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auth-scram.c File Reference
#include "postgres.h"
#include <unistd.h>
#include "access/xlog.h"
#include "catalog/pg_control.h"
#include "common/base64.h"
#include "common/hmac.h"
#include "common/saslprep.h"
#include "common/scram-common.h"
#include "common/sha2.h"
#include "libpq/crypt.h"
#include "libpq/sasl.h"
#include "libpq/scram.h"
Include dependency graph for auth-scram.c:

Go to the source code of this file.

Data Structures

struct  scram_state
 

Enumerations

enum  scram_state_enum { SCRAM_AUTH_INIT , SCRAM_AUTH_SALT_SENT , SCRAM_AUTH_FINISHED }
 

Functions

static void scram_get_mechanisms (Port *port, StringInfo buf)
 
static void * scram_init (Port *port, const char *selected_mech, const char *shadow_pass)
 
static int scram_exchange (void *opaq, const char *input, int inputlen, char **output, int *outputlen, const char **logdetail)
 
static void read_client_first_message (scram_state *state, const char *input)
 
static void read_client_final_message (scram_state *state, const char *input)
 
static char * build_server_first_message (scram_state *state)
 
static char * build_server_final_message (scram_state *state)
 
static bool verify_client_proof (scram_state *state)
 
static bool verify_final_nonce (scram_state *state)
 
static void mock_scram_secret (const char *username, pg_cryptohash_type *hash_type, int *iterations, int *key_length, char **salt, uint8 *stored_key, uint8 *server_key)
 
static bool is_scram_printable (char *p)
 
static char * sanitize_char (char c)
 
static char * sanitize_str (const char *s)
 
static char * scram_mock_salt (const char *username, pg_cryptohash_type hash_type, int key_length)
 
char * pg_be_scram_build_secret (const char *password)
 
bool scram_verify_plain_password (const char *username, const char *password, const char *secret)
 
bool parse_scram_secret (const char *secret, int *iterations, pg_cryptohash_type *hash_type, int *key_length, char **salt, uint8 *stored_key, uint8 *server_key)
 
static char * read_attr_value (char **input, char attr)
 
static char * read_any_attr (char **input, char *attr_p)
 

Variables

const pg_be_sasl_mech pg_be_scram_mech
 
int scram_sha_256_iterations = SCRAM_SHA_256_DEFAULT_ITERATIONS
 

Enumeration Type Documentation

◆ scram_state_enum

Enumerator
SCRAM_AUTH_INIT 
SCRAM_AUTH_SALT_SENT 
SCRAM_AUTH_FINISHED 

Definition at line 125 of file auth-scram.c.

126 {
scram_state_enum
Definition: auth-scram.c:126
@ SCRAM_AUTH_SALT_SENT
Definition: auth-scram.c:128
@ SCRAM_AUTH_FINISHED
Definition: auth-scram.c:129
@ SCRAM_AUTH_INIT
Definition: auth-scram.c:127

Function Documentation

◆ build_server_final_message()

static char * build_server_final_message ( scram_state state)
static

Definition at line 1404 of file auth-scram.c.

1405 {
1406  uint8 ServerSignature[SCRAM_MAX_KEY_LEN];
1407  char *server_signature_base64;
1408  int siglen;
1409  pg_hmac_ctx *ctx = pg_hmac_create(state->hash_type);
1410 
1411  /* calculate ServerSignature */
1412  if (pg_hmac_init(ctx, state->ServerKey, state->key_length) < 0 ||
1413  pg_hmac_update(ctx,
1414  (uint8 *) state->client_first_message_bare,
1415  strlen(state->client_first_message_bare)) < 0 ||
1416  pg_hmac_update(ctx, (uint8 *) ",", 1) < 0 ||
1417  pg_hmac_update(ctx,
1418  (uint8 *) state->server_first_message,
1419  strlen(state->server_first_message)) < 0 ||
1420  pg_hmac_update(ctx, (uint8 *) ",", 1) < 0 ||
1421  pg_hmac_update(ctx,
1422  (uint8 *) state->client_final_message_without_proof,
1423  strlen(state->client_final_message_without_proof)) < 0 ||
1424  pg_hmac_final(ctx, ServerSignature, state->key_length) < 0)
1425  {
1426  elog(ERROR, "could not calculate server signature: %s",
1427  pg_hmac_error(ctx));
1428  }
1429 
1430  pg_hmac_free(ctx);
1431 
1432  siglen = pg_b64_enc_len(state->key_length);
1433  /* don't forget the zero-terminator */
1434  server_signature_base64 = palloc(siglen + 1);
1435  siglen = pg_b64_encode((const char *) ServerSignature,
1436  state->key_length, server_signature_base64,
1437  siglen);
1438  if (siglen < 0)
1439  elog(ERROR, "could not encode server signature");
1440  server_signature_base64[siglen] = '\0';
1441 
1442  /*------
1443  * The syntax for the server-final-message is: (RFC 5802)
1444  *
1445  * verifier = "v=" base64
1446  * ;; base-64 encoded ServerSignature.
1447  *
1448  * server-final-message = (server-error / verifier)
1449  * ["," extensions]
1450  *
1451  *------
1452  */
1453  return psprintf("v=%s", server_signature_base64);
1454 }
int pg_b64_enc_len(int srclen)
Definition: base64.c:224
int pg_b64_encode(const char *src, int len, char *dst, int dstlen)
Definition: base64.c:49
unsigned char uint8
Definition: c.h:490
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:225
pg_hmac_ctx * pg_hmac_create(pg_cryptohash_type type)
Definition: hmac.c:77
const char * pg_hmac_error(pg_hmac_ctx *ctx)
Definition: hmac.c:306
void pg_hmac_free(pg_hmac_ctx *ctx)
Definition: hmac.c:289
int pg_hmac_update(pg_hmac_ctx *ctx, const uint8 *data, size_t len)
Definition: hmac.c:223
int pg_hmac_init(pg_hmac_ctx *ctx, const uint8 *key, size_t len)
Definition: hmac.c:138
int pg_hmac_final(pg_hmac_ctx *ctx, uint8 *dest, size_t len)
Definition: hmac.c:244
void * palloc(Size size)
Definition: mcxt.c:1317
char * psprintf(const char *fmt,...)
Definition: psprintf.c:43
#define SCRAM_MAX_KEY_LEN
Definition: scram-common.h:30
Definition: regguts.h:323

References elog, ERROR, palloc(), pg_b64_enc_len(), pg_b64_encode(), pg_hmac_create(), pg_hmac_error(), pg_hmac_final(), pg_hmac_free(), pg_hmac_init(), pg_hmac_update(), psprintf(), and SCRAM_MAX_KEY_LEN.

Referenced by scram_exchange().

◆ build_server_first_message()

static char * build_server_first_message ( scram_state state)
static

Definition at line 1194 of file auth-scram.c.

