FreeBSD/Linux Kernel Cross Reference
sys/security/mac/mac_socket.c

     /*-
      * Copyright (c) 1999-2002, 2009 Robert N. M. Watson
      * Copyright (c) 2001 Ilmar S. Habibulin
      * Copyright (c) 2001-2005 Networks Associates Technology, Inc.
      * Copyright (c) 2005-2006 SPARTA, Inc.
      * Copyright (c) 2008 Apple Inc.
      * All rights reserved.
      *
      * This software was developed by Robert Watson and Ilmar Habibulin for the
     * TrustedBSD Project.
     *
     * This software was developed for the FreeBSD Project in part by McAfee
     * Research, the Technology Research Division of Network Associates, Inc.
     * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
     * DARPA CHATS research program.
     *
     * This software was enhanced by SPARTA ISSO under SPAWAR contract
     * N66001-04-C-6019 ("SEFOS").
     *
     * This software was developed at the University of Cambridge Computer
     * Laboratory with support from a grant from Google, Inc.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/11.0/sys/security/mac/mac_socket.c 258541 2013-11-25 07:38:45Z attilio $");
    
    #include "opt_mac.h"
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mutex.h>
    #include <sys/mac.h>
    #include <sys/sbuf.h>
    #include <sys/sdt.h>
    #include <sys/systm.h>
    #include <sys/mount.h>
    #include <sys/file.h>
    #include <sys/namei.h>
    #include <sys/protosw.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/sysctl.h>
    
    #include <net/bpfdesc.h>
    #include <net/if.h>
    #include <net/if_var.h>
    
    #include <netinet/in.h>
    #include <netinet/in_pcb.h>
    #include <netinet/ip_var.h>
    
    #include <security/mac/mac_framework.h>
    #include <security/mac/mac_internal.h>
    #include <security/mac/mac_policy.h>
    
    /*
     * Currently, sockets hold two labels: the label of the socket itself, and a
     * peer label, which may be used by policies to hold a copy of the label of
     * any remote endpoint.
     *
     * Possibly, this peer label should be maintained at the protocol layer
     * (inpcb, unpcb, etc), as this would allow protocol-aware code to maintain
     * the label consistently.  For example, it might be copied live from a
     * remote socket for UNIX domain sockets rather than keeping a local copy on
     * this endpoint, but be cached and updated based on packets received for
     * TCP/IP.
     *
     * Unlike with many other object types, the lock protecting MAC labels on
     * sockets (the socket lock) is not frequently held at the points in code
     * where socket-related checks are called.  The MAC Framework acquires the
     * lock over some entry points in order to enforce atomicity (such as label
     * copies) but in other cases the policy modules will have to acquire the
     * lock themselves if they use labels.  This approach (a) avoids lock
     * acquisitions when policies don't require labels and (b) solves a number of
     * potential lock order issues when multiple sockets are used in the same
     * entry point.
    */
   
   struct label *
   mac_socket_label_alloc(int flag)
   {
           struct label *label;
           int error;
   
           label = mac_labelzone_alloc(flag);
           if (label == NULL)
                   return (NULL);
   
           if (flag & M_WAITOK)
                   MAC_POLICY_CHECK(socket_init_label, label, flag);
           else
                   MAC_POLICY_CHECK_NOSLEEP(socket_init_label, label, flag);
           if (error) {
                   MAC_POLICY_PERFORM_NOSLEEP(socket_destroy_label, label);
                   mac_labelzone_free(label);
                   return (NULL);
           }
           return (label);
   }
   
   static struct label *
   mac_socketpeer_label_alloc(int flag)
   {
           struct label *label;
           int error;
   
           label = mac_labelzone_alloc(flag);
           if (label == NULL)
                   return (NULL);
   
           if (flag & M_WAITOK)
                   MAC_POLICY_CHECK(socketpeer_init_label, label, flag);
           else
                   MAC_POLICY_CHECK_NOSLEEP(socketpeer_init_label, label, flag);
           if (error) {
                   MAC_POLICY_PERFORM_NOSLEEP(socketpeer_destroy_label, label);
                   mac_labelzone_free(label);
                   return (NULL);
           }
           return (label);
   }
   
