As state in RFC9113#8.1, HEADERS frame with the ES flag set that carries an
informational status code is malformed. However, there is no test on this
condition.
On 2.4 and higher, it is hard to predict consequences of this bug because
end of the message is only reported with a flag. But on 2.2 and lower, it
leads to a crash because there is an unexpected extra EOM block at the end
of an interim response.
Now, when a ES flag is detected on a HEADERS frame for an interim message, a
stream error is sent (RST_STREAM/PROTOCOL_ERROR).
This patch should solve the issue #1972. It should be backported as far as
2.0.
Ensure calls to http_find_header() terminate. If a "Set-Cookie2"
header is found then the while(1) loop in
http_manage_server_side_cookies() will never terminate, resulting in
the watchdog firing and the process terminating via SIGABRT.
The while(1) loop becomes unbounded because an unmatched call to
http_find_header("Set-Cookie") will leave ctx->blk=NULL. Subsequent
calls to check for "Set-Cookie2" will now enumerate from the beginning
of all the blocks and will once again match on subsequent
passes (assuming a match first time around), hence the loop becoming
unbounded.
This issue was introduced with HTX and this fix should be backported
to all versions supporting HTX.
Many thanks to Grant Spence (gspence@redhat.com) for working through
this issue with me.
Willy Tarreau [Thu, 26 Aug 2021 14:23:37 +0000 (16:23 +0200)]
BUG/MAJOR: htx: fix missing header name length check in htx_add_header/trailer
Shachar Menashe for JFrog Security reported that htx_add_header() and
htx_add_trailer() were missing a length check on the header name. While
this does not allow to overwrite any memory area, it results in bits of
the header name length to slip into the header value length and may
result in forging certain header names on the input. The sad thing here
is that a FIXME comment was present suggesting to add the required length
checks :-(
The injected headers are visible to the HTTP internals and to the config
rules, so haproxy will generally stay synchronized with the server. But
there is one exception which is the content-length header field, because
it is already deduplicated on the input, but before being indexed. As
such, injecting a content-length header after the deduplication stage
may be abused to present a different, shorter one on the other side and
help build a request smuggling attack, or even maybe a response splitting
attack.
As a mitigation measure, it is sufficient to verify that no more than
one such header is present in any message, which is normally the case
thanks to the duplicate checks:
http-request deny if { req.hdr_cnt(content-length) gt 1 }
http-response deny if { res.hdr_cnt(content-length) gt 1 }
This must be backported to all HTX-enabled versions, hence as far as 2.0.
In 2.3 and earlier, the functions are in src/htx.c instead.
Many thanks to Shachar for his work and his responsible report!
[wt: code is in src/htx.c in 2.3 and older] Signed-off-by: Willy Tarreau <w@1wt.eu>
Gbp-Pq: Name 0001-2.0-2.3-BUG-MAJOR-htx-fix-missing-header-name-length-check-i.patch
Willy Tarreau [Thu, 19 Aug 2021 21:06:58 +0000 (23:06 +0200)]
[PATCH] BUG/MEDIUM: h2: match absolute-path not path-absolute for :path
RFC7540 states that :path follows RFC3986's path-absolute. However
that was a bug introduced in the spec between draft 04 and draft 05
of the spec, which implicitly causes paths starting with "//" to be
forbidden. HTTP/1 (and now HTTP core semantics) made it explicit
that the request-target in origin-form follows a purposely defined
absolute-path defined as 1*(/ segment) to explicitly allow "//".
http2bis now fixes this by relying on absolute-path so that "//"
becomes valid and matches other versions. Full discussion here:
This issue appeared in haproxy with commit 4b8852c70 ("BUG/MAJOR: h2:
verify that :path starts with a '/' before concatenating it") when
making the checks on :path fully comply with the spec, and was backported
as far as 2.0, so this fix must be backported there as well to allow
"//" in H2 again.
Willy Tarreau [Wed, 11 Aug 2021 13:39:13 +0000 (15:39 +0200)]
BUG/MEDIUM: h2: give :authority precedence over Host
The wording regarding Host vs :authority in RFC7540 is ambiguous as it
says that an intermediary must produce a host header from :authority if
Host is missing, but doesn't say anything regarding the possibility that
Host and :authority differ, which leaves Host with higher precedence
there. In addition it mentions that clients should use :authority
*instead* of Host, and that H1->H2 should use :authority only if the
original request was in authority form. This leaves some gray area in
the middle of the chain for fully valid H2 requests arboring a Host
header that are forwarded to the other side where it's possible to
drop the Host header and use the authority only after forwarding to a
second H2 layer, thus possibly seeing two different values of Host at
a different stage. There's no such issue when forwarding from H2 to H1
as the authority is dropped only only the Host is kept.
Note that the following request is sufficient to re-normalize such a
request:
http-request set-header host %[req.hdr(host)]
The new spec in progress (draft-ietf-httpbis-http2bis-03.html) addresses
this trouble by being a bit is stricter on these rules. It clarifies that
:authority must always be used instead of Host and that Host ought to be
ignored. This is much saner as it avoids to convey two distinct values
along the chain. This becomes the protocol-level equivalent of:
http-request set-uri %[url]
So this patch does exactly this, which we were initially a bit reluctant
to do initially by lack of visibiility about other implementation's
expectations. In addition it slightly simplifies the Host header field
creation by always placing it first in the list of headers instead of
last; this could speed up the look up a little bit.
This needs to be backported to 2.0. The legacy code there is a bit
different but not too much, the code can be simplified to simply
omit host during the copy and continue.
