bind9/lib/dns/dst_parse.c
Ondřej Surý 718893ece4
Replace isc_fsaccess API with more secure file creation
The isc_fsaccess API was created to hide the implementation details
between POSIX and Windows APIs.  As we are not supporting the Windows
APIs anymore, it's better to drop this API used in the DST part.

Moreover, the isc_fsaccess was setting the permissions in an insecure
manner - it operated on the filename, and not on the file descriptor
which can lead to all kind of attacks if unpriviledged user has read (or
even worse write) access to key directory.

Replace the code that operates on the private keys with code that uses
mkstemp(), fchmod() and atomic rename() at the end, so at no time the
private key files have insecure permissions.

(cherry picked from commit 263d232c79)
2023-03-31 16:47:15 +02:00

798 lines
18 KiB
C

/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* SPDX-License-Identifier: MPL-2.0 AND ISC
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, you can obtain one at https://mozilla.org/MPL/2.0/.
*
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
*/
/*
* Copyright (C) Network Associates, Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC AND NETWORK ASSOCIATES DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE
* FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
* IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "dst_parse.h"
#include <inttypes.h>
#include <stdbool.h>
#include <unistd.h>
#include <isc/base64.h>
#include <isc/dir.h>
#include <isc/file.h>
#include <isc/lex.h>
#include <isc/mem.h>
#include <isc/print.h>
#include <isc/stdtime.h>
#include <isc/string.h>
#include <isc/util.h>
#include <dns/log.h>
#include <dns/time.h>
#include "dst_internal.h"
#include "isc/result.h"
#define DST_AS_STR(t) ((t).value.as_textregion.base)
#define PRIVATE_KEY_STR "Private-key-format:"
#define ALGORITHM_STR "Algorithm:"
#define TIMING_NTAGS (DST_MAX_TIMES + 1)
static const char *timetags[TIMING_NTAGS] = {
"Created:", "Publish:", "Activate:", "Revoke:",
"Inactive:", "Delete:", "DSPublish:", "SyncPublish:",
"SyncDelete:", NULL, NULL, NULL,
NULL
};
#define NUMERIC_NTAGS (DST_MAX_NUMERIC + 1)
static const char *numerictags[NUMERIC_NTAGS] = {
"Predecessor:", "Successor:", "MaxTTL:", "RollPeriod:", NULL, NULL, NULL
};
struct parse_map {
const int value;
const char *tag;
};
static struct parse_map map[] = { { TAG_RSA_MODULUS, "Modulus:" },
{ TAG_RSA_PUBLICEXPONENT, "PublicExponent:" },
{ TAG_RSA_PRIVATEEXPONENT, "PrivateExponent"
":" },
{ TAG_RSA_PRIME1, "Prime1:" },
{ TAG_RSA_PRIME2, "Prime2:" },
{ TAG_RSA_EXPONENT1, "Exponent1:" },
{ TAG_RSA_EXPONENT2, "Exponent2:" },
{ TAG_RSA_COEFFICIENT, "Coefficient:" },
{ TAG_RSA_ENGINE, "Engine:" },
{ TAG_RSA_LABEL, "Label:" },
{ TAG_DH_PRIME, "Prime(p):" },
{ TAG_DH_GENERATOR, "Generator(g):" },
{ TAG_DH_PRIVATE, "Private_value(x):" },
{ TAG_DH_PUBLIC, "Public_value(y):" },
{ TAG_ECDSA_PRIVATEKEY, "PrivateKey:" },
{ TAG_ECDSA_ENGINE, "Engine:" },
{ TAG_ECDSA_LABEL, "Label:" },
{ TAG_EDDSA_PRIVATEKEY, "PrivateKey:" },
{ TAG_EDDSA_ENGINE, "Engine:" },
{ TAG_EDDSA_LABEL, "Label:" },
{ TAG_HMACMD5_KEY, "Key:" },
{ TAG_HMACMD5_BITS, "Bits:" },
{ TAG_HMACSHA1_KEY, "Key:" },
{ TAG_HMACSHA1_BITS, "Bits:" },
{ TAG_HMACSHA224_KEY, "Key:" },
{ TAG_HMACSHA224_BITS, "Bits:" },
{ TAG_HMACSHA256_KEY, "Key:" },
{ TAG_HMACSHA256_BITS, "Bits:" },
{ TAG_HMACSHA384_KEY, "Key:" },
{ TAG_HMACSHA384_BITS, "Bits:" },
{ TAG_HMACSHA512_KEY, "Key:" },
{ TAG_HMACSHA512_BITS, "Bits:" },
