LCOV - code coverage report
Current view: top level - contrib/pgcrypto - crypt-sha.c (source / functions) Hit Total Coverage
Test: PostgreSQL 18devel Lines: 171 206 83.0 %
Date: 2025-04-24 13:15:39 Functions: 1 1 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*
       2             :  * contrib/pgcrypto/crypt-sha.c
       3             :  *
       4             :  * This implements shacrypt password hash functions and follows the
       5             :  * public available reference implementation from
       6             :  *
       7             :  * https://www.akkadia.org/drepper/SHA-crypt.txt
       8             :  *
       9             :  * This code is public domain.
      10             :  *
      11             :  * Please see the inline comments for details about the algorithm.
      12             :  *
      13             :  * Basically the following code implements password hashing with sha256 and
      14             :  * sha512 digest via OpenSSL. Additionally, an extended salt generation (see
      15             :  * crypt-gensalt.c for details) is provided, which generates a salt suitable
      16             :  * for either sha256crypt and sha512crypt password hash generation.
      17             :  *
      18             :  * Official identifiers for suitable password hashes used in salts are
      19             :  * 5 : sha256crypt and
      20             :  * 6 : sha512crypt
      21             :  *
      22             :  * The hashing code below supports and uses salt length up to 16 bytes. Longer
      23             :  * input is possible, but any additional byte of the input is disregarded.
      24             :  * gen_salt(), when called with a sha256crypt or sha512crypt identifier will
      25             :  * always generate a 16 byte long salt string.
      26             :  *
      27             :  * Output is compatible with any sha256crypt and sha512crypt output
      28             :  * generated by e.g. OpenSSL or libc crypt().
      29             :  *
      30             :  * The described algorithm uses default computing rounds of 5000. Currently,
      31             :  * even when no specific rounds specification is used, we always explicitly
      32             :  * print out the rounds option flag with the final hash password string.
      33             :  *
      34             :  * The length of the specific password hash (without magic bytes and salt
      35             :  * string) is:
      36             :  *
      37             :  * sha256crypt: 43 bytes and
      38             :  * sha512crypt: 86 bytes.
      39             :  *
      40             :  * Overall hashed password length is:
      41             :  *
      42             :  * sha256crypt: 80 bytes and
      43             :  * sha512crypt: 123 bytes
      44             :  *
      45             :  */
      46             : #include "postgres.h"
      47             : 
      48             : #include "common/string.h"
      49             : #include "mb/pg_wchar.h"
      50             : #include "miscadmin.h"
      51             : 
      52             : #include "px-crypt.h"
      53             : #include "px.h"
      54             : 
      55             : typedef enum
      56             : {
      57             :     PGCRYPTO_SHA256CRYPT = 0,
      58             :     PGCRYPTO_SHA512CRYPT = 1,
      59             :     PGCRYPTO_SHA_UNKOWN
      60             : } PGCRYPTO_SHA_t;
      61             : 
      62             : static const char _crypt_itoa64[64 + 1] =
      63             : "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
      64             : 
      65             : /*
      66             :  * Modern UNIX password, based on SHA crypt hashes
      67             :  */
      68             : char *
      69          52 : px_crypt_shacrypt(const char *pw, const char *salt, char *passwd, unsigned dstlen)
      70             : {
      71             :     static const char rounds_prefix[] = "rounds=";
      72             :     static const char *magic_bytes[2] = {"$5$", "$6$"};
      73             : 
      74             :     /* Used to create the password hash string */
      75          52 :     StringInfo  out_buf = NULL;
      76             : 
      77          52 :     PGCRYPTO_SHA_t type = PGCRYPTO_SHA_UNKOWN;
      78          52 :     PX_MD      *digestA = NULL;
      79          52 :     PX_MD      *digestB = NULL;
