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security: Add support for SCTP security hooks
The SCTP security hooks are explained in: Documentation/security/LSM-sctp.rst Signed-off-by: Richard Haines <richard_c_haines@btinternet.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
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‎Documentation/security/LSM-sctp.rst

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SCTP LSM Support
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================
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For security module support, three SCTP specific hooks have been implemented::
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security_sctp_assoc_request()
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security_sctp_bind_connect()
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security_sctp_sk_clone()
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Also the following security hook has been utilised::
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security_inet_conn_established()
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The usage of these hooks are described below with the SELinux implementation
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described in ``Documentation/security/SELinux-sctp.rst``
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security_sctp_assoc_request()
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-----------------------------
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Passes the ``@ep`` and ``@chunk->skb`` of the association INIT packet to the
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security module. Returns 0 on success, error on failure.
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::
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@ep - pointer to sctp endpoint structure.
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@skb - pointer to skbuff of association packet.
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security_sctp_bind_connect()
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-----------------------------
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Passes one or more ipv4/ipv6 addresses to the security module for validation
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based on the ``@optname`` that will result in either a bind or connect
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service as shown in the permission check tables below.
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Returns 0 on success, error on failure.
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::
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@sk - Pointer to sock structure.
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@optname - Name of the option to validate.
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@address - One or more ipv4 / ipv6 addresses.
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@addrlen - The total length of address(s). This is calculated on each
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ipv4 or ipv6 address using sizeof(struct sockaddr_in) or
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sizeof(struct sockaddr_in6).
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------------------------------------------------------------------
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| BIND Type Checks |
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| @optname | @address contains |
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|----------------------------|-----------------------------------|
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| SCTP_SOCKOPT_BINDX_ADD | One or more ipv4 / ipv6 addresses |
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| SCTP_PRIMARY_ADDR | Single ipv4 or ipv6 address |
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| SCTP_SET_PEER_PRIMARY_ADDR | Single ipv4 or ipv6 address |
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------------------------------------------------------------------
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------------------------------------------------------------------
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| CONNECT Type Checks |
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| @optname | @address contains |
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|----------------------------|-----------------------------------|
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| SCTP_SOCKOPT_CONNECTX | One or more ipv4 / ipv6 addresses |
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| SCTP_PARAM_ADD_IP | One or more ipv4 / ipv6 addresses |
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| SCTP_SENDMSG_CONNECT | Single ipv4 or ipv6 address |
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| SCTP_PARAM_SET_PRIMARY | Single ipv4 or ipv6 address |
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------------------------------------------------------------------
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A summary of the ``@optname`` entries is as follows::
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SCTP_SOCKOPT_BINDX_ADD - Allows additional bind addresses to be
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associated after (optionally) calling
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bind(3).
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sctp_bindx(3) adds a set of bind
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addresses on a socket.
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SCTP_SOCKOPT_CONNECTX - Allows the allocation of multiple
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addresses for reaching a peer
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(multi-homed).
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sctp_connectx(3) initiates a connection
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on an SCTP socket using multiple
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destination addresses.
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SCTP_SENDMSG_CONNECT - Initiate a connection that is generated by a
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sendmsg(2) or sctp_sendmsg(3) on a new asociation.
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SCTP_PRIMARY_ADDR - Set local primary address.
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SCTP_SET_PEER_PRIMARY_ADDR - Request peer sets address as
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association primary.
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SCTP_PARAM_ADD_IP - These are used when Dynamic Address
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SCTP_PARAM_SET_PRIMARY - Reconfiguration is enabled as explained below.
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To support Dynamic Address Reconfiguration the following parameters must be
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enabled on both endpoints (or use the appropriate **setsockopt**\(2))::
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/proc/sys/net/sctp/addip_enable
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/proc/sys/net/sctp/addip_noauth_enable
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then the following *_PARAM_*'s are sent to the peer in an
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ASCONF chunk when the corresponding ``@optname``'s are present::
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@optname ASCONF Parameter
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---------- ------------------
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SCTP_SOCKOPT_BINDX_ADD -> SCTP_PARAM_ADD_IP
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SCTP_SET_PEER_PRIMARY_ADDR -> SCTP_PARAM_SET_PRIMARY
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security_sctp_sk_clone()
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-------------------------
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Called whenever a new socket is created by **accept**\(2)
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(i.e. a TCP style socket) or when a socket is 'peeled off' e.g userspace
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calls **sctp_peeloff**\(3).
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::
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@ep - pointer to current sctp endpoint structure.
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@sk - pointer to current sock structure.
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@sk - pointer to new sock structure.
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security_inet_conn_established()
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---------------------------------
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Called when a COOKIE ACK is received::
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@sk - pointer to sock structure.
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@skb - pointer to skbuff of the COOKIE ACK packet.
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Security Hooks used for Association Establishment
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=================================================
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The following diagram shows the use of ``security_sctp_bind_connect()``,
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``security_sctp_assoc_request()``, ``security_inet_conn_established()`` when
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establishing an association.
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::
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SCTP endpoint "A" SCTP endpoint "Z"
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================= =================
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sctp_sf_do_prm_asoc()
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Association setup can be initiated
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by a connect(2), sctp_connectx(3),
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sendmsg(2) or sctp_sendmsg(3).
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These will result in a call to
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security_sctp_bind_connect() to
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initiate an association to
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SCTP peer endpoint "Z".
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INIT --------------------------------------------->
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sctp_sf_do_5_1B_init()
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Respond to an INIT chunk.
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SCTP peer endpoint "A" is
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asking for an association. Call
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security_sctp_assoc_request()
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to set the peer label if first
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association.
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If not first association, check
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whether allowed, IF so send:
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<----------------------------------------------- INIT ACK
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| ELSE audit event and silently
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| discard the packet.
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|
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COOKIE ECHO ------------------------------------------>
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|
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|
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|
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<------------------------------------------- COOKIE ACK
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| |
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sctp_sf_do_5_1E_ca |
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Call security_inet_conn_established() |
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to set the peer label. |
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| |
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| If SCTP_SOCKET_TCP or peeled off
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| socket security_sctp_sk_clone() is
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| called to clone the new socket.
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| |
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ESTABLISHED ESTABLISHED
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| |
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------------------------------------------------------------------
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| Association Established |
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------------------------------------------------------------------
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‎include/linux/lsm_hooks.h

