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Message-ID: <20171230231500.GD6123@localhost.localdomain>
Date: Sat, 30 Dec 2017 21:15:01 -0200
From: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To: Richard Haines <richard_c_haines@...nternet.com>
Cc: selinux@...ho.nsa.gov, netdev@...r.kernel.org,
linux-sctp@...r.kernel.org, linux-security-module@...r.kernel.org,
paul@...l-moore.com, vyasevich@...il.com, nhorman@...driver.com,
sds@...ho.nsa.gov, eparis@...isplace.org, casey@...aufler-ca.com
Subject: Re: [PATCH V4 1/4] security: Add support for SCTP security hooks
On Sat, Dec 30, 2017 at 05:19:26PM +0000, Richard Haines wrote:
> The SCTP security hooks are explained in:
> Documentation/security/LSM-sctp.rst
>
> Signed-off-by: Richard Haines <richard_c_haines@...nternet.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
> ---
> Documentation/security/LSM-sctp.rst | 175 ++++++++++++++++++++++++++++++++++++
> include/linux/lsm_hooks.h | 36 ++++++++
> include/linux/security.h | 25 ++++++
> security/security.c | 22 +++++
> 4 files changed, 258 insertions(+)
> create mode 100644 Documentation/security/LSM-sctp.rst
>
> diff --git a/Documentation/security/LSM-sctp.rst b/Documentation/security/LSM-sctp.rst
> new file mode 100644
> index 0000000..6e5a392
> --- /dev/null
> +++ b/Documentation/security/LSM-sctp.rst
> @@ -0,0 +1,175 @@
> +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.rst``
> +
> +
> +security_sctp_assoc_request()
> +-----------------------------
> +Passes the ``@...` and ``@...nk->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.
> +
> +
> +security_sctp_bind_connect()
> +-----------------------------
> +Passes one or more ipv4/ipv6 addresses to the security module for validation
> +based on the ``@...name`` 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 ``@...name`` 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.
> +
> + SCTP_SOCKOPT_CONNECTX - Allows the allocation of multiple
> + addresses for reaching a peer
> + (multi-homed).
> + 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))::
> +
> + /proc/sys/net/sctp/addip_enable
> + /proc/sys/net/sctp/addip_noauth_enable
> +
> +then the following *_PARAM_*'s are sent to the peer in an
> +ASCONF chunk when the corresponding ``@...name``'s are present::
> +
> + @optname ASCONF Parameter
> + ---------- ------------------
> + SCTP_SOCKOPT_BINDX_ADD -> SCTP_PARAM_ADD_IP
> + SCTP_SET_PEER_PRIMARY_ADDR -> SCTP_PARAM_SET_PRIMARY
> +
> +
> +security_sctp_sk_clone()
> +-------------------------
> +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.
> +
> +
> +security_inet_conn_established()
> +---------------------------------
> +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"
> + ================= =================
> + sctp_sf_do_prm_asoc()
> + 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 --------------------------------------------->
> + sctp_sf_do_5_1B_init()
> + Respond to an INIT chunk.
> + SCTP peer endpoint "A" is
> + asking for an association. Call
> + security_sctp_assoc_request()
> + to set the peer label if first
> + association.
> + 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 |
> + ------------------------------------------------------------------
> +
> +
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index c925812..647e700 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -906,6 +906,33 @@
> * associated with the TUN device's security structure.
> * @security pointer to the TUN devices's security structure.
> *
> + * Security hooks for SCTP
> + *
> + * @sctp_assoc_request:
> + * Passes the @ep and @chunk->skb of the association INIT packet to
> + * the security module.
> + * @ep pointer to sctp endpoint structure.
> + * @skb pointer to skbuff of association packet.
> + * Return 0 on success, error on failure.
> + * @sctp_bind_connect:
> + * Validiate permissions required for each address associated with sock
> + * @sk. Depending on @optname, the addresses will be treated as either
> + * for a connect or bind service. The @addrlen is calculated on each
> + * ipv4 and ipv6 address using sizeof(struct sockaddr_in) or
> + * sizeof(struct sockaddr_in6).
> + * @sk pointer to sock structure.
> + * @optname name of the option to validate.
> + * @address list containing one or more ipv4/ipv6 addresses.
> + * @addrlen total length of address(s).
> + * Return 0 on success, error on failure.
> + * @sctp_sk_clone:
> + * 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.
