1 /*
2 * Copyright (c) 2023 Apple Computer, 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
29 #include <darwintest.h>
30 #include <stdlib.h>
31 #include <unistd.h>
32 #include <mach/exception_types.h>
33 #include <sys/wait.h>
34
35 #include "exc_helpers.h"
36 #include "test_utils.h"
37
38 T_GLOBAL_META(
39 T_META_NAMESPACE("xnu.arm"),
40 T_META_RADAR_COMPONENT_NAME("xnu"),
41 T_META_RADAR_COMPONENT_VERSION("arm"),
42 T_META_OWNER("ghackmann"),
43 T_META_REQUIRES_SYSCTL_EQ("hw.optional.ptrauth", 1),
44 T_META_IGNORECRASHES(".*pac_exception_entitlement.*"),
45 XNU_T_META_SOC_SPECIFIC
46 );
47
48 #if __arm64e__
49 static size_t
exception_handler(mach_port_t task __unused,mach_port_t thread __unused,exception_type_t type __unused,mach_exception_data_t codes __unused)50 exception_handler(mach_port_t task __unused, mach_port_t thread __unused,
51 exception_type_t type __unused, mach_exception_data_t codes __unused)
52 {
53 T_ASSERT_FAIL("kernel ran exception handler instead of terminating process");
54 }
55
56 /*
57 * Real-world software should use ptrauth.h when it needs to manually sign or
58 * auth pointers. But for testing purposes we need clang to emit specific
59 * ptrauth instructions, so we use inline asm here instead.
60 *
61 * Likewise clang would normally combine the "naked" auth and brk testcases as
62 * part of a sequence like:
63 *
64 * output = auth(...);
65 * if (output is poisoned) {
66 * brk(PTRAUTH_FAILURE_COMMENT);
67 * }
68 *
69 * On auth failure, CPUs that implement FEAT_FPAC will trap immediately at the
70 * auth instruction, and CPUs without FEAT_FPAC will trap at the later brk
71 * instruction. But again, for testing purposes we want these to be two
72 * discrete cases. (On FPAC-enabled CPUs, the kernel should treat *both* traps
73 * as ptrauth failure, even if we don't expect the latter to be reachable in
74 * real-world software.)
75 */
76
77 static void
naked_auth(void)78 naked_auth(void)
79 {
80 asm volatile (
81 "mov x0, #0" "\n"
82 "paciza x0" "\n"
83 "eor x0, x0, (1 << 63)" "\n"
84 "autiza x0"
85 :
86 :
87 : "x0"
88 );
89 }
90
91 static void
ptrauth_brk(void)92 ptrauth_brk(void)
93 {
94 asm volatile ("brk 0xc470");
95 }
96
97 static void
combined_branch_auth(void)98 combined_branch_auth(void)
99 {
100 asm volatile (
101 "adr x0, 1f" "\n"
102 "paciza x0" "\n"
103 "eor x0, x0, (1 << 63)" "\n"
104 "braaz x0" "\n"
105 "1:"
106 :
107 :
108 : "x0"
109 );
110 }
111
112 static void
combined_load_auth(void)113 combined_load_auth(void)
114 {
115 asm volatile (
116 "mov x0, sp" "\n"
117 "pacdza x0" "\n"
118 "eor x0, x0, (1 << 63)" "\n"
119 "ldraa x0, [x0]" "\n"
120 :
121 :
122 : "x0"
123 );
124 }
125
126 static void
run_pac_exception_test(void (* ptrauth_failure_fn)(void))127 run_pac_exception_test(void (*ptrauth_failure_fn)(void))
128 {
129 pid_t pid = fork();
130 T_QUIET; T_ASSERT_POSIX_SUCCESS(pid, "fork");
131
132 if (pid == 0) {
133 mach_port_t exc_port = create_exception_port(EXC_MASK_BAD_ACCESS | EXC_MASK_BREAKPOINT);
134 run_exception_handler(exc_port, exception_handler);
135
136 ptrauth_failure_fn();
137 /* ptrauth_failure_fn() should have raised an uncatchable exception */
138 T_FAIL("child ran to completion");
139 } else {
140 int status;
141 int err = waitpid(pid, &status, 0);
142 T_QUIET; T_ASSERT_POSIX_SUCCESS(err, "waitpid");
143
144 T_EXPECT_TRUE(WIFSIGNALED(status), "child terminated due to signal");
145 T_EXPECT_EQ(SIGKILL, WTERMSIG(status), "child terminated due to SIGKILL");
146 }
147 }
148 #endif
149
150 T_DECL(pac_exception_naked_auth,
151 "Test the com.apple.private.pac.exception entitlement (naked auth failure)",
152 T_META_REQUIRES_SYSCTL_EQ("hw.optional.arm.FEAT_FPAC", 1))
153 {
154 #if __arm64e__
155 run_pac_exception_test(naked_auth);
156 #else
157 T_SKIP("Running on non-arm64e target, skipping...");
158 #endif
159 }
160
161
162 T_DECL(pac_exception_ptrauth_brk,
163 "Test the com.apple.private.pac.exception entitlement (brk with comment indicating ptrauth failure)")
164 {
165 #if __arm64e__
166 run_pac_exception_test(ptrauth_brk);
167 #else
168 T_SKIP("Running on non-arm64e target, skipping...");
169 #endif
170 }
171
172 T_DECL(pac_exception_combined_branch_auth,
173 "Test the com.apple.private.pac.exception entitlement (combined branch + auth failure)")
174 {
175 #if __arm64e__
176 run_pac_exception_test(combined_branch_auth);
177 #else
178 T_SKIP("Running on non-arm64e target, skipping...");
179 #endif
180 }
181
182 T_DECL(pac_exception_combined_load_auth,
183 "Test the com.apple.private.pac.exception entitlement (combined branch + auth failure)")
184 {
185 #if __arm64e__
186 run_pac_exception_test(combined_load_auth);
187 #else
188 T_SKIP("Running on non-arm64e target, skipping...");
189 #endif
190 }
191