   int
   mac_socket_init(struct socket *so, int flag)
   {
   
           if (mac_labeled & MPC_OBJECT_SOCKET) {
                   so->so_label = mac_socket_label_alloc(flag);
                   if (so->so_label == NULL)
                           return (ENOMEM);
                   so->so_peerlabel = mac_socketpeer_label_alloc(flag);
                   if (so->so_peerlabel == NULL) {
                           mac_socket_label_free(so->so_label);
                           so->so_label = NULL;
                           return (ENOMEM);
                   }
           } else {
                   so->so_label = NULL;
                   so->so_peerlabel = NULL;
           }
           return (0);
   }
   
   void
   mac_socket_label_free(struct label *label)
   {
   
           MAC_POLICY_PERFORM_NOSLEEP(socket_destroy_label, label);
           mac_labelzone_free(label);
   }
   
   static void
   mac_socketpeer_label_free(struct label *label)
   {
   
           MAC_POLICY_PERFORM_NOSLEEP(socketpeer_destroy_label, label);
           mac_labelzone_free(label);
   }
   
   void
   mac_socket_destroy(struct socket *so)
   {
   
           if (so->so_label != NULL) {
                   mac_socket_label_free(so->so_label);
                   so->so_label = NULL;
                   mac_socketpeer_label_free(so->so_peerlabel);
                   so->so_peerlabel = NULL;
           }
   }
   
   void
   mac_socket_copy_label(struct label *src, struct label *dest)
   {
   
           MAC_POLICY_PERFORM_NOSLEEP(socket_copy_label, src, dest);
   }
   
   int
   mac_socket_externalize_label(struct label *label, char *elements,
       char *outbuf, size_t outbuflen)
   {
           int error;
   
           MAC_POLICY_EXTERNALIZE(socket, label, elements, outbuf, outbuflen);
   
           return (error);
   }
   
   static int
   mac_socketpeer_externalize_label(struct label *label, char *elements,
       char *outbuf, size_t outbuflen)
   {
           int error;
   
           MAC_POLICY_EXTERNALIZE(socketpeer, label, elements, outbuf,
               outbuflen);
   
           return (error);
   }
   
   int
   mac_socket_internalize_label(struct label *label, char *string)
   {
           int error;
   
           MAC_POLICY_INTERNALIZE(socket, label, string);
   
           return (error);
   }
   
   void
   mac_socket_create(struct ucred *cred, struct socket *so)
   {
   
           MAC_POLICY_PERFORM_NOSLEEP(socket_create, cred, so, so->so_label);
   }
   
   void
   mac_socket_newconn(struct socket *oldso, struct socket *newso)
   {
   
           MAC_POLICY_PERFORM_NOSLEEP(socket_newconn, oldso, oldso->so_label,
               newso, newso->so_label);
   }
   
   static void
   mac_socket_relabel(struct ucred *cred, struct socket *so,
       struct label *newlabel)
   {
   
           SOCK_LOCK_ASSERT(so);
   
           MAC_POLICY_PERFORM_NOSLEEP(socket_relabel, cred, so, so->so_label,
               newlabel);
   }
   
   void
   mac_socketpeer_set_from_mbuf(struct mbuf *m, struct socket *so)
   {
           struct label *label;
   
           if (mac_policy_count == 0)
                   return;
   
           label = mac_mbuf_to_label(m);
   
           MAC_POLICY_PERFORM_NOSLEEP(socketpeer_set_from_mbuf, m, label, so,
               so->so_peerlabel);
   }
   
   void
   mac_socketpeer_set_from_socket(struct socket *oldso, struct socket *newso)
   {
           
           if (mac_policy_count == 0)
                   return;
   
           MAC_POLICY_PERFORM_NOSLEEP(socketpeer_set_from_socket, oldso,
               oldso->so_label, newso, newso->so_peerlabel);
   }
   
   void
   mac_socket_create_mbuf(struct socket *so, struct mbuf *m)
   {
           struct label *label;
   
           if (mac_policy_count == 0)
                   return;
   
           label = mac_mbuf_to_label(m);
   
           MAC_POLICY_PERFORM_NOSLEEP(socket_create_mbuf, so, so->so_label, m,
               label);
   }
   
