// SPDX-License-Identifier: GPL-2.0-or-later
/*
* SELinux NetLabel Support
*
* This file provides the necessary glue to tie NetLabel into the SELinux
* subsystem.
*
* Author: Paul Moore <[email protected]>
*/
/*
* (c) Copyright Hewlett-Packard Development Company, L.P., 2007, 2008
*/
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/gfp.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/lsm_hooks.h>
#include <net/sock.h>
#include <net/netlabel.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include "objsec.h"
#include "security.h"
#include "netlabel.h"
/**
* selinux_netlbl_sidlookup_cached - Cache a SID lookup
* @skb: the packet
* @family: the packet's address family
* @secattr: the NetLabel security attributes
* @sid: the SID
*
* Description:
* Query the SELinux security server to lookup the correct SID for the given
* security attributes. If the query is successful, cache the result to speed
* up future lookups. Returns zero on success, negative values on failure.
*
*/
static int selinux_netlbl_sidlookup_cached(struct sk_buff *skb,
u16 family,
struct netlbl_lsm_secattr *secattr,
u32 *sid)
{
int rc;
rc = security_netlbl_secattr_to_sid(secattr, sid);
if (rc == 0 &&
(secattr->flags & NETLBL_SECATTR_CACHEABLE) &&
(secattr->flags & NETLBL_SECATTR_CACHE))
netlbl_cache_add(skb, family, secattr);
return rc;
}
/**
* selinux_netlbl_sock_genattr - Generate the NetLabel socket secattr
* @sk: the socket
*
* Description:
* Generate the NetLabel security attributes for a socket, making full use of
* the socket's attribute cache. Returns a pointer to the security attributes
* on success, or an ERR_PTR on failure.
*
*/
static struct netlbl_lsm_secattr *selinux_netlbl_sock_genattr(struct sock *sk)
{
int rc;
struct sk_security_struct *sksec = selinux_sock(sk);
struct netlbl_lsm_secattr *secattr;
if (sksec->nlbl_secattr != NULL)
return sksec->nlbl_secattr;
secattr = netlbl_secattr_alloc(GFP_ATOMIC);
if (secattr == NULL)
return ERR_PTR(-ENOMEM);
rc = security_netlbl_sid_to_secattr(sksec->sid, secattr);
if (rc != 0) {
netlbl_secattr_free(secattr);
return ERR_PTR(rc);
}
sksec->nlbl_secattr = secattr;
return secattr;
}
/**
* selinux_netlbl_sock_getattr - Get the cached NetLabel secattr
* @sk: the socket
* @sid: the SID
*
* Query the socket's cached secattr and if the SID matches the cached value
* return the cache, otherwise return NULL.
*
*/
static struct netlbl_lsm_secattr *selinux_netlbl_sock_getattr(
const struct sock *sk,
u32 sid)
{
struct sk_security_struct *sksec = selinux_sock(sk);
struct netlbl_lsm_secattr *secattr = sksec->nlbl_secattr;
if (secattr == NULL)
return NULL;
if ((secattr->flags & NETLBL_SECATTR_SECID) &&
(secattr->attr.secid == sid))
return secattr;
return NULL;
}
/**
* selinux_netlbl_cache_invalidate - Invalidate the NetLabel cache
*
* Description:
* Invalidate the NetLabel security attribute mapping cache.
*
*/
void selinux_netlbl_cache_invalidate(void)
{
netlbl_cache_invalidate();
}
/**
* selinux_netlbl_err - Handle a NetLabel packet error
* @skb: the packet
* @family: the packet's address family
* @error: the error code
* @gateway: true if host is acting as a gateway, false otherwise
*
* Description:
* When a packet is dropped due to a call to avc_has_perm() pass the error
* code to the NetLabel subsystem so any protocol specific processing can be
* done. This is safe to call even if you are unsure if NetLabel labeling is
* present on the packet, NetLabel is smart enough to only act when it should.
*
*/
void selinux_netlbl_err(struct sk_buff *skb, u16 family, int error, int gateway)
{
netlbl_skbuff_err(skb, family, error, gateway);
}
/**
* selinux_netlbl_sk_security_free - Free the NetLabel fields
* @sksec: the sk_security_struct
*
* Description:
* Free all of the memory in the NetLabel fields of a sk_security_struct.
