Such fatal errors are reported by OpenSSL 1.1.1, and similarly by BoringSSL,
if application data is encountered during SSL shutdown, which started to be
observed on the second SSL_shutdown() call after SSL shutdown fixes made in
09fb2135a589 (1.19.2). The error means that the client continues to send
application data after receiving the "close_notify" alert (ticket #2318).
Previously it was reported as SSL_shutdown() error of SSL_ERROR_SYSCALL.
Chrome only uses TLS session tickets once with TLS 1.3, likely following
RFC 8446 Appendix C.4 recommendation. With OpenSSL, this works fine with
built-in session tickets, since these are explicitly renewed in case of
TLS 1.3 on each session reuse, but results in only two connections being
reused after an initial handshake when using ssl_session_ticket_key.
Fix is to always renew TLS session tickets in case of TLS 1.3 when using
ssl_session_ticket_key, similarly to how it is done by OpenSSL internally.
The SF_NOCACHE flag, introduced in FreeBSD 11 along with the new non-blocking
sendfile() implementation by glebius@, makes it possible to use sendfile()
along with the "directio" directive.
The variable contains a negotiated curve used for the handshake key
exchange process. Known curves are listed by their names, unknown
ones are shown in hex.
Note that for resumed sessions in TLSv1.2 and older protocols,
$ssl_curve contains the curve used during the initial handshake,
while in TLSv1.3 it contains the curve used during the session
resumption (see the SSL_get_negotiated_group manual page for
details).
The variable is only meaningful when using OpenSSL 3.0 and above.
With older versions the variable is empty.
Requires OpenSSL 3.0 compiled with "enable-ktls" option. Further, KTLS
needs to be enabled in kernel, and in OpenSSL, either via OpenSSL
configuration file or with "ssl_conf_command Options KTLS;" in nginx
configuration.
On FreeBSD, kernel TLS is available starting with FreeBSD 13.0, and
can be enabled with "sysctl kern.ipc.tls.enable=1" and "kldload ktls_ocf"
to load a software backend, see man ktls(4) for details.
On Linux, kernel TLS is available starting with kernel 4.13 (at least 5.2
is recommended), and needs kernel compiled with CONFIG_TLS=y (with
CONFIG_TLS=m, which is used at least on Ubuntu 21.04 by default,
the tls module needs to be loaded with "modprobe tls").
Export ciphers are forbidden to negotiate in TLS 1.1 and later protocol modes.
They are disabled since OpenSSL 1.0.2g by default unless explicitly configured
with "enable-weak-ssl-ciphers", and completely removed in OpenSSL 1.1.0.
A new behaviour was introduced in OpenSSL 1.1.1e, when a peer does not send
close_notify before closing the connection. Previously, it was to return
SSL_ERROR_SYSCALL with errno 0, known since at least OpenSSL 0.9.7, and is
handled gracefully in nginx. Now it returns SSL_ERROR_SSL with a distinct
reason SSL_R_UNEXPECTED_EOF_WHILE_READING ("unexpected eof while reading").
This leads to critical errors seen in nginx within various routines such as
SSL_do_handshake(), SSL_read(), SSL_shutdown(). The behaviour was restored
in OpenSSL 1.1.1f, but presents in OpenSSL 3.0 by default.
Use of the SSL_OP_IGNORE_UNEXPECTED_EOF option added in OpenSSL 3.0 allows
to set a compatible behaviour to return SSL_ERROR_ZERO_RETURN:
https://git.openssl.org/?p=openssl.git;a=commitdiff;h=09b90e0
See for additional details: https://github.com/openssl/openssl/issues/11381
The only consumer is a callback function for SSL_CTX_set_tmp_rsa_callback()
deprecated in OpenSSL 1.1.0. Now the function is conditionally compiled too.
The c->read->ready and c->write->ready flags might be reset during
the handshake, and not set again if the handshake was finished on
the other event. At the same time, some data might be read from
the socket during the handshake, so missing c->read->ready flag might
result in a connection hang, for example, when waiting for an SMTP
greeting (which was already received during the handshake).
Found by Sergey Kandaurov.
Recent fixes to SSL shutdown with lingering close (554c6ae25ffc, 1.19.5)
broke logging of SSL variables. To make sure logging of SSL variables
works properly, avoid freeing c->ssl when doing an SSL shutdown before
lingering close.
