d12d651f86
Make it work, but change the interface to be safe for non-root users. In particular, right now interface only works for the tables which can be minimally parsed by kernel to determine the table size. Then, userspace can query the table size, after that it provides a buffer of needed size and kernel copies out just table to userspace. Main advantage is that user no longer need to be able to read /dev/mem, the disadvantage is the need to have minimal parsers aware of the table types. Right now the parsers are implemented for ESRT and PROP tables. Future extension of the present interface might be a return of only the table physical address, in case kernel does not have suitable parser yet. Then, a privileged user could read the table from /dev/mem. This extension, which logically equivalent to the old (non-worked) EFIIOC_GET_TABLE variant, is not implemented until needed. Submitted by: Pavel Balaev <pavel.balaev@3mdeb.com> MFC after: 2 weeks Differential revision: https://reviews.freebsd.org/D30104
165 lines
4.5 KiB
Groff
165 lines
4.5 KiB
Groff
.\"-
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.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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.\"
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.\" Copyright (c) 2018 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, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 18, 2021
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.Dt EFIDEV 4
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.Os
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.Sh NAME
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.Nm efidev ,
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.Nm efirtc
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.Nd user-mode access to UEFI runtime services
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.Sh SYNOPSIS
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To compile this driver into the kernel, place the following lines in your
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kernel configuration file:
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.Bd -ragged -offset -indent
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.Cd "options EFIRT"
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.Ed
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.Pp
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Alternatively, to load the driver as a module at boot time, place the following
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line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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efirt_load="YES"
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.Ed
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.Pp
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The driver may be disabled by setting the
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.Xr loader 8
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tunable
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.Va efi.rt.disabled
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to
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.Dq Li 1 .
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.Sh DESCRIPTION
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The
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.Nm
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device provides user-mode access to UEFI runtime services.
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.Nm
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also includes a driver to provide a time-of-day clock using the UEFI
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real time clock (RTC).
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However, the RTC may not always be available, based on the UEFI firmware.
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If the RTC is not available, it will not be registered as a time-of-day clock
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and the time related ioctls below will not be functional.
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.Pp
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.Nm
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provides the following ioctls defined in
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.In sys/efiio.h
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with supplemental structures and constants defined in
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.In sys/efi.h :
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.Bl -tag -width indent
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.It Dv EFIIOC_GET_TABLE Pq Vt "struct efi_get_table_ioc"
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Copy the UEFI table specified by the
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.Va uuid
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field of the
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.Vt struct efi_get_table_ioc
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into the
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.Va buf
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field.
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The memory size for the buf field can be queried by passing
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.Dv NULL
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pointer as a buf value.
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The required size will be stored in the
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.Va table_len
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field.
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The size of the allocated memory must be specified in the
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.Va buf_len
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field.
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.Bd -literal -offset indent
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struct efi_get_table_ioc {
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void *buf;
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struct uuid uuid;
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size_t table_len;
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size_t buf_len;
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};
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.Ed
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.It Dv EFIIOC_GET_TIME Pq Vt "struct efi_tm"
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Get the time from the RTC, if the RTC is available.
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The
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.Vt struct efi_tm
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passed is populated with the current time, unless an error occurs.
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.Bd -literal -offset indent
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struct efi_tm {
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uint16_t tm_year;
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uint8_t tm_mon
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uint8_t tm_mday
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uint8_t tm_hour;
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uint8_t tm_min;
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uint8_t tm_sec;
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uint8_t __pad1;
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uint32_t tm_nsec;
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int16_t tm_tz;
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uint8_t tm_dst;
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uint8_t __pad2;
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};
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.Ed
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.It Dv EFIIOC_SET_TIME Pq Vt "struct efi_tm"
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Sets the time stored by the RTC, if the RTC is available.
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.It Dv EFIIOC_VAR_GET Pq Vt "struct efi_var_ioc"
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Gets data from the variable described by the vendor and name fields of the
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.Vt struct efi_var_ioc
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into the
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.Fa data
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field.
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.Dv EFIIOC_VAR_GET Pq Vt "struct efi_var_ioc"
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will also populate the
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.Fa attrib
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field.
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.Bd -literal
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struct efi_var_ioc {
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efi_char *name;
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size_t namesize;
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struct uuid vendor;
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uint32_t attrib;
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void *data;
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size_t datasize;
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};
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.Ed
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.It Dv EFIIOC_VAR_NEXT Pq Vt "struct efi_var_ioc"
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Used for enumerating all UEFI variables.
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The initial call should use an empty string for the name attribute.
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Subsequent calls should supply the vendor uuid and name of the last variable
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returned.
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.It Dv EFIIOC_VAR_SET Pq Vt "struct efi_var_ioc"
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Sets data and attributes for the variable described by the name and vendor in
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the
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.Vt struct efi_var_ioc .
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.El
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.Sh FILES
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.Bl -tag -width /dev/efi
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.It Pa /dev/efi
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.El
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.Sh SEE ALSO
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.Xr efivar 3 ,
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.Xr efirt 9
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.Sh HISTORY
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A
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.Nm
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device first appeared in
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.Fx 11.1 .
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.Sh BUGS
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.Nm
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is currently only available on amd64 and arm64.
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