ssh: ignore invalid MACs and KEXs just like we do for ciphers

Tighter validation could cause backwards incompatibility issues, eg configurations with valid and invalid MACs, KEXs, ciphers currently work if a supported algorithm is negotiated and that's also the scenario of removing support for an existing algorithm. Fixes golang/go#39397 Change-Id: If90253ba89e1d8f732cc1e1c3d24fe0a1e2dac71 Reviewed-on: https://go-review.googlesource.com/c/crypto/+/512175 Run-TryBot: Han-Wen Nienhuys <hanwen@google.com> Reviewed-by: Filippo Valsorda <filippo@golang.org> Reviewed-by: Han-Wen Nienhuys <hanwen@google.com> Auto-Submit: Filippo Valsorda <filippo@golang.org> Reviewed-by: David Chase <drchase@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
2023-07-31 15:35:32 +00:00
parent d08e19beac
commit ddfa82138e
2 changed files with 113 additions and 7 deletions
@@ -254,3 +254,93 @@ func TestNewClientConn(t *testing.T) {
 		})
 	}
 }
+
+func TestUnsupportedAlgorithm(t *testing.T) {
+	for _, tt := range []struct {
+		name      string
+		config    Config
+		wantError string
+	}{
+		{
+			"unsupported KEX",
+			Config{
+				KeyExchanges: []string{"unsupported"},
+			},
+			"no common algorithm",
+		},
+		{
+			"unsupported and supported KEXs",
+			Config{
+				KeyExchanges: []string{"unsupported", kexAlgoCurve25519SHA256},
+			},
+			"",
+		},
+		{
+			"unsupported cipher",
+			Config{
+				Ciphers: []string{"unsupported"},
+			},
+			"no common algorithm",
+		},
+		{
+			"unsupported and supported ciphers",
+			Config{
+				Ciphers: []string{"unsupported", chacha20Poly1305ID},
+			},
+			"",
+		},
+		{
+			"unsupported MAC",
+			Config{
+				MACs: []string{"unsupported"},
+				// MAC is used for non AAED ciphers.
+				Ciphers: []string{"aes256-ctr"},
+			},
+			"no common algorithm",
+		},
+		{
+			"unsupported and supported MACs",
+			Config{
+				MACs: []string{"unsupported", "hmac-sha2-256-etm@openssh.com"},
+				// MAC is used for non AAED ciphers.
+				Ciphers: []string{"aes256-ctr"},
+			},
+			"",
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			c1, c2, err := netPipe()
+			if err != nil {
+				t.Fatalf("netPipe: %v", err)
+			}
+			defer c1.Close()
+			defer c2.Close()
+
+			serverConf := &ServerConfig{
+				Config: tt.config,
+				PasswordCallback: func(conn ConnMetadata, password []byte) (*Permissions, error) {
+					return &Permissions{}, nil
+				},
+			}
+			serverConf.AddHostKey(testSigners["rsa"])
+			go NewServerConn(c1, serverConf)
+
+			clientConf := &ClientConfig{
+				User:   "testuser",
+				Config: tt.config,
+				Auth: []AuthMethod{
+					Password("testpw"),
+				},
+				HostKeyCallback: InsecureIgnoreHostKey(),
+			}
+			_, _, _, err = NewClientConn(c2, "", clientConf)
+			if err != nil {
+				if tt.wantError == "" || !strings.Contains(err.Error(), tt.wantError) {
+					t.Errorf("%s: got error %q, missing %q", tt.name, err.Error(), tt.wantError)
+				}
+			} else if tt.wantError != "" {
+				t.Errorf("%s: succeeded, but want error string %q", tt.name, tt.wantError)
+			}
+		})
+	}
+}