Use `__attribute__((visibility("hidden")))` to hide private functions from the dynamic export table

[flynn162]

In the dynamic library build, Noise_XK_* functions and some private functions (dump, fail, debug, etc.) leaked into the so file's dynamic symbol exports.

readelf -W --dyn-syms /path/to/liboprf-0.4.0/lib/liboprf.so.0

readelf output

[NOTE: UND symbols are omitted]

    58: 0000000000006010   139 FUNC    GLOBAL DEFAULT   14 toprf_Evaluate
    59: 0000000000011960    11 FUNC    GLOBAL DEFAULT   14 Noise_XK_rcode_is_success
    60: 0000000000011830   135 FUNC    GLOBAL DEFAULT   14 Noise_XK_unpack_message_with_auth_level
    61: 0000000000013b20   166 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_get_status
    62: 0000000000004d60     9 FUNC    GLOBAL DEFAULT   14 oprf_KeyGen
    63: 000000000000d760    96 FUNC    GLOBAL DEFAULT   14 Noise_XK_decrypt_and_hash
    64: 000000000001a018     8 OBJECT  GLOBAL DEFAULT   24 log_file
    65: 0000000000013160   460 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_free
    66: 0000000000005a90   296 FUNC    GLOBAL DEFAULT   14 coeff
    67: 000000000000d7c0   224 FUNC    GLOBAL DEFAULT   14 Noise_XK_mix_dh
    68: 0000000000012230   296 FUNC    GLOBAL DEFAULT   14 Noise_XK_serialize_peer_secret
    69: 0000000000012790    25 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_get_static_pub
    70: 00000000000080a0   816 FUNC    GLOBAL DEFAULT   14 tpdkg_start_tp
    71: 0000000000007c40   307 FUNC    GLOBAL DEFAULT   14 tpdkg_peer_input_size
    72: 00000000000126b0   123 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_get_info
    73: 00000000000127b0     7 FUNC    GLOBAL DEFAULT   14 Noise_XK_peer_get_id
    74: 0000000000007f60    13 FUNC    GLOBAL DEFAULT   14 tpdkg_peer_not_done
    75: 0000000000012750     8 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_get_peers_counter
    76: 0000000000012d70  1003 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_create_responder
    77: 00000000000118e0   118 FUNC    GLOBAL DEFAULT   14 Noise_XK_unsafe_unpack_message
    78: 00000000000060a0   237 FUNC    GLOBAL DEFAULT   14 toprf_thresholdcombine
    79: 00000000000127c0   131 FUNC    GLOBAL DEFAULT   14 Noise_XK_peer_get_info
    80: 0000000000004d70   285 FUNC    GLOBAL DEFAULT   14 oprf_Finalize
    81: 0000000000011990   440 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_create
    82: 0000000000007ec0   129 FUNC    GLOBAL DEFAULT   14 tpdkg_peer_set_bufs
    83: 00000000000062f0   668 FUNC    GLOBAL DEFAULT   14 dkg_start
    84: 0000000000014070  1150 FUNC    GLOBAL DEFAULT   14 Noise_XK__session_create_initiator_with_ephemeral
    85: 000000000000cbc0   160 FUNC    GLOBAL DEFAULT   14 tpdkg_recv_err
    86: 0000000000011630    12 FUNC    GLOBAL DEFAULT   14 Noise_XK_uu___is_Stuck
    87: 0000000000011970    12 FUNC    GLOBAL DEFAULT   14 Noise_XK_rcode_is_error
    88: 0000000000012620    43 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_lookup_peer_by_id
    89: 000000000000d170    22 FUNC    GLOBAL DEFAULT   14 Noise_XK_hash
    90: 0000000000007ff0   166 FUNC    GLOBAL DEFAULT   14 tpdkg_tp_set_bufs
    91: 0000000000012650    85 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_lookup_peer_by_static
    92: 000000000000d010     8 FUNC    GLOBAL DEFAULT   14 Noise_XK_bytes_to_nonce
    93: 00000000000116f0    12 FUNC    GLOBAL DEFAULT   14 Noise_XK_uu___is_Conf_level
    94: 0000000000011b50   568 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_create_from_secret
    95: 0000000000006590   503 FUNC    GLOBAL DEFAULT   14 dkg_verify_commitment
    96: 000000000000d060   122 FUNC    GLOBAL DEFAULT   14 Noise_XK_aead_encrypt
    97: 0000000000007f70   117 FUNC    GLOBAL DEFAULT   14 tpdkg_peer_free
    98: 0000000000012740    12 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_sessions_counter_is_saturated
    99: 0000000000006790   268 FUNC    GLOBAL DEFAULT   14 dkg_verify_commitments
   100: 0000000000005760   173 FUNC    GLOBAL DEFAULT   14 oprf_Blind
   101: 0000000000013c90    73 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_get_id
   102: 0000000000012140   240 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_remove_peer
   103: 0000000000011750    12 FUNC    GLOBAL DEFAULT   14 Noise_XK_uu___is_No_level
   104: 0000000000006ab0   326 FUNC    GLOBAL DEFAULT   14 dump
   105: 0000000000011f50   487 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_add_peer
   106: 0000000000012770    25 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_get_static_priv
   107: 0000000000011700    76 FUNC    GLOBAL DEFAULT   14 Noise_XK___proj__Conf_level__item__l
   108: 000000000000d040    25 FUNC    GLOBAL DEFAULT   14 Noise_XK_dh
   109: 0000000000006c00   271 FUNC    GLOBAL DEFAULT   14 fail
   110: 0000000000011780    31 FUNC    GLOBAL DEFAULT   14 Noise_XK_encap_message_p_free
