From 8c9cbbb142cfbe595ead3d0003638e079053e683 Mon Sep 17 00:00:00 2001
From: Ori Bernstein <ori@eigenstate.org>
Date: Sun, 17 Jan 2021 18:01:53 -0800
Subject: [PATCH] passwd: make legacy mode explicit

Passwd used to produce a very confusing error
about DES not being enabled whenever the password
was mistyped. This happened because we attempted
to guess what authentication method to use, and
preseneted the error from the wrong one on failure.

This puts the legacy mode behind a flag, so that
we don't even try the old method unless it's
explicitly requested.
---
 sys/man/1/passwd          | 13 +++++++++++++
 sys/src/cmd/auth/passwd.c | 33 +++++++++++++--------------------
 2 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/sys/man/1/passwd b/sys/man/1/passwd
index 70d60532f..28343c054 100644
--- a/sys/man/1/passwd
+++ b/sys/man/1/passwd
@@ -4,6 +4,9 @@ passwd, netkey \- change or verify user password
 .SH SYNOPSIS
 .B passwd
 [
+.IR -1
+]
+[
 .IR username [@ domain ]
 ]
 .PP
@@ -27,6 +30,16 @@ secret.
 New passwords and secrets must be typed twice, to forestall mistakes.
 New passwords must be sufficiently hard to guess.
 They may be of any length greater than seven characters.
+.PP
+By default, passwd requires the auth server to support
+.IR dp9ik (6).
+The
+.I -1
+flag forces
+.B passwd
+to authenticate using
+.IR p9sk1 (6).
+
 .PP
 .I Netkey
 prompts for a password to encrypt network challenges.
diff --git a/sys/src/cmd/auth/passwd.c b/sys/src/cmd/auth/passwd.c
index db551d67c..eb14ddca8 100644
--- a/sys/src/cmd/auth/passwd.c
+++ b/sys/src/cmd/auth/passwd.c
@@ -7,7 +7,7 @@
 void
 main(int argc, char **argv)
 {
-	int fd, n, try;
+	int fd, n, dp9ik;
 	Ticketreq tr;
 	Ticket t;
 	Passwordreq pr;
@@ -15,7 +15,14 @@ main(int argc, char **argv)
 	char buf[512];
 	char *s, *user;
 
+	dp9ik = 1;
 	ARGBEGIN{
+	case '1':
+		dp9ik = 0;
+		break;
+	default:
+		fprint(2, "%s [-1]\n", argv0);
+		exits("usage");
 	}ARGEND
 
 	argv0 = "passwd";
@@ -48,31 +55,17 @@ main(int argc, char **argv)
 	memset(&pr, 0, sizeof(pr));
 	getpass(&key, pr.old, 0, 0);
 
-	/*
-	 *  negotiate PAK key. we need to retry in case the AS does
-	 *  not support the AuthPAK request or when the user has
-	 *  not yet setup a new key and the AS made one up.
-	 */
-	try = 0;
-	authpak_hash(&key, tr.uid);
-	if(_asgetpakkey(fd, &tr, &key) < 0){
-Retry:
-		try++;
-		close(fd);
-		fd = authdial(nil, s);
-		if(fd < 0)
-			error("authdial: %r");
+	if(dp9ik){
+		authpak_hash(&key, tr.uid);
+		if(_asgetpakkey(fd, &tr, &key) < 0)
+			error("%r");
 	}
-	/* send ticket request to AS */
 	if(_asrequest(fd, &tr) < 0)
 		error("%r");
 	if(_asgetresp(fd, &t, nil, &key) < 0)
 		error("%r");
-	if(t.num != AuthTp || strcmp(t.cuid, tr.uid) != 0){
-		if(try == 0)
-			goto Retry;
+	if(t.num != AuthTp || strcmp(t.cuid, tr.uid) != 0)
 		error("bad password");
-	}
 
 	/* loop trying new passwords */
 	for(;;){