      80             :     int         err;
      81             : 
      82             :     const char *dec_salt_binary;    /* pointer into the real salt string */
      83          52 :     StringInfo  decoded_salt = NULL;    /* decoded salt string */
      84             :     unsigned char sha_buf[PX_SHACRYPT_DIGEST_MAX_LEN];
      85             : 
      86             :     /* temporary buffer for digests */
      87             :     unsigned char sha_buf_tmp[PX_SHACRYPT_DIGEST_MAX_LEN];
      88          52 :     char        rounds_custom = 0;
      89          52 :     char       *p_bytes = NULL;
      90          52 :     char       *s_bytes = NULL;
      91          52 :     char       *cp = NULL;
      92          52 :     const char *fp = NULL;      /* intermediate pointer within salt string */
      93          52 :     const char *ep = NULL;      /* holds pointer to the end of the salt string */
      94          52 :     size_t      buf_size = 0;   /* buffer size for sha256crypt/sha512crypt */
      95             :     unsigned int block;         /* number of bytes processed */
      96          52 :     uint32      rounds = PX_SHACRYPT_ROUNDS_DEFAULT;
      97             :     unsigned int len,
      98          52 :                 salt_len = 0;
      99             : 
     100             :     /* Sanity checks */
     101          52 :     if (!passwd)
     102           0 :         return NULL;
     103             : 
     104          52 :     if (pw == NULL)
     105           0 :         elog(ERROR, "null value for password rejected");
     106             : 
     107          52 :     if (salt == NULL)
     108           0 :         elog(ERROR, "null value for salt rejected");
     109             : 
     110             :     /*
     111             :      * Make sure result buffers are large enough.
     112             :      */
     113          52 :     if (dstlen < PX_SHACRYPT_BUF_LEN)
     114           0 :         elog(ERROR, "insufficient result buffer size to encrypt password");
     115             : 
     116             :     /* Init result buffer */
     117          52 :     out_buf = makeStringInfoExt(PX_SHACRYPT_BUF_LEN);
     118          52 :     decoded_salt = makeStringInfoExt(PX_SHACRYPT_SALT_MAX_LEN);
     119             : 
     120             :     /* Init contents of buffers properly */
     121          52 :     memset(&sha_buf, '\0', sizeof(sha_buf));
     122          52 :     memset(&sha_buf_tmp, '\0', sizeof(sha_buf_tmp));
     123             : 
     124             :     /*
     125             :      * Decode the salt string. We need to know how many rounds and which
     126             :      * digest we have to use to hash the password.
     127             :      */
     128          52 :     len = strlen(pw);
     129          52 :     dec_salt_binary = salt;
     130             : 
     131             :     /*
     132             :      * Analyze and prepare the salt string
     133             :      *
     134             :      * The magic string should be specified in the first three bytes of the
     135             :      * salt string.  Do some sanity checks first.
     136             :      */
     137          52 :     if (strlen(dec_salt_binary) < 3)
     138           0 :         ereport(ERROR,
     139             :                 errcode(ERRCODE_INVALID_PARAMETER_VALUE),
     140             :                 errmsg("invalid salt"));
     141             : 
     142             :     /*
     143             :      * Check format of magic bytes. These should define either 5=sha256crypt
     144             :      * or 6=sha512crypt in the second byte, enclosed by ascii dollar signs.
     145             :      */
     146          52 :     if ((dec_salt_binary[0] != '$') || (dec_salt_binary[2] != '$'))
     147           0 :         ereport(ERROR,
     148             :                 errcode(ERRCODE_INVALID_PARAMETER_VALUE),
     149             :                 errmsg("invalid format of salt"),
     150             :                 errhint("magic byte format for shacrypt is either \"$5$\" or \"$6$\""));
     151             : 
     152             :     /*
     153             :      * Check magic byte for supported shacrypt digest.
     154             :      *
     155             :      * We're just interested in the very first 3 bytes of the salt string,
     156             :      * since this defines the digest length to use.
