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 */
57ipc_port_t
58audit_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 ipc_kobject_set(new_port, (ipc_kobject_t)aia_p, IKOT_AU_SESSIONPORT);
72 if (!OSCompareAndSwapPtr(port, new_port, sessionport))
73 ipc_port_dealloc_kernel(new_port);
74 port = *sessionport;
75 }
76
77 assert(ip_active(port) && IKOT_AU_SESSIONPORT == ip_kotype(port));
78 sendport = ipc_port_make_send(port);
79
80 /*
81 * If we don't have a no-senders notification outstanding against
82 * the port, take a reference on the session and request one.
83 */
84 if (IP_NULL == port->ip_nsrequest) {
85 ipc_port_t notifyport;
86
87 audit_session_aiaref(aia_p);
88
89
90 ip_lock(port);
91 /* Need a send-once right for the target of the notification */
92 notifyport = ipc_port_make_sonce_locked(port);
93 /* Request a no-senders notification (at the new make-send threshold) */
94 ipc_port_nsrequest(port, port->ip_mscount, notifyport, &notifyport);
95 /* port unlocked */
96
97 if (IP_NULL != notifyport) {
98 /* race requesting notification */
99 audit_session_aiaunref(aia_p);
100 ipc_port_release_sonce(notifyport);
101 }
102 }
103
104 return (sendport);
105}
106
107
108/*
109 * audit_session_porttoaia
110 *
111 * Description: Obtain the audit session info associated with the given port.
112
113 * Parameters: port A Mach port.
114 *
115 * Returns: NULL The given Mach port did not reference audit
116 * session info.
117 * !NULL The audit session info that is associated with
118 * the Mach port.
119 *
120 * Notes: The caller must have a reference on the sessionport.
121 */
122struct auditinfo_addr *
123audit_session_porttoaia(ipc_port_t port)
124{
125 struct auditinfo_addr *aia_p = NULL;
126
127 if (IP_VALID(port)) {
128 ip_lock(port);
129 if (IKOT_AU_SESSIONPORT == ip_kotype(port)) {
130 assert(ip_active(port));
131 aia_p = (struct auditinfo_addr *)port->ip_kobject;
132 }
133 ip_unlock(port);
134 }
135
136 return (aia_p);
137}
138
139
140/*
141 * audit_session_nosenders
142 *
143 * Description: Handle a no-senders notification for a sessionport.
144 *
145 * Parameters: msg A Mach no-senders notification message.
146 *
147 * Notes: It is possible that new send rights are created after a
148 * no-senders notification has been sent (i.e. via audit_session_mksend).
149 * We check the port's mscount against the notification's not_count
150 * to detect when this happens, and re-arm the notification in that
151 * case.
152 *
153 * In the normal case (no new senders), we first mark the port
154 * as dying by setting its object type to IKOT_NONE so that
155 * audit_session_mksend will no longer use it to create
156 * additional send rights. We can then safely call
157 * audit_session_port_destroy with no locks.
158 */
159void
160audit_session_nosenders(mach_msg_header_t *msg)
161{
162 mach_no_senders_notification_t *notification = (void *)msg;
163 ipc_port_t port = notification->not_header.msgh_remote_port;
164 ipc_port_t notifyport;
165 struct auditinfo_addr *port_aia_p = NULL;
166
167 assert(IKOT_AU_SESSIONPORT == ip_kotype(port));
168 ip_lock(port);
169 assert(ip_active(port));
170 port_aia_p = (struct auditinfo_addr *)port->ip_kobject;
171 assert(NULL != port_aia_p);
172
173 /*
174 * if new send rights have been made since the last notify
175 * request, re-arm the notification with the new threshold.
176 */
177 if (port->ip_mscount > notification->not_count) {
178 notifyport = ipc_port_make_sonce_locked(port);
179 ipc_port_nsrequest(port, port->ip_mscount, notifyport, &notifyport);
180 /* port unlocked */
181
182 if (IP_NULL != notifyport) {
183 /* race re-arming the notification */
184 ipc_port_release_sonce(notifyport);
185 audit_session_aiaunref(port_aia_p);
186 }
187 return;
188 }
189
190 /*
191 * Otherwise, no more extant send rights, so release the
192 * reference held on the session by those send rights.
193 */
194 ip_unlock(port);
195 audit_session_aiaunref(port_aia_p);
196}
197
198void
199audit_session_portdestroy(ipc_port_t *sessionport)
200{
201 ipc_port_t port = *sessionport;
202
203 if (IP_VALID(port)) {
204 assert (ip_active(port));
205 assert(IKOT_AU_SESSIONPORT == ip_kotype(port));
206 ipc_kobject_set_atomically(port, IKO_NULL, IKOT_NONE);
207 ipc_port_dealloc_kernel(port);
208 *sessionport = IP_NULL;
209 }
210}
211#endif /* CONFIG_AUDIT */
212