The recently added TLS client session cache used
SSL_SESSION_is_resumable() to avoid polluting the cache with
non-resumable sessions. However, it turned out that we cannot provide
a shim for this function across the whole range of OpenSSL versions
due to the fact that OpenSSL 1.1.0 does uses opaque pointers for
SSL_SESSION objects.
The commit replaces the shim for SSL_SESSION_is_resumable() with a non
public approximation of it on systems shipped with OpenSSL 1.1.0. It
is not turned into a proper shim because it does not fully emulate the
behaviour of SSL_SESSION_is_resumable(), but in our case it is good
enough, as it still helps to protect the cache from pollution.
For systems shipped with OpenSSL 1.0.X and derivatives (e.g. older
versions of LibreSSL), the provided replacement perfectly mimics the
function it is intended to replace.
This commit extends TLS context cache with TLS client session cache so
that an associated session cache can be stored alongside the TLS
context within the context cache.
This commit adds an implementation of a client TLS session cache. TLS
client session cache is an object which allows efficient storing and
retrieval of previously saved TLS sessions so that they can be
resumed. This object is supposed to be a foundation for implementing
TLS session resumption - a standard technique to reduce the cost of
re-establishing a connection to the remote server endpoint.
OpenSSL does server-side TLS session caching transparently by
default. However, on the client-side, a TLS session to resume must be
manually specified when establishing the TLS connection. The TLS
client session cache is precisely the foundation for that.
The implementation is done on top of the reference counting
functionality found in OpenSSL/LibreSSL, which allows for avoiding
wrapping the object.
Adding this function allows using reference counting for TLS contexts
in BIND 9's codebase.
Previously, the isc_ht API would always take the key as a literal input
to the hashing function. Change the isc_ht_init() function to take an
'options' argument, in which ISC_HT_CASE_SENSITIVE or _INSENSITIVE can
be specified, to determine whether to use case-sensitive hashing in
isc_hash32() when hashing the key.
This commit adds support for keeping CA certificates stores associated
with TLS contexts. The intention is to keep one reusable store per a
set of related TLS contexts.
This commit adds a set of functions that can be used to implement
Strict and Mutual TLS:
* isc_tlsctx_load_client_ca_names();
* isc_tlsctx_load_certificate();
* isc_tls_verify_peer_result_string();
* isc_tlsctx_enable_peer_verification().
This commit adds a set of high-level utility functions to manipulate
the certificate stores. The stores are needed to implement TLS
certificates verification efficiently.
Previously, the unreachable code paths would have to be tagged with:
INSIST(0);
ISC_UNREACHABLE();
There was also older parts of the code that used comment annotation:
/* NOTREACHED */
Unify the handling of unreachable code paths to just use:
UNREACHABLE();
The UNREACHABLE() macro now asserts when reached and also uses
__builtin_unreachable(); when such builtin is available in the compiler.
The C17 standard deprecated ATOMIC_VAR_INIT() macro (see [1]). Follow
the suite and remove the ATOMIC_VAR_INIT() usage in favor of simple
assignment of the value as this is what all supported stdatomic.h
implementations do anyway:
* MacOSX.plaform: #define ATOMIC_VAR_INIT(__v) {__v}
* Gcc stdatomic.h: #define ATOMIC_VAR_INIT(VALUE) (VALUE)
1. http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1138r0.pdf
Previously, the function(s) in the commit subject could fail for various
reasons - mostly allocation failures, or other functions returning
different return code than ISC_R_SUCCESS. Now, the aforementioned
function(s) cannot ever fail and they would always return ISC_R_SUCCESS.
Change the function(s) to return void and remove the extra checks in
the code that uses them.
TLS clients can have their clock a short time in the past which will
result in not being able to validate the certificate.
Setting the "not before" property 5 minutes in the past will
accommodate with some possible clock skew across systems.
Clients can cache the TLS certificates and refuse to accept
another one with the same serial number from the same issuer.
Generate a random serial number for the self-signed certificates
instead of using a fixed value.
GnuTLS, NSS, and possibly other TLS libraries currently fail to work
with compressed point conversion form supported by OpenSSL.
Use uncompressed point conversion form for better compatibility.
This commit converts the license handling to adhere to the REUSE
specification. It specifically:
1. Adds used licnses to LICENSES/ directory
2. Add "isc" template for adding the copyright boilerplate
3. Changes all source files to include copyright and SPDX license
header, this includes all the C sources, documentation, zone files,
configuration files. There are notes in the doc/dev/copyrights file
on how to add correct headers to the new files.
4. Handle the rest that can't be modified via .reuse/dep5 file. The
binary (or otherwise unmodifiable) files could have license places
next to them in <foo>.license file, but this would lead to cluttered
repository and most of the files handled in the .reuse/dep5 file are
system test files.