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* associated with the TUN device's security structure.
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* @security pointer to the TUN devices's security structure.
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*
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* Security hooks for SCTP
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*
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* @sctp_assoc_request:
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* Passes the @ep and @chunk->skb of the association INIT packet to
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* the security module.
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* @ep pointer to sctp endpoint structure.
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* @skb pointer to skbuff of association packet.
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* Return 0 on success, error on failure.
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* @sctp_bind_connect:
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* Validiate permissions required for each address associated with sock
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* @sk. Depending on @optname, the addresses will be treated as either
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* for a connect or bind service. The @addrlen is calculated on each
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* ipv4 and ipv6 address using sizeof(struct sockaddr_in) or
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* sizeof(struct sockaddr_in6).
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* @sk pointer to sock structure.
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* @optname name of the option to validate.
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* @address list containing one or more ipv4/ipv6 addresses.
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* @addrlen total length of address(s).
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* Return 0 on success, error on failure.
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* @sctp_sk_clone:
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* Called whenever a new socket is created by accept(2) (i.e. a TCP
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* style socket) or when a socket is 'peeled off' e.g userspace
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* calls sctp_peeloff(3).
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* @ep pointer to current sctp endpoint structure.
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* @sk pointer to current sock structure.
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* @sk pointer to new sock structure.
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*
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* Security hooks for Infiniband
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*
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* @ib_pkey_access:
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int (*tun_dev_attach_queue)(void *security);
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int (*tun_dev_attach)(struct sock *sk, void *security);
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int (*tun_dev_open)(void *security);
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int (*sctp_assoc_request)(struct sctp_endpoint *ep,
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struct sk_buff *skb);
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int (*sctp_bind_connect)(struct sock *sk, int optname,
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struct sockaddr *address, int addrlen);
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void (*sctp_sk_clone)(struct sctp_endpoint *ep, struct sock *sk,
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struct sock *newsk);
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#endif /* CONFIG_SECURITY_NETWORK */
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#ifdef CONFIG_SECURITY_INFINIBAND
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struct list_head tun_dev_attach_queue;
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struct list_head tun_dev_attach;
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struct list_head tun_dev_open;
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struct list_head sctp_assoc_request;
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struct list_head sctp_bind_connect;
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struct list_head sctp_sk_clone;
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#endif /* CONFIG_SECURITY_NETWORK */
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#ifdef CONFIG_SECURITY_INFINIBAND
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struct list_head ib_pkey_access;

‎include/linux/security.h

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struct xfrm_state;
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struct xfrm_user_sec_ctx;
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struct seq_file;
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struct sctp_endpoint;
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#ifdef CONFIG_MMU
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extern unsigned long mmap_min_addr;
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int security_tun_dev_attach_queue(void *security);
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int security_tun_dev_attach(struct sock *sk, void *security);
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int security_tun_dev_open(void *security);
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int security_sctp_assoc_request(struct sctp_endpoint *ep, struct sk_buff *skb);
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int security_sctp_bind_connect(struct sock *sk, int optname,
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struct sockaddr *address, int addrlen);
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void security_sctp_sk_clone(struct sctp_endpoint *ep, struct sock *sk,
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struct sock *newsk);
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#else /* CONFIG_SECURITY_NETWORK */
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static inline int security_unix_stream_connect(struct sock *sock,
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{
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return 0;
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}
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static inline int security_sctp_assoc_request(struct sctp_endpoint *ep,
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struct sk_buff *skb)
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{
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return 0;
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}
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static inline int security_sctp_bind_connect(struct sock *sk, int optname,
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struct sockaddr *address,
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int addrlen)
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{
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return 0;
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}
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static inline void security_sctp_sk_clone(struct sctp_endpoint *ep,
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struct sock *sk,
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struct sock *newsk)
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{
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}
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#endif /* CONFIG_SECURITY_NETWORK */
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#ifdef CONFIG_SECURITY_INFINIBAND

‎security/security.c

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{
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call_void_hook(inet_conn_established, sk, skb);
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}
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EXPORT_SYMBOL(security_inet_conn_established);
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int security_secmark_relabel_packet(u32 secid)
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{
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}
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EXPORT_SYMBOL(security_tun_dev_open);
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int security_sctp_assoc_request(struct sctp_endpoint *ep, struct sk_buff *skb)
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{
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return call_int_hook(sctp_assoc_request, 0, ep, skb);
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}
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EXPORT_SYMBOL(security_sctp_assoc_request);
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int security_sctp_bind_connect(struct sock *sk, int optname,
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struct sockaddr *address, int addrlen)
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{
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return call_int_hook(sctp_bind_connect, 0, sk, optname,
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address, addrlen);
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}
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EXPORT_SYMBOL(security_sctp_bind_connect);
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void security_sctp_sk_clone(struct sctp_endpoint *ep, struct sock *sk,
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struct sock *newsk)
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{
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call_void_hook(sctp_sk_clone, ep, sk, newsk);
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}
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EXPORT_SYMBOL(security_sctp_sk_clone);
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#endif /* CONFIG_SECURITY_NETWORK */
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#ifdef CONFIG_SECURITY_INFINIBAND

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