     157             :      */
     158          52 :     if (strncmp(dec_salt_binary, magic_bytes[0], strlen(magic_bytes[0])) == 0)
     159             :     {
     160          26 :         type = PGCRYPTO_SHA256CRYPT;
     161          26 :         dec_salt_binary += strlen(magic_bytes[0]);
     162             :     }
     163          26 :     else if (strncmp(dec_salt_binary, magic_bytes[1], strlen(magic_bytes[1])) == 0)
     164             :     {
     165          26 :         type = PGCRYPTO_SHA512CRYPT;
     166          26 :         dec_salt_binary += strlen(magic_bytes[1]);
     167             :     }
     168             : 
     169             :     /*
     170             :      * dec_salt_binary pointer is positioned after the magic bytes now
     171             :      *
     172             :      * We extract any options in the following code branch. The only optional
     173             :      * setting we need to take care of is the "rounds" option. Note that the
     174             :      * salt generator already checked for invalid settings before, but we need
     175             :      * to do it here again to protect against injection of wrong values when
     176             :      * called without the generator.
     177             :      *
     178             :      * If there is any garbage added after the magic byte and the options/salt
     179             :      * string, we don't treat this special: This is just absorbed as part of
     180             :      * the salt with up to PX_SHACRYPT_SALT_LEN_MAX.
     181             :      *
     182             :      * Unknown magic byte is handled further below.
     183             :      */
     184          52 :     if (strncmp(dec_salt_binary,
     185             :                 rounds_prefix, sizeof(rounds_prefix) - 1) == 0)
     186             :     {
     187          40 :         const char *num = dec_salt_binary + sizeof(rounds_prefix) - 1;
     188             :         char       *endp;
     189          40 :         int         srounds = strtoint(num, &endp, 10);
     190             : 
     191          40 :         if (*endp != '$')
     192           0 :             ereport(ERROR,
     193             :                     errcode(ERRCODE_SYNTAX_ERROR),
     194             :                     errmsg("could not parse salt options"));
     195             : 
     196          40 :         dec_salt_binary = endp + 1;
     197             : 
     198             :         /*
     199             :          * We violate supported lower or upper bound of rounds, but in this
     200             :          * case we change this value to the supported lower or upper value. We
     201             :          * don't do this silently and print a NOTICE in such a case.
     202             :          *
     203             :          * Note that a salt string generated with gen_salt() would never
     204             :          * generated such a salt string, since it would error out.
     205             :          *
     206             :          * But Drepper's upstream reference implementation supports this when
     207             :          * passing the salt string directly, so we maintain compatibility.
     208             :          */
     209          40 :         if (srounds > PX_SHACRYPT_ROUNDS_MAX)
     210             :         {
     211           0 :             ereport(NOTICE,
     212             :                     errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
     213             :                     errmsg("rounds=%d exceeds maximum supported value (%d), using %d instead",
     214             :                            srounds, PX_SHACRYPT_ROUNDS_MAX,
     215             :                            PX_SHACRYPT_ROUNDS_MAX));
     216           0 :             srounds = PX_SHACRYPT_ROUNDS_MAX;
     217             :         }
     218          40 :         else if (srounds < PX_SHACRYPT_ROUNDS_MIN)
     219             :         {
     220           4 :             ereport(NOTICE,
     221             :                     errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
     222             :                     errmsg("rounds=%d is below supported value (%d), using %d instead",
     223             :                            srounds, PX_SHACRYPT_ROUNDS_MIN,
     224             :                            PX_SHACRYPT_ROUNDS_MIN));
     225           4 :             srounds = PX_SHACRYPT_ROUNDS_MIN;
     226             :         }
     227             : 
     228          40 :         rounds = (uint32) srounds;
     229          40 :         rounds_custom = 1;
     230             :     }
     231             : 
     232             :     /*
     233             :      * Choose the correct digest length and add the magic bytes to the result
     234             :      * buffer. Also handle possible invalid magic byte we've extracted above.