1195 {
1196  /*------
1197  * The syntax for the server-first-message is: (RFC 5802)
1198  *
1199  * server-first-message =
1200  * [reserved-mext ","] nonce "," salt ","
1201  * iteration-count ["," extensions]
1202  *
1203  * nonce = "r=" c-nonce [s-nonce]
1204  * ;; Second part provided by server.
1205  *
1206  * c-nonce = printable
1207  *
1208  * s-nonce = printable
1209  *
1210  * salt = "s=" base64
1211  *
1212  * iteration-count = "i=" posit-number
1213  * ;; A positive number.
1214  *
1215  * Example:
1216  *
1217  * r=fyko+d2lbbFgONRv9qkxdawL3rfcNHYJY1ZVvWVs7j,s=QSXCR+Q6sek8bf92,i=4096
1218  *------
1219  */
1220 
1221  /*
1222  * Per the spec, the nonce may consist of any printable ASCII characters.
1223  * For convenience, however, we don't use the whole range available,
1224  * rather, we generate some random bytes, and base64 encode them.
1225  */
1226  char raw_nonce[SCRAM_RAW_NONCE_LEN];
1227  int encoded_len;
1228 
1229  if (!pg_strong_random(raw_nonce, SCRAM_RAW_NONCE_LEN))
1230  ereport(ERROR,
1231  (errcode(ERRCODE_INTERNAL_ERROR),
1232  errmsg("could not generate random nonce")));
1233 
1234  encoded_len = pg_b64_enc_len(SCRAM_RAW_NONCE_LEN);
1235  /* don't forget the zero-terminator */
1236  state->server_nonce = palloc(encoded_len + 1);
1237  encoded_len = pg_b64_encode(raw_nonce, SCRAM_RAW_NONCE_LEN,
1238  state->server_nonce, encoded_len);
1239  if (encoded_len < 0)
1240  ereport(ERROR,
1241  (errcode(ERRCODE_INTERNAL_ERROR),
1242  errmsg("could not encode random nonce")));
1243  state->server_nonce[encoded_len] = '\0';
1244 
1245  state->server_first_message =
1246  psprintf("r=%s%s,s=%s,i=%d",
1247  state->client_nonce, state->server_nonce,
1248  state->salt, state->iterations);
1249 
1250  return pstrdup(state->server_first_message);
1251 }
int errcode(int sqlerrcode)
Definition: elog.c:853
int errmsg(const char *fmt,...)
Definition: elog.c:1070
#define ereport(elevel,...)
Definition: elog.h:149
char * pstrdup(const char *in)
Definition: mcxt.c:1696
bool pg_strong_random(void *buf, size_t len)
#define SCRAM_RAW_NONCE_LEN
Definition: scram-common.h:37

References ereport, errcode(), errmsg(), ERROR, palloc(), pg_b64_enc_len(), pg_b64_encode(), pg_strong_random(), psprintf(), pstrdup(), and SCRAM_RAW_NONCE_LEN.

Referenced by scram_exchange().

◆ is_scram_printable()

static bool is_scram_printable ( char *  p)
static

Definition at line 770 of file auth-scram.c.

771 {
772  /*------
773  * Printable characters, as defined by SCRAM spec: (RFC 5802)
774  *
775  * printable = %x21-2B / %x2D-7E
776  * ;; Printable ASCII except ",".
777  * ;; Note that any "printable" is also
778  * ;; a valid "value".
779  *------
780  */
781  for (; *p; p++)
782  {
783  if (*p < 0x21 || *p > 0x7E || *p == 0x2C /* comma */ )
784  return false;
785  }
786  return true;
787 }

Referenced by read_client_first_message().

◆ mock_scram_secret()

static void mock_scram_secret ( const char *  username,
pg_cryptohash_type hash_type,
int *  iterations,
int *  key_length,
char **  salt,
uint8 stored_key,
uint8 server_key 
)
static

Definition at line 688 of file auth-scram.c.

691 {
692  char *raw_salt;
693  char *encoded_salt;
694  int encoded_len;
695 
696  /* Enforce the use of SHA-256, which would be realistic enough */
697  *hash_type = PG_SHA256;
698  *key_length = SCRAM_SHA_256_KEY_LEN;
699 
700  /*
701  * Generate deterministic salt.
702  *
703  * Note that we cannot reveal any information to an attacker here so the
704  * error messages need to remain generic. This should never fail anyway
705  * as the salt generated for mock authentication uses the cluster's nonce
706  * value.
707  */
708  raw_salt = scram_mock_salt(username, *hash_type, *key_length);
709  if (raw_salt == NULL)
710  elog(ERROR, "could not encode salt");
711 
712  encoded_len = pg_b64_enc_len(SCRAM_DEFAULT_SALT_LEN);
713  /* don't forget the zero-terminator */
714  encoded_salt = (char *) palloc(encoded_len + 1);
715  encoded_len = pg_b64_encode(raw_salt, SCRAM_DEFAULT_SALT_LEN, encoded_salt,
716  encoded_len);
717 
718  if (encoded_len < 0)
719  elog(ERROR, "could not encode salt");
720  encoded_salt[encoded_len] = '\0';
721 
722  *salt = encoded_salt;
724 
725  /* StoredKey and ServerKey are not used in a doomed authentication */
726  memset(stored_key, 0, SCRAM_MAX_KEY_LEN);
727  memset(server_key, 0, SCRAM_MAX_KEY_LEN);
728 }
static char * scram_mock_salt(const char *username, pg_cryptohash_type hash_type, int key_length)
Definition: auth-scram.c:1463
@ PG_SHA256
Definition: cryptohash.h:24
static char * username
Definition: initdb.c:153
#define SCRAM_DEFAULT_SALT_LEN
Definition: scram-common.h:44
#define SCRAM_SHA_256_KEY_LEN
Definition: scram-common.h:24
#define SCRAM_SHA_256_DEFAULT_ITERATIONS
Definition: scram-common.h:50
int iterations
Definition: thread-thread.c:39

References elog, ERROR, iterations, palloc(), pg_b64_enc_len(), pg_b64_encode(), PG_SHA256, SCRAM_DEFAULT_SALT_LEN, SCRAM_MAX_KEY_LEN, scram_mock_salt(), SCRAM_SHA_256_DEFAULT_ITERATIONS, SCRAM_SHA_256_KEY_LEN, and username.

Referenced by scram_init().

◆ parse_scram_secret()

bool parse_scram_secret ( const char *  secret,
int *  iterations,
pg_cryptohash_type hash_type,
int *  key_length,
char **  salt,
uint8 stored_key,
uint8 server_key 
)

Definition at line 591 of file auth-scram.c.

