys until users of
* the latter have had a chance to fetch those keys into their keytabs. To do
* this we have to search the list of keys in the entry looking for the newest
* keys older than `now - db->new_service_key_delay'.
*
* The context is that OSKT's krb5_keytab is very happy to change keys in a way
* that requires all members of a cluster to rekey together. If one also
* wishes to have cluster members that opt out of this and just fetch current,
* past, and future keys periodically, then the keys set by OSKT must not come
* into effect until all the opt-out members have had a chance to fetch the new
* keys.
*
* The assumption is that services will fetch new keys periodically, say, every
* four hours. Then one can set `[hdb] new_service_key_delay = 8h' in the
* configuration and new keys set by OSKT will not be used until 8h after they
* are set.
*
* Naturally, this applies only to concrete principals with concrete keys.
*/
static krb5_error_code
pick_kvno(krb5_context context,
HDB *db,
unsigned flags,
krb5_timestamp now,
krb5uint32 kvno,
hdb_entry *h)
{
HDB_extension *ext;
HDB_Ext_KeySet keys;
time_t current = 0;
time_t best;
size_t i;
/*
* If we want a specific kvno, or if the caller doesn't want new keys
* delayed, or if there's no new-key delay configured, or we're not
* fetching for use as a service principal, then we're out.
*/
if (!(flags & HDB_F_DELAY_NEW_KEYS) || kvno || h->flags.virtual ||
h->flags.virtual_keys || db->new_service_key_delay <= 0)
return 0;
/* No history -> current keyset is the only one and therefore the best */
ext = hdb_find_extension(h, choice_HDB_extension_data_hist_keys);
if (!ext)
return 0;
/* Assume the current keyset is the best to start with */
(void) hdb_entry_get_pw_change_time(h, &current);
if (current == 0 && h->modified_by)
current = h->modified_by->time;
if (current == 0)
current = h->created_by.time;
/* Current keyset starts out as best */
best = current;
kvno = h->kvno;
/* Look for a better keyset in the history */
keys = ext->data.u.hist_keys;
for (i = 0; i < keys.len; i++) {
/* No set_time? Ignore. Too new? Ignore */
if (!keys.val[i].set_time ||
keys.val[i].set_time[0] + db->new_service_key_delay > now)
continue;
/*
* Ignore the keyset with kvno 1 when the entry has better kvnos
* because kadmin's `ank -r' command immediately changes the keys.
*/
if (kvno > 1 && keys.val[i].kvno == 1)
continue;
/*
* This keyset's set_time older than the previous best? Ignore.
* However, if the current best is the entry's current and that one
* is too new, then don't ignore this one.
*/
if (keys.val[i].set_time[0] < best &&
(best != current || current + db->new_service_key_delay < now))
continue;
/*
* If two good enough keysets have the same set_time, take the keyset
* with the highest kvno.
*/
if (keys.val[i].set_time[0] == best && keys.val[i].kvno <= kvno)
continue;
/*
* This keyset is clearly more current than the previous best keyset
* but still old enough to use for encrypting tickets with.
*/
best = keys.val[i].set_time[0];
kvno = keys.val[i].kvno;
}
return hdb_change_kvno(context, kvno, h);
}
/*
* Make a WELLKNOWN/HOSTBASED-NAMESPACE/${svc}/${hostname} or
* WELLKNOWN/HOSTBASED-NAMESPACE/${svc}/${hostname}/${domainname} principal
* object, with the service and hostname components take from `wanted', but if
* the service name is not in the list `db->virtual_hostbased_princ_svcs[]'
* then use "_" (wildcard) instead. This way we can have different attributes
* for different services in the same namespaces.
*
* For example, virtual hostbased service names for the "host" service might
* have ok-as-delegate set, but ones for the "HTTP" service might not.