     235             :      */
     236          52 :     switch (type)
     237             :     {
     238          26 :         case PGCRYPTO_SHA256CRYPT:
     239             :             {
     240             :                 /* Two PX_MD objects required */
     241          26 :                 err = px_find_digest("sha256", &digestA);
     242          26 :                 if (err)
     243           0 :                     goto error;
     244             : 
     245          26 :                 err = px_find_digest("sha256", &digestB);
     246          26 :                 if (err)
     247           0 :                     goto error;
     248             : 
     249             :                 /* digest buffer length is 32 for sha256 */
     250          26 :                 buf_size = 32;
     251             : 
     252          26 :                 appendStringInfoString(out_buf, magic_bytes[0]);
     253          26 :                 break;
     254             :             }
     255             : 
     256          26 :         case PGCRYPTO_SHA512CRYPT:
     257             :             {
     258             :                 /* Two PX_MD objects required */
     259          26 :                 err = px_find_digest("sha512", &digestA);
     260          26 :                 if (err)
     261           0 :                     goto error;
     262             : 
     263          26 :                 err = px_find_digest("sha512", &digestB);
     264          26 :                 if (err)
     265           0 :                     goto error;
     266             : 
     267          26 :                 buf_size = PX_SHACRYPT_DIGEST_MAX_LEN;
     268             : 
     269          26 :                 appendStringInfoString(out_buf, magic_bytes[1]);
     270          26 :                 break;
     271             :             }
     272             : 
     273           0 :         case PGCRYPTO_SHA_UNKOWN:
     274           0 :             elog(ERROR, "unknown crypt identifier \"%c\"", salt[1]);
     275             :     }
     276             : 
     277          52 :     if (rounds_custom > 0)
     278          40 :         appendStringInfo(out_buf, "rounds=%u$", rounds);
     279             : 
     280             :     /*
     281             :      * We need the real decoded salt string from salt input, this is every
     282             :      * character before the last '$' in the preamble. Append every compatible
     283             :      * character up to PX_SHACRYPT_SALT_MAX_LEN to the result buffer. Note
     284             :      * that depending on the input, there might be no '$' marker after the
     285             :      * salt, when there is no password hash attached at the end.
     286             :      *
     287             :      * We try hard to recognize mistakes, but since we might get an input
     288             :      * string which might also have the password hash after the salt string
     289             :      * section we give up as soon we reach the end of the input or if there
     290             :      * are any bytes consumed for the salt string until we reach the first '$'
     291             :      * marker thereafter.
     292             :      */
     293          52 :     for (ep = dec_salt_binary;
     294         736 :          *ep && ep < (dec_salt_binary + PX_SHACRYPT_SALT_MAX_LEN);
     295         684 :          ep++)
     296             :     {
     297             :         /*
     298             :          * Filter out any string which shouldn't be here.
     299             :          *
     300             :          * First check for accidentally embedded magic strings here. We don't
     301             :          * support '$' in salt strings anyways and seeing a magic byte trying
     302             :          * to identify shacrypt hashes might indicate that something went
     303             :          * wrong when generating this salt string. Note that we later check
     304             :          * for non-supported literals anyways, but any '$' here confuses us at
     305             :          * this point.
     306             :          */
     307         684 :         fp = strstr(dec_salt_binary, magic_bytes[0]);
     308         684 :         if (fp != NULL)
     309           0 :             elog(ERROR, "bogus magic byte found in salt string");
     310             : 
     311         684 :         fp = strstr(dec_salt_binary, magic_bytes[1]);
     312         684 :         if (fp != NULL)
     313           0 :             elog(ERROR, "bogus magic byte found in salt string");
     314             : 
     315             :         /*
     316             :          * This looks very strict, but we assume the caller did something
     317             :          * wrong when we see a "rounds=" option here.
     318             :          */
     319         684 :         fp = strstr(dec_salt_binary, rounds_prefix);
     320         684 :         if (fp != NULL)
     321           0 :             elog(ERROR, "invalid rounds option specified in salt string");
     322             : 
     323         684 :         if (*ep != '$')
     324             :         {
     325         684 :             if (strchr(_crypt_itoa64, *ep) != NULL)
     326         684 :                 appendStringInfoCharMacro(decoded_salt, *ep);
     327             :             else
     328           0 :                 ereport(ERROR,
     329             :                         errcode(ERRCODE_INVALID_PARAMETER_VALUE),
     330             :                         errmsg("invalid character in salt string: \"%.*s\"",
     331             :                                pg_mblen(ep), ep));
     332             :         }
     333             :         else
     334             :         {
     335             :             /*
     336             :              * We encountered a '$' marker. Check if we already absorbed some
     337             :              * bytes from input. If true, we are optimistic and terminate at
     338             :              * this stage. If not, we try further.
