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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>
A wildcard search is divided into chunks by the asterisks. While most
chunks match the first suitable string, the last chunk matches the
last possible string (unless there is a trailing asterisk, in which
case this distinction is moot).
We always knew this in our hearts, but we tried to do it in a funny
complicated way that stepped through the string, comparing here and
there, leading to CVE-2019-3824 and missed matches (bug 14044).
With this patch, we just jump to the end of the string and compare it.
As well as being correct, this should also improve performance, as the
previous algorithm involved a quadratic loop of erroneous memmem()s.
See https://tools.ietf.org/html/rfc4517
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>
Pair-Programmed-With: Björn Baumbach <bb@sernet.de>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Björn Baumbach <bb@sernet.de>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Otherwise a malformed control with unexpected NULL data will segfault
ldb_control_to_string(), though this is not very likely to affect
anyone in practice as converting controls to strings is rarely
necessary. If it happens at all in Samba it is in Python code.
Found by Honggfuzz using fuzz_ldb_parse_control.
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andreas Schneider <asn@samba.org>
Autobuild-User(master): Douglas Bagnall <dbagnall@samba.org>
Autobuild-Date(master): Wed Jul 29 04:43:23 UTC 2020 on sn-devel-184
Prevent use after free issues if ldb_lock_backend_callback is called
twice, usually due to ldb_module_done being called twice. This can happen if a
module ignores the return value from function a function that calls
ldb_module_done as part of it's error handling.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14364
Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Limit the number of nested conditionals allowed by ldb_parse tree to
128, to avoid potential stack overflow issues.
Credit Oss-Fuzz
REF: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=19508
Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Gary Lockyer <gary@samba.org>
Autobuild-Date(master): Sun May 10 23:21:08 UTC 2020 on sn-devel-184
TALLOC_FREE the ldb_control allocated in ldb_parse_control_from_string
when none of the cases match.
Credit to OSS-Fuzz
Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: David Disseldorp <ddiss@samba.org>
Fix ASAN detected use after free. No security implications as the
talloc_free is followed immediately by the print statement and the value
printed is an integer
Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
The print functions used in Samba NULL terminate, but do not assume they will
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14049
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
This is beyond the normal level of clarity we expect in Samba, and is of course
rudundent, but this is a complex routine that has confusing tests, some of
pointers and some of boolean state values.
This tries to make the code as clear as possible pending a more comprehensive
rewrite.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14049
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14049
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Tue Aug 27 01:16:33 UTC 2019 on sn-devel-184
This is a macro that sets the pointer to NULL after the talloc_free()
and is part of our standard coding practices.
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Thankfully this only fails if the DB is corrupt and has a duplicate record.
The test was at the wrong end of the loop, and was for the
wrong boundary condition. A write after the end of the array would
occour before the condition was hit.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=13695
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
In case of a failing talloc_realloc(), the only reference
to the originally allocated memory is overwritten.
Instead use a temp var until success is verified.
Signed-off-by: Swen Schillig <swen@linux.ibm.com>
Reviewed-by: Christof Schmitt <cs@samba.org>
Reviewed-by: Matthias Dieter Wallnöfer <mdw@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
If you try to add a dn to itself, it expands as it goes. The resulting
loop cannot end well.
It looks like this in Python:
dn = ldb.Dn(ldb.Ldb(), 'CN=y,DC=x')
dn.add_base(dn)
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
This is needed for modules to access the ldb->options array, as this in in ldb_private.h
Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Flag is used to enforce binary encoded attribute values per attribute.
Signed-off-by: Björn Baumbach <bb@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Copy the options supplied to to ldb_connect, and place them on the
ldb_context. This allows backend options i.e. lmbd map size to be passed
cleanly from the callers.
Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Fixes:
lib/ldb/common/ldb.c:1091:3: warning: Value stored to 'ret' is never read <--[clang]
ret = 0;
^ ~
1 warning generated.