   111: 0000000000006190   345 FUNC    GLOBAL DEFAULT   14 toprf_3hashtdh
   112: 0000000000013330   838 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_write
   113: 0000000000011810    19 FUNC    GLOBAL DEFAULT   14 Noise_XK_pack_message
   114: 000000000000cc60   879 FUNC    GLOBAL DEFAULT   14 tpdkg_cheater_msg
   115: 000000000000d630   220 FUNC    GLOBAL DEFAULT   14 Noise_XK_mix_psk
   116: 0000000000013a40   222 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_compute_next_message_len
   117: 0000000000012730     8 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_get_sessions_counter
   118: 0000000000004e90  1968 FUNC    GLOBAL DEFAULT   14 expand_message_xmd
   119: 0000000000007a30   523 FUNC    GLOBAL DEFAULT   14 tpdkg_tp_peer_msg
   120: 0000000000013bd0   185 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_get_hash
   121: 0000000000011770    11 FUNC    GLOBAL DEFAULT   14 Noise_XK_encap_message_p_is_null
   122: 0000000000006960   336 FUNC    GLOBAL DEFAULT   14 dkg_reconstruct
   123: 0000000000012850    25 FUNC    GLOBAL DEFAULT   14 Noise_XK_peer_get_static
   124: 0000000000013680   955 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_read
   125: 000000000000cfd0    54 FUNC    GLOBAL DEFAULT   14 Noise_XK_lbytes_eq
   126: 0000000000011640    76 FUNC    GLOBAL DEFAULT   14 Noise_XK___proj__Stuck__item___0
   127: 0000000000013ce0   304 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_get_info
   128: 0000000000007f50    13 FUNC    GLOBAL DEFAULT   14 tpdkg_tp_not_done
   129: 000000000000d190   155 FUNC    GLOBAL DEFAULT   14 Noise_XK_mix_hash
   130: 0000000000013fc0   164 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_reached_max_security
   131: 0000000000011980    12 FUNC    GLOBAL DEFAULT   14 Noise_XK_rcode_is_stuck
   132: 000000000000d0e0   132 FUNC    GLOBAL DEFAULT   14 Noise_XK_aead_decrypt
   133: 0000000000005830   186 FUNC    GLOBAL DEFAULT   14 oprf_Unblind
   134: 000000000001a014     4 OBJECT  GLOBAL DEFAULT   24 debug
   135: 00000000000083d0   594 FUNC    GLOBAL DEFAULT   14 tpdkg_start_peer
   136: 0000000000005810    21 FUNC    GLOBAL DEFAULT   14 oprf_Evaluate
   137: 0000000000011e80   197 FUNC    GLOBAL DEFAULT   14 Noise_XK_serialize_device_secret
   138: 0000000000012870  1278 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_create_initiator
   139: 00000000000117a0   102 FUNC    GLOBAL DEFAULT   14 Noise_XK_pack_message_with_conf_level
   140: 0000000000012360   689 FUNC    GLOBAL DEFAULT   14 Noise_XK_deserialize_peer_secret
   141: 0000000000007510   706 FUNC    GLOBAL DEFAULT   14 tpdkg_tp_input_sizes
   142: 0000000000005e10   508 FUNC    GLOBAL DEFAULT   14 toprf_thresholdmult
   143: 000000000000d710    69 FUNC    GLOBAL DEFAULT   14 Noise_XK_encrypt_and_hash
   144: 0000000000011d90   232 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_free
   145: 0000000000007d80   314 FUNC    GLOBAL DEFAULT   14 tpdkg_peer_output_size
   146: 0000000000012760    12 FUNC    GLOBAL DEFAULT   14 Noise_XK_device_peers_counter_is_saturated
   147: 0000000000005bc0   583 FUNC    GLOBAL DEFAULT   14 toprf_create_shares
   148: 00000000000115e0    76 FUNC    GLOBAL DEFAULT   14 Noise_XK___proj__Error__item___0
   149: 000000000000d470   442 FUNC    GLOBAL DEFAULT   14 Noise_XK_kdf
   150: 0000000000013e10    76 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_get_peer_id
   151: 0000000000011760     8 FUNC    GLOBAL DEFAULT   14 Noise_XK___proj__Mkencap_message_p_or_null__item__emp
   152: 0000000000011690    11 FUNC    GLOBAL DEFAULT   14 Noise_XK_uu___is_Auth_level
   153: 00000000000115c0    11 FUNC    GLOBAL DEFAULT   14 Noise_XK_uu___is_Success
   154: 00000000000116a0    75 FUNC    GLOBAL DEFAULT   14 Noise_XK___proj__Auth_level__item__l
   155: 000000000000d230   567 FUNC    GLOBAL DEFAULT   14 Noise_XK_hmac
   156: 0000000000005640   282 FUNC    GLOBAL DEFAULT   14 voprf_hash_to_group
   157: 00000000000144f0   886 FUNC    GLOBAL DEFAULT   14 Noise_XK__session_create_responder_with_ephemeral
   158: 000000000001a008     4 OBJECT  GLOBAL DEFAULT   23 Noise_XK_num_pattern_messages
   159: 000000000000d020    20 FUNC    GLOBAL DEFAULT   14 Noise_XK_dh_secret_to_public
   160: 00000000000118c0    17 FUNC    GLOBAL DEFAULT   14 Noise_XK_unpack_message
   161: 00000000000078d0   352 FUNC    GLOBAL DEFAULT   14 tpdkg_tp_output_size
   162: 00000000000115d0    12 FUNC    GLOBAL DEFAULT   14 Noise_XK_uu___is_Error
   163: 0000000000013e60   345 FUNC    GLOBAL DEFAULT   14 Noise_XK_session_get_peer_info
   164: 000000000000a9b0  8708 FUNC    GLOBAL DEFAULT   14 tpdkg_peer_next
   165: 00000000000068a0   183 FUNC    GLOBAL DEFAULT   14 dkg_finish
   166: 00000000000077e0   233 FUNC    GLOBAL DEFAULT   14 tpdkg_tp_input_size
   167: 0000000000008630  9078 FUNC    GLOBAL DEFAULT   14 tpdkg_tp_next

