[PATCH v1 3/4] efi_loader: add an EFI variable with the variable file contents
Ilias Apalodimas
ilias.apalodimas at linaro.org
Sat Apr 6 16:01:54 CEST 2024
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.
Some adjustments are needed to do that. Currently we discard BS-only
variables in EBS(). We need to preserve those on the OS RAM backend
that exposes the variables. Since BS-only variables can't appear at RT
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 to make efi_var_collect() available
at runtime, in order to construct the "VarToFile" buffer with BS, RT &
NV variables.
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 at kernel.org> # dumping all variables to a variable
Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
include/efi_variable.h | 15 +++-
lib/efi_loader/efi_boottime.c | 2 +
lib/efi_loader/efi_var_common.c | 43 +++++------
lib/efi_loader/efi_var_file.c | 1 -
lib/efi_loader/efi_var_mem.c | 90 ++++++++++-------------
lib/efi_loader/efi_variable.c | 118 ++++++++++++++++++++++++------
lib/efi_loader/efi_variable_tee.c | 1 -
7 files changed, 164 insertions(+), 106 deletions(-)
diff --git a/include/efi_variable.h b/include/efi_variable.h
index 42a2b7c52bef..8963339b9bb6 100644
--- a/include/efi_variable.h
+++ b/include/efi_variable.h
@@ -271,13 +271,15 @@ const efi_guid_t *efi_auth_var_get_guid(const u16 *name);
*
* @variable_name_size: size of variable_name buffer in bytes
* @variable_name: name of uefi variable's name in u16
+ * @mask: bitmask with required attributes of variables to be collected.
+ * variables are only collected if all of the required
* @vendor: vendor's guid
*
* Return: status code
*/
efi_status_t __efi_runtime
efi_get_next_variable_name_mem(efi_uintn_t *variable_name_size, u16 *variable_name,
- efi_guid_t *vendor);
+ efi_guid_t *vendor, u32 mask);
/**
* efi_get_variable_mem() - Runtime common code across efi variable
* implementations for GetVariable() from
@@ -289,12 +291,14 @@ efi_get_next_variable_name_mem(efi_uintn_t *variable_name_size, u16 *variable_na
* @data_size: size of the buffer to which the variable value is copied
* @data: buffer to which the variable value is copied
* @timep: authentication time (seconds since start of epoch)
+ * @mask: bitmask with required attributes of variables to be collected.
+ * variables are only collected if all of the required
* Return: status code
*/
efi_status_t __efi_runtime
efi_get_variable_mem(const u16 *variable_name, const efi_guid_t *vendor,
u32 *attributes, efi_uintn_t *data_size, void *data,
- u64 *timep);
+ u64 *timep, u32 mask);
/**
* efi_get_variable_runtime() - runtime implementation of GetVariable()
@@ -334,4 +338,11 @@ efi_get_next_variable_name_runtime(efi_uintn_t *variable_name_size,
*/
void efi_var_buf_update(struct efi_var_file *var_buf);
+/**
+ * efi_prealloced_rt_memory() - Get a pointer to preallocated EFI memory
+ * available at runtime
+ *
+ * Return: pointer to preallocated runtime usable buffer
+ */
+void __efi_runtime *efi_prealloced_rt_memory(void);
#endif
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 1951291747cd..39481c89a688 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -97,6 +97,8 @@ const efi_guid_t efi_guid_load_file_protocol = EFI_LOAD_FILE_PROTOCOL_GUID;
const efi_guid_t efi_guid_load_file2_protocol = EFI_LOAD_FILE2_PROTOCOL_GUID;
/* GUID of the SMBIOS table */
const efi_guid_t smbios_guid = SMBIOS_TABLE_GUID;
+/* used by special U-Boot variables during SetVariableRT */
+const efi_guid_t efi_guid_efi_rt_var_file = U_BOOT_EFI_RT_VAR_FILE_GUID;
static efi_status_t EFIAPI efi_disconnect_controller(
efi_handle_t controller_handle,
diff --git a/lib/efi_loader/efi_var_common.c b/lib/efi_loader/efi_var_common.c
