ssh: reject RekeyThresholds over MaxInt64
This fixes weirdness when users use int64(-1) as sentinel value.
Also, really use cipher specific default thresholds. These were added
in a59c127441a8ae2ad9b0fb300ab36a6558bba697, but weren't taking
effect. Add a test.
Fixes golang/go#19639
Change-Id: Ie9518a0ff12fded2fca35465abb427d7a9f84340
Reviewed-on: https://go-review.googlesource.com/39431
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/ssh/common.go b/ssh/common.go
index aa5535e..dc39e4d 100644
--- a/ssh/common.go
+++ b/ssh/common.go
@@ -9,6 +9,7 @@
"crypto/rand"
"fmt"
"io"
+ "math"
"sync"
_ "crypto/sha1"
@@ -186,7 +187,7 @@
// The maximum number of bytes sent or received after which a
// new key is negotiated. It must be at least 256. If
- // unspecified, 1 gigabyte is used.
+ // unspecified, a size suitable for the chosen cipher is used.
RekeyThreshold uint64
// The allowed key exchanges algorithms. If unspecified then a
@@ -230,11 +231,12 @@
}
if c.RekeyThreshold == 0 {
- // RFC 4253, section 9 suggests rekeying after 1G.
- c.RekeyThreshold = 1 << 30
- }
- if c.RekeyThreshold < minRekeyThreshold {
+ // cipher specific default
+ } else if c.RekeyThreshold < minRekeyThreshold {
c.RekeyThreshold = minRekeyThreshold
+ } else if c.RekeyThreshold >= math.MaxInt64 {
+ // Avoid weirdness if somebody uses -1 as a threshold.
+ c.RekeyThreshold = math.MaxInt64
}
}
diff --git a/ssh/handshake_test.go b/ssh/handshake_test.go
index 77d1aac..51a4c5a 100644
--- a/ssh/handshake_test.go
+++ b/ssh/handshake_test.go
@@ -526,3 +526,31 @@
t.Errorf("readPacket 3 succeeded")
}
}
+
+func TestHandshakeRekeyDefault(t *testing.T) {
+ clientConf := &ClientConfig{
+ Config: Config{
+ Ciphers: []string{"aes128-ctr"},
+ },
+ HostKeyCallback: InsecureIgnoreHostKey(),
+ }
+ trC, trS, err := handshakePair(clientConf, "addr", false)
+ if err != nil {
+ t.Fatalf("handshakePair: %v", err)
+ }
+ defer trC.Close()
+ defer trS.Close()
+
+ trC.writePacket([]byte{msgRequestSuccess, 0, 0})
+ trC.Close()
+
+ rgb := (1024 + trC.readBytesLeft) >> 30
+ wgb := (1024 + trC.writeBytesLeft) >> 30
+
+ if rgb != 64 {
+ t.Errorf("got rekey after %dG read, want 64G", rgb)
+ }
+ if wgb != 64 {
+ t.Errorf("got rekey after %dG write, want 64G", wgb)
+ }
+}