   MAC_CHECK_PROBE_DEFINE2(socket_check_accept, "struct ucred *",
       "struct socket *");
   
   int
   mac_socket_check_accept(struct ucred *cred, struct socket *so)
   {
           int error;
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_accept, cred, so,
               so->so_label);
           MAC_CHECK_PROBE2(socket_check_accept, error, cred, so);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE3(socket_check_bind, "struct ucred *",
       "struct socket *", "struct sockaddr *");
   
   int
   mac_socket_check_bind(struct ucred *cred, struct socket *so,
       struct sockaddr *sa)
   {
           int error;
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_bind, cred, so, so->so_label,
               sa);
           MAC_CHECK_PROBE3(socket_check_bind, error, cred, so, sa);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE3(socket_check_connect, "struct ucred *",
       "struct socket *", "struct sockaddr *");
   
   int
   mac_socket_check_connect(struct ucred *cred, struct socket *so,
       struct sockaddr *sa)
   {
           int error;
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_connect, cred, so,
               so->so_label, sa);
           MAC_CHECK_PROBE3(socket_check_connect, error, cred, so, sa);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE4(socket_check_create, "struct ucred *", "int", "int",
       "int");
   
   int
   mac_socket_check_create(struct ucred *cred, int domain, int type, int proto)
   {
           int error;
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_create, cred, domain, type,
               proto);
           MAC_CHECK_PROBE4(socket_check_create, error, cred, domain, type,
               proto);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE2(socket_check_deliver, "struct socket *",
       "struct mbuf *");
   
   int
   mac_socket_check_deliver(struct socket *so, struct mbuf *m)
   {
           struct label *label;
           int error;
   
           if (mac_policy_count == 0)
                   return (0);
   
           label = mac_mbuf_to_label(m);
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_deliver, so, so->so_label, m,
               label);
           MAC_CHECK_PROBE2(socket_check_deliver, error, so, m);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE2(socket_check_listen, "struct ucred *",
       "struct socket *");
   
   int
   mac_socket_check_listen(struct ucred *cred, struct socket *so)
   {
           int error;
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_listen, cred, so,
               so->so_label);
           MAC_CHECK_PROBE2(socket_check_listen, error, cred, so);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE2(socket_check_poll, "struct ucred *",
       "struct socket *");
   
   int
   mac_socket_check_poll(struct ucred *cred, struct socket *so)
   {
           int error;
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_poll, cred, so, so->so_label);
           MAC_CHECK_PROBE2(socket_check_poll, error, cred, so);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE2(socket_check_receive, "struct ucred *",
       "struct socket *");
   
   int
   mac_socket_check_receive(struct ucred *cred, struct socket *so)
   {
           int error;
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_receive, cred, so,
               so->so_label);
           MAC_CHECK_PROBE2(socket_check_receive, error, cred, so);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE3(socket_check_relabel, "struct ucred *",
       "struct socket *", "struct label *");
   
   static int
   mac_socket_check_relabel(struct ucred *cred, struct socket *so,
       struct label *newlabel)
   {
           int error;
   
           SOCK_LOCK_ASSERT(so);
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_relabel, cred, so,
               so->so_label, newlabel);
           MAC_CHECK_PROBE3(socket_check_relabel, error, cred, so, newlabel);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE2(socket_check_send, "struct ucred *",
       "struct socket *");
   
   int
   mac_socket_check_send(struct ucred *cred, struct socket *so)
   {
           int error;
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_send, cred, so, so->so_label);
           MAC_CHECK_PROBE2(socket_check_send, error, cred, so);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE2(socket_check_stat, "struct ucred *",
       "struct socket *");
   
   int
   mac_socket_check_stat(struct ucred *cred, struct socket *so)
   {
           int error;
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_stat, cred, so, so->so_label);
           MAC_CHECK_PROBE2(socket_check_stat, error, cred, so);
   
           return (error);
   }
   
   MAC_CHECK_PROBE_DEFINE2(socket_check_visible, "struct ucred *",
       "struct socket *");
   
   int
   mac_socket_check_visible(struct ucred *cred, struct socket *so)
   {
           int error;
   
           MAC_POLICY_CHECK_NOSLEEP(socket_check_visible, cred, so,
               so->so_label);
           MAC_CHECK_PROBE2(socket_check_visible, error, cred, so);
   
           return (error);
   }
   
   int
   mac_socket_label_set(struct ucred *cred, struct socket *so,
       struct label *label)
   {
           int error;
   