For consistency with similar functions, rename `pcache` to `cachep`,
call a separate destroy function when references reach 0, and add
a missing call to isc_refcount_destroy().
This commit adds a TLS context object cache implementation. The
intention of having this object is manyfold:
- In the case of client-side contexts: allow reusing the previously
created contexts to employ the context-specific TLS session resumption
cache. That will enable XoT connection to be reestablished faster and
with fewer resources by not going through the full TLS handshake
procedure.
- In the case of server-side contexts: reduce the number of contexts
created on startup. That could reduce startup time in a case when
there are many "listen-on" statements referring to a smaller amount of
`tls` statements, especially when "ephemeral" certificates are
involved.
- The long-term goal is to provide in-memory storage for additional
data associated with the certificates, like runtime
representation (X509_STORE) of intermediate CA-certificates bundle for
Strict TLS/Mutual TLS ("ca-file").
The SSL_CTX_set_keylog_callback() function is a fairly recent OpenSSL
addition, having first appeared in version 1.1.1. Add a configure.ac
check for the availability of that function to prevent build errors on
older platforms. Sort similar checks alphabetically.
This makes the SSLKEYLOGFILE mechanism a silent no-op on unsupported
platforms, which is considered acceptable for a debugging feature.
Generate log messages containing TLS pre-master secrets when the
SSLKEYLOGFILE environment variable is set. This only ensures such
messages are prepared using the right logging category and passed to
libisc for further processing.
The TLS pre-master secret logging callback needs to be set on a
per-context basis, so ensure it happens for both client-side and
server-side TLS contexts.
ECDSA P-256 performs considerably better than the previously used
4096-bit RSA (can be observed using `openssl speed`), and, according
to RFC 6605, provides a security level comparable to 3072-bit RSA.
There was a logical bug when setting a list of enabled TLS protocols,
which may lead to a crash (an abort()) on systems with ancient OpenSSL
versions.
The problem was due to the fact that we were INSIST()ing on supporting
all of the TLS versions, while checking only for mentioned in the
configuration was implied.
This prevents a direct leak in OPENSSL_init_crypto (called from
OPENSSL_init_ssl).
Add shim version of OPENSSL_cleanup because it is missing in LibreSSL on
OpenBSD.
Unless being configured with the `no-deprecated` option, OpenSSL 3.0.0
still has the deprecated APIs present and will throw warnings during
compilation, when using them.
Make sure that the old APIs are being used only with the older versions
of OpenSSL.
This commit adds the ability to enable or disable stateless TLS
session resumption tickets (see RFC5077). Having this ability is
twofold.
Firstly, these tickets are encrypted by the server, and the algorithm
might be weaker than the algorithm negotiated during the TLS session
establishment (it is in general the case for TLSv1.2, but the generic
principle applies to TLSv1.3 as well, despite it having better ciphers
for session tickets). Thus, they might compromise Perfect Forward
Secrecy.
Secondly, disabling it might be necessary if the same TLS key/cert
pair is supposed to be used by multiple servers to achieve, e.g., load
balancing because the session ticket by default gets generated in
runtime, while to achieve successful session resumption ability, in
this case, would have required using a shared key.
The proper alternative to having the ability to disable stateless TLS
session resumption tickets is to implement a proper session tickets
key rollover mechanism so that key rotation might be performed
often (e.g. once an hour) to not compromise forward secrecy while
retaining the associated performance benefits. That is much more work,
though. On the other hand, having the ability to disable session
tickets allows having a deployable configuration right now in the
cases when either forward secrecy is wanted or sharing the TLS
key/cert pair between multiple servers is needed (or both).
This commit adds support for enforcing the preference of server
ciphers over the client ones. This way, the server attains control
over the ciphers priority and, thus, can choose more strong cyphers
when a client prioritises less strong ciphers over the more strong
ones, which is beneficial when trying to achieve Perfect Forward
Secrecy.
This commit adds support for setting TLS cipher list string in the
format specified in the OpenSSL
documentation (https://www.openssl.org/docs/man1.1.1/man1/ciphers.html).
The syntax of the cipher list is verified so that specifying the wrong
string will prevent the configuration from being loaded.
This commit adds support for loading DH-parameters (Diffie-Hellman
parameters) via the new "dhparam-file" option within "tls" clause. In
particular, Diffie-Hellman parameters are needed to enable the range
of forward-secrecy enabled cyphers for TLSv1.2, which are getting
silently disabled otherwise.
This commit adds the ability to specify allowed TLS protocols versions
within the "tls" clause. If an unsupported TLS protocol version is
specified in a file, the configuration file will not pass
verification.
Also, this commit adds strict checks for "tls" clauses verification,
in particular:
- it ensures that loading configuration files containing duplicated
"tls" clauses is not allowed;
- it ensures that loading configuration files containing "tls" clauses
missing "cert-file" or "key-file" is not allowed;
- it ensures that loading configuration files containing "tls" clauses
named as "ephemeral" or "none" is not allowed.