Possible fix:

• Add __attribute__((visibility("default"))) at the end of public function declarations.
• Compile with -fvisibility=hidden which hides all symbols without a visibility attribute.

Ideally I would recommend visibility("protected") over visibility("default"). The blocker is GNU ld doesn't like visibility("protected") inside public header files. When a client passes visibility("protected") to a function declaration, ld (linktime) will look up the function's symbol name across all translation units (the .o files) but it will not look at dynamic libraries. (This means your clients cannot link against your libraries due to mis-used visibility attributes.) You can split the headers into a public version and a dev version (like what I did for my test project), although that would be a huge fix.

Backgrounder:

On Linux, every symbol in a dylib is publicly exported by default. This is a design decision of the GCC toolchain from the 90s.

As another decision decision, ld.so (the runtime loader) does not maintain a graph data structure for your dylib's dependencies. Instead it serializes the graph into an array and uses that same array for every symbol resolve.

This combined linker-loader behavior does not make sense in the age of the internet as people pull a dozen of libraries for every project. An over-exported symbol table increases the risk of symbol clashing. See also this old PHP bug.

P.S. I suggest using this to trace ld.so's resolution order:

LD_DEBUG=reloc:symbols:bindings ./build/test_library 1>&2 2>/tmp/ld-debug.txt

[stef]

dump, fail, debug being exposed are definitely a problem. the Noise_XK_* functions however are a different topic, and i kind of 1/ expect chances of collisions to be less significant, and 2/ this whole thing is kinda vendored 3rd party dep, i try not to make any changes to it that are not very much necessary.

[flynn162]

It looks like my old build was broken (my build did not link to liboprf-noiseXK)

I pulled the latest commit and rebuilt on Debian 12. Here's the updated symbol list

output

fe1ca95 Merge branch 'enjeck-update-readme'


