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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#if HAVE_CRYPT_H
/* libxcrypt is a replacement for glibc's libcrypt, and libcrypt might be
* removed from glibc at some point. As part of the removal, defines for
* crypt(3) are dropped from unistd.h, and we must include crypt.h instead.
*
* Newer versions of glibc (v2.0+) already ship crypt.h with a definition
* of crypt(3) as well, so we simply include it if it is present. MariaDB,
* MySQL, PostgreSQL, Perl and some other wide-spread packages do it the
* same way since ages without any problems.
*/
# include <crypt.h>
#else
# include <unistd.h>
#endif
#include <errno.h>
#include <stdlib.h>
#include "alloc-util.h"
#include "errno-util.h"
#include "libcrypt-util.h"
#include "log.h"
#include "macro.h"
#include "memory-util.h"
#include "missing_stdlib.h"
#include "random-util.h"
#include "string-util.h"
#include "strv.h"
int make_salt(char **ret) {
#if HAVE_CRYPT_GENSALT_RA
const char *e;
char *salt;
/* If we have crypt_gensalt_ra() we default to the "preferred method" (i.e. usually yescrypt).
* crypt_gensalt_ra() is usually provided by libxcrypt. */
e = secure_getenv("SYSTEMD_CRYPT_PREFIX");
if (!e)
#if HAVE_CRYPT_PREFERRED_METHOD
e = crypt_preferred_method();
#else
e = "$6$";
#endif
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 crypt_gensalt_ra() is not available, we use SHA512 and generate the salt on our own. */
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);
log_debug("Generating fallback salt for hash prefix: $6$");
/* 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
}
#if HAVE_CRYPT_RA
# define CRYPT_RA_NAME "crypt_ra"
#else
# define CRYPT_RA_NAME "crypt_r"
/* Provide a poor man's fallback that uses a fixed size buffer. */
static char* systemd_crypt_ra(const char *phrase, const char *setting, void **data, int *size) {
assert(data);
assert(size);
/* We allocate the buffer because crypt(3) says: struct crypt_data may be quite large (32kB in this
* implementation of libcrypt; over 128kB in some other implementations). This is large enough that
* it may be unwise to allocate it on the stack. */
if (!*data) {
*data = new0(struct crypt_data, 1);
if (!*data) {
errno = -ENOMEM;
return NULL;
}
*size = (int) (sizeof(struct crypt_data));
}
char *t = crypt_r(phrase, setting, *data);
if (!t)
return NULL;
/* crypt_r may return a pointer to an invalid hashed password on error. Our callers expect NULL on
* error, so let's just return that. */
if (t[0] == '*')
return NULL;
return t;
}
#define crypt_ra systemd_crypt_ra
#endif
int hash_password_full(const char *password, void **cd_data, int *cd_size, char **ret) {
_cleanup_free_ char *salt = NULL;
_cleanup_(erase_and_freep) void *_cd_data = NULL;
char *p;
int r, _cd_size = 0;
assert(!!cd_data == !!cd_size);
r = make_salt(&salt);
if (r < 0)
return log_debug_errno(r, "Failed to generate salt: %m");
errno = 0;
p = crypt_ra(password, salt, cd_data ?: &_cd_data, cd_size ?: &_cd_size);
if (!p)
return log_debug_errno(errno_or_else(SYNTHETIC_ERRNO(EINVAL)),
CRYPT_RA_NAME "() failed: %m");
p = strdup(p);
if (!p)
return -ENOMEM;
*ret = p;
return 0;
}
bool looks_like_hashed_password(const char *s) {
/* Returns false if the specified string is certainly not a hashed UNIX password. crypt(5) lists
* various hashing methods. We only reject (return false) strings which are documented to have
* different meanings.
*
* In particular, we allow locked passwords, i.e. strings starting with "!", including just "!",
* i.e. the locked empty password. See also fc58c0c7bf7e4f525b916e3e5be0de2307fef04e.
*/
if (!s)
return false;
s += strspn(s, "!"); /* Skip (possibly duplicated) locking prefix */
return !STR_IN_SET(s, "x", "*");
}
int test_password_one(const char *hashed_password, const char *password) {
_cleanup_(erase_and_freep) void *cd_data = NULL;
int cd_size = 0;
const char *k;
errno = 0;
k = crypt_ra(password, hashed_password, &cd_data, &cd_size);
if (!k) {
if (errno == ENOMEM)
return -ENOMEM;
/* Unknown or unavailable hashing method or string too short */
return 0;
}
return streq(k, hashed_password);
}
int test_password_many(char **hashed_password, const char *password) {
char **hpw;
int r;
STRV_FOREACH(hpw, hashed_password) {
r = test_password_one(*hpw, password);
if (r < 0)
return r;
if (r > 0)
return true;
}
return false;
}
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