index 07b9603d49f3..4abc90e411e7 100644
--- a/lib/efi_loader/efi_var_common.c
+++ b/lib/efi_loader/efi_var_common.c
@@ -182,7 +182,8 @@ efi_get_variable_runtime(u16 *variable_name, const efi_guid_t *guid,
{
efi_status_t ret;
- ret = efi_get_variable_mem(variable_name, guid, attributes, data_size, data, NULL);
+ ret = efi_get_variable_mem(variable_name, guid, attributes, data_size,
+ data, NULL, EFI_VARIABLE_RUNTIME_ACCESS);
/* Remove EFI_VARIABLE_READ_ONLY flag */
if (attributes)
@@ -195,7 +196,8 @@ efi_status_t __efi_runtime EFIAPI
efi_get_next_variable_name_runtime(efi_uintn_t *variable_name_size,
u16 *variable_name, efi_guid_t *guid)
{
- return efi_get_next_variable_name_mem(variable_name_size, variable_name, guid);
+ return efi_get_next_variable_name_mem(variable_name_size, variable_name,
+ guid, EFI_VARIABLE_RUNTIME_ACCESS);
}
/**
@@ -427,18 +429,15 @@ void *efi_get_var(const u16 *name, const efi_guid_t *vendor, efi_uintn_t *size)
*
* Return: Status code
*/
-efi_status_t __maybe_unused efi_var_collect(struct efi_var_file **bufp, loff_t *lenp,
- u32 check_attr_mask)
+efi_status_t __efi_runtime
+efi_var_collect(struct efi_var_file **bufp, loff_t *lenp, u32 check_attr_mask)
{
size_t len = EFI_VAR_BUF_SIZE;
struct efi_var_file *buf;
struct efi_var_entry *var, *old_var;
size_t old_var_name_length = 2;
- *bufp = NULL; /* Avoid double free() */
- buf = calloc(1, len);
- if (!buf)
- return EFI_OUT_OF_RESOURCES;
+ buf = (struct efi_var_file *)efi_prealloced_rt_memory();
var = buf->var;
old_var = var;
for (;;) {
@@ -451,32 +450,26 @@ efi_status_t __maybe_unused efi_var_collect(struct efi_var_file **bufp, loff_t *
return EFI_BUFFER_TOO_SMALL;
var_name_length = (uintptr_t)buf + len - (uintptr_t)var->name;
- memcpy(var->name, old_var->name, old_var_name_length);
- guidcpy(&var->guid, &old_var->guid);
- ret = efi_get_next_variable_name_int(
- &var_name_length, var->name, &var->guid);
+ efi_memcpy_runtime(var->name, old_var->name, old_var_name_length);
+ efi_memcpy_runtime(&var->guid, &old_var->guid, sizeof(efi_guid_t));
+ ret = efi_get_next_variable_name_mem(&var_name_length, var->name,
+ &var->guid, check_attr_mask);
if (ret == EFI_NOT_FOUND)
break;
- if (ret != EFI_SUCCESS) {
- free(buf);
+ if (ret != EFI_SUCCESS)
return ret;
- }
old_var_name_length = var_name_length;
old_var = var;
data = (u8 *)var->name + old_var_name_length;
data_length = (uintptr_t)buf + len - (uintptr_t)data;
- ret = efi_get_variable_int(var->name, &var->guid,
+ ret = efi_get_variable_mem(var->name, &var->guid,
&var->attr, &data_length, data,
- &var->time);
- if (ret != EFI_SUCCESS) {
- free(buf);
+ &var->time, check_attr_mask);
+ if (ret != EFI_SUCCESS)
return ret;
- }
- if ((var->attr & check_attr_mask) == check_attr_mask) {
- var->length = data_length;
- var = (struct efi_var_entry *)ALIGN((uintptr_t)data + data_length, 8);
- }
+ var->length = data_length;
+ var = (struct efi_var_entry *)ALIGN((uintptr_t)data + data_length, 8);
}
buf->reserved = 0;
@@ -490,5 +483,3 @@ efi_status_t __maybe_unused efi_var_collect(struct efi_var_file **bufp, loff_t *
return EFI_SUCCESS;
}
-
-
diff --git a/lib/efi_loader/efi_var_file.c b/lib/efi_loader/efi_var_file.c
index 413e1794e88c..8614e3d34706 100644
--- a/lib/efi_loader/efi_var_file.c
+++ b/lib/efi_loader/efi_var_file.c
@@ -83,7 +83,6 @@ efi_status_t efi_var_to_file(void)
error:
if (ret != EFI_SUCCESS)
log_err("Failed to persist EFI variables\n");
- free(buf);
return ret;
#else
return EFI_SUCCESS;
diff --git a/lib/efi_loader/efi_var_mem.c b/lib/efi_loader/efi_var_mem.c
index 6c21cec5d457..a7af0604733e 100644
--- a/lib/efi_loader/efi_var_mem.c
+++ b/lib/efi_loader/efi_var_mem.c
@@ -16,6 +16,7 @@
* relocation during SetVirtualAddressMap().