Symbol table '.dynsym' contains 227 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __snprintf_chk@GLIBC_2.3.4 (2)
     2: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND free@GLIBC_2.2.5 (3)
     3: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND sodium_munlock
     4: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __vfprintf_chk@GLIBC_2.3.4 (2)
     5: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND abort@GLIBC_2.2.5 (3)
     6: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __errno_location@GLIBC_2.2.5 (3)
     7: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND _ITM_deregisterTMCloneTable
     8: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_generichash
     9: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_peer_get_info
    10: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_encap_message_p_free
    11: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_auth_hmacsha256_init
    12: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_peer_get_id
    13: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_core_ristretto255_scalar_reduce
    14: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_scalarmult_ristretto255
    15: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND sodium_memzero
    16: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_core_ristretto255_scalar_random
    17: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __stack_chk_fail@GLIBC_2.4 (4)
    18: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND sodium_mlock
    19: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_core_ristretto255_scalar_invert
    20: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_pack_message_with_conf_level
    21: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_sign_detached
    22: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_rcode_is_success
    23: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND snprintf@GLIBC_2.2.5 (3)
    24: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_core_ristretto255_from_hash
    25: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_auth_hmacsha256_final
    26: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_sign_keypair
    27: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_session_create_responder
    28: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND memset@GLIBC_2.2.5 (3)
    29: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_auth
    30: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_device_create
    31: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND fputc@GLIBC_2.2.5 (3)
    32: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_hash_sha512
    33: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_core_ristretto255_is_valid_point
    34: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_device_lookup_peer_by_id
    35: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_generichash_final
    36: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_sign_verify_detached
    37: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __memcpy_chk@GLIBC_2.3.4 (2)
    38: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_hash_sha512_update
    39: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
    40: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND memcpy@GLIBC_2.14 (5)
    41: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_core_ristretto255_add
    42: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND time@GLIBC_2.2.5 (3)
    43: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_unpack_message_with_auth_level
    44: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_session_write
    45: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND fflush@GLIBC_2.2.5 (3)
    46: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_core_ristretto255_scalar_mul
    47: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_device_free
    48: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_auth_verify
    49: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_core_ristretto255_scalar_add
    50: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND randombytes_buf
    51: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_session_free
    52: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_session_create_initiator
    53: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_device_add_peer
    54: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_session_get_peer_id
    55: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_hash_sha512_final
    56: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_scalarmult_ristretto255_base
    57: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND sodium_memcmp
    58: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_core_ristretto255_scalar_sub
    59: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __memset_chk@GLIBC_2.3.4 (2)
    60: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_aead_decrypt
    61: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND fwrite@GLIBC_2.2.5 (3)
    62: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __fprintf_chk@GLIBC_2.3.4 (2)
    63: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND Noise_XK_session_read
    64: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_generichash_init
    65: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND _ITM_registerTMCloneTable
    66: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_generichash_update
    67: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_scalarmult_base
    68: 0000000000000000     0 FUNC    WEAK   DEFAULT  UND __cxa_finalize@GLIBC_2.2.5 (3)
    69: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_stream_xor
    70: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_hash_sha512_init
    71: 0000000000000000     0 OBJECT  GLOBAL DEFAULT  UND stderr@GLIBC_2.2.5 (3)
    72: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND crypto_auth_hmacsha256_update
    73: 000000000000fe80    12 FUNC    GLOBAL DEFAULT   12 stp_dkg_stpstate_cheater_len
    74: 00000000000102e0   554 FUNC    GLOBAL DEFAULT   12 stp_dkg_start_peer
