selinux: handle files opened with flags 3 by checking ioctl permission

Handle files opened with flags 3 by checking ioctl permission.

Default to returning FILE__IOCTL from file_to_av() if the f_mode has neither
FMODE_READ nor FMODE_WRITE, and thus check ioctl permission on exec or
transfer, thereby validating such descriptors early as with normal r/w
descriptors and catching leaks of them prior to attempted usage.

Signed-off-by:  Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 41a049f50f58..c2fef7b12dc7 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1630,6 +1630,12 @@ static inline u32 file_to_av(struct file *file)
                 else
                         av |= FILE__WRITE;
         }
+        if (!av) {
+                /*
+                 * Special file opened with flags 3 for ioctl-only use.
+                 */
+                av = FILE__IOCTL;
+        }
 
         return av;
 }