1 /*
2 * Copyright (c) 2017 Fujitsu Ltd.
3 * Author: Xiao Yang <yangx.jy@cn.fujitsu.com>
4 *
5 * This program is free software: you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.*
17 */
18
19 /*
20 * Description:
21 * fcntl(2) manpage states that an unprivileged user could not set the
22 * pipe capacity above the limit in /proc/sys/fs/pipe-max-size. However,
23 * an unprivileged user could create a pipe whose initial capacity exceeds
24 * the limit. We add a regression test to check that pipe-max-size caps
25 * the initial allocation for a new pipe for unprivileged users, but not
26 * for privileged users.
27 *
28 * This kernel bug has been fixed by:
29 *
30 * commit 086e774a57fba4695f14383c0818994c0b31da7c
31 * Author: Michael Kerrisk (man-pages) <mtk.manpages@gmail.com>
32 * Date: Tue Oct 11 13:53:43 2016 -0700
33 *
34 * pipe: cap initial pipe capacity according to pipe-max-size limit
35 */
36
37 #include <errno.h>
38 #include <sys/types.h>
39 #include <pwd.h>
40 #include <unistd.h>
41 #include <fcntl.h>
42 #include <stdlib.h>
43
44 #include "lapi/fcntl.h"
45 #include "tst_test.h"
46
47 static int pipe_max_unpriv;
48 static int test_max_unpriv;
49 static int test_max_priv;
50 static struct passwd *pw;
51 static struct tcase {
52 int *exp_sz;
53 int exp_usr;
54 char *des;
55 } tcases[] = {
56 {&test_max_unpriv, 1, "an unprivileged user"},
57 {&test_max_priv, 0, "a privileged user"}
58 };
59
setup(void)60 static void setup(void)
61 {
62 test_max_unpriv = getpagesize();
63 test_max_priv = test_max_unpriv * 16;
64
65 if (!access("/proc/sys/fs/pipe-max-size", F_OK)) {
66 SAFE_FILE_SCANF("/proc/sys/fs/pipe-max-size", "%d",
67 &pipe_max_unpriv);
68 SAFE_FILE_PRINTF("/proc/sys/fs/pipe-max-size", "%d",
69 test_max_unpriv);
70 } else {
71 tst_brk(TCONF, "/proc/sys/fs/pipe-max-size doesn't exist");
72 }
73
74 pw = SAFE_GETPWNAM("nobody");
75 }
76
cleanup(void)77 static void cleanup(void)
78 {
79 SAFE_FILE_PRINTF("/proc/sys/fs/pipe-max-size", "%d", pipe_max_unpriv);
80 }
81
verify_pipe_size(int exp_pip_sz,char * desp)82 static int verify_pipe_size(int exp_pip_sz, char *desp)
83 {
84 int get_size;
85 int fds[2];
86
87 SAFE_PIPE(fds);
88
89 get_size = fcntl(fds[1], F_GETPIPE_SZ);
90 if (get_size == -1) {
91 tst_res(TFAIL | TERRNO, "fcntl(2) with F_GETPIPE_SZ failed");
92 goto end;
93 }
94
95 if (get_size != exp_pip_sz) {
96 tst_res(TFAIL, "%s init the capacity of a pipe to %d "
97 "unexpectedly, expected %d", desp, get_size,
98 exp_pip_sz);
99 } else {
100 tst_res(TPASS, "%s init the capacity of a pipe to %d "
101 "successfully", desp, exp_pip_sz);
102 }
103
104 end:
105 if (fds[0] > 0)
106 SAFE_CLOSE(fds[0]);
107
108 if (fds[1] > 0)
109 SAFE_CLOSE(fds[1]);
110
111 exit(0);
112 }
113
do_test(unsigned int n)114 static void do_test(unsigned int n)
115 {
116 struct tcase *tc = &tcases[n];
117
118 if (!SAFE_FORK()) {
119 if (tc->exp_usr)
120 SAFE_SETUID(pw->pw_uid);
121
122 verify_pipe_size(*tc->exp_sz, tc->des);
123 }
124
125 tst_reap_children();
126 }
127
128 static struct tst_test test = {
129 .min_kver = "2.6.35",
130 .needs_root = 1,
131 .forks_child = 1,
132 .tcnt = ARRAY_SIZE(tcases),
133 .setup = setup,
134 .cleanup = cleanup,
135 .test = do_test
136 };
137