    75: 0000000000024c20     9 FUNC    GLOBAL DEFAULT   12 crypto_kdf_hkdf_sha256_extract_update
    76: 0000000000008210    12 FUNC    GLOBAL DEFAULT   12 tpdkg_tpstate_cheater_len
    77: 0000000000010eb0   629 FUNC    GLOBAL DEFAULT   12 stp_dkg_peer_input_size
    78: 00000000000074e0   114 FUNC    GLOBAL DEFAULT   12 dkg_vss_verify_commitment
    79: 000000000000fe10     9 FUNC    GLOBAL DEFAULT   12 stp_dkg_peerstate_lt_sk
    80: 000000000001b5b0     9 FUNC    GLOBAL DEFAULT   12 toprf_update_peerstate_sessionid
    81: 00000000000262a0    32 OBJECT  GLOBAL DEFAULT   14 H
    82: 00000000000081e0    10 FUNC    GLOBAL DEFAULT   12 tpdkg_tpstate_size
    83: 0000000000008240   603 FUNC    GLOBAL DEFAULT   12 tpdkg_tp_input_sizes
    84: 000000000001c160    33 FUNC    GLOBAL DEFAULT   12 toprf_update_peerstate_commitment
    85: 000000000000dec0   288 FUNC    GLOBAL DEFAULT   12 toprf_mpc_mul_finish
    86: 0000000000006a60   399 FUNC    GLOBAL DEFAULT   12 dkg_respond_noise_handshake
    87: 00000000000064b0   185 FUNC    GLOBAL DEFAULT   12 dkg_finish
    88: 0000000000024c50   119 FUNC    GLOBAL DEFAULT   12 crypto_kdf_hkdf_sha256_extract
    89: 00000000000066c0   119 FUNC    GLOBAL DEFAULT   12 check_ts
    90: 0000000000007e60    24 FUNC    GLOBAL DEFAULT   12 ntohll
    91: 0000000000024fc0     7 FUNC    GLOBAL DEFAULT   12 crypto_kdf_hkdf_sha256_bytes_min
    92: 000000000002f018     4 OBJECT  GLOBAL DEFAULT   22 debug
    93: 000000000001c130    36 FUNC    GLOBAL DEFAULT   12 toprf_update_peerstate_commitments
    94: 000000000000fdd0    10 FUNC    GLOBAL DEFAULT   12 stp_dkg_peerstate_size
    95: 00000000000070b0   160 FUNC    GLOBAL DEFAULT   12 dkg_recv_err
    96: 00000000000106b0   606 FUNC    GLOBAL DEFAULT   12 stp_dkg_stp_input_sizes
    97: 00000000000081f0     9 FUNC    GLOBAL DEFAULT   12 tpdkg_tpstate_n
    98: 0000000000006570   336 FUNC    GLOBAL DEFAULT   12 dkg_reconstruct
    99: 00000000000067d0   313 FUNC    GLOBAL DEFAULT   12 recv_msg
   100: 0000000000014ff0   764 FUNC    GLOBAL DEFAULT   12 stp_dkg_peer_cheater_msg
   101: 0000000000024fe0    10 FUNC    GLOBAL DEFAULT   12 crypto_kdf_hkdf_sha256_statebytes
   102: 00000000000056a0   352 FUNC    GLOBAL DEFAULT   12 interpolate
   103: 0000000000008180     9 FUNC    GLOBAL DEFAULT   12 tpdkg_peerstate_n
   104: 0000000000006740   142 FUNC    GLOBAL DEFAULT   12 send_msg
   105: 00000000000072a0   564 FUNC    GLOBAL DEFAULT   12 dkg_vss_share
   106: 0000000000024fd0    10 FUNC    GLOBAL DEFAULT   12 crypto_kdf_hkdf_sha256_bytes_max
   107: 000000000000fe60     9 FUNC    GLOBAL DEFAULT   12 stp_dkg_stpstate_n
   108: 0000000000008200     9 FUNC    GLOBAL DEFAULT   12 tpdkg_tpstate_t
   109: 000000000001bad0   477 FUNC    GLOBAL DEFAULT   12 toprf_update_start_peer
   110: 0000000000008190     9 FUNC    GLOBAL DEFAULT   12 tpdkg_peerstate_t
   111: 0000000000007be0   334 FUNC    GLOBAL DEFAULT   12 dump
   112: 0000000000011130   301 FUNC    GLOBAL DEFAULT   12 stp_dkg_peer_output_size
   113: 000000000001b9c0   269 FUNC    GLOBAL DEFAULT   12 toprf_update_stp_set_bufs
   114: 000000000000fe70     9 FUNC    GLOBAL DEFAULT   12 stp_dkg_stpstate_t
   115: 00000000000063a0   272 FUNC    GLOBAL DEFAULT   12 dkg_verify_commitments
   116: 000000000001c0c0    36 FUNC    GLOBAL DEFAULT   12 toprf_update_stpstate_commitments
   117: 000000000000fde0     9 FUNC    GLOBAL DEFAULT   12 stp_dkg_peerstate_n
   118: 0000000000007e40    24 FUNC    GLOBAL DEFAULT   12 htonll
   119: 000000000001c080    13 FUNC    GLOBAL DEFAULT   12 toprf_update_stp_not_done
   120: 0000000000005f40   292 FUNC    GLOBAL DEFAULT   12 polynom
   121: 000000000000feb0     7 FUNC    GLOBAL DEFAULT   12 stp_dkg_stpstate_step
   122: 00000000000088a0   260 FUNC    GLOBAL DEFAULT   12 tpdkg_peer_input_size
   123: 0000000000005cd0   258 FUNC    GLOBAL DEFAULT   12 toprf_thresholdcombine
   124: 00000000000081b0     9 FUNC    GLOBAL DEFAULT   12 tpdkg_peerstate_lt_sk
   125: 000000000001c0f0    13 FUNC    GLOBAL DEFAULT   12 toprf_update_peer_not_done
   126: 000000000000fdf0     9 FUNC    GLOBAL DEFAULT   12 stp_dkg_peerstate_t
   127: 000000000000fe20    12 FUNC    GLOBAL DEFAULT   12 stp_dkg_peerstate_share
   128: 0000000000006910   332 FUNC    GLOBAL DEFAULT   12 dkg_init_noise_handshake
   129: 0000000000008230     7 FUNC    GLOBAL DEFAULT   12 tpdkg_tpstate_step
   130: 0000000000024ce0   718 FUNC    GLOBAL DEFAULT   12 crypto_kdf_hkdf_sha256_expand
   131: 000000000000e4d0   253 FUNC    GLOBAL DEFAULT   12 toprf_mpc_ftmult_zk_commitments
   132: 000000000001b5e0     9 FUNC    GLOBAL DEFAULT   12 toprf_update_stpstate_n
   133: 000000000001c8f0   634 FUNC    GLOBAL DEFAULT   12 toprf_update_stp_output_size
   134: 000000000001bcb0   975 FUNC    GLOBAL DEFAULT   12 toprf_update_peer_set_bufs
   135: 000000000000fe40     8 FUNC    GLOBAL DEFAULT   12 stp_dkg_peerstate_step
   136: 000000000001b630   909 FUNC    GLOBAL DEFAULT   12 toprf_update_start_stp
   137: 0000000000008220     9 FUNC    GLOBAL DEFAULT   12 tpdkg_tpstate_sessionid
   138: 0000000000010630   117 FUNC    GLOBAL DEFAULT   12 stp_dkg_peer_free
   139: 000000000001b5f0     9 FUNC    GLOBAL DEFAULT   12 toprf_update_stpstate_t
   140: 0000000000020430 18389 FUNC    GLOBAL DEFAULT   12 toprf_update_peer_next
   141: 0000000000010910   233 FUNC    GLOBAL DEFAULT   12 stp_dkg_stp_input_size
   142: 0000000000008170    10 FUNC    GLOBAL DEFAULT   12 tpdkg_peerstate_size
   143: 00000000000081a0     9 FUNC    GLOBAL DEFAULT   12 tpdkg_peerstate_sessionid
   144: 0000000000007040   102 FUNC    GLOBAL DEFAULT   12 update_transcript
   145: 000000000001cb70  1527 FUNC    GLOBAL DEFAULT   12 toprf_update_stp_peer_msg
   146: 00000000000089b0   292 FUNC    GLOBAL DEFAULT   12 tpdkg_peer_output_size
   147: 0000000000008b90    13 FUNC    GLOBAL DEFAULT   12 tpdkg_tp_not_done
   148: 0000000000005a40   508 FUNC    GLOBAL DEFAULT   12 toprf_thresholdmult
   149: 0000000000008bb0   117 FUNC    GLOBAL DEFAULT   12 tpdkg_peer_free
   150: 000000000000dfe0   791 FUNC    GLOBAL DEFAULT   12 toprf_mpc_vsps_check