*/
static struct efi_var_file __efi_runtime_data *efi_var_buf;
+static void __efi_runtime_data *efi_rt_prealloced;
static struct efi_var_entry __efi_runtime_data *efi_current_var;
/**
@@ -184,53 +185,6 @@ u64 __efi_runtime efi_var_mem_free(void)
sizeof(struct efi_var_entry);
}
-/**
- * efi_var_mem_bs_del() - delete boot service only variables
- */
-static void efi_var_mem_bs_del(void)
-{
- struct efi_var_entry *var = efi_var_buf->var;
-
- for (;;) {
- struct efi_var_entry *last;
-
- last = (struct efi_var_entry *)
- ((uintptr_t)efi_var_buf + efi_var_buf->length);
- if (var >= last)
- break;
- if (var->attr & EFI_VARIABLE_RUNTIME_ACCESS) {
- u16 *data;
-
- /* skip variable */
- for (data = var->name; *data; ++data)
- ;
- ++data;
- var = (struct efi_var_entry *)
- ALIGN((uintptr_t)data + var->length, 8);
- } else {
- /* delete variable */
- efi_var_mem_del(var);
- }
- }
-}
-
-/**
- * efi_var_mem_notify_exit_boot_services() - ExitBootService callback
- *
- * @event: callback event
- * @context: callback context
- */
-static void EFIAPI
-efi_var_mem_notify_exit_boot_services(struct efi_event *event, void *context)
-{
- EFI_ENTRY("%p, %p", event, context);
-
- /* Delete boot service only variables */
- efi_var_mem_bs_del();
-
- EFI_EXIT(EFI_SUCCESS);
-}
-
/**
* efi_var_mem_notify_exit_boot_services() - SetVirtualMemoryMap callback
*
@@ -241,6 +195,7 @@ static void EFIAPI __efi_runtime
efi_var_mem_notify_virtual_address_map(struct efi_event *event, void *context)
{
efi_convert_pointer(0, (void **)&efi_var_buf);
+ efi_convert_pointer(0, (void **)&efi_rt_prealloced);
efi_current_var = NULL;
}
@@ -261,13 +216,21 @@ efi_status_t efi_var_mem_init(void)
efi_var_buf->magic = EFI_VAR_FILE_MAGIC;
efi_var_buf->length = (uintptr_t)efi_var_buf->var -
(uintptr_t)efi_var_buf;
- /* crc32 for 0 bytes = 0 */
- ret = efi_create_event(EVT_SIGNAL_EXIT_BOOT_SERVICES, TPL_CALLBACK,
- efi_var_mem_notify_exit_boot_services, NULL,
- NULL, &event);
+ /*
+ * efi_var_collect() needs to run at runtime and provide us
+ * copies of variables used for the VarToFile variable.
+ * Preallocate memory equal to the variable storage and
+ * preserve it to copy variables around
+ */
+ ret = efi_allocate_pages(EFI_ALLOCATE_ANY_PAGES,
+ EFI_RUNTIME_SERVICES_DATA,
+ efi_size_in_pages(EFI_VAR_BUF_SIZE),
+ &memory);
if (ret != EFI_SUCCESS)
return ret;
+ efi_rt_prealloced = (void *)(uintptr_t)memory;
+
ret = efi_create_event(EVT_SIGNAL_VIRTUAL_ADDRESS_CHANGE, TPL_CALLBACK,
efi_var_mem_notify_virtual_address_map, NULL,
NULL, &event);
@@ -279,7 +242,7 @@ efi_status_t efi_var_mem_init(void)
efi_status_t __efi_runtime
efi_get_variable_mem(const u16 *variable_name, const efi_guid_t *vendor,
u32 *attributes, efi_uintn_t *data_size, void *data,
- u64 *timep)
+ u64 *timep, u32 mask)
{
efi_uintn_t old_size;
struct efi_var_entry *var;
@@ -291,6 +254,9 @@ efi_get_variable_mem(const u16 *variable_name, const efi_guid_t *vendor,
if (!var)
return EFI_NOT_FOUND;
+ if (mask && !((var->attr & mask) == mask))
+ return EFI_NOT_FOUND;
+
if (attributes)
*attributes = var->attr;
if (timep)
@@ -315,7 +281,8 @@ efi_get_variable_mem(const u16 *variable_name, const efi_guid_t *vendor,
efi_status_t __efi_runtime
efi_get_next_variable_name_mem(efi_uintn_t *variable_name_size,
- u16 *variable_name, efi_guid_t *vendor)