Reported by Reinis Rozitis
(http://mailman.nginx.org/pipermail/nginx/2021-May/060670.html).
Instead of calling SSL_free() with each return point, introduced a single
place where cleanup happens. As a positive side effect, this fixes two
potential memory leaks on ngx_handle_read_event() and ngx_handle_write_event()
errors where there were no SSL_free() calls (though unlikely practical,
as errors there are only expected to happen due to bugs or kernel issues).
Now "s", "V", and "v" format specifiers may be prefixed with "x" (lowercase)
or "X" (uppercase) to output corresponding data in hexadecimal format.
In collaboration with Maxim Dounin.
In some cases it might be needed to reject SSL handshake based on SNI
server name provided, for example, to make sure an invalid certificate
is not returned to clients trying to contact a name-based virtual server
without SSL configured. Previously, a "ssl_ciphers aNULL;" was used for
this. This workaround, however, is not compatible with TLSv1.3, in
particular, when using BoringSSL, where it is not possible to configure
TLSv1.3 ciphers at all.
With this change, the ssl_reject_handshake directive is introduced,
which instructs nginx to reject SSL handshakes with an "unrecognized_name"
alert in a particular server block.
For example, to reject handshake with names other than example.com,
one can use the following configuration:
server {
listen 443 ssl;
ssl_reject_handshake on;
}
server {
listen 443 ssl;
server_name example.com;
ssl_certificate example.com.crt;
ssl_certificate_key example.com.key;
}
The following configuration can be used to reject all SSL handshakes
without SNI server name provided:
server {
listen 443 ssl;
ssl_reject_handshake on;
}
server {
listen 443 ssl;
server_name ~^;
ssl_certificate example.crt;
ssl_certificate_key example.key;
}
Additionally, the ssl_reject_handshake directive makes configuring
certificates for the default server block optional. If no certificates
are configured in the default server for a given listening socket,
certificates must be defined in all non-default server blocks with
the listening socket in question.
With the ssl_conf_command directive it is now possible to set
arbitrary OpenSSL configuration parameters as long as nginx is compiled
with OpenSSL 1.0.2 or later. Full list of available configuration
commands can be found in the SSL_CONF_cmd manual page
(https://www.openssl.org/docs/man1.1.1/man3/SSL_CONF_cmd.html).
In particular, this allows configuring PrioritizeChaCha option
(ticket #1445):
ssl_conf_command Options PrioritizeChaCha;
It can be also used to configure TLSv1.3 ciphers in OpenSSL,
which fails to configure them via the SSL_CTX_set_cipher_list()
interface (ticket #1529):
ssl_conf_command Ciphersuites TLS_CHACHA20_POLY1305_SHA256;
Configuration commands are applied after nginx own configuration
for SSL, so they can be used to override anything set by nginx.
Note though that configuring OpenSSL directly with ssl_conf_command
might result in a behaviour nginx does not expect, and should be
done with care.
This fixes "SSL_shutdown() failed (SSL: ... bad write retry)" errors
as observed on the second SSL_shutdown() call after SSL shutdown fixes in
09fb2135a589 (1.19.2), notably when HTTP/2 connections are closed due
to read timeouts while there are incomplete writes.
This fixes "SSL_shutdown() failed (SSL: ... bad write retry)" errors
as observed on the second SSL_shutdown() call after SSL shutdown fixes in
09fb2135a589 (1.19.2), notably when sending fails in ngx_http_test_expect(),
similarly to ticket #1194.
Note that there are some places where c->error is misused to prevent
further output, such as ngx_http_v2_finalize_connection() if there
are pending streams, or in filter finalization. These places seem
to be extreme enough to don't care about missing shutdown though.
For example, filter finalization currently prevents keepalive from
being used.
The c->read->ready and c->write->ready flags need to be cleared to ensure
that appropriate read or write events will be reported by kernel. Without
this, SSL shutdown might wait till the timeout after blocking on writing
or reading even if there is a socket activity.
OpenSSL 1.1.1 fails to return SSL_ERROR_SYSCALL if an error happens
during SSL_write() after close_notify alert from the peer, and returns
SSL_ERROR_ZERO_RETURN instead. Broken by this commit, which removes
the "i == 0" check around the SSL_RECEIVED_SHUTDOWN one:
https://git.openssl.org/?p=openssl.git;a=commitdiff;h=8051ab2
In particular, if a client closed the connection without reading
the response but with properly sent close_notify alert, this resulted in
unexpected "SSL_write() failed while ..." critical log message instead
of correct "SSL_write() failed (32: Broken pipe)" at the info level.
