efi: efibc: Guard against allocation failure

There is a single kmalloc in this driver, and it's not currently
guarded against allocation failure. Do it here by just bailing-out
the reboot handler, in case this tentative allocation fails.

Fixes: 416581e48679 ("efi: efibc: avoid efivar API for setting variables")
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

efi: efibc: avoid efivar API for setting variables

Avoid abusing the efivar API by passing locally instantiated
efivar_entry structs into efivar_set_entry_safe(), rather than using the
API as intended. Instead, just call efi.set_variable() directly.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

efi: efibc: check for efivars write capability

Branden reports that commit

f88814cc2578c1 ("efi/efivars: Expose RT service availability via efivars abstraction")

regresses UEFI platforms that implement GetVariable but not SetVariable
when booting kernels that have EFIBC (bootloader control) enabled.

The reason is that EFIBC is a user of the efivars abstraction, which was
updated to permit users that rely only on the read capability, but not on
the write capability. EFIBC is in the latter category, so it has to check
explicitly whether efivars supports writes.

Fixes: f88814cc2578c1 ("efi/efivars: Expose RT service availability via efivars abstraction")
Tested-by: Branden Sherrell <sherrellbc@gmail.com>
Link: https://lore.kernel.org/linux-efi/AE217103-C96F-4AFC-8417-83EC11962004@gmail.com/
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

efibc: Replace variable set function in notifier call

Replace the variable set function from "efivar_entry_set" to
"efivar_entry_set_safe" in efibc panic notifier.
In safe function parameter "block" will set to false
and will call "efivar_entry_set_nonblocking"to set efi variables.
efivar_entry_set_nonblocking is guaranteed to
not block and is suitable for calling from crash/panic handlers.
In UEFI android platform, when warm reset happens,
with this change, efibc will not block the reboot process.
Otherwise, set variable will call queue work and send to other offlined
cpus then cause another panic, finally will cause reboot failure.

Signed-off-by: Tian Baofeng <baofeng.tian@intel.com>
Signed-off-by: Luo XinanX <xinanx.luo@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

efi: Replace GPL license boilerplate with SPDX headers

Replace all GPL license blurbs with an equivalent SPDX header (most
files are GPLv2, some are GPLv2+). While at it, drop some outdated
header changelogs as well.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Jeffrey Hugo <jhugo@codeaurora.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20190202094119.13230-7-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

efibc: Report more information in the error messages

Report the name of the EFI variable if the value size is too large,
or if efibc_set_variable() fails to allocate the 'struct efivar_entry'
object.

If efibc_set_variable() fails because the 'size' value is too
large, it also reports this value in the error message.

Reported-by: Robert Elliott <elliott@hpe.com>
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1466839230-12781-2-git-send-email-matt@codeblueprint.co.uk
[ Minor readability edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

efibc: Fix excessive stack footprint warning

GCC complains about a newly added file for the EFI Bootloader Control:

drivers/firmware/efi/efibc.c: In function 'efibc_set_variable':
drivers/firmware/efi/efibc.c:53:1: error: the frame size of 2272 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

The problem is the declaration of a local variable of type struct
efivar_entry, which is by itself larger than the warning limit of 1024
bytes.

Use dynamic memory allocation instead of stack memory for the entry
object.

This patch also fixes a potential buffer overflow.

Reported-by: Ingo Molnar <mingo@kernel.org>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
[ Updated changelog to include GCC error ]
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1462570771-13324-3-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>

efibc: Add EFI Bootloader Control module

This module installs a reboot callback, such that if reboot() is invoked
with a string argument NNN, "NNN" is copied to the "LoaderEntryOneShot"
EFI variable, to be read by the bootloader.

If the string matches one of the boot labels defined in its configuration,
the bootloader will boot once to that label. The "LoaderEntryRebootReason"
EFI variable is set with the reboot reason: "reboot", "shutdown".

The bootloader reads this reboot reason and takes particular action
according to its policy.

There are reboot implementations that do "reboot <reason>", such as
Android's reboot command and Upstart's reboot replacement, which pass
the reason as an argument to the reboot syscall. There is no
platform-agnostic way how those could be modified to pass the reason
to the bootloader, regardless of platform or bootloader.

Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stefan Stanacar <stefan.stanacar@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1461614832-17633-26-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>