594 {
595  char *v;
596  char *p;
597  char *scheme_str;
598  char *salt_str;
599  char *iterations_str;
600  char *storedkey_str;
601  char *serverkey_str;
602  int decoded_len;
603  char *decoded_salt_buf;
604  char *decoded_stored_buf;
605  char *decoded_server_buf;
606 
607  /*
608  * The secret is of form:
609  *
610  * SCRAM-SHA-256$<iterations>:<salt>$<storedkey>:<serverkey>
611  */
612  v = pstrdup(secret);
613  scheme_str = strsep(&v, "$");
614  if (v == NULL)
615  goto invalid_secret;
616  iterations_str = strsep(&v, ":");
617  if (v == NULL)
618  goto invalid_secret;
619  salt_str = strsep(&v, "$");
620  if (v == NULL)
621  goto invalid_secret;
622  storedkey_str = strsep(&v, ":");
623  if (v == NULL)
624  goto invalid_secret;
625  serverkey_str = v;
626 
627  /* Parse the fields */
628  if (strcmp(scheme_str, "SCRAM-SHA-256") != 0)
629  goto invalid_secret;
630  *hash_type = PG_SHA256;
631  *key_length = SCRAM_SHA_256_KEY_LEN;
632 
633  errno = 0;
634  *iterations = strtol(iterations_str, &p, 10);
635  if (*p || errno != 0)
636  goto invalid_secret;
637 
638  /*
639  * Verify that the salt is in Base64-encoded format, by decoding it,
640  * although we return the encoded version to the caller.
641  */
642  decoded_len = pg_b64_dec_len(strlen(salt_str));
643  decoded_salt_buf = palloc(decoded_len);
644  decoded_len = pg_b64_decode(salt_str, strlen(salt_str),
645  decoded_salt_buf, decoded_len);
646  if (decoded_len < 0)
647  goto invalid_secret;
648  *salt = pstrdup(salt_str);
649 
650  /*
651  * Decode StoredKey and ServerKey.
652  */
653  decoded_len = pg_b64_dec_len(strlen(storedkey_str));
654  decoded_stored_buf = palloc(decoded_len);
655  decoded_len = pg_b64_decode(storedkey_str, strlen(storedkey_str),
656  decoded_stored_buf, decoded_len);
657  if (decoded_len != *key_length)
658  goto invalid_secret;
659  memcpy(stored_key, decoded_stored_buf, *key_length);
660 
661  decoded_len = pg_b64_dec_len(strlen(serverkey_str));
662  decoded_server_buf = palloc(decoded_len);
663  decoded_len = pg_b64_decode(serverkey_str, strlen(serverkey_str),
664  decoded_server_buf, decoded_len);
665  if (decoded_len != *key_length)
666  goto invalid_secret;
667  memcpy(server_key, decoded_server_buf, *key_length);
668 
669  return true;
670 
671 invalid_secret:
672  *salt = NULL;
673  return false;
674 }
int pg_b64_decode(const char *src, int len, char *dst, int dstlen)
Definition: base64.c:116
int pg_b64_dec_len(int srclen)
Definition: base64.c:239
char * strsep(char **stringp, const char *delim)
Definition: strsep.c:49

References iterations, palloc(), pg_b64_dec_len(), pg_b64_decode(), PG_SHA256, pstrdup(), SCRAM_SHA_256_KEY_LEN, and strsep().

Referenced by get_password_type(), scram_init(), and scram_verify_plain_password().

◆ pg_be_scram_build_secret()

char* pg_be_scram_build_secret ( const char *  password)

Definition at line 474 of file auth-scram.c.

475 {
476  char *prep_password;
477  pg_saslprep_rc rc;
478  char saltbuf[SCRAM_DEFAULT_SALT_LEN];
479  char *result;
480  const char *errstr = NULL;
481 
482  /*
483  * Normalize the password with SASLprep. If that doesn't work, because
484  * the password isn't valid UTF-8 or contains prohibited characters, just
485  * proceed with the original password. (See comments at top of file.)
486  */
487  rc = pg_saslprep(password, &prep_password);
488  if (rc == SASLPREP_SUCCESS)
489  password = (const char *) prep_password;
490 
491  /* Generate random salt */
493  ereport(ERROR,
494  (errcode(ERRCODE_INTERNAL_ERROR),
495  errmsg("could not generate random salt")));
496 
498  saltbuf, SCRAM_DEFAULT_SALT_LEN,
500  &errstr);
501 
502  if (prep_password)
503  pfree(prep_password);
504 
505  return result;
506 }
int scram_sha_256_iterations
Definition: auth-scram.c:194
void pfree(void *pointer)
Definition: mcxt.c:1521
pg_saslprep_rc pg_saslprep(const char *input, char **output)
Definition: saslprep.c:1047
pg_saslprep_rc
Definition: saslprep.h:21
@ SASLPREP_SUCCESS
Definition: saslprep.h:22
char * scram_build_secret(pg_cryptohash_type hash_type, int key_length, const char *salt, int saltlen, int iterations, const char *password, const char **errstr)
Definition: scram-common.c:210
static char * password
Definition: streamutil.c:52

References ereport, errcode(), errmsg(), ERROR, password, pfree(), pg_saslprep(), PG_SHA256, pg_strong_random(), SASLPREP_SUCCESS, scram_build_secret(), SCRAM_DEFAULT_SALT_LEN, scram_sha_256_iterations, and SCRAM_SHA_256_KEY_LEN.

Referenced by encrypt_password().

◆ read_any_attr()

static char* read_any_attr ( char **  input,
char *  attr_p 
)
static

Definition at line 846 of file auth-scram.c.

847 {
848  char *begin = *input;
849  char *end;
850  char attr = *begin;
851 
852  if (attr == '\0')
853  ereport(ERROR,
854  (errcode(ERRCODE_PROTOCOL_VIOLATION),
855  errmsg("malformed SCRAM message"),
856  errdetail("Attribute expected, but found end of string.")));
857 
858  /*------
859  * attr-val = ALPHA "=" value
860  * ;; Generic syntax of any attribute sent
861  * ;; by server or client
862  *------
863  */
864  if (!((attr >= 'A' && attr <= 'Z') ||
865  (attr >= 'a' && attr <= 'z')))
866  ereport(ERROR,
867  (errcode(ERRCODE_PROTOCOL_VIOLATION),
868  errmsg("malformed SCRAM message"),
869  errdetail("Attribute expected, but found invalid character \"%s\".",
870  sanitize_char(attr))));
871  if (attr_p)
872  *attr_p = attr;
873  begin++;
874 
875  if (*begin != '=')
876  ereport(ERROR,
877  (errcode(ERRCODE_PROTOCOL_VIOLATION),
878  errmsg("malformed SCRAM message"),
879  errdetail("Expected character \"=\" for attribute \"%c\".", attr)));
880  begin++;
881 
882  end = begin;
883  while (*end && *end != ',')
884  end++;
885 
886  if (*end)
887  {
888  *end = '\0';
889  *input = end + 1;
890  }
891  else
892  *input = end;
893 
894  return begin;
895 }
static char * sanitize_char(char c)
Definition: auth-scram.c:798
int errdetail(const char *fmt,...)
Definition: elog.c:1203
FILE * input

References ereport, errcode(), errdetail(), errmsg(), ERROR, input, and sanitize_char().

Referenced by read_client_final_message(), and read_client_first_message().

◆ read_attr_value()

static char* read_attr_value ( char **  input,
char  attr 
)
static

Definition at line 734 of file auth-scram.c.

735 {
736  char *begin = *input;
737  char *end;
738 
739  if (*begin != attr)
740  ereport(ERROR,
741  (errcode(ERRCODE_PROTOCOL_VIOLATION),
742  errmsg("malformed SCRAM message"),
743  errdetail("Expected attribute \"%c\" but found \"%s\".",
744  attr, sanitize_char(*begin))));
745  begin++;
746 
747  if (*begin != '=')
748  ereport(ERROR,
749  (errcode(ERRCODE_PROTOCOL_VIOLATION),
750  errmsg("malformed SCRAM message"),
751  errdetail("Expected character \"=\" for attribute \"%c\".", attr)));
752  begin++;
753 
754  end = begin;
755  while (*end && *end != ',')
756  end++;
757 
758  if (*end)
759  {
760  *end = '\0';
761  *input = end + 1;
762  }
763  else
764  *input = end;
765 
766  return begin;
767 }

References ereport, errcode(), errdetail(), errmsg(), ERROR, input, and sanitize_char().

Referenced by read_client_final_message(), and read_client_first_message().

◆ read_client_final_message()

static void read_client_final_message ( scram_state state,
const char *  input 
)
static

Definition at line 1258 of file auth-scram.c.

