423a033ba7
memfd_create fds will no longer require an ftruncate(2) to set the size; they'll grow (to the extent that it's possible) upon write(2)-like syscalls. Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D25502
94 lines
3.1 KiB
C
94 lines
3.1 KiB
C
/*
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2019 Kyle Evans <kevans@FreeBSD.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice(s), this list of conditions and the following disclaimer as
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* the first lines of this file unmodified other than the possible
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* addition of one or more copyright notices.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice(s), this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdio.h>
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#include <string.h>
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#include "libc_private.h"
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__weak_reference(shm_open, _shm_open);
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__weak_reference(shm_open, __sys_shm_open);
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#define MEMFD_NAME_PREFIX "memfd:"
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int
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shm_open(const char *path, int flags, mode_t mode)
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{
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return (__sys_shm_open2(path, flags | O_CLOEXEC, mode, 0, NULL));
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}
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/*
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* The path argument is passed to the kernel, but the kernel doesn't currently
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* do anything with it. Linux exposes it in linprocfs for debugging purposes
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* only, but our kernel currently will not do the same.
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*/
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int
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memfd_create(const char *name, unsigned int flags)
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{
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char memfd_name[NAME_MAX + 1];
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size_t namelen;
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int oflags, shmflags;
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if (name == NULL)
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return (EBADF);
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namelen = strlen(name);
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if (namelen + sizeof(MEMFD_NAME_PREFIX) - 1 > NAME_MAX)
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return (EINVAL);
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if ((flags & ~(MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB |
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MFD_HUGE_MASK)) != 0)
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return (EINVAL);
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/* Size specified but no HUGETLB. */
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if ((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0)
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return (EINVAL);
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/* We don't actually support HUGETLB. */
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if ((flags & MFD_HUGETLB) != 0)
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return (ENOSYS);
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/* We've already validated that we're sufficiently sized. */
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snprintf(memfd_name, NAME_MAX + 1, "%s%s", MEMFD_NAME_PREFIX, name);
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oflags = O_RDWR;
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shmflags = SHM_GROW_ON_WRITE;
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if ((flags & MFD_CLOEXEC) != 0)
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oflags |= O_CLOEXEC;
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if ((flags & MFD_ALLOW_SEALING) != 0)
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shmflags |= SHM_ALLOW_SEALING;
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return (__sys_shm_open2(SHM_ANON, oflags, 0, shmflags, memfd_name));
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}
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