[go] net/http: validate Host header before sending

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Damien Neil (Gerrit)

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Jun 29, 2023, 1:00:12 PM6/29/23
to goph...@pubsubhelper.golang.org, golang-...@googlegroups.com, Tatiana Bradley, Gopher Robot, golang-co...@googlegroups.com

Damien Neil submitted this change.

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Approvals: Tatiana Bradley: Looks good to me, approved Gopher Robot: TryBots succeeded Damien Neil: Run TryBots
net/http: validate Host header before sending

Verify that the Host header we send is valid.
Avoids surprising behavior such as a Host of "go.dev\r\nX-Evil:oops"
adding an X-Evil header to HTTP/1 requests.

Add a test, skip the test for HTTP/2. HTTP/2 is not vulnerable to
header injection in the way HTTP/1 is, but x/net/http2 doesn't validate
the header and will go into a retry loop when the server rejects it.
CL 506995 adds the necessary validation to x/net/http2.

For #60374

Change-Id: I05cb6866a9bead043101954dfded199258c6dd04
Reviewed-on: https://go-review.googlesource.com/c/go/+/506996
Reviewed-by: Tatiana Bradley <tatiana...@google.com>
TryBot-Result: Gopher Robot <go...@golang.org>
Run-TryBot: Damien Neil <dn...@google.com>
---
M src/net/http/http_test.go
M src/net/http/request.go
M src/net/http/request_test.go
M src/net/http/transport_test.go
4 files changed, 31 insertions(+), 75 deletions(-)

diff --git a/src/net/http/http_test.go b/src/net/http/http_test.go
index 1c9fb33..91bb1b2 100644
--- a/src/net/http/http_test.go
+++ b/src/net/http/http_test.go
@@ -48,35 +48,6 @@
}
}

-func TestCleanHost(t *testing.T) {
- tests := []struct {
- in, want string
- }{
- {"www.google.com", "www.google.com"},
- {"www.google.com foo", "www.google.com"},
- {"www.google.com/foo", "www.google.com"},
- {" first character is a space", ""},
- {"[1::6]:8080", "[1::6]:8080"},
-
- // Punycode:
- {"гофер.рф/foo", "xn--c1ae0ajs.xn--p1ai"},
- {"bücher.de", "xn--bcher-kva.de"},
- {"bücher.de:8080", "xn--bcher-kva.de:8080"},
- // Verify we convert to lowercase before punycode:
- {"BÜCHER.de", "xn--bcher-kva.de"},
- {"BÜCHER.de:8080", "xn--bcher-kva.de:8080"},
- // Verify we normalize to NFC before punycode:
- {"gophér.nfc", "xn--gophr-esa.nfc"}, // NFC input; no work needed
- {"goph\u0065\u0301r.nfd", "xn--gophr-esa.nfd"}, // NFD input
- }
- for _, tt := range tests {
- got := cleanHost(tt.in)
- if tt.want != got {
- t.Errorf("cleanHost(%q) = %q, want %q", tt.in, got, tt.want)
- }
- }
-}
-
// Test that cmd/go doesn't link in the HTTP server.
//
// This catches accidental dependencies between the HTTP transport and
diff --git a/src/net/http/request.go b/src/net/http/request.go
index 4e91904..bd86837 100644
--- a/src/net/http/request.go
+++ b/src/net/http/request.go
@@ -17,7 +17,6 @@
"io"
"mime"
"mime/multipart"
- "net"
"net/http/httptrace"
"net/http/internal/ascii"
"net/textproto"
@@ -27,6 +26,7 @@
"strings"
"sync"

+ "golang.org/x/net/http/httpguts"
"golang.org/x/net/idna"
)