     339             :              *
     340             :              * If we already consumed enough bytes for the salt string,
     341             :              * everything that is after this marker is considered to be part
     342             :              * of an optionally specified password hash and ignored.
     343             :              */
     344           0 :             if (decoded_salt->len > 0)
     345           0 :                 break;
     346             :         }
     347             :     }
     348             : 
     349          52 :     salt_len = decoded_salt->len;
     350          52 :     appendStringInfoString(out_buf, decoded_salt->data);
     351          52 :     elog(DEBUG1, "using salt \"%s\", salt len = %d, rounds = %u",
     352             :          decoded_salt->data, decoded_salt->len, rounds);
     353             : 
     354             :     /*
     355             :      * Sanity check: at this point the salt string buffer must not exceed
     356             :      * expected size.
     357             :      */
     358          52 :     if (out_buf->len > (3 + 17 * rounds_custom + salt_len))
     359           0 :         elog(ERROR, "unexpected length of salt string");
     360             : 
     361             :     /*-
     362             :      * 1. Start digest A
     363             :      * 2. Add the password string to digest A
     364             :      * 3. Add the salt to digest A
     365             :      */
     366          52 :     px_md_update(digestA, (const unsigned char *) pw, len);
     367          52 :     px_md_update(digestA, (const unsigned char *) decoded_salt->data, salt_len);
     368             : 
     369             :     /*-
     370             :      * 4. Create digest B
     371             :      * 5. Add password to digest B
     372             :      * 6. Add the salt string to digest B
     373             :      * 7. Add the password again to digest B
     374             :      * 8. Finalize digest B
     375             :      */
     376          52 :     px_md_update(digestB, (const unsigned char *) pw, len);
     377          52 :     px_md_update(digestB, (const unsigned char *) dec_salt_binary, salt_len);
     378          52 :     px_md_update(digestB, (const unsigned char *) pw, len);
     379          52 :     px_md_finish(digestB, sha_buf);
     380             : 
     381             :     /*
     382             :      * 9. For each block (excluding the NULL byte), add digest B to digest A.
     383             :      */
     384          62 :     for (block = len; block > buf_size; block -= buf_size)
     385          10 :         px_md_update(digestA, sha_buf, buf_size);
     386             : 
     387             :     /*-
     388             :      * 10. For the remaining N bytes of the password string, add the first N
     389             :      * bytes of digest B to A.
     390             :      */
     391          52 :     px_md_update(digestA, sha_buf, block);
     392             : 
     393             :     /*-
     394             :      * 11. For each bit of the binary representation of the length of the
     395             :      * password string up to and including the highest 1-digit, starting from
     396             :      * to lowest bit position (numeric value 1)
     397             :      *
     398             :      * a) for a 1-digit add digest B (sha_buf) to digest A
     399             :      * b) for a 0-digit add the password string
     400             :      */
     401          52 :     block = len;
     402         272 :     while (block)
     403             :     {
     404         220 :         px_md_update(digestA,
     405             :                      (block & 1) ? sha_buf : (const unsigned char *) pw,
     406             :                      (block & 1) ? buf_size : len);
     407             : 
     408             :         /* right shift to next byte */
     409         220 :         block >>= 1;
     410             :     }
     411             : 
     412             :     /* 12. Finalize digest A */
     413          52 :     px_md_finish(digestA, sha_buf);
     414             : 
     415             :     /* 13. Start digest DP */
     416          52 :     px_md_reset(digestB);
     417             : 
     418             :     /*-
     419             :      * 14 Add every byte of the password string (excluding trailing NULL)
     420             :      * to the digest DP
     421             :      */
     422        1112 :     for (block = len; block > 0; block--)
     423        1060 :         px_md_update(digestB, (const unsigned char *) pw, len);
     424             : 
     425             :     /* 15. Finalize digest DP */
     426          52 :     px_md_finish(digestB, sha_buf_tmp);
     427             : 
     428             :     /*-
     429             :      * 16. produce byte sequence P with same length as password.
