clean up passing of struct passwd from monitor to preauth privsep

process. No longer copy entire struct w/ pointer addresses, but
pass remaining scalar fields explicitly,

Prompted by Yuichiro NAITO, feedback Thorsten Glaser; ok dtucker@

2 files changed, 30 insertions, 14 deletions

diff --git a/usr.bin/ssh/monitor.c b/usr.bin/ssh/monitor.c
index d71520b0d53..fd0cd4b2aea 100644
--- a/usr.bin/ssh/monitor.c
+++ b/usr.bin/ssh/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.217 2020/10/18 11:32:01 djm Exp $ */
+/* $OpenBSD: monitor.c,v 1.218 2020/11/27 00:37:10 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -639,8 +639,14 @@ mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m)
 	return (0);
 }
 
-/* Retrieves the password entry and also checks if the user is permitted */
+#define PUTPW(b, id) \
+	do { \
+		if ((r = sshbuf_put_string(b, \
+		    &pwent->id, sizeof(pwent->id))) != 0) \
+			fatal_fr(r, "assemble %s", #id); \
+	} while (0)
 
+/* Retrieves the password entry and also checks if the user is permitted */
 int
 mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m)
 {
@@ -676,10 +682,14 @@ mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m)
 	authctxt->pw = pwent;
 	authctxt->valid = 1;
 
-	/* XXX don't sent pwent to unpriv; send fake class/dir/shell too */
-	if ((r = sshbuf_put_u8(m, 1)) != 0 ||
-	    (r = sshbuf_put_string(m, pwent, sizeof(*pwent))) != 0 ||
-	    (r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 ||
+	/* XXX send fake class/dir/shell, etc. */
+	if ((r = sshbuf_put_u8(m, 1)) != 0)
+		fatal_fr(r, "assemble ok");
+	PUTPW(m, pw_uid);
+	PUTPW(m, pw_gid);
+	PUTPW(m, pw_change);
+	PUTPW(m, pw_expire);
+	if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 ||
 	    (r = sshbuf_put_cstring(m, "*")) != 0 ||
 	    (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 ||
 	    (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 ||
diff --git a/usr.bin/ssh/monitor_wrap.c b/usr.bin/ssh/monitor_wrap.c
index d4ab8620dad..890925005f1 100644
--- a/usr.bin/ssh/monitor_wrap.c
+++ b/usr.bin/ssh/monitor_wrap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.c,v 1.121 2020/10/18 11:32:01 djm Exp $ */
+/* $OpenBSD: monitor_wrap.c,v 1.122 2020/11/27 00:37:10 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -242,6 +242,15 @@ mm_sshkey_sign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
 	return (0);
 }
 
+#define GETPW(b, id) \
+	do { \
+		if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) \
+			fatal_fr(r, "parse pw %s", #id); \
+		if (len != sizeof(pw->id)) \
+			fatal_fr(r, "bad length for %s", #id); \
+		memcpy(&pw->id, p, len); \
+	} while (0)
+
 struct passwd *
 mm_getpwnamallow(struct ssh *ssh, const char *username)
 {
@@ -273,14 +282,11 @@ mm_getpwnamallow(struct ssh *ssh, const char *username)
 		goto out;
 	}
 
-	/* XXX don't like passing struct passwd like this */
 	pw = xcalloc(sizeof(*pw), 1);
-	if ((r = sshbuf_get_string_direct(m, &p, &len)) != 0)
-		fatal_fr(r, "parse");
-	if (len != sizeof(*pw))
-		fatal_f("struct passwd size mismatch");
-	memcpy(pw, p, sizeof(*pw));
-
+	GETPW(m, pw_uid);
+	GETPW(m, pw_gid);
+	GETPW(m, pw_change);
+	GETPW(m, pw_expire);
 	if ((r = sshbuf_get_cstring(m, &pw->pw_name, NULL)) != 0 ||
 	    (r = sshbuf_get_cstring(m, &pw->pw_passwd, NULL)) != 0 ||
 	    (r = sshbuf_get_cstring(m, &pw->pw_gecos, NULL)) != 0 ||