> + *
> * Security hooks for Infiniband
> *
> * @ib_pkey_access:
> @@ -1631,6 +1658,12 @@ union security_list_options {
> int (*tun_dev_attach_queue)(void *security);
> int (*tun_dev_attach)(struct sock *sk, void *security);
> int (*tun_dev_open)(void *security);
> + int (*sctp_assoc_request)(struct sctp_endpoint *ep,
> + struct sk_buff *skb);
> + int (*sctp_bind_connect)(struct sock *sk, int optname,
> + struct sockaddr *address, int addrlen);
> + void (*sctp_sk_clone)(struct sctp_endpoint *ep, struct sock *sk,
> + struct sock *newsk);
> #endif /* CONFIG_SECURITY_NETWORK */
>
> #ifdef CONFIG_SECURITY_INFINIBAND
> @@ -1869,6 +1902,9 @@ struct security_hook_heads {
> struct list_head tun_dev_attach_queue;
> struct list_head tun_dev_attach;
> struct list_head tun_dev_open;
> + struct list_head sctp_assoc_request;
> + struct list_head sctp_bind_connect;
> + struct list_head sctp_sk_clone;
> #endif /* CONFIG_SECURITY_NETWORK */
> #ifdef CONFIG_SECURITY_INFINIBAND
> struct list_head ib_pkey_access;
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 3107754..2e5ec5c 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -115,6 +115,7 @@ struct xfrm_policy;
> struct xfrm_state;
> struct xfrm_user_sec_ctx;
> struct seq_file;
> +struct sctp_endpoint;
>
> #ifdef CONFIG_MMU
> extern unsigned long mmap_min_addr;
> @@ -1229,6 +1230,11 @@ int security_tun_dev_create(void);
> int security_tun_dev_attach_queue(void *security);
> int security_tun_dev_attach(struct sock *sk, void *security);
> int security_tun_dev_open(void *security);
> +int security_sctp_assoc_request(struct sctp_endpoint *ep, struct sk_buff *skb);
> +int security_sctp_bind_connect(struct sock *sk, int optname,
> + struct sockaddr *address, int addrlen);
> +void security_sctp_sk_clone(struct sctp_endpoint *ep, struct sock *sk,
> + struct sock *newsk);
>
> #else /* CONFIG_SECURITY_NETWORK */
> static inline int security_unix_stream_connect(struct sock *sock,
> @@ -1421,6 +1427,25 @@ static inline int security_tun_dev_open(void *security)
> {
> return 0;
> }
> +
> +static inline int security_sctp_assoc_request(struct sctp_endpoint *ep,
> + struct sk_buff *skb)
> +{
> + return 0;
> +}
> +
> +static inline int security_sctp_bind_connect(struct sock *sk, int optname,
> + struct sockaddr *address,
> + int addrlen)
> +{
> + return 0;
> +}
> +
> +static inline void security_sctp_sk_clone(struct sctp_endpoint *ep,
> + struct sock *sk,
> + struct sock *newsk)
> +{
> +}
> #endif /* CONFIG_SECURITY_NETWORK */
>
> #ifdef CONFIG_SECURITY_INFINIBAND
> diff --git a/security/security.c b/security/security.c
> index 4bf0f57..1400678 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1472,6 +1472,7 @@ void security_inet_conn_established(struct sock *sk,
> {
> call_void_hook(inet_conn_established, sk, skb);
> }
> +EXPORT_SYMBOL(security_inet_conn_established);
>
> int security_secmark_relabel_packet(u32 secid)
> {
> @@ -1527,6 +1528,27 @@ int security_tun_dev_open(void *security)
> }
> EXPORT_SYMBOL(security_tun_dev_open);
>
> +int security_sctp_assoc_request(struct sctp_endpoint *ep, struct sk_buff *skb)
> +{
> + return call_int_hook(sctp_assoc_request, 0, ep, skb);
> +}
> +EXPORT_SYMBOL(security_sctp_assoc_request);
> +
> +int security_sctp_bind_connect(struct sock *sk, int optname,
> + struct sockaddr *address, int addrlen)
> +{
> + return call_int_hook(sctp_bind_connect, 0, sk, optname,
> + address, addrlen);
> +}
> +EXPORT_SYMBOL(security_sctp_bind_connect);
> +
> +void security_sctp_sk_clone(struct sctp_endpoint *ep, struct sock *sk,
> + struct sock *newsk)
> +{
> + call_void_hook(sctp_sk_clone, ep, sk, newsk);
> +}
> +EXPORT_SYMBOL(security_sctp_sk_clone);
> +
> #endif /* CONFIG_SECURITY_NETWORK */
>
> #ifdef CONFIG_SECURITY_INFINIBAND
> --
> 2.14.3
>
> --
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