This commit allows BIND 9 to be compiled with different flavours of
Userspace RCU, and improves the integration between Userspace RCU and
our event loop:
- In the RCU QSBR, the thread is put offline when polling and online
when rcu_dereference, rcu_assign_pointer (or friends) are called.
- In other RCU modes, we check that we are not reading when reaching the
quiescent callback in the event loop.
- We register the thread before uv_work_run() callback is called and
after it has finished. The rcu_(un)register_thread() has a large
overhead, but that's fine in this case.
The spinlock is small (atomic_uint_fast32_t at most), lightweight
synchronization primitive and should only be used for short-lived and
most of the time a isc_mutex should be used.
Add a isc_spinlock unit which is either (most of the time) a think
wrapper around pthread_spin API or an efficient shim implementation of
the simple spinlock.
This is an adaptation of my `hg64` experiments for use in BIND.
As well as renaming everything according to ISC style, I have
written some more extensive tests that ensure the edge cases are
correct and the fenceposts are in the right places.
I have added utility functions for working with precision in terms of
decimal significant figures as well as this code's native binary.
for testing purposes, we need to be able to specify a library path from
which to load the dnsrps implementation. this can now be done with the
"dnsrps-library" option.
DNSRPS can now be enabled in configure regardless of whether librpz.so
is currently installed on the system.
BIND needs a collection of standard lock-free data structures,
which we can find in liburcu, along with its RCU safe memory
reclamation machinery. We will use liburcu's QSBR variant instead
of the home-grown isc_qsbr.
Completely remove the TKEY Mode 2 (Diffie-Hellman Exchanged Keying) from
BIND 9 (from named, named.conf and all the tools). The TKEY usage is
fringe at best and in all known cases, GSSAPI is being used as it should.
The draft-eastlake-dnsop-rfc2930bis-tkey specifies that:
4.2 Diffie-Hellman Exchanged Keying (Deprecated)
The use of this mode (#2) is NOT RECOMMENDED for the following two
reasons but the specification is still included in Appendix A in case
an implementation is needed for compatibility with old TKEY
implementations. See Section 4.6 on ECDH Exchanged Keying.
The mixing function used does not meet current cryptographic
standards because it uses MD5 [RFC6151].
RSA keys must be excessively long to achieve levels of security
required by current standards.
We might optionally implement Elliptic Curve Diffie-Hellman (ECDH) key
exchange mode 6 if the draft ever reaches the RFC status. Meanwhile the
insecure DH mode needs to be removed.
`libirs` used to be a reference implementation of `getaddrinfo` and
related modern resolver APIs. It was stripped down in BIND 9.18
leaving only the `irs_resconf` module, which parses
`/etc/resolv.conf`. I have kept its include path and namespace prefix,
so it remains a little fragment of libirs now embedded in libdns.
Some compilers have a built-in definition of the _FORTIFY_SOURCE macro
that differs from BIND's preferred setting. This causes errors like
the one quoted below. The solution is to undefine the macro before
defining it. A similar fix was recently committed to glibc.
<command line>: error: '_FORTIFY_SOURCE' macro redefined
#define _FORTIFY_SOURCE 2
^
<built-in>: note: previous definition is here
#define _FORTIFY_SOURCE 0
^
https://sourceware.org/git/glibc.git/commitdiff/35bcb08eaa953c9b
Unfortunately, C still lacks a standard function for pause (x86,
sparc) or yeild (arm) instructions, for use in spin lock or CAS loops.
BIND has its own based on vendor intrinsics or inline asm.
Previously, it was buried in the `isc_rwlock` implementation. This
commit renames `isc_rwlock_pause()` to `isc_pause()` and moves
it into <isc/pause.h>.
This commit also fixes the configure script so that it detects ARM
yield support on systems that identify as `aarch*` instead of `arm*`.
On 64-bit ARM systems we now use the ISB (instruction synchronization
barrier) instruction in preference to yield. The ISB instruction
pauses the CPU for longer, several nanoseconds, which is more like the
x86 pause instruction. There are more details in a Rust pull request,
which also refers to MySQL making the same change:
https://github.com/rust-lang/rust/pull/84725
We don't need them in the repo, it's sufficient if we pregenerate them
while preparing the tarball. That way we don't have overhead while
modifying them but they are still available for installations without
Sphinx.
I assume that this will make rebases and cherry-picks across branches
easier, with less trial and error churn required in the CI.
It's implemented in the way that we build the manpages only when we
either have pregenerated pages available at the configure time or
sphinx-build is installed and working.
The implementation of UDP recvmmsg in libuv 1.35 and 1.36 is
incomplete and could cause assertion failure under certain
circumstances.
Modify the configure and runtime checks to report a fatal error when
trying to compile or run with the affected versions.
The --enable-dnsrps-dl switch for ./configure enables preparing a
DNSRPS-enabled build of BIND 9 that is not directly linked against a
DNSRPS provider library (dlopen() at runtime is used instead). Employ
this switch to test DNSRPS-enabled builds in the pairwise testing job in
GitLab CI.
