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crypt.c
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1 /*-------------------------------------------------------------------------
2  *
3  * crypt.c
4  * Functions for dealing with encrypted passwords stored in
5  * pg_authid.rolpassword.
6  *
7  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
8  * Portions Copyright (c) 1994, Regents of the University of California
9  *
10  * src/backend/libpq/crypt.c
11  *
12  *-------------------------------------------------------------------------
13  */
14 #include "postgres.h"
15 
16 #include <unistd.h>
17 
18 #include "catalog/pg_authid.h"
19 #include "common/md5.h"
20 #include "common/scram-common.h"
21 #include "libpq/crypt.h"
22 #include "libpq/scram.h"
23 #include "miscadmin.h"
24 #include "utils/builtins.h"
25 #include "utils/syscache.h"
26 #include "utils/timestamp.h"
27 
28 
29 /*
30  * Fetch stored password for a user, for authentication.
31  *
32  * On error, returns NULL, and stores a palloc'd string describing the reason,
33  * for the postmaster log, in *logdetail. The error reason should *not* be
34  * sent to the client, to avoid giving away user information!
35  */
36 char *
37 get_role_password(const char *role, char **logdetail)
38 {
39  TimestampTz vuntil = 0;
40  HeapTuple roleTup;
41  Datum datum;
42  bool isnull;
43  char *shadow_pass;
44 
45  /* Get role info from pg_authid */
46  roleTup = SearchSysCache1(AUTHNAME, PointerGetDatum(role));
47  if (!HeapTupleIsValid(roleTup))
48  {
49  *logdetail = psprintf(_("Role \"%s\" does not exist."),
50  role);
51  return NULL; /* no such user */
52  }
53 
54  datum = SysCacheGetAttr(AUTHNAME, roleTup,
55  Anum_pg_authid_rolpassword, &isnull);
56  if (isnull)
57  {
58  ReleaseSysCache(roleTup);
59  *logdetail = psprintf(_("User \"%s\" has no password assigned."),
60  role);
61  return NULL; /* user has no password */
62  }
63  shadow_pass = TextDatumGetCString(datum);
64 
65  datum = SysCacheGetAttr(AUTHNAME, roleTup,
66  Anum_pg_authid_rolvaliduntil, &isnull);
67  if (!isnull)
68  vuntil = DatumGetTimestampTz(datum);
69 
70  ReleaseSysCache(roleTup);
71 
72  /*
73  * Password OK, but check to be sure we are not past rolvaliduntil
74  */
75  if (!isnull && vuntil < GetCurrentTimestamp())
76  {
77  *logdetail = psprintf(_("User \"%s\" has an expired password."),
78  role);
79  return NULL;
80  }
81 
82  return shadow_pass;
83 }
84 
85 /*
86  * What kind of a password type is 'shadow_pass'?
87  */
89 get_password_type(const char *shadow_pass)
90 {
91  char *encoded_salt;
92  int iterations;
93  uint8 stored_key[SCRAM_KEY_LEN];
94  uint8 server_key[SCRAM_KEY_LEN];
95 
96  if (strncmp(shadow_pass, "md5", 3) == 0 &&
97  strlen(shadow_pass) == MD5_PASSWD_LEN &&
98  strspn(shadow_pass + 3, MD5_PASSWD_CHARSET) == MD5_PASSWD_LEN - 3)
99  return PASSWORD_TYPE_MD5;
100  if (parse_scram_secret(shadow_pass, &iterations, &encoded_salt,
101  stored_key, server_key))
104 }
105 
106 /*
107  * Given a user-supplied password, convert it into a secret of
108  * 'target_type' kind.
109  *
110  * If the password is already in encrypted form, we cannot reverse the
111  * hash, so it is stored as it is regardless of the requested type.
112  */
113 char *
114 encrypt_password(PasswordType target_type, const char *role,
115  const char *password)
116 {
117  PasswordType guessed_type = get_password_type(password);
118  char *encrypted_password;
119 
120  if (guessed_type != PASSWORD_TYPE_PLAINTEXT)
121  {
122  /*
123  * Cannot convert an already-encrypted password from one format to
124  * another, so return it as it is.
