Adding upstream version 247.3.upstream/247.3upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 212 insertions, 0 deletions

diff --git a/src/shared/libcrypt-util.c b/src/shared/libcrypt-util.c
new file mode 100644
index 0000000..5b31541
--- /dev/null
+++ b/src/shared/libcrypt-util.c
@@ -0,0 +1,212 @@
+/* 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;
+}