From f78b6daf26f6618f67d7ba6029695158904ea557 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 15 Oct 2019 11:16:38 -0700 Subject: [PATCH] common/encrypt: support verifying ciphertext of v2 encryption policies Update _verify_ciphertext_for_encryption_policy() to support v2 encryption policies. This also required adding HKDF-SHA512 support to fscrypt-crypt-util. Signed-off-by: Eric Biggers Reviewed-by: Eryu Guan Signed-off-by: Eryu Guan --- common/encrypt | 58 ++++++-- src/fscrypt-crypt-util.c | 304 ++++++++++++++++++++++++++++++++++----- 2 files changed, 316 insertions(+), 46 deletions(-) diff --git a/common/encrypt b/common/encrypt index 1335d222..90f931fc 100644 --- a/common/encrypt +++ b/common/encrypt @@ -382,9 +382,16 @@ _get_encryption_nonce() # flags: 0x2 # master_key_descriptor: 0000000000000000 # nonce: EFBD18765DF6414EC0A2CD5F91297E12 + # + # Also support the case where the whole xattr is printed as hex, + # as is the case for fscrypt_context_v2. + # + # xattr: e_name_index:9 e_name:c e_name_len:1 e_value_size:40 e_value: + # 020104020000000033809BFEBE68A4AD264079B30861DD5E6B9E72D07523C58794ACF52534BAA756 + # $DUMP_F2FS_PROG -i $inode $device | awk ' /\/ { found = 1 } - /^nonce:/ && found { + (/^nonce:/ || /^[[:xdigit:]]+$/) && found { print substr($0, length($0) - 31, 32); found = 0; }' @@ -405,6 +412,11 @@ _require_get_encryption_nonce_support() ;; f2fs) _require_command "$DUMP_F2FS_PROG" dump.f2fs + # For fscrypt_context_v2, we actually need a f2fs-tools version + # that has the patch "f2fs-tools: improve xattr value printing" + # (https://sourceforge.net/p/linux-f2fs/mailman/message/36648640/). + # Otherwise the xattr is incorrectly parsed as v1. But just let + # the test fail in that case, as it was an f2fs-tools bug... ;; *) _notrun "_get_encryption_nonce() isn't implemented on $FSTYP" @@ -554,7 +566,7 @@ _do_verify_ciphertext_for_encryption_policy() local filenames_encryption_mode=$2 local policy_flags=$3 local set_encpolicy_args=$4 - local keydesc=$5 + local keyspec=$5 local raw_key_hex=$6 local crypt_cmd="$here/src/fscrypt-crypt-util $7" @@ -576,7 +588,7 @@ _do_verify_ciphertext_for_encryption_policy() done dir=$SCRATCH_MNT/encdir mkdir $dir - _set_encpolicy $dir $keydesc $set_encpolicy_args -f $policy_flags + _set_encpolicy $dir $keyspec $set_encpolicy_args -f $policy_flags for src in $tmp.testfile_*; do dst=$dir/${src##*.} cp $src $dst @@ -596,7 +608,7 @@ _do_verify_ciphertext_for_encryption_policy() dir=$SCRATCH_MNT/encdir.pad$padding mkdir $dir dir_inode=$(stat -c %i $dir) - _set_encpolicy $dir $keydesc $set_encpolicy_args \ + _set_encpolicy $dir $keyspec $set_encpolicy_args \ -f $((policy_flags | padding_flag)) for len in 1 3 15 16 17 32 100 254 255; do name=$(tr -d -C a-zA-Z0-9 < /dev/urandom | head -c $len) @@ -670,12 +682,14 @@ _fscrypt_mode_name_to_num() # policy of the specified type is used. # # The first two parameters are the contents and filenames encryption modes to -# test. Optionally, also specify 'direct' to test the DIRECT_KEY flag. +# test. Optionally, also specify 'direct' to test the DIRECT_KEY flag, and/or +# 'v2' to test v2 