1 files changed, 121 insertions, 0 deletions
diff --git a/lib/libc/gen/memfd_create.c b/lib/libc/gen/memfd_create.c
new file mode 100644
index 000000000000..78131f46d7b1
--- /dev/null
+++ b/lib/libc/gen/memfd_create.c
@@ -0,0 +1,121 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2019 Kyle Evans <kevans@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice(s), this list of conditions and the following disclaimer as
+ *    the first lines of this file unmodified other than the possible
+ *    addition of one or more copyright notices.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice(s), this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/param.h>
+#include <sys/filio.h>
+#include <sys/mman.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "libc_private.h"
+
+#define	MEMFD_NAME_PREFIX	"memfd:"
+
+/*
+ * The path argument is passed to the kernel, but the kernel doesn't currently
+ * do anything with it.  Linux exposes it in linprocfs for debugging purposes
+ * only, but our kernel currently will not do the same.
+ */
+int
+memfd_create(const char *name, unsigned int flags)
+{
+	char memfd_name[NAME_MAX + 1];
+	size_t pgs[MAXPAGESIZES];
+	size_t namelen, pgsize;
+	struct shm_largepage_conf slc;
+	int error, fd, npgs, oflags, pgidx, saved_errno, shmflags;
+
+	if (name == NULL) {
+		errno = EBADF;
+		return (-1);
+	}
+	namelen = strlen(name);
+	if (namelen + sizeof(MEMFD_NAME_PREFIX) - 1 > NAME_MAX) {
+		errno = EINVAL;
+		return (-1);
+	}
+	if ((flags & ~(MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB |
+	    MFD_HUGE_MASK)) != 0) {
+		errno = EINVAL;
+		return (-1);
+	}
+	/* Size specified but no HUGETLB. */
+	if ((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0) {
+		errno = EINVAL;
+		return (-1);
+	}
+
+	/* We've already validated that we're sufficiently sized. */
+	snprintf(memfd_name, NAME_MAX + 1, "%s%s", MEMFD_NAME_PREFIX, name);
+	oflags = O_RDWR;
+	shmflags = 0;
+	if ((flags & MFD_CLOEXEC) != 0)
+		oflags |= O_CLOEXEC;
+	if ((flags & MFD_ALLOW_SEALING) != 0)
+		shmflags |= SHM_ALLOW_SEALING;
+	if ((flags & MFD_HUGETLB) != 0)
+		shmflags |= SHM_LARGEPAGE;
+	else
+		shmflags |= SHM_GROW_ON_WRITE;
+	fd = __sys_shm_open2(SHM_ANON, oflags, 0, shmflags, memfd_name);
+	if (fd == -1 || (flags & MFD_HUGETLB) == 0)
+		return (fd);
+
+	npgs = getpagesizes(pgs, nitems(pgs));
+	if (npgs == -1)
+		goto clean;
+	pgsize = (size_t)1 << ((flags & MFD_HUGE_MASK) >> MFD_HUGE_SHIFT);
+	for (pgidx = 0; pgidx < npgs; pgidx++) {
+		if (pgsize == pgs[pgidx])
+			break;
+	}
+	if (pgidx == npgs) {
+		errno = EOPNOTSUPP;
+		goto clean;
+	}
+
+	memset(&slc, 0, sizeof(slc));
+	slc.psind = pgidx;
+	slc.alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
+	error = ioctl(fd, FIOSSHMLPGCNF, &slc);
+	if (error == -1)
+		goto clean;
+	return (fd);
+
+clean:
+	saved_errno = errno;
+	close(fd);
+	errno = saved_errno;
+	return (-1);
+}