*
*/
void selinux_netlbl_sk_security_free(struct sk_security_struct *sksec)
{
if (!sksec->nlbl_secattr)
return;
netlbl_secattr_free(sksec->nlbl_secattr);
sksec->nlbl_secattr = NULL;
sksec->nlbl_state = NLBL_UNSET;
}
/**
* selinux_netlbl_sk_security_reset - Reset the NetLabel fields
* @sksec: the sk_security_struct
*
* Description:
* Called when the NetLabel state of a sk_security_struct needs to be reset.
* The caller is responsible for all the NetLabel sk_security_struct locking.
*
*/
void selinux_netlbl_sk_security_reset(struct sk_security_struct *sksec)
{
sksec->nlbl_state = NLBL_UNSET;
}
/**
* selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel
* @skb: the packet
* @family: protocol family
* @type: NetLabel labeling protocol type
* @sid: the SID
*
* Description:
* Call the NetLabel mechanism to get the security attributes of the given
* packet and use those attributes to determine the correct context/SID to
* assign to the packet. Returns zero on success, negative values on failure.
*
*/
int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
u16 family,
u32 *type,
u32 *sid)
{
int rc;
struct netlbl_lsm_secattr secattr;
if (!netlbl_enabled()) {
*type = NETLBL_NLTYPE_NONE;
*sid = SECSID_NULL;
return 0;
}
netlbl_secattr_init(&secattr);
rc = netlbl_skbuff_getattr(skb, family, &secattr);
if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
rc = selinux_netlbl_sidlookup_cached(skb, family,
&secattr, sid);
else
*sid = SECSID_NULL;
*type = secattr.type;
netlbl_secattr_destroy(&secattr);
return rc;
}
/**
* selinux_netlbl_skbuff_setsid - Set the NetLabel on a packet given a sid
* @skb: the packet
* @family: protocol family
* @sid: the SID
*
* Description
* Call the NetLabel mechanism to set the label of a packet using @sid.
* Returns zero on success, negative values on failure.
*
*/
int selinux_netlbl_skbuff_setsid(struct sk_buff *skb,
u16 family,
u32 sid)
{
int rc;
struct netlbl_lsm_secattr secattr_storage;
struct netlbl_lsm_secattr *secattr = NULL;
struct sock *sk;
/* if this is a locally generated packet check to see if it is already
* being labeled by it's parent socket, if it is just exit */
sk = skb_to_full_sk(skb);
if (sk != NULL) {
struct sk_security_struct *sksec = selinux_sock(sk);
if (sksec->nlbl_state != NLBL_REQSKB)
return 0;
secattr = selinux_netlbl_sock_getattr(sk, sid);
}
if (secattr == NULL) {
secattr = &secattr_storage;
netlbl_secattr_init(secattr);
rc = security_netlbl_sid_to_secattr(sid, secattr);
if (rc != 0)
goto skbuff_setsid_return;
}
rc = netlbl_skbuff_setattr(skb, family, secattr);
skbuff_setsid_return:
if (secattr == &secattr_storage)
netlbl_secattr_destroy(secattr);
return rc;
}
/**
* selinux_netlbl_sctp_assoc_request - Label an incoming sctp association.
* @asoc: incoming association.
* @skb: the packet.
*
* Description:
* A new incoming connection is represented by @asoc, ......
* Returns zero on success, negative values on failure.
*
*/
int selinux_netlbl_sctp_assoc_request(struct sctp_association *asoc,
struct sk_buff *skb)
{
int rc;
struct netlbl_lsm_secattr secattr;
struct sk_security_struct *sksec = selinux_sock(asoc->base.sk);
struct sockaddr_in addr4;
struct sockaddr_in6 addr6;
if (asoc->base.sk->sk_family != PF_INET &&
asoc->base.sk->sk_family != PF_INET6)
return 0;
netlbl_secattr_init(&secattr);
rc = security_netlbl_sid_to_secattr(asoc->secid, &secattr);
if (rc != 0)
goto assoc_request_return;
/* Move skb hdr address info to a struct sockaddr and then call
* netlbl_conn_setattr().
