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Add a patch to cleanup the code in libmisc/salt.c 

Signed-off-by: Björn Esser <besser82@fedoraproject.org>
This commit is contained in:
Björn Esser 2021-06-21 15:01:46 +02:00
parent c0e594d3c5
commit 2615b08c31
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shadow-4.8.1-salt_c_sanitize_code.patch Normal file
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@ -0,0 +1,555 @@
From 14b108728a5d55c3d478a170c39f0e2ffd4de1b0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Esser?= <besser82@fedoraproject.org>
Date: Mon, 14 Jun 2021 23:28:28 +0200
Subject: [PATCH] libmisc/salt.c: Sanitize code.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
* Move all pre-processor defines to the top of the file.
* Unify the gensalt() function to be useable for all supported
hash methods.
* Drop the gensalt_{b,yes}crypt() functions in favor of the
previous change.
* Refactor the functions converting the rounds number into
a string for use with the crypt() function, to not require
any static buffer anymore.
* Clarify the comment about how crypt_make_salt() chooses the used
hash method from the settings in the login.defs file.
* Use memset() to fill static buffers with zero before using them.
* Use a fixed amount of 16 random base64-chars for the
sha{256,512}crypt hash methods, which is effectively still less
than the recommendation from NIST (>= 128 bits), but the maximum
those methods can effectively use (approx. 90 bits).
* Rename ROUNDS_{MIN,MAX} to SHA_ROUNDS_{MIN,MAX}.
* Bugfixes in the logic of setting rounds in BCRYPT_salt_rounds().
* Likewise for YESCRYPT_salt_cost().
* Fix formatting and white-space errors.
Signed-off-by: Björn Esser <besser82@fedoraproject.org>
---
libmisc/salt.c | 332 ++++++++++++++++++++++---------------------------
1 file changed, 147 insertions(+), 185 deletions(-)
diff --git a/libmisc/salt.c b/libmisc/salt.c
index 5dc521ef..98982ed1 100644
--- a/libmisc/salt.c
+++ b/libmisc/salt.c
@@ -12,6 +12,7 @@
#ident "$Id$"
#include <sys/time.h>
+#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
@@ -19,6 +20,59 @@
#include "defines.h"
#include "getdef.h"
+/* Add the salt prefix. */
+#define MAGNUM(array,ch) (array)[0]=(array)[2]='$',(array)[1]=(ch),(array)[3]='\0'
+
+#ifdef USE_BCRYPT
+/* Use $2b$ as prefix for compatibility with OpenBSD's bcrypt. */
+#define BCRYPTMAGNUM(array) (array)[0]=(array)[3]='$',(array)[1]='2',(array)[2]='b',(array)[4]='\0'
+#define BCRYPT_SALT_SIZE 22
+/* Default number of rounds if not explicitly specified. */
+#define B_ROUNDS_DEFAULT 13
+/* Minimum number of rounds. */
+#define B_ROUNDS_MIN 4
+/* Maximum number of rounds. */
+#define B_ROUNDS_MAX 31
+#endif /* USE_BCRYPT */
+
+#ifdef USE_SHA_CRYPT
+/* Fixed salt len for sha{256,512}crypt. */
+#define SHA_CRYPT_SALT_SIZE 16
+/* Default number of rounds if not explicitly specified. */
+#define SHA_ROUNDS_DEFAULT 5000
+/* Minimum number of rounds. */
+#define SHA_ROUNDS_MIN 1000
+/* Maximum number of rounds. */
+#define SHA_ROUNDS_MAX 999999999
+#endif
+
+#ifdef USE_YESCRYPT
+/*
+ * Default number of base64 characters used for the salt.
+ * 24 characters gives a 144 bits (18 bytes) salt. Unlike the more
+ * traditional 128 bits (16 bytes) salt, this 144 bits salt is always
+ * represented by the same number of base64 characters without padding
+ * issue, even with a non-standard base64 encoding scheme.
