auth: read only the first password-file line (#1137)

* auth: read only the first password-file line

strtok() skips leading delimiters, so an empty first line followed by a
password was interpreted as that password. Stop at the first CR/LF
instead, keeping an empty first line empty and making file and stdin
behavior consistent.

Add daemon-auth regression coverage for LF, CRLF, empty input, an empty
first line, and a final line without a newline for both input sources.

Fixes #1134.

Signed-off-by: Eduard Zateev <hackerowskiy@gmail.com>

* tests: reject password-file fallback for empty first lines

Supply the valid daemon password through RSYNC_PASSWORD in negative
cases, then require exit status 1 and the password read diagnostic.

Signed-off-by: Eduard Zateev <hackerowskiy@gmail.com>

---------

Signed-off-by: Eduard Zateev <hackerowskiy@gmail.com>

authenticate.c

@@ -271,8 +271,10 @@ static const char *getpassf(const char *filename)
 
 	if (n > 0) {
 		buffer[n] = '\0';
-		if ((p = strtok(buffer, "\n\r")) != NULL)
-			return strdup(p);
+		p = buffer + strcspn(buffer, "\n\r");
+		*p = '\0';
+		if (buffer[0] != '\0')
+			return strdup(buffer);
 	}
 
 	rprintf(FERROR, "ERROR: failed to read a password from %s\n", filename);

testsuite/password-file-first-line_test.py

@@ -0,0 +1,70 @@
+#!/usr/bin/env python3
+"""Only the first line of --password-file is used, for files and stdin."""
+
+import os
+import subprocess
+
+from rsyncfns import (
+    SCRATCHDIR, makepath, rmtree, rsync_argv, start_test_daemon,
+    test_fail, write_daemon_conf,
+)
+
+DAEMON_PORT = 12904
+USER = 'tuser'
+PASSWORD = b'secretpass'
+
+base = SCRATCHDIR / 'password-file-first-line'
+rmtree(base)
+src = base / 'src'
+dest = base / 'dest'
+makepath(src)
+(src / 'payload').write_text('regression test\n')
+secrets = base / 'secrets'
+secrets.write_bytes(USER.encode() + b':' + PASSWORD + b'\n')
+secrets.chmod(0o600)
+conf = write_daemon_conf([
+    ('auth', {'path': dest, 'read only': 'no',
+              'auth users': USER, 'secrets file': secrets}),
+])
+url = start_test_daemon(conf, DAEMON_PORT)
+userurl = url.replace('rsync://', f'rsync://{USER}@', 1)
+
+cases = (
+    ('LF', PASSWORD + b'\nignored\n', True),
+    ('CRLF', PASSWORD + b'\r\nignored\r\n', True),
+    ('empty-file', b'', False),
+    ('empty-first-line', b'\n' + PASSWORD + b'\n', False),
+    ('no-final-newline', PASSWORD, True),
+)
+
+for source in ('file', 'stdin'):
+    for name, contents, succeeds in cases:
+        rmtree(dest)
+        makepath(dest)
+        args = ['-a', f'{src}/', f'{userurl}auth/']
+        if source == 'file':
+            pwfile = base / f'{name}.password'
+            pwfile.write_bytes(contents)
+            pwfile.chmod(0o600)
+            args.insert(1, f'--password-file={pwfile}')
+            stdin = subprocess.DEVNULL
+        else:
+            args.insert(1, '--password-file=-')
+            stdin = subprocess.PIPE
+        proc = subprocess.run(rsync_argv(*args), input=contents if source == 'stdin' else None,
+                              stdin=stdin if source == 'file' else None,
+                              stdout=subprocess.DEVNULL, stderr=subprocess.PIPE,
+                              text=False, timeout=20,
+                              env={**os.environ, 'RSYNC_PASSWORD':
+                                   'wrong-fallback' if succeeds else PASSWORD.decode()})
+        passed = proc.returncode == 0
+        if passed != succeeds:
+            test_fail(f'{source}/{name}: expected success={succeeds}, '
+                      f'rc={proc.returncode}, stderr={proc.stderr!r}')
+
+        if not succeeds and (proc.returncode != 1
+                             or b'failed to read a password' not in proc.stderr):
+            test_fail(f'{source}/{name}: expected password read failure, '
+                      f'rc={proc.returncode}, stderr={proc.stderr!r}')
+
+print('password-file: first-line behavior matches for files and stdin')