8f796e40a5
We would reject various passwords that glibc accepts, for example "" or any descrypted password. Accounts with empty password are definitely useful, for example for testing or in scenarios where a password is not needed. Also, using weak encryption methods is probably not a good idea, it's not the job of our nss helpers to decide that: they should just faithfully forward whatever data is there. Also rename the function to make it more obvious that the returned answer is not in any way certain.
92 lines
2.7 KiB
C
92 lines
2.7 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <errno.h>
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#include <stdlib.h>
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#include "alloc-util.h"
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#include "libcrypt-util.h"
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#include "log.h"
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#include "macro.h"
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#include "missing_stdlib.h"
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#include "random-util.h"
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#include "string-util.h"
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#include "strv.h"
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int make_salt(char **ret) {
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#ifdef XCRYPT_VERSION_MAJOR
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const char *e;
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char *salt;
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/* If we have libxcrypt we default to the "preferred method" (i.e. usually yescrypt), and generate it
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* with crypt_gensalt_ra(). */
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e = secure_getenv("SYSTEMD_CRYPT_PREFIX");
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if (!e)
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e = crypt_preferred_method();
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log_debug("Generating salt for hash prefix: %s", e);
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salt = crypt_gensalt_ra(e, 0, NULL, 0);
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if (!salt)
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return -errno;
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*ret = salt;
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return 0;
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#else
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/* If libxcrypt is not used, we use SHA512 and generate the salt on our own since crypt_gensalt_ra()
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* is not available. */
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static const char table[] =
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"abcdefghijklmnopqrstuvwxyz"
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"0123456789"
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"./";
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uint8_t raw[16];
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char *salt, *j;
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size_t i;
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int r;
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/* This is a bit like crypt_gensalt_ra(), but doesn't require libcrypt, and doesn't do anything but
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* SHA512, i.e. is legacy-free and minimizes our deps. */
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assert_cc(sizeof(table) == 64U + 1U);
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/* Insist on the best randomness by setting RANDOM_BLOCK, this is about keeping passwords secret after all. */
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r = genuine_random_bytes(raw, sizeof(raw), RANDOM_BLOCK);
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if (r < 0)
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return r;
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salt = new(char, 3+sizeof(raw)+1+1);
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if (!salt)
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return -ENOMEM;
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/* We only bother with SHA512 hashed passwords, the rest is legacy, and we don't do legacy. */
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j = stpcpy(salt, "$6$");
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for (i = 0; i < sizeof(raw); i++)
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j[i] = table[raw[i] & 63];
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j[i++] = '$';
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j[i] = 0;
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*ret = salt;
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return 0;
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#endif
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}
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bool looks_like_hashed_password(const char *s) {
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/* Returns false if the specified string is certainly not a hashed UNIX password. crypt(5) lists
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* various hashing methods. We only reject (return false) strings which are documented to have
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* different meanings.
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*
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* In particular, we allow locked passwords, i.e. strings starting with "!", including just "!",
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* i.e. the locked empty password. See also fc58c0c7bf7e4f525b916e3e5be0de2307fef04e.
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*/
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if (!s)
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return false;
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s += strspn(s, "!"); /* Skip (possibly duplicated) locking prefix */
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return !STR_IN_SET(s, "x", "*");
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}
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