Spotted by Mubin. This documentation relates to the code in
add_bus_environment() in bus/activation.c.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #275
Clients listening for a signal can match against the 'sender', expecting
it to come from a connection with a specific name. With this change,
dbus-send can send signals to them.
Instead of exposing _dbus_sha_test() as a private exported symbol,
we can expose _dbus_sha_compute(), which is the only thing called by
the test that isn't already exported.
Signed-off-by: Simon McVittie <smcv@collabora.com>
This lets us expose symbols in the embedded-tests build without
expanding the symbol table of the production library.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Some CI environments run build-time tests as root with CAP_AUDIT_WRITE.
In this case we need to close the audit socket so that it will not be
reported as leaked.
Signed-off-by: Simon McVittie <smcv@collabora.com>
The audit module is initialized every time a new BusContext is created,
which is only once in the real dbus-daemon, but can happen several times
in some unit tests.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Some CI systems do the entire build as uid 0 in a throwaway container.
If this is done in a build directory for which the messagebus user
does not have search (+x) permission, then they will be unable to
execute the just-built dbus-daemon binary.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Some CI systems do the build as root in a disposable container, and
run tests without ever having installed dbus. This means we can't
expect to be able to drop privileges from root to the DBUS_USER (usually
named messagebus or dbus) unless we have checked that the
DBUS_USER exists.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Some of these appear to hang, but making this diagnostic appear in the
log reveals the truth: it's just very slow.
Signed-off-by: Simon McVittie <smcv@collabora.com>
If we retry processing the message in response to OOM, but we don't
clear this buffer first, then the assertion at the beginning will fail.
Signed-off-by: Simon McVittie <smcv@collabora.com>
We don't actually complete successful authentication, because that
would require us to generate a cookie and compute the correct SHA1,
which is difficult to do in a deterministic authentication script.
However, we do assert that dbus#269 (CVE-2019-12749) has been fixed.
Signed-off-by: Simon McVittie <smcv@collabora.com>
The DBUS_COOKIE_SHA1 authentication mechanism aims to prove ownership
of a shared home directory by having the server write a secret "cookie"
into a .dbus-keyrings subdirectory of the desired identity's home
directory with 0700 permissions, and having the client prove that it can
read the cookie. This never actually worked for non-malicious clients in
the case where server uid != client uid (unless the server and client
both have privileges, such as Linux CAP_DAC_OVERRIDE or traditional
Unix uid 0) because an unprivileged server would fail to write out the
cookie, and an unprivileged client would be unable to read the resulting
file owned by the server.
Additionally, since dbus 1.7.10 we have checked that ~/.dbus-keyrings
is owned by the uid of the server (a side-effect of a check added to
harden our use of XDG_RUNTIME_DIR), further ruling out successful use
by a non-malicious client with a uid differing from the server's.
Joe Vennix of Apple Information Security discovered that the
implementation of DBUS_COOKIE_SHA1 was susceptible to a symbolic link
attack: a malicious client with write access to its own home directory
could manipulate a ~/.dbus-keyrings symlink to cause the DBusServer to
read and write in unintended locations. In the worst case this could
result in the DBusServer reusing a cookie that is known to the
malicious client, and treating that cookie as evidence that a subsequent
client connection came from an attacker-chosen uid, allowing
authentication bypass.
This is mitigated by the fact that by default, the well-known system
dbus-daemon (since 2003) and the well-known session dbus-daemon (in
stable releases since dbus 1.10.0 in 2015) only accept the EXTERNAL
authentication mechanism, and as a result will reject DBUS_COOKIE_SHA1
at an early stage, before manipulating cookies. As a result, this
vulnerability only applies to:
* system or session dbus-daemons with non-standard configuration
* third-party dbus-daemon invocations such as at-spi2-core (although
in practice at-spi2-core also only accepts EXTERNAL by default)
* third-party uses of DBusServer such as the one in Upstart
Avoiding symlink attacks in a portable way is difficult, because APIs
like openat() and Linux /proc/self/fd are not universally available.
However, because DBUS_COOKIE_SHA1 already doesn't work in practice for
a non-matching uid, we can solve this vulnerability in an easier way
without regressions, by rejecting it early (before looking at
~/.dbus-keyrings) whenever the requested identity doesn't match the
identity of the process hosting the DBusServer.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Closes: https://gitlab.freedesktop.org/dbus/dbus/issues/269
Closes: CVE-2019-12749
It wasn't immediately clear from the names of these method whether they
should return TRUE or FALSE for queued owners other than the primary
owner. Renaming them makes it obvious that the answer should be TRUE.
While I'm there, make the corresponding _dbus_verbose() messages more
precise.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Resolves: https://gitlab.freedesktop.org/dbus/dbus/issues/270
This adds a description of send_destination_prefix to the dbus-daemon manual.
Signed-off-by: Adrian Szyndela <adrian.s@samsung.com>
Change-Id: I46e6fa54ee34095c3ac83ec2c06cb91cf5669c7f
This adds a few tests for checking if activation is allowed
for names specified within send_destination_prefix namespaces.
Signed-off-by: Adrian Szyndela <adrian.s@samsung.com>
Change-Id: I7a5a66f82fc08ce6cb46e37de2c3dfae24d9ea67
This adds tests for mostly "send_destination_prefix" cases
and some "send_destination" cases.
The general test case is:
- addressed recipient is running and owns a name;
- a message is sent to the name owner;
- the response is checked for allow/deny (method return/error).
Each test case is executed both for primary and queued ownership.
The tests include:
- checking send allow/deny for names and namespaces, including nesting;
- checking send allow/deny for neighbour names;
- checking send allow/deny for names/namespaces+interface+member.
Signed-off-by: Adrian Szyndela <adrian.s@samsung.com>
Change-Id: If5fcada01601355e7aadefadad79c0b24f8c397f
This extends dbus-daemon with support for send_destination_prefix
attribute in XML policies.
It allows having policy rules for sending to bus names generated
within namespaces defined by a prefix. The similar behaviour can be
emulated by owning an additional name, not used for addressing messages,
as described in
https://lists.freedesktop.org/archives/dbus/2017-May/017188.html
However, introducing send_destination_prefix creates possibility
of communicating intentions in a more direct way, which is easier
to understand.
Signed-off-by: Adrian Szyndela <adrian.s@samsung.com>
Change-Id: I0016ad93f1c16b7742fef5f45ebaf01b55694d3c
This extracts a few lines of code and adds it as a DBusString function
that checks if a DBusString starts with words given with a C string
and a word separator. In other words, it checks if:
- a DBusString is a given C string, or
- a DBusString starts with a given C string and the next character is
a given word separator.
It is used for matching names to prefixes when checking the policy.
Signed-off-by: Adrian Szyndela <adrian.s@samsung.com>
Change-Id: Ie39d33916863d950dde38d3b8b20c8a539217302
CI builds intermittently fail with
error: Could not create output directory /.../doc/api/xml
or
error: Could not create output directory /.../doc/api/man
Fixes: https://gitlab.freedesktop.org/dbus/dbus/issues/266
Signed-off-by: Simon McVittie <smcv@collabora.com>
