1 // SPDX-License-Identifier: GPL-2.0
2
3 /*
4 * Copyright (C) 2020 Google LLC.
5 */
6
7 #include <stdio.h>
8 #include <stdlib.h>
9 #include <unistd.h>
10 #include <sys/wait.h>
11 #include <test_progs.h>
12 #include <linux/ring_buffer.h>
13
14 #include "ima.skel.h"
15
16 #define MAX_SAMPLES 4
17
_run_measured_process(const char * measured_dir,u32 * monitored_pid,const char * cmd)18 static int _run_measured_process(const char *measured_dir, u32 *monitored_pid,
19 const char *cmd)
20 {
21 int child_pid, child_status;
22
23 child_pid = fork();
24 if (child_pid == 0) {
25 *monitored_pid = getpid();
26 execlp("./ima_setup.sh", "./ima_setup.sh", cmd, measured_dir,
27 NULL);
28 exit(errno);
29
30 } else if (child_pid > 0) {
31 waitpid(child_pid, &child_status, 0);
32 return WEXITSTATUS(child_status);
33 }
34
35 return -EINVAL;
36 }
37
run_measured_process(const char * measured_dir,u32 * monitored_pid)38 static int run_measured_process(const char *measured_dir, u32 *monitored_pid)
39 {
40 return _run_measured_process(measured_dir, monitored_pid, "run");
41 }
42
43 static u64 ima_hash_from_bpf[MAX_SAMPLES];
44 static int ima_hash_from_bpf_idx;
45
process_sample(void * ctx,void * data,size_t len)46 static int process_sample(void *ctx, void *data, size_t len)
47 {
48 if (ima_hash_from_bpf_idx >= MAX_SAMPLES)
49 return -ENOSPC;
50
51 ima_hash_from_bpf[ima_hash_from_bpf_idx++] = *((u64 *)data);
52 return 0;
53 }
54
test_init(struct ima__bss * bss)55 static void test_init(struct ima__bss *bss)
56 {
57 ima_hash_from_bpf_idx = 0;
58
59 bss->use_ima_file_hash = false;
60 bss->enable_bprm_creds_for_exec = false;
61 bss->enable_kernel_read_file = false;
62 bss->test_deny = false;
63 }
64
test_test_ima(void)65 void test_test_ima(void)
66 {
67 char measured_dir_template[] = "/tmp/ima_measuredXXXXXX";
68 struct ring_buffer *ringbuf = NULL;
69 const char *measured_dir;
70 u64 bin_true_sample;
71 char cmd[256];
72
73 int err, duration = 0, fresh_digest_idx = 0;
74 struct ima *skel = NULL;
75
76 skel = ima__open_and_load();
77 if (CHECK(!skel, "skel_load", "skeleton failed\n"))
78 goto close_prog;
79
80 ringbuf = ring_buffer__new(bpf_map__fd(skel->maps.ringbuf),
81 process_sample, NULL, NULL);
82 if (!ASSERT_OK_PTR(ringbuf, "ringbuf"))
83 goto close_prog;
84
85 err = ima__attach(skel);
86 if (CHECK(err, "attach", "attach failed: %d\n", err))
87 goto close_prog;
88
89 measured_dir = mkdtemp(measured_dir_template);
90 if (CHECK(measured_dir == NULL, "mkdtemp", "err %d\n", errno))
91 goto close_prog;
92
93 snprintf(cmd, sizeof(cmd), "./ima_setup.sh setup %s", measured_dir);
94 err = system(cmd);
95 if (CHECK(err, "failed to run command", "%s, errno = %d\n", cmd, errno))
96 goto close_clean;
97
98 /*
99 * Test #1
100 * - Goal: obtain a sample with the bpf_ima_inode_hash() helper
101 * - Expected result: 1 sample (/bin/true)
102 */
103 test_init(skel->bss);
104 err = run_measured_process(measured_dir, &skel->bss->monitored_pid);
105 if (CHECK(err, "run_measured_process #1", "err = %d\n", err))
106 goto close_clean;
107
108 err = ring_buffer__consume(ringbuf);
109 ASSERT_EQ(err, 1, "num_samples_or_err");
110 ASSERT_NEQ(ima_hash_from_bpf[0], 0, "ima_hash");
111
112 /*
113 * Test #2
114 * - Goal: obtain samples with the bpf_ima_file_hash() helper
115 * - Expected result: 2 samples (./ima_setup.sh, /bin/true)
116 */
117 test_init(skel->bss);
118 skel->bss->use_ima_file_hash = true;
119 err = run_measured_process(measured_dir, &skel->bss->monitored_pid);
120 if (CHECK(err, "run_measured_process #2", "err = %d\n", err))
121 goto close_clean;
122
123 err = ring_buffer__consume(ringbuf);
124 ASSERT_EQ(err, 2, "num_samples_or_err");
125 ASSERT_NEQ(ima_hash_from_bpf[0], 0, "ima_hash");
126 ASSERT_NEQ(ima_hash_from_bpf[1], 0, "ima_hash");
127 bin_true_sample = ima_hash_from_bpf[1];
128
129 /*
130 * Test #3
131 * - Goal: confirm that bpf_ima_inode_hash() returns a non-fresh digest
132 * - Expected result:
133 * 1 sample (/bin/true: fresh) if commit 62622dab0a28 applied
134 * 2 samples (/bin/true: non-fresh, fresh) if commit 62622dab0a28 is
135 * not applied
136 *
137 * If commit 62622dab0a28 ("ima: return IMA digest value only when
138 * IMA_COLLECTED flag is set") is applied, bpf_ima_inode_hash() refuses
139 * to give a non-fresh digest, hence the correct result is 1 instead of
140 * 2.
