| // Copyright 2020, The Android Open Source Project |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #![allow(dead_code)] |
| |
| //! This module implements methods to load legacy keystore key blob files. |
| |
| use crate::{ |
| database::KeyMetaData, |
| error::{Error as KsError, ResponseCode}, |
| key_parameter::{KeyParameter, KeyParameterValue}, |
| super_key::SuperKeyManager, |
| utils::uid_to_android_user, |
| }; |
| use android_hardware_security_keymint::aidl::android::hardware::security::keymint::{ |
| SecurityLevel::SecurityLevel, Tag::Tag, TagType::TagType, |
| }; |
| use anyhow::{Context, Result}; |
| use keystore2_crypto::{aes_gcm_decrypt, derive_key_from_password, ZVec}; |
| use std::io::{ErrorKind, Read}; |
| use std::{convert::TryInto, fs::File, path::Path, path::PathBuf}; |
| |
| const SUPPORTED_LEGACY_BLOB_VERSION: u8 = 3; |
| |
| mod flags { |
| /// This flag is deprecated. It is here to support keys that have been written with this flag |
| /// set, but we don't create any new keys with this flag. |
| pub const ENCRYPTED: u8 = 1 << 0; |
| /// This flag is deprecated. It indicates that the blob was generated and thus owned by a |
| /// software fallback Keymaster implementation. Keymaster 1.0 was the last Keymaster version |
| /// that could be accompanied by a software fallback. With the removal of Keymaster 1.0 |
| /// support, this flag is obsolete. |
| pub const FALLBACK: u8 = 1 << 1; |
| /// KEYSTORE_FLAG_SUPER_ENCRYPTED is for blobs that are already encrypted by KM but have |
| /// an additional layer of password-based encryption applied. The same encryption scheme is used |
| /// as KEYSTORE_FLAG_ENCRYPTED. The latter is deprecated. |
| pub const SUPER_ENCRYPTED: u8 = 1 << 2; |
| /// KEYSTORE_FLAG_CRITICAL_TO_DEVICE_ENCRYPTION is for blobs that are part of device encryption |
| /// flow so it receives special treatment from keystore. For example this blob will not be super |
| /// encrypted, and it will be stored separately under a unique UID instead. This flag should |
| /// only be available to system uid. |
| pub const CRITICAL_TO_DEVICE_ENCRYPTION: u8 = 1 << 3; |
| /// The blob is associated with the security level Strongbox as opposed to TEE. |
| pub const STRONGBOX: u8 = 1 << 4; |
| } |
| |
| /// Lagacy key blob types. |
| mod blob_types { |
| /// A generic blob used for non sensitive unstructured blobs. |
| pub const GENERIC: u8 = 1; |
| /// This key is a super encryption key encrypted with AES128 |
| /// and a password derived key. |
| pub const SUPER_KEY: u8 = 2; |
| // Used to be the KEY_PAIR type. |
| const _RESERVED: u8 = 3; |
| /// A KM key blob. |
| pub const KM_BLOB: u8 = 4; |
| /// A legacy key characteristics file. This has only a single list of Authorizations. |
| pub const KEY_CHARACTERISTICS: u8 = 5; |
| /// A key characteristics cache has both a hardware enforced and a software enforced list |
| /// of authorizations. |
| pub const KEY_CHARACTERISTICS_CACHE: u8 = 6; |
| /// Like SUPER_KEY but encrypted with AES256. |
| pub const SUPER_KEY_AES256: u8 = 7; |
| } |
| |
| /// Error codes specific to the legacy blob module. |
| #[derive(thiserror::Error, Debug, Eq, PartialEq)] |
| pub enum Error { |
| /// Returned by the legacy blob module functions if an input stream |
| /// did not have enough bytes to read. |
| #[error("Input stream had insufficient bytes to read.")] |
| BadLen, |
| /// This error code is returned by `Blob::decode_alias` if it encounters |
| /// an invalid alias filename encoding. |
| #[error("Invalid alias filename encoding.")] |
| BadEncoding, |
| } |
| |
| /// The blob payload, optionally with all information required to decrypt it. |
| #[derive(Debug, Eq, PartialEq)] |
| pub enum BlobValue { |
| /// A generic blob used for non sensitive unstructured blobs. |
| Generic(Vec<u8>), |
| /// A legacy key characteristics file. This has only a single list of Authorizations. |
| Characteristics(Vec<u8>), |
| /// A key characteristics cache has both a hardware enforced and a software enforced list |
| /// of authorizations. |
| CharacteristicsCache(Vec<u8>), |
| /// A password encrypted blob. Includes the initialization vector, the aead tag, the |
| /// ciphertext data, a salt, and a key size. The latter two are used for key derivation. |
| PwEncrypted { |
| /// Initialization vector. |
| iv: Vec<u8>, |
| /// Aead tag for integrity verification. |
