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This means ldb_tevent_debug() is only called for TEVENT_DEBUG_TRACE.
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
Fix the following error observed running samba.test.registry
compiled with clang-17 and UBsan:
lib/ldb/common/ldb_ldif.c:881:9: runtime error: applying non-zero offset 137438953440 to null pointer
#0 0x7faa0eb3932f in ldb_ldif_read lib/ldb/common/ldb_ldif.c:881
#1 0x7faa0eb3aec6 in ldb_ldif_read_string lib/ldb/common/ldb_ldif.c:1004
#2 0x7faa077ed759 in dsdb_set_schema_from_ldif source4/dsdb/schema/schema_set.c:1113
#3 0x7faa068fcbbf in py_dsdb_set_schema_from_ldif source4/dsdb/pydsdb.c:929
#4 0x7faa1d1d4507 in cfunction_call (/lib64/libpython3.11.so.1.0+0x1d4507)
[... a lot of Python calls skipped...]
I.e. number of elements should be checked against zero
before making an attempt to access an element by index.
Signed-off-by: Dmitry Antipov <dantipov@cloudlinux.com>
Reviewed-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Computing a pointer that points outside of an array, and not to one past
the last element, is undefined behaviour. To avoid this, do our
comparisons in terms of lengths, not pointers.
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andreas Schneider <asn@samba.org>
If the LDB_UNPACK_DATA_FLAG_NO_ATTRS flag is set, we don't return any
elements, so we should set num_elements accordingly. This ensures
callers don't try to access elements that aren't there.
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andreas Schneider <asn@samba.org>
Commit bed9efa6cd introduced
ldb_msg_add_linearized_dn() to replace ldb_msg_add_dn(), but retained
the now-incorrect associated comment. The comment later made its way
into a function added later by commit 'CVE-2022-32746 ldb: Add functions
for appending to an ldb_message'.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15008
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andreas Schneider <asn@samba.org>
Redaction may be expensive if we end up needing to fetch a security
descriptor to verify rights to an attribute. Checking the search scope
is probably cheaper, so do that first.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15270
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
This makes it less likely that we forget to handle a case.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15270
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Add a hook, acl_redact_msg_for_filter(), in the aclread module, that
marks inaccessible any message elements used by an LDAP search filter
that the user has no right to access. Make the various ldb_match_*()
functions check whether message elements are accessible, and refuse to
match any that are not. Remaining message elements, not mentioned in the
search filter, are checked in aclread_callback(), and any inaccessible
elements are removed at this point.
Certain attributes, namely objectClass, distinguishedName, name, and
objectGUID, are always present, and hence the presence of said
attributes is always allowed to be checked in a search filter. This
corresponds with the behaviour of Windows.
Further, we unconditionally allow the attributes isDeleted and
isRecycled in a check for presence or equality. Windows is not known to
make this special exception, but it seems mostly harmless, and should
mitigate the performance impact on searches made by the show_deleted
module.
As a result of all these changes, our behaviour regarding confidential
attributes happens to match Windows more closely. For the test in
confidential_attr.py, we can now model our attribute handling with
DC_MODE_RETURN_ALL, which corresponds to the behaviour exhibited by
Windows.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15270
Pair-Programmed-With: Andrew Bartlett <abartlet@samba.org>
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
ldb_filter_attrs() previously did too much. Now its replacement,
ldb_filter_attrs_in_place(), only does the actual filtering, while
taking ownership of each element's values is handled in a separate
function, ldb_msg_elements_take_ownership().
Also, ldb_filter_attrs_in_place() no longer adds the distinguishedName
to the message if it is missing. That is handled in another function,
ldb_msg_add_distinguished_name().
As we're now modifying the original message rather than copying it into
a new one, we no longer need the filtered_msg parameter.
We adapt a test, based on ldb_filter_attrs_test, to exercise the new
function.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15270
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
At present this function is an exact duplicate of ldb_filter_attrs(),
but in the next commit we shall modify it to work in place, without the
need for the allocation of a second message.
The test is a near duplicate of the existing test for
ldb_filter_attrs().
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15270
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Many places in Samba depend upon various components of an ldb message
being talloc allocated, and hence able to be used as talloc contexts.
The elements and values of an unpacked ldb message point to unowned data
inside the memory-mapped database, and this function ensures that such
messages have talloc ownership of said elements and values.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15270
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
These functions allow us to parse any value of a message element, not
only the first. They also unambiguously indicate whether an error has
occurred.
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
This is needed in order to process schema updates.
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
The value can be quite large, the allocation will take much
longer than the actual match and is repeated per candidate
record.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15331
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Joseph Sutton <josephsutton@catalyst.net.nz>
The failure in question would have to be a `talloc_strdup(dn, "")` in
ldb_dn_from_ldb_val().
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Currently, there are many places where we use ldb_msg_add_empty() to add
an empty element to a message, and then call ldb_msg_add_value() or
similar to add values to that element. However, this performs an
unnecessary search of the message's elements to locate the new element.
Moreover, if an element with the same attribute name already exists
earlier in the message, the values will be added to that element,
instead of to the intended newly added element.