+ */
+#define YESCRYPT_SALT_SIZE 24
+/* Default cost if not explicitly specified. */
+#define Y_COST_DEFAULT 5
+/* Minimum cost. */
+#define Y_COST_MIN 1
+/* Maximum cost. */
+#define Y_COST_MAX 11
+#endif
+
+/* Fixed salt len for md5crypt. */
+#define MD5_CRYPT_SALT_SIZE 8
+
+/* Generate salt of size salt_size. */
+#define MAX_SALT_SIZE 44
+#define MIN_SALT_SIZE 8
+
+/* Maximum size of the generated salt string. */
+#define GENSALT_SETTING_SIZE 100
+
/* local function prototypes */
static void seedRNG (void);
static /*@observer@*/const char *gensalt (size_t salt_size);
@@ -26,19 +80,17 @@ static /*@observer@*/const char *gensalt (size_t salt_size);
static long shadow_random (long min, long max);
#endif /* USE_SHA_CRYPT || USE_BCRYPT */
#ifdef USE_SHA_CRYPT
-static /*@observer@*/const char *SHA_salt_rounds (/*@null@*/int *prefered_rounds);
+static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds);
#endif /* USE_SHA_CRYPT */
#ifdef USE_BCRYPT
-static /*@observer@*/const char *gensalt_bcrypt (void);
-static /*@observer@*/const char *BCRYPT_salt_rounds (/*@null@*/int *prefered_rounds);
+static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds);
#endif /* USE_BCRYPT */
#ifdef USE_YESCRYPT
-static /*@observer@*/const char *gensalt_yescrypt (void);
-static /*@observer@*/const char *YESCRYPT_salt_cost (/*@null@*/int *prefered_cost);
+static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, /*@null@*/int *prefered_cost);
#endif /* USE_YESCRYPT */
#ifndef HAVE_L64A
-static /*@observer@*/char *l64a(long value)
+static /*@observer@*/char *l64a (long value)
{
static char buf[8];
char *s = buf;
@@ -69,7 +121,7 @@ static /*@observer@*/char *l64a(long value)
*s = '\0';
- return(buf);
+ return buf;
}
#endif /* !HAVE_L64A */
@@ -85,15 +137,6 @@ static void seedRNG (void)
}
}
-/*
- * Add the salt prefix.
- */
-#define MAGNUM(array,ch) (array)[0]=(array)[2]='$',(array)[1]=(ch),(array)[3]='\0'
-#ifdef USE_BCRYPT
-/* Use $2b$ as prefix for compatibility with OpenBSD's bcrypt. */
-#define BCRYPTMAGNUM(array) (array)[0]=(array)[3]='$',(array)[1]='2',(array)[2]='b',(array)[4]='\0'
-#endif /* USE_BCRYPT */
-
#if defined(USE_SHA_CRYPT) || defined(USE_BCRYPT)
/* It is not clear what is the maximum value of random().
* We assume 2^31-1.*/
@@ -122,26 +165,21 @@ static long shadow_random (long min, long max)
#endif /* USE_SHA_CRYPT || USE_BCRYPT */
#ifdef USE_SHA_CRYPT
-/* Default number of rounds if not explicitly specified. */
-#define ROUNDS_DEFAULT 5000
-/* Minimum number of rounds. */
-#define ROUNDS_MIN 1000
-/* Maximum number of rounds. */
-#define ROUNDS_MAX 999999999
/*
- * Return a salt prefix specifying the rounds number for the SHA crypt methods.
+ * Fill a salt prefix specifying the rounds number for the SHA crypt methods
+ * to a buffer.