| tag: Vec<u8>, |
| /// Ciphertext. |
| data: Vec<u8>, |
| /// Salt for key derivation. |
| salt: Vec<u8>, |
| /// Key sise for key derivation. This selects between AES128 GCM and AES256 GCM. |
| key_size: usize, |
| }, |
| /// An encrypted blob. Includes the initialization vector, the aead tag, and the |
| /// ciphertext data. The key can be selected from context, i.e., the owner of the key |
| /// blob. |
| Encrypted { |
| /// Initialization vector. |
| iv: Vec<u8>, |
| /// Aead tag for integrity verification. |
| tag: Vec<u8>, |
| /// Ciphertext. |
| data: Vec<u8>, |
| }, |
| /// Holds the plaintext key blob either after unwrapping an encrypted blob or when the |
| /// blob was stored in "plaintext" on disk. The "plaintext" of a key blob is not actual |
| /// plaintext because all KeyMint blobs are encrypted with a device bound key. The key |
| /// blob in this Variant is decrypted only with respect to any extra layer of encryption |
| /// that Keystore added. |
| Decrypted(ZVec), |
| } |
| |
| /// Represents a loaded legacy key blob file. |
| #[derive(Debug, Eq, PartialEq)] |
| pub struct Blob { |
| flags: u8, |
| value: BlobValue, |
| } |
| |
| /// This object represents a path that holds a legacy Keystore blob database. |
| pub struct LegacyBlobLoader { |
| path: PathBuf, |
| } |
| |
| fn read_bool(stream: &mut dyn Read) -> Result<bool> { |
| const SIZE: usize = std::mem::size_of::<bool>(); |
| let mut buffer: [u8; SIZE] = [0; SIZE]; |
| stream.read_exact(&mut buffer).map(|_| buffer[0] != 0).context("In read_ne_bool.") |
| } |
| |
| fn read_ne_u32(stream: &mut dyn Read) -> Result<u32> { |
| const SIZE: usize = std::mem::size_of::<u32>(); |
| let mut buffer: [u8; SIZE] = [0; SIZE]; |
| stream.read_exact(&mut buffer).map(|_| u32::from_ne_bytes(buffer)).context("In read_ne_u32.") |
| } |
| |
| fn read_ne_i32(stream: &mut dyn Read) -> Result<i32> { |
| const SIZE: usize = std::mem::size_of::<i32>(); |
| let mut buffer: [u8; SIZE] = [0; SIZE]; |
| stream.read_exact(&mut buffer).map(|_| i32::from_ne_bytes(buffer)).context("In read_ne_i32.") |
| } |
| |
| fn read_ne_i64(stream: &mut dyn Read) -> Result<i64> { |
| const SIZE: usize = std::mem::size_of::<i64>(); |
| let mut buffer: [u8; SIZE] = [0; SIZE]; |
| stream.read_exact(&mut buffer).map(|_| i64::from_ne_bytes(buffer)).context("In read_ne_i64.") |
| } |
| |
| impl Blob { |
| /// This blob was generated with a fallback software KM device. |
| pub fn is_fallback(&self) -> bool { |
| self.flags & flags::FALLBACK != 0 |
| } |
| |
| /// This blob is encrypted and needs to be decrypted with the user specific master key |
| /// before use. |
| pub fn is_encrypted(&self) -> bool { |
| self.flags & (flags::SUPER_ENCRYPTED | flags::ENCRYPTED) != 0 |
| } |
| |
| /// This blob is critical to device encryption. It cannot be encrypted with the super key |
| /// because it is itself part of the key derivation process for the key encrypting the |
| /// super key. |
| pub fn is_critical_to_device_encryption(&self) -> bool { |
| self.flags & flags::CRITICAL_TO_DEVICE_ENCRYPTION != 0 |
| } |
| |
| /// This blob is associated with the Strongbox security level. |
| pub fn is_strongbox(&self) -> bool { |
| self.flags & flags::STRONGBOX != 0 |
| } |
| |
| /// Returns the payload data of this blob file. |
| pub fn value(&self) -> &BlobValue { |
| &self.value |
| } |
| |
| /// Consume this blob structure and extract the payload. |
| pub fn take_value(self) -> BlobValue { |
| self.value |
| } |
| } |
| |
| impl LegacyBlobLoader { |
| const IV_SIZE: usize = keystore2_crypto::IV_LENGTH; |
| const GCM_TAG_LENGTH: usize = keystore2_crypto::TAG_LENGTH; |
| const SALT_SIZE: usize = keystore2_crypto::SALT_LENGTH; |
| |
| // The common header has the following structure: |
| // version (1 Byte) |
| // blob_type (1 Byte) |
| // flags (1 Byte) |
| // info (1 Byte) |
| // initialization_vector (16 Bytes) |
| // integrity (MD5 digest or gcb tag) (16 Bytes) |
| // length (4 Bytes) |
| const COMMON_HEADER_SIZE: usize = 4 + Self::IV_SIZE + Self::GCM_TAG_LENGTH + 4; |
| |
| const VERSION_OFFSET: usize = 0; |
| const TYPE_OFFSET: usize = 1; |
| const FLAGS_OFFSET: usize = 2; |
| const SALT_SIZE_OFFSET: usize = 3; |
| const LENGTH_OFFSET: usize = 4 + Self::IV_SIZE + Self::GCM_TAG_LENGTH; |
| const IV_OFFSET: usize = 4; |
| const AEAD_TAG_OFFSET: usize = Self::IV_OFFSET + Self::IV_SIZE; |
