This fixes a race condition in ptrace-based intercept mode when
running the command in a pty. It was possible for the monitor to
receive SIGCHLD when the command sent itself SIGSTOP before the
main sudo process did.
This makes it possible to determine whether we really need to execute
the command via the sesh helper. What was left of selinux_setup()
is now selinux_relabel_tty() and selinux_audit_role_change().
This allows intercept mode to work with shells that close all open
fds upon startup. The ctor in sudo_intercept.so requests the port
number and secret over the socket inherited from the parent then
closes it. For each policy request, a TCP connection is made to
the sudo parent process to perform the policy check. Child processes
re-use the TCP socket to request the port number and secret just like
the initial process started by sudo does.
The goal is to make it harder for someone to have a fake policy checker.
This will not stop a determined adversary since the secret is present
in the address space of the running process.
Previously we needed to include headers required by the various
sudo*h files. Now those files are more self-sufficient and we
should only include headers needed by code in the various .c files.
We can't use run_command() to run sesh, that will use the sudo event
loop (and might run it in a pty!).
There's no need to relabel the tty when copying files.
Get the path to sesh from sudo.conf.
Currently, for SELinux RBAC, the editor runs with the target user's
security context. This defeats the purpose of sudoedit. Fixing
that requires passing file descriptors between the main sudo process
(running with the invoking user's security context) and sesh (runnning
with the target user's security context).
1) don't assume snprintf() returns -1 on error, check for <0
2) when comparing return value of sizeof(foo), cast the sizeof, not the len
3) cast return value to void in cases where snprintf cannot fail
to handle EINTR. We now use SA_RESTART with signals so this is not
needed and is potentially dangerous if it is possible to receive
SIGTTIN or SIGTTOU (which it currently is not).
non-pty code paths into their own event loops. The non-pty exec
code is now contained in exec_nopty.c and the pty exec code is split
between exec_pty.c (parent process) and exec_monitor.c (session leader).
This results in a small bit of duplicated code but improves readability.
Some of the duplicated code will fall out in future changes to the
event subsystem (the signal pipe).
