1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) 2017 Fujitsu Ltd.
4 * Author: Xiao Yang <yangx.jy@cn.fujitsu.com>
5 */
6
7 /*
8 * Description:
9 * fcntl(2) manpage states that an unprivileged user could not set the
10 * pipe capacity above the limit in /proc/sys/fs/pipe-max-size. However,
11 * an unprivileged user could create a pipe whose initial capacity exceeds
12 * the limit. We add a regression test to check that pipe-max-size caps
13 * the initial allocation for a new pipe for unprivileged users, but not
14 * for privileged users.
15 *
16 * This kernel bug has been fixed by:
17 *
18 * commit 086e774a57fba4695f14383c0818994c0b31da7c
19 * Author: Michael Kerrisk (man-pages) <mtk.manpages@gmail.com>
20 * Date: Tue Oct 11 13:53:43 2016 -0700
21 *
22 * pipe: cap initial pipe capacity according to pipe-max-size limit
23 */
24
25 #include <errno.h>
26 #include <sys/types.h>
27 #include <pwd.h>
28 #include <unistd.h>
29 #include <stdlib.h>
30
31 #include "lapi/fcntl.h"
32 #include "tst_test.h"
33
34 static int pipe_max_unpriv;
35 static int test_max_unpriv;
36 static int test_max_priv;
37 static struct passwd *pw;
38 static struct tcase {
39 int *exp_sz;
40 int exp_usr;
41 char *des;
42 } tcases[] = {
43 {&test_max_unpriv, 1, "an unprivileged user"},
44 {&test_max_priv, 0, "a privileged user"}
45 };
46
setup(void)47 static void setup(void)
48 {
49 test_max_unpriv = getpagesize();
50 test_max_priv = test_max_unpriv * 16;
51
52 if (!access("/proc/sys/fs/pipe-max-size", F_OK)) {
53 SAFE_FILE_SCANF("/proc/sys/fs/pipe-max-size", "%d",
54 &pipe_max_unpriv);
55 SAFE_FILE_PRINTF("/proc/sys/fs/pipe-max-size", "%d",
56 test_max_unpriv);
57 } else {
58 tst_brk(TCONF, "/proc/sys/fs/pipe-max-size doesn't exist");
59 }
60
61 pw = SAFE_GETPWNAM("nobody");
62 }
63
cleanup(void)64 static void cleanup(void)
65 {
66 SAFE_FILE_PRINTF("/proc/sys/fs/pipe-max-size", "%d", pipe_max_unpriv);
67 }
68
verify_pipe_size(int exp_pip_sz,char * desp)69 static int verify_pipe_size(int exp_pip_sz, char *desp)
70 {
71 int get_size;
72 int fds[2];
73
74 SAFE_PIPE(fds);
75
76 get_size = fcntl(fds[1], F_GETPIPE_SZ);
77 if (get_size == -1) {
78 tst_res(TFAIL | TERRNO, "fcntl(2) with F_GETPIPE_SZ failed");
79 goto end;
80 }
81
82 if (get_size != exp_pip_sz) {
83 tst_res(TFAIL, "%s init the capacity of a pipe to %d "
84 "unexpectedly, expected %d", desp, get_size,
85 exp_pip_sz);
86 } else {
87 tst_res(TPASS, "%s init the capacity of a pipe to %d "
88 "successfully", desp, exp_pip_sz);
89 }
90
91 end:
92 if (fds[0] > 0)
93 SAFE_CLOSE(fds[0]);
94
95 if (fds[1] > 0)
96 SAFE_CLOSE(fds[1]);
97
98 exit(0);
99 }
100
do_test(unsigned int n)101 static void do_test(unsigned int n)
102 {
103 struct tcase *tc = &tcases[n];
104
105 if (!SAFE_FORK()) {
106 if (tc->exp_usr)
107 SAFE_SETUID(pw->pw_uid);
108
109 verify_pipe_size(*tc->exp_sz, tc->des);
110 }
111
112 tst_reap_children();
113 }
114
115 static struct tst_test test = {
116 .min_kver = "2.6.35",
117 .needs_root = 1,
118 .forks_child = 1,
119 .tcnt = ARRAY_SIZE(tcases),
120 .setup = setup,
121 .cleanup = cleanup,
122 .test = do_test,
123 .tags = (const struct tst_tag[]) {
124 {"linux-git", "086e774a57fb"},
125 {}
126 }
127 };
128