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Refactor HMAC implementations

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Similarly to the cryptohash implementations, this refactors the existing
HMAC code into a single set of APIs that can be plugged with any crypto
libraries PostgreSQL is built with (only OpenSSL currently).  If there
is no such libraries, a fallback implementation is available.  Those new
APIs are designed similarly to the existing cryptohash layer, so there
is no real new design here, with the same logic around buffer bound
checks and memory handling.

HMAC has a dependency on cryptohashes, so all the cryptohash types
supported by cryptohash{_openssl}.c can be used with HMAC.  This
refactoring is an advantage mainly for SCRAM, that included its own
implementation of HMAC with SHA256 without relying on the existing
crypto libraries even if PostgreSQL was built with their support.

This code has been tested on Windows and Linux, with and without
OpenSSL, across all the versions supported on HEAD from 1.1.1 down to
1.0.1.  I have also checked that the implementations are working fine
using some sample results, a custom extension of my own, and doing
cross-checks across different major versions with SCRAM with the client
and the backend.

Author: Michael Paquier
Reviewed-by: Bruce Momjian
Discussion: https://postgr.es/m/X9m0nkEJEzIPXjeZ@paquier.xyz
This commit is contained in:
Michael Paquier
2021-04-03 17:30:49 +09:00
parent 1d9c5d0ce2
commit e6bdfd9700
18 changed files with 747 additions and 198 deletions
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71
src/interfaces/libpq/fe-auth-scram.c
View File

@ -15,6 +15,7 @@
#include "postgres_fe.h"
#include "common/base64.h"
#include "common/hmac.h"
#include "common/saslprep.h"
#include "common/scram-common.h"
#include "fe-auth.h"
@ -776,7 +777,11 @@ calculate_client_proof(fe_scram_state *state,
uint8 ClientKey[SCRAM_KEY_LEN];
uint8 ClientSignature[SCRAM_KEY_LEN];
int i;
scram_HMAC_ctx ctx;
pg_hmac_ctx *ctx;
ctx = pg_hmac_create(PG_SHA256);
if (ctx == NULL)
return false;
/*
* Calculate SaltedPassword, and store it in 'state' so that we can reuse
@ -786,26 +791,28 @@ calculate_client_proof(fe_scram_state *state,
state->iterations, state->SaltedPassword) < 0 ||
scram_ClientKey(state->SaltedPassword, ClientKey) < 0 ||
scram_H(ClientKey, SCRAM_KEY_LEN, StoredKey) < 0 ||
scram_HMAC_init(&ctx, StoredKey, SCRAM_KEY_LEN) < 0 ||
scram_HMAC_update(&ctx,
state->client_first_message_bare,
strlen(state->client_first_message_bare)) < 0 ||
scram_HMAC_update(&ctx, ",", 1) < 0 ||
scram_HMAC_update(&ctx,
state->server_first_message,
strlen(state->server_first_message)) < 0 ||
scram_HMAC_update(&ctx, ",", 1) < 0 ||
scram_HMAC_update(&ctx,
client_final_message_without_proof,
strlen(client_final_message_without_proof)) < 0 ||
scram_HMAC_final(ClientSignature, &ctx) < 0)
pg_hmac_init(ctx, StoredKey, SCRAM_KEY_LEN) < 0 ||
pg_hmac_update(ctx,
(uint8 *) state->client_first_message_bare,
strlen(state->client_first_message_bare)) < 0 ||
pg_hmac_update(ctx, (uint8 *) ",", 1) < 0 ||
pg_hmac_update(ctx,
(uint8 *) state->server_first_message,
strlen(state->server_first_message)) < 0 ||
pg_hmac_update(ctx, (uint8 *) ",", 1) < 0 ||
pg_hmac_update(ctx,
(uint8 *) client_final_message_without_proof,
strlen(client_final_message_without_proof)) < 0 ||
pg_hmac_final(ctx, ClientSignature, sizeof(ClientSignature)) < 0)
{
pg_hmac_free(ctx);
return false;
}
for (i = 0; i < SCRAM_KEY_LEN; i++)
result[i] = ClientKey[i] ^ ClientSignature[i];
pg_hmac_free(ctx);
return true;
}
@ -820,27 +827,35 @@ verify_server_signature(fe_scram_state *state, bool *match)
{
uint8 expected_ServerSignature[SCRAM_KEY_LEN];
uint8 ServerKey[SCRAM_KEY_LEN];
scram_HMAC_ctx ctx;
pg_hmac_ctx *ctx;
ctx = pg_hmac_create(PG_SHA256);
if (ctx == NULL)
return false;
if (scram_ServerKey(state->SaltedPassword, ServerKey) < 0 ||
/* calculate ServerSignature */
scram_HMAC_init(&ctx, ServerKey, SCRAM_KEY_LEN) < 0 ||
scram_HMAC_update(&ctx,
state->client_first_message_bare,
strlen(state->client_first_message_bare)) < 0 ||
scram_HMAC_update(&ctx, ",", 1) < 0 ||
scram_HMAC_update(&ctx,
state->server_first_message,
strlen(state->server_first_message)) < 0 ||
scram_HMAC_update(&ctx, ",", 1) < 0 ||
scram_HMAC_update(&ctx,
state->client_final_message_without_proof,
strlen(state->client_final_message_without_proof)) < 0 ||
scram_HMAC_final(expected_ServerSignature, &ctx) < 0)
pg_hmac_init(ctx, ServerKey, SCRAM_KEY_LEN) < 0 ||
pg_hmac_update(ctx,
(uint8 *) state->client_first_message_bare,
strlen(state->client_first_message_bare)) < 0 ||
pg_hmac_update(ctx, (uint8 *) ",", 1) < 0 ||
pg_hmac_update(ctx,
(uint8 *) state->server_first_message,
strlen(state->server_first_message)) < 0 ||
pg_hmac_update(ctx, (uint8 *) ",", 1) < 0 ||
pg_hmac_update(ctx,
(uint8 *) state->client_final_message_without_proof,
strlen(state->client_final_message_without_proof)) < 0 ||
pg_hmac_final(ctx, expected_ServerSignature,
sizeof(expected_ServerSignature)) < 0)
{
pg_hmac_free(ctx);
return false;
}
pg_hmac_free(ctx);
/* signature processed, so now check after it */
if (memcmp(expected_ServerSignature, state->ServerSignature, SCRAM_KEY_LEN) != 0)
*match = false;