SCTP LSM Support

For security module support, three SCTP specific hooks have been implemented:


Also the following security hook has been utilised:


The usage of these hooks are described below with the SELinux implementation described in Documentation/security/SELinux-sctp.rst


Passes the @ep and @chunk->skb of the association INIT packet to the security module. Returns 0 on success, error on failure.

@ep - pointer to sctp endpoint structure.
@skb - pointer to skbuff of association packet.


Passes one or more ipv4/ipv6 addresses to the security module for validation based on the @optname that will result in either a bind or connect service as shown in the permission check tables below. Returns 0 on success, error on failure.

  @sk      - Pointer to sock structure.
  @optname - Name of the option to validate.
  @address - One or more ipv4 / ipv6 addresses.
  @addrlen - The total length of address(s). This is calculated on each
             ipv4 or ipv6 address using sizeof(struct sockaddr_in) or
             sizeof(struct sockaddr_in6).

|                     BIND Type Checks                           |
|       @optname             |         @address contains         |
| SCTP_SOCKOPT_BINDX_ADD     | One or more ipv4 / ipv6 addresses |
| SCTP_PRIMARY_ADDR          | Single ipv4 or ipv6 address       |
| SCTP_SET_PEER_PRIMARY_ADDR | Single ipv4 or ipv6 address       |

|                   CONNECT Type Checks                          |
|       @optname             |         @address contains         |
| SCTP_SOCKOPT_CONNECTX      | One or more ipv4 / ipv6 addresses |
| SCTP_PARAM_ADD_IP          | One or more ipv4 / ipv6 addresses |
| SCTP_SENDMSG_CONNECT       | Single ipv4 or ipv6 address       |
| SCTP_PARAM_SET_PRIMARY     | Single ipv4 or ipv6 address       |

A summary of the @optname entries is as follows:

SCTP_SOCKOPT_BINDX_ADD - Allows additional bind addresses to be
                         associated after (optionally) calling
                         sctp_bindx(3) adds a set of bind
                         addresses on a socket.

SCTP_SOCKOPT_CONNECTX - Allows the allocation of multiple
                        addresses for reaching a peer
                        sctp_connectx(3) initiates a connection
                        on an SCTP socket using multiple
                        destination addresses.

SCTP_SENDMSG_CONNECT  - Initiate a connection that is generated by a
                        sendmsg(2) or sctp_sendmsg(3) on a new asociation.

SCTP_PRIMARY_ADDR     - Set local primary address.

SCTP_SET_PEER_PRIMARY_ADDR - Request peer sets address as
                             association primary.

SCTP_PARAM_ADD_IP          - These are used when Dynamic Address
SCTP_PARAM_SET_PRIMARY     - Reconfiguration is enabled as explained below.

To support Dynamic Address Reconfiguration the following parameters must be enabled on both endpoints (or use the appropriate setsockopt(2)):


then the following _PARAM_‘s are sent to the peer in an ASCONF chunk when the corresponding @optname‘s are present:

      @optname                      ASCONF Parameter
     ----------                    ------------------


Called whenever a new socket is created by accept(2) (i.e. a TCP style socket) or when a socket is ‘peeled off’ e.g userspace calls sctp_peeloff(3).

@ep - pointer to current sctp endpoint structure.
@sk - pointer to current sock structure.
@sk - pointer to new sock structure.


Called when a COOKIE ACK is received:

@sk  - pointer to sock structure.
@skb - pointer to skbuff of the COOKIE ACK packet.

Security Hooks used for Association Establishment

The following diagram shows the use of security_sctp_bind_connect(), security_sctp_assoc_request(), security_inet_conn_established() when establishing an association.

     SCTP endpoint "A"                                SCTP endpoint "Z"
     =================                                =================
Association setup can be initiated
by a connect(2), sctp_connectx(3),
sendmsg(2) or sctp_sendmsg(3).
These will result in a call to
security_sctp_bind_connect() to
initiate an association to
SCTP peer endpoint "Z".
        INIT --------------------------------------------->
                                                Respond to an INIT chunk.
                                            SCTP peer endpoint "A" is
                                            asking for an association. Call
                                            to set the peer label if first
                                            If not first association, check
                                            whether allowed, IF so send:
         <----------------------------------------------- INIT ACK
         |                                  ELSE audit event and silently
         |                                       discard the packet.
   COOKIE ECHO ------------------------------------------>
         <------------------------------------------- COOKIE ACK
         |                                               |
   sctp_sf_do_5_1E_ca                                    |
Call security_inet_conn_established()                    |
to set the peer label.                                   |
         |                                               |
         |                               If SCTP_SOCKET_TCP or peeled off
         |                               socket security_sctp_sk_clone() is
         |                               called to clone the new socket.
         |                                               |
     ESTABLISHED                                    ESTABLISHED
         |                                               |
   |                     Association Established                    |