| const DIGEST_OFFSET: usize = Self::IV_OFFSET + Self::IV_SIZE; |
| |
| /// Construct a new LegacyBlobLoader with a root path of `path` relative to which it will |
| /// expect legacy key blob files. |
| pub fn new(path: &Path) -> Self { |
| Self { path: path.to_owned() } |
| } |
| /// Encodes an alias string as ascii character sequence in the range |
| /// ['+' .. '.'] and ['0' .. '~']. |
| /// Bytes with values in the range ['0' .. '~'] are represented as they are. |
| /// All other bytes are split into two characters as follows: |
| /// |
| /// msb a a | b b b b b b |
| /// |
| /// The most significant bits (a) are encoded: |
| /// a a character |
| /// 0 0 '+' |
| /// 0 1 ',' |
| /// 1 0 '-' |
| /// 1 1 '.' |
| /// |
| /// The 6 lower bits are represented with the range ['0' .. 'o']: |
| /// b(hex) character |
| /// 0x00 '0' |
| /// ... |
| /// 0x3F 'o' |
| /// |
| /// The function cannot fail because we have a representation for each |
| /// of the 256 possible values of each byte. |
| pub fn encode_alias(name: &str) -> String { |
| let mut acc = String::new(); |
| for c in name.bytes() { |
| match c { |
| b'0'..=b'~' => { |
| acc.push(c as char); |
| } |
| c => { |
| acc.push((b'+' + (c as u8 >> 6)) as char); |
| acc.push((b'0' + (c & 0x3F)) as char); |
| } |
| }; |
| } |
| acc |
| } |
| |
| /// This function reverses the encoding described in `encode_alias`. |
| /// This function can fail, because not all possible character |
| /// sequences are valid code points. And even if the encoding is valid, |
| /// the result may not be a valid UTF-8 sequence. |
| pub fn decode_alias(name: &str) -> Result<String> { |
| let mut multi: Option<u8> = None; |
| let mut s = Vec::<u8>::new(); |
| for c in name.bytes() { |
| multi = match (c, multi) { |
| // m is set, we are processing the second part of a multi byte sequence |
| (b'0'..=b'o', Some(m)) => { |
| s.push(m | (c - b'0')); |
| None |
| } |
| (b'+'..=b'.', None) => Some((c - b'+') << 6), |
| (b'0'..=b'~', None) => { |
| s.push(c); |
| None |
| } |
| _ => { |
| return Err(Error::BadEncoding) |
| .context("In decode_alias: could not decode filename.") |
| } |
| }; |
| } |
| if multi.is_some() { |
| return Err(Error::BadEncoding).context("In decode_alias: could not decode filename."); |
| } |
| |
| String::from_utf8(s).context("In decode_alias: encoded alias was not valid UTF-8.") |
| } |
| |
| fn new_from_stream(stream: &mut dyn Read) -> Result<Blob> { |
| let mut buffer = Vec::new(); |
| stream.read_to_end(&mut buffer).context("In new_from_stream.")?; |
| |
| if buffer.len() < Self::COMMON_HEADER_SIZE { |
| return Err(Error::BadLen).context("In new_from_stream.")?; |
| } |
| |
| let version: u8 = buffer[Self::VERSION_OFFSET]; |
| |
| let flags: u8 = buffer[Self::FLAGS_OFFSET]; |
| let blob_type: u8 = buffer[Self::TYPE_OFFSET]; |
| let is_encrypted = flags & (flags::ENCRYPTED | flags::SUPER_ENCRYPTED) != 0; |
| let salt = match buffer[Self::SALT_SIZE_OFFSET] as usize { |
| Self::SALT_SIZE => Some(&buffer[buffer.len() - Self::SALT_SIZE..buffer.len()]), |
| _ => None, |
| }; |
| |
| if version != SUPPORTED_LEGACY_BLOB_VERSION { |
| return Err(KsError::Rc(ResponseCode::VALUE_CORRUPTED)) |
| .context(format!("In new_from_stream: Unknown blob version: {}.", version)); |
| } |
| |
| let length = u32::from_be_bytes( |
| buffer[Self::LENGTH_OFFSET..Self::LENGTH_OFFSET + 4].try_into().unwrap(), |
| ) as usize; |
| if buffer.len() < Self::COMMON_HEADER_SIZE + length { |
| return Err(Error::BadLen).context(format!( |
| "In new_from_stream. Expected: {} got: {}.", |
| Self::COMMON_HEADER_SIZE + length, |
| buffer.len() |
| )); |
| } |
| let value = &buffer[Self::COMMON_HEADER_SIZE..Self::COMMON_HEADER_SIZE + length]; |
| let iv = &buffer[Self::IV_OFFSET..Self::IV_OFFSET + Self::IV_SIZE]; |
| let tag = &buffer[Self::AEAD_TAG_OFFSET..Self::AEAD_TAG_OFFSET + Self::GCM_TAG_LENGTH]; |
| |
| match (blob_type, is_encrypted, salt) { |
| (blob_types::GENERIC, _, _) => { |
| Ok(Blob { flags, value: BlobValue::Generic(value.to_vec()) }) |
| } |
| (blob_types::KEY_CHARACTERISTICS, _, _) => { |
| Ok(Blob { flags, value: BlobValue::Characteristics(value.to_vec()) }) |
| } |
| (blob_types::KEY_CHARACTERISTICS_CACHE, _, _) => { |
| Ok(Blob { flags, value: BlobValue::CharacteristicsCache(value.to_vec()) }) |
| } |
