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/security/selinux/hooks.c b/security/selinux/hooks.c
index 00b5011..4dfbcea 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2088,15 +2088,19 @@
return (atsecure || cap_bprm_secureexec(bprm));
}
+static int match_file(const void *p, struct file *file, unsigned fd)
+{
+ return file_has_perm(p, file, file_to_av(file)) ? fd + 1 : 0;
+}
+
/* Derived from fs/exec.c:flush_old_files. */
static inline void flush_unauthorized_files(const struct cred *cred,
struct files_struct *files)
{
struct file *file, *devnull = NULL;
struct tty_struct *tty;
- struct fdtable *fdt;
- long j = -1;
int drop_tty = 0;
+ unsigned n;
tty = get_current_tty();
if (tty) {
@@ -2123,41 +2127,24 @@
no_tty();
/* Revalidate access to inherited open files. */
- spin_lock(&files->file_lock);
- for (;;) {
- unsigned long set, i;
- j++;
- i = j * BITS_PER_LONG;
- fdt = files_fdtable(files);
- if (i >= fdt->max_fds)
- break;
- set = fdt->open_fds[j];
- if (!set)
- continue;
- spin_unlock(&files->file_lock);
- for ( ; set ; i++, set >>= 1) {
- if (!(set & 1))
- continue;
- file = fget(i);
- if (!file)
- continue;
- if (file_has_perm(cred, file, file_to_av(file))) {
- if (devnull) {
- get_file(devnull);
- } else {
- devnull = dentry_open(&selinux_null,
- O_RDWR, cred);
- if (IS_ERR(devnull))
- devnull = NULL;
- }
- replace_fd(i, devnull, 0);
- }
- fput(file);
- }
- spin_lock(&files->file_lock);
+ n = iterate_fd(files, 0, match_file, cred);
+ if (!n) /* none found? */
+ return;
+ devnull = dentry_open(&selinux_null, O_RDWR, cred);
+ if (!IS_ERR(devnull)) {
+ /* replace all the matching ones with this */
+ do {
+ get_file(devnull);
+ replace_fd(n - 1, devnull, 0);
+ } while ((n = iterate_fd(files, n, match_file, cred)) != 0);
+ fput(devnull);
+ } else {
+ /* just close all the matching ones */
+ do {
+ replace_fd(n - 1, NULL, 0);
+ } while ((n = iterate_fd(files, n, match_file, cred)) != 0);
}
- spin_unlock(&files->file_lock);
}
/*