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Previous patches enabled SetVariableRT using a RAM backend.
Although EBBR [0] defines a variable format we can teach userspace tools
and write the altered variables, it's better if we skip the ABI
requirements completely.
So let's add a new variable, in its own namespace called "VarToFile"
which contains a binary dump of the updated RT, BS and, NV variables
and will be updated when GetVariable is called.
Some adjustments are needed to do that.
Currently we discard BS-only variables in EBS(). We need to preserve
those on the RAM backend that exposes the variables. Since BS-only
variables can't appear at runtime we need to move the memory masking
checks from efi_var_collect() to efi_get_next_variable_name_mem()/
efi_get_variable_mem() and do the filtering at runtime.
We also need an efi_var_collect() variant available at runtime, in order
to construct the "VarToFile" buffer on the fly.
All users and applications (for linux) have to do when updating a variable
is dd that variable in the file described by "RTStorageVolatile".
Linux efivarfs uses a first 4 bytes of the output to represent attributes
in little-endian format. So, storing variables works like this:
$~ efibootmgr -n 0001
$~ dd if=/sys/firmware/efi/efivars/VarToFile-b2ac5fc9-92b7-4acd-aeac-11e818c3130c of=/boot/efi/ubootefi.var skip=4 bs=1
[0] https://arm-software.github.io/ebbr/index.html#document-chapter5-variable-storage
Suggested-by: Ard Biesheuvel <ardb@kernel.org> # dumping all variables to a variable
Co-developed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com> # contributed on efi_var_collect_mem()
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
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GetVariable() and SetVariable() only accept a 32bit value for attributes.
It makes not sense to define EFI_VARIABLE_READ_ONLY as unsigned long.
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
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The VariableNameSize parameter is in bytes but u16_strnlen() counts u16.
Fix the parameter check for null termination.
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
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In multiple places we need the default GUID matching a variable name.
The patch provides a library function. For secure boot related variables
like 'PK', 'KEK', 'db' a lookup table is used. For all other variable
names EFI_GLOBAL_VARIABLE is returned.
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
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UEFI variable names are typically constants and hence should be defined as
const. Unfortunately some of our API functions do not define the parameters
for UEFI variable names as const. This requires unnecessary conversions.
Adjust parameters of several internal functions to tre UEFI variable names
as const.
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
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Writing variables AuditMode and DeployedMode serves to switch between
Secure Boot modes. Provide a separate value for these in efi_auth_var_type.
With this patch the variables will not be read from from file even if they
are marked as non-volatile by mistake.
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
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The UEFI specification requires that the signature database may only be
stored in tamper-resistant storage. So these variable may not be read
from an unsigned file.
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
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Atish reports that on RISC-V, accessing the EFI variables causes
a kernel panic. An objdump of the file verifies that, since the
global pointer for efi_var_buf ends up in .GOT section which is
not mapped in virtual address space for Linux.
<snip of efi_var_mem_find>
0000000000000084 <efi_var_mem_find>:
84: 715d addi sp,sp,-80
* objdump -dr
0000000000000086 <.LCFI2>:
86: e0a2 sd s0,64(sp)
88: fc26 sd s1,56(sp)
8a: e486 sd ra,72(sp)
8c: f84a sd s2,48(sp)
8e: f44e sd s3,40(sp)
90: f052 sd s4,32(sp)
92: ec56 sd s5,24(sp)
94: 00000497 auipc s1,0x0
94: R_RISCV_GOT_HI20 efi_var_buf
98: 0004b483 ld s1,0(s1) # 94 <.LCFI2+0xe>
98: R_RISCV_PCREL_LO12_I .L0
98: R_RISCV_RELAX *ABS*
* objdump -t
0000000000000084 g F .text.efi_runtime 00000000000000b8 efi_var_mem_find
With the patch applied:
* objdump -dr
0000000000000086 <.LCFI2>:
86: e0a2 sd s0,64(sp)
88: fc26 sd s1,56(sp)
8a: e486 sd ra,72(sp)
8c: f84a sd s2,48(sp)
8e: f44e sd s3,40(sp)
90: f052 sd s4,32(sp)
92: ec56 sd s5,24(sp)
94: 00000497 auipc s1,0x0
94: R_RISCV_PCREL_HI20 .LANCHOR0
94: R_RISCV_RELAX *ABS*
98: 00048493 mv s1,s1
98: R_RISCV_PCREL_LO12_I .L0
98: R_RISCV_RELAX *ABS*
* objdump -t
0000000000000008 l O .data.efi_runtime 0000000000000008 efi_var_buf
On arm64 this works, because there's no .GOT entries for this
and everything is converted to relative references.