1259 {
1260  char attr;
1261  char *channel_binding;
1262  char *value;
1263  char *begin,
1264  *proof;
1265  char *p;
1266  char *client_proof;
1267  int client_proof_len;
1268 
1269  begin = p = pstrdup(input);
1270 
1271  /*------
1272  * The syntax for the server-first-message is: (RFC 5802)
1273  *
1274  * gs2-header = gs2-cbind-flag "," [ authzid ] ","
1275  * ;; GS2 header for SCRAM
1276  * ;; (the actual GS2 header includes an optional
1277  * ;; flag to indicate that the GSS mechanism is not
1278  * ;; "standard", but since SCRAM is "standard", we
1279  * ;; don't include that flag).
1280  *
1281  * cbind-input = gs2-header [ cbind-data ]
1282  * ;; cbind-data MUST be present for
1283  * ;; gs2-cbind-flag of "p" and MUST be absent
1284  * ;; for "y" or "n".
1285  *
1286  * channel-binding = "c=" base64
1287  * ;; base64 encoding of cbind-input.
1288  *
1289  * proof = "p=" base64
1290  *
1291  * client-final-message-without-proof =
1292  * channel-binding "," nonce [","
1293  * extensions]
1294  *
1295  * client-final-message =
1296  * client-final-message-without-proof "," proof
1297  *------
1298  */
1299 
1300  /*
1301  * Read channel binding. This repeats the channel-binding flags and is
1302  * then followed by the actual binding data depending on the type.
1303  */
1304  channel_binding = read_attr_value(&p, 'c');
1305  if (state->channel_binding_in_use)
1306  {
1307 #ifdef USE_SSL
1308  const char *cbind_data = NULL;
1309  size_t cbind_data_len = 0;
1310  size_t cbind_header_len;
1311  char *cbind_input;
1312  size_t cbind_input_len;
1313  char *b64_message;
1314  int b64_message_len;
1315 
1316  Assert(state->cbind_flag == 'p');
1317 
1318  /* Fetch hash data of server's SSL certificate */
1319  cbind_data = be_tls_get_certificate_hash(state->port,
1320  &cbind_data_len);
1321 
1322  /* should not happen */
1323  if (cbind_data == NULL || cbind_data_len == 0)
1324  elog(ERROR, "could not get server certificate hash");
1325 
1326  cbind_header_len = strlen("p=tls-server-end-point,,"); /* p=type,, */
1327  cbind_input_len = cbind_header_len + cbind_data_len;
1328  cbind_input = palloc(cbind_input_len);
1329  snprintf(cbind_input, cbind_input_len, "p=tls-server-end-point,,");
1330  memcpy(cbind_input + cbind_header_len, cbind_data, cbind_data_len);
1331 
1332  b64_message_len = pg_b64_enc_len(cbind_input_len);
1333  /* don't forget the zero-terminator */
1334  b64_message = palloc(b64_message_len + 1);
1335  b64_message_len = pg_b64_encode(cbind_input, cbind_input_len,
1336  b64_message, b64_message_len);
1337  if (b64_message_len < 0)
1338  elog(ERROR, "could not encode channel binding data");
1339  b64_message[b64_message_len] = '\0';
1340 
1341  /*
1342  * Compare the value sent by the client with the value expected by the
1343  * server.
1344  */
1345  if (strcmp(channel_binding, b64_message) != 0)
1346  ereport(ERROR,
1347  (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
1348  errmsg("SCRAM channel binding check failed")));
1349 #else
1350  /* shouldn't happen, because we checked this earlier already */
1351  elog(ERROR, "channel binding not supported by this build");
1352 #endif
1353  }
1354  else
1355  {
1356  /*
1357  * If we are not using channel binding, the binding data is expected
1358  * to always be "biws", which is "n,," base64-encoded, or "eSws",
1359  * which is "y,,". We also have to check whether the flag is the same
1360  * one that the client originally sent.
1361  */
1362  if (!(strcmp(channel_binding, "biws") == 0 && state->cbind_flag == 'n') &&
1363  !(strcmp(channel_binding, "eSws") == 0 && state->cbind_flag == 'y'))
1364  ereport(ERROR,
1365  (errcode(ERRCODE_PROTOCOL_VIOLATION),
1366  errmsg("unexpected SCRAM channel-binding attribute in client-final-message")));
1367  }
1368 
1369  state->client_final_nonce = read_attr_value(&p, 'r');
1370 
1371  /* ignore optional extensions, read until we find "p" attribute */
1372  do
1373  {
1374  proof = p - 1;
1375  value = read_any_attr(&p, &attr);
1376  } while (attr != 'p');
1377 
1378  client_proof_len = pg_b64_dec_len(strlen(value));
1379  client_proof = palloc(client_proof_len);
1380  if (pg_b64_decode(value, strlen(value), client_proof,
1381  client_proof_len) != state->key_length)
1382  ereport(ERROR,
1383  (errcode(ERRCODE_PROTOCOL_VIOLATION),
1384  errmsg("malformed SCRAM message"),
1385  errdetail("Malformed proof in client-final-message.")));
1386  memcpy(state->ClientProof, client_proof, state->key_length);
1387  pfree(client_proof);
1388 
1389  if (*p != '\0')
1390  ereport(ERROR,
1391  (errcode(ERRCODE_PROTOCOL_VIOLATION),
1392  errmsg("malformed SCRAM message"),
1393  errdetail("Garbage found at the end of client-final-message.")));
1394 
1395  state->client_final_message_without_proof = palloc(proof - begin + 1);
1396  memcpy(state->client_final_message_without_proof, input, proof - begin);
1397  state->client_final_message_without_proof[proof - begin] = '\0';
1398 }
static char * read_attr_value(char **input, char attr)
Definition: auth-scram.c:734
static char * read_any_attr(char **input, char *attr_p)
Definition: auth-scram.c:846
char * be_tls_get_certificate_hash(Port *port, size_t *len)
#define Assert(condition)
Definition: c.h:837
static struct @160 value
#define snprintf
Definition: port.h:238

References Assert, be_tls_get_certificate_hash(), elog, ereport, errcode(), errdetail(), errmsg(), ERROR, input, palloc(), pfree(), pg_b64_dec_len(), pg_b64_decode(), pg_b64_enc_len(), pg_b64_encode(), pstrdup(), read_any_attr(), read_attr_value(), snprintf, and value.

Referenced by scram_exchange().

◆ read_client_first_message()

static void read_client_first_message ( scram_state state,
const char *  input 
)
static

Definition at line 904 of file auth-scram.c.