+ u16 *variable_name, efi_guid_t *vendor,
+ u32 mask)
{
struct efi_var_entry *var;
efi_uintn_t len, old_size;
@@ -324,6 +291,7 @@ efi_get_next_variable_name_mem(efi_uintn_t *variable_name_size,
if (!variable_name_size || !variable_name || !vendor)
return EFI_INVALID_PARAMETER;
+skip:
len = *variable_name_size >> 1;
if (u16_strnlen(variable_name, len) == len)
return EFI_INVALID_PARAMETER;
@@ -347,6 +315,11 @@ efi_get_next_variable_name_mem(efi_uintn_t *variable_name_size,
efi_memcpy_runtime(variable_name, var->name, *variable_name_size);
efi_memcpy_runtime(vendor, &var->guid, sizeof(efi_guid_t));
+ if (mask && !((var->attr & mask) == mask)) {
+ *variable_name_size = old_size;
+ goto skip;
+ }
+
return EFI_SUCCESS;
}
@@ -354,3 +327,14 @@ void efi_var_buf_update(struct efi_var_file *var_buf)
{
memcpy(efi_var_buf, var_buf, EFI_VAR_BUF_SIZE);
}
+
+void __efi_runtime *efi_prealloced_rt_memory(void)
+{
+ char *s;
+ int count = EFI_VAR_BUF_SIZE;
+
+ s = (char *)efi_rt_prealloced;
+ while (count--)
+ *s++ = 0;
+ return efi_rt_prealloced;
+}
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index f97c8c57f75c..4f529169ea54 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -22,6 +22,8 @@
#include <u-boot/crc.h>
#include <asm/sections.h>
+static const efi_guid_t __efi_runtime_data efi_guid_efi_rt_var_file =
+ U_BOOT_EFI_RT_VAR_FILE_GUID;
#ifdef CONFIG_EFI_SECURE_BOOT
/**
@@ -208,14 +210,16 @@ efi_get_variable_int(const u16 *variable_name, const efi_guid_t *vendor,
u32 *attributes, efi_uintn_t *data_size, void *data,
u64 *timep)
{
- return efi_get_variable_mem(variable_name, vendor, attributes, data_size, data, timep);
+ return efi_get_variable_mem(variable_name, vendor, attributes, data_size,
+ data, timep, 0);
}
efi_status_t __efi_runtime
efi_get_next_variable_name_int(efi_uintn_t *variable_name_size,
u16 *variable_name, efi_guid_t *vendor)
{
- return efi_get_next_variable_name_mem(variable_name_size, variable_name, vendor);
+ return efi_get_next_variable_name_mem(variable_name_size, variable_name,
+ vendor, 0);
}
/**
@@ -479,6 +483,8 @@ if (IS_ENABLED(CONFIG_EFI_RT_VOLATILE_STORE)) {
efi_uintn_t ret;
bool append, delete;
u64 time = 0;
+ struct efi_var_file *buf;
+ loff_t len;
/*
* Authenticated variables are not supported the rest of the checks
@@ -520,30 +526,60 @@ if (IS_ENABLED(CONFIG_EFI_RT_VOLATILE_STORE)) {
return EFI_NOT_FOUND;
}
- if (delete) {
+ if (!delete) {
+ /*
+ * We always insert new variabes and delete the old one when
+ * appending
+ */
+ len = 2 * (u16_strlen(variable_name) + 1) + data_size +
+ sizeof(struct efi_var_entry);
+ if (var && append)
+ len += 2 * var->length;
+ /*
+ * We will copy the variable update into VarToFile,
+ * account for it twice
+ */
+ len *= 2;
+ if (len > efi_var_mem_free())
+ return EFI_OUT_OF_RESOURCES;
+ if (append && var) {
+ u16 *old_data = var->name;
+
+ for (; *old_data; ++old_data)
+ ;
+ ++old_data;
+ ret = efi_var_mem_ins(variable_name, vendor, attributes,
+ var->length, old_data, data_size,
+ data, time);
+ } else {
+ ret = efi_var_mem_ins(variable_name, vendor, attributes,
+ data_size, data, 0, NULL, time);
+ }
+ } else {
/* EFI_NOT_FOUND has been handled before */
attributes = var->attr;
ret = EFI_SUCCESS;
- } else if (append && var) {
- u16 *old_data = var->name;
-
- for (; *old_data; ++old_data)