Willy Tarreau [Wed, 11 Aug 2021 09:12:46 +0000 (11:12 +0200)]
BUG/MAJOR: h2: enforce checks on the method syntax before translating to HTX
The situation with message components in H2 is always troubling. They're
produced by the HPACK layer which contains a dictionary of well-known
hardcoded values, yet wants to remain binary transparent and protocol-
agnostic with HTTP just being one user, yet at the H2 layer we're
supposed to enforce some checks on some selected pseudo-headers that
come from internal constants... The :method pseudo-header is no exception
and is not tested when coming from the HPACK layer. This makes it possible
to pass random chars into methods, that can be serialized on another H2
connection (where they would not harm), or worse, on an H1 connection
where they can be used to transform the forwareded request. This is
similar to the request line injection described here:
https://portswigger.net/research/http2
A workaround here is to reject malformed methods by placing this rule
in the frontend or backend, at least before leaving haproxy in H1:
http-request reject if { method -m reg [^A-Z0-9] }
Alternately H2 may be globally disabled by commenting out the "alpn"
directive on "bind" lines, and by rejecting H2 streams creation by
adding the following statement to the global section:
tune.h2.max-concurrent-streams 0
This patch adds a check for each character of the method to be part of
the ones permitted in a token, as mentioned in RFC7231#4.1. This should
be backported to versions 2.0 and above, maybe even 1.8. For older
versions not having HTX_FL_PARSING_ERROR, a "goto fail" works as well
as it results in a protocol error at the stream level. Non-HTX versions
were initially thought to be safe but must be carefully rechecked since
they transcode the request into H1 before processing it.
Willy Tarreau [Tue, 10 Aug 2021 14:30:55 +0000 (16:30 +0200)]
BUG/MAJOR: h2: verify that :path starts with a '/' before concatenating it
Tim Düsterhus found that while the H2 path is checked for non-emptiness,
invalid chars and '*', a test is missing to verify that except for '*',
it always starts with exactly one '/'. During the reconstruction of the
full URI when passing to HTX, this allows to affect the apparent authority
by appending a port number or a suffix name.
This only affects H2-to-H2 communications, as H2-to-H1 do not use the
authority. Like for previous fix, the following rule installed in the
frontend or backend is sufficient to renormalize the internal URI:
http-request set-header host %[req.hdr(host)]
This needs to be backported to 2.2, since earlier versions do not rebuild
a full URI using the authority and will fail on the malformed path at the
HTTP layer.
Willy Tarreau [Tue, 10 Aug 2021 13:37:34 +0000 (15:37 +0200)]
BUG/MAJOR: h2: verify early that non-http/https schemes match the valid syntax
While we do explicitly check for strict character sets in the scheme,
this is only done when extracting URL components from an assembled one,
and we have special handling for "http" and "https" schemes directly in
the H2-to-HTX conversion. Sadly, this lets all other ones pass through
if they start exactly with "http://" or "https://", allowing the
reconstructed URI to start with a different looking authority if it was
part of the scheme.
It's interesting to note that in this case the valid authority is in
the Host hedaer and that the request will only be wrong if emitted over
H2 on the backend side, since H1 will not emit an absolute URI by
default and will drop the scheme. So in essence, this is a variant of
the scheme-based attack described below in that it only affects H2-H2
and not H2-H1 forwarding:
https://portswigger.net/research/http2
As such, a simple workaround consists in just adding the following
rule in the frontend or backend, which will have for effect to
renormalize the authority in the request line according to the
concatenated version:
http-request set-uri %[url]
This patch simply adds the missing syntax checks for non-http/https
schemes before the concatenation in the H2 code. An improvement may
consist in the future in splitting these ones apart in the start
line so that only the "url" sample fetch function requires to access
them together and that all other places continue to access them
separately. This will then allow the core code to perform such checks
itself.
The patch needs to be backported as far as 2.2. Before 2.2 the full
URI was not being reconstructed so the scheme and authority part were
always dropped from H2 requests to leave only origin requests. Note
for backporters: this depends on this previous patch:
MINOR: http: add a new function http_validate_scheme() to validate a scheme
Many thanks to Tim Düsterhus for figuring that one and providing a
reproducer.
Willy Tarreau [Tue, 10 Aug 2021 13:35:36 +0000 (15:35 +0200)]
MINOR: http: add a new function http_validate_scheme() to validate a scheme
While http_parse_scheme() extracts a scheme from a URI by extracting
exactly the valid characters and stopping on delimiters, this new
function performs the same on a fixed-size string.
[PATCH] BUG/MINOR: tcpcheck: Update .health threshold of agent inside an agent-check
If an agent-check is configured for a server, When the response is parsed,
the .health threshold of the agent must be updated on up/down/stopped/fail
command and not the threshold of the health-check. Otherwise, the
agent-check will compete with the health-check and may mark a DOWN server as
UP.
This patch should fix the issue #1176. It must be backported as far as 2.2.
(cherry picked from commit 24ec9434271345857b42cc5bd9c6b497ab01a7e4) Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 789bbdc88d7ffe8f520532efb18148ea52ede4ca) Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
Gbp-Pq: Name 0001-BUG-MINOR-tcpcheck-Update-.health-threshold-of-agent.patch
As HAProxy is running chrooted by default, we rely on an additional syslog
socket created by rsyslog inside the chroot for logging. As this socket cannot
trigger syslog activation, we explicitly order HAProxy after rsyslog.service.
Note that we are not using syslog.service here, since the additional socket is
rsyslog-specific.
Forwarded: no
Last-Update: 2017-12-01
Gbp-Pq: Name haproxy.service-start-after-syslog.patch
* Non-maintainer upload by the Security Team.
* BUG/MEDIUM: mux-h2: Refuse interim responses with end-stream flag set
(CVE-2023-0056)
* BUG/CRITICAL: http: properly reject empty http header field names
(CVE-2023-25725)
projects / haproxy.git / log