This commit adds support for proof of posession to the kx509 protocol by
using PKCS#10 CSRs.
This allows conveyance of extReq CSR attributes requesting desired
Certificate Extensions.
This commit adds support for kx509 in libkrb5, and revamps the KDC's
kx509 service (fixing bugs, adding features).
Of note is that kx509 is attempted optimistically by the client, with
the certificate and private key stored in the ccache, and optionally in
an external PEM or DER file.
NOTE: We do not optimistically use kx509 in krb5_cc_store_cred() if the
ccache is a MEMORY ccache so we don't generate a key when
accepting a GSS context with a delegated credential.
kx509 protocol issues to be fixed in an upcoming commit:
- no proof of possession (this is mostly not too bad, but we'll want to
fix it by using CSRs)
- no algorithm agility (only plain RSA is supported)
- very limited (no way to request any options in regards to the
requested cert)
- error codes are not very useful
Things we're adding in this commit:
- libkrb5 kx509 client
- automatic kx509 usage hooked in via krb5_cc_store_cred() of start TGT
- per-realm templates on the KDC side
- per-realm issuer certificates
- send error messages on the KDC side
(this is essential to avoid client-side timeouts on error)
- authenticate as many error messages
- add a protocol probe feature so we can avoid generating a
keypair if the service is not enabled
(once we add support for ECC algorithms we won't need this
anymore; the issue is that RSA keygen is slow)
- support for different types of client principals, not just username:
- host-based service and domain-based service, each with its own
template set per-{realm, service} or per-service
(the idea is to support issuance of server certificates too, not
just client/user certs)
- more complete support for SAN types
- tests (including that PKINIT->kx509->PKINIT works, which makes it
possible to have "delegation" of PKIX credentials by just delegating
Kerberos credentials)
- document the protocol in lib/krb5/kx509.c
Future work:
- add option for longer-ticket-lifetime service certs
- add support for ECDSA, and some day for ed25519 and ed448
- reuse private key when running kinit
(this will require rethinking how we trigger optimistic kx509
usage)
- HDB lookup for:
- optional revocation check (not strictly necessary)
- adding to certificates those SANs listed in HDB
- hostname aliases (dNSName SANs)
- rfc822Name (email)
- XMPP SANs
- id-pkinit-san (a user could have aliases too)
- support username wild-card A RRs, ala OSKT/krb5_admin
i.e., if a host/f.q.d.n principal asks for a certificate for
some service at some-label.f.q.d.n, then issue it
(this is not needed at OSKT sites because OSKT already
supports keying such service principals, which means kx509
will issue certificates for them, however, it would be nice
to be able to have this independent of OSKT)
(a better way to do this would be to integrate more of OSKT
into Heimdal proper)
- a kx509 command, or heimtools kx509 subcommand for explicitly
attempting use of the kx509 protocol (as opposed to implicit, as is
done in kinit via krb5_cc_store_cred() magic right now)
Issues:
- optimistically trying kx509 on start realm TGT store -> timeout issues!
- newer KDCs will return errors because of this commit; older ones
will not, which causes timouts
- need a separate timeout setting for kx509 for optimistic case
- need a [realm] config item and DNS SRV RR lookup for whether a
realm is expected to support kx509 service
Anonymous PKINIT tickets discard the realm information used to locate the
issuing AS. Store the issuing realm in the credentials cache in order to locate
a KDC which can renew them.
even if tgt used an enctype with a different checksum.
Per [MS-SFU] 2.2.1 PA-FOR-USER the checksum is always
HMAC_MD5, and that's what Windows and MIT clients send.
In heimdal both the client and kdc use instead the
checksum of the tgt, and therefore work with each other
but windows and MIT clients fail against heimdal KDC.
Both Windows and MIT KDC would allow any keyed checksum
to be used so Heimdal client work fine against it.
Change Heimdal KDC to allow HMAC_MD5 even for non RC4
based tgt in order to support per-spec clients.
Signed-off-by: Isaac Boukris <iboukris@gmail.com>
- Add --keepold/keepallold/pruneall options to various kadmin/ktutil
commands. Default behavior to "prune old keys".
- When setting keys for a service, we need to specify enctypes for it:
- Always use kadm5_randkey_principal_3() instead of the older
kadm5_randkey_principal().
- Add krb5_string_to_keysalts2(), like MIT's krb5_string_to_keysalts(),
but with a context, and simpler.
- Add --enctypes options to various kadmin/ktutil commands.
- Add [libdefaults] supported_enctypes param with enctype[:salttype]
list.
- Add [realms] realm supported_enctypes param with enctype[:salttype]
list.
Default to aes128-cts-hmac-sha1-96:normal.
The meaning of the two is different and we should
not implicitly set both if one was requested (this
aligns the logic with MIT kinit -C/-E options).
Signed-off-by: Isaac Boukris <iboukris@gmail.com>
This patch adds the "enforce_on_admin_set" configuration knob in the
[password_quality] section. When this is enabled, administrative password
changes via the kadmin or kpasswd protocols will be subject to password quality
checks. (An administrative password change is one where the authenticating
principal is different to the principal whose password is being changed.)