Prefer the pthread_barrier implementation on platforms where it is
available over uv_barrier implementation. This also solves the problem
with thread sanitizer builds on macOS that doesn't have pthread barrier.
- Make it a separate opensslrsa_check_exponent_bits() function to
clean up the code a bit
- Always use provider API first if using openssl 3.0, and fallback
to EVP API for older openssl or if built with engine support
- Use RSA_get0_key() (with shim for openssl 1.0) to avoid memory
allocations
The small/large tuning has been completely removed from the code with
last remnant of the dead code in ns_interfacemgr. Remove the dead code
and the configure option.
While using mutrace, the phtread-rwlock based isc_rwlock implementation
would be all tracked in the rwlock.c unit losing all useful information
as all rwlocks would be traced in a single place. Rewrite the
pthread_rwlock based implementation to be header-only macros, so we can
use mutrace to properly track the rwlock contention without heavily
patching mutrace to understand the libisc synchronization primitives.
The dns_rbtdb unit already tracks the state of the node and tree rwlocks
during the top level function and passes the states of the locks to the
called functions.
Add the tree locking family of macros modeled after node locking macros,
and expand both to track the state of the lock in an external variable.
Additionally, in developer mode, add precondition to the macros, so the
lock is in required state - this should cause an assertion failure on
double locking instead of the thread getting stuck.
On Linux, the libcap is now mandatory. It makes things simpler for us.
System without {set,get}res{uid,gid} now have compatibility shim using
setreuid/setregid or seteuid/setegid to setup effective UID/GID, so the
same code can be called all the time (including on Linux).
The NetBSD system allocator is in fact based on the jemalloc, but it
doesn't export the extended interface, so we can't use that. Remove
the jemalloc enforcement for the NetBSD.
There's a known memory leak in the engine_pkcs11 at the time of writing
this and it interferes with the named ability to check for memory leaks
in the OpenSSL memory context by default.
Add an autoconf option to explicitly enable the memory leak detection,
and use it in the CI except for pkcs11 enabled builds. When this gets
fixed in the engine_pkc11, the option can be enabled by default.
Instead of using generic HAVE_BUILTIN_OVERFLOW, we need to check whether
the overflow functions actually work as there was a bug in GCC that it
would not detect mul overflow when compiled with `-m32` option without
optimizations and the bug was fixed only for GCC 6.5+ and 7.3+/8+.
For further details see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82274
By bumping the minimum libuv version to 1.34.0, it allows us to remove
all libuv shims we ever had and makes the code much cleaner. The
up-to-date libuv is available in all distributions supported by BIND
9.19+ either natively or as a backport.
previously, when ISC_BUFFER_USEINLINE was defined, macros were
used to implement isc_buffer primitives (isc_buffer_init(),
isc_buffer_region(), etc). these macros were missing the DbC
assertions for those primitives, which made it possible for
coding errors to go undetected.
adding the assertions to the macros caused compiler warnings on
some platforms. therefore, this commit converts the ISC__BUFFER
macros to static inline functions instead, with assertions included,
and eliminates the non-inline implementation from buffer.c.
the --enable-buffer-useinline configure option has been removed.
When jemalloc is the system allocator (on FreeBSD and NetBSD), trying
to build --without-jemalloc caused an obscure compiler error. Instead,
complain at configure time that --without-jemalloc cannot work. (It
needs to remain an error because it is vexing when configure quietly
ignores an explicit direction.)
When Address Sanitizer is enabled in gcc-11+, number of false positives
might appear like this:
netmgr/udp.c: In function 'isc__nm_udp_send':
netmgr/udp.c:729:13: warning: 'uv_udp_send' reading 16 bytes from a region of size 8 [-Wstringop-overread]
729 | r = uv_udp_send(&uvreq->uv_req.udp_send, &sock->uv_handle.udp,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
730 | &uvreq->uvbuf, 1, sa, udp_send_cb);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
netmgr/udp.c:729:13: note: referencing argument 3 of type 'const uv_buf_t[0]'
In file included from ./include/isc/uv.h:17,
from ./include/isc/barrier.h:31,
from netmgr/udp.c:17:
/usr/include/uv.h:711:15: note: in a call to function 'uv_udp_send'
711 | UV_EXTERN int uv_udp_send(uv_udp_send_t* req,
| ^~~~~~~~~~~
Disable the warning globally in the autoconf, instead of just locally in
a single CI job, as it might affect people outside our GitLab CI.
sd_notify() may be called by a service to notify the service manager
about state changes. It can be used to send arbitrary information,
encoded in an environment-block-like string. Most importantly, it can be
used for start-up completion notification.
Add libsystemd check to autoconf script and when the library is detected
add calls to sd_notify() around the server->reload_status changes.
Co-authored-by: Petr Špaček <pspacek@isc.org>