@@ -580,12 +580,19 @@
// is not given, use the host from the request URL.
//
// Clean the host, in case it arrives with unexpected stuff in it.
- host := cleanHost(r.Host)
+ host := r.Host
if host == "" {
if r.URL == nil {
return errMissingHost
}
- host = cleanHost(r.URL.Host)
+ host = r.URL.Host
+ }
+ host, err = httpguts.PunycodeHostPort(host)
+ if err != nil {
+ return err
+ }
+ if !httpguts.ValidHostHeader(host) {
+ return errors.New("http: invalid Host header")
}

// According to RFC 6874, an HTTP client, proxy, or other
@@ -742,40 +749,6 @@
return idna.Lookup.ToASCII(v)
}

-// cleanHost cleans up the host sent in request's Host header.
-//
-// It both strips anything after '/' or ' ', and puts the value
-// into Punycode form, if necessary.
-//
-// Ideally we'd clean the Host header according to the spec:
-//
-// https://tools.ietf.org/html/rfc7230#section-5.4 (Host = uri-host [ ":" port ]")
-// https://tools.ietf.org/html/rfc7230#section-2.7 (uri-host -> rfc3986's host)
-// https://tools.ietf.org/html/rfc3986#section-3.2.2 (definition of host)
-//
-// But practically, what we are trying to avoid is the situation in
-// issue 11206, where a malformed Host header used in the proxy context
-// would create a bad request. So it is enough to just truncate at the
-// first offending character.
-func cleanHost(in string) string {
- if i := strings.IndexAny(in, " /"); i != -1 {
- in = in[:i]
- }
- host, port, err := net.SplitHostPort(in)
- if err != nil { // input was just a host
- a, err := idnaASCII(in)
- if err != nil {
- return in // garbage in, garbage out
- }
- return a
- }
- a, err := idnaASCII(host)
- if err != nil {
- return in // garbage in, garbage out
- }
- return net.JoinHostPort(a, port)
-}
-
// removeZone removes IPv6 zone identifier from host.
// E.g., "[fe80::1%en0]:8080" to "[fe80::1]:8080"
func removeZone(host string) string {
diff --git a/src/net/http/request_test.go b/src/net/http/request_test.go
index 78b968f..0892bc2 100644
--- a/src/net/http/request_test.go
+++ b/src/net/http/request_test.go
@@ -775,15 +775,8 @@
}
req.Host = "foo.com with spaces"
req.URL.Host = "foo.com with spaces"
- req.Write(logWrites{t, &got})
- want := []string{
- "GET /after HTTP/1.1\r\n",
- "Host: foo.com\r\n",
- "User-Agent: " + DefaultUserAgent + "\r\n",
- "\r\n",
- }
- if !reflect.DeepEqual(got, want) {
- t.Errorf("Writes = %q\n Want = %q", got, want)
+ if err := req.Write(logWrites{t, &got}); err == nil {
+ t.Errorf("Writing request with invalid Host: succeded, want error")
}
}

diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index 172aba6..028fecc 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -6731,3 +6731,22 @@
}
wg.Wait()
}
+
+func TestRequestSanitization(t *testing.T) { run(t, testRequestSanitization) }
+func testRequestSanitization(t *testing.T, mode testMode) {
+ if mode == http2Mode {
+ // Remove this after updating x/net.
+ t.Skip("https://go.dev/issue/60374 test fails when run with HTTP/2")
+ }
+ ts := newClientServerTest(t, mode, HandlerFunc(func(rw ResponseWriter, req *Request) {
+ if h, ok := req.Header["X-Evil"]; ok {
+ t.Errorf("request has X-Evil header: %q", h)
+ }
+ })).ts
+ req, _ := NewRequest("GET", ts.URL, nil)
+ req.Host = "go.dev\r\nX-Evil:evil"
+ resp, _ := ts.Client().Do(req)
+ if resp != nil {
+ resp.Body.Close()
+ }
+}

To view, visit change 506996. To unsubscribe, or for help writing mail filters, visit settings.