A similar pattern exists where we add values to a message, and then call
ldb_msg_find_element() to locate that message element and sets its flags
to (e.g.) LDB_FLAG_MOD_REPLACE. This also performs an unnecessary
search, and may locate the wrong message element for setting the flags.
To avoid these problems, add functions for appending a value to a
message, so that a particular value can be added to the end of a message
in a single operation.
For ADD requests, it is important that no two message elements share the
same attribute name, otherwise things will break. (Normally,
ldb_msg_normalize() is called before processing the request to help
ensure this.) Thus, we must be careful not to append an attribute to an
ADD message, unless we are sure (e.g. through ldb_msg_find_element())
that an existing element for that attribute is not present.
These functions will be used in the next commit.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15009
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Using the newly added ldb flag, we can now detect when a message has
been shallow-copied so that its elements share their values with the
original message elements. Then when adding values to the copied
message, we now make a copy of the shared values array first.
This should prevent a use-after-free that occurred in LDB modules when
new values were added to a shallow copy of a message by calling
talloc_realloc() on the original values array, invalidating the 'values'
pointer in the original message element. The original values pointer can
later be used in the database audit logging module which logs database
requests, and potentially cause a crash.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15009
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
When making a shallow copy of an ldb message, mark the message elements
of the copy as sharing their values with the message elements in the
original message.
This flag value will be heeded in the next commit.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15009
Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
As seen in CVE-2021-20277, ldb_handler_fold() has been making mistakes
when collapsing spaces down to a single space.
This patch fixes the way it handles internal spaces (CVE-2021-20277
was about leading spaces), and involves a rewrite of the parsing loop.
The bug has a detailed description of the problem.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14656
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Wed Apr 7 03:16:39 UTC 2021 on sn-devel-184
We run one character over in comparing all the bytes in two ldb_vals.
In almost all circumstances both ldb_vals would have an allocated '\0'
in the overrun position, but it is best not to rely on that.
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
A DN string with lots of trailing space can cause ldb_dn_explode() to
put a zero byte in the wrong place in the heap.
When a DN string has a value represented with trailing spaces,
like this
"CN=foo ,DC=bar"
the whitespace is supposed to be ignored. We keep track of this in the
`t` pointer, which is NULL when we are not walking through trailing
spaces, and points to the first space when we are. We are walking with
the `p` pointer, writing the value to `d`, and keeping the length in
`l`.
"CN=foo ,DC= " ==> "foo "
^ ^ ^
t p d
--l---
The value is finished when we encounter a comma or the end of the
string. If `t` is not NULL at that point, we assume there are trailing
spaces and wind `d and `l` back by the correct amount. Then we switch
to expecting an attribute name (e.g. "CN"), until we get to an "=",
which puts us back into looking for a value.
Unfortunately, we forget to immediately tell `t` that we'd finished
the last value, we can end up like this:
"CN=foo ,DC= " ==> ""
^ ^ ^
t p d
l=0
where `p` is pointing to a new value that contains only spaces, while
`t` is still referring to the old value. `p` notices the value ends,
and we subtract `p - t` from `d`:
"CN=foo ,DC= " ==> ? ""
^ ^ ^
t p d
l ~= SIZE_MAX - 8
At that point `d` wants to terminate its string with a '\0', but
instead it terminates someone else's byte. This does not crash if the
number of trailing spaces is small, as `d` will point into a previous
value (a copy of "foo" in this example). Corrupting that value will
ultimately not matter, as we will soon try to allocate a buffer `l`
long, which will be greater than the available memory and the whole
operation will fail properly.
However, with more spaces, `d` will point into memory before the
beginning of the allocated buffer, with the exact offset depending on
the length of the earlier attributes and the number of spaces.
What about a longer DN with more attributes? For example,
"CN=foo ,DC= ,DC=example,DC=com" -- since `d` has moved out of
bounds, won't we continue to use it and write more DN values into
mystery memory? Fortunately not, because the aforementioned allocation
of `l` bytes must happen first, and `l` is now huge. The allocation
happens in a talloc_memdup(), which is by default restricted to
allocating 256MB.
So this allows a person who controls a string parsed by ldb_dn_explode
to corrupt heap memory by placing a single zero byte at a chosen
offset before the allocated buffer.
An LDAP bind request can send a string DN as a username. This DN is
necessarily parsed before the password is checked, so an attacker does
not need proper credentials. The attacker can easily cause a denial of
service and we cannot rule out more subtle attacks.
The immediate solution is to reset `t` to NULL when a comma is
encountered, indicating that we are no longer looking at trailing
whitespace.
Found with the help of Honggfuzz.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14595
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
For a string that had N spaces at the beginning, we would
try to move N bytes beyond the end of the string.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14655
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
There is no flags argument.
There are more URI forms.
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Jeremy Allison <jra@samba.org>
c.f. the identical static function in lib/ldb-samba/ldif_handlers.c
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Jeremy Allison <jra@samba.org>
We already ensure the no-trailing-asterisk case ends at the end of the
string.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14044
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Björn Jacke <bjacke@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
