From 26e0909e516a91281c2ad1fcac23405f3cc1ee11 Mon Sep 17 00:00:00 2001 From: Nick Mathewson Date: Fri, 27 Oct 2017 14:28:02 -0400 Subject: [PATCH] In the hsdescv3 fuzzer, replace the decryption function. The new decryption function performs no decryption, skips the salt, and doesn't check the mac. This allows us to fuzz the hs_descriptor.c code using unencrypted descriptor test, and exercise more of the code. Related to 21509. --- changes/hsdescv3_fuzz_more | 3 +++ src/or/hs_descriptor.c | 12 ++++++------ src/or/hs_descriptor.h | 7 +++++++ src/test/fuzz/fuzz_hsdescv3.c | 19 +++++++++++++++++++ 4 files changed, 35 insertions(+), 6 deletions(-) create mode 100644 changes/hsdescv3_fuzz_more diff --git a/changes/hsdescv3_fuzz_more b/changes/hsdescv3_fuzz_more new file mode 100644 index 0000000000..25626bb9a4 --- /dev/null +++ b/changes/hsdescv3_fuzz_more @@ -0,0 +1,3 @@ + o Minor features (testing): + - Our fuzzing tests now test the encrypted portions of the + v3 hidden service descriptors. Implements more of 21509. diff --git a/src/or/hs_descriptor.c b/src/or/hs_descriptor.c index 4bc54bdb2d..a8ff3471c7 100644 --- a/src/or/hs_descriptor.c +++ b/src/or/hs_descriptor.c @@ -1303,12 +1303,12 @@ encrypted_data_length_is_valid(size_t len) * generate the right decryption keys; set decrypted_out to the * plaintext. If is_superencrypted_layer is set, this is the outter * encrypted layer of the descriptor. */ -static size_t -decrypt_desc_layer(const hs_descriptor_t *desc, - const uint8_t *encrypted_blob, - size_t encrypted_blob_size, - int is_superencrypted_layer, - char **decrypted_out) +MOCK_IMPL(STATIC size_t, +decrypt_desc_layer,(const hs_descriptor_t *desc, + const uint8_t *encrypted_blob, + size_t encrypted_blob_size, + int is_superencrypted_layer, + char **decrypted_out)) { uint8_t *decrypted = NULL; uint8_t secret_key[HS_DESC_ENCRYPTED_KEY_LEN], secret_iv[CIPHER_IV_LEN]; diff --git a/src/or/hs_descriptor.h b/src/or/hs_descriptor.h index 971e856647..7730ce09f0 100644 --- a/src/or/hs_descriptor.h +++ b/src/or/hs_descriptor.h @@ -261,6 +261,13 @@ STATIC size_t decode_superencrypted(const char *message, size_t message_len, uint8_t **encrypted_out); STATIC void desc_plaintext_data_free_contents(hs_desc_plaintext_data_t *desc); +MOCK_DECL(STATIC size_t, decrypt_desc_layer,(const hs_descriptor_t *desc, + const uint8_t *encrypted_blob, + size_t encrypted_blob_size, + int is_superencrypted_layer, + char **decrypted_out)); + + #endif /* defined(HS_DESCRIPTOR_PRIVATE) */ #endif /* !defined(TOR_HS_DESCRIPTOR_H) */ diff --git a/src/test/fuzz/fuzz_hsdescv3.c b/src/test/fuzz/fuzz_hsdescv3.c index 03c509e2e6..30e82c9252 100644 --- a/src/test/fuzz/fuzz_hsdescv3.c +++ b/src/test/fuzz/fuzz_hsdescv3.c @@ -35,12 +35,31 @@ mock_rsa_ed25519_crosscert_check(const uint8_t *crosscert, return 0; } +static size_t +mock_decrypt_desc_layer(const hs_descriptor_t *desc, + const uint8_t *encrypted_blob, + size_t encrypted_blob_size, + int is_superencrypted_layer, + char **decrypted_out) +{ + (void)is_superencrypted_layer; + (void)desc; + const size_t overhead = HS_DESC_ENCRYPTED_SALT_LEN + DIGEST256_LEN; + if (encrypted_blob_size < overhead) + return 0; + *decrypted_out = tor_memdup_nulterm( + encrypted_blob + HS_DESC_ENCRYPTED_SALT_LEN, + encrypted_blob_size - overhead); + return strlen(*decrypted_out); +} + int fuzz_init(void) { disable_signature_checking(); MOCK(dump_desc, mock_dump_desc__nodump); MOCK(rsa_ed25519_crosscert_check, mock_rsa_ed25519_crosscert_check); + MOCK(decrypt_desc_layer, mock_decrypt_desc_layer); ed25519_init(); return 0; }