Note that kadmin running in local mode (-l) is unaffected by this patch.
From a suggestion by nicowilliams, put double quotes aroung the varaible
$foopassword in case the password contains whitespace or other special
characters.
When we use a custom patch that makes strong passwords required even for
administrators the check-kadmin test will fail because "foo" (the password
used in check-kadmin.in) is not a strong password. So, we make the
password used in check-kadmin.in settable as a parameter. This way, we
only have to change one line of check-kadmin.in rather than a dozen to get
check-kadmin to pass when using the strong-passwords everywhere patch.
Note that this change makes no real change to any of the tests in
check-kadmin.in: no tests are changed, removed, or added.
Though a race was never observed, the re-sync, slave DB deletion,
master changes and restart did not take into account late changes
in the master before slave down.
Creation of a random key HDB entry takes 3 updates, not one. Instead of
hard-coding this magic count, wait for the appearance of the expected
entry with no "invalid" flag among its attributes.
Commit f469fc6 (2010-10-02) inadvertently caused the previous hop realm
to not be added to the transit path of issued tickets. This may, in
some cases, enable bypass of capath policy in Heimdal versions 1.5
through 7.2.
Note, this may break sites that rely on the bug. With the bug some
incomplete [capaths] worked, that should not have. These may now break
authentication in some cross-realm configurations.
The output of `wc -l` includes leading white-space, and at least
in FreeBSD 11, `expr 1 + "$foo"` fails when "$foo" (captured as
`wc -l` output) has leading whitespace. Instead, just emit one
more line for "wc" to count.
Also implement KDC hierarchical transit policy checks. The "hier_capaths"
parameter defaults to "yes" in [libdefaults] or can be set explicitly in
[realms] per-realm.
CVE-2016-2400
kadmind(8) was not checking for 'add' permission to aliases added via
kadm5_modify_principal(). This is a security vulnerability. The impact
of this vulnerability is mostly minor because most sites that use
kadmind(8) generally grant roughly the same level of permissions to all
administrators. However, the impact will be higher for sites that grant
modify privileges to large numbers of less-privileged users.
From what we know of existing deployments of Heimdal, it seems very
likely that the impact of this vulnerability will be minor for most
sites.
We used to update the iprop log and HDB in different orders depending on
the kadm5 operation, which then led to various race conditions.
The iprop log now functions as a two-phase commit (with roll forward)
log for HDB changes. The log is auto-truncated, keeping the latest
entries that fit in a configurable maximum number of bytes (defaults to
50MB). See the log-max-size parameter description in krb5.conf(5).
The iprop log format and the protocol remain backwards-compatible with
earlier versions of Heimdal. This is NOT a flag-day; there is NO need
to update all the slaves at once with the master, though it is advisable
in general. Rolling upgrades and downgrades should work.
The sequence of updates is now (with HDB and log open and locked):
a) check that the HDB operation will succeed if attempted,
b) append to iprop log and fsync() it,
c) write to HDB (which should fsync()),
d) mark last log record committed (no fsync in this case).
Every kadm5 write operation recover transactions not yet confirmed as
committed, thus there can be at most one unconfirmed commit on a master
KDC.
Reads via kadm5_get_principal() also attempt to lock the log, and if
successful, recover unconfirmed transactions; readers must have write
access and must win any race to lock the iprop log.
The ipropd-master daemon also attempts to recover unconfirmed
transactions when idle.
The log now starts with a nop record whose payload records the offset of
the logical end of the log: the end of the last confirmed committed
transaction. This is kown as the "uber record". Its purpose is
two-fold: act as the confirmation of committed transactions, and provide
an O(1) method of finding the end of the log (i.e., without having to
traverse the entire log front to back).
Two-phase commit makes all kadm5 writes single-operation atomic
transactions (though some kadm5 operations, such as renames of
principals, and changes to principals' aliases, use multiple low-level
HDB write operations, but still all in one transaction). One can still
hold a lock on the HDB across many operations (e.g., by using the lock
command in a kadmin -l or calling kadm5_lock()) in order to push
multiple transactions in sequence, but this sequence will not be atomic
if the process or host crashes in the middle.
As before, HDB writes which do not go through the kadm5 API are excluded
from all of this, but there should be no such writes.
Lastly, the iprop-log(1) command is enhanced as follows:
- The dump, last-version, truncate, and replay sub-commands now have an
option to not lock the log. This is useful for inspecting a running
system's log file, especially on slave KDCs.
- The dump, last-version, truncate, and replay sub-commands now take an
optional iprop log file positional argument, so that they may be used
to inspect log files other than the running system's
configured/default log file.
Extensive code review and some re-writing for clarity by Viktor Dukhovni.
The following sequence of events results in slave B having a stale HDB:
- slave A connects to master, master dumps HDB for the slave
- kadm5 operations
- slave B connects to master, master sends previously dumped HDB
slave B won't discover any updates until the next transaction.
The fix is simple: the slave should immediately call ihave() after
receiving a complete HDB.