| (blob_types::SUPER_KEY, _, Some(salt)) => Ok(Blob { |
| flags, |
| value: BlobValue::PwEncrypted { |
| iv: iv.to_vec(), |
| tag: tag.to_vec(), |
| data: value.to_vec(), |
| key_size: keystore2_crypto::AES_128_KEY_LENGTH, |
| salt: salt.to_vec(), |
| }, |
| }), |
| (blob_types::SUPER_KEY_AES256, _, Some(salt)) => Ok(Blob { |
| flags, |
| value: BlobValue::PwEncrypted { |
| iv: iv.to_vec(), |
| tag: tag.to_vec(), |
| data: value.to_vec(), |
| key_size: keystore2_crypto::AES_256_KEY_LENGTH, |
| salt: salt.to_vec(), |
| }, |
| }), |
| (blob_types::KM_BLOB, true, _) => Ok(Blob { |
| flags, |
| value: BlobValue::Encrypted { |
| iv: iv.to_vec(), |
| tag: tag.to_vec(), |
| data: value.to_vec(), |
| }, |
| }), |
| (blob_types::KM_BLOB, false, _) => Ok(Blob { |
| flags, |
| value: BlobValue::Decrypted(value.try_into().context("In new_from_stream.")?), |
| }), |
| (blob_types::SUPER_KEY, _, None) | (blob_types::SUPER_KEY_AES256, _, None) => { |
| Err(KsError::Rc(ResponseCode::VALUE_CORRUPTED)) |
| .context("In new_from_stream: Super key without salt for key derivation.") |
| } |
| _ => Err(KsError::Rc(ResponseCode::VALUE_CORRUPTED)).context(format!( |
| "In new_from_stream: Unknown blob type. {} {}", |
| blob_type, is_encrypted |
| )), |
| } |
| } |
| |
| /// Parses a legacy key blob file read from `stream`. A `decrypt` closure |
| /// must be supplied, that is primed with the appropriate key. |
| /// The callback takes the following arguments: |
| /// * ciphertext: &[u8] - The to-be-deciphered message. |
| /// * iv: &[u8] - The initialization vector. |
| /// * tag: Option<&[u8]> - AEAD tag if AES GCM is selected. |
| /// * salt: Option<&[u8]> - An optional salt. Used for password key derivation. |
| /// * key_size: Option<usize> - An optional key size. Used for pw key derivation. |
| /// |
| /// If no super key is available, the callback must return |
| /// `Err(KsError::Rc(ResponseCode::LOCKED))`. The callback is only called |
| /// if the to-be-read blob is encrypted. |
| pub fn new_from_stream_decrypt_with<F>(mut stream: impl Read, decrypt: F) -> Result<Blob> |
| where |
| F: FnOnce(&[u8], &[u8], &[u8], Option<&[u8]>, Option<usize>) -> Result<ZVec>, |
| { |
| let blob = |
| Self::new_from_stream(&mut stream).context("In new_from_stream_decrypt_with.")?; |
| |
| match blob.value() { |
| BlobValue::Encrypted { iv, tag, data } => Ok(Blob { |
| flags: blob.flags, |
| value: BlobValue::Decrypted( |
| decrypt(&data, &iv, &tag, None, None) |
| .context("In new_from_stream_decrypt_with.")?, |
| ), |
| }), |
| BlobValue::PwEncrypted { iv, tag, data, salt, key_size } => Ok(Blob { |
| flags: blob.flags, |
| value: BlobValue::Decrypted( |
| decrypt(&data, &iv, &tag, Some(salt), Some(*key_size)) |
| .context("In new_from_stream_decrypt_with.")?, |
| ), |
| }), |
| _ => Ok(blob), |
| } |
| } |
| |
| fn tag_type(tag: Tag) -> TagType { |
| TagType((tag.0 as u32 & 0xFF000000u32) as i32) |
| } |
| |
| /// Read legacy key parameter file content. |
| /// Depending on the file type a key characteristics file stores one (TYPE_KEY_CHARACTERISTICS) |
| /// or two (TYPE_KEY_CHARACTERISTICS_CACHE) key parameter lists. The format of the list is as |
| /// follows: |
| /// |
| /// +------------------------------+ |
| /// | 32 bit indirect_size | |
| /// +------------------------------+ |
| /// | indirect_size bytes of data | This is where the blob data is stored |
| /// +------------------------------+ |
| /// | 32 bit element_count | Number of key parameter entries. |
| /// | 32 bit elements_size | Total bytes used by entries. |
| /// +------------------------------+ |
| /// | elements_size bytes of data | This is where the elements are stored. |
| /// +------------------------------+ |
| /// |
| /// Elements have a 32 bit header holding the tag with a tag type encoded in the |
| /// four most significant bits (see android/hardware/secruity/keymint/TagType.aidl). |
| /// The header is immediately followed by the payload. The payload size depends on |
| /// the encoded tag type in the header: |
| /// BOOLEAN : 1 byte |
| /// ENUM, ENUM_REP, UINT, UINT_REP : 4 bytes |
| /// ULONG, ULONG_REP, DATETIME : 8 bytes |
| /// BLOB, BIGNUM : 8 bytes see below. |
| /// |
| /// Bignum and blob payload format: |
| /// +------------------------+ |
| /// | 32 bit blob_length | Length of the indirect payload in bytes. |