905 {
906  char *p = pstrdup(input);
907  char *channel_binding_type;
908 
909 
910  /*------
911  * The syntax for the client-first-message is: (RFC 5802)
912  *
913  * saslname = 1*(value-safe-char / "=2C" / "=3D")
914  * ;; Conforms to <value>.
915  *
916  * authzid = "a=" saslname
917  * ;; Protocol specific.
918  *
919  * cb-name = 1*(ALPHA / DIGIT / "." / "-")
920  * ;; See RFC 5056, Section 7.
921  * ;; E.g., "tls-server-end-point" or
922  * ;; "tls-unique".
923  *
924  * gs2-cbind-flag = ("p=" cb-name) / "n" / "y"
925  * ;; "n" -> client doesn't support channel binding.
926  * ;; "y" -> client does support channel binding
927  * ;; but thinks the server does not.
928  * ;; "p" -> client requires channel binding.
929  * ;; The selected channel binding follows "p=".
930  *
931  * gs2-header = gs2-cbind-flag "," [ authzid ] ","
932  * ;; GS2 header for SCRAM
933  * ;; (the actual GS2 header includes an optional
934  * ;; flag to indicate that the GSS mechanism is not
935  * ;; "standard", but since SCRAM is "standard", we
936  * ;; don't include that flag).
937  *
938  * username = "n=" saslname
939  * ;; Usernames are prepared using SASLprep.
940  *
941  * reserved-mext = "m=" 1*(value-char)
942  * ;; Reserved for signaling mandatory extensions.
943  * ;; The exact syntax will be defined in
944  * ;; the future.
945  *
946  * nonce = "r=" c-nonce [s-nonce]
947  * ;; Second part provided by server.
948  *
949  * c-nonce = printable
950  *
951  * client-first-message-bare =
952  * [reserved-mext ","]
953  * username "," nonce ["," extensions]
954  *
955  * client-first-message =
956  * gs2-header client-first-message-bare
957  *
958  * For example:
959  * n,,n=user,r=fyko+d2lbbFgONRv9qkxdawL
960  *
961  * The "n,," in the beginning means that the client doesn't support
962  * channel binding, and no authzid is given. "n=user" is the username.
963  * However, in PostgreSQL the username is sent in the startup packet, and
964  * the username in the SCRAM exchange is ignored. libpq always sends it
965  * as an empty string. The last part, "r=fyko+d2lbbFgONRv9qkxdawL" is
966  * the client nonce.
967  *------
968  */
969 
970  /*
971  * Read gs2-cbind-flag. (For details see also RFC 5802 Section 6 "Channel
972  * Binding".)
973  */
974  state->cbind_flag = *p;
975  switch (*p)
976  {
977  case 'n':
978 
979  /*
980  * The client does not support channel binding or has simply
981  * decided to not use it. In that case just let it go.
982  */
983  if (state->channel_binding_in_use)
984  ereport(ERROR,
985  (errcode(ERRCODE_PROTOCOL_VIOLATION),
986  errmsg("malformed SCRAM message"),
987  errdetail("The client selected SCRAM-SHA-256-PLUS, but the SCRAM message does not include channel binding data.")));
988 
989  p++;
990  if (*p != ',')
991  ereport(ERROR,
992  (errcode(ERRCODE_PROTOCOL_VIOLATION),
993  errmsg("malformed SCRAM message"),
994  errdetail("Comma expected, but found character \"%s\".",
995  sanitize_char(*p))));
996  p++;
997  break;
998  case 'y':
999 
1000  /*
1001  * The client supports channel binding and thinks that the server
1002  * does not. In this case, the server must fail authentication if
1003  * it supports channel binding.
1004  */
1005  if (state->channel_binding_in_use)
1006  ereport(ERROR,
1007  (errcode(ERRCODE_PROTOCOL_VIOLATION),
1008  errmsg("malformed SCRAM message"),
1009  errdetail("The client selected SCRAM-SHA-256-PLUS, but the SCRAM message does not include channel binding data.")));
1010 
1011 #ifdef USE_SSL
1012  if (state->port->ssl_in_use)
1013  ereport(ERROR,
1014  (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
1015  errmsg("SCRAM channel binding negotiation error"),
1016  errdetail("The client supports SCRAM channel binding but thinks the server does not. "
1017  "However, this server does support channel binding.")));
1018 #endif
1019  p++;
1020  if (*p != ',')
1021  ereport(ERROR,
1022  (errcode(ERRCODE_PROTOCOL_VIOLATION),
1023  errmsg("malformed SCRAM message"),
1024  errdetail("Comma expected, but found character \"%s\".",
1025  sanitize_char(*p))));
1026  p++;
1027  break;
1028  case 'p':
1029 
1030  /*
1031  * The client requires channel binding. Channel binding type
1032  * follows, e.g., "p=tls-server-end-point".
1033  */
1034  if (!state->channel_binding_in_use)
1035  ereport(ERROR,
1036  (errcode(ERRCODE_PROTOCOL_VIOLATION),
1037  errmsg("malformed SCRAM message"),
1038  errdetail("The client selected SCRAM-SHA-256 without channel binding, but the SCRAM message includes channel binding data.")));
1039 
1040  channel_binding_type = read_attr_value(&p, 'p');
1041 
1042  /*
1043  * The only channel binding type we support is
1044  * tls-server-end-point.
1045  */
1046  if (strcmp(channel_binding_type, "tls-server-end-point") != 0)
1047  ereport(ERROR,
1048  (errcode(ERRCODE_PROTOCOL_VIOLATION),
1049  errmsg("unsupported SCRAM channel-binding type \"%s\"",
1050  sanitize_str(channel_binding_type))));
1051  break;
1052  default:
1053  ereport(ERROR,
1054  (errcode(ERRCODE_PROTOCOL_VIOLATION),
1055  errmsg("malformed SCRAM message"),
1056  errdetail("Unexpected channel-binding flag \"%s\".",
1057  sanitize_char(*p))));
1058  }
1059 
1060  /*
1061  * Forbid optional authzid (authorization identity). We don't support it.
1062  */
1063  if (*p == 'a')
1064  ereport(ERROR,
1065  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1066  errmsg("client uses authorization identity, but it is not supported")));
1067  if (*p != ',')
1068  ereport(ERROR,
1069  (errcode(ERRCODE_PROTOCOL_VIOLATION),
1070  errmsg("malformed SCRAM message"),
1071  errdetail("Unexpected attribute \"%s\" in client-first-message.",
1072  sanitize_char(*p))));
1073  p++;
1074 
1075  state->client_first_message_bare = pstrdup(p);
1076 
1077  /*
1078  * Any mandatory extensions would go here. We don't support any.
1079  *
1080  * RFC 5802 specifies error code "e=extensions-not-supported" for this,
1081  * but it can only be sent in the server-final message. We prefer to fail
1082  * immediately (which the RFC also allows).
1083  */
1084  if (*p == 'm')
1085  ereport(ERROR,
1086  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1087  errmsg("client requires an unsupported SCRAM extension")));
1088 
1089  /*
1090  * Read username. Note: this is ignored. We use the username from the
1091  * startup message instead, still it is kept around if provided as it
1092  * proves to be useful for debugging purposes.
1093  */
1094  state->client_username = read_attr_value(&p, 'n');
1095 
1096  /* read nonce and check that it is made of only printable characters */
1097  state->client_nonce = read_attr_value(&p, 'r');
1098  if (!is_scram_printable(state->client_nonce))
1099  ereport(ERROR,
1100  (errcode(ERRCODE_PROTOCOL_VIOLATION),
1101  errmsg("non-printable characters in SCRAM nonce")));
1102 
1103  /*
1104  * There can be any number of optional extensions after this. We don't
1105  * support any extensions, so ignore them.
1106  */
1107  while (*p != '\0')
1108  read_any_attr(&p, NULL);
1109 
1110  /* success! */
1111 }
static char * sanitize_str(const char *s)
Definition: auth-scram.c:818
static bool is_scram_printable(char *p)
Definition: auth-scram.c:770

References ereport, errcode(), errdetail(), errmsg(), ERROR, input, is_scram_printable(), pstrdup(), read_any_attr(), read_attr_value(), sanitize_char(), and sanitize_str().

Referenced by scram_exchange().

◆ sanitize_char()

static char * sanitize_char ( char  c)
static

Definition at line 798 of file auth-scram.c.

