While inserting a new entry into the dynamic table, first the entry is added,
and then older entries are evicted until table size is within capacity. After
the first step, the number of entries may temporarily exceed the maximum
calculated from capacity by one entry, which previously caused table overflow.
The easiest way to trigger the issue is to keep adding entries with empty names
and values until first eviction.
The issue was introduced by 987bee4363d1.
Previously a decoder stream was created on demand for sending Section
Acknowledgement, Stream Cancellation and Insert Count Increment. If conditions
for sending any of these instructions never happen, a decoder stream is not
created at all. These conditions include client not using the dynamic table and
no streams abandoned by server (RFC 9204, Section 2.2.2.2). However RFC 9204,
Section 4.2 defines only one condition for not creating a decoder stream:
An endpoint MAY avoid creating a decoder stream if its decoder sets
the maximum capacity of the dynamic table to zero.
The change enables pre-creation of the decoder stream at HTTP/3 session
initialization if maximum dynamic table capacity is not zero. Note that this
value is currently hardcoded to 4096 bytes and is not configurable, so the
stream is now always created.
Also, the change fixes a potential stack overflow when creating a decoder
stream in ngx_http_v3_send_cancel_stream() while draining a request stream by
ngx_drain_connections(). Creating a decoder stream involves calling
ngx_get_connection(), which calls ngx_drain_connections(), which will drain the
same request stream again. If client's MAX_STREAMS for uni stream is high
enough, these recursive calls will continue until we run out of stack.
Otherwise, decoder stream creation will fail at some point and the request
stream connection will be drained. This may result in use-after-free, since
this connection could still be referenced up the stack.
Previously chain links could sometimes be dropped instead of being reused,
which could result in increased memory consumption during long requests.
A similar chain link issue in ngx_http_gzip_filter_module was fixed in
da46bfc484ef (1.11.10).
Based on a patch by Sangmin Lee.
Using "long *" instead of "AO_t *" leads either to -Wincompatible-pointer-types
or -Wpointer-sign warnings, depending on whether long and size_t are compatible
types (e.g., ILP32 versus LP64 data models). Notably, -Wpointer-sign warnings
are enabled by default in Clang only, and -Wincompatible-pointer-types is an
error starting from GCC 14.
Signed-off-by: Edgar Bonet <bonet@grenoble.cnrs.fr>
Passing from udp was not possible for the most part due to preread buffer
restriction. Passing to udp could occasionally work, but the connection would
still be bound to the original listen rbtree, which prevented it from being
deleted on connection closure.
When loading certificate keys via ENGINE_load_private_key() in runtime,
it was possible to overwrite configuration on ENGINE_by_id() failure.
OpenSSL documention doesn't describe errors in details, the only reason
I found in the comment to example is when the engine is not available.
Previously, a request body larger than declared in Content-Length resulted in
a 413 status code, because Content-Length was mistakenly used as the maximum
allowed request body, similar to client_max_body_size. Following the HTTP/3
specification, such requests are now rejected with the 400 error as malformed.
The ngx_quic_run() function uses qc->close timer to limit the handshake
duration. Normally it is removed by ngx_quic_do_init_streams() which is
called once when we are done with initial SSL processing.
The problem happens when the client sends early data and streams are
initialized in the ngx_quic_run() -> ngx_quic_handle_datagram() call.
The order of set/remove timer calls is now reversed; the close timer is
set up and the timer fires when assigned, starting the unexpected connection
close process.
The fix is to skip setting the timer if streams were initialized during
handling of the initial datagram. The idle timer for quic is set anyway,
and stream-related timeouts are managed by application layer.
Notably, Apple Silicon CPUs have 128 byte cache line size,
which is twice the default configured for generic aarch64.
Signed-off-by: Piotr Sikora <piotr@aviatrix.com>
Previously, the response text wasn't initialized and the rewrite module
was sending response body set to NULL.
Found with UndefinedBehaviorSanitizer (pointer-overflow).
Signed-off-by: Piotr Sikora <piotr@aviatrix.com>
Previously, it could result when left-shifting signed integer due to implicit
integer promotion, such that the most significant bit appeared on the sign bit.
In practice, though, this results in the same left value as with an explicit
cast, at least on known compilers, such as GCC and Clang. The reason is that
in_addr_t, which is equivalent to uint32_t and same as "unsigned int" in ILP32
and LP64 data type models, has the same type width as the intermediate after
integer promotion, so there's no side effects such as sign-extension. This
explains why adding an explicit cast does not change object files in practice.