*/
-static /*@observer@*/const char *SHA_salt_rounds (/*@null@*/int *prefered_rounds)
+static /*@observer@*/void SHA_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds)
{
- static char rounds_prefix[18]; /* Max size: rounds=999999999$ */
- long 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);
long max_rounds = getdef_long ("SHA_CRYPT_MAX_ROUNDS", -1);
if ((-1 == min_rounds) && (-1 == max_rounds)) {
- return "";
+ rounds = SHA_ROUNDS_DEFAULT;
}
if (-1 == min_rounds) {
@@ -156,196 +194,142 @@ static /*@observer@*/const char *SHA_salt_rounds (/*@null@*/int *prefered_rounds
max_rounds = min_rounds;
}
- rounds = shadow_random (min_rounds, max_rounds);
+ rounds = (unsigned long) shadow_random (min_rounds, max_rounds);
} else if (0 == *prefered_rounds) {
- return "";
+ rounds = SHA_ROUNDS_DEFAULT;
} else {
- rounds = *prefered_rounds;
+ rounds = (unsigned long) *prefered_rounds;
}
/* Sanity checks. The libc should also check this, but this
* protects against a rounds_prefix overflow. */
- if (rounds < ROUNDS_MIN) {
- rounds = ROUNDS_MIN;
+ if (rounds < SHA_ROUNDS_MIN) {
+ rounds = SHA_ROUNDS_MIN;
+ }
+
+ if (rounds > SHA_ROUNDS_MAX) {
+ rounds = SHA_ROUNDS_MAX;
}
- if (rounds > ROUNDS_MAX) {
- rounds = ROUNDS_MAX;
+ /* Nothing to do here if SHA_ROUNDS_DEFAULT is used. */
+ if (rounds == SHA_ROUNDS_DEFAULT) {
+ return;
}
- (void) snprintf (rounds_prefix, sizeof rounds_prefix,
- "rounds=%ld$", rounds);
+ /* Check if the result buffer is long enough. */
+ assert (GENSALT_SETTING_SIZE > buf_begin + 17);
- return rounds_prefix;
+ (void) snprintf (buf + buf_begin, 18, "rounds=%lu$", rounds);
}
#endif /* USE_SHA_CRYPT */
#ifdef USE_BCRYPT
-/* Default number of rounds if not explicitly specified. */
-#define B_ROUNDS_DEFAULT 13
-/* Minimum number of rounds. */
-#define B_ROUNDS_MIN 4
-/* Maximum number of rounds. */
-#define B_ROUNDS_MAX 31
/*
- * Return a salt prefix specifying the rounds number for the BCRYPT method.
+ * Fill a salt prefix specifying the rounds number for the BCRYPT method
+ * to a buffer.
*/
-static /*@observer@*/const char *BCRYPT_salt_rounds (/*@null@*/int *prefered_rounds)
+static /*@observer@*/void BCRYPT_salt_rounds_to_buf (char *buf, /*@null@*/int *prefered_rounds)
{
- static char rounds_prefix[4]; /* Max size: 31$ */
- long rounds;
+ unsigned long rounds;
+ const size_t buf_begin = strlen (buf);
if (NULL == prefered_rounds) {
long min_rounds = getdef_long ("BCRYPT_MIN_ROUNDS", -1);
long max_rounds = getdef_long ("BCRYPT_MAX_ROUNDS", -1);
- if (((-1 == min_rounds) && (-1 == max_rounds)) || (0 == *prefered_rounds)) {
+ if ((-1 == min_rounds) && (-1 == max_rounds)) {
rounds = B_ROUNDS_DEFAULT;
- }
- else {
+ } else {
if (-1 == min_rounds) {
min_rounds = max_rounds;
}
-
+
if (-1 == max_rounds) {
max_rounds = min_rounds;
}
-
+
if (min_rounds > max_rounds) {
max_rounds = min_rounds;
}
-
- rounds = shadow_random (min_rounds, max_rounds);
+
+ rounds = (unsigned long) shadow_random (min_rounds, max_rounds);
}
+ } else if (0 == *prefered_rounds) {
+ rounds = B_ROUNDS_DEFAULT;
} else {
- rounds = *prefered_rounds;
+ rounds = (unsigned long) *prefered_rounds;
}
- /*
- * Sanity checks.