The ISC_MEM_DEBUGSIZE and ISC_MEM_DEBUGCTX did sanity checks on matching
size and memory context on the memory returned to the allocator. Those
will no longer needed when most of the allocator will be replaced with
jemalloc.
This commit adds two new autoconf options `--enable-doh` (enabled by
default) and `--with-libnghttp2` (mandatory when DoH is enabled).
When DoH support is disabled the library is not linked-in and support
for http(s) protocol is disabled in the netmgr, named and dig.
This commit fixes loading the certificate chain files so that the full
chain could be sent to the clients which require that for
verification. Before that fix only the top most certificate would be
loaded from the chain and sent to clients preventing some of them to
perform certificate validation (e.g. Windows 10 DoH client).
- style, cleanup, and removal of unnecessary code.
- combined isc_nm_http_add_endpoint() and isc_nm_http_add_doh_endpoint()
into one function, renamed isc_http_endpoint().
- moved isc_nm_http_connect_send_request() into doh_test.c as a helper
function; remove it from the public API.
- renamed isc_http2 and isc_nm_http2 types and functions to just isc_http
and isc_nm_http, for consistency with other existing names.
- shortened a number of long names.
- the caller is now responsible for determining the peer address.
in isc_nm_httpconnect(); this eliminates the need to parse the URI
and the dependency on an external resolver.
- the caller is also now responsible for creating the SSL client context,
for consistency with isc_nm_tlsdnsconnect().
- added setter functions for HTTP/2 ALPN. instead of setting up ALPN in
isc_tlsctx_createclient(), we now have a function
isc_tlsctx_enable_http2client_alpn() that can be run from
isc_nm_httpconnect().
- refactored isc_nm_httprequest() into separate read and send functions.
isc_nm_send() or isc_nm_read() is called on an http socket, it will
be stored until a corresponding isc_nm_read() or _send() arrives; when
we have both halves of the pair the HTTP request will be initiated.
- isc_nm_httprequest() is renamed isc__nm_http_request() for use as an
internal helper function by the DoH unit test. (eventually doh_test
should be rewritten to use read and send, and this function should
be removed.)
- added implementations of isc__nm_tls_settimeout() and
isc__nm_http_settimeout().
- increased NGHTTP2 header block length for client connections to 128K.
- use isc_mem_t for internal memory allocations inside nghttp2, to
help track memory leaks.
- send "Cache-Control" header in requests and responses. (note:
currently we try to bypass HTTP caching proxies, but ideally we should
interact with them: https://tools.ietf.org/html/rfc8484#section-5.1)
Instead of calling isc_tls_initialize()/isc_tls_destroy() explicitly use
gcc/clang attributes on POSIX and DLLMain on Windows to initialize and
shutdown OpenSSL library.
This resolves the issue when isc_nm_create() / isc_nm_destroy() was
called multiple times and it would call OpenSSL library destructors from
isc_nm_destroy().
At the same time, since we now have introduced the ctor/dtor for libisc,
this commit moves the isc_mem API initialization (the list of the
contexts) and changes the isc_mem_checkdestroyed() to schedule the
checking of memory context on library unload instead of executing the
code immediately.
Since we now require both libcrypto and libssl to be initialized for
netmgr, we move all the OpenSSL initialization code except the engine
initialization to isc_tls API.
The isc_tls_initialize() and isc_tls_destroy() has been made idempotent,
so they could be called multiple time. However when isc_tls_destroy()
has been called, the isc_tls_initialize() could not be called again.
This commit completes the support for DNS-over-HTTP(S) built on top of
nghttp2 and plugs it into the BIND. Support for both GET and POST
requests is present, as required by RFC8484.
Both encrypted (via TLS) and unencrypted HTTP/2 connections are
supported. The latter are mostly there for debugging/troubleshooting
purposes and for the means of encryption offloading to third-party
software (as might be desirable in some environments to simplify TLS
certificates management).
* Following the example set in 634bdfb16d8, the tlsdns netmgr
module now uses libuv and SSL primitives directly, rather than
opening a TLS socket which opens a TCP socket, as the previous
model was difficult to debug. Closes#2335.
* Remove the netmgr tls layer (we will have to re-add it for DoH)
* Add isc_tls API to wrap the OpenSSL SSL_CTX object into libisc
library; move the OpenSSL initialization/deinitialization from dstapi
needed for OpenSSL 1.0.x to the isc_tls_{initialize,destroy}()
* Add couple of new shims needed for OpenSSL 1.0.x
* When LibreSSL is used, require at least version 2.7.0 that
has the best OpenSSL 1.1.x compatibility and auto init/deinit
* Enforce OpenSSL 1.1.x usage on Windows
* Added a TLSDNS unit test and implemented a simple TLSDNS echo
server and client.