799 {
800  static char buf[5];
801 
802  if (c >= 0x21 && c <= 0x7E)
803  snprintf(buf, sizeof(buf), "'%c'", c);
804  else
805  snprintf(buf, sizeof(buf), "0x%02x", (unsigned char) c);
806  return buf;
807 }
static char * buf
Definition: pg_test_fsync.c:72
char * c

References buf, and snprintf.

Referenced by read_any_attr(), read_attr_value(), and read_client_first_message().

◆ sanitize_str()

static char * sanitize_str ( const char *  s)
static

Definition at line 818 of file auth-scram.c.

819 {
820  static char buf[30 + 1];
821  int i;
822 
823  for (i = 0; i < sizeof(buf) - 1; i++)
824  {
825  char c = s[i];
826 
827  if (c == '\0')
828  break;
829 
830  if (c >= 0x21 && c <= 0x7E)
831  buf[i] = c;
832  else
833  buf[i] = '?';
834  }
835  buf[i] = '\0';
836  return buf;
837 }
int i
Definition: isn.c:72

References buf, and i.

Referenced by read_client_first_message().

◆ scram_exchange()

static int scram_exchange ( void *  opaq,
const char *  input,
int  inputlen,
char **  output,
int *  outputlen,
const char **  logdetail 
)
static

Definition at line 350 of file auth-scram.c.

352 {
353  scram_state *state = (scram_state *) opaq;
354  int result;
355 
356  *output = NULL;
357 
358  /*
359  * If the client didn't include an "Initial Client Response" in the
360  * SASLInitialResponse message, send an empty challenge, to which the
361  * client will respond with the same data that usually comes in the
362  * Initial Client Response.
363  */
364  if (input == NULL)
365  {
366  Assert(state->state == SCRAM_AUTH_INIT);
367 
368  *output = pstrdup("");
369  *outputlen = 0;
371  }
372 
373  /*
374  * Check that the input length agrees with the string length of the input.
375  * We can ignore inputlen after this.
376  */
377  if (inputlen == 0)
378  ereport(ERROR,
379  (errcode(ERRCODE_PROTOCOL_VIOLATION),
380  errmsg("malformed SCRAM message"),
381  errdetail("The message is empty.")));
382  if (inputlen != strlen(input))
383  ereport(ERROR,
384  (errcode(ERRCODE_PROTOCOL_VIOLATION),
385  errmsg("malformed SCRAM message"),
386  errdetail("Message length does not match input length.")));
387 
388  switch (state->state)
389  {
390  case SCRAM_AUTH_INIT:
391 
392  /*
393  * Initialization phase. Receive the first message from client
394  * and be sure that it parsed correctly. Then send the challenge
395  * to the client.
396  */
398 
399  /* prepare message to send challenge */
401 
402  state->state = SCRAM_AUTH_SALT_SENT;
403  result = PG_SASL_EXCHANGE_CONTINUE;
404  break;
405 
407 
408  /*
409  * Final phase for the server. Receive the response to the
410  * challenge previously sent, verify, and let the client know that
411  * everything went well (or not).
412  */
414 
416  ereport(ERROR,
417  (errcode(ERRCODE_PROTOCOL_VIOLATION),
418  errmsg("invalid SCRAM response"),
419  errdetail("Nonce does not match.")));
420 
421  /*
422  * Now check the final nonce and the client proof.
423  *
424  * If we performed a "mock" authentication that we knew would fail
425  * from the get go, this is where we fail.
426  *
427  * The SCRAM specification includes an error code,
428  * "invalid-proof", for authentication failure, but it also allows
429  * erroring out in an application-specific way. We choose to do
430  * the latter, so that the error message for invalid password is
431  * the same for all authentication methods. The caller will call
432  * ereport(), when we return PG_SASL_EXCHANGE_FAILURE with no
433  * output.
434  *
435  * NB: the order of these checks is intentional. We calculate the
436  * client proof even in a mock authentication, even though it's
437  * bound to fail, to thwart timing attacks to determine if a role
438  * with the given name exists or not.
439  */
440  if (!verify_client_proof(state) || state->doomed)
441  {
442  result = PG_SASL_EXCHANGE_FAILURE;
443  break;
444  }
445 
446  /* Build final message for client */
448 
449  /* Success! */
450  result = PG_SASL_EXCHANGE_SUCCESS;
451  state->state = SCRAM_AUTH_FINISHED;
452  break;
453 
454  default:
455  elog(ERROR, "invalid SCRAM exchange state");
456  result = PG_SASL_EXCHANGE_FAILURE;
457  }
458 
459  if (result == PG_SASL_EXCHANGE_FAILURE && state->logdetail && logdetail)
460  *logdetail = state->logdetail;
461 
462  if (*output)
463  *outputlen = strlen(*output);
464 
465  return result;
466 }
static char * build_server_first_message(scram_state *state)
Definition: auth-scram.c:1194
static void read_client_first_message(scram_state *state, const char *input)
Definition: auth-scram.c:904
static bool verify_client_proof(scram_state *state)
Definition: auth-scram.c:1140
static bool verify_final_nonce(scram_state *state)
Definition: auth-scram.c:1118
static void read_client_final_message(scram_state *state, const char *input)
Definition: auth-scram.c:1258
static char * build_server_final_message(scram_state *state)
Definition: auth-scram.c:1404
FILE * output
#define PG_SASL_EXCHANGE_FAILURE
Definition: sasl.h:27
#define PG_SASL_EXCHANGE_CONTINUE
Definition: sasl.h:25
#define PG_SASL_EXCHANGE_SUCCESS
Definition: sasl.h:26

References Assert, build_server_final_message(), build_server_first_message(), elog, ereport, errcode(), errdetail(), errmsg(), ERROR, input, output, PG_SASL_EXCHANGE_CONTINUE, PG_SASL_EXCHANGE_FAILURE, PG_SASL_EXCHANGE_SUCCESS, pstrdup(), read_client_final_message(), read_client_first_message(), SCRAM_AUTH_FINISHED, SCRAM_AUTH_INIT, SCRAM_AUTH_SALT_SENT, verify_client_proof(), and verify_final_nonce().

◆ scram_get_mechanisms()

static void scram_get_mechanisms ( Port port,
StringInfo  buf 
)
static

Definition at line 204 of file auth-scram.c.

205 {
206  /*
207  * Advertise the mechanisms in decreasing order of importance. So the
208  * channel-binding variants go first, if they are supported. Channel
209  * binding is only supported with SSL.
210  */
211 #ifdef USE_SSL
212  if (port->ssl_in_use)
213  {
215  appendStringInfoChar(buf, '\0');
216  }
217 #endif
219  appendStringInfoChar(buf, '\0');
220 }
static int port
Definition: pg_regress.c:115
#define SCRAM_SHA_256_PLUS_NAME
Definition: scram-common.h:21
#define SCRAM_SHA_256_NAME
Definition: scram-common.h:20
void appendStringInfoString(StringInfo str, const char *s)
Definition: stringinfo.c:179
void appendStringInfoChar(StringInfo str, char ch)
Definition: stringinfo.c:191

References appendStringInfoChar(), appendStringInfoString(), buf, port, SCRAM_SHA_256_NAME, and SCRAM_SHA_256_PLUS_NAME.

◆ scram_init()

static void * scram_init ( Port port,
const char *  selected_mech,
const char *  shadow_pass 
)
static

Definition at line 238 of file auth-scram.c.