Found with UndefinedBehaviorSanitizer (shift).
Based on a patch by Piotr Sikora.
While copying ngx_http_variable_value_t structures to geo binary base
in ngx_http_geo_copy_values(), and similarly in the stream module,
uninitialized parts of these structures are copied as well. These
include the "escape" field and possible holes. Calculating crc32 of
this data triggers uninitialized memory access.
Found with MemorySanitizer.
Signed-off-by: Piotr Sikora <piotr@aviatrix.com>
In preparation for adding more parameters to the listen directive,
and to be in sync with the corresponding structure in the http module.
No functional changes.
Originally, the stream module was developed based on the mail module,
following the existing style. Then it was diverged to closely follow
the http module development. This change updates style to use sscf
naming convention troughout the stream module, which matches the http
module code style. No functional changes.
The module allows to pass connections from Stream to other modules such as HTTP
or Mail, as well as back to Stream. Previously, this was only possible with
proxying. Connections with preread buffer read out from socket cannot be
passed.
The module allows selective SSL termination based on SNI.
stream {
server {
listen 8000 default_server;
ssl_preread on;
...
}
server {
listen 8000;
server_name foo.example.com;
pass 127.0.0.1:8001; # to HTTP
}
server {
listen 8000;
server_name bar.example.com;
...
}
}
http {
server {
listen 8001 ssl;
...
location / {
root html;
}
}
}
Server name is taken either from ngx_stream_ssl_module or
ngx_stream_ssl_preread_module.
The change adds "default_server" parameter to the "listen" directive,
as well as the following directives: "server_names_hash_max_size",
"server_names_hash_bucket_size", "server_name" and "ssl_reject_handshake".
Previously, preread buffer was always read out from socket, which made it
impossible to terminate SSL on the connection without introducing additional
SSL BIOs. The following patches will rely on this.
Now, when possible, recv(MSG_PEEK) is used instead, which keeps data in socket.
It's called if SSL is not already terminated and if an egde-triggered event
method is used. For epoll, EPOLLRDHUP support is also required.
Stream connection cleanup handler ngx_quic_stream_cleanup_handler() calls
ngx_quic_shutdown_stream() after which it resets the pointer from quic stream
to the connection (sc->connection = NULL). Previously if this call failed,
sc->connection retained the old value, while the connection was freed by the
application code. This resulted later in a second attempt to close the freed
connection, which lead to allocator double free error.
The fix is to reset the sc->connection pointer in case of error.
Inspired by RFC 9001, Section 6.3, trial packet decryption with the current
keys is now used to avoid a timing side-channel signal. Further, this fixes
segfault while accessing missing next keys (ticket #2585).
Previously if an MTU probe send failed early in ngx_quic_frame_sendto()
due to allocation error or congestion control, the application level packet
number was not increased, but was still saved as MTU probe packet number.
Later when a packet with this number was acknowledged, the unsent MTU probe
was acknowledged as well. This could result in discovering a bigger MTU than
supported by the path, which could lead to EMSGSIZE (Message too long) errors
while sending further packets.
The problem existed since PMTUD was introduced in 58afcd72446f (1.25.2).
Back then only the unlikely memory allocation error could trigger it. However
in efcdaa66df2e congestion control was added to ngx_quic_frame_sendto() which
can now trigger the issue with a higher probability.
Now "fastopen", "backlog", "accept_filter", "deferred", and "so_keepalive"
parameters are not allowed with "quic" in the "listen" directive.
Reported by Izorkin.
When filter finalization is triggered when working with an upstream server,
and error_page redirects request processing to some simple handler,
ngx_http_request_finalize() triggers request termination when the response
is sent. In particular, via the upstream cleanup handler, nginx will close
the upstream connection and the corresponding socket.
Still, this can happen to be with ngx_event_pipe() on stack. While
the code will set p->downstream_error due to NGX_ERROR returned from the
output filter chain by filter finalization, otherwise the error will be
ignored till control returns to ngx_http_upstream_process_request().
And event pipe might try reading from the (already closed) socket, resulting
in "readv() failed (9: Bad file descriptor) while reading upstream" errors
(or even segfaults with SSL).
Such errors were seen with the following configuration:
location /t2 {
proxy_pass http://127.0.0.1:8080/big;
image_filter_buffer 10m;
image_filter resize 150 100;
error_page 415 = /empty;
}
location /empty {
return 204;
}
location /big {
# big enough static file
}
Fix is to clear p->upstream in ngx_http_upstream_finalize_request(),
and ensure that p->upstream is checked in ngx_event_pipe_read_upstream()
and when handling events at ngx_event_pipe() exit.
