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Initial bcrypt support

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This commit is contained in:
prez
2019-09-16 20:54:56 +02:00
committed by Serge Hallyn
parent 38f493aff2
commit 2958bd050b
10 changed files with 374 additions and 64 deletions
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123
libmisc/salt.c
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@ -22,10 +22,16 @@
/* local function prototypes */
static void seedRNG (void);
static /*@observer@*/const char *gensalt (size_t salt_size);
#ifdef USE_SHA_CRYPT
#if defined(USE_SHA_CRYPT) || defined(USE_BCRYPT)
static long shadow_random (long min, long max);
#endif /* USE_SHA_CRYPT || USE_BCRYPT */
#ifdef USE_SHA_CRYPT
static /*@observer@*/const char *SHA_salt_rounds (/*@null@*/int *prefered_rounds);
#endif /* USE_SHA_CRYPT */
#ifdef USE_BCRYPT
static /*@observer@*/const char *gensalt_bcrypt (void);
static /*@observer@*/const char *BCRYPT_salt_rounds (/*@null@*/int *prefered_rounds);
#endif /* USE_BCRYPT */
#ifndef HAVE_L64A
static /*@observer@*/char *l64a(long value)
@ -79,8 +85,16 @@ static void seedRNG (void)
* Add the salt prefix.
*/
#define MAGNUM(array,ch) (array)[0]=(array)[2]='$',(array)[1]=(ch),(array)[3]='\0'
#ifdef USE_BCRYPT
/*
* Using the Prefix $2a$ to enable an anti-collision safety measure in musl libc.
* Negatively affects a subset of passwords containing the '\xff' character,
* which is not valid UTF-8 (so "unlikely to cause much annoyance").
*/
#define BCRYPTMAGNUM(array) (array)[0]=(array)[3]='$',(array)[1]='2',(array)[2]='a',(array)[4]='\0'
#endif /* USE_BCRYPT */
#ifdef USE_SHA_CRYPT
#if defined(USE_SHA_CRYPT) || defined(USE_BCRYPT)
/* It is not clear what is the maximum value of random().
* We assume 2^31-1.*/
#define RANDOM_MAX 0x7FFFFFFF
@ -105,14 +119,15 @@ static long shadow_random (long min, long max)
}
return ret;
}
#endif /* USE_SHA_CRYPT || USE_BCRYPT */
#ifdef USE_SHA_CRYPT
/* Default number of rounds if not explicitly specified. */
#define ROUNDS_DEFAULT 5000
/* Minimum number of rounds. */
#define ROUNDS_MIN 1000
/* Maximum number of rounds. */
#define ROUNDS_MAX 999999999
/*
* Return a salt prefix specifying the rounds number for the SHA crypt methods.
*/
@ -165,6 +180,89 @@ static /*@observer@*/const char *SHA_salt_rounds (/*@null@*/int *prefered_rounds
}
#endif /* USE_SHA_CRYPT */
#ifdef USE_BCRYPT
/* Default number of rounds if not explicitly specified. */
#define B_ROUNDS_DEFAULT 13
/* Minimum number of rounds. */
#define B_ROUNDS_MIN 4
/* Maximum number of rounds. */
#define B_ROUNDS_MAX 31
/*
* Return a salt prefix specifying the rounds number for the BCRYPT method.
*/
static /*@observer@*/const char *BCRYPT_salt_rounds (/*@null@*/int *prefered_rounds)
{
static char rounds_prefix[4]; /* Max size: 31$ */
long rounds;
if (NULL == prefered_rounds) {
long min_rounds = getdef_long ("BCRYPT_MIN_ROUNDS", -1);
long max_rounds = getdef_long ("BCRYPT_MAX_ROUNDS", -1);
if (((-1 == min_rounds) && (-1 == max_rounds)) || (0 == *prefered_rounds)) {
rounds = B_ROUNDS_DEFAULT;
}
else {
if (-1 == min_rounds) {
min_rounds = max_rounds;
}
if (-1 == max_rounds) {
max_rounds = min_rounds;
}
if (min_rounds > max_rounds) {
max_rounds = min_rounds;
}
rounds = shadow_random (min_rounds, max_rounds);
}
} else {
rounds = *prefered_rounds;
}
/*
* Sanity checks.
* Use 19 as an upper bound for now,
* because musl doesn't allow rounds >= 20.
*/
if (rounds < B_ROUNDS_MIN) {
rounds = B_ROUNDS_MIN;
}
if (rounds > 19) {
/* rounds = B_ROUNDS_MAX; */
rounds = 19;
}
(void) snprintf (rounds_prefix, sizeof rounds_prefix,
"%2.2ld$", rounds);
return rounds_prefix;
}
#define BCRYPT_SALT_SIZE 22
/*
* Generate a 22 character salt string for bcrypt.
*/
static /*@observer@*/const char *gensalt_bcrypt (void)
{
static char salt[32];
salt[0] = '\0';
seedRNG ();
strcat (salt, l64a (random()));
do {
strcat (salt, l64a (random()));
} while (strlen (salt) < BCRYPT_SALT_SIZE);
salt[BCRYPT_SALT_SIZE] = '\0';
return salt;
}
#endif /* USE_BCRYPT */
/*
* Generate salt of size salt_size.
*/
@ -230,6 +328,11 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
if (0 == strcmp (method, "MD5")) {
MAGNUM(result, '1');
#ifdef USE_BCRYPT
} else if (0 == strcmp (method, "BCRYPT")) {
BCRYPTMAGNUM(result);
strcat(result, BCRYPT_salt_rounds((int *)arg));
#endif /* USE_BCRYPT */
#ifdef USE_SHA_CRYPT
} else if (0 == strcmp (method, "SHA256")) {
MAGNUM(result, '5');
@ -252,8 +355,18 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
* Concatenate a pseudo random salt.
*/
assert (sizeof (result) > strlen (result) + salt_len);
strncat (result, gensalt (salt_len),
sizeof (result) - strlen (result) - 1);
#ifdef USE_BCRYPT
if (0 == strcmp (method, "BCRYPT")) {
strncat (result, gensalt_bcrypt (),
sizeof (result) - strlen (result) - 1);
return result;
} else {
#endif /* USE_BCRYPT */
strncat (result, gensalt (salt_len),
sizeof (result) - strlen (result) - 1);
#ifdef USE_BCRYPT
}
#endif /* USE_BCRYPT */
return result;
}