- * Use 19 as an upper bound for now,
- * because musl doesn't allow rounds >= 20.
- */
+ /* Sanity checks. */
if (rounds < B_ROUNDS_MIN) {
rounds = B_ROUNDS_MIN;
}
+ /*
+ * Use 19 as an upper bound for now,
+ * because musl doesn't allow rounds >= 20.
+ */
if (rounds > 19) {
/* rounds = B_ROUNDS_MAX; */
rounds = 19;
}
- (void) snprintf (rounds_prefix, sizeof rounds_prefix,
- "%2.2ld$", rounds);
-
- return rounds_prefix;
-}
-
-#define BCRYPT_SALT_SIZE 22
-/*
- * Generate a 22 character salt string for bcrypt.
- */
-static /*@observer@*/const char *gensalt_bcrypt (void)
-{
- static char salt[32];
-
- salt[0] = '\0';
+ /* Check if the result buffer is long enough. */
+ assert (GENSALT_SETTING_SIZE > buf_begin + 3);
- seedRNG ();
- strcat (salt, l64a (random()));
- do {
- strcat (salt, l64a (random()));
- } while (strlen (salt) < BCRYPT_SALT_SIZE);
-
- salt[BCRYPT_SALT_SIZE] = '\0';
-
- return salt;
+ (void) snprintf (buf + buf_begin, 4, "%2.2lu$", rounds);
}
#endif /* USE_BCRYPT */
#ifdef USE_YESCRYPT
-/* Default cost if not explicitly specified. */
-#define Y_COST_DEFAULT 5
-/* Minimum cost. */
-#define Y_COST_MIN 1
-/* Maximum cost. */
-#define Y_COST_MAX 11
/*
- * Return a salt prefix specifying the cost for the YESCRYPT method.
+ * Fill a salt prefix specifying the cost for the YESCRYPT method
+ * to a buffer.
*/
-static /*@observer@*/const char *YESCRYPT_salt_cost (/*@null@*/int *prefered_cost)
+static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, /*@null@*/int *prefered_cost)
{
- static char cost_prefix[5];
- long cost;
+ unsigned long cost;
+ const size_t buf_begin = strlen (buf);
if (NULL == prefered_cost) {
cost = getdef_num ("YESCRYPT_COST_FACTOR", Y_COST_DEFAULT);
+ } else if (0 == *prefered_cost) {
+ cost = Y_COST_DEFAULT;
} else {
- cost = *prefered_cost;
+ cost = (unsigned long) *prefered_cost;
}
+ /* Sanity checks. */
if (cost < Y_COST_MIN) {
cost = Y_COST_MIN;
}
+
if (cost > Y_COST_MAX) {
cost = Y_COST_MAX;
}
- cost_prefix[0] = 'j';
+ /* Check if the result buffer is long enough. */
+ assert (GENSALT_SETTING_SIZE > buf_begin + 3);
+
+ buf[buf_begin + 0] = 'j';
if (cost < 3) {
- cost_prefix[1] = 0x36 + cost;
+ buf[buf_begin + 1] = 0x36 + cost;
} else if (cost < 6) {
- cost_prefix[1] = 0x34 + cost;
+ buf[buf_begin + 1] = 0x34 + cost;
} else {
- cost_prefix[1] = 0x3b + cost;
+ buf[buf_begin + 1] = 0x3b + cost;
}
- cost_prefix[2] = cost >= 3 ? 'T' : '5';
- cost_prefix[3] = '$';
- cost_prefix[4] = 0;
-
- return cost_prefix;
-}
-
-/*
- * Default number of base64 characters used for the salt.
- * 24 characters gives a 144 bits (18 bytes) salt. Unlike the more
- * traditional 128 bits (16 bytes) salt, this 144 bits salt is always
- * represented by the same number of base64 characters without padding
- * issue, even with a non-standard base64 encoding scheme.
