osfmk/kern/audit_sessionport.c

   1 /*
   2  * Copyright (c) 2008 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 #include <mach/mach_types.h>
  29 #include <mach/notify.h>
  30 #include <ipc/ipc_port.h>
  31 #include <kern/ipc_kobject.h>
  32 #include <kern/audit_sessionport.h>
  33 #include <libkern/OSAtomic.h>
  34
  35 #if CONFIG_AUDIT
  36 /*
  37  * audit_session_mksend
  38  *
  39  * Description: Obtain a send right for given audit session.
  40  *
  41  * Parameters:  *aia_p          Audit session information to assosiate with
  42  *                              the new port.
  43  *              *sessionport    Pointer to the current session port.  This may
  44  *                              actually be set to IPC_PORT_NULL.
  45  *
  46  * Returns:     !NULL           Resulting send right.
  47  *              NULL            Failed to allocate port (due to lack of memory
  48  *                              resources).
  49  *
  50  * Assumptions: Caller holds a reference on the session during the call.
  51  *              If there were no outstanding send rights against the port,
  52  *              hold a reference on the session and arm a new no-senders
  53  *              notification to determine when to release that reference.
  54  *              Otherwise, by creating an additional send right, we share
  55  *              the port's reference until all send rights go away.
  56  */
  57 ipc_port_t
  58 audit_session_mksend(struct auditinfo_addr *aia_p, ipc_port_t *sessionport)
  59 {
  60         ipc_port_t sendport = IPC_PORT_NULL;
  61         ipc_port_t port;
  62
  63         /*
  64          * If we don't have an existing session port, then create one.
  65          */
  66         port = *sessionport;
  67         if (!IP_VALID(port)) {
  68                 ipc_port_t new_port = ipc_port_alloc_kernel();
  69                 if (!IP_VALID(new_port)) {
  70                         return new_port;
  71                 }
  72                 ipc_kobject_set(new_port, (ipc_kobject_t)aia_p, IKOT_AU_SESSIONPORT);
  73                 if (!OSCompareAndSwapPtr(port, new_port, sessionport)) {
  74                         ipc_port_dealloc_kernel(new_port);
  75                 }
  76                 port = *sessionport;
  77         }
  78
  79         assert(ip_active(port) && IKOT_AU_SESSIONPORT == ip_kotype(port));
  80         sendport = ipc_port_make_send(port);
  81
  82         /*
  83          * If we don't have a no-senders notification outstanding against
  84          * the port, take a reference on the session and request one.
  85          */
  86         if (IP_NULL == port->ip_nsrequest) {
  87                 ipc_port_t notifyport;
  88
  89                 audit_session_aiaref(aia_p);
  90
  91
  92                 ip_lock(port);
  93                 /* Need a send-once right for the target of the notification */
  94                 notifyport = ipc_port_make_sonce_locked(port);
  95                 /* Request a no-senders notification (at the new make-send threshold) */
  96                 ipc_port_nsrequest(port, port->ip_mscount, notifyport, &notifyport);
  97                 /* port unlocked */
  98
  99                 if (IP_NULL != notifyport) {
 100                         /* race requesting notification */
 101                         audit_session_aiaunref(aia_p);
 102                         ipc_port_release_sonce(notifyport);
 103                 }
 104         }
 105
 106         return sendport;
 107 }
 108
 109
 110 /*
 111  * audit_session_porttoaia
 112  *
 113  * Description: Obtain the audit session info associated with the given port.
 114  *
 115  * Parameters: port             A Mach port.
 116  *
 117  * Returns:    NULL             The given Mach port did not reference audit
 118  *                              session info.
 119  *             !NULL            The audit session info that is associated with
 120  *                              the Mach port.
 121  *
 122  * Notes: The caller must have a reference on the sessionport.
 123  */
 124 struct auditinfo_addr *
 125 audit_session_porttoaia(ipc_port_t port)
 126 {
 127         struct auditinfo_addr *aia_p = NULL;
 128
 129         if (IP_VALID(port)) {
 130                 ip_lock(port);
 131                 if (IKOT_AU_SESSIONPORT == ip_kotype(port)) {
 132                         assert(ip_active(port));
 133                         aia_p = (struct auditinfo_addr *)port->ip_kobject;
 134                 }
 135                 ip_unlock(port);
 136         }
 137
 138         return aia_p;
 139 }
 140
 141
 142 /*
 143  * audit_session_nosenders
 144  *
 145  * Description: Handle a no-senders notification for a sessionport.
 146  *
 147  * Parameters: msg              A Mach no-senders notification message.
 148  *
 149  * Notes: It is possible that new send rights are created after a
 150  *        no-senders notification has been sent (i.e. via audit_session_mksend).
 151  *        We check the port's mscount against the notification's not_count
 152  *        to detect when this happens, and re-arm the notification in that
 153  *        case.
 154  *
 155  *        In the normal case (no new senders), we first mark the port
 156  *        as dying by setting its object type to IKOT_NONE so that
 157  *        audit_session_mksend will no longer use it to create
 158  *        additional send rights.  We can then safely call
 159  *        audit_session_port_destroy with no locks.
 160  */
 161 void
 162 audit_session_nosenders(mach_msg_header_t *msg)
 163 {
 164         mach_no_senders_notification_t *notification = (void *)msg;
 165         ipc_port_t port = notification->not_header.msgh_remote_port;
 166         ipc_port_t notifyport;
 167         struct auditinfo_addr *port_aia_p = NULL;
 168
 169         assert(IKOT_AU_SESSIONPORT == ip_kotype(port));
 170         ip_lock(port);
 171         assert(ip_active(port));
 172         port_aia_p = (struct auditinfo_addr *)port->ip_kobject;
 173         assert(NULL != port_aia_p);
 174
 175         /*
 176          * if new send rights have been made since the last notify
 177          * request, re-arm the notification with the new threshold.
 178          */
 179         if (port->ip_mscount > notification->not_count) {
 180                 notifyport = ipc_port_make_sonce_locked(port);
 181                 ipc_port_nsrequest(port, port->ip_mscount, notifyport, &notifyport);
 182                 /* port unlocked */
 183
 184                 if (IP_NULL != notifyport) {
 185                         /* race re-arming the notification */
 186                         ipc_port_release_sonce(notifyport);
 187                         audit_session_aiaunref(port_aia_p);
 188                 }
 189                 return;
 190         }
 191
 192         /*
 193          * Otherwise, no more extant send rights, so release the
 194          * reference held on the session by those send rights.
 195          */
 196         ip_unlock(port);
 197         audit_session_aiaunref(port_aia_p);
 198 }
 199
 200 void
 201 audit_session_portdestroy(ipc_port_t *sessionport)
 202 {
 203         ipc_port_t port = *sessionport;
 204
 205         if (IP_VALID(port)) {
 206                 assert(ip_active(port));
 207                 assert(IKOT_AU_SESSIONPORT == ip_kotype(port));
 208                 ipc_kobject_set_atomically(port, IKO_NULL, IKOT_NONE);
 209                 ipc_port_dealloc_kernel(port);
 210                 *sessionport = IP_NULL;
 211         }
 212 }
 213 #endif /* CONFIG_AUDIT */