SCRAM verifier & md5 credential storage with SCRAM/md5 backend pass-through - PostgreSQL #5865
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,205 @@ | ||
| --- ../tmp/src/interfaces/libpq/libpq-int.h 2026-06-24 03:51:37.037786331 +0500 | ||
| +++ ./src/interfaces/libpq/libpq-int.h 2026-06-24 03:03:14.441153729 +0500 | ||
| @@ -384,6 +384,9 @@ | ||
| char *pgpassfile; /* path to a file containing password(s) */ | ||
| char *channel_binding; /* channel binding mode | ||
| * (require,prefer,disable) */ | ||
| + char *scram_client_key; /* base64 32-byte ClientKey (ProxySQL SCRAM pass-through) */ | ||
| + char *scram_server_key; /* base64 32-byte ServerKey (ProxySQL SCRAM pass-through) */ | ||
| + char *md5_secret; /* stored "md5"+32hex to reuse for backend md5 auth */ | ||
| char *keepalives; /* use TCP keepalives? */ | ||
| char *keepalives_idle; /* time between TCP keepalives */ | ||
| char *keepalives_interval; /* time between TCP keepalive | ||
| --- ../tmp/src/interfaces/libpq/fe-connect.c 2026-06-24 03:51:37.040811504 +0500 | ||
| +++ ./src/interfaces/libpq/fe-connect.c 2026-06-24 03:04:47.178883449 +0500 | ||
| @@ -361,6 +361,18 @@ | ||
| "Load-Balance-Hosts", "", 8, /* sizeof("disable") = 8 */ | ||
| offsetof(struct pg_conn, load_balance_hosts)}, | ||
|
|
||
| + {"scram_client_key", NULL, NULL, NULL, | ||
| + "SCRAM-Client-Key", "*", 64, | ||
| + offsetof(struct pg_conn, scram_client_key)}, | ||
| + | ||
| + {"scram_server_key", NULL, NULL, NULL, | ||
| + "SCRAM-Server-Key", "*", 64, | ||
| + offsetof(struct pg_conn, scram_server_key)}, | ||
| + | ||
| + {"md5_secret", NULL, NULL, NULL, | ||
| + "MD5-Secret", "*", 64, | ||
| + offsetof(struct pg_conn, md5_secret)}, | ||
| + | ||
| /* Terminating entry --- MUST BE LAST */ | ||
| {NULL, NULL, NULL, NULL, | ||
| NULL, NULL, 0} | ||
| @@ -4436,6 +4436,22 @@ | ||
| } | ||
| free(conn->pgpassfile); | ||
| free(conn->channel_binding); | ||
| + /* ProxySQL SCRAM/md5 verifier pass-through: free + scrub the injected key material. */ | ||
| + if (conn->scram_client_key) | ||
| + { | ||
| + explicit_bzero(conn->scram_client_key, strlen(conn->scram_client_key)); | ||
| + free(conn->scram_client_key); | ||
| + } | ||
| + if (conn->scram_server_key) | ||
| + { | ||
| + explicit_bzero(conn->scram_server_key, strlen(conn->scram_server_key)); | ||
| + free(conn->scram_server_key); | ||
| + } | ||
| + if (conn->md5_secret) | ||
| + { | ||
| + explicit_bzero(conn->md5_secret, strlen(conn->md5_secret)); | ||
| + free(conn->md5_secret); | ||
| + } | ||
| free(conn->keepalives); | ||
| free(conn->keepalives_idle); | ||
| free(conn->keepalives_interval); | ||
| --- ../tmp/src/interfaces/libpq/fe-auth-scram.c 2026-06-24 03:51:37.041568997 +0500 | ||
| +++ ./src/interfaces/libpq/fe-auth-scram.c 2026-06-24 03:08:23.927939654 +0500 | ||
| @@ -120,6 +120,29 @@ | ||
| return NULL; | ||
| } | ||
|
|
||
| + /* | ||
| + * ProxySQL SCRAM pass-through: when a ClientKey is injected the exchange | ||
| + * uses it instead of a password. Require BOTH ClientKey and ServerKey (or | ||
| + * neither), so mutual authentication can never be silently skipped. | ||
| + */ | ||
| + { | ||
| + bool has_ck = (conn->scram_client_key && conn->scram_client_key[0]); | ||
| + bool has_sk = (conn->scram_server_key && conn->scram_server_key[0]); | ||
| + | ||
| + if (has_ck != has_sk) | ||
| + { | ||
| + free(state->sasl_mechanism); | ||
| + free(state); | ||
| + return NULL; | ||
| + } | ||
| + if (has_ck) | ||
| + { | ||
| + /* No password to normalize; keys are injected. */ | ||
| + state->password = NULL; | ||
| + return state; | ||
| + } | ||
| + } | ||
| + | ||
| /* Normalize the password with SASLprep, if possible */ | ||
| rc = pg_saslprep(password, &prep_password); | ||
| if (rc == SASLPREP_OOM) | ||
| @@ -785,14 +808,37 @@ | ||
| * Calculate SaltedPassword, and store it in 'state' so that we can reuse | ||
| * it later in verify_server_signature. | ||
| */ | ||
| - if (scram_SaltedPassword(state->password, state->hash_type, | ||
| - state->key_length, state->salt, state->saltlen, | ||
| - state->iterations, state->SaltedPassword, | ||
| - errstr) < 0 || | ||
| - scram_ClientKey(state->SaltedPassword, state->hash_type, | ||
| - state->key_length, ClientKey, errstr) < 0 || | ||
| - scram_H(ClientKey, state->hash_type, state->key_length, | ||
| - StoredKey, errstr) < 0) | ||
| + if (state->conn->scram_client_key && state->conn->scram_client_key[0]) | ||