- */
-#define YESCRYPT_SALT_SIZE 24
-/*
- * Generate a 22 character salt string for yescrypt.
- */
-static /*@observer@*/const char *gensalt_yescrypt (void)
-{
- static char salt[32];
-
- salt[0] = '\0';
-
- seedRNG ();
- strcat (salt, l64a (random()));
- do {
- strcat (salt, l64a (random()));
- } while (strlen (salt) < YESCRYPT_SALT_SIZE);
-
- salt[YESCRYPT_SALT_SIZE] = '\0';
-
- return salt;
+ buf[buf_begin + 2] = cost >= 3 ? 'T' : '5';
+ buf[buf_begin + 3] = '$';
+ buf[buf_begin + 4] = '\0';
}
#endif /* USE_YESCRYPT */
-/*
- * Generate salt of size salt_size.
- */
-#define MAX_SALT_SIZE 16
-#define MIN_SALT_SIZE 8
-
static /*@observer@*/const char *gensalt (size_t salt_size)
{
- static char salt[32];
+ static char salt[MAX_SALT_SIZE + 6];
- salt[0] = '\0';
+ memset (salt, '\0', MAX_SALT_SIZE + 6);
assert (salt_size >= MIN_SALT_SIZE &&
salt_size <= MAX_SALT_SIZE);
@@ -368,8 +352,9 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
* Other methods can be set with ENCRYPT_METHOD
*
* The method can be forced with the meth parameter.
- * If NULL, the method will be defined according to the MD5_CRYPT_ENAB and
- * ENCRYPT_METHOD login.defs variables.
+ * If NULL, the method will be defined according to the ENCRYPT_METHOD
+ * variable, and if not set according to the MD5_CRYPT_ENAB variable,
+ * which can both be set inside the login.defs file.
*
* If meth is specified, an additional parameter can be provided.
* * For the SHA256 and SHA512 method, this specifies the number of rounds
@@ -378,17 +363,11 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
*/
/*@observer@*/const char *crypt_make_salt (/*@null@*//*@observer@*/const char *meth, /*@null@*/void *arg)
{
- /* Max result size for the SHA methods:
- * +3 $5$
- * +17 rounds=999999999$
- * +16 salt
- * +1 \0
- */
- static char result[40];
- size_t salt_len = 8;
+ static char result[GENSALT_SETTING_SIZE];
+ size_t salt_len = MAX_SALT_SIZE;
const char *method;
- result[0] = '\0';
+ memset (result, '\0', GENSALT_SETTING_SIZE);
if (NULL != meth)
method = meth;
@@ -401,61 +380,44 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
if (0 == strcmp (method, "MD5")) {
MAGNUM(result, '1');
+ salt_len = MD5_CRYPT_SALT_SIZE;
#ifdef USE_BCRYPT
} else if (0 == strcmp (method, "BCRYPT")) {
BCRYPTMAGNUM(result);
- strcat(result, BCRYPT_salt_rounds((int *)arg));
+ salt_len = BCRYPT_SALT_SIZE;
+ BCRYPT_salt_rounds_to_buf (result, (int *) arg);
#endif /* USE_BCRYPT */
#ifdef USE_YESCRYPT
} else if (0 == strcmp (method, "YESCRYPT")) {
MAGNUM(result, 'y');
- strcat(result, YESCRYPT_salt_cost((int *)arg));
+ salt_len = YESCRYPT_SALT_SIZE;
+ YESCRYPT_salt_cost_to_buf (result, (int *) arg);
#endif /* USE_YESCRYPT */
#ifdef USE_SHA_CRYPT
} else if (0 == strcmp (method, "SHA256")) {
MAGNUM(result, '5');
- strcat(result, SHA_salt_rounds((int *)arg));
- salt_len = (size_t) shadow_random (8, 16);
+ salt_len = SHA_CRYPT_SALT_SIZE;
+ SHA_salt_rounds_to_buf (result, (int *) arg);
} else if (0 == strcmp (method, "SHA512")) {
MAGNUM(result, '6');
- strcat(result, SHA_salt_rounds((int *)arg));
- salt_len = (size_t) shadow_random (8, 16);
+ salt_len = SHA_CRYPT_SALT_SIZE;
+ SHA_salt_rounds_to_buf (result, (int *) arg);
#endif /* USE_SHA_CRYPT */
} else if (0 != strcmp (method, "DES")) {
fprintf (shadow_logfd,
_("Invalid ENCRYPT_METHOD value: '%s'.\n"
"Defaulting to DES.\n"),
method);
- result[0] = '\0';
+ salt_len = MAX_SALT_SIZE;
+ memset (result, '\0', GENSALT_SETTING_SIZE);
}
- /*
- * Concatenate a pseudo random salt.
