CVE-2015-6565 openssh: Incorrectly set TTYs to be world-writable

fix pty permissions; patch from Nikolay Edigaryev; ok deraadt

Upstream-Status: Backport

merged two changes into one.
[1] https://anongit.mindrot.org/openssh.git/commit/sshpty.c?id=a5883d4eccb94b16c355987f58f86a7dee17a0c2
tighten permissions on pty when the "tty" group does not exist; pointed out by Corinna Vinschen; ok markus

[2] https://anongit.mindrot.org/openssh.git/commit/sshpty.c?id=6f941396b6835ad18018845f515b0c4fe20be21a
fix pty permissions; patch from Nikolay Edigaryev; ok deraadt

Signed-off-by: Armin Kuster <akuster@mvista.com>

Index: openssh-6.7p1/sshpty.c
===================================================================
--- openssh-6.7p1.orig/sshpty.c
+++ openssh-6.7p1/sshpty.c
@@ -196,13 +196,8 @@ pty_setowner(struct passwd *pw, const ch
 
 	/* Determine the group to make the owner of the tty. */
 	grp = getgrnam("tty");
-	if (grp) {
-		gid = grp->gr_gid;
-		mode = S_IRUSR | S_IWUSR | S_IWGRP;
-	} else {
-		gid = pw->pw_gid;
-		mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
-	}
+    gid = (grp != NULL) ? grp->gr_gid : pw->pw_gid;
+    mode = (grp != NULL) ? 0620 : 0600;
 
 	/*
 	 * Change owner and mode of the tty as required.