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 #include <sys/sysctl.h>
35 #include <sys/code_signing.h>
36
37 #include "exc_helpers.h"
38 #include "test_utils.h"
39
40 T_GLOBAL_META(
41 T_META_NAMESPACE("xnu.arm"),
42 T_META_RADAR_COMPONENT_NAME("xnu"),
43 T_META_RADAR_COMPONENT_VERSION("arm"),
44 T_META_OWNER("ghackmann"),
45 T_META_REQUIRES_SYSCTL_EQ("hw.optional.ptrauth", 1),
46 T_META_IGNORECRASHES(".*pac_exception_entitlement.*"),
47 XNU_T_META_SOC_SPECIFIC
48 );
49
50 #if __arm64e__
51 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)52 exception_handler(mach_port_t task __unused, mach_port_t thread __unused,
53 exception_type_t type __unused, mach_exception_data_t codes __unused)
54 {
55 T_ASSERT_FAIL("kernel ran exception handler instead of terminating process");
56 }
57
58 /*
59 * To trigger PAC failure, we create a validly-signed pointer and then flip an
60 * arbitrary PAC bit before accessing it. The exact number and location of PAC
61 * bits depends on the device configuration. For instruction pointers, the PAC
62 * field always includes bit 63. For data pointers, it may start as low as bit
63 * 54: bits 63-56 can be carved out for software tagging, and bit 55 is always
64 * reserved for addressing.
65 *
66 * Real-world software should use ptrauth.h when it needs to manually sign or
67 * auth pointers. But for testing purposes we need clang to emit specific
68 * ptrauth instructions, so we use inline asm here instead.
69 *
70 * Likewise clang would normally combine the "naked" auth and brk testcases as
71 * part of a sequence like:
72 *
73 * output = auth(...);
74 * if (output is poisoned) {
75 * brk(PTRAUTH_FAILURE_COMMENT);
76 * }
77 *
78 * On auth failure, CPUs that implement FEAT_FPAC will trap immediately at the
79 * auth instruction, and CPUs without FEAT_FPAC will trap at the later brk
80 * instruction. But again, for testing purposes we want these to be two
81 * discrete cases. (On FPAC-enabled CPUs, the kernel should treat *both* traps
82 * as ptrauth failure, even if we don't expect the latter to be reachable in
83 * real-world software.)
84 */
85
86 static void
naked_auth(void)87 naked_auth(void)
88 {
89 asm volatile (
90 "mov x0, #0" "\n"
91 "paciza x0" "\n"
92 "eor x0, x0, (1 << 63)" "\n"
93 "autiza x0"
94 :
95 :
96 : "x0"
97 );
98 }
99
100 static void
ptrauth_brk(void)101 ptrauth_brk(void)
102 {
103 asm volatile ("brk 0xc470");
104 }
105
106 static void
combined_branch_auth(void)107 combined_branch_auth(void)
108 {
109 asm volatile (
110 "adr x0, 1f" "\n"
111 "paciza x0" "\n"
112 "eor x0, x0, (1 << 63)" "\n"
113 "braaz x0" "\n"
114 "1:"
115 :
116 :
117 : "x0"
118 );
119 }
120
121 static void
combined_load_auth(void)122 combined_load_auth(void)
123 {
124 asm volatile (
125 "mov x0, sp" "\n"
126 "pacdza x0" "\n"
127 "eor x0, x0, (1 << 54)" "\n"
128 "ldraa x0, [x0]" "\n"
129 :
130 :
131 : "x0"
132 );
133 }
134
135 static void
run_pac_exception_test(void (* ptrauth_failure_fn)(void))136 run_pac_exception_test(void (*ptrauth_failure_fn)(void))
137 {
138
139 pid_t pid = fork();
140 T_QUIET; T_ASSERT_POSIX_SUCCESS(pid, "fork");
141
142 if (pid == 0) {
143 mach_port_t exc_port = create_exception_port(EXC_MASK_BAD_ACCESS | EXC_MASK_BREAKPOINT);
144 run_exception_handler(exc_port, exception_handler);
145
146 ptrauth_failure_fn();
147 /* ptrauth_failure_fn() should have raised an uncatchable exception */
148 T_FAIL("child ran to completion");
149 } else {
150 int status;
151 int err = waitpid(pid, &status, 0);
152 T_QUIET; T_ASSERT_POSIX_SUCCESS(err, "waitpid");
153
154 T_EXPECT_TRUE(WIFSIGNALED(status), "child terminated due to signal");
155 T_EXPECT_EQ(SIGKILL, WTERMSIG(status), "child terminated due to SIGKILL");
156 }
157 }
158 #endif //__arm64e__
159
160 T_DECL(pac_exception_naked_auth,
161 "Test the com.apple.private.pac.exception entitlement (naked auth failure)",
162 T_META_REQUIRES_SYSCTL_EQ("hw.optional.arm.FEAT_FPAC", 1), T_META_TAG_VM_NOT_ELIGIBLE)
163 {
164 #if __arm64e__
165 run_pac_exception_test(naked_auth);
166 #else
167 T_SKIP("Running on non-arm64e target, skipping...");
168 #endif
169 }
170
171
172 T_DECL(pac_exception_ptrauth_brk,
173 "Test the com.apple.private.pac.exception entitlement (brk with comment indicating ptrauth failure)", T_META_TAG_VM_NOT_ELIGIBLE)
174 {
175 #if __arm64e__
176 run_pac_exception_test(ptrauth_brk);
177 #else
178 T_SKIP("Running on non-arm64e target, skipping...");
179 #endif
180 }
181
182 T_DECL(pac_exception_combined_branch_auth,
183 "Test the com.apple.private.pac.exception entitlement (combined branch + auth failure)", T_META_TAG_VM_NOT_ELIGIBLE)
184 {
185 #if __arm64e__
186 run_pac_exception_test(combined_branch_auth);
187 #else
188 T_SKIP("Running on non-arm64e target, skipping...");
189 #endif
190 }
191
192 T_DECL(pac_exception_combined_load_auth,
193 "Test the com.apple.private.pac.exception entitlement (combined branch + auth failure)", T_META_TAG_VM_NOT_ELIGIBLE)
194 {
195 #if __arm64e__
196 run_pac_exception_test(combined_load_auth);
197 #else
198 T_SKIP("Running on non-arm64e target, skipping...");
199 #endif
200 }
201