Since SSL_ERROR_ZERO_RETURN cannot be legitimately returned after
SSL_write(), the fix is to convert all SSL_ERROR_ZERO_RETURN errors
after SSL_write() to SSL_ERROR_SYSCALL.
Previously, bidirectional shutdown never worked, due to two issues
in the code:
1. The code only tested SSL_ERROR_WANT_READ and SSL_ERROR_WANT_WRITE
when there was an error in the error queue, which cannot happen.
The bug was introduced in an attempt to fix unexpected error logging
as reported with OpenSSL 0.9.8g
(http://mailman.nginx.org/pipermail/nginx/2008-January/003084.html).
2. The code never called SSL_shutdown() for the second time to wait for
the peer's close_notify alert.
This change fixes both issues.
Note that after this change bidirectional shutdown is expected to work for
the first time, so c->ssl->no_wait_shutdown now makes a difference. This
is not a problem for HTTP code which always uses c->ssl->no_wait_shutdown,
but might be a problem for stream and mail code, as well as 3rd party
modules.
To minimize the effect of the change, the timeout, which was used to be 30
seconds and not configurable, though never actually used, is now set to
3 seconds. It is also expanded to apply to both SSL_ERROR_WANT_READ and
SSL_ERROR_WANT_WRITE, so timeout is properly set if writing to the socket
buffer is not possible.
Using SSL_CTX_set_verify(SSL_VERIFY_PEER) implies that OpenSSL will
send a certificate request during an SSL handshake, leading to unexpected
certificate requests from browsers as long as there are any client
certificates installed. Given that ngx_ssl_trusted_certificate()
is called unconditionally by the ngx_http_ssl_module, this affected
all HTTPS servers. Broken by 699f6e55bbb4 (not released yet).
Fix is to set verify callback in the ngx_ssl_trusted_certificate() function
without changing the verify mode.
This ensures that certificate verification is properly logged to debug
log during upstream server certificate verification. This should help
with debugging various certificate issues.
OCSP validation for client certificates is enabled by the "ssl_ocsp" directive.
OCSP responder can be optionally specified by "ssl_ocsp_responder".
When session is reused, peer chain is not available for validation.
If the verified chain contains certificates from the peer chain not available
at the server, validation will fail.
For ngx_http_process_request() part to work, this required to set both
r->http_connection->ssl and c->ssl on a QUIC stream. To avoid damaging
global SSL object, ngx_ssl_shutdown() is managed to ignore QUIC streams.
Introduced ngx_quic_input() and ngx_quic_output() as interface between
nginx and protocol. They are the only functions that are exported.
While there, added copyrights.
Previous change 1ce3f01a4355 incorrectly introduced processing of the
ngx_posted_next_events queue at the end of operation, effectively making
posted next events a nop, since at the end of an event loop iteration
the queue is always empty. Correct approach is to move events to the
ngx_posted_events queue at an iteration start, as it was done previously.
Further, in some cases the c->read event might be already in the
ngx_posted_events queue, and calling ngx_post_event() with the
ngx_posted_next_events queue won't do anything. To make sure the event
will be correctly placed into the ngx_posted_next_events queue
we now check if it is already posted.
Introduced in 9d2ad2fb4423 available bytes handling in SSL relied
on connection read handler being overwritten to set the ready flag
and the amount of available bytes. This approach is, however, does
not work properly when connection read handler is changed, for example,
when switching to a next pipelined request, and can result in unexpected
connection timeouts, see here:
http://mailman.nginx.org/pipermail/nginx-devel/2019-December/012825.html
Fix is to introduce ngx_event_process_posted_next() instead, which
will set ready and available regardless of how event handler is set.
Added code to track number of bytes available in the socket.
This makes it possible to avoid looping for a long time while
working with fast enough peer when data are added to the socket buffer
faster than we are able to read and process data.
When kernel does not provide number of bytes available, it is
retrieved using ioctl(FIONREAD) as long as a buffer is filled by
SSL_read().
It is assumed that number of bytes returned by SSL_read() is close
to the number of bytes read from the socket, as we do not use
SSL compression. But even if it is not true for some reason, this
is not important, as we post an additional reading event anyway.
