81 lines
3.0 KiB
Diff
81 lines
3.0 KiB
Diff
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From f8b2315b75ad8a9c8b386502504525e1816982cd Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Dan=20=C4=8Cerm=C3=A1k?= <dcermak@suse.com>
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Date: Wed, 12 Feb 2025 15:33:28 +0100
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Subject: [PATCH 4/4] http2: close connections when receiving too many headers
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(#1)
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Maintaining HPACK state requires that we parse and process
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all HEADERS and CONTINUATION frames on a connection.
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When a request's headers exceed MaxHeaderBytes, we don't
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allocate memory to store the excess headers but we do
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parse them. This permits an attacker to cause an HTTP/2
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endpoint to read arbitrary amounts of data, all associated
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with a request which is going to be rejected.
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Set a limit on the amount of excess header frames we
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will process before closing a connection.
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Thanks to Bartek Nowotarski for reporting this issue.
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Fixes CVE-2023-45288
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Fixes bsc#1236531
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This is a backport of
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https://go.googlesource.com/net/+/ba872109ef2dc8f1da778651bd1fd3792d0e4587%5E%21/#F0
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---
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vendor/golang.org/x/net/http2/frame.go | 31 ++++++++++++++++++++++++++
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1 file changed, 31 insertions(+)
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diff --git a/vendor/golang.org/x/net/http2/frame.go b/vendor/golang.org/x/net/http2/frame.go
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index e2b298d85..a5a94411d 100644
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--- a/vendor/golang.org/x/net/http2/frame.go
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+++ b/vendor/golang.org/x/net/http2/frame.go
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@@ -1564,6 +1564,7 @@ func (fr *Framer) readMetaFrame(hf *HeadersFrame) (*MetaHeadersFrame, error) {
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if size > remainSize {
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hdec.SetEmitEnabled(false)
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mh.Truncated = true
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+ remainSize = 0
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return
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}
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remainSize -= size
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@@ -1576,6 +1577,36 @@ func (fr *Framer) readMetaFrame(hf *HeadersFrame) (*MetaHeadersFrame, error) {
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var hc headersOrContinuation = hf
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for {
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frag := hc.HeaderBlockFragment()
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+
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+ // Avoid parsing large amounts of headers that we will then discard.
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+ // If the sender exceeds the max header list size by too much,
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+ // skip parsing the fragment and close the connection.
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+ //
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+ // "Too much" is either any CONTINUATION frame after we've already
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+ // exceeded the max header list size (in which case remainSize is 0),
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+ // or a frame whose encoded size is more than twice the remaining
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+ // header list bytes we're willing to accept.
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+ if int64(len(frag)) > int64(2*remainSize) {
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+ if VerboseLogs {
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+ log.Printf("http2: header list too large")
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+ }
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+ // It would be nice to send a RST_STREAM before sending the GOAWAY,
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+ // but the struture of the server's frame writer makes this difficult.
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+ return nil, ConnectionError(ErrCodeProtocol)
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+ }
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+
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+ // Also close the connection after any CONTINUATION frame following an
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+ // invalid header, since we stop tracking the size of the headers after
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+ // an invalid one.
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+ if invalid != nil {
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+ if VerboseLogs {
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+ log.Printf("http2: invalid header: %v", invalid)
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+ }
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+ // It would be nice to send a RST_STREAM before sending the GOAWAY,
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+ // but the struture of the server's frame writer makes this difficult.
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+ return nil, ConnectionError(ErrCodeProtocol)
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+ }
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+
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if _, err := hdec.Write(frag); err != nil {
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return nil, ConnectionError(ErrCodeCompression)
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}
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--
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2.48.1
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