| /// | 32 bit indirect_offset | Offset from the beginning of the indirect section. |
| /// +------------------------+ |
| pub fn read_key_parameters(stream: &mut &[u8]) -> Result<Vec<KeyParameterValue>> { |
| let indirect_size = |
| read_ne_u32(stream).context("In read_key_parameters: While reading indirect size.")?; |
| |
| let indirect_buffer = stream |
| .get(0..indirect_size as usize) |
| .ok_or(KsError::Rc(ResponseCode::VALUE_CORRUPTED)) |
| .context("In read_key_parameters: While reading indirect buffer.")?; |
| |
| // update the stream position. |
| *stream = &stream[indirect_size as usize..]; |
| |
| let element_count = |
| read_ne_u32(stream).context("In read_key_parameters: While reading element count.")?; |
| let element_size = |
| read_ne_u32(stream).context("In read_key_parameters: While reading element size.")?; |
| |
| let elements_buffer = stream |
| .get(0..element_size as usize) |
| .ok_or(KsError::Rc(ResponseCode::VALUE_CORRUPTED)) |
| .context("In read_key_parameters: While reading elements buffer.")?; |
| |
| // update the stream position. |
| *stream = &stream[element_size as usize..]; |
| |
| let mut element_stream = &elements_buffer[..]; |
| |
| let mut params: Vec<KeyParameterValue> = Vec::new(); |
| for _ in 0..element_count { |
| let tag = Tag(read_ne_i32(&mut element_stream).context("In read_key_parameters.")?); |
| let param = match Self::tag_type(tag) { |
| TagType::ENUM | TagType::ENUM_REP | TagType::UINT | TagType::UINT_REP => { |
| KeyParameterValue::new_from_tag_primitive_pair( |
| tag, |
| read_ne_i32(&mut element_stream).context("While reading integer.")?, |
| ) |
| .context("Trying to construct integer/enum KeyParameterValue.") |
| } |
| TagType::ULONG | TagType::ULONG_REP | TagType::DATE => { |
| KeyParameterValue::new_from_tag_primitive_pair( |
| tag, |
| read_ne_i64(&mut element_stream).context("While reading long integer.")?, |
| ) |
| .context("Trying to construct long KeyParameterValue.") |
| } |
| TagType::BOOL => { |
| if read_bool(&mut element_stream).context("While reading long integer.")? { |
| KeyParameterValue::new_from_tag_primitive_pair(tag, 1) |
| .context("Trying to construct boolean KeyParameterValue.") |
| } else { |
| Err(anyhow::anyhow!("Invalid.")) |
| } |
| } |
| TagType::BYTES | TagType::BIGNUM => { |
| let blob_size = read_ne_u32(&mut element_stream) |
| .context("While reading blob size.")? |
| as usize; |
| let indirect_offset = read_ne_u32(&mut element_stream) |
| .context("While reading indirect offset.")? |
| as usize; |
| KeyParameterValue::new_from_tag_primitive_pair( |
| tag, |
| indirect_buffer |
| .get(indirect_offset..indirect_offset + blob_size) |
| .context("While reading blob value.")? |
| .to_vec(), |
| ) |
| .context("Trying to construct blob KeyParameterValue.") |
| } |
| TagType::INVALID => Err(anyhow::anyhow!("Invalid.")), |
| _ => { |
| return Err(KsError::Rc(ResponseCode::VALUE_CORRUPTED)) |
| .context("In read_key_parameters: Encountered bogus tag type."); |
| } |
| }; |
| if let Ok(p) = param { |
| params.push(p); |
| } |
| } |
| |
| Ok(params) |
| } |
| |
| fn read_characteristics_file( |
| &self, |
| uid: u32, |
| prefix: &str, |
| alias: &str, |
| hw_sec_level: SecurityLevel, |
| ) -> Result<Vec<KeyParameter>> { |
| let blob = Self::read_generic_blob(&self.make_chr_filename(uid, alias, prefix)) |
| .context("In read_characteristics_file")?; |
| |
| let blob = match blob { |
| None => return Ok(Vec::new()), |
| Some(blob) => blob, |
| }; |
| |
| let mut stream = match blob.value() { |
| BlobValue::Characteristics(data) => &data[..], |
| BlobValue::CharacteristicsCache(data) => &data[..], |
| _ => { |
| return Err(KsError::Rc(ResponseCode::VALUE_CORRUPTED)).context(concat!( |
| "In read_characteristics_file: ", |
| "Characteristics file does not hold key characteristics." |
| )) |
| } |
| }; |
| |
| let hw_list = match blob.value() { |
| // The characteristics cache file has two lists and the first is |
| // the hardware enforced list. |
| BlobValue::CharacteristicsCache(_) => Some( |
| Self::read_key_parameters(&mut stream) |
| .context("In read_characteristics_file.")? |
| .into_iter() |
| .map(|value| KeyParameter::new(value, hw_sec_level)), |
| ), |
| _ => None, |
| }; |
| |
| let sw_list = Self::read_key_parameters(&mut stream) |
| .context("In read_characteristics_file.")? |
| .into_iter() |
| .map(|value| KeyParameter::new(value, SecurityLevel::SOFTWARE)); |