125  */
126  return pstrdup(password);
127  }
128 
129  switch (target_type)
130  {
131  case PASSWORD_TYPE_MD5:
132  encrypted_password = palloc(MD5_PASSWD_LEN + 1);
133 
134  if (!pg_md5_encrypt(password, role, strlen(role),
135  encrypted_password))
136  elog(ERROR, "password encryption failed");
137  return encrypted_password;
138 
140  return pg_be_scram_build_secret(password);
141 
143  elog(ERROR, "cannot encrypt password with 'plaintext'");
144  }
145 
146  /*
147  * This shouldn't happen, because the above switch statements should
148  * handle every combination of source and target password types.
149  */
150  elog(ERROR, "cannot encrypt password to requested type");
151  return NULL; /* keep compiler quiet */
152 }
153 
154 /*
155  * Check MD5 authentication response, and return STATUS_OK or STATUS_ERROR.
156  *
157  * 'shadow_pass' is the user's correct password or password hash, as stored
158  * in pg_authid.rolpassword.
159  * 'client_pass' is the response given by the remote user to the MD5 challenge.
160  * 'md5_salt' is the salt used in the MD5 authentication challenge.
161  *
162  * In the error case, optionally store a palloc'd string at *logdetail
163  * that will be sent to the postmaster log (but not the client).
164  */
165 int
166 md5_crypt_verify(const char *role, const char *shadow_pass,
167  const char *client_pass,
168  const char *md5_salt, int md5_salt_len,
169  char **logdetail)
170 {
171  int retval;
172  char crypt_pwd[MD5_PASSWD_LEN + 1];
173 
174  Assert(md5_salt_len > 0);
175 
176  if (get_password_type(shadow_pass) != PASSWORD_TYPE_MD5)
177  {
178  /* incompatible password hash format. */
179  *logdetail = psprintf(_("User \"%s\" has a password that cannot be used with MD5 authentication."),
180  role);
181  return STATUS_ERROR;
182  }
183 
184  /*
185  * Compute the correct answer for the MD5 challenge.
186  *
187  * We do not bother setting logdetail for any pg_md5_encrypt failure
188  * below: the only possible error is out-of-memory, which is unlikely, and
189  * if it did happen adding a psprintf call would only make things worse.
190  */
191  /* stored password already encrypted, only do salt */
192  if (!pg_md5_encrypt(shadow_pass + strlen("md5"),
193  md5_salt, md5_salt_len,
194  crypt_pwd))
195  {
196  return STATUS_ERROR;
197  }
198 
199  if (strcmp(client_pass, crypt_pwd) == 0)
200  retval = STATUS_OK;
201  else
202  {
203  *logdetail = psprintf(_("Password does not match for user \"%s\"."),
204  role);
205  retval = STATUS_ERROR;
206  }
207 
208  return retval;
209 }
210 
211 /*
212  * Check given password for given user, and return STATUS_OK or STATUS_ERROR.
213  *
214  * 'shadow_pass' is the user's correct password hash, as stored in
215  * pg_authid.rolpassword.
216  * 'client_pass' is the password given by the remote user.
217  *
218  * In the error case, optionally store a palloc'd string at *logdetail
219  * that will be sent to the postmaster log (but not the client).
220  */
221 int
222 plain_crypt_verify(const char *role, const char *shadow_pass,
223  const char *client_pass,
224  char **logdetail)
225 {
226  char crypt_client_pass[MD5_PASSWD_LEN + 1];
227 
228  /*
229  * Client sent password in plaintext. If we have an MD5 hash stored, hash
230  * the password the client sent, and compare the hashes. Otherwise
231  * compare the plaintext passwords directly.
