2 * Copyright (c) 2019 Kyle Evans <kevans@FreeBSD.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice(s), this list of conditions and the following disclaimer as
10 * the first lines of this file unmodified other than the possible
11 * addition of one or more copyright notices.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice(s), this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
21 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
24 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
25 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
26 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
33 #include <sys/types.h>
35 #include <sys/syscall.h>
44 #include "libc_private.h"
46 __weak_reference(shm_open, _shm_open);
47 __weak_reference(shm_open, __sys_shm_open);
49 #define SHM_OPEN2_OSREL 1300048
51 #define MEMFD_NAME_PREFIX "memfd:"
54 shm_open(const char *path, int flags, mode_t mode)
57 if (__getosreldate() >= SHM_OPEN2_OSREL)
58 return (__sys_shm_open2(path, flags | O_CLOEXEC, mode, 0,
62 * Fallback to shm_open(2) on older kernels. The kernel will enforce
63 * O_CLOEXEC in this interface, unlike the newer shm_open2 which does
64 * not enforce it. The newer interface allows memfd_create(), for
65 * instance, to not have CLOEXEC on the returned fd.
67 return (syscall(SYS_freebsd12_shm_open, path, flags, mode));
71 * The path argument is passed to the kernel, but the kernel doesn't currently
72 * do anything with it. Linux exposes it in linprocfs for debugging purposes
73 * only, but our kernel currently will not do the same.
76 memfd_create(const char *name, unsigned int flags)
78 char memfd_name[NAME_MAX + 1];
84 namelen = strlen(name);
85 if (namelen + sizeof(MEMFD_NAME_PREFIX) - 1 > NAME_MAX)
87 if ((flags & ~(MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB |
90 /* HUGETLB set with no size specified. */
91 if ((flags & MFD_HUGETLB) != 0 && (flags & MFD_HUGE_MASK) == 0)
93 /* Size specified but no HUGETLB. */
94 if ((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0)
96 /* We don't actually support HUGETLB. */
97 if ((flags & MFD_HUGETLB) != 0)
100 /* We've already validated that we're sufficiently sized. */
101 snprintf(memfd_name, NAME_MAX + 1, "%s%s", MEMFD_NAME_PREFIX, name);
104 if ((flags & MFD_CLOEXEC) != 0)
106 if ((flags & MFD_ALLOW_SEALING) != 0)
107 shmflags |= SHM_ALLOW_SEALING;
108 return (__sys_shm_open2(SHM_ANON, oflags, 0, shmflags, memfd_name));