tty: audit: Ignore current association for audit push
In canonical read mode, each line read and logged is pushed separately
with tty_audit_push(). For all single-threaded processes and multi-threaded
processes reading from only one tty, this patch has no effect; the last line
read will still be the entry pushed to the audit log because the tty
association cannot have changed between tty_audit_add_data() and
tty_audit_push().
For multi-threaded processes reading from different ttys concurrently,
the audit log will have mixed log entries anyway. Consider two ttys
audited concurrently:
CPU0 CPU1
---------- ------------
tty_audit_add_data(ttyA)
tty_audit_add_data(ttyB)
tty_audit_push()
tty_audit_add_data(ttyB)
tty_audit_push()
This patch will now cause the ttyB output to be split into separate
audit log entries.
However, this possibility is equally likely without this patch:
CPU0 CPU1
---------- ------------
tty_audit_add_data(ttyB)
tty_audit_add_data(ttyA)
tty_audit_push()
tty_audit_add_data(ttyB)
tty_audit_push()
Mixed canonical and non-canonical reads have similar races.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 4fbc5de..8272069 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2072,7 +2072,7 @@
ldata->line_start = ldata->read_tail;
else
ldata->push = 0;
- tty_audit_push(tty);
+ tty_audit_push();
}
return 0;
}
diff --git a/drivers/tty/tty_audit.c b/drivers/tty/tty_audit.c
index 5f65653..5ae4839 100644
--- a/drivers/tty/tty_audit.c
+++ b/drivers/tty/tty_audit.c
@@ -313,9 +313,9 @@
/**
* tty_audit_push - Push buffered data out
*
- * Make sure no audit data is pending for @tty on the current process.
+ * Make sure no audit data is pending on the current process.
*/
-void tty_audit_push(struct tty_struct *tty)
+void tty_audit_push(void)
{
struct tty_audit_buf *buf;
unsigned long flags;
@@ -331,13 +331,8 @@
spin_unlock_irqrestore(¤t->sighand->siglock, flags);
if (buf) {
- int major, minor;
-
- major = tty->driver->major;
- minor = tty->driver->minor_start + tty->index;
mutex_lock(&buf->mutex);
- if (buf->major == major && buf->minor == minor)
- tty_audit_buf_push(buf);
+ tty_audit_buf_push(buf);
mutex_unlock(&buf->mutex);
tty_audit_buf_put(buf);
}