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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <errno.h>
#include <stdlib.h>
#include "alloc-util.h"
#include "libcrypt-util.h"
#include "log.h"
#include "macro.h"
#include "missing_stdlib.h"
#include "random-util.h"
#include "string-util.h"
#include "strv.h"
int make_salt(char **ret) {
#ifdef XCRYPT_VERSION_MAJOR
const char *e;
char *salt;
/* If we have libxcrypt we default to the "preferred method" (i.e. usually yescrypt), and generate it
* with crypt_gensalt_ra(). */
e = secure_getenv("SYSTEMD_CRYPT_PREFIX");
if (!e)
e = crypt_preferred_method();
log_debug("Generating salt for hash prefix: %s", e);
salt = crypt_gensalt_ra(e, 0, NULL, 0);
if (!salt)
return -errno;
*ret = salt;
return 0;
#else
/* If libxcrypt is not used, we use SHA512 and generate the salt on our own since crypt_gensalt_ra()
* is not available. */
static const char table[] =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789"
"./";
uint8_t raw[16];
char *salt, *j;
size_t i;
int r;
/* This is a bit like crypt_gensalt_ra(), but doesn't require libcrypt, and doesn't do anything but
* SHA512, i.e. is legacy-free and minimizes our deps. */
assert_cc(sizeof(table) == 64U + 1U);
/* Insist on the best randomness by setting RANDOM_BLOCK, this is about keeping passwords secret after all. */
r = genuine_random_bytes(raw, sizeof(raw), RANDOM_BLOCK);
if (r < 0)
return r;
salt = new(char, 3+sizeof(raw)+1+1);
if (!salt)
return -ENOMEM;
/* We only bother with SHA512 hashed passwords, the rest is legacy, and we don't do legacy. */
j = stpcpy(salt, "$6$");
for (i = 0; i < sizeof(raw); i++)
j[i] = table[raw[i] & 63];
j[i++] = '$';
j[i] = 0;
*ret = salt;
return 0;
#endif
}
bool hashed_password_valid(const char *s) {
/* Returns true if the specified string is a 'valid' hashed UNIX password, i.e. if starts with '$' or
* with '!$' (the latter being a valid, yet locked password). */
if (isempty(s))
return false;
return STARTSWITH_SET(s, "$", "!$");
}
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