| |
| Ok(hw_list.into_iter().flatten().chain(sw_list).collect()) |
| } |
| |
| // This is a list of known prefixes that the Keystore 1.0 SPI used to use. |
| // * USRPKEY was used for private and secret key material, i.e., KM blobs. |
| // * USRSKEY was used for secret key material, i.e., KM blobs, before Android P. |
| // * CACERT was used for key chains or free standing public certificates. |
| // * USRCERT was used for public certificates of USRPKEY entries. But KeyChain also |
| // used this for user installed certificates without private key material. |
| |
| fn read_km_blob_file(&self, uid: u32, alias: &str) -> Result<Option<(Blob, String)>> { |
| let mut iter = ["USRPKEY", "USERSKEY"].iter(); |
| |
| let (blob, prefix) = loop { |
| if let Some(prefix) = iter.next() { |
| if let Some(blob) = |
| Self::read_generic_blob(&self.make_blob_filename(uid, alias, prefix)) |
| .context("In read_km_blob_file.")? |
| { |
| break (blob, prefix); |
| } |
| } else { |
| return Ok(None); |
| } |
| }; |
| |
| Ok(Some((blob, prefix.to_string()))) |
| } |
| |
| fn read_generic_blob(path: &Path) -> Result<Option<Blob>> { |
| let mut file = match File::open(path) { |
| Ok(file) => file, |
| Err(e) => match e.kind() { |
| ErrorKind::NotFound => return Ok(None), |
| _ => return Err(e).context("In read_generic_blob."), |
| }, |
| }; |
| |
| Ok(Some(Self::new_from_stream(&mut file).context("In read_generic_blob.")?)) |
| } |
| |
| /// This function constructs the blob file name which has the form: |
| /// user_<android user id>/<uid>_<alias>. |
| fn make_blob_filename(&self, uid: u32, alias: &str, prefix: &str) -> PathBuf { |
| let mut path = self.path.clone(); |
| let user_id = uid_to_android_user(uid); |
| let encoded_alias = Self::encode_alias(&format!("{}_{}", prefix, alias)); |
| path.push(format!("user_{}", user_id)); |
| path.push(format!("{}_{}", uid, encoded_alias)); |
| path |
| } |
| |
| /// This function constructs the characteristics file name which has the form: |
| /// user_<android user id>/.<uid>_chr_<alias>. |
| fn make_chr_filename(&self, uid: u32, alias: &str, prefix: &str) -> PathBuf { |
| let mut path = self.path.clone(); |
| let user_id = uid_to_android_user(uid); |
| let encoded_alias = Self::encode_alias(&format!("{}_{}", prefix, alias)); |
| path.push(format!("user_{}", user_id)); |
| path.push(format!(".{}_chr_{}", uid, encoded_alias)); |
| path |
| } |
| |
| fn load_by_uid_alias( |
| &self, |
| uid: u32, |
| alias: &str, |
| key_manager: &SuperKeyManager, |
| ) -> Result<(Option<(Blob, Vec<KeyParameter>)>, Option<Vec<u8>>, Option<Vec<u8>>, KeyMetaData)> |
| { |
| let metadata = KeyMetaData::new(); |
| |
| let km_blob = self.read_km_blob_file(uid, alias).context("In load_by_uid_alias.")?; |
| |
| let km_blob = match km_blob { |
| Some((km_blob, prefix)) => { |
| let km_blob = |
| match km_blob { |
| Blob { flags: _, value: BlobValue::Decrypted(_) } => km_blob, |
| // Unwrap the key blob if required. |
| Blob { flags, value: BlobValue::Encrypted { iv, tag, data } } => { |
| let decrypted = match key_manager |
| .get_per_boot_key_by_user_id(uid_to_android_user(uid)) |
| { |
| Some(key) => aes_gcm_decrypt(&data, &iv, &tag, &key).context( |
| "In load_by_uid_alias: while trying to decrypt legacy blob.", |
| )?, |
| None => { |
| return Err(KsError::Rc(ResponseCode::LOCKED)).context(format!( |
| concat!( |
| "In load_by_uid_alias: ", |
| "User {} has not unlocked the keystore yet.", |
| ), |
| uid_to_android_user(uid) |
| )) |
| } |
| }; |
| Blob { flags, value: BlobValue::Decrypted(decrypted) } |
| } |
| _ => return Err(KsError::Rc(ResponseCode::VALUE_CORRUPTED)).context( |
| "In load_by_uid_alias: Found wrong blob type in legacy key blob file.", |
| ), |
| }; |
| |
| let hw_sec_level = match km_blob.is_strongbox() { |
| true => SecurityLevel::STRONGBOX, |
| false => SecurityLevel::TRUSTED_ENVIRONMENT, |
| }; |
| let key_parameters = self |
| .read_characteristics_file(uid, &prefix, alias, hw_sec_level) |
| .context("In load_by_uid_alias.")?; |
| Some((km_blob, key_parameters)) |
| } |
| None => None, |
| }; |
| |
| let user_cert = |
| match Self::read_generic_blob(&self.make_blob_filename(uid, alias, "USRCERT")) |
| .context("In load_by_uid_alias: While loading user cert.")? |
| { |
| Some(Blob { value: BlobValue::Generic(data), .. }) => Some(data), |