Signed-off-by: Noel Power <noel.power@suse.com>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Calling the "ldb_parse_tree" function with a filter consisting of
exactly a single space (" ") would trigger a read beyond the input
buffer. A unittest is included.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=13900
Signed-off-by: Michael Hanselmann <public@hansmi.ch>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Tim Beale <timbeale@catalyst.net.nz>
Pack function for new pack format with values separated from other data
so that while unpacking, the value section (which is probably large)
doesn't have to be loaded into cache/memory.
The new format is disabled for now.
Two tests are added that operate on a detailed binary breakdown of the
new format.
NOTE: Configure with --abi-check-disable to build this commit. This
patch is part of a set of LDB ABI changes, and the version update is
done on the last commit.
Signed-off-by: Aaron Haslett <aaronhaslett@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Unpack function for new pack format with values separated from other
data so that while unpacking, the value section (which is probably large)
doesn't have to be loaded into cache/memory.
Additionally, width of length field can now vary per-element to save space.
The old unpack routine is still present and is called if the old pack
format version number is found.
LDB torture suite is modified to run relevant tests on both old and new
pack format.
NOTE: Configure with --abi-check-disable to build this commit. This
patch is part of a set of LDB ABI changes, and the version update is
done on the last commit.
Signed-off-by: Aaron Haslett <aaronhaslett@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Since we're about to introduce a new packing format, it's a good time to
improve our code style and change some magic numbers into explicit
constants.
Signed-off-by: Aaron Haslett <aaronhaslett@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Replacing push and pull functions (which may cause issues with Undefined
Sanitizer) with Andreas Schneider's excellent macros which are a work in
progress and not yet merged into master. Once his work is upstream, I'll
rebase and change this code to import his headers.
Signed-off-by: Aaron Haslett <aaronhaslett@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
We will be adding a new packing format in forthcoming commits and there
may be more versions in the future. We need to make sure the database
contains records in a format we know how to read and write.
Done by fetching the @BASEINFO record and reading the first 4
bytes which contain the packing format version.
NOTE: Configure with --abi-check-disable to build this commit. This
patch is part of a set of LDB ABI changes, and the version update is
done on the last commit.
Signed-off-by: Aaron Haslett <aaronhaslett@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Unpack functions currently take an attribute list to restrict the set of
attributes to be returned in the constructed message. This
functionality is never used and complicates implementation of
forthcoming new pack format. This patch removes that functionality.
Using the unpack function then filtering the result turns
out not to be any slower.
NOTE: Configure with --abi-check-disable to build this commit. This
patch is part of a set of LDB ABI changes, and the version update is
done on the last commit.
Signed-off-by: Aaron Haslett <aaronhaslett@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
This patch moves ldb_kv's filter code into the pack code to replace
'only attr list' functionality which will be removed in forthcoming
commit. Unpacking data then filtering the result is not any slower
than the removed 'only attr list' approach.
'only attr list' test repurposed to test unpack -> filter flow.
NOTE: Configure with --abi-check-disable to build this commit. This
patch is part of a set of LDB ABI changes, and the version update is
done on the last commit.
Signed-off-by: Aaron Haslett <aaronhaslett@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Making unpack flag LDB_UNPACK_DATA_FLAG_NO_DATA_ALLOC required
behaviour, since allocating data during unpack is slow and unnecessary
in all current usages. In any future unpack usage, if editing of
returned memory is required, some function that duplicates the message
should be used, such as one of the filter_attrs functions, or msg_copy.
Signed-off-by: Aaron Haslett <aaronhaslett@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Previously we half-heartedly checked one end.
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
ldb_msg_new() is currently the same as talloc_zero(), but it might
not always be.
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
We had to devise our own scheme for writing integers in a human readable
format which also sorted correctly numerically. This might look a bit
confusing to outsiders, so here's a large comment as a peace offering.
Pair-programmed-with: Tim Beale <timbeale@catalyst.net.nz>
Signed-off-by: Garming Sam <garming@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