*/
if (ip_hdr(skb)->version == 4) {
addr4.sin_family = AF_INET;
addr4.sin_addr.s_addr = ip_hdr(skb)->saddr;
rc = netlbl_conn_setattr(asoc->base.sk, (void *)&addr4, &secattr);
} else if (IS_ENABLED(CONFIG_IPV6) && ip_hdr(skb)->version == 6) {
addr6.sin6_family = AF_INET6;
addr6.sin6_addr = ipv6_hdr(skb)->saddr;
rc = netlbl_conn_setattr(asoc->base.sk, (void *)&addr6, &secattr);
} else {
rc = -EAFNOSUPPORT;
}
if (rc == 0)
sksec->nlbl_state = NLBL_LABELED;
assoc_request_return:
netlbl_secattr_destroy(&secattr);
return rc;
}
/**
* selinux_netlbl_inet_conn_request - Label an incoming stream connection
* @req: incoming connection request socket
* @family: the request socket's address family
*
* Description:
* A new incoming connection request is represented by @req, we need to label
* the new request_sock here and the stack will ensure the on-the-wire label
* will get preserved when a full sock is created once the connection handshake
* is complete. Returns zero on success, negative values on failure.
*
*/
int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family)
{
int rc;
struct netlbl_lsm_secattr secattr;
if (family != PF_INET && family != PF_INET6)
return 0;
netlbl_secattr_init(&secattr);
rc = security_netlbl_sid_to_secattr(req->secid, &secattr);
if (rc != 0)
goto inet_conn_request_return;
rc = netlbl_req_setattr(req, &secattr);
inet_conn_request_return:
netlbl_secattr_destroy(&secattr);
return rc;
}
/**
* selinux_netlbl_inet_csk_clone - Initialize the newly created sock
* @sk: the new sock
* @family: the sock's address family
*
* Description:
* A new connection has been established using @sk, we've already labeled the
* socket via the request_sock struct in selinux_netlbl_inet_conn_request() but
* we need to set the NetLabel state here since we now have a sock structure.
*
*/
void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family)
{
struct sk_security_struct *sksec = selinux_sock(sk);
if (family == PF_INET || family == PF_INET6)
sksec->nlbl_state = NLBL_LABELED;
else
sksec->nlbl_state = NLBL_UNSET;
}
/**
* selinux_netlbl_sctp_sk_clone - Copy state to the newly created sock
* @sk: current sock
* @newsk: the new sock
*
* Description:
* Called whenever a new socket is created by accept(2) or sctp_peeloff(3).
*/
void selinux_netlbl_sctp_sk_clone(struct sock *sk, struct sock *newsk)
{
struct sk_security_struct *sksec = selinux_sock(sk);
struct sk_security_struct *newsksec = selinux_sock(newsk);
newsksec->nlbl_state = sksec->nlbl_state;
}
/**
* selinux_netlbl_socket_post_create - Label a socket using NetLabel
* @sk: the sock to label
* @family: protocol family
*
* Description:
* Attempt to label a socket using the NetLabel mechanism using the given
* SID. Returns zero values on success, negative values on failure.
*
*/
int selinux_netlbl_socket_post_create(struct sock *sk, u16 family)
{
int rc;
struct sk_security_struct *sksec = selinux_sock(sk);
struct netlbl_lsm_secattr *secattr;
if (family != PF_INET && family != PF_INET6)
return 0;
secattr = selinux_netlbl_sock_genattr(sk);
if (IS_ERR(secattr))
return PTR_ERR(secattr);
/* On socket creation, replacement of IP options is safe even if
* the caller does not hold the socket lock.
*/
rc = netlbl_sock_setattr(sk, family, secattr, true);
switch (rc) {
case 0:
sksec->nlbl_state = NLBL_LABELED;
break;
case -EDESTADDRREQ:
sksec->nlbl_state = NLBL_REQSKB;
rc = 0;
break;
}
return rc;
}
/**
* selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
* @sksec: the sock's sk_security_struct
* @skb: the packet
* @family: protocol family
* @ad: the audit data
*
* Description:
* Fetch the NetLabel security attributes from @skb and perform an access check
* against the receiving socket. Returns zero on success, negative values on
* error.
*
*/
int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
struct sk_buff *skb,
u16 family,
struct common_audit_data *ad)
{
int rc;
u32 nlbl_sid;
u32 perm;
struct netlbl_lsm_secattr secattr;
if (!netlbl_enabled())
return 0;
netlbl_secattr_init(&secattr);
rc = netlbl_skbuff_getattr(skb, family, &secattr);
if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
rc = selinux_netlbl_sidlookup_cached(skb, family,
&secattr, &nlbl_sid);
else
nlbl_sid = SECINITSID_UNLABELED;
netlbl_secattr_destroy(&secattr);
if (rc != 0)
return rc;
switch (sksec->sclass) {
case SECCLASS_UDP_SOCKET:
perm = UDP_SOCKET__RECVFROM;
break;
case SECCLASS_TCP_SOCKET:
perm = TCP_SOCKET__RECVFROM;
break;
default:
perm = RAWIP_SOCKET__RECVFROM;
}
rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
if (rc == 0)
return 0;
if (nlbl_sid != SECINITSID_UNLABELED)
netlbl_skbuff_err(skb, family, rc, 0);
return rc;
}
/**
* selinux_netlbl_option - Is this a NetLabel option
* @level: the socket level or protocol
* @optname: the socket option name
*
* Description:
* Returns true if @level and @optname refer to a NetLabel option.