* objdump -dr (identical pre-post patch, only the new function shows up)
00000000000000b4 <efi_var_mem_find>:
b4: aa0003ee mov x14, x0
b8: 9000000a adrp x10, 0 <efi_var_mem_compare>
b8: R_AARCH64_ADR_PREL_PG_HI21 .data.efi_runtime
bc: 91000140 add x0, x10, #0x0
bc: R_AARCH64_ADD_ABS_LO12_NC .data.efi_runtime
c0: aa0103ed mov x13, x1
c4: 79400021 ldrh w1, [x1]
c8: aa0203eb mov x11, x2
cc: f9400400 ldr x0, [x0, #8]
d0: b940100c ldr w12, [x0, #16]
d4: 8b0c000c add x12, x0, x12
So let's switch efi_var_buf to static and create a helper function for
anyone that needs to update it.
Fixes: e01aed47d6a0 ("efi_loader: Enable run-time variable support for tee based variables")
Reported-by: Atish Patra <atishp@atishpatra.org>
Tested-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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Currently the size of the buffer to keep UEFI variables in memory is fixed
at 16384 bytes. This size has proven to be too small for some use cases.
Make the size of the memory buffer for UEFI variables customizable.
Reported-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
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Remove a line leading to a warning in make htmldocs.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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We recently added functions for storing/restoring variables
from a file to a memory backed buffer marked as __efi_runtime_data
commit f1f990a8c958 ("efi_loader: memory buffer for variables")
commit 5f7dcf079de8 ("efi_loader: UEFI variable persistence")
Using the same idea we now can support GetVariable() and GetNextVariable()
on the OP-TEE based variables as well.
So let's re-arrange the code a bit and move the commmon code for
accessing variables out of efi_variable.c. Create common functions for
reading variables from memory that both implementations can use on
run-time. Then just use those functions in the run-time variants of the
OP-TEE based EFI variable implementation and initialize the memory
buffer on ExitBootServices()
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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Add documentation for EFI_VAR_FILE_MAGIC used in the file format for UEFI
variables.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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Include a file with the initial values for non-volatile UEFI variables
into the U-Boot binary. If this variable is set, changes to variable PK
will not be allowed.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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To determine if a varible is on the of the authentication variables
PK, KEK, db, dbx we have to check both the name and the GUID.
Provide a function converting the variable-name/guid pair to an enum and
use it consistently.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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When using secure boot functions needed both for file and TEE based UEFI
variables have to be moved to the common code module efi_var_common.c.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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Saving UEFI variable as encoded U-Boot environment variables does not allow
support at runtime.
Provide functions to manage a memory buffer with UEFI variables.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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Persist non-volatile UEFI variables in a file on the EFI system partition.
The file is written whenever a non-volatile UEFI variable is changed after
initialization of the UEFI sub-system.
The file is read during the UEFI sub-system initialization to restore
non-volatile UEFI variables.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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Separate the remaining UEFI variable API functions GetNextVariableName and
QueryVariableInfo() from internal functions implementing them.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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We currently have two implementations of UEFI variables:
* variables provided via an OP-TEE module
* variables stored in the U-Boot environment
Read only variables are up to now only implemented in the U-Boot
environment implementation.
Provide a common interface for both implementations that allows handling
read-only variables.
As variable access is limited to very few source files put variable
related definitions into new include efi_variable.h instead of efi_loader.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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