   151: 00000000000081c0    12 FUNC    GLOBAL DEFAULT   12 tpdkg_peerstate_share
   152: 00000000000061e0   442 FUNC    GLOBAL DEFAULT   12 dkg_verify_commitment
   153: 000000000001d170  1197 FUNC    GLOBAL DEFAULT   12 toprf_update_peer_input_size
   154: 000000000000de30   137 FUNC    GLOBAL DEFAULT   12 toprf_mpc_mul_start
   155: 0000000000004ab0  1572 FUNC    GLOBAL DEFAULT   12 expand_message_xmd
   156: 0000000000004990   285 FUNC    GLOBAL DEFAULT   12 oprf_Finalize
   157: 0000000000008c30   155 FUNC    GLOBAL DEFAULT   12 tpdkg_tp_set_bufs
   158: 0000000000005c40   138 FUNC    GLOBAL DEFAULT   12 toprf_Evaluate
   159: 0000000000024c10     9 FUNC    GLOBAL DEFAULT   12 crypto_kdf_hkdf_sha256_extract_init
   160: 000000000000fea0    12 FUNC    GLOBAL DEFAULT   12 stp_dkg_stpstate_commitments
   161: 00000000000051e0   172 FUNC    GLOBAL DEFAULT   12 oprf_Blind
   162: 0000000000005510   389 FUNC    GLOBAL DEFAULT   12 lcoeff
   163: 0000000000007d30   269 FUNC    GLOBAL DEFAULT   12 fail
   164: 0000000000024c30    30 FUNC    GLOBAL DEFAULT   12 crypto_kdf_hkdf_sha256_extract_final
   165: 0000000000005820   537 FUNC    GLOBAL DEFAULT   12 toprf_create_shares
   166: 0000000000024fb0    10 FUNC    GLOBAL DEFAULT   12 crypto_kdf_hkdf_sha256_keybytes
   167: 0000000000009210  8808 FUNC    GLOBAL DEFAULT   12 tpdkg_tp_next
   168: 000000000000e300   464 FUNC    GLOBAL DEFAULT   12 toprf_mpc_ftmult_step1
   169: 000000000002f010     8 OBJECT  GLOBAL DEFAULT   22 log_file
   170: 0000000000010620    14 FUNC    GLOBAL DEFAULT   12 stp_dkg_peer_not_done
   171: 00000000000086a0   506 FUNC    GLOBAL DEFAULT   12 tpdkg_tp_peer_msg
   172: 0000000000007680   340 FUNC    GLOBAL DEFAULT   12 dkg_vss_finish
   173: 00000000000052b0   185 FUNC    GLOBAL DEFAULT   12 oprf_Unblind
   174: 00000000000081d0     7 FUNC    GLOBAL DEFAULT   12 tpdkg_peerstate_step
   175: 00000000000050e0   249 FUNC    GLOBAL DEFAULT   12 voprf_hash_to_group
   176: 000000000001c210  1492 FUNC    GLOBAL DEFAULT   12 toprf_update_stp_input_sizes
   177: 000000000001b580    10 FUNC    GLOBAL DEFAULT   12 toprf_update_peerstate_size
   178: 000000000000fe30    12 FUNC    GLOBAL DEFAULT   12 stp_dkg_peerstate_commitments
   179: 0000000000010510   251 FUNC    GLOBAL DEFAULT   12 stp_dkg_peer_set_bufs
   180: 0000000000006e90   367 FUNC    GLOBAL DEFAULT   12 dkg_noise_decrypt
   181: 000000000001b5d0    10 FUNC    GLOBAL DEFAULT   12 toprf_update_stpstate_size
   182: 000000000000fe00     9 FUNC    GLOBAL DEFAULT   12 stp_dkg_peerstate_sessionid
   183: 000000000001c090    33 FUNC    GLOBAL DEFAULT   12 toprf_update_stpstate_delta
   184: 0000000000005290    21 FUNC    GLOBAL DEFAULT   12 oprf_Evaluate
   185: 000000000000d1e0  3152 FUNC    GLOBAL DEFAULT   12 invertedVDMmatrix
   186: 0000000000010610    13 FUNC    GLOBAL DEFAULT   12 stp_dkg_stp_not_done
   187: 0000000000005800    24 FUNC    GLOBAL DEFAULT   12 coeff
   188: 000000000001b600    12 FUNC    GLOBAL DEFAULT   12 toprf_update_stpstate_cheater_len
   189: 0000000000007210   132 FUNC    GLOBAL DEFAULT   12 dkg_vss_commit
   190: 0000000000014d20   708 FUNC    GLOBAL DEFAULT   12 stp_dkg_stp_cheater_msg
   191: 0000000000008590   270 FUNC    GLOBAL DEFAULT   12 tpdkg_tp_output_size
   192: 0000000000008cd0   797 FUNC    GLOBAL DEFAULT   12 tpdkg_start_tp
   193: 000000000000fec0   885 FUNC    GLOBAL DEFAULT   12 stp_dkg_start_stp
   194: 000000000000fe90     9 FUNC    GLOBAL DEFAULT   12 stp_dkg_stpstate_sessionid
   195: 0000000000010240   149 FUNC    GLOBAL DEFAULT   12 stp_dkg_stp_set_bufs
   196: 000000000001c100    33 FUNC    GLOBAL DEFAULT   12 toprf_update_peerstate_share
   197: 00000000000084a0   233 FUNC    GLOBAL DEFAULT   12 tpdkg_tp_input_size
   198: 00000000000077e0  1020 FUNC    GLOBAL DEFAULT   12 dkg_vss_reconstruct
   199: 0000000000010a00   334 FUNC    GLOBAL DEFAULT   12 stp_dkg_stp_output_size
   200: 0000000000012bf0  8491 FUNC    GLOBAL DEFAULT   12 stp_dkg_peer_next
   201: 0000000000005de0   348 FUNC    GLOBAL DEFAULT   12 toprf_3hashtdh
   202: 000000000001d620   770 FUNC    GLOBAL DEFAULT   12 toprf_update_peer_output_size
   203: 000000000001b5c0     7 FUNC    GLOBAL DEFAULT   12 toprf_update_peerstate_step
   204: 0000000000010b50   863 FUNC    GLOBAL DEFAULT   12 stp_dkg_stp_peer_msg
   205: 0000000000007560   287 FUNC    GLOBAL DEFAULT   12 dkg_vss_verify_commitments
   206: 0000000000024cd0    14 FUNC    GLOBAL DEFAULT   12 crypto_kdf_hkdf_sha256_keygen
   207: 000000000000b480  6299 FUNC    GLOBAL DEFAULT   12 tpdkg_peer_next
   208: 0000000000011260  6541 FUNC    GLOBAL DEFAULT   12 stp_dkg_stp_next
   209: 000000000001b620     7 FUNC    GLOBAL DEFAULT   12 toprf_update_stpstate_step
   210: 0000000000006d70   284 FUNC    GLOBAL DEFAULT   12 dkg_noise_encrypt
   211: 000000000001b590     9 FUNC    GLOBAL DEFAULT   12 toprf_update_peerstate_n
   212: 0000000000006070   361 FUNC    GLOBAL DEFAULT   12 dkg_start
   213: 000000000001c7f0   249 FUNC    GLOBAL DEFAULT   12 toprf_update_stp_input_size
   214: 000000000001dba0 10380 FUNC    GLOBAL DEFAULT   12 toprf_update_stp_next
   215: 0000000000004980     9 FUNC    GLOBAL DEFAULT   12 oprf_KeyGen
   216: 0000000000008ae0   163 FUNC    GLOBAL DEFAULT   12 tpdkg_peer_set_bufs
   217: 000000000001c190   117 FUNC    GLOBAL DEFAULT   12 toprf_update_peer_free
   218: 0000000000006bf0   383 FUNC    GLOBAL DEFAULT   12 dkg_finish_noise_handshake
   219: 000000000001b610     9 FUNC    GLOBAL DEFAULT   12 toprf_update_stpstate_sessionid
   220: 0000000000008ff0   533 FUNC    GLOBAL DEFAULT   12 tpdkg_start_peer
   221: 000000000001b5a0     9 FUNC    GLOBAL DEFAULT   12 toprf_update_peerstate_t
   222: 0000000000008ba0    13 FUNC    GLOBAL DEFAULT   12 tpdkg_peer_not_done
   223: 0000000000007150   182 FUNC    GLOBAL DEFAULT   12 dkg_dump_msg
   224: 000000000000cd20   879 FUNC    GLOBAL DEFAULT   12 tpdkg_cheater_msg
   225: 000000000000fe50    10 FUNC    GLOBAL DEFAULT   12 stp_dkg_stpstate_size
   226: 0000000000007000    61 FUNC    GLOBAL DEFAULT   12 Noise_XK_session_get_key