| None => None, |
| _ => { |
| return Err(KsError::Rc(ResponseCode::VALUE_CORRUPTED)).context( |
| "In load_by_uid_alias: Found unexpected blob type in USRCERT file", |
| ) |
| } |
| }; |
| |
| let ca_cert = match Self::read_generic_blob(&self.make_blob_filename(uid, alias, "CACERT")) |
| .context("In load_by_uid_alias: While loading ca cert.")? |
| { |
| Some(Blob { value: BlobValue::Generic(data), .. }) => Some(data), |
| None => None, |
| _ => { |
| return Err(KsError::Rc(ResponseCode::VALUE_CORRUPTED)) |
| .context("In load_by_uid_alias: Found unexpected blob type in CACERT file") |
| } |
| }; |
| |
| Ok((km_blob, user_cert, ca_cert, metadata)) |
| } |
| |
| /// Load and decrypt legacy super key blob. |
| pub fn load_super_key(&self, user_id: u32, pw: &[u8]) -> Result<Option<ZVec>> { |
| let mut path = self.path.clone(); |
| path.push(&format!("user_{}", user_id)); |
| path.push(".masterkey"); |
| let blob = Self::read_generic_blob(&path) |
| .context("In load_super_key: While loading super key.")?; |
| |
| let blob = match blob { |
| Some(blob) => match blob { |
| Blob { |
| value: BlobValue::PwEncrypted { iv, tag, data, salt, key_size }, .. |
| } => { |
| let key = derive_key_from_password(pw, Some(&salt), key_size) |
| .context("In load_super_key: Failed to derive key from password.")?; |
| let blob = aes_gcm_decrypt(&data, &iv, &tag, &key).context( |
| "In load_super_key: while trying to decrypt legacy super key blob.", |
| )?; |
| Some(blob) |
| } |
| _ => { |
| return Err(KsError::Rc(ResponseCode::VALUE_CORRUPTED)).context( |
| "In load_super_key: Found wrong blob type in legacy super key blob file.", |
| ) |
| } |
| }, |
| None => None, |
| }; |
| |
| Ok(blob) |
| } |
| } |
| |
| #[cfg(test)] |
| mod test { |
| use super::*; |
| use anyhow::anyhow; |
| use keystore2_crypto::aes_gcm_decrypt; |
| use rand::Rng; |
| use std::string::FromUtf8Error; |
| mod legacy_blob_test_vectors; |
| use crate::error; |
| use crate::legacy_blob::test::legacy_blob_test_vectors::*; |
| use crate::test::utils::TempDir; |
| |
| #[test] |
| fn decode_encode_alias_test() { |
| static ALIAS: &str = "#({}test[])😗"; |
| static ENCODED_ALIAS: &str = "+S+X{}test[]+Y.`-O-H-G"; |
| // Second multi byte out of range ------v |
| static ENCODED_ALIAS_ERROR1: &str = "+S+{}test[]+Y"; |
| // Incomplete multi byte ------------------------v |
| static ENCODED_ALIAS_ERROR2: &str = "+S+X{}test[]+"; |
| // Our encoding: ".`-O-H-G" |
| // is UTF-8: 0xF0 0x9F 0x98 0x97 |
| // is UNICODE: U+1F617 |
| // is 😗 |
| // But +H below is a valid encoding for 0x18 making this sequence invalid UTF-8. |
| static ENCODED_ALIAS_ERROR_UTF8: &str = ".`-O+H-G"; |
| |
| assert_eq!(ENCODED_ALIAS, &LegacyBlobLoader::encode_alias(ALIAS)); |
| assert_eq!(ALIAS, &LegacyBlobLoader::decode_alias(ENCODED_ALIAS).unwrap()); |
| assert_eq!( |
| Some(&Error::BadEncoding), |
| LegacyBlobLoader::decode_alias(ENCODED_ALIAS_ERROR1) |
| .unwrap_err() |
| .root_cause() |
| .downcast_ref::<Error>() |
| ); |
| assert_eq!( |
| Some(&Error::BadEncoding), |
| LegacyBlobLoader::decode_alias(ENCODED_ALIAS_ERROR2) |
| .unwrap_err() |
| .root_cause() |
| .downcast_ref::<Error>() |
| ); |
| assert!(LegacyBlobLoader::decode_alias(ENCODED_ALIAS_ERROR_UTF8) |
| .unwrap_err() |
| .root_cause() |
| .downcast_ref::<FromUtf8Error>() |
| .is_some()); |
| |
| for _i in 0..100 { |
| // Any valid UTF-8 string should be en- and decoded without loss. |
| let alias_str = rand::thread_rng().gen::<[char; 20]>().iter().collect::<String>(); |
| let random_alias = alias_str.as_bytes(); |
| let encoded = LegacyBlobLoader::encode_alias(&alias_str); |
| let decoded = match LegacyBlobLoader::decode_alias(&encoded) { |
| Ok(d) => d, |
| Err(_) => panic!(format!("random_alias: {:x?}\nencoded {}", random_alias, encoded)), |
| }; |
| assert_eq!(random_alias.to_vec(), decoded.bytes().collect::<Vec<u8>>()); |
| } |
| } |
| |
| #[test] |
| fn read_golden_key_blob_test() -> anyhow::Result<()> { |
| let blob = LegacyBlobLoader::new_from_stream_decrypt_with(&mut &*BLOB, |_, _, _, _, _| { |
| Err(anyhow!("should not be called")) |
| })?; |
| assert!(!blob.is_encrypted()); |
| assert!(!blob.is_fallback()); |
| assert!(!blob.is_strongbox()); |
| assert!(!blob.is_critical_to_device_encryption()); |
| assert_eq!(blob.value(), &BlobValue::Generic([0xde, 0xed, 0xbe, 0xef].to_vec())); |
| |