| + { | ||
| + /* | ||
| + * ProxySQL SCRAM pass-through: use the injected ClientKey directly and | ||
| + * derive StoredKey = SHA256(ClientKey). Skips SASLprep + PBKDF2. | ||
| + */ | ||
| + int dec = pg_b64_decode(state->conn->scram_client_key, | ||
| + strlen(state->conn->scram_client_key), | ||
| + (char *) ClientKey, state->key_length); | ||
| + | ||
| + if (dec != state->key_length) | ||
| + { | ||
| + *errstr = "invalid scram_client_key"; | ||
| + pg_hmac_free(ctx); | ||
| + return false; | ||
| + } | ||
| + if (scram_H(ClientKey, state->hash_type, state->key_length, | ||
| + StoredKey, errstr) < 0) | ||
| + { | ||
| + pg_hmac_free(ctx); | ||
| + return false; | ||
| + } | ||
| + } | ||
| + else if (scram_SaltedPassword(state->password, state->hash_type, | ||
| + state->key_length, state->salt, state->saltlen, | ||
| + state->iterations, state->SaltedPassword, | ||
| + errstr) < 0 || | ||
| + scram_ClientKey(state->SaltedPassword, state->hash_type, | ||
| + state->key_length, ClientKey, errstr) < 0 || | ||
| + scram_H(ClientKey, state->hash_type, state->key_length, | ||
| + StoredKey, errstr) < 0) | ||
| { | ||
| /* errstr is already filled here */ | ||
| pg_hmac_free(ctx); | ||
| @@ -847,8 +893,22 @@ | ||
| return false; | ||
| } | ||
|
|
||
| - if (scram_ServerKey(state->SaltedPassword, state->hash_type, | ||
| - state->key_length, ServerKey, errstr) < 0) | ||
| + if (state->conn->scram_server_key && state->conn->scram_server_key[0]) | ||
| + { | ||
| + /* ProxySQL SCRAM pass-through: verify with the injected ServerKey. */ | ||
| + int dec = pg_b64_decode(state->conn->scram_server_key, | ||
| + strlen(state->conn->scram_server_key), | ||
| + (char *) ServerKey, state->key_length); | ||
| + | ||
| + if (dec != state->key_length) | ||
| + { | ||
| + *errstr = "invalid scram_server_key"; | ||
| + pg_hmac_free(ctx); | ||
| + return false; | ||
| + } | ||
| + } | ||
| + else if (scram_ServerKey(state->SaltedPassword, state->hash_type, | ||
| + state->key_length, ServerKey, errstr) < 0) | ||
| { | ||
| /* errstr is filled already */ | ||
| pg_hmac_free(ctx); | ||
| --- ../tmp/src/interfaces/libpq/fe-auth.c 2026-06-24 03:51:37.042103163 +0500 | ||
| +++ ./src/interfaces/libpq/fe-auth.c 2026-06-24 03:08:34.430125390 +0500 | ||
| @@ -553,7 +553,8 @@ | ||
| password = conn->connhost[conn->whichhost].password; | ||
| if (password == NULL) | ||
| password = conn->pgpass; | ||
| - if (password == NULL || password[0] == '\0') | ||
| + if ((password == NULL || password[0] == '\0') && | ||
| + !(conn->scram_client_key && conn->scram_client_key[0])) | ||
| { | ||
| appendPQExpBufferStr(&conn->errorMessage, | ||
| PQnoPasswordSupplied); | ||
| @@ -731,9 +732,20 @@ | ||
| } | ||
|
|
||
| crypt_pwd2 = crypt_pwd + MD5_PASSWD_LEN + 1; | ||
| - if (!pg_md5_encrypt(password, conn->pguser, | ||
| - strlen(conn->pguser), crypt_pwd2, | ||
| - &errstr)) | ||
| + if (conn->md5_secret && conn->md5_secret[0]) | ||
| + { | ||
| + /* ProxySQL: reuse the stored md5 secret as the inner hash. */ | ||
| + if (strlen(conn->md5_secret) != MD5_PASSWD_LEN) | ||
| + { | ||
| + libpq_append_conn_error(conn, "invalid md5_secret"); | ||
| + free(crypt_pwd); | ||
| + return STATUS_ERROR; | ||
| + } | ||
| + strcpy(crypt_pwd2, conn->md5_secret); | ||
| + } | ||
| + else if (!pg_md5_encrypt(password, conn->pguser, | ||
| + strlen(conn->pguser), crypt_pwd2, | ||
| + &errstr)) | ||
| { | ||
| libpq_append_conn_error(conn, "could not encrypt password: %s", errstr); | ||
| free(crypt_pwd); | ||
| @@ -1096,7 +1108,8 @@ | ||
| password = conn->connhost[conn->whichhost].password; | ||
| if (password == NULL) | ||
| password = conn->pgpass; | ||
| - if (password == NULL || password[0] == '\0') | ||
| + if ((password == NULL || password[0] == '\0') && | ||
| + !(conn->md5_secret && conn->md5_secret[0])) | ||
| { | ||
| appendPQExpBufferStr(&conn->errorMessage, | ||
| PQnoPasswordSupplied); |
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🔒 Security & Privacy | 🟠 Major | 🏗️ Heavy lift
Invalidate pooled backends when SCRAM credentials rotate.
Preserving the existing reuse semantics leaves the confirmed case where an A-era backend connection can serve after verifier B is loaded. Include a credential generation/fingerprint in pool matching and evict mismatched idle connections during credential reload; otherwise rotation or revocation does not take effect.
🤖 Prompt for AI Agents