Hi,
while looking into Cygwin's tty code, I stumbled over this problem:
Every time you log in to Cygwin via sshd, the pty's permissions are
set like this:
$ ls -l `tty`
crw--w--w- 1 user group 136, 2 Aug 27 13:06 /dev/pty2
Since Cygwin sets the permissions more tight to begin with, I was
wondering why the permissions are this open. Turns out, sshd sets
them like this:
/* 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;
}
On Windows no group called "tty" exists, so sshd always sets the
permissions to 0622 on Cygwin.
My question is, isn't that a security problem? Shouldn't the
permissions set to 0600 if a "tty" group doesn't exist, otherwise
everyone can write to the user's tty? What am I missing?
Thanks,
Corinna
--
Corinna Vinschen
Cygwin Maintainer
Red Hat
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