1 /* Test for the memfd_create system call.
2 Copyright (C) 2017-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library 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 GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <errno.h>
20 #include <fcntl.h>
21 #include <stdbool.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <support/check.h>
26 #include <support/support.h>
27 #include <support/test-driver.h>
28 #include <support/xunistd.h>
29 #include <sys/mman.h>
30
31 /* Return true if the descriptor has the FD_CLOEXEC flag set. */
32 static bool
is_cloexec(int fd)33 is_cloexec (int fd)
34 {
35 int flags = fcntl (fd, F_GETFD);
36 TEST_VERIFY (flags >= 0);
37 return flags & FD_CLOEXEC;
38 }
39
40 /* Return the seals set on FD. */
41 static int
get_seals(int fd)42 get_seals (int fd)
43 {
44 int flags = fcntl (fd, F_GET_SEALS);
45 TEST_VERIFY (flags >= 0);
46 return flags;
47 }
48
49 /* Return true if the F_SEAL_SEAL flag is set on the descriptor. */
50 static bool
is_sealed(int fd)51 is_sealed (int fd)
52 {
53 return get_seals (fd) & F_SEAL_SEAL;
54 }
55
56 static int
do_test(void)57 do_test (void)
58 {
59 /* Initialized by the first call to memfd_create to 0 (memfd_create
60 unsupported) or 1 (memfd_create is implemented in the kernel).
61 Subsequent iterations check that the success/failure state is
62 consistent. */
63 int supported = -1;
64
65 for (int do_cloexec = 0; do_cloexec < 2; ++do_cloexec)
66 for (int do_sealing = 0; do_sealing < 2; ++do_sealing)
67 {
68 int flags = 0;
69 if (do_cloexec)
70 flags |= MFD_CLOEXEC;
71 if (do_sealing)
72 flags |= MFD_ALLOW_SEALING;
73 if (test_verbose > 0)
74 printf ("info: memfd_create with flags=0x%x\n", flags);
75 int fd = memfd_create ("tst-memfd_create", flags);
76 if (fd < 0)
77 {
78 if (errno == ENOSYS)
79 {
80 if (supported < 0)
81 {
82 printf ("warning: memfd_create is unsupported\n");
83 supported = 0;
84 continue;
85 }
86 TEST_VERIFY (supported == 0);
87 continue;
88 }
89 else
90 FAIL_EXIT1 ("memfd_create: %m");
91 }
92 if (supported < 0)
93 supported = 1;
94 TEST_VERIFY (supported > 0);
95
96 char *fd_path = xasprintf ("/proc/self/fd/%d", fd);
97 char *link = xreadlink (fd_path);
98 if (test_verbose > 0)
99 printf ("info: memfd link: %s\n", link);
100 TEST_VERIFY (strcmp (link, "memfd:tst-memfd_create (deleted)"));
101 TEST_VERIFY (is_cloexec (fd) == do_cloexec);
102 TEST_VERIFY (is_sealed (fd) == !do_sealing);
103 if (do_sealing)
104 {
105 TEST_VERIFY (fcntl (fd, F_ADD_SEALS, F_SEAL_WRITE) == 0);
106 TEST_VERIFY (!is_sealed (fd));
107 TEST_VERIFY (get_seals (fd) & F_SEAL_WRITE);
108 TEST_VERIFY (fcntl (fd, F_ADD_SEALS, F_SEAL_SEAL) == 0);
109 TEST_VERIFY (is_sealed (fd));
110 }
111 xclose (fd);
112 free (fd_path);
113 free (link);
114 }
115
116 if (supported == 0)
117 return EXIT_UNSUPPORTED;
118 return 0;
119 }
120
121 #include <support/test-driver.c>
122