Re: [RFC PATCH 1/5] security: Add support for SCTP security hooks

[Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>]

On Tue, Oct 17, 2017 at 03:02:47PM +0100, Richard Haines wrote:
> The SCTP security hooks are explained in:
> Documentation/security/LSM-sctp.txt
> 
> Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
> ---
>  Documentation/security/LSM-sctp.txt | 212 ++++++++++++++++++++++++++++++++++++
>  include/linux/lsm_hooks.h           |  37 +++++++
>  include/linux/security.h            |  27 +++++
>  security/security.c                 |  23 ++++
>  4 files changed, 299 insertions(+)
>  create mode 100644 Documentation/security/LSM-sctp.txt
> 
> diff --git a/Documentation/security/LSM-sctp.txt b/Documentation/security/LSM-sctp.txt
> new file mode 100644
> index 0000000..30fe9b5
> --- /dev/null
> +++ b/Documentation/security/LSM-sctp.txt
> @@ -0,0 +1,212 @@
> +                               SCTP LSM Support
> +                              ==================
> +
> +For security module support, three sctp specific hooks have been implemented:
> +    security_sctp_assoc_request()
> +    security_sctp_bind_connect()
> +    security_sctp_sk_clone()
> +
> +Also the following security hook has been utilised:
> +    security_inet_conn_established()
> +
> +The usage of these hooks are described below with the SELinux implementation
> +described in Documentation/security/SELinux-sctp.txt
> +
> +
> +security_sctp_assoc_request()
> +------------------------------
> +This new hook has been added to net/sctp/sm_statefuns.c where it passes the
> +@ep and @chunk->skb (the association INIT or INIT ACK 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.
> +    @sctp_cid - set to sctp packet type (SCTP_CID_INIT or SCTP_CID_INIT_ACK).
> +
> +The security module performs the following operations:
> +  1) If this is the first association on @ep->base.sk, then set the peer sid
> +     to that in @skb. This will ensure there is only one peer sid assigned
> +     to @ep->base.sk that may support multiple associations.
> +
> +  2) If not the first association, validate the @ep->base.sk peer_sid against
> +     the @skb peer sid to determine whether the association should be allowed
> +     or denied.
> +
> +  3) If @sctp_cid = SCTP_CID_INIT, then set the sctp @ep sid to socket's sid
> +     (from ep->base.sk) with MLS portion taken from @skb peer sid. This will
> +     only be used by SCTP TCP style sockets and peeled off connections as they
> +     cause a new socket to be generated.
> +
> +     If IP security options are configured (CIPSO/CALIPSO), then the ip options
> +     are set on the socket.
> +
> +     To support this hook include/net/sctp/structs.h "struct sctp_endpoint"
> +     has been updated with the following:
> +
> +	/* Security identifiers from incoming (INIT). These are set by
> +	 * security_sctp_assoc_request(). These will only be used by
> +	 * SCTP TCP type sockets and peeled off connections as they
> +	 * cause a new socket to be generated. security_sctp_sk_clone()
> +	 * will then plug these into the new socket.
> +	 */
> +	u32 secid;
> +	u32 peer_secid;
> +
> +
> +security_sctp_bind_connect()
> +-----------------------------
> +This new hook has been added to net/sctp/socket.c and net/sctp/sm_make_chunk.c.
> +It 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
> +                             bind(3).
> +                             sctp_bindx(3) adds a set of bind
> +	                     addresses on a socket.

Nit, indentation issue above.