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Message-Id: <80e6a4fb06ec6b8f81577abd11827d75dd6689ce.1513940757.git.marcelo.leitner@gmail.com>
Date: Fri, 22 Dec 2017 11:05:16 -0200
From: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To: selinux@...ho.nsa.gov, netdev@...r.kernel.org,
linux-sctp@...r.kernel.org, linux-security-module@...r.kernel.org
Cc: paul@...l-moore.com, vyasevich@...il.com, nhorman@...driver.com,
sds@...ho.nsa.gov, eparis@...isplace.org,
marcelo.leitner@...il.com, richard_c_haines@...nternet.com
Subject: [PATCH v3 1/4] security: Add support for SCTP security hooks
From: Richard Haines <richard_c_haines@...nternet.com>
The SCTP security hooks are explained in:
Documentation/security/LSM-sctp.rst
Signed-off-by: Richard Haines <richard_c_haines@...nternet.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
---
Documentation/security/LSM-sctp.rst | 194 ++++++++++++++++++++++++++++++++++++
include/linux/lsm_hooks.h | 35 +++++++
include/linux/security.h | 25 +++++
security/security.c | 22 ++++
4 files changed, 276 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 0000000000000000000000000000000000000000..61373672ce9f63bbd52d953500f44cdf3427c3f0
--- /dev/null
+++ b/Documentation/security/LSM-sctp.rst
@@ -0,0 +1,194 @@
+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()
+-----------------------------
+This new hook passes the ``@...` and ``@...nk->skb`` (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.
+
+The security module performs the following operations:
+ IF this is the first association on ``@ep->base.sk``, then set the peer
+ sid to that in ``@...``. This will ensure there is only one peer sid
+ assigned to ``@ep->base.sk`` that may support multiple associations.
+
+ ELSE validate the ``@ep->base.sk peer_sid`` against the ``@skb peer sid``
+ to determine whether the association should be allowed or denied.
+
+ Set the sctp ``@ep sid`` to socket's sid (from ``ep->base.sk``) with
+ MLS portion taken from ``@skb peer sid``. This will 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.
+
+
+security_sctp_bind_connect()
+-----------------------------
+This new hook 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()
+-------------------------
+This new hook is 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). ``security_sctp_sk_clone()`` will set the new
+sockets sid and peer sid to that contained in the ``@ep sid`` and
+``@ep peer sid`` respectively.
+::
+
+ @ep - pointer to old sctp endpoint structure.
+ @sk - pointer to old sock structure.
+ @sk - pointer to new sock structure.
+
+
+security_inet_conn_established()
+---------------------------------
+This hook has been added to the receive COOKIE ACK processing where it sets
+the connection's peer sid to that in ``@...``::
+
+ @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_connect_bind()``,
+``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 correct peer sid. |
+ | |
+ | 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 c9258124e41757187cdb8b2f83c5901966345902..92ee9c6c604212ce38590bd2e5fcba55617b9c04 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -906,6 +906,32 @@
* associated with the TUN device's security structure.
* @security pointer to the TUN devices's security structure.
*
+ * Security hooks for SCTP
+ *
+ * @sctp_assoc_request:
+ * If first association, then set the peer sid to that in @skb. If
+ * @sctp_cid is from an INIT chunk, then set the sctp endpoint sid to
+ * socket's sid (ep->base.sk) with MLS portion taken from peer sid.
+ * @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:
+ * Sets the new child socket's sid to the old endpoint sid.
+ * @ep pointer to old sctp endpoint structure.
+ * @sk pointer to old sock structure.
+ * @sk pointer to new sock structure.
+ *
* Security hooks for Infiniband
*
* @ib_pkey_access:
@@ -1631,6 +1657,12 @@ 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 +1901,9 @@ 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 ce6265960d6c430a90e1ad3c3749d0a438ecaca9..51f6cc2417f278674dfbd434587af805cb0c03d3 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 4bf0f571b4ef94df1d3c44b7fed6b7b651c1924f..1400678f6b72b36123f2fa2b909f35d257a62cd4 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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