- */
- assert (sizeof (result) > strlen (result) + salt_len);
-#ifdef USE_BCRYPT
- if (0 == strcmp (method, "BCRYPT")) {
- strncat (result, gensalt_bcrypt (),
- sizeof (result) - strlen (result) - 1);
- return result;
- } else {
-#endif /* USE_BCRYPT */
-#ifdef USE_YESCRYPT
- if (0 == strcmp (method, "YESCRYPT")) {
- strncat (result, gensalt_yescrypt (),
- sizeof (result) - strlen (result) - 1);
- return result;
- } else {
-#endif /* USE_YESCRYPT */
- strncat (result, gensalt (salt_len),
- sizeof (result) - strlen (result) - 1);
-#ifdef USE_YESCRYPT
- }
-#endif /* USE_YESCRYPT */
-#ifdef USE_BCRYPT
- }
-#endif /* USE_BCRYPT */
+ /* Check if the result buffer is long enough. */
+ assert (GENSALT_SETTING_SIZE > strlen (result) + salt_len);
+
+ /* Concatenate a pseudo random salt. */
+ strncat (result, gensalt (salt_len),
+ GENSALT_SETTING_SIZE - strlen (result) - 1);
return result;
}
-

4
shadow-utils.spec
View File

@ -108,6 +108,8 @@ Patch59: shadow-4.8.1-fix_YESCRYPT_salt_cost_param_type.patch
Patch60: shadow-4.8.1-covscan_fixes.patch
# https://github.com/shadow-maint/shadow/commit/738d92a4bd99a2038aa5f97b2fc85daa7011e403
Patch61: shadow-4.8.1-fix_bcrypt_prefix.patch
# https://github.com/shadow-maint/shadow/commit/14b108728a5d55c3d478a170c39f0e2ffd4de1b0
Patch62: shadow-4.8.1-salt_c_sanitize_code.patch
License: BSD and GPLv2+
BuildRequires: make
@ -194,6 +196,7 @@ Development files for shadow-utils-subid.
%patch59 -p1 -b .YESCRYPT_salt_cost_param_type
%patch60 -p1 -b .covscan_fixes
%patch61 -p1 -b .bcrypt_prefix
%patch62 -p1 -b .sanitize_code
iconv -f ISO88591 -t utf-8 doc/HOWTO > doc/HOWTO.utf8
cp -f doc/HOWTO.utf8 doc/HOWTO
@ -365,6 +368,7 @@ rm -f $RPM_BUILD_ROOT/%{_libdir}/libsubid.la
%changelog
* Mon Jun 28 2021 Björn Esser <besser82@fedoraproject.org> - 2:4.8.1-14
- Add a patch to fix the used prefix for the bcrypt hash method
- Add a patch to cleanup the code in libmisc/salt.c
* Mon Jun 28 2021 Iker Pedrosa <ipedrosa@redhat.com> - 2:4.8.1-13
- Covscan fixes