     430             :      *     a) for each block of 32 or 64 bytes of length of the password
     431             :      *        string the entire digest DP is used
     432             :      *     b) for the remaining N (up to  31 or 63) bytes use the
     433             :      *        first N bytes of digest DP
     434             :      */
     435          52 :     if ((p_bytes = palloc0(len)) == NULL)
     436             :     {
     437           0 :         goto error;
     438             :     }
     439             : 
     440             :     /* N step of 16, copy over the bytes from password */
     441          62 :     for (cp = p_bytes, block = len; block > buf_size; block -= buf_size, cp += buf_size)
     442          10 :         memcpy(cp, sha_buf_tmp, buf_size);
     443          52 :     memcpy(cp, sha_buf_tmp, block);
     444             : 
     445             :     /*
     446             :      * 17. Start digest DS
     447             :      */
     448          52 :     px_md_reset(digestB);
     449             : 
     450             :     /*-
     451             :      * 18. Repeat the following 16+A[0] times, where A[0] represents the first
     452             :      *    byte in digest A interpreted as an 8-bit unsigned value
     453             :      *    add the salt to digest DS
     454             :      */
     455        7358 :     for (block = 16 + sha_buf[0]; block > 0; block--)
     456        7306 :         px_md_update(digestB, (const unsigned char *) dec_salt_binary, salt_len);
     457             : 
     458             :     /*
     459             :      * 19. Finalize digest DS
     460             :      */
     461          52 :     px_md_finish(digestB, sha_buf_tmp);
     462             : 
     463             :     /*-
     464             :      * 20. Produce byte sequence S of the same length as the salt string where
     465             :      *
     466             :      * a) for each block of 32 or 64 bytes of length of the salt string the
     467             :      *    entire digest DS is used
     468             :      *
     469             :      * b) for the remaining N (up to  31 or 63) bytes use the first N
     470             :      *    bytes of digest DS
     471             :      */
     472          52 :     if ((s_bytes = palloc0(salt_len)) == NULL)
     473           0 :         goto error;
     474             : 
     475          52 :     for (cp = s_bytes, block = salt_len; block > buf_size; block -= buf_size, cp += buf_size)
     476           0 :         memcpy(cp, sha_buf_tmp, buf_size);
     477          52 :     memcpy(cp, sha_buf_tmp, block);
     478             : 
     479             :     /* Make sure we don't leave something important behind */
     480          52 :     px_memset(&sha_buf_tmp, 0, sizeof sha_buf);
     481             : 
     482             :     /*-
     483             :      * 21. Repeat a loop according to the number specified in the rounds=<N>
     484             :      *     specification in the salt (or the default value if none is
     485             :      *     present).  Each round is numbered, starting with 0 and up to N-1.
     486             :      *
     487             :      *     The loop uses a digest as input.  In the first round it is the
     488             :      *     digest produced in step 12.  In the latter steps it is the digest
     489             :      *     produced in step 21.h of the previous round.  The following text
     490             :      *     uses the notation "digest A/B" to describe this behavior.
     491             :      */
     492     1054576 :     for (block = 0; block < rounds; block++)
     493             :     {
     494             :         /*
     495             :          * Make it possible to abort in case large values for "rounds" are
     496             :          * specified.