* Helper for selinux_netlbl_socket_setsockopt().
*/
static inline int selinux_netlbl_option(int level, int optname)
{
return (level == IPPROTO_IP && optname == IP_OPTIONS) ||
(level == IPPROTO_IPV6 && optname == IPV6_HOPOPTS);
}
/**
* selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
* @sock: the socket
* @level: the socket level or protocol
* @optname: the socket option name
*
* Description:
* Check the setsockopt() call and if the user is trying to replace the IP
* options on a socket and a NetLabel is in place for the socket deny the
* access; otherwise allow the access. Returns zero when the access is
* allowed, -EACCES when denied, and other negative values on error.
*
*/
int selinux_netlbl_socket_setsockopt(struct socket *sock,
int level,
int optname)
{
int rc = 0;
struct sock *sk = sock->sk;
struct sk_security_struct *sksec = selinux_sock(sk);
struct netlbl_lsm_secattr secattr;
if (selinux_netlbl_option(level, optname) &&
(sksec->nlbl_state == NLBL_LABELED ||
sksec->nlbl_state == NLBL_CONNLABELED)) {
netlbl_secattr_init(&secattr);
lock_sock(sk);
/* call the netlabel function directly as we want to see the
* on-the-wire label that is assigned via the socket's options
* and not the cached netlabel/lsm attributes */
rc = netlbl_sock_getattr(sk, &secattr);
release_sock(sk);
if (rc == 0)
rc = -EACCES;
else if (rc == -ENOMSG)
rc = 0;
netlbl_secattr_destroy(&secattr);
}
return rc;
}
/**
* selinux_netlbl_socket_connect_helper - Help label a client-side socket on
* connect
* @sk: the socket to label
* @addr: the destination address
*
* Description:
* Attempt to label a connected socket with NetLabel using the given address.
* Returns zero values on success, negative values on failure.
*
*/
static int selinux_netlbl_socket_connect_helper(struct sock *sk,
struct sockaddr *addr)
{
int rc;
struct sk_security_struct *sksec = selinux_sock(sk);
struct netlbl_lsm_secattr *secattr;
/* connected sockets are allowed to disconnect when the address family
* is set to AF_UNSPEC, if that is what is happening we want to reset
* the socket */
if (addr->sa_family == AF_UNSPEC) {
netlbl_sock_delattr(sk);
sksec->nlbl_state = NLBL_REQSKB;
rc = 0;
return rc;
}
secattr = selinux_netlbl_sock_genattr(sk);
if (IS_ERR(secattr))
return PTR_ERR(secattr);
rc = netlbl_conn_setattr(sk, addr, secattr);
if (rc == 0)
sksec->nlbl_state = NLBL_CONNLABELED;
return rc;
}
/**
* selinux_netlbl_socket_connect_locked - Label a client-side socket on
* connect
* @sk: the socket to label
* @addr: the destination address
*
* Description:
* Attempt to label a connected socket that already has the socket locked
* with NetLabel using the given address.
* Returns zero values on success, negative values on failure.
*
*/
int selinux_netlbl_socket_connect_locked(struct sock *sk,
struct sockaddr *addr)
{
struct sk_security_struct *sksec = selinux_sock(sk);
if (sksec->nlbl_state != NLBL_REQSKB &&
sksec->nlbl_state != NLBL_CONNLABELED)
return 0;
return selinux_netlbl_socket_connect_helper(sk, addr);
}
/**
* selinux_netlbl_socket_connect - Label a client-side socket on connect
* @sk: the socket to label
* @addr: the destination address
*
* Description:
* Attempt to label a connected socket with NetLabel using the given address.
* Returns zero values on success, negative values on failure.
*
*/
int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr)
{
int rc;
lock_sock(sk);
rc = selinux_netlbl_socket_connect_locked(sk, addr);
release_sock(sk);
return rc;
}
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