libuser/libuser-0.63-PR49_add_yescrypt.patch

From 3b8a2aa52bcee6e03f047840251ae42ab971a8a0 Mon Sep 17 00:00:00 2001
From: Björn Esser <besser82@fedoraproject.org>
Date: Jun 07 2021 20:25:41 +0000
Subject: [PATCH 1/5] lib/util.c: bcrypt should use $2b$ as prefix for setting.


This prefix is the recommended one for new bcrypt hashes
for a long time.

Signed-off-by: Björn Esser <besser82@fedoraproject.org>

---

diff --git a/lib/util.c b/lib/util.c
index 1b03f7d..e549a35 100644
--- a/lib/util.c
+++ b/lib/util.c
@@ -124,7 +124,7 @@ static const struct {
 } salt_type_info[] = {
 	{"$1$", "$", 8, FALSE },
 	/* FIXME: number of rounds, base64 of 128 bits */
-	{"$2a$", "$", 8, FALSE },
+	{"$2b$", "$", 8, FALSE },
 	{"$5$", "$", 16, TRUE },
 	{"$6$", "$", 16, TRUE },
 	{ "", "", 2 },
@@ -231,7 +231,7 @@ lu_util_default_salt_specifier(struct lu_context *context)
 	} salt_types[] = {
 		{ "des", "", FALSE },
 		{ "md5", "$1$", FALSE },
-		{ "blowfish", "$2a$", FALSE },
+		{ "blowfish", "$2b$", FALSE },
 		{ "sha256", "$5$", TRUE },
 		{ "sha512", "$6$", TRUE },
 	};

From 9dcc69425677cf510ec6da5ababfdd295f875c1a Mon Sep 17 00:00:00 2001
From: Björn Esser <besser82@fedoraproject.org>
Date: Jun 17 2021 15:34:02 +0000
Subject: [PATCH 2/5] lib/util.c: Use crypt_gensalt(), if available in libcrypt.


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_gesalt() is also needed to make proper use of newer
hashing methods, like yescrypt, provided by libxcrypt.

Signed-off-by: Björn Esser <besser82@fedoraproject.org>

---

diff --git a/lib/util.c b/lib/util.c
index e549a35..b6db2af 100644
--- a/lib/util.c
+++ b/lib/util.c
@@ -43,6 +43,13 @@
 #define HASH_ROUNDS_MIN 1000
 #define HASH_ROUNDS_MAX 999999999
 
+#if (defined CRYPT_GENSALT_IMPLEMENTS_AUTO_ENTROPY && \
+     CRYPT_GENSALT_IMPLEMENTS_AUTO_ENTROPY)
+#define USE_XCRYPT_GENSALT 1
+#else
+#define USE_XCRYPT_GENSALT 0
+#endif
+
 struct lu_lock {
 	int fd;
 	struct flock lock;
@@ -66,6 +73,7 @@ lu_strcmp(gconstpointer v1, gconstpointer v2)
 	return strcmp((char *) v1, (char *) v2);
 }
 
+#if !USE_XCRYPT_GENSALT
 /* A list of allowed salt characters, according to SUSv2. */
 #define ACCEPTABLE "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
 		   "abcdefghijklmnopqrstuvwxyz" \
@@ -115,6 +123,7 @@ fill_urandom(char *output, size_t length)
 	close(fd);
 	return TRUE;
 }
+#endif
 
 static const struct {
 	const char initial[5];
@@ -135,6 +144,9 @@ lu_make_crypted(const char *plain, const char *previous)
 {
 	char salt[2048];
 	size_t i, len = 0;
+#if USE_XCRYPT_GENSALT
+	unsigned long rounds = 0;
+#endif
 
 	if (previous == NULL) {
 		previous = LU_DEFAULT_SALT_TYPE;
@@ -151,6 +163,23 @@ lu_make_crypted(const char *plain, const char *previous)
 
 	if (salt_type_info[i].sha_rounds != FALSE
 	    && strncmp(previous + len, "rounds=", strlen("rounds=")) == 0) {
+#if USE_XCRYPT_GENSALT
+		const char *start;
+		char *end;
+
+		start = previous + len + strlen("rounds=");
+		rounds = strtoul (start, &end, 10);
+
+		if (rounds < HASH_ROUNDS_MIN)
+			rounds = HASH_ROUNDS_MIN;
+		else if (rounds > HASH_ROUNDS_MAX)
+			rounds = HASH_ROUNDS_MAX;
+	}
+
+	g_assert(CRYPT_GENSALT_OUTPUT_SIZE <= sizeof(salt));
+
+	crypt_gensalt_rn(previous, rounds, NULL, 0, salt, sizeof(salt));
+#else
 		const char *start, *end;
 
 		start = previous + len + strlen("rounds=");
@@ -168,6 +197,7 @@ lu_make_crypted(const char *plain, const char *previous)
 		return NULL;
 	strcpy(salt + len + salt_type_info[i].salt_length,
 	       salt_type_info[i].separator);
+#endif
 
