1 /* Copyright (c) 2014 Red Hat, Inc.
2  *
3  * This program is free software: you can redistribute it and/or modify
4  * it under the terms of version 2 the GNU General Public License as
5  * published by the Free Software Foundation.
6  *
7  * This program is distributed in the hope that it will be useful,
8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10  * GNU General Public License for more details.
11  *
12  * You should have received a copy of the GNU General Public License
13  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
14  ***********************************************************************
15  * File: mountns03.c
16  *
17  * Tests a slave mount: slave mount is like a shared mount except that
18  * mount and umount events only propagate towards it.
19  *
20  * Description:
21  * 1. Creates directories "A", "B" and files "A/A", "B/B"
22  * 2. Unshares mount namespace and makes it private (so mounts/umounts
23  *    have no effect on a real system)
24  * 3. Bind mounts directory "A" to itself
25  * 4. Makes directory "A" shared
26  * 5. Clones a new child process with CLONE_NEWNS flag and makes "A"
27  *    a slave mount
28  * 6. There are two testcases (where X is parent namespace and Y child
29  *    namespace):
30  *    1)
31  *	X: bind mounts "B" to "A"
32  *	Y: must see the file "A/B"
33  *	X: umounts "A"
34  *    2)
35  *	Y: bind mounts "B" to "A"
36  *	X: must see only the "A/A" and must not see "A/B" (as slave
37  *	   mount does not forward propagation)
38  *	Y: umounts "A"
39  ***********************************************************************/
40 
41 #define _GNU_SOURCE
42 #include <sys/wait.h>
43 #include <sys/mount.h>
44 #include <stdio.h>
45 #include <unistd.h>
46 #include <errno.h>
47 #include "test.h"
48 #include "libclone.h"
49 #include "safe_macros.h"
50 #include "mountns_helper.h"
51 
52 
53 char *TCID	= "mountns03";
54 int TST_TOTAL	= 2;
55 
56 
57 #if defined(MS_SHARED) && defined(MS_PRIVATE) \
58     && defined(MS_REC) && defined(MS_SLAVE)
59 
child_func(void * arg LTP_ATTRIBUTE_UNUSED)60 int child_func(void *arg LTP_ATTRIBUTE_UNUSED)
61 {
62 	int ret = 0;
63 
64 	/* makes mount DIRA a slave of DIRA (all slave mounts have
65 	 * a master mount which is a shared mount) */
66 	if (mount("none", DIRA, "none", MS_SLAVE, NULL) == -1) {
67 		perror("mount");
68 		return 1;
69 	}
70 
71 	TST_SAFE_CHECKPOINT_WAKE_AND_WAIT(NULL, 0);
72 
73 	/* checks that shared mounts propagates to slave mount */
74 	if (access(DIRA"/B", F_OK) == -1)
75 		ret = 2;
76 
77 	TST_SAFE_CHECKPOINT_WAKE_AND_WAIT(NULL, 0);
78 
79 	/* bind mounts DIRB to DIRA making contents of DIRB visible
80 	 * in DIRA */
81 	if (mount(DIRB, DIRA, "none", MS_BIND, NULL) == -1) {
82 		perror("mount");
83 		return 1;
84 	}
85 
86 	TST_SAFE_CHECKPOINT_WAKE_AND_WAIT(NULL, 0);
87 
88 	umount(DIRA);
89 	return ret;
90 }
91 
test(void)92 static void test(void)
93 {
94 	int status;
95 
96 	/* unshares the mount ns */
97 	if (unshare(CLONE_NEWNS) == -1)
98 		tst_brkm(TBROK | TERRNO, cleanup, "unshare failed");
99 	/* makes sure parent mounts/umounts have no effect on a real system */
100 	SAFE_MOUNT(cleanup, "none", "/", "none", MS_REC|MS_PRIVATE, NULL);
101 
102 	/* bind mounts DIRA to itself */
103 	SAFE_MOUNT(cleanup, DIRA, DIRA, "none", MS_BIND, NULL);
104 
105 	/* makes mount DIRA shared */
106 	SAFE_MOUNT(cleanup, "none", DIRA, "none", MS_SHARED, NULL);
107 
108 	if (do_clone_tests(CLONE_NEWNS, child_func, NULL, NULL, NULL) == -1)
109 		tst_brkm(TBROK | TERRNO, cleanup, "clone failed");
110 
111 	/* waits for child to make a slave mount */
112 	TST_SAFE_CHECKPOINT_WAIT(cleanup, 0);
113 
114 	/* bind mounts DIRB to DIRA making contents of DIRB visible
115 	 * in DIRA */
116 	SAFE_MOUNT(cleanup, DIRB, DIRA, "none", MS_BIND, NULL);
117 
118 	TST_SAFE_CHECKPOINT_WAKE_AND_WAIT(cleanup, 0);
119 
120 	SAFE_UMOUNT(cleanup, DIRA);
121 
122 	TST_SAFE_CHECKPOINT_WAKE_AND_WAIT(cleanup, 0);
123 
124 	/* checks that slave mount doesn't propagate to shared mount */
125 	if ((access(DIRA"/A", F_OK) == 0) && (access(DIRA"/B", F_OK) == -1))
126 		tst_resm(TPASS, "propagation from slave mount passed");
127 	else
128 		tst_resm(TFAIL, "propagation form slave mount failed");
129 
130 	TST_SAFE_CHECKPOINT_WAKE(cleanup, 0);
131 
132 
133 	SAFE_WAIT(cleanup, &status);
134 	if (WIFEXITED(status)) {
135 		if (WEXITSTATUS(status) == 0)
136 			tst_resm(TPASS, "propagation to slave mount passed");
137 		else
138 			tst_resm(TFAIL, "propagation to slave mount failed");
139 	}
140 	if (WIFSIGNALED(status)) {
141 		tst_resm(TBROK, "child was killed with signal %s",
142 			 tst_strsig(WTERMSIG(status)));
143 		return;
144 	}
145 
146 	SAFE_UMOUNT(cleanup, DIRA);
147 }
148 
main(int argc,char * argv[])149 int main(int argc, char *argv[])
150 {
151 	int lc;
152 
153 	tst_parse_opts(argc, argv, NULL, NULL);
154 
155 	setup();
156 
157 	for (lc = 0; TEST_LOOPING(lc); lc++)
158 		test();
159 
160 	cleanup();
161 	tst_exit();
162 }
163 
164 #else
main(void)165 int main(void)
166 {
167 	tst_brkm(TCONF, NULL, "needed mountflags are not defined");
168 }
169 #endif
170