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authorjmcneill <jmcneill@NetBSD.org>2021-10-10 13:03:08 +0000
committerjmcneill <jmcneill@NetBSD.org>2021-10-10 13:03:08 +0000
commit25ff60a647236a2f67fc08ecac96a14fecffd6f1 (patch)
tree9e294fa34b95c1c6d543d5ee9b53c056ea3aff66 /sys/dev
parentbb18b00d04ee512d526a620a8e16276e464d6241 (diff)
efi: Add /dev/efi character device
Introduce a /dev/efi character device that provides a means for accessing UEFI RT variable services from userland. Compatible with the FreeBSD ioctl interface for ease of porting their libefivar and associated tools. The ioctl interface is defined in sys/efiio.h. To enable support for this on an arch, the kernel needs `pseudo-device efi` and the MD EFI implementation needs to register its backend by calling efi_ops_register(). This commit includes an implementation for Arm.
Diffstat (limited to 'sys/dev')
-rw-r--r--sys/dev/efi.c306
-rw-r--r--sys/dev/efivar.h46
-rw-r--r--sys/dev/files.dev5
3 files changed, 356 insertions, 1 deletions
diff --git a/sys/dev/efi.c b/sys/dev/efi.c
new file mode 100644
index 00000000000..3d5affab0fa
--- /dev/null
+++ b/sys/dev/efi.c
@@ -0,0 +1,306 @@
+/* $NetBSD: efi.c,v 1.1 2021/10/10 13:03:09 jmcneill Exp $ */
+
+/*-
+ * Copyright (c) 2021 Jared McNeill <jmcneill@invisible.ca>
+ * All rights reserved.
+ *
+ * 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, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, 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 AUTHOR ``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 AUTHOR 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.
+ */
+
+/*
+ * This pseudo-driver implements a /dev/efi character device that provides
+ * ioctls for using UEFI runtime time and variable services.
+ */
+
+#include <sys/cdefs.h>
+__KERNEL_RCSID(0, "$NetBSD: efi.c,v 1.1 2021/10/10 13:03:09 jmcneill Exp $");
+
+#include <sys/param.h>
+#include <sys/conf.h>
+#include <sys/kmem.h>
+#include <sys/atomic.h>
+#include <sys/efiio.h>
+
+#include <dev/efivar.h>
+
+#ifdef _LP64
+#define EFIERR(x) (0x8000000000000000 | x)
+#else
+#define EFIERR(x) (0x80000000 | x)
+#endif
+
+#define EFI_SUCCESS 0
+#define EFI_INVALID_PARAMETER EFIERR(2)
+#define EFI_UNSUPPORTED EFIERR(3)
+#define EFI_BUFFER_TOO_SMALL EFIERR(5)
+#define EFI_DEVICE_ERROR EFIERR(7)
+#define EFI_WRITE_PROTECTED EFIERR(8)
+#define EFI_OUT_OF_RESOURCES EFIERR(9)
+#define EFI_NOT_FOUND EFIERR(14)
+#define EFI_SECURITY_VIOLATION EFIERR(26)
+
+#include "ioconf.h"
+
+/*
+ * Maximum length of an EFI variable name. The UEFI spec doesn't specify a
+ * constraint, but we want to limit the size to act as a guard rail against
+ * allocating too much kernel memory.
+ */
+#define EFI_VARNAME_MAXLENGTH EFI_PAGE_SIZE
+
+/*
+ * Pointer to arch specific EFI backend.
+ */
+static const struct efi_ops *efi_ops = NULL;
+
+/*
+ * Only allow one user of /dev/efi at a time. Even though the MD EFI backends
+ * should serialize individual UEFI RT calls, the UEFI specification says
+ * that a SetVariable() call between calls to GetNextVariableName() may
+ * produce unpredictable results, and we want to avoid this.
