libmisc/salt.c: Use crypt_gensalt(), if available in libcrypt.
Most Linux distributions, including Fedora and RHEL 8, are shipping with libxcrypt >= 4.0. Since that version of libxcrypt the provided family of crypt_gensalt() functions are able to use automatic entropy drawn from secure system ressources, like arc4random(), getentropy() or getrandom(). Anyways, the settings generated by crypt_gensalt() are always guaranteed to works with the crypt() function. Using crypt_gensalt() is also needed to make proper use of newer hashing methods, like yescrypt, provided by libxcrypt. Signed-off-by: Björn Esser <besser82@fedoraproject.org>
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Björn Esser
parent
c93897a8d7
commit
ea04eb301d
132
libmisc/salt.c
132
libmisc/salt.c
@ -22,6 +22,13 @@
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#include "defines.h"
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#include "getdef.h"
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#if (defined CRYPT_GENSALT_IMPLEMENTS_AUTO_ENTROPY && \
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CRYPT_GENSALT_IMPLEMENTS_AUTO_ENTROPY)
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#define USE_XCRYPT_GENSALT 1
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#else
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#define USE_XCRYPT_GENSALT 0
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#endif
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/* Add the salt prefix. */
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#define MAGNUM(array,ch) (array)[0]=(array)[2]='$',(array)[1]=(ch),(array)[3]='\0'
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@ -77,21 +84,26 @@
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/* local function prototypes */
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static long read_random_bytes (void);
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#if !USE_XCRYPT_GENSALT
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static /*@observer@*/const char *gensalt (size_t salt_size);
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#endif /* !USE_XCRYPT_GENSALT */
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#if defined(USE_SHA_CRYPT) || defined(USE_BCRYPT)
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static long shadow_random (long min, long max);
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#endif /* USE_SHA_CRYPT || USE_BCRYPT */
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#ifdef USE_SHA_CRYPT
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static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds);
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static /*@observer@*/const unsigned long SHA_get_salt_rounds (/*@null@*/int *prefered_rounds);
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static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, unsigned long rounds);
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#endif /* USE_SHA_CRYPT */
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#ifdef USE_BCRYPT
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static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds);
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static /*@observer@*/const unsigned long BCRYPT_get_salt_rounds (/*@null@*/int *prefered_rounds);
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static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, unsigned long rounds);
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#endif /* USE_BCRYPT */
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#ifdef USE_YESCRYPT
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static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, /*@null@*/int *prefered_cost);
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static /*@observer@*/const unsigned long YESCRYPT_get_salt_cost (/*@null@*/int *prefered_cost);
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static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, unsigned long cost);
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#endif /* USE_YESCRYPT */
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#ifndef HAVE_L64A
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#if !USE_XCRYPT_GENSALT && !defined(HAVE_L64A)
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static /*@observer@*/char *l64a (long value)
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{
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static char buf[8];
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@ -125,7 +137,7 @@ static /*@observer@*/char *l64a (long value)
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return buf;
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}
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#endif /* !HAVE_L64A */
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#endif /* !USE_XCRYPT_GENSALT && !defined(HAVE_L64A) */
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/* Read sizeof (long) random bytes from /dev/urandom. */
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static long read_random_bytes (void)
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@ -199,14 +211,10 @@ static long shadow_random (long min, long max)
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#endif /* USE_SHA_CRYPT || USE_BCRYPT */
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#ifdef USE_SHA_CRYPT
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/*
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* Fill a salt prefix specifying the rounds number for the SHA crypt methods
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* to a buffer.
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*/
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static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds)
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/* Return the the rounds number for the SHA crypt methods. */
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static /*@observer@*/const unsigned long SHA_get_salt_rounds (/*@null@*/int *prefered_rounds)
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{
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unsigned long rounds;
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const size_t buf_begin = strlen (buf);
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if (NULL == prefered_rounds) {
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long min_rounds = getdef_long ("SHA_CRYPT_MIN_ROUNDS", -1);
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@ -245,6 +253,17 @@ static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, /*@null@*/int *pref
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rounds = SHA_ROUNDS_MAX;
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}
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return rounds;
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}
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/*
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* Fill a salt prefix specifying the rounds number for the SHA crypt methods
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* to a buffer.
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*/
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static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, unsigned long rounds)
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{
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const size_t buf_begin = strlen (buf);
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/* Nothing to do here if SHA_ROUNDS_DEFAULT is used. */
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if (rounds == SHA_ROUNDS_DEFAULT) {
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return;
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@ -265,14 +284,10 @@ static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, /*@null@*/int *pref
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#endif /* USE_SHA_CRYPT */
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#ifdef USE_BCRYPT
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/*
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* Fill a salt prefix specifying the rounds number for the BCRYPT method
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* to a buffer.
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*/
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static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds)
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/* Return the the rounds number for the BCRYPT method. */
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static /*@observer@*/const unsigned long BCRYPT_get_salt_rounds (/*@null@*/int *prefered_rounds)
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{
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unsigned long rounds;
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const size_t buf_begin = strlen (buf);
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if (NULL == prefered_rounds) {
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long min_rounds = getdef_long ("BCRYPT_MIN_ROUNDS", -1);
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@ -306,6 +321,11 @@ static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *p
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rounds = B_ROUNDS_MIN;
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}
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#if USE_XCRYPT_GENSALT
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if (rounds > B_ROUNDS_MAX) {
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rounds = B_ROUNDS_MAX;
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}
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#else /* USE_XCRYPT_GENSALT */
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/*
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* Use 19 as an upper bound for now,
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* because musl doesn't allow rounds >= 20.
