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[patch 1/2] audit: let userspace fully control TTY input auditing

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Remove the code that automatically disables TTY input auditing in processes
that open TTYs when they have no other TTY open; this heuristic was
intended to automatically handle daemons, but it has false positives (e.g.
with sshd) that make it impossible to control TTY input auditing from a PAM
module.  With this patch, TTY input auditing is controlled from user-space
only.

On the other hand, not even for daemons does it make sense to audit "input"
from PTY masters; this data was produced by a program writing to the PTY
slave, and does not represent data entered by the user.

Signed-off-by: Miloslav Trmac <mitr@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Miloslav Trmac
2008-04-18 13:30:14 -07:00
committed by Al Viro
parent 7719e437fa
commit 41126226e1
3 changed files with 5 additions and 59 deletions
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54
drivers/char/tty_audit.c
View File

@@ -233,6 +233,10 @@ void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
if (unlikely(size == 0))
return;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY
&& tty->driver->subtype == PTY_TYPE_MASTER)
return;
buf = tty_audit_buf_get(tty);
if (!buf)
return;
@@ -295,53 +299,3 @@ void tty_audit_push(struct tty_struct *tty)
tty_audit_buf_put(buf);
}
}
/**
* tty_audit_opening - A TTY is being opened.
*
* As a special hack, tasks that close all their TTYs and open new ones
* are assumed to be system daemons (e.g. getty) and auditing is
* automatically disabled for them.
*/
void tty_audit_opening(void)
{
int disable;
disable = 1;
spin_lock_irq(&current->sighand->siglock);
if (current->signal->audit_tty == 0)
disable = 0;
spin_unlock_irq(&current->sighand->siglock);
if (!disable)
return;
task_lock(current);
if (current->files) {
struct fdtable *fdt;
unsigned i;
/*
* We don't take a ref to the file, so we must hold ->file_lock
* instead.
*/
spin_lock(&current->files->file_lock);
fdt = files_fdtable(current->files);
for (i = 0; i < fdt->max_fds; i++) {
struct file *filp;
filp = fcheck_files(current->files, i);
if (filp && is_tty(filp)) {
disable = 0;
break;
}
}
spin_unlock(&current->files->file_lock);
}
task_unlock(current);
if (!disable)
return;
spin_lock_irq(&current->sighand->siglock);
current->signal->audit_tty = 0;
spin_unlock_irq(&current->sighand->siglock);
}