policies. _verify_ciphertext_for_encryption_policy() { local contents_encryption_mode=$1 local filenames_encryption_mode=$2 local opt + local policy_version=1 local policy_flags=0 local set_encpolicy_args="" local crypt_util_args="" @@ -683,6 +697,9 @@ _verify_ciphertext_for_encryption_policy() shift 2 for opt; do case "$opt" in + v2) + policy_version=2 + ;; direct) if [ $contents_encryption_mode != \ $filenames_encryption_mode ]; then @@ -701,10 +718,18 @@ _verify_ciphertext_for_encryption_policy() set_encpolicy_args+=" -c $contents_mode_num" set_encpolicy_args+=" -n $filenames_mode_num" - if (( policy_flags & 0x04 )); then - crypt_util_args+=" --kdf=none" + if (( policy_version > 1 )); then + set_encpolicy_args+=" -v 2" + crypt_util_args+=" --kdf=HKDF-SHA512" + if (( policy_flags & 0x04 )); then + crypt_util_args+=" --mode-num=$contents_mode_num" + fi else - crypt_util_args+=" --kdf=AES-128-ECB" + if (( policy_flags & 0x04 )); then + crypt_util_args+=" --kdf=none" + else + crypt_util_args+=" --kdf=AES-128-ECB" + fi fi set_encpolicy_args=${set_encpolicy_args# } @@ -713,7 +738,9 @@ _verify_ciphertext_for_encryption_policy() _require_xfs_io_command "fiemap" _require_get_encryption_nonce_support _require_get_ciphertext_filename_support - _require_command "$KEYCTL_PROG" keyctl + if (( policy_version == 1 )); then + _require_command "$KEYCTL_PROG" keyctl + fi echo "Creating encryption-capable filesystem" >> $seqres.full _scratch_mkfs_encrypted &>> $seqres.full @@ -721,9 +748,14 @@ _verify_ciphertext_for_encryption_policy() echo "Generating encryption key" >> $seqres.full local raw_key=$(_generate_raw_encryption_key) - local keydesc=$(_generate_key_descriptor) - _new_session_keyring - _add_session_encryption_key $keydesc $raw_key + if (( policy_version > 1 )); then + local keyspec=$(_add_enckey $SCRATCH_MNT "$raw_key" \ + | awk '{print $NF}') + else + local keyspec=$(_generate_key_descriptor) + _new_session_keyring + _add_session_encryption_key $keyspec $raw_key + fi local raw_key_hex=$(echo "$raw_key" | tr -d '\\x') echo @@ -737,7 +769,7 @@ _verify_ciphertext_for_encryption_policy() "$filenames_encryption_mode" \ "$policy_flags" \ "$set_encpolicy_args" \ - "$keydesc" \ + "$keyspec" \ "$raw_key_hex" \ "$crypt_util_args" } diff --git a/src/fscrypt-crypt-util.c b/src/fscrypt-crypt-util.c index 81574a55..f5fd8386 100644 --- a/src/fscrypt-crypt-util.c +++ b/src/fscrypt-crypt-util.c @@ -12,11 +12,11 @@ * * All algorithms are implemented in portable C code to avoid depending on * libcrypto (OpenSSL), and because some fscrypt-supported algorithms aren't - * available in libcrypto anyway (e.g. Adiantum). For simplicity, all crypto - * code here tries to follow the mathematical definitions directly, without - * optimizing for performance or worrying about following security best - * practices such as mitigating side-channel attacks. So, only use this program - * for testing! + * available in libcrypto anyway (e.g. Adiantum), or are only supported in + * recent versions (e.g. HKDF-SHA512). For simplicity, all crypto code here + * tries to follow the mathematical definitions directly, without optimizing for + * performance or worrying about following security best practices such as + * mitigating side-channel attacks. So, only use this program for testing! */ #include @@ -63,8 +63,9 @@ static void usage(FILE *fp) " --decrypt Decrypt instead of encrypt\n" " --file-nonce=NONCE File's nonce as a 32-character hex string\n" " --help Show this help\n" -" --kdf=KDF Key derivation function to use: AES-128-ECB\n" -" or none. Default: none\n" +" --kdf=KDF Key derivation function to use: AES-128-ECB,\n" +" HKDF-SHA512, or none. Default: none\n" +" --mode-num=NUM Derive per-mode key using mode number NUM\n" " --padding=PADDING If last block is partial, zero-pad it to next\n" " PADDING-byte boundary. Default: BLOCK_SIZE\n" , fp); @@ -134,6 +135,11 @@ static inline u32 ror32(u32 v, int n) return (v >> n) | (v << (32 - n)); } +static inline u64 ror64(u64 v, int n) +{ + return (v >> n) | (v << (64 - n)); +} + static inline void xor(u8 *res, const u8 *a, const u8 *b, size_t count) { while (count--) @@ -586,7 +592,7 @@ static void test_aes(void) #endif /* ENABLE_ALG_TESTS */ /*----------------------------------------------------------------------------* - * SHA-256 * + * SHA-512 and SHA-256 * *----------------------------------------------------------------------------*/ /* @@ -594,35 +600,104 @@ static void test_aes(void) * https://csrc.nist.gov/csrc/media/publications/fips/180/2/archive/2002-08-01/documents/fips180-2withchangenotice.pdf */ +#define SHA512_DIGEST_SIZE 64 +#define SHA512_BLOCK_SIZE 128 + #define SHA256_DIGEST_SIZE 32 #define SHA256_BLOCK_SIZE 64 #define Ch(x, y, z) (((x) & (y)) ^ (~(x) & (z))) #define Maj(x, y, z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z))) + +#define Sigma512_0(x) (ror64((x), 28) ^ ror64((x), 34) ^ ror64((x), 39)) +#define Sigma512_1(x) (ror64((x), 14) ^ ror64((x), 18) ^ ror64((x), 41)) +#define sigma512_0(x) (ror64((x), 1) ^ ror64((x), 8) ^ ((x) >> 7)) +#define sigma512_1(x) (ror64((x), 19) ^ ror64((x), 61) ^ ((x) >> 6)) + #define Sigma256_0(x) (ror32((x), 2) ^ ror32((x), 13) ^ ror32((x), 22)) #define Sigma256_1(x) (ror32((x), 6) ^ ror32((x), 11) ^ ror32((x), 25)) #define sigma256_0(x) (ror32((x), 7) ^ ror32((x), 18) ^ ((x) >> 3)) #define sigma256_1(x) (ror32((x), 17) ^ ror32((x), 19) ^ ((x) >> 10)) -static const u32 sha256_iv[8] = { - 0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, - 0x1f83d9ab, 0x5be0cd19, +static const u64 sha512_iv[8] = { + 0x6a09e667f3bcc908, 0xbb67ae8584caa73b, 0x3c6ef372fe94f82b, + 0xa54ff53a5f1d36f1, 0x510e527fade682d1, 0x9b05688c2b3e6c1f, + 0x1f83d9abfb41bd6b, 0x5be0cd19137e2179, }; -static const u32 sha256_round_constants[64] = { - 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, - 0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, - 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786, - 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, - 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, - 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, - 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b, - 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, - 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, - 