 	return crypt(plain, salt);
 }
@@ -251,13 +281,18 @@ lu_util_default_salt_specifier(struct lu_context *context)
 
 found:
 	if (salt_types[i].sha_rounds != FALSE) {
-		unsigned long rounds;
+		unsigned long rounds = 0;
 
 		rounds = select_hash_rounds(context);
+#if USE_XCRYPT_GENSALT
+		return g_strdup(crypt_gensalt(salt_types[i].initializer,
+					      rounds, NULL, 0));
+#else
 		if (rounds != 0)
 			return g_strdup_printf("%srounds=%lu$",
 					       salt_types[i].initializer,
 					       rounds);
+#endif
 	}
 	return g_strdup(salt_types[i].initializer);
 }

From 2d40503977df3855f1415db995833ae4231e7944 Mon Sep 17 00:00:00 2001
From: Björn Esser <besser82@fedoraproject.org>
Date: Jun 17 2021 15:34:02 +0000
Subject: [PATCH 3/5] lib/util.c: Add yescrypt hashing method for user passwords.


The yescrypt hashing method is considered to be much stronger than
sha512crypt and fully supported by libxcrypt >= 4.3.  It is based
on NIST-approved primitives and on par with argon2 in strength.

Signed-off-by: Björn Esser <besser82@fedoraproject.org>

---

diff --git a/lib/util.c b/lib/util.c
index b6db2af..bba9420 100644
--- a/lib/util.c
+++ b/lib/util.c
@@ -50,6 +50,14 @@
 #define USE_XCRYPT_GENSALT 0
 #endif
 
+#if ((defined XCRYPT_VERSION_NUM && \
+      XCRYPT_VERSION_NUM >= ((4 << 16) | 3)) && \
+      USE_XCRYPT_GENSALT)
+#define HAVE_YESCRYPT 1
+#else
+#define HAVE_YESCRYPT 0
+#endif
+
 struct lu_lock {
 	int fd;
 	struct flock lock;
@@ -136,6 +144,9 @@ static const struct {
 	{"$2b$", "$", 8, FALSE },
 	{"$5$", "$", 16, TRUE },
 	{"$6$", "$", 16, TRUE },
+#if HAVE_YESCRYPT
+	{"$y$", "$", 24, FALSE },
+#endif
 	{ "", "", 2 },
 };
 
@@ -264,6 +275,9 @@ lu_util_default_salt_specifier(struct lu_context *context)
 		{ "blowfish", "$2b$", FALSE },
 		{ "sha256", "$5$", TRUE },
 		{ "sha512", "$6$", TRUE },
+#if HAVE_YESCRYPT
+		{ "yescrypt", "$y$", FALSE },
+#endif
 	};
 
 	const char *salt_type;

From 71ef71fe1878a321612e1995cb5c59dcb501ff01 Mon Sep 17 00:00:00 2001
From: Björn Esser <besser82@fedoraproject.org>
Date: Jun 17 2021 15:34:02 +0000
Subject: [PATCH 4/5] docs/libuser.conf.5.in: Add yescrypt parameter for crypt_style.


Signed-off-by: Björn Esser <besser82@fedoraproject.org>

---

diff --git a/docs/libuser.conf.5.in b/docs/libuser.conf.5.in
index 2af0828..bd1daa7 100644
--- a/docs/libuser.conf.5.in
+++ b/docs/libuser.conf.5.in
@@ -69,8 +69,8 @@ The current algorithm may be retained
 when changing a password of an existing user, depending on the application.
 
 Possible values are \fBdes\fR, \fBmd5\fR, \fBblowfish\fR,
-.B sha256
-and \fBsha512\fR, all case-insensitive.
+.B sha256,
+\fBsha512\fR, and \fByescrypt\fR, all case-insensitive.
 Unrecognized values are treated as \fBdes\fR.
 Default value is \fBdes\fR.
 

From 284b3195393688105b112b905069e0225c3046d2 Mon Sep 17 00:00:00 2001
From: Björn Esser <besser82@fedoraproject.org>
Date: Jun 17 2021 15:34:02 +0000
Subject: [PATCH 5/5] libuser.conf: Use yescrypt as default value for crypt_style.


Signed-off-by: Björn Esser <besser82@fedoraproject.org>

---

diff --git a/libuser.conf b/libuser.conf
index 8ff5b2e..cd25eb2 100644
--- a/libuser.conf
+++ b/libuser.conf
@@ -17,7 +17,7 @@ default_useradd = /etc/default/useradd
 # skeleton = /etc/skel
 # mailspooldir = /var/mail
 
-crypt_style = sha512
+crypt_style = yescrypt
 modules = files shadow
 create_modules = files shadow
 # modules = files shadow ldap