Dynamic section at offset 0x2d9c8 contains 29 entries:
  Tag        Type                         Name/Value
 0x0000000000000001 (NEEDED)             Shared library: [liboprf-noiseXK.so.0]
 0x0000000000000001 (NEEDED)             Shared library: [libsodium.so.23]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
 0x000000000000000e (SONAME)             Library soname: [liboprf.so.0]
 0x000000000000000c (INIT)               0x4000
 0x000000000000000d (FINI)               0x250a4
 0x0000000000000019 (INIT_ARRAY)         0x2e9b8
 0x000000000000001b (INIT_ARRAYSZ)       8 (bytes)
 0x000000000000001a (FINI_ARRAY)         0x2e9c0
 0x000000000000001c (FINI_ARRAYSZ)       8 (bytes)
 0x000000006ffffef5 (GNU_HASH)           0x260
 0x0000000000000005 (STRTAB)             0x1cb0
 0x0000000000000006 (SYMTAB)             0x768
 0x000000000000000a (STRSZ)              4981 (bytes)
 0x000000000000000b (SYMENT)             24 (bytes)
 0x0000000000000003 (PLTGOT)             0x2ebd8
 0x0000000000000002 (PLTRELSZ)           2928 (bytes)
 0x0000000000000014 (PLTREL)             RELA
 0x0000000000000017 (JMPREL)             0x3348
 0x0000000000000007 (RELA)               0x3240
 0x0000000000000008 (RELASZ)             264 (bytes)
 0x0000000000000009 (RELAENT)            24 (bytes)
 0x000000000000001e (FLAGS)              BIND_NOW
 0x000000006ffffffb (FLAGS_1)            Flags: NOW
 0x000000006ffffffe (VERNEED)            0x31f0
 0x000000006fffffff (VERNEEDNUM)         1
 0x000000006ffffff0 (VERSYM)             0x3026
 0x000000006ffffff9 (RELACOUNT)          3
 0x0000000000000000 (NULL)               0x0