| let blob = LegacyBlobLoader::new_from_stream_decrypt_with( |
| &mut &*REAL_LEGACY_BLOB, |
| |_, _, _, _, _| Err(anyhow!("should not be called")), |
| )?; |
| assert!(!blob.is_encrypted()); |
| assert!(!blob.is_fallback()); |
| assert!(!blob.is_strongbox()); |
| assert!(!blob.is_critical_to_device_encryption()); |
| assert_eq!( |
| blob.value(), |
| &BlobValue::Decrypted(REAL_LEGACY_BLOB_PAYLOAD.try_into().unwrap()) |
| ); |
| Ok(()) |
| } |
| |
| #[test] |
| fn read_aes_gcm_encrypted_key_blob_test() { |
| let blob = LegacyBlobLoader::new_from_stream_decrypt_with( |
| &mut &*AES_GCM_ENCRYPTED_BLOB, |
| |d, iv, tag, salt, key_size| { |
| assert_eq!(salt, None); |
| assert_eq!(key_size, None); |
| assert_eq!( |
| iv, |
| &[ |
| 0xbd, 0xdb, 0x8d, 0x69, 0x72, 0x56, 0xf0, 0xf5, 0xa4, 0x02, 0x88, 0x7f, |
| 0x00, 0x00, 0x00, 0x00, |
| ] |
| ); |
| assert_eq!( |
| tag, |
| &[ |
| 0x50, 0xd9, 0x97, 0x95, 0x37, 0x6e, 0x28, 0x6a, 0x28, 0x9d, 0x51, 0xb9, |
| 0xb9, 0xe0, 0x0b, 0xc3 |
| ][..] |
| ); |
| aes_gcm_decrypt(d, iv, tag, AES_KEY).context("Trying to decrypt blob.") |
| }, |
| ) |
| .unwrap(); |
| assert!(blob.is_encrypted()); |
| assert!(!blob.is_fallback()); |
| assert!(!blob.is_strongbox()); |
| assert!(!blob.is_critical_to_device_encryption()); |
| |
| assert_eq!(blob.value(), &BlobValue::Decrypted(DECRYPTED_PAYLOAD.try_into().unwrap())); |
| } |
| |
| #[test] |
| fn read_golden_key_blob_too_short_test() { |
| let error = |
| LegacyBlobLoader::new_from_stream_decrypt_with(&mut &BLOB[0..15], |_, _, _, _, _| { |
| Err(anyhow!("should not be called")) |
| }) |
| .unwrap_err(); |
| assert_eq!(Some(&Error::BadLen), error.root_cause().downcast_ref::<Error>()); |
| } |
| |
| #[test] |
| fn test_legacy_blobs() -> anyhow::Result<()> { |
| let temp_dir = TempDir::new("legacy_blob_test")?; |
| std::fs::create_dir(&*temp_dir.build().push("user_0"))?; |
| |
| std::fs::write(&*temp_dir.build().push("user_0").push(".masterkey"), SUPERKEY)?; |
| |
| std::fs::write( |
| &*temp_dir.build().push("user_0").push("10223_USRPKEY_authbound"), |
| USRPKEY_AUTHBOUND, |
| )?; |
| std::fs::write( |
| &*temp_dir.build().push("user_0").push(".10223_chr_USRPKEY_authbound"), |
| USRPKEY_AUTHBOUND_CHR, |
| )?; |
| std::fs::write( |
| &*temp_dir.build().push("user_0").push("10223_USRCERT_authbound"), |
| USRCERT_AUTHBOUND, |
| )?; |
| std::fs::write( |
| &*temp_dir.build().push("user_0").push("10223_CACERT_authbound"), |
| CACERT_AUTHBOUND, |
| )?; |
| |
| std::fs::write( |
| &*temp_dir.build().push("user_0").push("10223_USRPKEY_non_authbound"), |
| USRPKEY_NON_AUTHBOUND, |
| )?; |
| std::fs::write( |
| &*temp_dir.build().push("user_0").push(".10223_chr_USRPKEY_non_authbound"), |
| USRPKEY_NON_AUTHBOUND_CHR, |
| )?; |
| std::fs::write( |
| &*temp_dir.build().push("user_0").push("10223_USRCERT_non_authbound"), |
| USRCERT_NON_AUTHBOUND, |
| )?; |
| std::fs::write( |
| &*temp_dir.build().push("user_0").push("10223_CACERT_non_authbound"), |
| CACERT_NON_AUTHBOUND, |
| )?; |
| |
| let key_manager = crate::super_key::SuperKeyManager::new(); |
| let mut db = crate::database::KeystoreDB::new(temp_dir.path())?; |
| let legacy_blob_loader = LegacyBlobLoader::new(temp_dir.path()); |
| |
| assert_eq!( |
| legacy_blob_loader |
| .load_by_uid_alias(10223, "authbound", &key_manager) |
| .unwrap_err() |
| .root_cause() |
| .downcast_ref::<error::Error>(), |
| Some(&error::Error::Rc(ResponseCode::LOCKED)) |
| ); |
| |
| key_manager.unlock_user_key(0, PASSWORD, &mut db, &legacy_blob_loader)?; |
| |
| if let (Some((Blob { flags, value }, _params)), Some(cert), Some(chain), _kp) = |
| legacy_blob_loader.load_by_uid_alias(10223, "authbound", &key_manager)? |
| { |
| assert_eq!(flags, 4); |
| assert_eq!(value, BlobValue::Decrypted(DECRYPTED_USRPKEY_AUTHBOUND.try_into()?)); |
| assert_eq!(&cert[..], LOADED_CERT_AUTHBOUND); |
| assert_eq!(&chain[..], LOADED_CACERT_AUTHBOUND); |
| } else { |
| panic!(""); |
| } |
| if let (Some((Blob { flags, value }, _params)), Some(cert), Some(chain), _kp) = |
| legacy_blob_loader.load_by_uid_alias(10223, "non_authbound", &key_manager)? |
| { |
| assert_eq!(flags, 0); |
| assert_eq!(value, BlobValue::Decrypted(LOADED_USRPKEY_NON_AUTHBOUND.try_into()?)); |
| assert_eq!(&cert[..], LOADED_CERT_NON_AUTHBOUND); |
| assert_eq!(&chain[..], LOADED_CACERT_NON_AUTHBOUND); |
| } else { |
| panic!(""); |
| } |
| |
| Ok(()) |
| } |
| } |