Heimdal's HDB plugin interface, and hence Samba's KDC that depends upon
it, doesn't work on 32-bit builds due to structure fields being arranged
in the wrong order. This problem presents itself in the form of
segmentation faults on 32-bit systems, but goes unnoticed on 64-bit
builds thanks to extra structure padding absorbing the errant fields.
This commit reorders the HDB plugin structure fields to prevent crashes
and introduces a common macro to ensure every plugin presents a
consistent interface.
Samba BUG: https://bugzilla.samba.org/show_bug.cgi?id=15110
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
In order to resolve some shift/reduce conflicts in the ASn.1 compiler's
grammar we need to be strict about value names starting with lower case
and type names starting with upper-case.
Remove hdb_entry_ex and revert to the original design of hdb_entry (except with
an additional context member in hdb_entry which is managed by the free_entry
method in HDB).
Decorate HDB_entry with context and move free_entry callback into HDB structure
itself. Requires updating hdb_free_entry() signature to include HDB parameter.
A follow-up commit will consolidate hdb_entry_ex (which has a single hdb_entry
member) into hdb_entry.
Instead of having distinct preauth success/failure events for different
mechanisms, have a single event; the mechanism can be disambiguated by querying
the HDB_REQUEST_KV_PA_NAME key.
Note: there is still an explicit event for long-term key-based success/failure
in order to help the backend implement lockout.
Audit failure (HDB_AUTH_EVENT_PREAUTH_FAILED) in the main preauth loop, rather
than in each mechanism. Success is still audited in the mechanism to allow
client pre-authentication success to be noted even if something subsequent
(e.g. encoding a reply, memory allocation) fails. The generic catch-all for
success remains.
The auth event details audit key (formerly, parameter to auth_status)
contained, variously, an encryption type name; a PKINIT client certificate
name; or, a GSS initiator name. Audit these instead using individual keys that
reflect the values' contents.
Make Samba-specific HDB auth status API a wrapper on the existing auditing API,
with a view towards unifying the two APIs in a future commit.
The term "auth status" is replaced with "auth event", and the HDB auth_status
method is replaced with a more general purpose audit method which has access to
the entire request structure.
We now pass on the original client name and the client address to allow
consistent audit logging in Samba across multiple protocols.
We also log the authentication duration.
This is not a general purpose profiling solution, but in Smaba
these JSON logs are already being generated and stored, so this
is worth adding.
Some administrators are very keen to know how long authentication
takes, particularly due to long replication transactions in other
Samba processes.
We use config->db[0] to find the first database to record incorrect
users.
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
(Similar to Samba commit f498ba77df2313e78863e5f2706840c43e232a96 and
bb2a1c6b3eaccf114ac3f3b5b51f57828a04996)
[metze@samba.org: improved for heimdal upstream]
Signed-off-by: Stefan Metzmacher <metze@samba.org>
[abartlet@samba.org: improved again for Heimdal based on feedback]
Assists Samba to address CVE-2020-25719
Again, this may be contary to RFC4120 3.3.3
https://datatracker.ietf.org/doc/html/rfc4120/#section-3.3.3
(clearer at the GSS spec here:
https://datatracker.ietf.org/doc/html/draft-swift-win2k-krb-user2user-03 )
as server-name is decribed as optional, however Windows AD and Samba
both require that the server-name exist and be a valid SPN matching
the provided TGT.
The lookup of SPN -> entry ensures that the SPN the client thought it
was connecting to was held by the target server. it could be the
typical user principal, or a service principal, but needs to be checked
for the client not to be fooled into connecting to the wrong service.
The check is the same as needed for S4U2Self so the same HDB hook is re-used.
Samba BUG: https://bugzilla.samba.org/show_bug.cgi?id=14873
(Similar to Samba commit f08e6ac86226dcd939fd0e40b6f7dc80c5c00e79)
Assists Samba to address CVE-2020-25719
Passing in target_server as a string principal means that for
an alias we must looking up the DB twice.