*/
static krb5_error_code
make_namespace_princ(krb5_context context,
HDB *db,
krb5_const_principal wanted,
krb5_principal *namespace)
{
krb5_error_code ret = 0;
const char *realm = krb5_principal_get_realm(context, wanted);
const char *comp0 = krb5_principal_get_comp_string(context, wanted, 0);
const char *comp1 = krb5_principal_get_comp_string(context, wanted, 1);
const char *comp2 = krb5_principal_get_comp_string(context, wanted, 2);
char * const *svcs = db->virtual_hostbased_princ_svcs;
size_t i;
*namespace = NULL;
if (comp0 == NULL || comp1 == NULL)
return EINVAL;
if (strcmp(comp0, "krbtgt") == 0)
return 0;
for (i = 0; svcs && svcs[i]; i++) {
if (strcmp(comp0, svcs[i]) == 0) {
comp0 = svcs[i];
break;
}
}
if (!svcs || !svcs[i])
comp0 = "_";
/* First go around, need a namespace princ. Make it! */
ret = krb5_build_principal(context, namespace, strlen(realm),
realm, KRB5_WELLKNOWN_NAME,
HDB_WK_NAMESPACE, comp0, NULL);
if (ret == 0)
ret = krb5_principal_set_comp_string(context, *namespace, 3, comp1);
if (ret == 0 && comp2)
/* Support domain-based names */
ret = krb5_principal_set_comp_string(context, *namespace, 4, comp2);
/* Caller frees `*namespace' on error */
return ret;
}
static int
is_namespace_princ_p(krb5_context context,
krb5_const_principal princ)
{
return
krb5_principal_get_num_comp(context, princ) >= 4
&& strcmp(krb5_principal_get_comp_string(context, princ, 0),
KRB5_WELLKNOWN_NAME) == 0
&& strcmp(krb5_principal_get_comp_string(context, princ, 1),
HDB_WK_NAMESPACE) == 0;
}
/* See call site */
static krb5_error_code
rewrite_hostname(krb5_context context,
krb5_const_principal wanted_princ,
krb5_const_principal ns_princ,
krb5_const_principal found_ns_princ,
char **s)
{
const char *ns_host_part, *wanted_host_part, *found_host_part;
const char *p, *r;
size_t ns_host_part_len, wanted_host_part_len;
wanted_host_part = krb5_principal_get_comp_string(context, wanted_princ, 1);
wanted_host_part_len = strlen(wanted_host_part);
if (wanted_host_part_len > 256) {
krb5_set_error_message(context, HDB_ERR_NOENTRY,
"Aliases of host-based principals longer than "
"256 bytes not supported");
return HDB_ERR_NOENTRY;
}
ns_host_part = krb5_principal_get_comp_string(context, ns_princ, 3);
ns_host_part_len = strlen(ns_host_part);
/* Find `ns_host_part' as the tail of `wanted_host_part' */
for (r = p = strstr(wanted_host_part, ns_host_part);
r && strnlen(r, ns_host_part_len + 1) > ns_host_part_len;
p = (r = strstr(r, ns_host_part)) ? r : p)
;
if (!p || strnlen(p, ns_host_part_len + 1) != ns_host_part_len)
return HDB_ERR_NOENTRY; /* Can't happen */
if (p == wanted_host_part || p[-1] != '.')
return HDB_ERR_NOENTRY;
found_host_part =
krb5_principal_get_comp_string(context, found_ns_princ, 3);
return
asprintf(s, "%.*s%s", (int)(p - wanted_host_part), wanted_host_part,
found_host_part) < 0 ||
*s == NULL ? krb5_enomem(context) : 0;
}
/*
* Fix `h->principal' to match the desired `princ' in the namespace
* `nsprinc' (which is either the same as `h->principal' or an alias
* of it).
*/
static krb5_error_code
fix_princ_name(krb5_context context,
krb5_const_principal princ,
krb5_const_principal nsprinc,
hdb_entry *h)
{
krb5_error_code ret = 0;
char *s = NULL;
if (!nsprinc)
return 0;
if (krb5_principal_get_num_comp(context, princ) < 2)
return HDB_ERR_NOENTRY;
/* `nsprinc' must be a namespace principal */
if (krb5_principal_compare(context, nsprinc, h->principal)) {
/*
* `h' is the HDB entry for `nsprinc', and `nsprinc' is its canonical
* name.
*
* Set the entry's principal name to the desired name. The keys will
* be fixed next (upstairs, but don't forget to!).
*/
free_Principal(h->principal);
return copy_Principal(princ, h->principal);
}
if (!is_namespace_princ_p(context, h->principal)) {
/*
* The alias is a namespace, but the canonical name is not. WAT.
*
* Well, the KDC will just issue a referral anyways, so we can leave
* `h->principal' as is...
*
* Remove all of `h's keys just in case, and leave
* `h->principal' as-is.
*/
free_Keys(&h->keys);
(void) hdb_entry_clear_password(context, h);
return hdb_clear_extension(context, h,
choice_HDB_extension_data_hist_keys);
}
/*
* A namespace alias of a namespace entry.
*
* We'll want to rewrite the original principal accordingly.
*
* E.g., if the caller wanted host/foo.ns.test.h5l.se and we
* found WELLKNOWN/HOSTBASED-NAMESPACE/ns.test.h5l.se is an
* alias of WELLKNOWN/HOSTBASED-NAMESPACE/ns.example.org, then
* we'll want to treat host/foo.ns.test.h5l.se as an alias of
* host/foo.ns.example.org.