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@ -314,6 +334,18 @@ static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *p
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/* rounds = B_ROUNDS_MAX; */
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rounds = 19;
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}
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#endif /* USE_XCRYPT_GENSALT */
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return rounds;
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}
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/*
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* Fill a salt prefix specifying the rounds number for the BCRYPT method
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* to a buffer.
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*/
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static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, unsigned long rounds)
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{
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const size_t buf_begin = strlen (buf);
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/*
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* Check if the result buffer is long enough.
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@ -330,14 +362,10 @@ static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *p
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#endif /* USE_BCRYPT */
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#ifdef USE_YESCRYPT
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/*
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* Fill a salt prefix specifying the cost for the YESCRYPT method
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* to a buffer.
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*/
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static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, /*@null@*/int *prefered_cost)
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/* Return the the cost number for the YESCRYPT method. */
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static /*@observer@*/const unsigned long YESCRYPT_get_salt_cost (/*@null@*/int *prefered_cost)
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{
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unsigned long cost;
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const size_t buf_begin = strlen (buf);
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if (NULL == prefered_cost) {
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cost = getdef_num ("YESCRYPT_COST_FACTOR", Y_COST_DEFAULT);
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@ -356,6 +384,17 @@ static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, /*@null@*/int *p
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cost = Y_COST_MAX;
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}
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return cost;
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}
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/*
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* Fill a salt prefix specifying the cost for the YESCRYPT method
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* to a buffer.
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*/
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static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, unsigned long cost)
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{
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const size_t buf_begin = strlen (buf);
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/*
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* Check if the result buffer is long enough.
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* We are going to write four bytes,
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@ -380,6 +419,7 @@ static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, /*@null@*/int *p
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}
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#endif /* USE_YESCRYPT */
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#if !USE_XCRYPT_GENSALT
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static /*@observer@*/const char *gensalt (size_t salt_size)
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{
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static char salt[MAX_SALT_SIZE + 6];
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@ -397,6 +437,7 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
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return salt;
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}
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#endif /* !USE_XCRYPT_GENSALT */
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/*
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* Generate 8 base64 ASCII characters of random salt. If MD5_CRYPT_ENAB
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@ -420,6 +461,7 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
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static char result[GENSALT_SETTING_SIZE];
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size_t salt_len = MAX_SALT_SIZE;
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const char *method;
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unsigned long rounds = 0;
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memset (result, '\0', GENSALT_SETTING_SIZE);
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@ -435,27 +477,32 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
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if (0 == strcmp (method, "MD5")) {
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MAGNUM(result, '1');
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salt_len = MD5_CRYPT_SALT_SIZE;
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rounds = 0;
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#ifdef USE_BCRYPT
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} else if (0 == strcmp (method, "BCRYPT")) {
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BCRYPTMAGNUM(result);
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salt_len = BCRYPT_SALT_SIZE;
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BCRYPT_salt_rounds_to_buf (result, (int *) arg);
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rounds = BCRYPT_get_salt_rounds ((int *) arg);
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BCRYPT_salt_rounds_to_buf (result, rounds);
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#endif /* USE_BCRYPT */
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#ifdef USE_YESCRYPT
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} else if (0 == strcmp (method, "YESCRYPT")) {
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MAGNUM(result, 'y');
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salt_len = YESCRYPT_SALT_SIZE;
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YESCRYPT_salt_cost_to_buf (result, (int *) arg);
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rounds = YESCRYPT_get_salt_cost ((int *) arg);
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YESCRYPT_salt_cost_to_buf (result, rounds);
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#endif /* USE_YESCRYPT */
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#ifdef USE_SHA_CRYPT
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} else if (0 == strcmp (method, "SHA256")) {
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MAGNUM(result, '5');
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salt_len = SHA_CRYPT_SALT_SIZE;
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SHA_salt_rounds_to_buf (result, (int *) arg);
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rounds = SHA_get_salt_rounds ((int *) arg);
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SHA_salt_rounds_to_buf (result, rounds);
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} else if (0 == strcmp (method, "SHA512")) {
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MAGNUM(result, '6');
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salt_len = SHA_CRYPT_SALT_SIZE;
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SHA_salt_rounds_to_buf (result, (int *) arg);
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rounds = SHA_get_salt_rounds ((int *) arg);
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SHA_salt_rounds_to_buf (result, rounds);
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#endif /* USE_SHA_CRYPT */
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} else if (0 != strcmp (method, "DES")) {
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fprintf (shadow_logfd,
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@ -463,9 +510,39 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
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"Defaulting to DES.\n"),
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method);
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salt_len = MAX_SALT_SIZE;
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rounds = 0;
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memset (result, '\0', GENSALT_SETTING_SIZE);
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}
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#if USE_XCRYPT_GENSALT
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/*
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* Prepare DES setting for crypt_gensalt(), if result
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* has not been filled with anything previously.
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*/
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if ('\0' == result[0]) {
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/* Avoid -Wunused-but-set-variable. */
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salt_len = GENSALT_SETTING_SIZE - 1;
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rounds = 0;
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memset (result, '.', salt_len);
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result[salt_len] = '\0';
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}
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char *retval = crypt_gensalt (result, rounds, NULL, 0);
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/* Should not happen, but... */
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if (NULL == retval) {
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fprintf (shadow_logfd,
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_("Unable to generate a salt from setting "
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"\"%s\", check your settings in "
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"ENCRYPT_METHOD and the corresponding "
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"configuration for your selected hash "
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"method.\n"), result);
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exit (1);
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}
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return retval;
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#else /* USE_XCRYPT_GENSALT */
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/* Check if the result buffer is long enough. */
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assert (GENSALT_SETTING_SIZE > strlen (result) + salt_len);
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@ -474,4 +551,5 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
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GENSALT_SETTING_SIZE - strlen (result) - 1);
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return result;
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#endif /* USE_XCRYPT_GENSALT */
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}
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