This has most of the features needed to act as a kinit that uses GSS
APIs, specifically gss_acquire_cred_from() and gss_store_cred_into2().
It's missing some functionality, such as being able to drive prompts
from AS responses (if we add minor status codes for representing KDC
pre-auth proposals, then we do drive prompts, but we would have to
encode a lot of mechanism-specific knowledge into gsstool).
The point of this commit is to explore:
- GSS functionality for kinit-like actions
- credential store key/value pairs supported by the mechanisms
- document the credential store key/value pairs (in gsstool.1)
that might lead to further enhancements. But gsstool acquire-cred
is quite functional at this point!
We must switch to OpenSSL 3.x, and getting lib/hcrypto to provide
OpenSSL 3.x APIs is too large an undertaking. Plus the hcrypto backend
is not safe, not secure (probably has timing leaks galore), and no one
has the resources to make it a world-class crypto library, so it just
has to go.
There were cases where we weren't negotiating SANON where we should
have. But we really don't want to overdo it. In particular we really
never ever want a user with expired or absent Kerberos credentials (say)
to accidentally negotiate SANON as that will then lead to authorization
errors down the line, and those would be hard to diagnose as they would
be masking the real issue (expired or absent credentials).
So basically either the user passes GSS_C_ANON_FLAG or (and/or) they
call gss_set_neg_mechs() to explicitly request SANON.
Partly authored by me, partly authored by Claude with heavy human
guidance, and reviewed by me.
Windows clients forget GSS_C_MUTUAL_FLAG in some situations where they
use GSS_C_DCE_STYLE, in the assumption that GSS_C_MUTUAL_FLAG is
implied.
Both Windows and MIT as server already imply GSS_C_MUTUAL_FLAG
when GSS_C_DCE_STYLE is used.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15740
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Sequence errors are supplemental information in GSSAPI. This means
that they are not fatal, unless they are returned alongside a failure
error code. This change makes our behaviour the same as MIT's - sequence
errors are non-fatal, and return valid output information.
If the Kerberos v5 principal name is
WELLKNOWN/ANONYMOUS@WELLKNOWN:ANONYMOUS
and the principal type is KRB5_NT_WELLKNOWN, then gss_display_name()
is expected to return GSS_C_NT_ANONYMOUS instead of
GSS_KRB5_NT_PRINCIPAL_NAME. This change matches the behavior of
MIT Kerberos.
We build variants of kinit and test_acquire_cred that define their
own symbols rk_dns_lookup, gethostbyname, gethostbyname2, and
getaddrinfo to print a message and abort. For getaddrinfo, we abort
only if the caller failed to specify AI_NUMERICHOST; otherwise we use
dlsym(RTLD_NEXT, "getaddrinfo") instead.
The new test tests/gss/check-nodns is like tests/gss/check-basic, but
uses kinit_auditdns and test_acquire_cred_auditdns to verify that no
DNS resolution happens.
This test should work and be effective on ELF platforms where the
getaddrinfo function is implemented by the symbol `getaddrinfo'. On
non-ELF platforms it may not be effective -- and on platforms where
the getaddrinfo function is implemented by another symbol (like
`__getaddrinfo50') it may not work, but we can cross that bridge when
we come to it.
Verified manually that the test fails, with the expected error
message and abort, without `block_dns = yes' in krb5-nodns.conf. No
automatic test of the mechanism for now because it might not work on
some platforms.
XXX check-nodns.in is copypasta of check-basic.in, should factor out
the common parts so they don't get out of sync.
Excluded: libtomath and libedit files, most of which appear to be
testing or example code not involved in production, and which are
derived from an upstream that should perhaps have patches submitted
upstream instead.
fix https://github.com/heimdal/heimdal/issues/1111
The interface between the krb5 mechanism and the mechglue API
gsskrb5_extract_authtime_from_sec_context() assumed the authtime would fit into
an uint32_t, which is not the case on platforms where time_t is 64-bit.
Fixes: #1073
SANON cred export/import never worked correctly as the export function was
producing the wrong form of token, which was leading gss_import_cred() to
allocate more than 64MB of memory to parse the SANON exported credential. The
recent change to reduce the default `max_alloc` of krb5_storage exposed this.
We later subtract 8 when calculating the length of the output message
buffer. If padlength is excessively high, this calculation can underflow
and result in a very large positive value.
Now we properly constrain the value of padlength so underflow shouldn't
be possible.
Samba BUG: https://bugzilla.samba.org/show_bug.cgi?id=15134
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
If len_len is equal to total_len - 1 (i.e. the input consists only of a
0x60 byte and a length), the expression 'total_len - 1 - len_len - 1',
used as the 'len' parameter to der_get_length(), will overflow to
SIZE_MAX. Then der_get_length() will proceed to read, unconstrained,
whatever data follows in memory. Add a check to ensure that doesn't
happen.
Samba BUG: https://bugzilla.samba.org/show_bug.cgi?id=15134
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
By decrementing 'pad' only when we know it's safe, we ensure we can't
stray backwards past the start of a buffer, which would be undefined
behaviour.
In the previous version of the loop, 'i' is the number of bytes left to
check, and 'pad' is the current byte we're checking. 'pad' was
decremented at the end of each loop iteration. If 'i' was 1 (so we
checked the final byte), 'pad' could potentially be pointing to the
first byte of the input buffer, and the decrement would put it one
byte behind the buffer.
That would be undefined behaviour.
The patch changes it so that 'pad' is the byte we previously checked,
which allows us to ensure that we only decrement it when we know we
have a byte to check.
Samba BUG: https://bugzilla.samba.org/show_bug.cgi?id=15134
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
