audit: add an option to control logging of passwords with pam_tty_audit

Most commands are entered one line at a time and processed as complete lines
in non-canonical mode.  Commands that interactively require a password, enter
canonical mode to do this while shutting off echo.  This pair of features
(icanon and !echo) can be used to avoid logging passwords by audit while still
logging the rest of the command.

Adding a member (log_passwd) to the struct audit_tty_status passed in by
pam_tty_audit allows control of canonical mode without echo per task.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/tty/tty_audit.c b/drivers/tty/tty_audit.c
index 755d418..5f38682 100644
--- a/drivers/tty/tty_audit.c
+++ b/drivers/tty/tty_audit.c
@@ -138,6 +138,7 @@ void tty_audit_fork(struct signal_struct *sig)
 
 	spin_lock_irqsave(&current->sighand->siglock, flags);
 	sig->audit_tty = current->signal->audit_tty;
+	sig->audit_tty_log_passwd = current->signal->audit_tty_log_passwd;
 	spin_unlock_irqrestore(&current->sighand->siglock, flags);
 }
 
@@ -275,10 +276,18 @@ void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
 {
 	struct tty_audit_buf *buf;
 	int major, minor;
+	int audit_log_tty_passwd;
+	unsigned long flags;
 
 	if (unlikely(size == 0))
 		return;
 
+	spin_lock_irqsave(&current->sighand->siglock, flags);
+	audit_log_tty_passwd = current->signal->audit_tty_log_passwd;
+	spin_unlock_irqrestore(&current->sighand->siglock, flags);
+	if (!audit_log_tty_passwd && icanon && !L_ECHO(tty))
+		return;
+
 	if (tty->driver->type == TTY_DRIVER_TYPE_PTY
 	    && tty->driver->subtype == PTY_TYPE_MASTER)
 		return;