Gerrit-MessageType: merged
Gerrit-Project: go
Gerrit-Branch: master
Gerrit-Change-Id: I05cb6866a9bead043101954dfded199258c6dd04
Gerrit-Change-Number: 506996
Gerrit-PatchSet: 3
Gerrit-Owner: Damien Neil <dn...@google.com>
Gerrit-Reviewer: Damien Neil <dn...@google.com>
Gerrit-Reviewer: Gopher Robot <go...@golang.org>
Gerrit-Reviewer: Tatiana Bradley <tatiana...@google.com>

Joedian Reid (Gerrit)

unread,
Jul 6, 2023, 3:41:24 PM7/6/23
to Damien Neil, Tatiana Bradley, goph...@pubsubhelper.golang.org, golang-...@googlegroups.com, Dmitri Shuralyov, Roland Shoemaker, Gopher Robot, golang-co...@googlegroups.com

Joedian Reid submitted this change.

View Change

Approvals: Tatiana Bradley: Run TryBots Gopher Robot: TryBots succeeded Damien Neil: Looks good to me, approved Roland Shoemaker: Looks good to me, approved
[release-branch.go1.20] net/http: validate Host header before sending


Verify that the Host header we send is valid.
Avoids surprising behavior such as a Host of "go.dev\r\nX-Evil:oops"
adding an X-Evil header to HTTP/1 requests.

Add a test, skip the test for HTTP/2. HTTP/2 is not vulnerable to
header injection in the way HTTP/1 is, but x/net/http2 doesn't validate
the header and will go into a retry loop when the server rejects it.
CL 506995 adds the necessary validation to x/net/http2.

For #60374
Fixes #61076
For CVE-2023-29406


Change-Id: I05cb6866a9bead043101954dfded199258c6dd04
Reviewed-on: https://go-review.googlesource.com/c/go/+/506996
Reviewed-by: Tatiana Bradley <tatiana...@google.com>
TryBot-Result: Gopher Robot <go...@golang.org>
Run-TryBot: Damien Neil <dn...@google.com>
(cherry picked from commit 499458f7ca04087958987a33c2703c3ef03e27e2)
Reviewed-on: https://go-review.googlesource.com/c/go/+/507357
Reviewed-by: Damien Neil <dn...@google.com>
Run-TryBot: Tatiana Bradley <tatiana...@google.com>
Reviewed-by: Roland Shoemaker <rol...@golang.org>

---
M src/net/http/http_test.go
M src/net/http/request.go
M src/net/http/request_test.go
M src/net/http/transport_test.go
4 files changed, 31 insertions(+), 75 deletions(-)


diff --git a/src/net/http/http_test.go b/src/net/http/http_test.go
index 0d92fe5..f03272a 100644
index a45c9e3..9c888b3 100644

--- a/src/net/http/request.go
+++ b/src/net/http/request.go
@@ -17,7 +17,6 @@
"io"
"mime"
"mime/multipart"
- "net"
"net/http/httptrace"
"net/http/internal/ascii"
"net/textproto"
@@ -27,6 +26,7 @@
"strings"
"sync"

+ "golang.org/x/net/http/httpguts"
"golang.org/x/net/idna"
)

@@ -575,12 +575,19 @@

// is not given, use the host from the request URL.
//
// Clean the host, in case it arrives with unexpected stuff in it.
- host := cleanHost(r.Host)
+ host := r.Host
if host == "" {
if r.URL == nil {
return errMissingHost
}
- host = cleanHost(r.URL.Host)
+ host = r.URL.Host
+ }
+ host, err = httpguts.PunycodeHostPort(host)
+ if err != nil {
+ return err
+ }
+ if !httpguts.ValidHostHeader(host) {
+ return errors.New("http: invalid Host header")
}

// According to RFC 6874, an HTTP client, proxy, or other
@@ -737,40 +744,6 @@
index 23e49d6..86c68e4 100644
--- a/src/net/http/request_test.go
+++ b/src/net/http/request_test.go
@@ -774,15 +774,8 @@