- ;
- ++old_data;
- ret = efi_var_mem_ins(variable_name, vendor, attributes,
- var->length, old_data, data_size, data,
- time);
- } else {
- ret = efi_var_mem_ins(variable_name, vendor, attributes,
- data_size, data, 0, NULL, time);
}
-
if (ret != EFI_SUCCESS)
return ret;
/* We are always inserting new variables, get rid of the old copy */
efi_var_mem_del(var);
- return EFI_SUCCESS;
+ /*
+ * Create a volatile variable that userspace apps can dd and
+ * update the file contents
+ */
+ ret = efi_var_collect(&buf, &len, EFI_VARIABLE_NON_VOLATILE);
+ if (ret != EFI_SUCCESS)
+ return ret;
+ var = efi_var_mem_find(&efi_guid_efi_rt_var_file, u"VarToFile", NULL);
+ if (var)
+ efi_var_mem_del(var);
+
+ ret = efi_var_mem_ins(u"VarToFile", &efi_guid_efi_rt_var_file,
+ EFI_VARIABLE_RUNTIME_ACCESS, len, buf, 0,
+ NULL, time);
+ return ret;
} else
return EFI_UNSUPPORTED;
@@ -557,11 +593,11 @@ void efi_variables_boot_exit_notify(void)
const efi_guid_t efi_guid_efi_rt_var_file = U_BOOT_EFI_RT_VAR_FILE_GUID;
const efi_guid_t rt_prop_guid = EFI_RT_PROPERTIES_TABLE_GUID;
efi_status_t ret;
+ struct efi_var_file *buf;
+ loff_t len;
+ bool fail = false;
if (IS_ENABLED(CONFIG_EFI_RT_VOLATILE_STORE)) {
- struct efi_rt_properties_table *rt_prop =
- efi_get_configuration_table(&rt_prop_guid);
-
ret = efi_set_variable_int(u"RTStorageVolatile",
&efi_guid_efi_rt_var_file,
EFI_VARIABLE_BOOTSERVICE_ACCESS |
@@ -569,11 +605,47 @@ void efi_variables_boot_exit_notify(void)
EFI_VARIABLE_READ_ONLY,
sizeof(EFI_VAR_FILE_NAME),
EFI_VAR_FILE_NAME, false);
+ if (ret != EFI_SUCCESS) {
+ fail = true;
+ goto out;
+ }
+
+ ret = efi_var_collect(&buf, &len, EFI_VARIABLE_NON_VOLATILE);
+ if (ret != EFI_SUCCESS) {
+ fail = true;
+ goto out;
+ }
+
+ ret = efi_set_variable_int(u"VarToFile",
+ &efi_guid_efi_rt_var_file,
+ EFI_VARIABLE_BOOTSERVICE_ACCESS |
+ EFI_VARIABLE_RUNTIME_ACCESS,
+ len,
+ buf, false);
if (ret != EFI_SUCCESS)
- rt_prop->runtime_services_supported |= ~EFI_RT_SUPPORTED_SET_VARIABLE;
- else
- log_err("Can't RTStorage. SetVariableRT won't be available\n");
+ fail = true;
+out:
+ if (fail) {
+ efi_set_variable_int(u"RTStorageVolatile",
+ &efi_guid_efi_rt_var_file,
+ EFI_VARIABLE_BOOTSERVICE_ACCESS |
+ EFI_VARIABLE_RUNTIME_ACCESS |
+ EFI_VARIABLE_READ_ONLY, 0, 0,
+ false);
+ efi_set_variable_int(u"VarToFile",
+ &efi_guid_efi_rt_var_file,
+ EFI_VARIABLE_BOOTSERVICE_ACCESS |
+ EFI_VARIABLE_RUNTIME_ACCESS, 0, 0,
+ false);
+ } else {
+ struct efi_rt_properties_table *rt_prop =
+ efi_get_configuration_table(&rt_prop_guid);
+
+ rt_prop->runtime_services_supported |=
+ EFI_RT_SUPPORTED_SET_VARIABLE;
+ }
}
+
/* Switch variable services functions to runtime version */
efi_runtime_services.get_variable = efi_get_variable_runtime;
efi_runtime_services.get_next_variable_name =
diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
index dde135fd9f81..9d0e270591ea 100644
--- a/lib/efi_loader/efi_variable_tee.c
+++ b/lib/efi_loader/efi_variable_tee.c
@@ -969,7 +969,6 @@ void efi_variables_boot_exit_notify(void)
log_err("Can't populate EFI variables. No runtime variables will be available\n");
else
efi_var_buf_update(var_buf);
- free(var_buf);
/* Update runtime service table */
efi_runtime_services.query_variable_info =
--
2.37.2
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