+ */
+static u_int efi_isopen = 0;
+
+static dev_type_open(efi_open);
+static dev_type_close(efi_close);
+static dev_type_ioctl(efi_ioctl);
+
+const struct cdevsw efi_cdevsw = {
+ .d_open = efi_open,
+ .d_close = efi_close,
+ .d_ioctl = efi_ioctl,
+ .d_read = noread,
+ .d_write = nowrite,
+ .d_stop = nostop,
+ .d_tty = notty,
+ .d_poll = nopoll,
+ .d_mmap = nommap,
+ .d_kqfilter = nokqfilter,
+ .d_discard = nodiscard,
+ .d_flag = D_OTHER | D_MPSAFE,
+};
+
+static int
+efi_open(dev_t dev, int flags, int type, struct lwp *l)
+{
+ if (efi_ops == NULL) {
+ return ENXIO;
+ }
+ if (atomic_cas_uint(&efi_isopen, 0, 1) == 1) {
+ return EBUSY;
+ }
+ return 0;
+}
+
+static int
+efi_close(dev_t dev, int flags, int type, struct lwp *l)
+{
+ KASSERT(efi_isopen);
+ atomic_swap_uint(&efi_isopen, 0);
+ return 0;
+}
+
+static int
+efi_status_to_error(efi_status status)
+{
+ switch (status) {
+ case EFI_SUCCESS:
+ return 0;
+ case EFI_INVALID_PARAMETER:
+ return EINVAL;
+ case EFI_UNSUPPORTED:
+ return EOPNOTSUPP;
+ case EFI_BUFFER_TOO_SMALL:
+ return ERANGE;
+ case EFI_DEVICE_ERROR:
+ return EIO;
+ case EFI_WRITE_PROTECTED:
+ return EROFS;
+ case EFI_OUT_OF_RESOURCES:
+ return ENOMEM;
+ case EFI_NOT_FOUND:
+ return ENOENT;
+ case EFI_SECURITY_VIOLATION:
+ return EACCES;
+ default:
+ return EIO;
+ }
+}
+
+static int
+efi_ioctl_var_get(struct efi_var_ioc *var)
+{
+ uint16_t *namebuf;
+ void *databuf = NULL;
+ efi_status status;
+ int error;
+
+ if (var->name == NULL || var->namesize == 0 ||
+ (var->data != NULL && var->datasize == 0)) {
+ return EINVAL;
+ }
+ if (var->namesize > EFI_VARNAME_MAXLENGTH) {
+ return ENOMEM;
+ }
+
+ namebuf = kmem_alloc(var->namesize, KM_SLEEP);
+ error = copyin(var->name, namebuf, var->namesize);
+ if (error != 0) {
+ goto done;
+ }
+ if (namebuf[var->namesize / 2 - 1] != '\0') {
+ error = EINVAL;
+ goto done;
+ }
+ if (var->datasize != 0) {
+ databuf = kmem_alloc(var->datasize, KM_SLEEP);
+ error = copyin(var->data, databuf, var->datasize);
+ if (error != 0) {
+ goto done;
+ }
+ }
+
+ status = efi_ops->efi_getvar(namebuf, &var->vendor, &var->attrib,
+ &var->datasize, databuf);
+ if (status != EFI_SUCCESS && status != EFI_BUFFER_TOO_SMALL) {
+ error = efi_status_to_error(status);
+ goto done;
+ }
+ if (status == EFI_SUCCESS && databuf != NULL) {
+ error = copyout(databuf, var->data, var->datasize);
+ } else {
+ var->data = NULL;
+ }
+
+done:
+ kmem_free(namebuf, var->namesize);
+ if (databuf != NULL) {
+ kmem_free(databuf, var->datasize);
+ }
+ return error;
+}
+
+static int
+efi_ioctl_var_next(struct efi_var_ioc *var)
+{
+ efi_status status;
+ uint16_t *namebuf;
+ int error;
+
+ if (var->name == NULL || var->namesize == 0) {
+ return EINVAL;
+ }
+ if (var->namesize > EFI_VARNAME_MAXLENGTH) {
+ return ENOMEM;
+ }
+
+ namebuf = kmem_alloc(var->namesize, KM_SLEEP);
+ error = copyin(var->name, namebuf, var->namesize);
+ if (error != 0) {
+ goto done;
+ }
+
+ status = efi_ops->efi_nextvar(&var->namesize, namebuf, &var->vendor);
+ if (status != EFI_SUCCESS && status != EFI_BUFFER_TOO_SMALL) {
+ error = efi_status_to_error(status);
+ goto done;
+ }
+ if (status == EFI_SUCCESS) {
