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shadow-utils/shadow-4.8.1-crypt_gensalt....

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From ea04eb301d08c0c58f1120f87d4ec184d3983ce5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Esser?= <besser82@fedoraproject.org>
Date: Tue, 15 Jun 2021 14:23:42 +0200
Subject: [PATCH] libmisc/salt.c: Use crypt_gensalt(), if available in
libcrypt.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Most Linux distributions, including Fedora and RHEL 8, are shipping
with libxcrypt >= 4.0.
Since that version of libxcrypt the provided family of crypt_gensalt()
functions are able to use automatic entropy drawn from secure system
ressources, like arc4random(), getentropy() or getrandom().
Anyways, the settings generated by crypt_gensalt() are always
guaranteed to works with the crypt() function.
Using crypt_gensalt() is also needed to make proper use of newer
hashing methods, like yescrypt, provided by libxcrypt.
Signed-off-by: Björn Esser <besser82@fedoraproject.org>
---
libmisc/salt.c | 132 +++++++++++++++++++++++++++++++++++++++----------
1 file changed, 105 insertions(+), 27 deletions(-)
diff --git a/libmisc/salt.c b/libmisc/salt.c
index 13408a53..9fd34332 100644
--- a/libmisc/salt.c
+++ b/libmisc/salt.c
@@ -22,6 +22,13 @@
#include "defines.h"
#include "getdef.h"
+#if (defined CRYPT_GENSALT_IMPLEMENTS_AUTO_ENTROPY && \
+ CRYPT_GENSALT_IMPLEMENTS_AUTO_ENTROPY)
+#define USE_XCRYPT_GENSALT 1
+#else
+#define USE_XCRYPT_GENSALT 0
+#endif
+
/* Add the salt prefix. */
#define MAGNUM(array,ch) (array)[0]=(array)[2]='$',(array)[1]=(ch),(array)[3]='\0'
@@ -77,21 +84,26 @@
/* local function prototypes */
static long read_random_bytes (void);
+#if !USE_XCRYPT_GENSALT
static /*@observer@*/const char *gensalt (size_t salt_size);
+#endif /* !USE_XCRYPT_GENSALT */
#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@*/void SHA_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds);
+static /*@observer@*/const unsigned long SHA_get_salt_rounds (/*@null@*/int *prefered_rounds);
+static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, unsigned long rounds);
#endif /* USE_SHA_CRYPT */
#ifdef USE_BCRYPT
-static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds);
+static /*@observer@*/const unsigned long BCRYPT_get_salt_rounds (/*@null@*/int *prefered_rounds);
+static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, unsigned long rounds);
#endif /* USE_BCRYPT */
#ifdef USE_YESCRYPT
-static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, /*@null@*/int *prefered_cost);
+static /*@observer@*/const unsigned long YESCRYPT_get_salt_cost (/*@null@*/int *prefered_cost);
+static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, unsigned long cost);
#endif /* USE_YESCRYPT */
-#ifndef HAVE_L64A
+#if !USE_XCRYPT_GENSALT && !defined(HAVE_L64A)
static /*@observer@*/char *l64a (long value)
{
static char buf[8];
@@ -125,7 +137,7 @@ static /*@observer@*/char *l64a (long value)
return buf;
}
-#endif /* !HAVE_L64A */
+#endif /* !USE_XCRYPT_GENSALT && !defined(HAVE_L64A) */
/* Read sizeof (long) random bytes from /dev/urandom. */
static long read_random_bytes (void)
@@ -199,14 +211,10 @@ static long shadow_random (long min, long max)
#endif /* USE_SHA_CRYPT || USE_BCRYPT */
#ifdef USE_SHA_CRYPT
-/*
- * Fill a salt prefix specifying the rounds number for the SHA crypt methods
- * to a buffer.
