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security: Add support for SCTP security hooks

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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>
This commit is contained in:
Richard Haines 2018-02-13 20:53:21 +00:00 committed by Paul Moore
parent 213d7f9477
commit 72e89f5008
4 changed files with 258 additions and 0 deletions
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175
Documentation/security/LSM-sctp.rst Normal file
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@ -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 ``@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.
security_sctp_bind_connect()
-----------------------------
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.
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 ``@optname``'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 |
------------------------------------------------------------------

36
include/linux/lsm_hooks.h
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@ -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:
@ -1665,6 +1692,12 @@ 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
@ -1914,6 +1947,9 @@ 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;

25
include/linux/security.h
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@ -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

22
security/security.c
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@ -1473,6 +1473,7 @@ 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)
{
@ -1528,6 +1529,27 @@ 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