When a request was terminated due to an error via ngx_http_terminate_request()
while an AIO operation was running in a subrequest, various issues were
observed. This happened because ngx_http_request_finalizer() was only set
in the subrequest where ngx_http_terminate_request() was called, but not
in the subrequest where the AIO operation was running. After completion
of the AIO operation normal processing of the subrequest was resumed, leading
to issues.
In particular, in case of the upstream module, termination of the request
called upstream cleanup, which closed the upstream connection. Attempts to
further work with the upstream connection after AIO operation completion
resulted in segfaults in ngx_ssl_recv(), "readv() failed (9: Bad file
descriptor) while reading upstream" errors, or socket leaks.
In ticket #2555, issues were observed with the following configuration
with cache background update (with thread writing instrumented to
introduce a delay, when a client closes the connection during an update):
location = /background-and-aio-write {
proxy_pass ...
proxy_cache one;
proxy_cache_valid 200 1s;
proxy_cache_background_update on;
proxy_cache_use_stale updating;
aio threads;
aio_write on;
limit_rate 1000;
}
Similarly, the same issue can be seen with SSI, and can be caused by
errors in subrequests, such as in the following configuration
(where "/proxy" uses AIO, and "/sleep" returns 444 after some delay,
causing request termination):
location = /ssi-active-boom {
ssi on;
ssi_types *;
return 200 '
<!--#include virtual="/proxy" -->
<!--#include virtual="/sleep" -->
';
limit_rate 1000;
}
Or the same with both AIO operation and the error in non-active subrequests
(which needs slightly different handling, see below):
location = /ssi-non-active-boom {
ssi on;
ssi_types *;
return 200 '
<!--#include virtual="/static" -->
<!--#include virtual="/proxy" -->
<!--#include virtual="/sleep" -->
';
limit_rate 1000;
}
Similarly, issues can be observed with just static files. However,
with static files potential impact is limited due to timeout safeguards
in ngx_http_writer(), and the fact that c->error is set during request
termination.
In a simple configuration with an AIO operation in the active subrequest,
such as in the following configuration, the connection is closed right
after completion of the AIO operation anyway, since ngx_http_writer()
tries to write to the connection and fails due to c->error set:
location = /ssi-active-static-boom {
ssi on;
ssi_types *;
return 200 '
<!--#include virtual="/static-aio" -->
<!--#include virtual="/sleep" -->
';
limit_rate 1000;
}
In the following configuration, with an AIO operation in a non-active
subrequest, the connection is closed only after send_timeout expires:
location = /ssi-non-active-static-boom {
ssi on;
ssi_types *;
return 200 '
<!--#include virtual="/static" -->
<!--#include virtual="/static-aio" -->
<!--#include virtual="/sleep" -->
';
limit_rate 1000;
}
Fix is to introduce r->main->terminated flag, which is to be checked
by AIO event handlers when the r->main->blocked counter is decremented.
When the flag is set, handlers are expected to wake up the connection
instead of the subrequest (which might be already cleaned up).
Additionally, now ngx_http_request_finalizer() is always set in the
active subrequest, so waking up the connection properly finalizes the
request even if termination happened in a non-active subrequest.
Each AIO (thread IO) operation being run is now accompanied with 1-minute
timer. This timer prevents unexpected shutdown of the worker process while
an AIO operation is running, and logs an alert if the operation is running
for too long.
This fixes "open socket left" alerts during worker processes shutdown
due to pending AIO (or thread IO) operations while corresponding requests
have no timers. In particular, such errors were observed while reading
cache headers (ticket #2162), and with worker_shutdown_timeout.
When graceful shutdown was requested, and then nginx was forced to
do fast shutdown, it used to (incorrectly) complain about open sockets
left in connections which weren't yet closed when fast shutdown
was requested.
Fix is to avoid complaining about open sockets when fast shutdown was
requested after graceful one. Abnormal termination, if requested with
the WINCH signal, can still happen though.
OPENSSL_VERSION_NUMBER is now redefined to 0x1010000fL for LibreSSL 3.5.0
and above. Building with older LibreSSL versions, such as 2.8.0, may now
produce warnings (see cab37803ebb3) and may require appropriate compiler
options to suppress them.
Notably, this allows to start using SSL_get0_verified_chain() appeared
in OpenSSL 1.1.0 and LibreSSL 3.5.0, without additional macro tests.
Prodded by Ilya Shipitsin.