239 {
241  bool got_secret;
242 
243  state = (scram_state *) palloc0(sizeof(scram_state));
244  state->port = port;
245  state->state = SCRAM_AUTH_INIT;
246 
247  /*
248  * Parse the selected mechanism.
249  *
250  * Note that if we don't support channel binding, or if we're not using
251  * SSL at all, we would not have advertised the PLUS variant in the first
252  * place. If the client nevertheless tries to select it, it's a protocol
253  * violation like selecting any other SASL mechanism we don't support.
254  */
255 #ifdef USE_SSL
256  if (strcmp(selected_mech, SCRAM_SHA_256_PLUS_NAME) == 0 && port->ssl_in_use)
257  state->channel_binding_in_use = true;
258  else
259 #endif
260  if (strcmp(selected_mech, SCRAM_SHA_256_NAME) == 0)
261  state->channel_binding_in_use = false;
262  else
263  ereport(ERROR,
264  (errcode(ERRCODE_PROTOCOL_VIOLATION),
265  errmsg("client selected an invalid SASL authentication mechanism")));
266 
267  /*
268  * Parse the stored secret.
269  */
270  if (shadow_pass)
271  {
272  int password_type = get_password_type(shadow_pass);
273 
274  if (password_type == PASSWORD_TYPE_SCRAM_SHA_256)
275  {
276  if (parse_scram_secret(shadow_pass, &state->iterations,
277  &state->hash_type, &state->key_length,
278  &state->salt,
279  state->StoredKey,
280  state->ServerKey))
281  got_secret = true;
282  else
283  {
284  /*
285  * The password looked like a SCRAM secret, but could not be
286  * parsed.
287  */
288  ereport(LOG,
289  (errmsg("invalid SCRAM secret for user \"%s\"",
290  state->port->user_name)));
291  got_secret = false;
292  }
293  }
294  else
295  {
296  /*
297  * The user doesn't have SCRAM secret. (You cannot do SCRAM
298  * authentication with an MD5 hash.)
299  */
300  state->logdetail = psprintf(_("User \"%s\" does not have a valid SCRAM secret."),
301  state->port->user_name);
302  got_secret = false;
303  }
304  }
305  else
306  {
307  /*
308  * The caller requested us to perform a dummy authentication. This is
309  * considered normal, since the caller requested it, so don't set log
310  * detail.
311  */
312  got_secret = false;
313  }
314 
315  /*
316  * If the user did not have a valid SCRAM secret, we still go through the
317  * motions with a mock one, and fail as if the client supplied an
318  * incorrect password. This is to avoid revealing information to an
319  * attacker.
320  */
321  if (!got_secret)
322  {
323  mock_scram_secret(state->port->user_name, &state->hash_type,
324  &state->iterations, &state->key_length,
325  &state->salt,
326  state->StoredKey, state->ServerKey);
327  state->doomed = true;
328  }
329 
330  return state;
331 }
bool parse_scram_secret(const char *secret, int *iterations, pg_cryptohash_type *hash_type, int *key_length, char **salt, uint8 *stored_key, uint8 *server_key)
Definition: auth-scram.c:591
static void mock_scram_secret(const char *username, pg_cryptohash_type *hash_type, int *iterations, int *key_length, char **salt, uint8 *stored_key, uint8 *server_key)
Definition: auth-scram.c:688
PasswordType get_password_type(const char *shadow_pass)
Definition: crypt.c:90
@ PASSWORD_TYPE_SCRAM_SHA_256
Definition: crypt.h:44
#define _(x)
Definition: elog.c:90
#define LOG
Definition: elog.h:31
if(TABLE==NULL||TABLE_index==NULL)
Definition: isn.c:76
void * palloc0(Size size)
Definition: mcxt.c:1347

References _, ereport, errcode(), errmsg(), ERROR, get_password_type(), if(), LOG, mock_scram_secret(), palloc0(), parse_scram_secret(), PASSWORD_TYPE_SCRAM_SHA_256, port, psprintf(), SCRAM_AUTH_INIT, SCRAM_SHA_256_NAME, and SCRAM_SHA_256_PLUS_NAME.

◆ scram_mock_salt()

static char * scram_mock_salt ( const char *  username,
pg_cryptohash_type  hash_type,
int  key_length 
)
static

Definition at line 1463 of file auth-scram.c.

1465 {
1466  pg_cryptohash_ctx *ctx;
1467  static uint8 sha_digest[SCRAM_MAX_KEY_LEN];
1468  char *mock_auth_nonce = GetMockAuthenticationNonce();
1469 
1470  /*
1471  * Generate salt using a SHA256 hash of the username and the cluster's
1472  * mock authentication nonce. (This works as long as the salt length is
1473  * not larger than the SHA256 digest length. If the salt is smaller, the
1474  * caller will just ignore the extra data.)
1475  */
1477  "salt length greater than SHA256 digest length");
1478 
1479  /*
1480  * This may be worth refreshing if support for more hash methods is\
1481  * added.
1482  */
1483  Assert(hash_type == PG_SHA256);
1484 
1485  ctx = pg_cryptohash_create(hash_type);
1486  if (pg_cryptohash_init(ctx) < 0 ||
1487  pg_cryptohash_update(ctx, (uint8 *) username, strlen(username)) < 0 ||
1488  pg_cryptohash_update(ctx, (uint8 *) mock_auth_nonce, MOCK_AUTH_NONCE_LEN) < 0 ||
1489  pg_cryptohash_final(ctx, sha_digest, key_length) < 0)
1490  {
1491  pg_cryptohash_free(ctx);
1492  return NULL;
1493  }
1494  pg_cryptohash_free(ctx);
1495 
1496  return (char *) sha_digest;
1497 }
#define StaticAssertDecl(condition, errmessage)
Definition: c.h:915
int pg_cryptohash_update(pg_cryptohash_ctx *ctx, const uint8 *data, size_t len)
Definition: cryptohash.c:136
int pg_cryptohash_init(pg_cryptohash_ctx *ctx)
Definition: cryptohash.c:100
void pg_cryptohash_free(pg_cryptohash_ctx *ctx)
Definition: cryptohash.c:238
pg_cryptohash_ctx * pg_cryptohash_create(pg_cryptohash_type type)
Definition: cryptohash.c:74
int pg_cryptohash_final(pg_cryptohash_ctx *ctx, uint8 *dest, size_t len)
Definition: cryptohash.c:172
#define MOCK_AUTH_NONCE_LEN
Definition: pg_control.h:28
#define PG_SHA256_DIGEST_LENGTH
Definition: sha2.h:23
char * GetMockAuthenticationNonce(void)
Definition: xlog.c:4578

References Assert, GetMockAuthenticationNonce(), MOCK_AUTH_NONCE_LEN, pg_cryptohash_create(), pg_cryptohash_final(), pg_cryptohash_free(), pg_cryptohash_init(), pg_cryptohash_update(), PG_SHA256, PG_SHA256_DIGEST_LENGTH, SCRAM_DEFAULT_SALT_LEN, SCRAM_MAX_KEY_LEN, StaticAssertDecl, and username.

Referenced by mock_scram_secret().

◆ scram_verify_plain_password()

bool scram_verify_plain_password ( const char *  username,
const char *  password,
const char *  secret 
)

Definition at line 514 of file auth-scram.c.