}
req.Host = "foo.com with spaces"
req.URL.Host = "foo.com with spaces"
- req.Write(logWrites{t, &got})
- want := []string{
- "GET /after HTTP/1.1\r\n",
- "Host: foo.com\r\n",
- "User-Agent: " + DefaultUserAgent + "\r\n",
- "\r\n",
- }
- if !reflect.DeepEqual(got, want) {
- t.Errorf("Writes = %q\n Want = %q", got, want)
+ if err := req.Write(logWrites{t, &got}); err == nil {
+ t.Errorf("Writing request with invalid Host: succeded, want error")
}
}

diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index 245f73b..f4896c5 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -6654,3 +6654,22 @@

}
wg.Wait()
}
+
+func TestRequestSanitization(t *testing.T) { run(t, testRequestSanitization) }
+func testRequestSanitization(t *testing.T, mode testMode) {
+ if mode == http2Mode {
+ // Remove this after updating x/net.
+ t.Skip("https://go.dev/issue/60374 test fails when run with HTTP/2")
+ }
+ ts := newClientServerTest(t, mode, HandlerFunc(func(rw ResponseWriter, req *Request) {
+ if h, ok := req.Header["X-Evil"]; ok {
+ t.Errorf("request has X-Evil header: %q", h)
+ }
+ })).ts
+ req, _ := NewRequest("GET", ts.URL, nil)
+ req.Host = "go.dev\r\nX-Evil:evil"
+ resp, _ := ts.Client().Do(req)
+ if resp != nil {
+ resp.Body.Close()
+ }
+}

To view, visit change 507357. To unsubscribe, or for help writing mail filters, visit settings.

Gerrit-MessageType: merged
Gerrit-Project: go
Gerrit-Branch: release-branch.go1.20
Gerrit-Change-Id: I05cb6866a9bead043101954dfded199258c6dd04
Gerrit-Change-Number: 507357
Gerrit-PatchSet: 6
Gerrit-Owner: Tatiana Bradley <tatiana...@google.com>
Gerrit-Reviewer: Damien Neil <dn...@google.com>
Gerrit-Reviewer: Gopher Robot <go...@golang.org>
Gerrit-Reviewer: Joedian Reid <joe...@golang.org>
Gerrit-Reviewer: Roland Shoemaker <rol...@golang.org>
Gerrit-Reviewer: Tatiana Bradley <tatiana...@google.com>
Gerrit-CC: Dmitri Shuralyov <dmit...@golang.org>

Joedian Reid (Gerrit)

unread,
Jul 6, 2023, 3:41:25 PM7/6/23
to Damien Neil, Tatiana Bradley, goph...@pubsubhelper.golang.org, golang-...@googlegroups.com, Gopher Robot, Roland Shoemaker, golang-co...@googlegroups.com

Joedian Reid submitted this change.

View Change

Approvals: Tatiana Bradley: Looks good to me, approved; Run TryBots Gopher Robot: TryBots succeeded Roland Shoemaker: Looks good to me, approved
[release-branch.go1.19] net/http: validate Host header before sending


Verify that the Host header we send is valid.
Avoids surprising behavior such as a Host of "go.dev\r\nX-Evil:oops"
adding an X-Evil header to HTTP/1 requests.

Add a test, skip the test for HTTP/2. HTTP/2 is not vulnerable to
header injection in the way HTTP/1 is, but x/net/http2 doesn't validate
the header and will go into a retry loop when the server rejects it.
CL 506995 adds the necessary validation to x/net/http2.