0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, - 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2, +static const u64 sha512_round_constants[80] = { + 0x428a2f98d728ae22, 0x7137449123ef65cd, 0xb5c0fbcfec4d3b2f, + 0xe9b5dba58189dbbc, 0x3956c25bf348b538, 0x59f111f1b605d019, + 0x923f82a4af194f9b, 0xab1c5ed5da6d8118, 0xd807aa98a3030242, + 0x12835b0145706fbe, 0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2, + 0x72be5d74f27b896f, 0x80deb1fe3b1696b1, 0x9bdc06a725c71235, + 0xc19bf174cf692694, 0xe49b69c19ef14ad2, 0xefbe4786384f25e3, + 0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65, 0x2de92c6f592b0275, + 0x4a7484aa6ea6e483, 0x5cb0a9dcbd41fbd4, 0x76f988da831153b5, + 0x983e5152ee66dfab, 0xa831c66d2db43210, 0xb00327c898fb213f, + 0xbf597fc7beef0ee4, 0xc6e00bf33da88fc2, 0xd5a79147930aa725, + 0x06ca6351e003826f, 0x142929670a0e6e70, 0x27b70a8546d22ffc, + 0x2e1b21385c26c926, 0x4d2c6dfc5ac42aed, 0x53380d139d95b3df, + 0x650a73548baf63de, 0x766a0abb3c77b2a8, 0x81c2c92e47edaee6, + 0x92722c851482353b, 0xa2bfe8a14cf10364, 0xa81a664bbc423001, + 0xc24b8b70d0f89791, 0xc76c51a30654be30, 0xd192e819d6ef5218, + 0xd69906245565a910, 0xf40e35855771202a, 0x106aa07032bbd1b8, + 0x19a4c116b8d2d0c8, 0x1e376c085141ab53, 0x2748774cdf8eeb99, + 0x34b0bcb5e19b48a8, 0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb, + 0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3, 0x748f82ee5defb2fc, + 0x78a5636f43172f60, 0x84c87814a1f0ab72, 0x8cc702081a6439ec, + 0x90befffa23631e28, 0xa4506cebde82bde9, 0xbef9a3f7b2c67915, + 0xc67178f2e372532b, 0xca273eceea26619c, 0xd186b8c721c0c207, + 0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178, 0x06f067aa72176fba, + 0x0a637dc5a2c898a6, 0x113f9804bef90dae, 0x1b710b35131c471b, + 0x28db77f523047d84, 0x32caab7b40c72493, 0x3c9ebe0a15c9bebc, + 0x431d67c49c100d4c, 0x4cc5d4becb3e42b6, 0x597f299cfc657e2a, + 0x5fcb6fab3ad6faec, 0x6c44198c4a475817, }; +/* Compute the SHA-512 digest of the given buffer */ +static void sha512(const u8 *in, size_t inlen, u8 out[SHA512_DIGEST_SIZE]) +{ + const size_t msglen = ROUND_UP(inlen + 17, SHA512_BLOCK_SIZE); + u8 * const msg = xmalloc(msglen); + u64 H[8]; + int i; + + /* super naive way of handling the padding */ + memcpy(msg, in, inlen); + memset(&msg[inlen], 0, msglen - inlen); + msg[inlen] = 0x80; + put_unaligned_be64((u64)inlen * 8, &msg[msglen - sizeof(__be64)]); + in = msg; + + memcpy(H, sha512_iv, sizeof(H)); + do { + u64 a = H[0], b = H[1], c = H[2], d = H[3], + e = H[4], f = H[5], g = H[6], h = H[7]; + u64 W[80]; + + for (i = 0; i < 16; i++) + W[i] = get_unaligned_be64(&in[i * sizeof(__be64)]); + for (; i < ARRAY_SIZE(W); i++) + W[i] = sigma512_1(W[i - 2]) + W[i - 7] + + sigma512_0(W[i - 15]) + W[i - 16]; + for (i = 0; i < ARRAY_SIZE(W); i++) { + u64 T1 = h + Sigma512_1(e) + Ch(e, f, g) + + sha512_round_constants[i] + W[i]; + u64 T2 = Sigma512_0(a) + Maj(a, b, c); + + h = g; g = f; f = e; e = d + T1; + d = c; c = b; b = a; a = T1 + T2; + } + H[0] += a; H[1] += b; H[2] += c; H[3] += d; + H[4] += e; H[5] += f; H[6] += g; H[7] += h; + } while ((in += SHA512_BLOCK_SIZE) != &msg[msglen]); + + for (i = 0; i < ARRAY_SIZE(H); i++) + put_unaligned_be64(H[i], &out[i * sizeof(__be64)]); + free(msg); +} + /* Compute the SHA-256 digest of the given buffer */ static void sha256(const u8 *in, size_t inlen, u8 out[SHA256_DIGEST_SIZE]) { @@ -638,7 +713,8 @@ static void sha256(const u8 *in, size_t inlen, u8 out[SHA256_DIGEST_SIZE]) put_unaligned_be64((u64)inlen * 8, &msg[msglen - sizeof(__be64)]); in = msg; - memcpy(H, sha256_iv, sizeof(H)); + for (i = 0; i < ARRAY_SIZE(H); i++) + H[i] = (u32)(sha512_iv[i] >> 32); do { u32 a = H[0], b = H[1], c = H[2], d = H[3], e = H[4], f = H[5], g = H[6], h = H[7]; @@ -651,7 +727,7 @@ static void sha256(const u8 *in, size_t inlen, u8 out[SHA256_DIGEST_SIZE]) sigma256_0(W[i - 15]) + W[i - 16]; for (i = 0; i < ARRAY_SIZE(W); i++) { u32 T1 = h + Sigma256_1(e) + Ch(e, f, g) + - sha256_round_constants[i] + W[i]; + (u32)(sha512_round_constants[i] >> 32) + W[i]; u32 T2 = Sigma256_0(a) + Maj(a, b, c); h = g; g = f; f = e; e = d + T1; @@ -674,8 +750,8 @@ static void test_sha2(void) while (num_tests--) { u8 in[4096]; - u8 digest[SHA256_DIGEST_SIZE]; - u8 ref_digest[SHA256_DIGEST_SIZE]; + u8 digest[SHA512_DIGEST_SIZE]; + u8 ref_digest[SHA512_DIGEST_SIZE]; const size_t inlen = rand() % (1 + sizeof(in)); rand_bytes(in, inlen); @@ -683,6 +759,124 @@ static void test_sha2(void) sha256(in, inlen, digest); SHA256(in, inlen, ref_digest); ASSERT(memcmp(digest, ref_digest, SHA256_DIGEST_SIZE) == 0); + + sha512(in, inlen, digest); + SHA512(in, inlen, ref_digest); + ASSERT(memcmp(digest, ref_digest, SHA512_DIGEST_SIZE) == 0); + } +} +#endif /* ENABLE_ALG_TESTS */ + +/*----------------------------------------------------------------------------* + * HKDF implementation * + *----------------------------------------------------------------------------*/ + +static void hmac_sha512(const u8 *key, size_t keylen, const u8 *msg, + size_t msglen, u8 mac[SHA512_DIGEST_SIZE]) +{ + u8 *ibuf = xmalloc(SHA512_BLOCK_SIZE + msglen); + u8 obuf[SHA512_BLOCK_SIZE + SHA512_DIGEST_SIZE]; + + ASSERT(keylen <= SHA512_BLOCK_SIZE); /* keylen > bs not implemented */ + + memset(ibuf, 0x36, SHA512_BLOCK_SIZE); + xor(ibuf, ibuf, key, keylen); + memcpy(&ibuf[SHA512_BLOCK_SIZE], msg, msglen); + + memset(obuf, 0x5c, SHA512_BLOCK_SIZE); + xor(obuf, obuf, key, keylen); + sha512(ibuf, SHA512_BLOCK_SIZE + msglen, &obuf[SHA512_BLOCK_SIZE]); + sha512(obuf, sizeof(obuf), mac); + + free(ibuf); +} + +static void hkdf_sha512(const u8 *ikm, size_t ikmlen, + const u8 *salt, size_t saltlen, + const u8 *info, size_t infolen, + u8 *output, size_t outlen) +{ + static const u8 default_salt[SHA512_DIGEST_SIZE]; + u8 prk[SHA512_DIGEST_SIZE]; /* pseudorandom key */ + u8 *buf = xmalloc(1 + infolen + SHA512_DIGEST_SIZE); + u8 counter = 1; + size_t i; + + if (saltlen == 0) { + salt = default_salt; + saltlen = sizeof(default_salt); + } + + /* HKDF-Extract */ + ASSERT(ikmlen > 0); + hmac_sha512(salt, saltlen, ikm, ikmlen, prk); + + /* HKDF-Expand */ + for (i = 0; i < outlen; i += SHA512_DIGEST_SIZE) { + u8 *p = buf; + u8 tmp[SHA512_DIGEST_SIZE]; + + ASSERT(counter != 0); + if (i > 0) { + memcpy(p, &output[i - SHA512_DIGEST_SIZE], + SHA512_DIGEST_SIZE); + p += SHA512_DIGEST_SIZE; + } + memcpy(p, info, infolen); + p += infolen; + *p++ = counter++; + hmac_sha512(prk, sizeof(prk), buf, p - buf, tmp); + memcpy(&output[i], tmp, MIN(sizeof(tmp), outlen - i)); + } + free(buf); +} + +#ifdef ENABLE_ALG_TESTS +#include +#include +static void openssl_hkdf_sha512(const u8 *ikm, size_t ikmlen, + const u8 *salt, size_t saltlen, + const u8 *info, size_t infolen, + u8 *output, size_t outlen) +{ + EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL); + size_t actual_outlen = outlen; + + ASSERT(pctx != NULL); + ASSERT(EVP_PKEY_derive_init(pctx) > 0); + ASSERT(EVP_PKEY_CTX_set_hkdf_md(pctx, EVP_sha512()) > 0); + ASSERT(EVP_PKEY_CTX_set1_hkdf_key(pctx, ikm, ikmlen) > 0); + ASSERT(EVP_PKEY_CTX_set1_hkdf_salt(pctx, salt, saltlen) > 0); + ASSERT(EVP_PKEY_CTX_add1_hkdf_info(pctx, info, infolen) > 0); + ASSERT(EVP_PKEY_derive(pctx, output, &actual_outlen) > 0); + ASSERT(actual_outlen == outlen); + EVP_PKEY_CTX_free(pctx); +} + +static void test_hkdf_sha512(void) +{ + unsigned long num_tests = NUM_ALG_TEST_ITERATIONS; + + while (num_tests--) { + u8 ikm[SHA512_DIGEST_SIZE]; + u8 salt[SHA512_DIGEST_SIZE]; + u8 info[128]; + u8 actual_output[512]; + u8 expected_output[sizeof(actual_output)]; + size_t ikmlen = 1 + (rand() % sizeof(ikm)); + size_t saltlen = rand() % (1 + sizeof(salt)); + size_t infolen = rand() % (1 + sizeof(info)); + size_t outlen = rand() % (1 + sizeof(actual_output)); + + rand_bytes(ikm, ikmlen); + rand_bytes(salt, saltlen); + rand_bytes(info, infolen); + + hkdf_sha512(ikm, ikmlen, salt, saltlen, info, infolen, + actual_output, outlen); + openssl_hkdf_sha512(ikm, ikmlen, salt, saltlen, info, infolen, + expected_output, outlen); + ASSERT(memcmp(actual_output, expected_output, outlen) == 0); } } #endif /* ENABLE_ALG_TESTS */ @@ -1476,6 +1670,7 @@ static void crypt_loop(const struct fscrypt_cipher *cipher, const u8 *key, enum kdf_algorithm { KDF_NONE, KDF_AES_128_ECB, + KDF_HKDF_SHA512, }; static enum kdf_algorithm parse_kdf_algorithm(const char *arg) @@ -1484,21 +1679,36 @@ static enum kdf_algorithm parse_kdf_algorithm(const char *arg) return KDF_NONE; if (strcmp(arg, "AES-128-ECB") == 0) return KDF_AES_128_ECB; + if (strcmp(arg, "HKDF-SHA512") == 0) + return KDF_HKDF_SHA512; die("Unknown KDF: %s", arg); } +static u8 parse_mode_number(const char *arg) +{ + char *tmp; + long num = strtol(arg, &tmp, 10); + + if (num <= 0 || *tmp || (u8)num != num) + die("Invalid mode number: %s", arg); + return num; +} + /* * Get the key and starting IV with which the encryption will actually be done. - * If a KDF was specified, a subkey is derived from the master key and file - * nonce. Otherwise, the master key is used directly. + * If a KDF was specified, a subkey is derived from the master key and the mode + * number or file nonce. Otherwise, the master key is used directly. */ static void get_key_and_iv(const u8 *master_key, size_t master_key_size, enum kdf_algorithm kdf, - const u8 nonce[FILE_NONCE_SIZE], + u8 mode_num, const u8 nonce[FILE_NONCE_SIZE], u8 *real_key, size_t real_key_size, struct fscrypt_iv *iv) { + bool nonce_in_iv = false; struct