1 /*
2 * Copyright (c) 2021 Alexey Dobriyan <adobriyan@gmail.com>
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16 /*
17 * Test that "mount -t proc -o subset=pid" hides everything but pids,
18 * /proc/self and /proc/thread-self.
19 */
20 #undef NDEBUG
21 #include <assert.h>
22 #include <errno.h>
23 #include <sched.h>
24 #include <stdbool.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <sys/mount.h>
28 #include <sys/types.h>
29 #include <sys/stat.h>
30 #include <fcntl.h>
31 #include <dirent.h>
32 #include <unistd.h>
33 #include <stdio.h>
34
35 static inline bool streq(const char *a, const char *b)
36 {
37 return strcmp(a, b) == 0;
38 }
39
40 static void make_private_proc(void)
41 {
42 if (unshare(CLONE_NEWNS) == -1) {
43 if (errno == ENOSYS || errno == EPERM) {
44 exit(4);
45 }
46 exit(1);
47 }
48 if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) == -1) {
49 exit(1);
50 }
51 if (mount(NULL, "/proc", "proc", 0, "subset=pid") == -1) {
52 exit(1);
53 }
54 }
55
56 static bool string_is_pid(const char *s)
57 {
58 while (1) {
59 switch (*s++) {
60 case '':case '1':case '2':case '3':case '4':
61 case '5':case '6':case '7':case '8':case '9':
62 continue;
63
64 case '\0':
65 return true;
66
67 default:
68 return false;
69 }
70 }
71 }
72
73 int main(void)
74 {
75 make_private_proc();
76
77 DIR *d = opendir("/proc");
78 assert(d);
79
80 struct dirent *de;
81
82 bool dot = false;
83 bool dot_dot = false;
84 bool self = false;
85 bool thread_self = false;
86
87 while ((de = readdir(d))) {
88 if (streq(de->d_name, ".")) {
89 assert(!dot);
90 dot = true;
91 assert(de->d_type == DT_DIR);
92 } else if (streq(de->d_name, "..")) {
93 assert(!dot_dot);
94 dot_dot = true;
95 assert(de->d_type == DT_DIR);
96 } else if (streq(de->d_name, "self")) {
97 assert(!self);
98 self = true;
99 assert(de->d_type == DT_LNK);
100 } else if (streq(de->d_name, "thread-self")) {
101 assert(!thread_self);
102 thread_self = true;
103 assert(de->d_type == DT_LNK);
104 } else {
105 if (!string_is_pid(de->d_name)) {
106 fprintf(stderr, "d_name '%s'\n", de->d_name);
107 assert(0);
108 }
109 assert(de->d_type == DT_DIR);
110 }
111 }
112
113 char c;
114 int rv = readlink("/proc/cpuinfo", &c, 1);
115 assert(rv == -1 && errno == ENOENT);
116
117 int fd = open("/proc/cpuinfo", O_RDONLY);
118 assert(fd == -1 && errno == ENOENT);
119
120 return 0;
121 }
122
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