516 {
517  char *encoded_salt;
518  char *salt;
519  int saltlen;
520  int iterations;
521  int key_length = 0;
522  pg_cryptohash_type hash_type;
523  uint8 salted_password[SCRAM_MAX_KEY_LEN];
524  uint8 stored_key[SCRAM_MAX_KEY_LEN];
525  uint8 server_key[SCRAM_MAX_KEY_LEN];
526  uint8 computed_key[SCRAM_MAX_KEY_LEN];
527  char *prep_password;
528  pg_saslprep_rc rc;
529  const char *errstr = NULL;
530 
531  if (!parse_scram_secret(secret, &iterations, &hash_type, &key_length,
532  &encoded_salt, stored_key, server_key))
533  {
534  /*
535  * The password looked like a SCRAM secret, but could not be parsed.
536  */
537  ereport(LOG,
538  (errmsg("invalid SCRAM secret for user \"%s\"", username)));
539  return false;
540  }
541 
542  saltlen = pg_b64_dec_len(strlen(encoded_salt));
543  salt = palloc(saltlen);
544  saltlen = pg_b64_decode(encoded_salt, strlen(encoded_salt), salt,
545  saltlen);
546  if (saltlen < 0)
547  {
548  ereport(LOG,
549  (errmsg("invalid SCRAM secret for user \"%s\"", username)));
550  return false;
551  }
552 
553  /* Normalize the password */
554  rc = pg_saslprep(password, &prep_password);
555  if (rc == SASLPREP_SUCCESS)
556  password = prep_password;
557 
558  /* Compute Server Key based on the user-supplied plaintext password */
559  if (scram_SaltedPassword(password, hash_type, key_length,
560  salt, saltlen, iterations,
561  salted_password, &errstr) < 0 ||
562  scram_ServerKey(salted_password, hash_type, key_length,
563  computed_key, &errstr) < 0)
564  {
565  elog(ERROR, "could not compute server key: %s", errstr);
566  }
567 
568  if (prep_password)
569  pfree(prep_password);
570 
571  /*
572  * Compare the secret's Server Key with the one computed from the
573  * user-supplied password.
574  */
575  return memcmp(computed_key, server_key, key_length) == 0;
576 }
pg_cryptohash_type
Definition: cryptohash.h:20
int scram_ServerKey(const uint8 *salted_password, pg_cryptohash_type hash_type, int key_length, uint8 *result, const char **errstr)
Definition: scram-common.c:172
int scram_SaltedPassword(const char *password, pg_cryptohash_type hash_type, int key_length, const char *salt, int saltlen, int iterations, uint8 *result, const char **errstr)
Definition: scram-common.c:38

References elog, ereport, errmsg(), ERROR, iterations, LOG, palloc(), parse_scram_secret(), password, pfree(), pg_b64_dec_len(), pg_b64_decode(), pg_saslprep(), SASLPREP_SUCCESS, SCRAM_MAX_KEY_LEN, scram_SaltedPassword(), scram_ServerKey(), and username.

Referenced by plain_crypt_verify().

◆ verify_client_proof()

static bool verify_client_proof ( scram_state state)
static

Definition at line 1140 of file auth-scram.c.

1141 {
1142  uint8 ClientSignature[SCRAM_MAX_KEY_LEN];
1143  uint8 ClientKey[SCRAM_MAX_KEY_LEN];
1144  uint8 client_StoredKey[SCRAM_MAX_KEY_LEN];
1145  pg_hmac_ctx *ctx = pg_hmac_create(state->hash_type);
1146  int i;
1147  const char *errstr = NULL;
1148 
1149  /*
1150  * Calculate ClientSignature. Note that we don't log directly a failure
1151  * here even when processing the calculations as this could involve a mock
1152  * authentication.
1153  */
1154  if (pg_hmac_init(ctx, state->StoredKey, state->key_length) < 0 ||
1155  pg_hmac_update(ctx,
1156  (uint8 *) state->client_first_message_bare,
1157  strlen(state->client_first_message_bare)) < 0 ||
1158  pg_hmac_update(ctx, (uint8 *) ",", 1) < 0 ||
1159  pg_hmac_update(ctx,
1160  (uint8 *) state->server_first_message,
1161  strlen(state->server_first_message)) < 0 ||
1162  pg_hmac_update(ctx, (uint8 *) ",", 1) < 0 ||
1163  pg_hmac_update(ctx,
1164  (uint8 *) state->client_final_message_without_proof,
1165  strlen(state->client_final_message_without_proof)) < 0 ||
1166  pg_hmac_final(ctx, ClientSignature, state->key_length) < 0)
1167  {
1168  elog(ERROR, "could not calculate client signature: %s",
1169  pg_hmac_error(ctx));
1170  }
1171 
1172  pg_hmac_free(ctx);
1173 
1174  /* Extract the ClientKey that the client calculated from the proof */
1175  for (i = 0; i < state->key_length; i++)
1176  ClientKey[i] = state->ClientProof[i] ^ ClientSignature[i];
1177 
1178  /* Hash it one more time, and compare with StoredKey */
1179  if (scram_H(ClientKey, state->hash_type, state->key_length,
1180  client_StoredKey, &errstr) < 0)
1181  elog(ERROR, "could not hash stored key: %s", errstr);
1182 
1183  if (memcmp(client_StoredKey, state->StoredKey, state->key_length) != 0)
1184  return false;
1185 
1186  return true;
1187 }
int scram_H(const uint8 *input, pg_cryptohash_type hash_type, int key_length, uint8 *result, const char **errstr)
Definition: scram-common.c:112

References elog, ERROR, i, if(), pg_hmac_create(), pg_hmac_error(), pg_hmac_final(), pg_hmac_free(), pg_hmac_init(), pg_hmac_update(), scram_H(), and SCRAM_MAX_KEY_LEN.

Referenced by scram_exchange().

◆ verify_final_nonce()

static bool verify_final_nonce ( scram_state state)
static

Definition at line 1118 of file auth-scram.c.

1119 {
1120  int client_nonce_len = strlen(state->client_nonce);
1121  int server_nonce_len = strlen(state->server_nonce);
1122  int final_nonce_len = strlen(state->client_final_nonce);
1123 
1124  if (final_nonce_len != client_nonce_len + server_nonce_len)
1125  return false;
1126  if (memcmp(state->client_final_nonce, state->client_nonce, client_nonce_len) != 0)
1127  return false;
1128  if (memcmp(state->client_final_nonce + client_nonce_len, state->server_nonce, server_nonce_len) != 0)
1129  return false;
1130 
1131  return true;
1132 }

Referenced by scram_exchange().

Variable Documentation

◆ pg_be_scram_mech

const pg_be_sasl_mech pg_be_scram_mech
Initial value:
= {
}
static void * scram_init(Port *port, const char *selected_mech, const char *shadow_pass)
Definition: auth-scram.c:238
static int scram_exchange(void *opaq, const char *input, int inputlen, char **output, int *outputlen, const char **logdetail)
Definition: auth-scram.c:350
static void scram_get_mechanisms(Port *port, StringInfo buf)
Definition: auth-scram.c:204
#define PG_MAX_SASL_MESSAGE_LENGTH
Definition: sasl.h:35

Definition at line 113 of file auth-scram.c.

Referenced by CheckPWChallengeAuth().

◆ scram_sha_256_iterations

int scram_sha_256_iterations = SCRAM_SHA_256_DEFAULT_ITERATIONS

Definition at line 194 of file auth-scram.c.

Referenced by pg_be_scram_build_secret().