     497             :          */
     498     1054524 :         CHECK_FOR_INTERRUPTS();
     499             : 
     500             :         /* a) start digest B */
     501     1054524 :         px_md_reset(digestB);
     502             : 
     503             :         /*-
     504             :          * b) for odd round numbers add the byte sequence P to digest B
     505             :          * c) for even round numbers add digest A/B
     506             :          */
     507     1054524 :         px_md_update(digestB,
     508             :                      (block & 1) ? (const unsigned char *) p_bytes : sha_buf,
     509             :                      (block & 1) ? len : buf_size);
     510             : 
     511             :         /* d) for all round numbers not divisible by 3 add the byte sequence S */
     512     1054524 :         if ((block % 3) != 0)
     513      703000 :             px_md_update(digestB, (const unsigned char *) s_bytes, salt_len);
     514             : 
     515             :         /* e) for all round numbers not divisible by 7 add the byte sequence P */
     516     1054524 :         if ((block % 7) != 0)
     517      903852 :             px_md_update(digestB, (const unsigned char *) p_bytes, len);
     518             : 
     519             :         /*-
     520             :          * f) for odd round numbers add digest A/C
     521             :          * g) for even round numbers add the byte sequence P
     522             :          */
     523     1054524 :         px_md_update(digestB,
     524             :                      (block & 1) ? sha_buf : (const unsigned char *) p_bytes,
     525             :                      (block & 1) ? buf_size : len);
     526             : 
     527             :         /* h) finish digest C. */
     528     1054524 :         px_md_finish(digestB, sha_buf);
     529             :     }
     530             : 
     531          52 :     px_md_free(digestA);
     532          52 :     px_md_free(digestB);
     533             : 
     534          52 :     digestA = NULL;
     535          52 :     digestB = NULL;
     536             : 
     537          52 :     pfree(s_bytes);
     538          52 :     pfree(p_bytes);
     539             : 
     540          52 :     s_bytes = NULL;
     541          52 :     p_bytes = NULL;
     542             : 
     543             :     /* prepare final result buffer */
     544          52 :     appendStringInfoCharMacro(out_buf, '$');
     545             : 
     546             : #define b64_from_24bit(B2, B1, B0, N)                                    \
     547             :     do {                                                                 \
     548             :         unsigned int w = ((B2) << 16) | ((B1) << 8) | (B0);              \
     549             :         int     i = (N);                                                 \
     550             :         while (i-- > 0)                                                  \
     551             :         {                                                                \
     552             :             appendStringInfoCharMacro(out_buf, _crypt_itoa64[w & 0x3f]); \
     553             :             w >>= 6;                                                     \
     554             :         }                                                                \
     555             :     } while (0)
     556             : 
     557          52 :     switch (type)
     558             :     {
     559          26 :         case PGCRYPTO_SHA256CRYPT:
     560             :             {
     561         130 :                 b64_from_24bit(sha_buf[0], sha_buf[10], sha_buf[20], 4);
     562         130 :                 b64_from_24bit(sha_buf[21], sha_buf[1], sha_buf[11], 4);
     563         130 :                 b64_from_24bit(sha_buf[12], sha_buf[22], sha_buf[2], 4);
     564         130 :                 b64_from_24bit(sha_buf[3], sha_buf[13], sha_buf[23], 4);
     565         130 :                 b64_from_24bit(sha_buf[24], sha_buf[4], sha_buf[14], 4);
     566         130 :                 b64_from_24bit(sha_buf[15], sha_buf[25], sha_buf[5], 4);
     567         130 :                 b64_from_24bit(sha_buf[6], sha_buf[16], sha_buf[26], 4);
     568         130 :                 b64_from_24bit(sha_buf[27], sha_buf[7], sha_buf[17], 4);
     569         130 :                 b64_from_24bit(sha_buf[18], sha_buf[28], sha_buf[8], 4);
     570         130 :                 b64_from_24bit(sha_buf[9], sha_buf[19], sha_buf[29], 4);
