/*
 * SELinux NetLabel Support
 *
 * This file provides the necessary glue to tie NetLabel into the SELinux
 * subsystem.
 *
 * Author: Paul Moore <paul@paul-moore.com>
 *
 */

/*
 * (c) Copyright Hewlett-Packard Development Company, L.P., 2007, 2008
 *
 * This program is free software;  you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY;  without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 * the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/gfp.h>
#include <linux/ip.h>
#include <linux/ipv6.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
 * @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(&selinux_state, 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, NULL on failure.
 *
 */
static struct netlbl_lsm_secattr *selinux_netlbl_sock_genattr(struct sock *sk)
{
        int rc;
        struct sk_security_struct *sksec = sk->sk_security;
        struct netlbl_lsm_secattr *secattr;

        if (sksec->nlbl_secattr != NULL)
                return sksec->nlbl_secattr;

        secattr = netlbl_secattr_alloc(GFP_ATOMIC);
        if (secattr == NULL)
                return NULL;
        rc = security_netlbl_sid_to_secattr(&selinux_state, sksec->sid,
                                            secattr);
        if (rc != 0) {
                netlbl_secattr_free(secattr);
                return NULL;
        }
        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 = sk->sk_security;
        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
 * @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 != NULL)
                netlbl_secattr_free(sksec->nlbl_secattr);
}

/**
 * selinux_netlbl_sk_security_reset - Reset the NetLabel fields
 * @sksec: the sk_security_struct
 * @family: the socket family
 *
 * 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()) {
                *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 = sk->sk_security;

                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(&selinux_state, 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.
 * @ep: incoming association endpoint.
 * @skb: the packet.
 *
 * Description:
 * A new incoming connection is represented by @ep, ......
 * Returns zero on success, negative values on failure.
 *
 */
int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep,
                                     struct sk_buff *skb)
{
        int rc;
        struct netlbl_lsm_secattr secattr;
        struct sk_security_struct *sksec = ep->base.sk->sk_security;
        struct sockaddr *addr;
        struct sockaddr_in addr4;
#if IS_ENABLED(CONFIG_IPV6)
        struct sockaddr_in6 addr6;
#endif

        if (ep->base.sk->sk_family != PF_INET &&
                                ep->base.sk->sk_family != PF_INET6)
                return 0;

        netlbl_secattr_init(&secattr);
        rc = security_netlbl_sid_to_secattr(&selinux_state,
                                            ep->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;
                addr = (struct sockaddr *)&addr4;
#if IS_ENABLED(CONFIG_IPV6)
        } else {
                addr6.sin6_family = AF_INET6;
                addr6.sin6_addr = ipv6_hdr(skb)->saddr;
                addr = (struct sockaddr *)&addr6;
#endif
        }

        rc = netlbl_conn_setattr(ep->base.sk, addr, &secattr);
        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
 *
 * 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(&selinux_state, 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
 *
 * 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 = sk->sk_security;

        if (family == PF_INET)
                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 = sk->sk_security;
        struct sk_security_struct *newsksec = newsk->sk_security;

        newsksec->nlbl_state = sksec->nlbl_state;
}

/**
 * selinux_netlbl_socket_post_create - Label a socket using NetLabel
 * @sock: the socket 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 = sk->sk_security;
        struct netlbl_lsm_secattr *secattr;

        if (family != PF_INET && family != PF_INET6)
                return 0;

        secattr = selinux_netlbl_sock_genattr(sk);
        if (secattr == NULL)
                return -ENOMEM;
        rc = netlbl_sock_setattr(sk, family, secattr);
        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(&selinux_state,
                          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 = sk->sk_security;
        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 = sk->sk_security;
        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 (secattr == NULL) {
                rc = -ENOMEM;
                return rc;
        }
        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 = sk->sk_security;

        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;
}