Heimdal's ASN.1 compiler generates code that allows specially
crafted DER encodings of CHOICEs to invoke the wrong free function
on the decoded structure upon decode error. This is known to impact
the Heimdal KDC, leading to an invalid free() of an address partly
or wholly under the control of the attacker, in turn leading to a
potential remote code execution (RCE) vulnerability.
This error affects the DER codec for all CHOICE types used in
Heimdal, though not all cases will be exploitable. We have not
completed a thorough analysis of all the Heimdal components
affected, thus the Kerberos client, the X.509 library, and other
parts, may be affected as well.
This bug has been in Heimdal since 2005. It was first reported by
Douglas Bagnall, though it had been found independently by the
Heimdal maintainers via fuzzing a few weeks earlier.
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>
Any command that uses lib/sl for sub-commands fails to exit with a
non-zero exit code on usage error.
The fix is a one-character change in lib/sl/slc-gram.y.
Affected are all subcommands of:
- ktutil
- kadmin
- heimtools
- hxtool
- gsstool
- kdigest
- iprop-log
- Add an import command that imports JSON as output by
`ktutil list --json --keys`.
This is enables one to filter/edit keytabs with jq!
- Add a `merge` alias for the `copy` command, since that's effectively
what it does.
- Add a `--copy-duplicates` option to the `copy`/`merge` command.
- Add a `--no-create` option to the `get` command.
- Add a `--no-change-keys` option to the `get` command.
- Make `add` complain if it can't finish writing to the keytab.
With this change it's possible to bootstrap a KDC using a client
certificate with a PKINIT SAN for iprop/fqdn. Given such a certificate
one could run ipropd-slave via kinit to pull down the initial copy of
the HDB, then start the KDC services using the HDBGET: keytab.
That should make bootstrapping new secondary KDCs very easy.
One could bootstrap the KDC with such a certificate using, e.g.,
Safeboot (https://github.com/osresearch/safeboot), enrolling the host as
a KDC.
In order to support batch jobs systems that run many users' jobs and
which jobs need credentials, we add a /get-tgts end-point that is a
batched version of the /get-tgt end-point. This end-point returns JSON.
Also, we make GETs optional, default to not-allowed in preference of
POSTs.
We also correct handling of POST (before POSTs with non-zero-length bodies
would cause the server to close the connection), and add additional CSRF
protection features, including the ability to disable all GET requests
for /get-keys and /get-config.
We set the timestamp field of krb5_keytab_entry in every case in-tree,
so we should not clobber it in krb5_kt_add_entry(). This is very
important in the context of virtual service principals, as the timestamp
of the keys in the keytab is a clue to when they must be refetched!
The idea with HEIM_JSON_F_TRY_DECODE_DATA is that on parsing of JSON
texts, if we find a base64-encoded string, decode it. But a lot of
strings that aren't base64-encoded can be decoded anyways, leaving a
mess.
Insted we should -in a future commit- implement this only for the string
values of "heimdal-type-data-76d7fca2-d0da-4b20-a126-1a10f8a0eae6" names
in singleton objects.
- Add HEIM_JSON_F_ESCAPE_NON_ASCII to indicate that non-ASCII must be
escaped as \uXXXX.
- Add HEIM_JSON_F_NO_ESCAPE_NON_ASCII to force non-escaping of BMP
codepoints.
- If the locale's codeset is not UTF-8 and
HEIM_JSON_F_NO_ESCAPE_NON_ASCII is not set, then set
HEIM_JSON_F_ESCAPE_NON_ASCII.
- Add flags for indenting with 2, 4, or 8 spaces, still defaulting to
tabs if none of those are set.
- Don't emit a newline before emitting scalar values in dicts.
- Fix markup
- Specific quoted command line for Visual Studio
build
- Caveat about line ending for gawk
- Add comments about python versions
- makeinfo.exe is no longer available from cygwin
- Add some words about APPVER setting
Without the change the build fails as:
CC hdb-ldap.lo
hdb-ldap.c:2109:5: warning: initialization of 'unsigned char:1' from 'krb5_error_code (*)(struct krb5_context_data *, void **)' {aka 'int (*)(struct krb5_context_data *, void **)'} makes integer from pointer without a cast [-Wint-conversion]
2109 | init,
| ^~~~
hdb-ldap.c:2109:5: note: (near initialization for 'hdb_ldapi_interface.is_file_based')
hdb-ldap.c:2109:5: error: initializer element is not computable at load time
hdb-ldap.c:2109:5: note: (near initialization for 'hdb_ldapi_interface.is_file_based')
hdb-ldap.c:2110:5: warning: initialization of 'unsigned char:1' from 'void (*)(void *)' makes integer from pointer without a cast [-Wint-conversion]
2110 | fini,
| ^~~~
hdb-ldap.c:2110:5: note: (near initialization for 'hdb_ldapi_interface.can_taste')
hdb-ldap.c:2110:5: error: initializer element is not computable at load time
hdb-ldap.c:2110:5: note: (near initialization for 'hdb_ldapi_interface.can_taste')
hdb-ldap.c:2111:5: warning: initialization of 'krb5_error_code (*)(struct krb5_context_data *, void **)' {aka 'int (*)(struct krb5_context_data *, void **)'} from incompatible pointer type 'char *' [-Wincompatible-pointer-types]
2111 | "ldapi",
| ^~~~~~~
hdb-ldap.c:2111:5: note: (near initialization for 'hdb_ldapi_interface.init')
hdb-ldap.c:2112:5: warning: initialization of 'void (*)(void *)' from incompatible pointer type 'krb5_error_code (*)(struct krb5_context_data *, HDB **, const char *)' {aka 'int (*)(struct krb5_context_data *, HDB **, const char *)'} [-Wincompatible-pointer-types]
2112 | hdb_ldapi_create
| ^~~~~~~~~~~~~~~~
hdb-ldap.c:2112:5: note: (near initialization for 'hdb_ldapi_interface.fini')
hdb-ldap.c:2113:1: warning: missing initializer for field 'prefix' of 'struct hdb_method' [-Wmissing-field-initializers]
2113 | };
| ^
Started failing when commit 93ada1fbf ("hdb: Remove default HDB backend
footgun") added extra fields to 'struct hdb_method'.
The 'bits' parameter to select_dh_group() is the minimum acceptable
bit size. Rename 'bits' to 'min_bits' and fix the comparision
with krb5_dh_moduli.bits to ensure that DH groups whose bit size
is the minimum acceptable are not excluded.
Fixes#1002
Reported-By: Julien Rische (GitHub: jrisc)
Heimdal supports the 2 mandatory MODP groups (group 2 and group 14)
according to RFC4556, however group 14 is defined with a size of
1760 bits instead of 2048.
Fixes#1001
Reported-by: Julien Rische (GitHub: jrisc)
Noticed missing target directory dependency as a build failure in
`make --shuffle` mode (added in https://savannah.gnu.org/bugs/index.php?62100):
CC test_common.o
In file included from test_common.c:34:
krb5/gsskrb5_locl.h:42:10: fatal error: gkrb5_err.h: No such file or directory
42 | #include <gkrb5_err.h>
| ^~~~~~~~~~~~~
compilation terminated.
make[3]: *** [Makefile:2347: test_common.o] Error 1 shuffle=1656680590
The change moves gkrb5_err.h and friends to BUILT_SOURCES
to guarantee their presence when main build starts.