- */
-static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds)
+/* Return the the rounds number for the SHA crypt methods. */
+static /*@observer@*/const unsigned long SHA_get_salt_rounds (/*@null@*/int *prefered_rounds)
{
unsigned long rounds;
- const size_t buf_begin = strlen (buf);
if (NULL == prefered_rounds) {
long min_rounds = getdef_long ("SHA_CRYPT_MIN_ROUNDS", -1);
@@ -245,6 +253,17 @@ static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, /*@null@*/int *pref
rounds = SHA_ROUNDS_MAX;
}
+ return rounds;
+}
+
+/*
+ * Fill a salt prefix specifying the rounds number for the SHA crypt methods
+ * to a buffer.
+ */
+static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, unsigned long rounds)
+{
+ const size_t buf_begin = strlen (buf);
+
/* Nothing to do here if SHA_ROUNDS_DEFAULT is used. */
if (rounds == SHA_ROUNDS_DEFAULT) {
return;
@@ -265,14 +284,10 @@ static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, /*@null@*/int *pref
#endif /* USE_SHA_CRYPT */
#ifdef USE_BCRYPT
-/*
- * Fill a salt prefix specifying the rounds number for the BCRYPT method
- * to a buffer.
- */
-static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds)
+/* Return the the rounds number for the BCRYPT method. */
+static /*@observer@*/const unsigned long BCRYPT_get_salt_rounds (/*@null@*/int *prefered_rounds)
{
unsigned long rounds;
- const size_t buf_begin = strlen (buf);
if (NULL == prefered_rounds) {
long min_rounds = getdef_long ("BCRYPT_MIN_ROUNDS", -1);
@@ -306,6 +321,11 @@ static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *p
rounds = B_ROUNDS_MIN;
}
+#if USE_XCRYPT_GENSALT
+ if (rounds > B_ROUNDS_MAX) {
+ rounds = B_ROUNDS_MAX;
+ }
+#else /* USE_XCRYPT_GENSALT */
/*
* Use 19 as an upper bound for now,
* because musl doesn't allow rounds >= 20.
@@ -314,6 +334,18 @@ static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *p
/* rounds = B_ROUNDS_MAX; */
rounds = 19;
}
+#endif /* USE_XCRYPT_GENSALT */
+
+ return rounds;
+}
+
+/*
+ * Fill a salt prefix specifying the rounds number for the BCRYPT method
+ * to a buffer.
+ */
+static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, unsigned long rounds)
+{
+ const size_t buf_begin = strlen (buf);
/*
* Check if the result buffer is long enough.
@@ -330,14 +362,10 @@ static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *p
#endif /* USE_BCRYPT */
#ifdef USE_YESCRYPT
-/*
- * Fill a salt prefix specifying the cost for the YESCRYPT method
- * to a buffer.
- */
-static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, /*@null@*/int *prefered_cost)
+/* Return the the cost number for the YESCRYPT method. */
+static /*@observer@*/const unsigned long YESCRYPT_get_salt_cost (/*@null@*/int *prefered_cost)
{
unsigned long cost;
- const size_t buf_begin = strlen (buf);
if (NULL == prefered_cost) {
cost = getdef_num ("YESCRYPT_COST_FACTOR", Y_COST_DEFAULT);
@@ -356,6 +384,17 @@ static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, /*@null@*/int *p
cost = Y_COST_MAX;
}
+ return cost;
+}
+
+/*
+ * Fill a salt prefix specifying the cost for the YESCRYPT method
+ * to a buffer.
+ */
+static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, unsigned long cost)
+{
+ const size_t buf_begin = strlen (buf);
+
/*
* Check if the result buffer is long enough.
