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efi_loader: validate load option

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For passing the optional data of the load option to the loaded imaged
protocol we need its size.

efi_deserialize_load_option() is changed to return the size of the optional
data.

As a by-product we get a partial validation of the load option.
Checking the length of the device path remains to be implemented.

Some Coverity defects identified the load options as user input because
get_unaligned_le32() and get_unaligned_le16() is called. But non of these
Coverity defects can be resolved without marking functions with Coverity
specific tags.

Reported-by: Coverity (CID 303760)
Reported-by: Coverity (CID 303768)
Reported-by: Coverity (CID 303776)
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
This commit is contained in:
Heinrich Schuchardt 2020-05-31 22:46:09 +02:00
parent ecd4d99f65
commit 0e69bcfb27
3 changed files with 55 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
cmd/efidebug.c
View File

@ -694,14 +694,19 @@ static int do_efi_boot_rm(struct cmd_tbl *cmdtp, int flag,
*
* Decode the value of UEFI load option variable and print information.
*/
static void show_efi_boot_opt_data(u16 *varname16, void *data, size_t size)
static void show_efi_boot_opt_data(u16 *varname16, void *data, size_t *size)
{
struct efi_load_option lo;
char *label, *p;
size_t label_len16, label_len;
u16 *dp_str;
efi_status_t ret;
efi_deserialize_load_option(&lo, data);
ret = efi_deserialize_load_option(&lo, data, size);
if (ret != EFI_SUCCESS) {
printf("%ls: invalid load option\n", varname16);
return;
}
label_len16 = u16_strlen(lo.label);
label_len = utf16_utf8_strnlen(lo.label, label_len16);
@ -728,8 +733,7 @@ static void show_efi_boot_opt_data(u16 *varname16, void *data, size_t size)
printf(" data:\n");
print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1,
lo.optional_data, size + (u8 *)data -
(u8 *)lo.optional_data, true);
lo.optional_data, *size, true);
free(label);
}
@ -759,7 +763,7 @@ static void show_efi_boot_opt(u16 *varname16)
&efi_global_variable_guid,
NULL, &size, data));
if (ret == EFI_SUCCESS)
show_efi_boot_opt_data(varname16, data, size);
show_efi_boot_opt_data(varname16, data, &size);
free(data);
}
}
@ -920,7 +924,12 @@ static int show_efi_boot_order(void)
goto out;
}
efi_deserialize_load_option(&lo, data);
ret = efi_deserialize_load_option(&lo, data, &size);
if (ret != EFI_SUCCESS) {
printf("%ls: invalid load option\n", var_name16);
ret = CMD_RET_FAILURE;
goto out;
}
label_len16 = u16_strlen(lo.label);
label_len = utf16_utf8_strnlen(lo.label, label_len16);

3
include/efi_loader.h
View File

@ -708,7 +708,8 @@ struct efi_load_option {
const u8 *optional_data;
};
void efi_deserialize_load_option(struct efi_load_option *lo, u8 *data);
efi_status_t efi_deserialize_load_option(struct efi_load_option *lo, u8 *data,
efi_uintn_t *size);
unsigned long efi_serialize_load_option(struct efi_load_option *lo, u8 **data);
efi_status_t efi_bootmgr_load(efi_handle_t *handle);

46
lib/efi_loader/efi_bootmgr.c
View File

@ -36,24 +36,50 @@ static const struct efi_runtime_services *rs;
*
* @lo: pointer to target
* @data: serialized data
* @size: size of the load option, on return size of the optional data
* Return: status code
*/
void efi_deserialize_load_option(struct efi_load_option *lo, u8 *data)
efi_status_t efi_deserialize_load_option(struct efi_load_option *lo, u8 *data,
efi_uintn_t *size)
{
efi_uintn_t len;
len = sizeof(u32);
if (*size < len + 2 * sizeof(u16))
return EFI_INVALID_PARAMETER;
lo->attributes = get_unaligned_le32(data);
data += sizeof(u32);
data += len;
*size -= len;
len = sizeof(u16);
lo->file_path_length = get_unaligned_le16(data);
data += sizeof(u16);
data += len;
*size -= len;
/* FIXME */
lo->label = (u16 *)data;
data += (u16_strlen(lo->label) + 1) * sizeof(u16);
len = u16_strnlen(lo->label, *size / sizeof(u16) - 1);
if (lo->label[len])
return EFI_INVALID_PARAMETER;
len = (len + 1) * sizeof(u16);
if (*size < len)
return EFI_INVALID_PARAMETER;
data += len;
*size -= len;
/* FIXME */
len = lo->file_path_length;
if (*size < len)
return EFI_INVALID_PARAMETER;
lo->file_path = (struct efi_device_path *)data;
data += lo->file_path_length;
/*
* TODO: validate device path. There should be an end node within
* the indicated file_path_length.
*/
data += len;
*size -= len;
lo->optional_data = data;
return EFI_SUCCESS;
}
/**
@ -168,7 +194,11 @@ static efi_status_t try_load_entry(u16 n, efi_handle_t *handle)
if (!load_option)
return EFI_LOAD_ERROR;
efi_deserialize_load_option(&lo, load_option);
ret = efi_deserialize_load_option(&lo, load_option, &size);
if (ret != EFI_SUCCESS) {
log_warning("Invalid load option for %ls\n", varname);
goto error;
}
if (lo.attributes & LOAD_OPTION_ACTIVE) {
u32 attributes;