*/
if (krb5_principal_get_num_comp(context, h->principal) !=
2 + krb5_principal_get_num_comp(context, princ))
ret = HDB_ERR_NOENTRY; /* Only host-based services for now */
if (ret == 0)
ret = rewrite_hostname(context, princ, nsprinc, h->principal, &s);
if (ret == 0) {
krb5_free_principal(context, h->principal);
h->principal = NULL;
ret = krb5_make_principal(context, &h->principal,
krb5_principal_get_realm(context, princ),
krb5_principal_get_comp_string(context,
princ, 0),
s,
NULL);
}
free(s);
return ret;
}
/* Wrapper around db->hdb_fetch_kvno() that implements virtual princs/keys */
static krb5_error_code
fetch_it(krb5_context context,
HDB *db,
krb5_const_principal princ,
unsigned flags,
krb5_timestamp t,
krb5int32 etype,
krb5uint32 kvno,
hdb_entry *ent)
{
krb5_const_principal tmpprinc = princ;
krb5_principal nsprinc = NULL;
krb5_error_code ret = 0;
const char *comp0 = krb5_principal_get_comp_string(context, princ, 0);
const char *comp1 = krb5_principal_get_comp_string(context, princ, 1);
const char *tmp;
size_t mindots = db->virtual_hostbased_princ_ndots;
size_t maxdots = db->virtual_hostbased_princ_maxdots;
size_t hdots = 0;
char *host = NULL;
int do_search = 0;
if (!db->enable_virtual_hostbased_princs)
maxdots = mindots = 0;
if (db->enable_virtual_hostbased_princs && comp1 &&
strcmp("krbtgt", comp0) != 0 && strcmp(KRB5_WELLKNOWN_NAME, comp0) != 0) {
char *htmp;
if ((host = strdup(comp1)) == NULL)
return krb5_enomem(context);
/* Strip out any :port */
htmp = strchr(host, ':');
if (htmp) {
if (strchr(htmp + 1, ':')) {
/* Extra ':'s? No virtualization for you! */
free(host);
host = NULL;
} else {
*htmp = '\0';
}
}
/* Count dots in `host' */
for (hdots = 0, htmp = host; htmp && *htmp; htmp++)
if (*htmp == '.')
hdots++;
do_search = 1;
}
tmp = host ? host : comp1;
for (ret = HDB_ERR_NOENTRY; ret == HDB_ERR_NOENTRY; tmpprinc = nsprinc) {
krb5_error_code ret2 = 0;
/*
* We break out of this loop with ret == 0 only if we found the HDB
* entry we were looking for or the HDB entry for a matching namespace.
*
* Otherwise we break out with ret != 0, typically HDB_ERR_NOENTRY.
*
* First time through we lookup the principal as given.
*
* Next we lookup a namespace principal, stripping off hostname labels
* from the left until we find one or get tired of looking or run out
* of labels.
*/
ret = db->hdb_fetch_kvno(context, db, tmpprinc, flags, kvno, ent);
if (ret == 0 && nsprinc && ent->flags.invalid) {
free_HDB_entry(ent);
ret = HDB_ERR_NOENTRY;
}
if (ret != HDB_ERR_NOENTRY || hdots == 0 || hdots < mindots || !tmp ||
!do_search)
break;
/*
* Breadcrumb:
*
* - if we found a concrete principal, but it's been marked
* as now-virtual, then we must keep going
*
* But this will be coded in the future.
*
* Maybe we can take attributes from the concrete principal...
*/
/*
* The namespace's hostname will not have more labels than maxdots + 1.
* Thus we truncate immediately down to maxdots + 1 if we haven't yet.
*
* Example: with maxdots == 3,
* foo.bar.baz.app.blah.example -> baz.app.blah.example
*/
while (maxdots && hdots > maxdots && tmp) {
tmp = strchr(tmp, '.');
/* tmp != NULL because maxdots > 0; we check to quiet linters */
if (tmp == NULL) {
ret = HDB_ERR_NOENTRY;
goto out;
}
tmp++;
hdots--;
}
if (nsprinc == NULL)
/* First go around, need a namespace princ. Make it! */
ret2 = make_namespace_princ(context, db, tmpprinc, &nsprinc);
/* Update the hostname component of the namespace principal */
if (ret2 == 0)
ret2 = krb5_principal_set_comp_string(context, nsprinc, 3, tmp);
if (ret2)
ret = ret2;
if (tmp) {
/* Strip off left-most label for the next go-around */
if ((tmp = strchr(tmp, '.')))
tmp++;
hdots--;
} /* else we'll break out after the next db->hdb_fetch_kvno() call */
}
/*
* If unencrypted keys were requested, derive them. There may not be any
* key derivation to do, but that's decided in derive_keys().