* We are going to write four bytes,
@@ -380,6 +419,7 @@ static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, /*@null@*/int *p
}
#endif /* USE_YESCRYPT */
+#if !USE_XCRYPT_GENSALT
static /*@observer@*/const char *gensalt (size_t salt_size)
{
static char salt[MAX_SALT_SIZE + 6];
@@ -397,6 +437,7 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
return salt;
}
+#endif /* !USE_XCRYPT_GENSALT */
/*
* Generate 8 base64 ASCII characters of random salt. If MD5_CRYPT_ENAB
@@ -420,6 +461,7 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
static char result[GENSALT_SETTING_SIZE];
size_t salt_len = MAX_SALT_SIZE;
const char *method;
+ unsigned long rounds = 0;
memset (result, '\0', GENSALT_SETTING_SIZE);
@@ -435,27 +477,32 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
if (0 == strcmp (method, "MD5")) {
MAGNUM(result, '1');
salt_len = MD5_CRYPT_SALT_SIZE;
+ rounds = 0;
#ifdef USE_BCRYPT
} else if (0 == strcmp (method, "BCRYPT")) {
BCRYPTMAGNUM(result);
salt_len = BCRYPT_SALT_SIZE;
- BCRYPT_salt_rounds_to_buf (result, (int *) arg);
+ rounds = BCRYPT_get_salt_rounds ((int *) arg);
+ BCRYPT_salt_rounds_to_buf (result, rounds);
#endif /* USE_BCRYPT */
#ifdef USE_YESCRYPT
} else if (0 == strcmp (method, "YESCRYPT")) {
MAGNUM(result, 'y');
salt_len = YESCRYPT_SALT_SIZE;
- YESCRYPT_salt_cost_to_buf (result, (int *) arg);
+ rounds = YESCRYPT_get_salt_cost ((int *) arg);
+ YESCRYPT_salt_cost_to_buf (result, rounds);
#endif /* USE_YESCRYPT */
#ifdef USE_SHA_CRYPT
} else if (0 == strcmp (method, "SHA256")) {
MAGNUM(result, '5');
salt_len = SHA_CRYPT_SALT_SIZE;
- SHA_salt_rounds_to_buf (result, (int *) arg);
+ rounds = SHA_get_salt_rounds ((int *) arg);
+ SHA_salt_rounds_to_buf (result, rounds);
} else if (0 == strcmp (method, "SHA512")) {
MAGNUM(result, '6');
salt_len = SHA_CRYPT_SALT_SIZE;
- SHA_salt_rounds_to_buf (result, (int *) arg);
+ rounds = SHA_get_salt_rounds ((int *) arg);
+ SHA_salt_rounds_to_buf (result, rounds);
#endif /* USE_SHA_CRYPT */
} else if (0 != strcmp (method, "DES")) {
fprintf (shadow_logfd,
@@ -463,9 +510,39 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
"Defaulting to DES.\n"),
method);
salt_len = MAX_SALT_SIZE;
+ rounds = 0;
memset (result, '\0', GENSALT_SETTING_SIZE);
}
+#if USE_XCRYPT_GENSALT
+ /*
+ * Prepare DES setting for crypt_gensalt(), if result
+ * has not been filled with anything previously.
+ */
+ if ('\0' == result[0]) {
+ /* Avoid -Wunused-but-set-variable. */
+ salt_len = GENSALT_SETTING_SIZE - 1;
+ rounds = 0;
+ memset (result, '.', salt_len);
+ result[salt_len] = '\0';
+ }
+
+ char *retval = crypt_gensalt (result, rounds, NULL, 0);
+
+ /* Should not happen, but... */
+ if (NULL == retval) {
+ fprintf (shadow_logfd,
+ _("Unable to generate a salt from setting "
+ "\"%s\", check your settings in "
+ "ENCRYPT_METHOD and the corresponding "
+ "configuration for your selected hash "
+ "method.\n"), result);
+
+ exit (1);
+ }
+
+ return retval;
+#else /* USE_XCRYPT_GENSALT */
/* Check if the result buffer is long enough. */
assert (GENSALT_SETTING_SIZE > strlen (result) + salt_len);
@@ -474,4 +551,5 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
GENSALT_SETTING_SIZE - strlen (result) - 1);
return result;
+#endif /* USE_XCRYPT_GENSALT */
}
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