SELinux: open perm for sock files

When I did open permissions I didn't think any sockets would have an open.
Turns out AF_UNIX sockets can have an open when they are bound to the
filesystem namespace.  This patch adds a new SOCK_FILE__OPEN permission.
It's safe to add this as the open perms are already predicated on
capabilities and capabilities means we have unknown perm handling so
systems should be as backwards compatible as the policy wants them to
be.

https://bugzilla.redhat.com/show_bug.cgi?id=475224

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

security/selinux/hooks.c

@@ -1838,6 +1838,8 @@ static inline u32 open_file_to_av(struct file *file)
 			av |= FIFO_FILE__OPEN;
 		else if (S_ISDIR(mode))
 			av |= DIR__OPEN;
+		else if (S_ISSOCK(mode))
+			av |= SOCK_FILE__OPEN;
 		else
 			printk(KERN_ERR "SELinux: WARNING: inside %s with "
 				"unknown mode:%o\n", __func__, mode);

security/selinux/include/av_perm_to_string.h

@@ -24,6 +24,7 @@
    S_(SECCLASS_CHR_FILE, CHR_FILE__EXECMOD, "execmod")
    S_(SECCLASS_CHR_FILE, CHR_FILE__OPEN, "open")
    S_(SECCLASS_BLK_FILE, BLK_FILE__OPEN, "open")
+   S_(SECCLASS_SOCK_FILE, SOCK_FILE__OPEN, "open")
    S_(SECCLASS_FIFO_FILE, FIFO_FILE__OPEN, "open")
    S_(SECCLASS_FD, FD__USE, "use")
    S_(SECCLASS_TCP_SOCKET, TCP_SOCKET__CONNECTTO, "connectto")

security/selinux/include/av_permissions.h

@@ -174,6 +174,7 @@
 #define SOCK_FILE__SWAPON                         0x00004000UL
 #define SOCK_FILE__QUOTAON                        0x00008000UL
 #define SOCK_FILE__MOUNTON                        0x00010000UL
+#define SOCK_FILE__OPEN                           0x00020000UL
 #define FIFO_FILE__IOCTL                          0x00000001UL
 #define FIFO_FILE__READ                           0x00000002UL
 #define FIFO_FILE__WRITE                          0x00000004UL