{ 0, NULL } };
static int
find_value(const char *s, const unsigned int alg) {
int i;
for (i = 0; map[i].tag != NULL; i++) {
if (strcasecmp(s, map[i].tag) == 0 &&
(TAG_ALG(map[i].value) == alg))
{
return (map[i].value);
}
}
return (-1);
}
static const char *
find_tag(const int value) {
int i;
for (i = 0;; i++) {
if (map[i].tag == NULL) {
return (NULL);
} else if (value == map[i].value) {
return (map[i].tag);
}
}
}
static int
find_metadata(const char *s, const char *tags[], int ntags) {
int i;
for (i = 0; i < ntags; i++) {
if (tags[i] != NULL && strcasecmp(s, tags[i]) == 0) {
return (i);
}
}
return (-1);
}
static int
find_timedata(const char *s) {
return (find_metadata(s, timetags, TIMING_NTAGS));
}
static int
find_numericdata(const char *s) {
return (find_metadata(s, numerictags, NUMERIC_NTAGS));
}
static int
check_rsa(const dst_private_t *priv, bool external) {
int i, j;
bool have[RSA_NTAGS];
bool ok;
unsigned int mask;
if (external) {
return ((priv->nelements == 0) ? 0 : -1);
}
for (i = 0; i < RSA_NTAGS; i++) {
have[i] = false;
}
for (j = 0; j < priv->nelements; j++) {
for (i = 0; i < RSA_NTAGS; i++) {
if (priv->elements[j].tag == TAG(DST_ALG_RSA, i)) {
break;
}
}
if (i == RSA_NTAGS) {
return (-1);
}
have[i] = true;
}
mask = (1ULL << TAG_SHIFT) - 1;
if (have[TAG_RSA_ENGINE & mask]) {
ok = have[TAG_RSA_MODULUS & mask] &&
have[TAG_RSA_PUBLICEXPONENT & mask] &&
have[TAG_RSA_LABEL & mask];
} else {
ok = have[TAG_RSA_MODULUS & mask] &&
have[TAG_RSA_PUBLICEXPONENT & mask] &&
have[TAG_RSA_PRIVATEEXPONENT & mask] &&
have[TAG_RSA_PRIME1 & mask] &&
have[TAG_RSA_PRIME2 & mask] &&
have[TAG_RSA_EXPONENT1 & mask] &&
have[TAG_RSA_EXPONENT2 & mask] &&
have[TAG_RSA_COEFFICIENT & mask];
}
return (ok ? 0 : -1);
}
static int
check_dh(const dst_private_t *priv) {
int i, j;
if (priv->nelements != DH_NTAGS) {
return (-1);
}
for (i = 0; i < DH_NTAGS; i++) {
for (j = 0; j < priv->nelements; j++) {
if (priv->elements[j].tag == TAG(DST_ALG_DH, i)) {
break;
}
}
if (j == priv->nelements) {
return (-1);
}
}
return (0);
}
static int
check_ecdsa(const dst_private_t *priv, bool external) {
int i, j;
bool have[ECDSA_NTAGS];
bool ok;
unsigned int mask;
if (external) {
return ((priv->nelements == 0) ? 0 : -1);
}
for (i = 0; i < ECDSA_NTAGS; i++) {
have[i] = false;
}
for (j = 0; j < priv->nelements; j++) {
for (i = 0; i < ECDSA_NTAGS; i++) {
if (priv->elements[j].tag == TAG(DST_ALG_ECDSA256, i)) {
break;
}
}
if (i == ECDSA_NTAGS) {
return (-1);
}
have[i] = true;
}
mask = (1ULL << TAG_SHIFT) - 1;
if (have[TAG_ECDSA_ENGINE & mask]) {
ok = have[TAG_ECDSA_LABEL & mask];
} else {
ok = have[TAG_ECDSA_PRIVATEKEY & mask];
}
return (ok ? 0 : -1);
}
static int
check_eddsa(const dst_private_t *priv, bool external) {
int i, j;
bool have[EDDSA_NTAGS];
bool ok;
unsigned int mask;
if (external) {
return ((priv->nelements == 0) ? 0 : -1);
}
for (i = 0; i < EDDSA_NTAGS; i++) {
have[i] = false;
}
for (j = 0; j < priv->nelements; j++) {
for (i = 0; i < EDDSA_NTAGS; i++) {
if (priv->elements[j].tag == TAG(DST_ALG_ED25519, i)) {
break;
}
}
if (i == EDDSA_NTAGS) {
return (-1);
}
have[i] = true;
}
mask = (1ULL << TAG_SHIFT) - 1;
if (have[TAG_EDDSA_ENGINE & mask]) {
ok = have[TAG_EDDSA_LABEL & mask];
} else {
ok = have[TAG_EDDSA_PRIVATEKEY & mask];
}
return (ok ? 0 : -1);
}
static int
check_hmac_md5(const dst_private_t *priv, bool old) {
int i, j;
if (priv->nelements != HMACMD5_NTAGS) {
/*
* If this is a good old format and we are accepting
* the old format return success.