141 */
142 test_init(skel->bss);
143
144 err = _run_measured_process(measured_dir, &skel->bss->monitored_pid,
145 "modify-bin");
146 if (CHECK(err, "modify-bin #3", "err = %d\n", err))
147 goto close_clean;
148
149 skel->bss->enable_bprm_creds_for_exec = true;
150 err = run_measured_process(measured_dir, &skel->bss->monitored_pid);
151 if (CHECK(err, "run_measured_process #3", "err = %d\n", err))
152 goto close_clean;
153
154 err = ring_buffer__consume(ringbuf);
155 ASSERT_GE(err, 1, "num_samples_or_err");
156 if (err == 2) {
157 ASSERT_NEQ(ima_hash_from_bpf[0], 0, "ima_hash");
158 ASSERT_EQ(ima_hash_from_bpf[0], bin_true_sample,
159 "sample_equal_or_err");
160 fresh_digest_idx = 1;
161 }
162
163 ASSERT_NEQ(ima_hash_from_bpf[fresh_digest_idx], 0, "ima_hash");
164 /* IMA refreshed the digest. */
165 ASSERT_NEQ(ima_hash_from_bpf[fresh_digest_idx], bin_true_sample,
166 "sample_equal_or_err");
167
168 /*
169 * Test #4
170 * - Goal: verify that bpf_ima_file_hash() returns a fresh digest
171 * - Expected result: 4 samples (./ima_setup.sh: fresh, fresh;
172 * /bin/true: fresh, fresh)
173 */
174 test_init(skel->bss);
175 skel->bss->use_ima_file_hash = true;
176 skel->bss->enable_bprm_creds_for_exec = true;
177 err = run_measured_process(measured_dir, &skel->bss->monitored_pid);
178 if (CHECK(err, "run_measured_process #4", "err = %d\n", err))
179 goto close_clean;
180
181 err = ring_buffer__consume(ringbuf);
182 ASSERT_EQ(err, 4, "num_samples_or_err");
183 ASSERT_NEQ(ima_hash_from_bpf[0], 0, "ima_hash");
184 ASSERT_NEQ(ima_hash_from_bpf[1], 0, "ima_hash");
185 ASSERT_NEQ(ima_hash_from_bpf[2], 0, "ima_hash");
186 ASSERT_NEQ(ima_hash_from_bpf[3], 0, "ima_hash");
187 ASSERT_NEQ(ima_hash_from_bpf[2], bin_true_sample,
188 "sample_different_or_err");
189 ASSERT_EQ(ima_hash_from_bpf[3], ima_hash_from_bpf[2],
190 "sample_equal_or_err");
191
192 skel->bss->use_ima_file_hash = false;
193 skel->bss->enable_bprm_creds_for_exec = false;
194 err = _run_measured_process(measured_dir, &skel->bss->monitored_pid,
195 "restore-bin");
196 if (CHECK(err, "restore-bin #3", "err = %d\n", err))
197 goto close_clean;
198
199 /*
200 * Test #5
201 * - Goal: obtain a sample from the kernel_read_file hook
202 * - Expected result: 2 samples (./ima_setup.sh, policy_test)
203 */
204 test_init(skel->bss);
205 skel->bss->use_ima_file_hash = true;
206 skel->bss->enable_kernel_read_file = true;
207 err = _run_measured_process(measured_dir, &skel->bss->monitored_pid,
208 "load-policy");
209 if (CHECK(err, "run_measured_process #5", "err = %d\n", err))
210 goto close_clean;
211
212 err = ring_buffer__consume(ringbuf);
213 ASSERT_EQ(err, 2, "num_samples_or_err");
214 ASSERT_NEQ(ima_hash_from_bpf[0], 0, "ima_hash");
215 ASSERT_NEQ(ima_hash_from_bpf[1], 0, "ima_hash");
216
217 /*
218 * Test #6
219 * - Goal: ensure that the kernel_read_file hook denies an operation
220 * - Expected result: 0 samples
221 */
222 test_init(skel->bss);
223 skel->bss->enable_kernel_read_file = true;
224 skel->bss->test_deny = true;
225 err = _run_measured_process(measured_dir, &skel->bss->monitored_pid,
226 "load-policy");
227 if (CHECK(!err, "run_measured_process #6", "err = %d\n", err))
228 goto close_clean;
229
230 err = ring_buffer__consume(ringbuf);
231 ASSERT_EQ(err, 0, "num_samples_or_err");
232
233 close_clean:
234 snprintf(cmd, sizeof(cmd), "./ima_setup.sh cleanup %s", measured_dir);
235 err = system(cmd);
236 CHECK(err, "failed to run command", "%s, errno = %d\n", cmd, errno);
237 close_prog:
238 ring_buffer__free(ringbuf);
239 ima__destroy(skel);
240 }
241