Switch to MIT license

This allows libfsverity to be used by software with other common
licenses, e.g. LGPL, MIT, BSD, and Apache 2.0.  It also avoids the
incompatibility that some people perceive between OpenSSL and the GPL.

See discussion at
https://lkml.kernel.org/linux-fscrypt/20200211000037.189180-1-Jes.Sorensen@gmail.com/T/#u

Link: https://lkml.kernel.org/linux-fscrypt/20200731191156.22602-1-ebiggers@kernel.org
Acked-by: Chris Mason <clm@fb.com> # FB copyrighted material
Acked-by: Jes Sorensen <jsorensen@fb.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>

programs/cmd_enable.c

@@ -1,8 +1,12 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-License-Identifier: MIT
 /*
  * The 'fsverity enable' command
  *
  * Copyright 2018 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
  */
 
 #include "fsverity.h"

programs/cmd_measure.c

@@ -1,8 +1,12 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-License-Identifier: MIT
 /*
  * The 'fsverity measure' command
  *
  * Copyright 2018 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
  */
 
 #include "fsverity.h"

programs/cmd_sign.c

@@ -1,8 +1,12 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-License-Identifier: MIT
 /*
  * The 'fsverity sign' command
  *
  * Copyright 2018 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
  */
 
 #include "fsverity.h"

programs/fsverity.c

@@ -1,8 +1,12 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-License-Identifier: MIT
 /*
  * fs-verity userspace tool
  *
  * Copyright 2018 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
  */
 
 #include "fsverity.h"
@@ -84,16 +88,8 @@ void usage(const struct fsverity_command *cmd, FILE *fp)
 
 static void show_version(void)
 {
-	printf(
-"fsverity v%d.%d\n"
-"Copyright 2018 Google LLC\n"
-"License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>.\n"
-"This is free software: you are free to change and redistribute it.\n"
-"There is NO WARRANTY, to the extent permitted by law.\n"
-"\n"
-"Report bugs to linux-fscrypt@vger.kernel.org.\n",
-		FSVERITY_UTILS_MAJOR_VERSION,
-		FSVERITY_UTILS_MINOR_VERSION);
+	printf("fsverity v%d.%d\n", FSVERITY_UTILS_MAJOR_VERSION,
+	       FSVERITY_UTILS_MINOR_VERSION);
 }
 
 static void handle_common_options(int argc, char *argv[],

programs/fsverity.h

@@ -1,8 +1,12 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* SPDX-License-Identifier: MIT */
 /*
  * Private header for the 'fsverity' program
  *
  * Copyright 2018 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
  */
 #ifndef PROGRAMS_FSVERITY_H
 #define PROGRAMS_FSVERITY_H

programs/test_compute_digest.c

@@ -1,8 +1,12 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-License-Identifier: MIT
 /*
  * Test libfsverity_compute_digest().
  *
  * Copyright 2020 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
  */
 
 #include "utils.h"

programs/test_hash_algs.c

@@ -1,8 +1,12 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-License-Identifier: MIT
 /*
  * Test the hash algorithm-related libfsverity APIs.
  *
  * Copyright 2020 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
  */
 
 #include "utils.h"

programs/test_sign_digest.c

@@ -1,8 +1,12 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-License-Identifier: MIT
 /*
  * Test libfsverity_sign_digest().
  *
  * Copyright 2020 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
  */
 
 #include "utils.h"

programs/utils.c

@@ -1,8 +1,12 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-License-Identifier: MIT
 /*
  * Utility functions for the 'fsverity' program
  *
  * Copyright 2018 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
  */
 
 #include "utils.h"

programs/utils.h

@@ -1,8 +1,12 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* SPDX-License-Identifier: MIT */
 /*
  * Utility functions for programs
  *
  * Copyright 2018 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
  */
 #ifndef PROGRAMS_UTILS_H
 #define PROGRAMS_UTILS_H