*/
if (ret == 0 || ret == HDB_ERR_WRONG_REALM) {
krb5_error_code save_ret = ret;
/* Fix the principal name if namespaced */
ret = fix_princ_name(context, princ, nsprinc, ent);
/* Derive keys if namespaced or virtual */
if (ret == 0)
ret = derive_keys(context, flags, princ, !!nsprinc, t, etype, kvno,
ent);
/* Pick the best kvno for this principal at the given time */
if (ret == 0)
ret = pick_kvno(context, db, flags, t, kvno, ent);
if (ret == 0)
ret = save_ret;
}
out:
if (ret != 0 && ret != HDB_ERR_WRONG_REALM)
hdb_free_entry(context, db, ent);
krb5_free_principal(context, nsprinc);
free(host);
return ret;
}
/**
* Fetch a principal's HDB entry, possibly generating virtual keys from base
* keys according to strict key rotation schedules. If a time is given, other
* than HDB I/O, this function is pure, thus usable for testing.
*
* HDB writers should use `db->hdb_fetch_kvno()' to avoid materializing virtual
* principals.
*
* HDB readers should use this function rather than `db->hdb_fetch_kvno()'
* unless they only want to see concrete principals and not bother generating
* any virtual keys.
*
* @param context Context
* @param db HDB
* @param principal Principal name
* @param flags Fetch flags
* @param t For virtual keys, use this as the point in time (use zero to mean "now")
* @param etype Key enctype (use KRB5_ENCTYPE_NULL to mean "preferred")
* @param kvno Key version number (use zero to mean "current")
* @param h Output HDB entry
*
* @return Zero or HDB_ERR_WRONG_REALM on success, an error code otherwise.
*/
krb5_error_code
hdb_fetch_kvno(krb5_context context,
HDB *db,
krb5_const_principal principal,
unsigned int flags,
krb5_timestamp t,
krb5int32 etype,
krb5uint32 kvno,
hdb_entry *h)
{
krb5_error_code ret;
krb5_timestamp now;
krb5_timeofday(context, &now);
flags |= kvno ? HDB_F_KVNO_SPECIFIED : 0; /* XXX is this needed */
ret = fetch_it(context, db, principal, flags, t ? t : now, etype, kvno, h);
if (ret == 0 && t == 0 && h->flags.virtual &&
h->pw_end && h->pw_end[0] < now) {
/*
* This shouldn't happen!
*
* Do not allow h->pw_end[0] to be in the past for virtual principals
* outside testing. This is just to prevent the AS/TGS from failing.
*/
h->pw_end[0] = now + 3600;
}
if (ret == HDB_ERR_NOENTRY)
krb5_set_error_message(context, ret, "no such entry found in hdb");
return ret;
}
size_t ASN1CALL
length_hdb_keyset(HDB_keyset *data)
{
return length_HDB_keyset(data);
}
size_t ASN1CALL
length_hdb_entry(HDB_entry *data)
{
return length_HDB_entry(data);
}
size_t ASN1CALL
length_hdb_entry_alias(HDB_entry_alias *data)
{
return length_HDB_entry_alias(data);
}
void ASN1CALL
free_hdb_keyset(HDB_keyset *data)
{
free_HDB_keyset(data);
}
void ASN1CALL
free_hdb_entry(HDB_entry *data)
{
free_HDB_entry(data);
}
void ASN1CALL
free_hdb_entry_alias(HDB_entry_alias *data)
{
free_HDB_entry_alias(data);
}
size_t ASN1CALL
copy_hdb_keyset(const HDB_keyset *from, HDB_keyset *to)
{
return copy_HDB_keyset(from, to);
}
size_t ASN1CALL
copy_hdb_entry(const HDB_entry *from, HDB_entry *to)
{
return copy_HDB_entry(from, to);
}
size_t ASN1CALL
copy_hdb_entry_alias(const HDB_entry_alias *from, HDB_entry_alias *to)
{
return copy_HDB_entry_alias(from, to);
}
int ASN1CALL
decode_hdb_keyset(const unsigned char *p,
size_t len,
HDB_keyset *data,
size_t *size)
{
return decode_HDB_keyset(p, len, data, size);
}
int ASN1CALL
decode_hdb_entry(const unsigned char *p,
size_t len,
HDB_entry *data,
size_t *size)
{
return decode_HDB_entry(p, len, data, size);
}
int ASN1CALL
decode_hdb_entry_alias(const unsigned char *p,
size_t len,
HDB_entry_alias *data,
size_t *size)
{
return decode_HDB_entry_alias(p, len, data, size);
}
int ASN1CALL
encode_hdb_keyset(unsigned char *p,
size_t len,
const HDB_keyset *data,
size_t *size)
{
return encode_HDB_keyset(p, len, data, size);
}
int ASN1CALL
encode_hdb_entry(unsigned char *p,
size_t len,
const HDB_entry *data,
size_t *size)
{
return encode_HDB_entry(p, len, data, size);
}
int ASN1CALL
encode_hdb_entry_alias(unsigned char *p,
size_t len,
const HDB_entry_alias *data,
size_t *size)
{
return encode_HDB_entry_alias(p, len, data, size);
}
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