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 */
50int
51memfd_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
116clean:
117	saved_errno = errno;
118	close(fd);
119	errno = saved_errno;
120	return (-1);
121}
122