232  */
233  switch (get_password_type(shadow_pass))
234  {
237  client_pass,
238  shadow_pass))
239  {
240  return STATUS_OK;
241  }
242  else
243  {
244  *logdetail = psprintf(_("Password does not match for user \"%s\"."),
245  role);
246  return STATUS_ERROR;
247  }
248  break;
249 
250  case PASSWORD_TYPE_MD5:
251  if (!pg_md5_encrypt(client_pass,
252  role,
253  strlen(role),
254  crypt_client_pass))
255  {
256  /*
257  * We do not bother setting logdetail for pg_md5_encrypt
258  * failure: the only possible error is out-of-memory, which is
259  * unlikely, and if it did happen adding a psprintf call would
260  * only make things worse.
261  */
262  return STATUS_ERROR;
263  }
264  if (strcmp(crypt_client_pass, shadow_pass) == 0)
265  return STATUS_OK;
266  else
267  {
268  *logdetail = psprintf(_("Password does not match for user \"%s\"."),
269  role);
270  return STATUS_ERROR;
271  }
272  break;
273 
275 
276  /*
277  * We never store passwords in plaintext, so this shouldn't
278  * happen.
279  */
280  break;
281  }
282 
283  /*
284  * This shouldn't happen. Plain "password" authentication is possible
285  * with any kind of stored password hash.
286  */
287  *logdetail = psprintf(_("Password of user \"%s\" is in unrecognized format."),
288  role);
289  return STATUS_ERROR;
290 }
static char password[100]
Definition: streamutil.c:53
TimestampTz GetCurrentTimestamp(void)
Definition: timestamp.c:1583
int64 TimestampTz
Definition: timestamp.h:39
#define PointerGetDatum(X)
Definition: postgres.h:556
char * pstrdup(const char *in)
Definition: mcxt.c:1186
char * psprintf(const char *fmt,...)
Definition: psprintf.c:46
char * encrypt_password(PasswordType target_type, const char *role, const char *password)
Definition: crypt.c:114
unsigned char uint8
Definition: c.h:357
int plain_crypt_verify(const char *role, const char *shadow_pass, const char *client_pass, char **logdetail)
Definition: crypt.c:222
#define STATUS_ERROR
Definition: c.h:1121
char * pg_be_scram_build_secret(const char *password)
Definition: auth-scram.c:451
bool pg_md5_encrypt(const char *passwd, const char *salt, size_t salt_len, char *buf)
Definition: md5.c:323
#define ERROR
Definition: elog.h:43
char * get_role_password(const char *role, char **logdetail)
Definition: crypt.c:37
bool scram_verify_plain_password(const char *username, const char *password, const char *secret)
Definition: auth-scram.c:488
#define DatumGetTimestampTz(X)
Definition: timestamp.h:28
#define STATUS_OK
Definition: c.h:1120
HeapTuple SearchSysCache1(int cacheId, Datum key1)
Definition: syscache.c:1116
#define MD5_PASSWD_CHARSET
Definition: md5.h:19
int md5_crypt_verify(const char *role, const char *shadow_pass, const char *client_pass, const char *md5_salt, int md5_salt_len, char **logdetail)
Definition: crypt.c:166
#define TextDatumGetCString(d)
Definition: builtins.h:84
uintptr_t Datum
Definition: postgres.h:367
void ReleaseSysCache(HeapTuple tuple)
Definition: syscache.c:1164
Datum SysCacheGetAttr(int cacheId, HeapTuple tup, AttrNumber attributeNumber, bool *isNull)
Definition: syscache.c:1377
PasswordType
Definition: crypt.h:27
#define MD5_PASSWD_LEN
Definition: md5.h:20
#define HeapTupleIsValid(tuple)
Definition: htup.h:78
#define Assert(condition)
Definition: c.h:739
bool parse_scram_secret(const char *secret, int *iterations, char **salt, uint8 *stored_key, uint8 *server_key)
Definition: auth-scram.c:556
void * palloc(Size size)
Definition: mcxt.c:949
PasswordType get_password_type(const char *shadow_pass)
Definition: crypt.c:89
#define elog(elevel,...)
Definition: elog.h:228
#define SCRAM_KEY_LEN
Definition: scram-common.h:23
#define _(x)
Definition: elog.c:87