     571         104 :                 b64_from_24bit(0, sha_buf[31], sha_buf[30], 3);
     572             : 
     573          26 :                 break;
     574             :             }
     575             : 
     576          26 :         case PGCRYPTO_SHA512CRYPT:
     577             :             {
     578         130 :                 b64_from_24bit(sha_buf[0], sha_buf[21], sha_buf[42], 4);
     579         130 :                 b64_from_24bit(sha_buf[22], sha_buf[43], sha_buf[1], 4);
     580         130 :                 b64_from_24bit(sha_buf[44], sha_buf[2], sha_buf[23], 4);
     581         130 :                 b64_from_24bit(sha_buf[3], sha_buf[24], sha_buf[45], 4);
     582         130 :                 b64_from_24bit(sha_buf[25], sha_buf[46], sha_buf[4], 4);
     583         130 :                 b64_from_24bit(sha_buf[47], sha_buf[5], sha_buf[26], 4);
     584         130 :                 b64_from_24bit(sha_buf[6], sha_buf[27], sha_buf[48], 4);
     585         130 :                 b64_from_24bit(sha_buf[28], sha_buf[49], sha_buf[7], 4);
     586         130 :                 b64_from_24bit(sha_buf[50], sha_buf[8], sha_buf[29], 4);
     587         130 :                 b64_from_24bit(sha_buf[9], sha_buf[30], sha_buf[51], 4);
     588         130 :                 b64_from_24bit(sha_buf[31], sha_buf[52], sha_buf[10], 4);
     589         130 :                 b64_from_24bit(sha_buf[53], sha_buf[11], sha_buf[32], 4);
     590         130 :                 b64_from_24bit(sha_buf[12], sha_buf[33], sha_buf[54], 4);
     591         130 :                 b64_from_24bit(sha_buf[34], sha_buf[55], sha_buf[13], 4);
     592         130 :                 b64_from_24bit(sha_buf[56], sha_buf[14], sha_buf[35], 4);
     593         130 :                 b64_from_24bit(sha_buf[15], sha_buf[36], sha_buf[57], 4);
     594         130 :                 b64_from_24bit(sha_buf[37], sha_buf[58], sha_buf[16], 4);
     595         130 :                 b64_from_24bit(sha_buf[59], sha_buf[17], sha_buf[38], 4);
     596         130 :                 b64_from_24bit(sha_buf[18], sha_buf[39], sha_buf[60], 4);
     597         130 :                 b64_from_24bit(sha_buf[40], sha_buf[61], sha_buf[19], 4);
     598         130 :                 b64_from_24bit(sha_buf[62], sha_buf[20], sha_buf[41], 4);
     599          78 :                 b64_from_24bit(0, 0, sha_buf[63], 2);
     600             : 
     601          26 :                 break;
     602             :             }
     603             : 
     604           0 :         case PGCRYPTO_SHA_UNKOWN:
     605             :             /* we shouldn't land here ... */
     606           0 :             elog(ERROR, "unsupported digest length");
     607             :     }
     608             : 
     609             :     /*
     610             :      * Copy over result to specified buffer.
     611             :      *
     612             :      * The passwd character buffer should have at least PX_SHACRYPT_BUF_LEN
     613             :      * allocated, since we checked above if dstlen is smaller than
     614             :      * PX_SHACRYPT_BUF_LEN (which also includes the NULL byte).
     615             :      *
     616             :      * In that case we would have failed above already.
     617             :      */
     618          52 :     memcpy(passwd, out_buf->data, out_buf->len);
     619             : 
     620             :     /* make sure nothing important is left behind */
     621          52 :     px_memset(&sha_buf, 0, sizeof sha_buf);
     622          52 :     destroyStringInfo(out_buf);
     623          52 :     destroyStringInfo(decoded_salt);
     624             : 
     625             :     /* ...and we're done */
     626          52 :     return passwd;
     627             : 
     628           0 : error:
     629           0 :     if (digestA != NULL)
     630           0 :         px_md_free(digestA);
     631             : 
     632           0 :     if (digestB != NULL)
     633           0 :         px_md_free(digestB);
     634             : 
     635           0 :     destroyStringInfo(out_buf);
     636           0 :     destroyStringInfo(decoded_salt);
     637             : 
     638           0 :     ereport(ERROR,
     639             :             errcode(ERRCODE_INTERNAL_ERROR),
     640             :             errmsg("cannot create encrypted password"));
     641             :     return NULL;                /* keep compiler quiet */
     642             : }

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