           /*
            * We acquire the socket lock when we perform the test and set, but
            * have to release it as the pcb code needs to acquire the pcb lock,
            * which will precede the socket lock in the lock order.  However,
            * this is fine, as any race will simply result in the inpcb being
            * refreshed twice, but still consistently, as the inpcb code will
            * acquire the socket lock before refreshing, holding both locks.
            */
           SOCK_LOCK(so);
           error = mac_socket_check_relabel(cred, so, label);
           if (error) {
                   SOCK_UNLOCK(so);
                   return (error);
           }
   
           mac_socket_relabel(cred, so, label);
           SOCK_UNLOCK(so);
   
           /*
            * If the protocol has expressed interest in socket layer changes,
            * such as if it needs to propagate changes to a cached pcb label
            * from the socket, notify it of the label change while holding the
            * socket lock.
            */
           if (so->so_proto->pr_usrreqs->pru_sosetlabel != NULL)
                   (so->so_proto->pr_usrreqs->pru_sosetlabel)(so);
   
           return (0);
   }
   
   int
   mac_setsockopt_label(struct ucred *cred, struct socket *so, struct mac *mac)
   {
           struct label *intlabel;
           char *buffer;
           int error;
   
           if (!(mac_labeled & MPC_OBJECT_SOCKET))
                   return (EINVAL);
   
           error = mac_check_structmac_consistent(mac);
           if (error)
                   return (error);
   
           buffer = malloc(mac->m_buflen, M_MACTEMP, M_WAITOK);
           error = copyinstr(mac->m_string, buffer, mac->m_buflen, NULL);
           if (error) {
                   free(buffer, M_MACTEMP);
                   return (error);
           }
   
           intlabel = mac_socket_label_alloc(M_WAITOK);
           error = mac_socket_internalize_label(intlabel, buffer);
           free(buffer, M_MACTEMP);
           if (error)
                   goto out;
   
           error = mac_socket_label_set(cred, so, intlabel);
   out:
           mac_socket_label_free(intlabel);
           return (error);
   }
   
   int
   mac_getsockopt_label(struct ucred *cred, struct socket *so, struct mac *mac)
   {
           char *buffer, *elements;
           struct label *intlabel;
           int error;
   
           if (!(mac_labeled & MPC_OBJECT_SOCKET))
                   return (EINVAL);
   
           error = mac_check_structmac_consistent(mac);
           if (error)
                   return (error);
   
           elements = malloc(mac->m_buflen, M_MACTEMP, M_WAITOK);
           error = copyinstr(mac->m_string, elements, mac->m_buflen, NULL);
           if (error) {
                   free(elements, M_MACTEMP);
                   return (error);
           }
   
           buffer = malloc(mac->m_buflen, M_MACTEMP, M_WAITOK | M_ZERO);
           intlabel = mac_socket_label_alloc(M_WAITOK);
           SOCK_LOCK(so);
           mac_socket_copy_label(so->so_label, intlabel);
           SOCK_UNLOCK(so);
           error = mac_socket_externalize_label(intlabel, elements, buffer,
               mac->m_buflen);
           mac_socket_label_free(intlabel);
           if (error == 0)
                   error = copyout(buffer, mac->m_string, strlen(buffer)+1);
   
           free(buffer, M_MACTEMP);
           free(elements, M_MACTEMP);
   
           return (error);
   }
   
   int
   mac_getsockopt_peerlabel(struct ucred *cred, struct socket *so,
       struct mac *mac)
   {
           char *elements, *buffer;
           struct label *intlabel;
           int error;
   
           if (!(mac_labeled & MPC_OBJECT_SOCKET))
                   return (EINVAL);
   
           error = mac_check_structmac_consistent(mac);
           if (error)
                   return (error);
   
           elements = malloc(mac->m_buflen, M_MACTEMP, M_WAITOK);
           error = copyinstr(mac->m_string, elements, mac->m_buflen, NULL);
           if (error) {
                   free(elements, M_MACTEMP);
                   return (error);
           }
   
           buffer = malloc(mac->m_buflen, M_MACTEMP, M_WAITOK | M_ZERO);
           intlabel = mac_socket_label_alloc(M_WAITOK);
           SOCK_LOCK(so);
           mac_socket_copy_label(so->so_peerlabel, intlabel);
           SOCK_UNLOCK(so);
           error = mac_socketpeer_externalize_label(intlabel, elements, buffer,
               mac->m_buflen);
           mac_socket_label_free(intlabel);
           if (error == 0)
                   error = copyout(buffer, mac->m_string, strlen(buffer)+1);
   
           free(buffer, M_MACTEMP);
           free(elements, M_MACTEMP);
   
           return (error);
   }

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