1 /*
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2019 Kyle Evans <kevans@FreeBSD.org>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice(s), this list of conditions and the following disclaimer as
11 * the first lines of this file unmodified other than the possible
12 * addition of one or more copyright notices.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice(s), this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
19 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
25 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
26 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
27 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
28 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include <sys/param.h>
32 #include <sys/filio.h>
33 #include <sys/mman.h>
34
35 #include <errno.h>
36 #include <fcntl.h>
37 #include <stdio.h>
38 #include <string.h>
39 #include <unistd.h>
40
41 #include "libc_private.h"
42
43 #define MEMFD_NAME_PREFIX "memfd:"
44
45 /*
46 * The path argument is passed to the kernel, but the kernel doesn't currently
47 * do anything with it. Linux exposes it in linprocfs for debugging purposes
48 * only, but our kernel currently will not do the same.
49 */
50 int
memfd_create(const char * name,unsigned int flags)51 memfd_create(const char *name, unsigned int flags)
52 {
53 char memfd_name[NAME_MAX + 1];
54 size_t pgs[MAXPAGESIZES];
55 size_t namelen, pgsize;
56 struct shm_largepage_conf slc;
57 int error, fd, npgs, oflags, pgidx, saved_errno, shmflags;
58
59 if (name == NULL) {
60 errno = EBADF;
61 return (-1);
62 }
63 namelen = strlen(name);
64 if (namelen + sizeof(MEMFD_NAME_PREFIX) - 1 > NAME_MAX) {
65 errno = EINVAL;
66 return (-1);
67 }
68 if ((flags & ~(MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB |
69 MFD_HUGE_MASK)) != 0) {
70 errno = EINVAL;
71 return (-1);
72 }
73 /* Size specified but no HUGETLB. */
74 if ((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0) {
75 errno = EINVAL;
76 return (-1);
77 }
78
79 /* We've already validated that we're sufficiently sized. */
80 snprintf(memfd_name, NAME_MAX + 1, "%s%s", MEMFD_NAME_PREFIX, name);
81 oflags = O_RDWR;
82 shmflags = 0;
83 if ((flags & MFD_CLOEXEC) != 0)
84 oflags |= O_CLOEXEC;
85 if ((flags & MFD_ALLOW_SEALING) != 0)
86 shmflags |= SHM_ALLOW_SEALING;
87 if ((flags & MFD_HUGETLB) != 0)
88 shmflags |= SHM_LARGEPAGE;
89 else
90 shmflags |= SHM_GROW_ON_WRITE;
91 fd = __sys_shm_open2(SHM_ANON, oflags, 0, shmflags, memfd_name);
92 if (fd == -1 || (flags & MFD_HUGETLB) == 0)
93 return (fd);
94
95 npgs = getpagesizes(pgs, nitems(pgs));
96 if (npgs == -1)
97 goto clean;
98 pgsize = (size_t)1 << ((flags & MFD_HUGE_MASK) >> MFD_HUGE_SHIFT);
99 for (pgidx = 0; pgidx < npgs; pgidx++) {
100 if (pgsize == pgs[pgidx])
101 break;
102 }
103 if (pgidx == npgs) {
104 errno = EOPNOTSUPP;
105 goto clean;
106 }
107
108 memset(&slc, 0, sizeof(slc));
109 slc.psind = pgidx;
110 slc.alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
111 error = ioctl(fd, FIOSSHMLPGCNF, &slc);
112 if (error == -1)
113 goto clean;
114 return (fd);
115
116 clean:
117 saved_errno = errno;
118 close(fd);
119 errno = saved_errno;
120 return (-1);
121 }
122