+ error = copyout(namebuf, var->name, var->namesize);
+ } else {
+ var->name = NULL;
+ }
+
+done:
+ kmem_free(namebuf, var->namesize);
+ return error;
+}
+
+static int
+efi_ioctl_var_set(struct efi_var_ioc *var)
+{
+ efi_status status;
+ uint16_t *namebuf;
+ uint16_t *databuf = NULL;
+ int error;
+
+ if (var->name == NULL || var->namesize == 0) {
+ return EINVAL;
+ }
+
+ namebuf = kmem_alloc(var->namesize, KM_SLEEP);
+ error = copyin(var->name, namebuf, var->namesize);
+ if (error != 0) {
+ goto done;
+ }
+ if (namebuf[var->namesize / 2 - 1] != '\0') {
+ error = EINVAL;
+ goto done;
+ }
+ if (var->datasize != 0) {
+ databuf = kmem_alloc(var->datasize, KM_SLEEP);
+ error = copyin(var->data, databuf, var->datasize);
+ if (error != 0) {
+ goto done;
+ }
+ }
+
+ status = efi_ops->efi_setvar(namebuf, &var->vendor, var->attrib,
+ var->datasize, databuf);
+ error = efi_status_to_error(status);
+
+done:
+ kmem_free(namebuf, var->namesize);
+ if (databuf != NULL) {
+ kmem_free(databuf, var->datasize);
+ }
+ return error;
+}
+
+static int
+efi_ioctl(dev_t dev, u_long cmd, void *data, int flags, struct lwp *l)
+{
+ KASSERT(efi_ops != NULL);
+
+ switch (cmd) {
+ case EFIIOC_VAR_GET:
+ return efi_ioctl_var_get(data);
+ case EFIIOC_VAR_NEXT:
+ return efi_ioctl_var_next(data);
+ case EFIIOC_VAR_SET:
+ return efi_ioctl_var_set(data);
+ }
+
+ return ENOTTY;
+}
+
+void
+efi_register_ops(const struct efi_ops *ops)
+{
+ KASSERT(efi_ops == NULL);
+ efi_ops = ops;
+}
+
+void
+efiattach(int count)
+{
+}
diff --git a/sys/dev/efivar.h b/sys/dev/efivar.h
new file mode 100644
index 00000000000..21d6d61fd26
--- /dev/null
+++ b/sys/dev/efivar.h
@@ -0,0 +1,46 @@
+/* $NetBSD: efivar.h,v 1.1 2021/10/10 13:03:09 jmcneill Exp $ */
+
+/*-
+ * Copyright (c) 2021 Jared McNeill <jmcneill@invisible.ca>
+ * All rights reserved.
+ *
+ * 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, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, 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 AUTHOR ``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 AUTHOR 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.
+ */
+
+#ifndef _DEV_EFIVAR_H
+#define _DEV_EFIVAR_H
+
+#include <machine/efi.h>
+
+struct efi_ops {
+ efi_status (*efi_gettime)(struct efi_tm *, struct efi_tmcap *);
+ efi_status (*efi_settime)(struct efi_tm *);
+ efi_status (*efi_getvar)(uint16_t *, struct uuid *, uint32_t *,
+ u_long *, void *);
+ efi_status (*efi_setvar)(uint16_t *, struct uuid *, uint32_t,
+ u_long, void *);
+ efi_status (*efi_nextvar)(u_long *, uint16_t *, struct uuid *);
+};
+
+void efi_register_ops(const struct efi_ops *);
+
+#endif /* !_DEV_EFIVAR_H */
diff --git a/sys/dev/files.dev b/sys/dev/files.dev
index 5b5c00eb413..902363c0d72 100644
--- a/sys/dev/files.dev
+++ b/sys/dev/files.dev
@@ -1,4 +1,4 @@
-# $NetBSD: files.dev,v 1.7 2021/07/21 23:16:09 jmcneill Exp $
+# $NetBSD: files.dev,v 1.8 2021/10/10 13:03:09 jmcneill Exp $
file dev/bio.c bio needs-flag
file dev/ccd.c ccd
@@ -27,3 +27,6 @@ file dev/video.c video needs-flag
file dev/vnd.c vnd
file dev/ipmi.c ipmi needs-flag
file dev/smbios.c smbios
+
+defpseudo efi
+file dev/efi.c efi needs-flag