Note that data can be buffered at SSL layer, and it is not possible
to simply stop reading at some point and wait till the event will
be reported by the kernel again. This can be only done when there
are no data in SSL buffers, and there is no good way to find out if
it's the case.
Instead of trying to figure out if SSL buffers are empty, this patch
introduces events posted for the next event loop iteration - such
events will be processed only on the next event loop iteration,
after going into the kernel and retrieving additional events. This
seems to be simple and reliable approach.
As long as there are data to read in the socket, yet the amount of data
is less than total size of the buffers in the chain, this saves one
unneeded read() syscall. Before this change, reading only stopped if
ngx_ssl_recv() returned no data, that is, two read() syscalls in a row
returned EAGAIN.
If X509_get_issuer_name() or X509_get_subject_name() returned NULL,
this could lead to a certificate reference leak. It cannot happen
in practice though, since each function returns an internal pointer
to a mandatory subfield of the certificate successfully decoded by
d2i_X509() during certificate message processing (closes#1751).
This makes it possible to provide certificates directly via variables
in ssl_certificate / ssl_certificate_key directives, without using
intermediate files.
It was accidentally introduced in 77436d9951a1 (1.15.9). In MSVC 2015
and more recent MSVC versions it triggers warning C4456 (declaration of
'pkey' hides previous local declaration). Previously, all such warnings
were resolved in 2a621245f4cf.
Reported by Steve Stevenson.
The SSL_OP_NO_CLIENT_RENEGOTIATION option was introduced in LibreSSL 2.5.1.
Unlike OpenSSL's SSL_OP_NO_RENEGOTIATION, it only disables client-initiated
renegotiation, and hence can be safely used on all SSL contexts.
Notably this affects various allocation errors, and should generally
improve things if an allocation error actually happens during a callback.
Depending on the OpenSSL version, returning an error can result in
either SSL_R_CALLBACK_FAILED or SSL_R_CLIENTHELLO_TLSEXT error from
SSL_do_handshake(), so both errors were switched to the "info" level.
Dynamic certificates re-introduce problem with incorrect session
reuse (AKA "virtual host confusion", CVE-2014-3616), since there are
no server certificates to generate session id context from.
To prevent this, session id context is now generated from ssl_certificate
directives as specified in the configuration. This approach prevents
incorrect session reuse in most cases, while still allowing sharing
sessions across multiple machines with ssl_session_ticket_key set as
long as configurations are identical.
Passwords have to be copied to the configuration pool to be used
at runtime. Also, to prevent blocking on stdin (with "daemon off;")
an empty password list is provided.
To make things simpler, password handling was modified to allow
an empty array (with 0 elements and elts set to NULL) as an equivalent
of an array with 1 empty password.
This makes it possible to reuse certificate loading at runtime,
as introduced in the following patches.
Additionally, this improves error logging, so nginx will now log
human-friendly messages "cannot load certificate" instead of only
referring to sometimes cryptic names of OpenSSL functions.
The "(SSL:)" snippet currently appears in logs when nginx code uses
ngx_ssl_error() to log an error, but OpenSSL's error queue is empty.
This can happen either because the error wasn't in fact from OpenSSL,
or because OpenSSL did not indicate the error in the error queue
for some reason.
In particular, currently "(SSL:)" can be seen in errors at least in
the following cases:
- When SSL_write() fails due to a syscall error,
"[info] ... SSL_write() failed (SSL:) (32: Broken pipe)...".
- When loading a certificate with no data in it,
"[emerg] PEM_read_bio_X509_AUX(...) failed (SSL:)".
This can easily happen due to an additional empty line before
the end line, so all lines of the certificate are interpreted
as header lines.
- When trying to configure an unknown curve,
"[emerg] SSL_CTX_set1_curves_list("foo") failed (SSL:)".
Likely there are other cases as well.
With this change, "(SSL:...)" will be only added to the error message
if there is something in the error queue. This is expected to make
logs more readable in the above cases. Additionally, with this change
it is now possible to use ngx_ssl_error() to log errors when some
of the possible errors are not from OpenSSL and not expected to have
anything in the error queue.
Checking multiple errors at once is a bad practice, as in general
it is not guaranteed that an object can be used after the error.
In this particular case, checking errors after multiple allocations
can result in excessive errors being logged when there is no memory
available.