This is subject to a race and is a poor use of resources,
so instead just pass in the record we
already got when trying to confirm that the server in
S4U2Self is the same as the requesting client.
We also avoid doing a name comparison if the HDB plugin provides
a validation hook, this allows the HDB layer more freedom
to choose how to handle things.
In Samba AD the client record has already been bound to the the
original client by the SID check in the PAC, so the record is
known to match the ticket.
Likewise by looking up server only once we ensure that the
keys looked up originally (to decrypt) are in the record
we confirm the SID for here.
Samba BUG: https://bugzilla.samba.org/show_bug.cgi?id=14686
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
(Based on Samba commit 05898cfb139ae0674c8251acc9d64c4c3d4c8376)
For Samba the fast key is not stored in the replicated DB, so
this helps Samba find it in the Samba hdb module.
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Status:
- And it works!
- We have an extensive test based on decoding a rich EK certficate.
This test exercises all of:
- decoding
- encoding with and without decoded open types
- copying of decoded values with decoded open types
- freeing of decoded values with decoded open types
Valgrind finds no memory errors.
- Added a manual page for the compiler.
- rfc2459.asn1 now has all three primary PKIX types that we care about
defined as in RFC5912, with IOS constraints and parameterization:
- `Extension` (embeds open type in an `OCTET STRING`)
- `OtherName` (embeds open type in an `ANY`-like type)
- `SingleAttribute` (embeds open type in an `ANY`-like type)
- `AttributeSet` (embeds open type in a `SET OF ANY`-like type)
All of these use OIDs as the open type type ID field, but integer
open type type ID fields are also supported (and needed, for
Kerberos).
That will cover every typed hole pattern in all our ASN.1 modules.
With this we'll be able to automatically and recursively decode
through all subject DN attributes even when the subject DN is a
directoryName SAN, and subjectDirectoryAttributes, and all
extensions, and all SANs, and all authorization-data elements, and
PA-data, and...
We're not really using `SingleAttribute` and `AttributeSet` yet
because various changes are needed in `lib/hx509` for that.
- `asn1_compile` builds and recognizes the subset of X.681/682/683 that
we need for, and now use in, rfc2459.asn1. It builds the necessary
AST, generates the correct C types, and generates templating for
object sets and open types!
- See READMEs for details.
- Codegen backend not tested; I won't make it implement automatic open
type handling, but it should at least not crash by substituting
`heim_any` for open types not embedded in `OCTET STRING`.
- We're _really_ starting to have problems with the ITU-T ASN.1
grammar and our version of it...
Type names have to start with upper-case, value names with
lower-case, but it's not enough to disambiguate.
The fact the we've allowed value and type names to violate their
respective start-with case rules is causing us trouble now that we're
adding grammar from X.681/682/683, and we're going to have to undo
that.
In preparation for that I'm capitalizing the `heim_any` and
`heim_any_set` types, and doing some additional cleanup, which
requires changes to other parts of Heimdal (all in this same commit
for now).
Problems we have because of this:
- We cannot IMPORT values into modules because we have no idea if a
symbol being imported refers to a value or a type because the only
clue we would have is the symbol's name, so we assume IMPORTed
symbols are for types.
This means we can't import OIDs, for example, which is super
annoying.
One thing we might be able to do here is mark imported symbols as
being of an undetermined-but-not-undefined type, then coerce the
symbol's type the first time it's used in a context where its type
is inferred as type, value, object, object set, or class. (Though
since we don't generate C symbols for objects or classes, we won't
be able to import them, especially since we need to know them at
compile time and cannot defer their handling to link- or
run-time.)
- The `NULL` type name, and the `NULL` value name now cause two
reduce/reduce conflicts via the `FieldSetting` production.
- Various shift/reduce conflicts involving `NULL` values in
non-top-level contexts (in constraints, for example).
- Currently I have a bug where to disambiguate the grammar I have a
CLASS_IDENTIFIER token that is all caps, while TYPE_IDENTIFIER must
start with a capital but not be all caps, but this breaks Kerberos
since all its types are all capitalized -- oof!