aes_key aes_key; + u8 info[8 + 1 + FILE_NONCE_SIZE] = "fscrypt"; + size_t infolen = 8; size_t i; ASSERT(real_key_size <= master_key_size); @@ -1507,22 +1717,43 @@ static void get_key_and_iv(const u8 *master_key, size_t master_key_size, switch (kdf) { case KDF_NONE: + if (mode_num != 0) + die("--mode-num isn't supported with --kdf=none"); memcpy(real_key, master_key, real_key_size); - if (nonce != NULL) - memcpy(&iv->bytes[8], nonce, FILE_NONCE_SIZE); + nonce_in_iv = true; break; case KDF_AES_128_ECB: if (nonce == NULL) die("--file-nonce is required with --kdf=AES-128-ECB"); + if (mode_num != 0) + die("--mode-num isn't supported with --kdf=AES-128-ECB"); STATIC_ASSERT(FILE_NONCE_SIZE == AES_128_KEY_SIZE); ASSERT(real_key_size % AES_BLOCK_SIZE == 0); aes_setkey(&aes_key, nonce, AES_128_KEY_SIZE); for (i = 0; i < real_key_size; i += AES_BLOCK_SIZE) aes_encrypt(&aes_key, &master_key[i], &real_key[i]); break; + case KDF_HKDF_SHA512: + if (mode_num != 0) { + info[infolen++] = 3; /* HKDF_CONTEXT_PER_MODE_KEY */ + info[infolen++] = mode_num; + nonce_in_iv = true; + } else if (nonce != NULL) { + info[infolen++] = 2; /* HKDF_CONTEXT_PER_FILE_KEY */ + memcpy(&info[infolen], nonce, FILE_NONCE_SIZE); + infolen += FILE_NONCE_SIZE; + } else { + die("With --kdf=HKDF-SHA512, at least one of --file-nonce and --mode-num must be specified"); + } + hkdf_sha512(master_key, master_key_size, NULL, 0, + info, infolen, real_key, real_key_size); + break; default: ASSERT(0); } + + if (nonce_in_iv && nonce != NULL) + memcpy(&iv->bytes[8], nonce, FILE_NONCE_SIZE); } enum { @@ -1531,6 +1762,7 @@ enum { OPT_FILE_NONCE, OPT_HELP, OPT_KDF, + OPT_MODE_NUM, OPT_PADDING, }; @@ -1540,6 +1772,7 @@ static const struct option longopts[] = { { "file-nonce", required_argument, NULL, OPT_FILE_NONCE }, { "help", no_argument, NULL, OPT_HELP }, { "kdf", required_argument, NULL, OPT_KDF }, + { "mode-num", required_argument, NULL, OPT_MODE_NUM }, { "padding", required_argument, NULL, OPT_PADDING }, { NULL, 0, NULL, 0 }, }; @@ -1551,6 +1784,7 @@ int main(int argc, char *argv[]) u8 _file_nonce[FILE_NONCE_SIZE]; u8 *file_nonce = NULL; enum kdf_algorithm kdf = KDF_NONE; + u8 mode_num = 0; size_t padding = 0; const struct fscrypt_cipher *cipher; u8 master_key[MAX_KEY_SIZE]; @@ -1565,6 +1799,7 @@ int main(int argc, char *argv[]) #ifdef ENABLE_ALG_TESTS test_aes(); test_sha2(); + test_hkdf_sha512(); test_aes_256_xts(); test_aes_256_cts_cbc(); test_adiantum(); @@ -1592,6 +1827,9 @@ int main(int argc, char *argv[]) case OPT_KDF: kdf = parse_kdf_algorithm(optarg); break; + case OPT_MODE_NUM: + mode_num = parse_mode_number(optarg); + break; case OPT_PADDING: padding = strtoul(optarg, &tmp, 10); if (padding <= 0 || *tmp || !is_power_of_2(padding) || @@ -1625,7 +1863,7 @@ int main(int argc, char *argv[]) if (master_key_size < cipher->keysize) die("Master key is too short for cipher %s", cipher->name); - get_key_and_iv(master_key, master_key_size, kdf, file_nonce, + get_key_and_iv(master_key, master_key_size, kdf, mode_num, file_nonce, real_key, cipher->keysize, &iv); crypt_loop(cipher, real_key, &iv, decrypting, block_size, padding); -- 2.30.2