If SSL_write_early_data() returned SSL_ERROR_WANT_WRITE, stop further reading
using a newly introduced c->ssl->write_blocked flag, as otherwise this would
result in SSL error "ssl3_write_bytes:bad length". Eventually, normal reading
will be restored by read event posted from successful SSL_write_early_data().
While here, place "SSL_write_early_data: want write" debug on the path.
With maximum version explicitly set, TLSv1.3 will not be unexpectedly
enabled if nginx compiled with OpenSSL 1.1.0 (without TLSv1.3 support)
will be run with OpenSSL 1.1.1 (with TLSv1.3 support).
The "no suitable signature algorithm" errors are reported by OpenSSL 1.1.1
when using TLSv1.3 if there are no shared signature algorithms. In
particular, this can happen if the client limits available signature
algorithms to something we don't have a certificate for, or to an empty
list. For example, the following command:
openssl s_client -connect 127.0.0.1:8443 -sigalgs rsa_pkcs1_sha1
will always result in the "no suitable signature algorithm" error
as the "rsa_pkcs1_sha1" algorithm refers solely to signatures which
appear in certificates and not defined for use in TLS 1.3 handshake
messages.
The SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS error is what BoringSSL returns
in the same situation.
The "no suitable key share" errors are reported by OpenSSL 1.1.1 when
using TLSv1.3 if there are no shared groups (that is, elliptic curves).
In particular, it is easy enough to trigger by using only a single
curve in ssl_ecdh_curve:
ssl_ecdh_curve secp384r1;
and using a different curve in the client:
openssl s_client -connect 127.0.0.1:443 -curves prime256v1
On the client side it is seen as "sslv3 alert handshake failure",
"SSL alert number 40":
0:error:14094410:SSL routines:ssl3_read_bytes:sslv3 alert handshake failure:ssl/record/rec_layer_s3.c:1528:SSL alert number 40
It can be also triggered with default ssl_ecdh_curve by using a curve
which is not in the default list (X25519, prime256v1, X448, secp521r1,
secp384r1):
openssl s_client -connect 127.0.0.1:8443 -curves brainpoolP512r1
Given that many clients hardcode prime256v1, these errors might become
a common problem with TLSv1.3 if ssl_ecdh_curve is redefined. Previously
this resulted in not using ECDH with such clients, but with TLSv1.3 it
is no longer possible and will result in a handshake failure.
The SSL_R_NO_SHARED_GROUP error is what BoringSSL returns in the same
situation.
Seen at:
https://serverfault.com/questions/932102/nginx-ssl-handshake-error-no-suitable-key-share
Following 7319:dcab86115261, as long as SSL_OP_NO_RENEGOTIATION is
defined, it is OpenSSL library responsibility to prevent renegotiation,
so the checks are meaningless.
Additionally, with TLSv1.3 OpenSSL tends to report SSL_CB_HANDSHAKE_START
at various unexpected moments - notably, on KeyUpdate messages and
when sending tickets. This change prevents unexpected connection
close on KeyUpdate messages and when finishing handshake with upcoming
early data changes.
It is possible that after SSL_read() will return SSL_ERROR_WANT_WRITE,
further calls will return SSL_ERROR_WANT_READ without reading any
application data. We have to call ngx_handle_write_event() and
switch back to normal write handling much like we do if there are some
application data, or the write there will be reported again and again.
Similarly, we have to switch back to normal read handling if there
is saved read handler and SSL_write() returns SSL_ERROR_WANT_WRITE.
While SSL_read() most likely to return SSL_ERROR_WANT_WRITE (and SSL_write()
accordingly SSL_ERROR_WANT_READ) during an SSL renegotiation, it is
not necessary mean that a renegotiation was started. In particular,
it can never happen during a renegotiation or can happen multiple times
during a renegotiation.
Because of the above, misleading "peer started SSL renegotiation" info
messages were replaced with "SSL_read: want write" and "SSL_write: want read"
debug ones.
Additionally, "SSL write handler" and "SSL read handler" are now logged
by the SSL write and read handlers, to make it easier to understand that
temporary SSL handlers are called instead of normal handlers.
Early data AKA 0-RTT mode is enabled as long as "ssl_early_data on" is
specified in the configuration (default is off).
The $ssl_early_data variable evaluates to "1" if the SSL handshake
isn't yet completed, and can be used to set the Early-Data header as
per draft-ietf-httpbis-replay-04.
