new helper: iterate_fd()
iterates through the opened files in given descriptor table,
calling a supplied function; we stop once non-zero is returned.
Callback gets struct file *, descriptor number and const void *
argument passed to iterator. It is called with files->file_lock
held, so it is not allowed to block.
tty_io, netprio_cgroup and selinux flush_unauthorized_files()
converted to its use.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index b425c79..71d95cf 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2791,6 +2791,13 @@
}
#endif
+static int this_tty(const void *t, struct file *file, unsigned fd)
+{
+ if (likely(file->f_op->read != tty_read))
+ return 0;
+ return file_tty(file) != t ? 0 : fd + 1;
+}
+
/*
* This implements the "Secure Attention Key" --- the idea is to
* prevent trojan horses by killing all processes associated with this
@@ -2818,8 +2825,6 @@
struct task_struct *g, *p;
struct pid *session;
int i;
- struct file *filp;
- struct fdtable *fdt;
if (!tty)
return;
@@ -2849,27 +2854,12 @@
continue;
}
task_lock(p);
- if (p->files) {
- /*
- * We don't take a ref to the file, so we must
- * hold ->file_lock instead.
- */
- spin_lock(&p->files->file_lock);
- fdt = files_fdtable(p->files);
- for (i = 0; i < fdt->max_fds; i++) {
- filp = fcheck_files(p->files, i);
- if (!filp)
- continue;
- if (filp->f_op->read == tty_read &&
- file_tty(filp) == tty) {
- printk(KERN_NOTICE "SAK: killed process %d"
- " (%s): fd#%d opened to the tty\n",
- task_pid_nr(p), p->comm, i);
- force_sig(SIGKILL, p);
- break;
- }
- }
- spin_unlock(&p->files->file_lock);
+ i = iterate_fd(p->files, 0, this_tty, tty);
+ if (i != 0) {
+ printk(KERN_NOTICE "SAK: killed process %d"
+ " (%s): fd#%d opened to the tty\n",
+ task_pid_nr(p), p->comm, i - 1);
+ force_sig(SIGKILL, p);
}
task_unlock(p);
} while_each_thread(g, p);