*/
if (old && priv->nelements == OLD_HMACMD5_NTAGS &&
priv->elements[0].tag == TAG_HMACMD5_KEY)
{
return (0);
}
return (-1);
}
/*
* We must be new format at this point.
*/
for (i = 0; i < HMACMD5_NTAGS; i++) {
for (j = 0; j < priv->nelements; j++) {
if (priv->elements[j].tag == TAG(DST_ALG_HMACMD5, i)) {
break;
}
}
if (j == priv->nelements) {
return (-1);
}
}
return (0);
}
static int
check_hmac_sha(const dst_private_t *priv, unsigned int ntags,
unsigned int alg) {
unsigned int i, j;
if (priv->nelements != ntags) {
return (-1);
}
for (i = 0; i < ntags; i++) {
for (j = 0; j < priv->nelements; j++) {
if (priv->elements[j].tag == TAG(alg, i)) {
break;
}
}
if (j == priv->nelements) {
return (-1);
}
}
return (0);
}
static int
check_data(const dst_private_t *priv, const unsigned int alg, bool old,
bool external) {
/* XXXVIX this switch statement is too sparse to gen a jump table. */
switch (alg) {
case DST_ALG_RSA:
case DST_ALG_RSASHA1:
case DST_ALG_NSEC3RSASHA1:
case DST_ALG_RSASHA256:
case DST_ALG_RSASHA512:
return (check_rsa(priv, external));
case DST_ALG_DH:
return (check_dh(priv));
case DST_ALG_ECDSA256:
case DST_ALG_ECDSA384:
return (check_ecdsa(priv, external));
case DST_ALG_ED25519:
case DST_ALG_ED448:
return (check_eddsa(priv, external));
case DST_ALG_HMACMD5:
return (check_hmac_md5(priv, old));
case DST_ALG_HMACSHA1:
return (check_hmac_sha(priv, HMACSHA1_NTAGS, alg));
case DST_ALG_HMACSHA224:
return (check_hmac_sha(priv, HMACSHA224_NTAGS, alg));
case DST_ALG_HMACSHA256:
return (check_hmac_sha(priv, HMACSHA256_NTAGS, alg));
case DST_ALG_HMACSHA384:
return (check_hmac_sha(priv, HMACSHA384_NTAGS, alg));
case DST_ALG_HMACSHA512:
return (check_hmac_sha(priv, HMACSHA512_NTAGS, alg));
default:
return (DST_R_UNSUPPORTEDALG);
}
}
void
dst__privstruct_free(dst_private_t *priv, isc_mem_t *mctx) {
int i;
if (priv == NULL) {
return;
}
for (i = 0; i < priv->nelements; i++) {
if (priv->elements[i].data == NULL) {
continue;
}
memset(priv->elements[i].data, 0, MAXFIELDSIZE);
isc_mem_put(mctx, priv->elements[i].data, MAXFIELDSIZE);
}
priv->nelements = 0;
}
isc_result_t
dst__privstruct_parse(dst_key_t *key, unsigned int alg, isc_lex_t *lex,
isc_mem_t *mctx, dst_private_t *priv) {
int n = 0, major, minor, check;
isc_buffer_t b;
isc_token_t token;
unsigned char *data = NULL;
unsigned int opt = ISC_LEXOPT_EOL;
isc_stdtime_t when;
isc_result_t ret;
bool external = false;
REQUIRE(priv != NULL);
priv->nelements = 0;
memset(priv->elements, 0, sizeof(priv->elements));
#define NEXTTOKEN(lex, opt, token) \
do { \
ret = isc_lex_gettoken(lex, opt, token); \
if (ret != ISC_R_SUCCESS) \
goto fail; \
} while (0)
#define READLINE(lex, opt, token) \
do { \
ret = isc_lex_gettoken(lex, opt, token); \
if (ret == ISC_R_EOF) \
break; \
else if (ret != ISC_R_SUCCESS) \
goto fail; \
} while ((*token).type != isc_tokentype_eol)
/*
* Read the description line.