To fix this I made it so class names have to be all caps and
start with an underscore (ick).
TBD:
- Check all the XXX comments and address them
- Apply this treatment to Kerberos! Automatic handling of authz-data
sounds useful :)
- Apply this treatment to PKCS#10 (CSRs) and other ASN.1 modules too.
- Replace various bits of code in `lib/hx509/` with uses of this
feature.
- Add JER.
- Enhance `hxtool` and `asn1_print`.
Getting there!
Do not allow a change in build configuration time default HDB backend
selection cause existing default HDBs to not be possible to open.
Otherwise such a change will cause a KDC configured to use the default
HDB (i.e., without setting it in the "database" stanza in the "[kdc]"
section of krb5.conf) to not start.
The new [hdb] new_service_key_delay parameter should not apply to
principal entries when used as clients. Otherwise new passwords would
not take effect immediately, and that would be very confusing.
This is a large commit that adds several features:
- Revamps and moves virtual host-based service principal functionality
from kdc/ to lib/hdb/ so that it may be automatically visible to
lib/kadm5/, as well as kadmin(1)/kadmind(8) and ktutil(1).
The changes are backwards-incompatible.
- Completes support for documenting a service principal's supported
enctypes in its HDB entry independently of its long-term keys. This
will reduce HDB bloat by not requiring that service principals have
more long-term keys than they need just to document the service's
supported enctypes.
- Adds support for storing krb5.conf content in principals' HDB
entries. This may eventually be used for causing Heimdal KDC
services to reconfigure primary/secondary roles automatically by
discovering the configured primary in an HDB entry for the realm.
For now this will be used to help reduce the amount of configuration
needed by clients of an upcoming HTTP binding of the kadmin service.
The hdb_method functions cannot be KRB5_LIB_CALL as lib/hdb is not
lib/krb5. KRB5_LIB_CALL will be inconsistently defined.
This inconsistency resulted in crashes of test_hdbplugin on 32-bit
Windows.
Change-Id: I4cf8d3ef76f31a3cae923df234a19610d956e7ee
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.
Before this change Heimdal could read KDBs. Now it can write to
them too.
Heimdal can now also dump HDBs (including KDBs) in MIT format, which
can then be imported with kdb5_util load.
This is intended to help in migrations from MIT to Heimdal by
allowing migrations from Heimdal to MIT so that it is possible
to rollback from Heimdal to MIT should there be any issues. The
idea is to allow a) running Heimdal kdc/kadmind with a KDB, or
b) running Heimdal with an HDB converted from a KDB and then
rollback by dumping the HDB and loading a KDB.
Note that not all TL data types are supported, only two: last
password change and modify-by. This is the minimum necessary.
PKINIT users may need to add support for KRB5_TL_USER_CERTIFICATE,
and for databases with K/M history we may need to add KRB5_TL_MKVNO
support.
Support for additional TL data types can be added in
lib/hdb/hdb-mitdb.c:_hdb_mdb_value2entry() and
lib/hdb/print.c:entry2mit_string_int().
This will be used to indicate to the backend if a fetch is for
an AS REQ or TGS REQ. Samba needs to take some action in the
HDB_F_FOR_TGS_REQ case and always canonicalize the principal
names, even without HDB_F_CANON.
metze
Signed-off-by: Love Hörnquist Åstrand <lha@h5l.org>
This makes it a bit easier to find libhdb in e.g. configure tests and
is consistent with the main header files for the other Heimdal
libraries, none of which has any prerequisite other headers.
Signed-off-by: Love Hornquist Astrand <lha@h5l.org>
This should allow master key rollover.
(but the real reason is to allow multiple krbtgt accounts, as used by
Active Directory to implement RODC support)
Signed-off-by: Love Hornquist Astrand <lha@h5l.org>
This allows us to resolve multiple forms of a name, allowing for
example machine$@REALM to get an S4U2Self ticket for
host/machine@REALM.
Andrew Bartlett
Signed-off-by: Love Hornquist Astrand <lha@h5l.org>
