Re: [PATCH, v2] Audit: Add TTY input auditing

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 08 Jun 2007 06:23:23 +0200 Miloslav Trmac <mitr@redhat.com> wrote:

> From: Miloslav Trmac <mitr@redhat.com>
> 
> Add TTY input auditing, used to audit system administrator's actions.
> TTY input auditing works on a higher level than auditing all system
> calls within the session, which would produce an overwhelming amount of
> mostly useless audit events.
> 
> Add an "audit_tty" attribute, inherited across fork ().  Data read from
> TTYs by process with the attribute is sent to the audit subsystem by the
> kernel.  The audit netlink interface is extended to allow modifying the
> audit_tty attribute, and to allow sending explanatory audit events from
> user-space (for example, a shell might send an event containing the
> final command, after the interactive command-line editing and history
> expansion is performed, which might be difficult to decipher from the
> TTY input alone).
> 
> Because the "audit_tty" attribute is inherited across fork (), it would
> be set e.g. for sshd restarted within an audited session.  To prevent
> this, the audit_tty attribute is cleared when a process with no open TTY
> file descriptors (e.g. after daemon startup) opens a TTY.
> 
> See https://www.redhat.com/archives/linux-audit/2007-June/msg00000.html
> for a more detailed rationale document for an older version of this patch.
> 
> ---
> Changes since the previous patch:
> * use spin_lock_irq() for siglock
> * add an is_tty() function instead of checking f_op->read from n_tty.c;
>   handle hung TTYs
> * replace the audit_tty bit field by a whole word to avoid the risk of
>   incorrect locking
> * move most new code from n_tty.c to a separate file
> * fix coding style violations
> * fix compilation with !CONFIG_AUDIT
> 

> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index d58e74b..d9d734c 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -506,6 +506,8 @@ struct signal_struct {
>  #ifdef CONFIG_TASKSTATS
>  	struct taskstats *stats;
>  #endif
> +	unsigned audit_tty;
> +	struct tty_audit_buf *tty_audit_buf;
>  };

Can we ifdef these?