*/
NEXTTOKEN(lex, opt, &token);
if (token.type != isc_tokentype_string ||
strcmp(DST_AS_STR(token), PRIVATE_KEY_STR) != 0)
{
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
NEXTTOKEN(lex, opt, &token);
if (token.type != isc_tokentype_string || (DST_AS_STR(token))[0] != 'v')
{
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
if (sscanf(DST_AS_STR(token), "v%d.%d", &major, &minor) != 2) {
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
if (major > DST_MAJOR_VERSION) {
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
/*
* Store the private key format version number
*/
dst_key_setprivateformat(key, major, minor);
READLINE(lex, opt, &token);
/*
* Read the algorithm line.
*/
NEXTTOKEN(lex, opt, &token);
if (token.type != isc_tokentype_string ||
strcmp(DST_AS_STR(token), ALGORITHM_STR) != 0)
{
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
NEXTTOKEN(lex, opt | ISC_LEXOPT_NUMBER, &token);
if (token.type != isc_tokentype_number ||
token.value.as_ulong != (unsigned long)dst_key_alg(key))
{
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
READLINE(lex, opt, &token);
/*
* Read the key data.
*/
for (n = 0; n < MAXFIELDS; n++) {
int tag;
isc_region_t r;
do {
ret = isc_lex_gettoken(lex, opt, &token);
if (ret == ISC_R_EOF) {
goto done;
}
if (ret != ISC_R_SUCCESS) {
goto fail;
}
} while (token.type == isc_tokentype_eol);
if (token.type != isc_tokentype_string) {
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
if (strcmp(DST_AS_STR(token), "External:") == 0) {
external = true;
goto next;
}
/* Numeric metadata */
tag = find_numericdata(DST_AS_STR(token));
if (tag >= 0) {
INSIST(tag < NUMERIC_NTAGS);
NEXTTOKEN(lex, opt | ISC_LEXOPT_NUMBER, &token);
if (token.type != isc_tokentype_number) {
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
dst_key_setnum(key, tag, token.value.as_ulong);
goto next;
}
/* Timing metadata */
tag = find_timedata(DST_AS_STR(token));
if (tag >= 0) {
INSIST(tag < TIMING_NTAGS);
NEXTTOKEN(lex, opt, &token);
if (token.type != isc_tokentype_string) {
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
ret = dns_time32_fromtext(DST_AS_STR(token), &when);
if (ret != ISC_R_SUCCESS) {
goto fail;
}
dst_key_settime(key, tag, when);
goto next;
}
/* Key data */
tag = find_value(DST_AS_STR(token), alg);
if (tag < 0 && minor > DST_MINOR_VERSION) {
goto next;
} else if (tag < 0) {
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
priv->elements[n].tag = tag;
data = isc_mem_get(mctx, MAXFIELDSIZE);
isc_buffer_init(&b, data, MAXFIELDSIZE);
ret = isc_base64_tobuffer(lex, &b, -1);
if (ret != ISC_R_SUCCESS) {
goto fail;
}
isc_buffer_usedregion(&b, &r);
priv->elements[n].length = r.length;
priv->elements[n].data = r.base;
priv->nelements++;
next:
READLINE(lex, opt, &token);
data = NULL;
}
done:
if (external && priv->nelements != 0) {
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
}
check = check_data(priv, alg, true, external);
if (check < 0) {
ret = DST_R_INVALIDPRIVATEKEY;
goto fail;
} else if (check != ISC_R_SUCCESS) {
ret = check;
goto fail;
}
key->external = external;
return (ISC_R_SUCCESS);
fail:
dst__privstruct_free(priv, mctx);
if (data != NULL) {
isc_mem_put(mctx, data, MAXFIELDSIZE);
}
return (ret);
}
isc_result_t
dst__privstruct_writefile(const dst_key_t *key, const dst_private_t *priv,
