1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
|
/* SPDX-License-Identifier: LGPL-2.1+ */
#include <netinet/in.h>
#include <pwd.h>
#include <sys/capability.h>
#include <sys/prctl.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <unistd.h>
#include "alloc-util.h"
#include "capability-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "macro.h"
#include "missing_prctl.h"
#include "parse-util.h"
#include "tests.h"
#include "util.h"
static uid_t test_uid = -1;
static gid_t test_gid = -1;
#if HAS_FEATURE_ADDRESS_SANITIZER
/* Keep CAP_SYS_PTRACE when running under Address Sanitizer */
static const uint64_t test_flags = UINT64_C(1) << CAP_SYS_PTRACE;
#else
/* We keep CAP_DAC_OVERRIDE to avoid errors with gcov when doing test coverage */
static const uint64_t test_flags = UINT64_C(1) << CAP_DAC_OVERRIDE;
#endif
/* verify cap_last_cap() against /proc/sys/kernel/cap_last_cap */
static void test_last_cap_file(void) {
_cleanup_free_ char *content = NULL;
unsigned long val = 0;
int r;
r = read_one_line_file("/proc/sys/kernel/cap_last_cap", &content);
assert_se(r >= 0);
r = safe_atolu(content, &val);
assert_se(r >= 0);
assert_se(val != 0);
assert_se(val == cap_last_cap());
}
/* verify cap_last_cap() against syscall probing */
static void test_last_cap_probe(void) {
unsigned long p = (unsigned long)CAP_LAST_CAP;
if (prctl(PR_CAPBSET_READ, p) < 0) {
for (p--; p > 0; p --)
if (prctl(PR_CAPBSET_READ, p) >= 0)
break;
} else {
for (;; p++)
if (prctl(PR_CAPBSET_READ, p+1) < 0)
break;
}
assert_se(p != 0);
assert_se(p == cap_last_cap());
}
static void fork_test(void (*test_func)(void)) {
pid_t pid = 0;
pid = fork();
assert_se(pid >= 0);
if (pid == 0) {
test_func();
exit(EXIT_SUCCESS);
} else if (pid > 0) {
int status;
assert_se(waitpid(pid, &status, 0) > 0);
assert_se(WIFEXITED(status) && WEXITSTATUS(status) == 0);
}
}
static void show_capabilities(void) {
cap_t caps;
char *text;
caps = cap_get_proc();
assert_se(caps);
text = cap_to_text(caps, NULL);
assert_se(text);
log_info("Capabilities:%s", text);
cap_free(caps);
cap_free(text);
}
static int setup_tests(bool *run_ambient) {
struct passwd *nobody;
int r;
nobody = getpwnam(NOBODY_USER_NAME);
if (!nobody)
return log_error_errno(errno, "Could not find nobody user: %m");
test_uid = nobody->pw_uid;
test_gid = nobody->pw_gid;
*run_ambient = false;
r = prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0);
/* There's support for PR_CAP_AMBIENT if the prctl() call
* succeeded or error code was something else than EINVAL. The
* EINVAL check should be good enough to rule out false
* positives. */
if (r >= 0 || errno != EINVAL)
*run_ambient = true;
return 0;
}
static void test_drop_privileges_keep_net_raw(void) {
int sock;
sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
assert_se(sock >= 0);
safe_close(sock);
assert_se(drop_privileges(test_uid, test_gid, test_flags | (1ULL << CAP_NET_RAW)) >= 0);
assert_se(getuid() == test_uid);
assert_se(getgid() == test_gid);
show_capabilities();
sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
assert_se(sock >= 0);
safe_close(sock);
}
static void test_drop_privileges_dontkeep_net_raw(void) {
int sock;
sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
assert_se(sock >= 0);
safe_close(sock);
assert_se(drop_privileges(test_uid, test_gid, test_flags) >= 0);
assert_se(getuid() == test_uid);
assert_se(getgid() == test_gid);
show_capabilities();
sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
assert_se(sock < 0);
}
static void test_drop_privileges_fail(void) {
assert_se(drop_privileges(test_uid, test_gid, test_flags) >= 0);
assert_se(getuid() == test_uid);
assert_se(getgid() == test_gid);
assert_se(drop_privileges(test_uid, test_gid, test_flags) < 0);
assert_se(drop_privileges(0, 0, test_flags) < 0);
}
static void test_drop_privileges(void) {
fork_test(test_drop_privileges_keep_net_raw);
fork_test(test_drop_privileges_dontkeep_net_raw);
fork_test(test_drop_privileges_fail);
}
static void test_have_effective_cap(void) {
assert_se(have_effective_cap(CAP_KILL));
assert_se(have_effective_cap(CAP_CHOWN));
assert_se(drop_privileges(test_uid, test_gid, test_flags | (1ULL << CAP_KILL)) >= 0);
assert_se(getuid() == test_uid);
assert_se(getgid() == test_gid);
assert_se(have_effective_cap(CAP_KILL));
assert_se(!have_effective_cap(CAP_CHOWN));
}
static void test_update_inherited_set(void) {
cap_t caps;
uint64_t set = 0;
cap_flag_value_t fv;
caps = cap_get_proc();
assert_se(caps);
set = (UINT64_C(1) << CAP_CHOWN);
assert_se(!capability_update_inherited_set(caps, set));
assert_se(!cap_get_flag(caps, CAP_CHOWN, CAP_INHERITABLE, &fv));
assert(fv == CAP_SET);
cap_free(caps);
}
static void test_set_ambient_caps(void) {
cap_t caps;
uint64_t set = 0;
cap_flag_value_t fv;
assert_se(prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_CHOWN, 0, 0) == 0);
set = (UINT64_C(1) << CAP_CHOWN);
assert_se(!capability_ambient_set_apply(set, true));
caps = cap_get_proc();
assert_se(!cap_get_flag(caps, CAP_CHOWN, CAP_INHERITABLE, &fv));
assert(fv == CAP_SET);
cap_free(caps);
assert_se(prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_CHOWN, 0, 0) == 1);
}
int main(int argc, char *argv[]) {
bool run_ambient;
test_setup_logging(LOG_INFO);
test_last_cap_file();
test_last_cap_probe();
log_info("have ambient caps: %s", yes_no(ambient_capabilities_supported()));
if (getuid() != 0)
return log_tests_skipped("not running as root");
if (setup_tests(&run_ambient) < 0)
return log_tests_skipped("setup failed");
show_capabilities();
test_drop_privileges();
test_update_inherited_set();
fork_test(test_have_effective_cap);
if (run_ambient)
fork_test(test_set_ambient_caps);
return 0;
}
|
