[PATCH] SELinux - fix SCTP socket bug and general IP protocol handling

The following patch updates the way SELinux classifies and handles IP
based protocols.

Currently, IP sockets are classified by SELinux as being either TCP, UDP
or 'Raw', the latter being a default for IP socket that is not TCP or UDP.

The classification code is out of date and uses only the socket type
parameter to socket(2) to determine the class of IP socket.  So, any
socket created with SOCK_STREAM will be classified by SELinux as TCP, and
SOCK_DGRAM as UDP.  Also, other socket types such as SOCK_SEQPACKET and
SOCK_DCCP are currently ignored by SELinux, which classifies them as
generic sockets, which means they don't even get basic IP level checking.

This patch changes the SELinux IP socket classification logic, so that
only an IPPROTO_IP protocol value passed to socket(2) classify the socket
as TCP or UDP.  The patch also drops the check for SOCK_RAW and converts
it into a default, so that socket types like SOCK_DCCP and SOCK_SEQPACKET
are classified as SECCLASS_RAWIP_SOCKET (instead of generic sockets).

Note that protocol-specific support for SCTP, DCCP etc. is not addressed
here, we're just getting these protocols checked at the IP layer.

This fixes a reported problem where SCTP sockets were being recognized as
generic SELinux sockets yet still being passed in one case to an IP level
check, which then fails for generic sockets.

It will also fix bugs where any SOCK_STREAM socket is classified as TCP or
any SOCK_DGRAM socket is classified as UDP.

This patch also unifies the way IP sockets classes are determined in
selinux_socket_bind(), so we use the already calculated value instead of
trying to recalculate it.

Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 24 insertions, 6 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6e4937fe062b..b13be15165f5 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -630,6 +630,16 @@ static inline u16 inode_mode_to_security_class(umode_t mode)
         return SECCLASS_FILE;
 }
 
+static inline int default_protocol_stream(int protocol)
+{
+        return (protocol == IPPROTO_IP || protocol == IPPROTO_TCP);
+}
+
+static inline int default_protocol_dgram(int protocol)
+{
+        return (protocol == IPPROTO_IP || protocol == IPPROTO_UDP);
+}
+
 static inline u16 socket_type_to_security_class(int family, int type, int protocol)
 {
         switch (family) {
@@ -646,10 +656,16 @@ static inline u16 socket_type_to_security_class(int family, int type, int protoc
         case PF_INET6:
                 switch (type) {
                 case SOCK_STREAM:
-                        return SECCLASS_TCP_SOCKET;
+                        if (default_protocol_stream(protocol))
+                                return SECCLASS_TCP_SOCKET;
+                        else
+                                return SECCLASS_RAWIP_SOCKET;
                 case SOCK_DGRAM:
-                        return SECCLASS_UDP_SOCKET;
-                case SOCK_RAW:
+                        if (default_protocol_dgram(protocol))
+                                return SECCLASS_UDP_SOCKET;
+                        else
+                                return SECCLASS_RAWIP_SOCKET;
+                default:
                         return SECCLASS_RAWIP_SOCKET;
                 }
                 break;
@@ -2970,6 +2986,8 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in
 
         /*
          * If PF_INET or PF_INET6, check name_bind permission for the port.
+         * Multiple address binding for SCTP is not supported yet: we just
+         * check the first address now.
          */
         family = sock->sk->sk_family;
         if (family == PF_INET || family == PF_INET6) {
@@ -3014,12 +3032,12 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in
                                 goto out;
                 }
                 
-                switch(sk->sk_protocol) {
-                case IPPROTO_TCP:
+                switch(isec->sclass) {
+                case SECCLASS_TCP_SOCKET:
                         node_perm = TCP_SOCKET__NODE_BIND;
                         break;
                         
-                case IPPROTO_UDP:
+                case SECCLASS_UDP_SOCKET:
                         node_perm = UDP_SOCKET__NODE_BIND;
                         break;