1 /* 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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/cdefs.h> 32 __FBSDID("$FreeBSD$"); 33 34 #include <sys/types.h> 35 #include <sys/mman.h> 36 #include <sys/syscall.h> 37 38 #include <errno.h> 39 #include <fcntl.h> 40 #include <limits.h> 41 #include <unistd.h> 42 #include <stdio.h> 43 #include <string.h> 44 45 #include "libc_private.h" 46 47 __weak_reference(shm_open, _shm_open); 48 __weak_reference(shm_open, __sys_shm_open); 49 50 #define SHM_OPEN2_OSREL 1300048 51 52 #define MEMFD_NAME_PREFIX "memfd:" 53 54 int 55 shm_open(const char *path, int flags, mode_t mode) 56 { 57 58 if (__getosreldate() >= SHM_OPEN2_OSREL) 59 return (__sys_shm_open2(path, flags | O_CLOEXEC, mode, 0, 60 NULL)); 61 62 /* 63 * Fallback to shm_open(2) on older kernels. The kernel will enforce 64 * O_CLOEXEC in this interface, unlike the newer shm_open2 which does 65 * not enforce it. The newer interface allows memfd_create(), for 66 * instance, to not have CLOEXEC on the returned fd. 67 */ 68 return (syscall(SYS_freebsd12_shm_open, path, flags, mode)); 69 } 70 71 /* 72 * The path argument is passed to the kernel, but the kernel doesn't currently 73 * do anything with it. Linux exposes it in linprocfs for debugging purposes 74 * only, but our kernel currently will not do the same. 75 */ 76 int 77 memfd_create(const char *name, unsigned int flags) 78 { 79 char memfd_name[NAME_MAX + 1]; 80 size_t namelen; 81 int oflags, shmflags; 82 83 if (name == NULL) 84 return (EBADF); 85 namelen = strlen(name); 86 if (namelen + sizeof(MEMFD_NAME_PREFIX) - 1 > NAME_MAX) 87 return (EINVAL); 88 if ((flags & ~(MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB | 89 MFD_HUGE_MASK)) != 0) 90 return (EINVAL); 91 /* Size specified but no HUGETLB. */ 92 if ((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0) 93 return (EINVAL); 94 /* We don't actually support HUGETLB. */ 95 if ((flags & MFD_HUGETLB) != 0) 96 return (ENOSYS); 97 98 /* We've already validated that we're sufficiently sized. */ 99 snprintf(memfd_name, NAME_MAX + 1, "%s%s", MEMFD_NAME_PREFIX, name); 100 oflags = O_RDWR; 101 shmflags = 0; 102 if ((flags & MFD_CLOEXEC) != 0) 103 oflags |= O_CLOEXEC; 104 if ((flags & MFD_ALLOW_SEALING) != 0) 105 shmflags |= SHM_ALLOW_SEALING; 106 return (__sys_shm_open2(SHM_ANON, oflags, 0, shmflags, memfd_name)); 107 } 108