Audit: Log TIOCSTI

AUDIT_TTY records currently log all data read by processes marked for
TTY input auditing, even if the data was "pushed back" using the TIOCSTI
ioctl, not typed by the user.

This patch records all TIOCSTI calls to disambiguate the input.  It
generates one audit message per character pushed back; considering
TIOCSTI is used very rarely, this simple solution is probably good
enough.  (The only program I could find that uses TIOCSTI is mailx/nail
in "header editing" mode, e.g. using the ~h escape.  mailx is used very
rarely, and the escapes are used even rarer.)

Signed-Off-By: Miloslav Trmac <mitr@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 1412a8d1e58d..db15f9ba7c0b 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2018,6 +2018,7 @@ static int tiocsti(struct tty_struct *tty, char __user *p)
                 return -EPERM;
         if (get_user(ch, p))
                 return -EFAULT;
+        tty_audit_tiocsti(tty, ch);
         ld = tty_ldisc_ref_wait(tty);
         ld->ops->receive_buf(tty, &ch, &mbz, 1);
         tty_ldisc_deref(ld);