Updates #60374
Fixes #61075

For CVE-2023-29406

Change-Id: I05cb6866a9bead043101954dfded199258c6dd04
Reviewed-on: https://go-review.googlesource.com/c/go/+/506996
Reviewed-by: Tatiana Bradley <tatiana...@google.com>
TryBot-Result: Gopher Robot <go...@golang.org>
Run-TryBot: Damien Neil <dn...@google.com>
(cherry picked from commit 499458f7ca04087958987a33c2703c3ef03e27e2)

Run-TryBot: Tatiana Bradley <tatiana...@google.com>
Reviewed-by: Roland Shoemaker <rol...@golang.org>
---
M src/net/http/http_test.go
M src/net/http/request.go
M src/net/http/request_test.go
M src/net/http/transport_test.go
4 files changed, 30 insertions(+), 75 deletions(-)

index cead91d..3100037 100644

--- a/src/net/http/request.go
+++ b/src/net/http/request.go
@@ -17,7 +17,6 @@
"io"
"mime"
"mime/multipart"
- "net"
"net/http/httptrace"
"net/http/internal/ascii"
"net/textproto"
@@ -27,6 +26,7 @@
"strings"
"sync"

+ "golang.org/x/net/http/httpguts"
"golang.org/x/net/idna"
)

@@ -571,12 +571,19 @@

// is not given, use the host from the request URL.
//
// Clean the host, in case it arrives with unexpected stuff in it.
- host := cleanHost(r.Host)
+ host := r.Host
if host == "" {
if r.URL == nil {
return errMissingHost
}
- host = cleanHost(r.URL.Host)
+ host = r.URL.Host
+ }
+ host, err = httpguts.PunycodeHostPort(host)
+ if err != nil {
+ return err
+ }
+ if !httpguts.ValidHostHeader(host) {
+ return errors.New("http: invalid Host header")
}

// According to RFC 6874, an HTTP client, proxy, or other
@@ -733,40 +740,6 @@
index 0ec8f24..fddc85d 100644
--- a/src/net/http/request_test.go
+++ b/src/net/http/request_test.go
@@ -778,15 +778,8 @@

}
req.Host = "foo.com with spaces"
req.URL.Host = "foo.com with spaces"
- req.Write(logWrites{t, &got})
- want := []string{
- "GET /after HTTP/1.1\r\n",
- "Host: foo.com\r\n",
- "User-Agent: " + DefaultUserAgent + "\r\n",
- "\r\n",
- }
- if !reflect.DeepEqual(got, want) {
- t.Errorf("Writes = %q\n Want = %q", got, want)
+ if err := req.Write(logWrites{t, &got}); err == nil {
+ t.Errorf("Writing request with invalid Host: succeded, want error")
}
}

diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index cba35db..985d062 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -6566,3 +6566,21 @@

}
wg.Wait()
}
+
+func TestRequestSanitization(t *testing.T) {
+	setParallel(t)
+ defer afterTest(t)
+
+ ts := newClientServerTest(t, h1Mode, HandlerFunc(func(rw ResponseWriter, req *Request) {

+ if h, ok := req.Header["X-Evil"]; ok {
+ t.Errorf("request has X-Evil header: %q", h)
+ }
+ })).ts
+	defer ts.Close()

+ req, _ := NewRequest("GET", ts.URL, nil)
+ req.Host = "go.dev\r\nX-Evil:evil"
+ resp, _ := ts.Client().Do(req)
+ if resp != nil {
+ resp.Body.Close()
+ }
+}

To view, visit change 507358. To unsubscribe, or for help writing mail filters, visit settings.

Gerrit-MessageType: merged
Gerrit-Project: go
Gerrit-Branch: release-branch.go1.19
Gerrit-Change-Id: I05cb6866a9bead043101954dfded199258c6dd04
Gerrit-Change-Number: 507358
Gerrit-PatchSet: 15
Gerrit-Owner: Tatiana Bradley <tatiana...@google.com>
Gerrit-Reviewer: Gopher Robot <go...@golang.org>
Gerrit-Reviewer: Joedian Reid <joe...@golang.org>
Gerrit-Reviewer: Roland Shoemaker <rol...@golang.org>
Gerrit-Reviewer: Tatiana Bradley <tatiana...@google.com>
Gerrit-CC: Damien Neil <dn...@google.com>
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