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 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 else if (npgs == 1) { 99 errno = ENOSYS; 100 goto clean; 101 } 102 103 if ((flags & MFD_HUGE_MASK) == 0) { 104 pgidx = 1; 105 } else { 106 pgsize = 1UL << ((flags & MFD_HUGE_MASK) >> MFD_HUGE_SHIFT); 107 for (pgidx = 1; pgidx < npgs; pgidx++) { 108 if (pgsize == pgs[pgidx]) 109 break; 110 } 111 if (pgidx == npgs) { 112 errno = EOPNOTSUPP; 113 goto clean; 114 } 115 } 116 117 memset(&slc, 0, sizeof(slc)); 118 slc.psind = pgidx; 119 slc.alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT; 120 error = ioctl(fd, FIOSSHMLPGCNF, &slc); 121 if (error == -1) 122 goto clean; 123 return (fd); 124 125 clean: 126 saved_errno = errno; 127 close(fd); 128 errno = saved_errno; 129 return (-1); 130 } 131