Most of the Noise_XK_ entries are marked with UND now and that is good. Some private functions are still in the export list, and Noise_XK_session_get_key is still in the export list.

[flynn162]

Just tried this:

When I put __attribute__((visibility("hidden"))) in the C files (not the header files), the library will compile and private symbols will not appear in the .dynsym table.

I did not put the attribute in header files because a) I don't want to pollute them with unnecessary stuff b) on the client side, it could be interpreted as a "dll export" directive just like what happened with the protected visibility.

diff --git a/src/dkg-vss.c b/src/dkg-vss.c
index 821355c..719d318 100644
--- a/src/dkg-vss.c
+++ b/src/dkg-vss.c
@@ -7,7 +7,7 @@
 
 // nothing up my sleeve generator H, generated with:
 // hash_to_group((uint8_t*)"DKG Generator H on ristretto255", 32, H)
-const uint8_t H[crypto_core_ristretto255_BYTES]= {
+const __attribute__((visibility("hidden"))) uint8_t H[crypto_core_ristretto255_BYTES]= {
   0x66, 0x4e, 0x4c, 0xb5, 0x89, 0x0e, 0xb3, 0xe4,
   0xc0, 0xd5, 0x48, 0x02, 0x74, 0x8a, 0xb2, 0x25,
   0xf9, 0x73, 0xda, 0xe5, 0xc0, 0xef, 0xc1, 0x68,
diff --git a/src/utils.c b/src/utils.c
index 41a03eb..f4e7f71 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -26,7 +26,7 @@ void debian_rng_scalar(uint8_t *scalar) {
 }
 #endif
 
-void dump(const uint8_t *p, const size_t len, const char* msg, ...) {
+void __attribute__((visibility("hidden"))) dump(const uint8_t *p, const size_t len, const char* msg, ...) {
   FILE* lf = stderr;
   if(!debug) return;
   if(log_file!=NULL) lf = log_file;
@@ -41,7 +41,7 @@ void dump(const uint8_t *p, const size_t len, const char* msg, ...) {
   fflush(lf);
 }
 
-void fail(const char* msg, ...) {
+void __attribute__((visibility("hidden"))) fail(const char* msg, ...) {
   va_list args;
   va_start(args, msg);
   fprintf(stderr, "\x1b[0;31m");

[stef]

Most of the Noise_XK_ entries are marked with UND now and that is good. Some private functions are still in the export list, and Noise_XK_session_get_key is still in the export list.

Noise_XK is a vendored (and sodiumized) version of Noise* - as said, i'm not gonna do much on that corner. however Noise_XK_session_get_key() is a function that has been added by me, it is needed for the robustness of the dkg/update protos. this we can hide away.

i'm gonna have a look what else we can hide. i suppose "log_file" is also a prominent candidate. ;)

your contribution is much appreciated, thank you!

[stef]

check out #9 - i think it covers it all, or did i forget anything?

[stef]

@flynn162 thank you for reporting and collaborating on this issue! i hope liboprf is gonna be useful for you.