const char *directory) {
FILE *fp;
isc_result_t result;
char filename[NAME_MAX];
char tmpname[NAME_MAX];
char buffer[MAXFIELDSIZE * 2];
isc_stdtime_t when;
uint32_t value;
isc_buffer_t b;
isc_buffer_t fileb;
isc_buffer_t tmpb;
isc_region_t r;
int major, minor;
mode_t mode;
int i, ret;
REQUIRE(priv != NULL);
ret = check_data(priv, dst_key_alg(key), false, key->external);
if (ret < 0) {
return (DST_R_INVALIDPRIVATEKEY);
} else if (ret != ISC_R_SUCCESS) {
return (ret);
}
isc_buffer_init(&fileb, filename, sizeof(filename));
result = dst_key_buildfilename(key, DST_TYPE_PRIVATE, directory,
&fileb);
if (result != ISC_R_SUCCESS) {
return (result);
}
result = isc_file_mode(filename, &mode);
if (result == ISC_R_SUCCESS && mode != (S_IRUSR | S_IWUSR)) {
/* File exists; warn that we are changing its permissions */
int level;
level = ISC_LOG_WARNING;
isc_log_write(dns_lctx, DNS_LOGCATEGORY_GENERAL,
DNS_LOGMODULE_DNSSEC, level,
"Permissions on the file %s "
"have changed from 0%o to 0600 as "
"a result of this operation.",
filename, (unsigned int)mode);
}
isc_buffer_init(&tmpb, tmpname, sizeof(tmpname));
result = dst_key_buildfilename(key, DST_TYPE_TEMPLATE, directory,
&tmpb);
if (result != ISC_R_SUCCESS) {
return (result);
}
fp = dst_key_open(tmpname, S_IRUSR | S_IWUSR);
if (fp == NULL) {
return (DST_R_WRITEERROR);
}
dst_key_getprivateformat(key, &major, &minor);
if (major == 0 && minor == 0) {
major = DST_MAJOR_VERSION;
minor = DST_MINOR_VERSION;
}
/* XXXDCL return value should be checked for full filesystem */
fprintf(fp, "%s v%d.%d\n", PRIVATE_KEY_STR, major, minor);
fprintf(fp, "%s %u ", ALGORITHM_STR, dst_key_alg(key));
/* XXXVIX this switch statement is too sparse to gen a jump table. */
switch (dst_key_alg(key)) {
case DST_ALG_DH:
fprintf(fp, "(DH)\n");
break;
case DST_ALG_RSASHA1:
fprintf(fp, "(RSASHA1)\n");
break;
case DST_ALG_NSEC3RSASHA1:
fprintf(fp, "(NSEC3RSASHA1)\n");
break;
case DST_ALG_RSASHA256:
fprintf(fp, "(RSASHA256)\n");
break;
case DST_ALG_RSASHA512:
fprintf(fp, "(RSASHA512)\n");
break;
case DST_ALG_ECDSA256:
fprintf(fp, "(ECDSAP256SHA256)\n");
break;
case DST_ALG_ECDSA384:
fprintf(fp, "(ECDSAP384SHA384)\n");
break;
case DST_ALG_ED25519:
fprintf(fp, "(ED25519)\n");
break;
case DST_ALG_ED448:
fprintf(fp, "(ED448)\n");
break;
case DST_ALG_HMACMD5:
fprintf(fp, "(HMAC_MD5)\n");
break;
case DST_ALG_HMACSHA1:
fprintf(fp, "(HMAC_SHA1)\n");
break;
case DST_ALG_HMACSHA224:
fprintf(fp, "(HMAC_SHA224)\n");
break;
case DST_ALG_HMACSHA256:
fprintf(fp, "(HMAC_SHA256)\n");
break;
case DST_ALG_HMACSHA384:
fprintf(fp, "(HMAC_SHA384)\n");
break;
case DST_ALG_HMACSHA512:
fprintf(fp, "(HMAC_SHA512)\n");
break;
default:
fprintf(fp, "(?)\n");
break;
}
for (i = 0; i < priv->nelements; i++) {
const char *s;
s = find_tag(priv->elements[i].tag);
r.base = priv->elements[i].data;
r.length = priv->elements[i].length;
isc_buffer_init(&b, buffer, sizeof(buffer));
result = isc_base64_totext(&r, sizeof(buffer), "", &b);
if (result != ISC_R_SUCCESS) {
return (dst_key_cleanup(tmpname, fp));
}
isc_buffer_usedregion(&b, &r);
fprintf(fp, "%s %.*s\n", s, (int)r.length, r.base);
}
if (key->external) {
fprintf(fp, "External:\n");
}
/* Add the metadata tags */
if (major > 1 || (major == 1 && minor >= 3)) {
for (i = 0; i < NUMERIC_NTAGS; i++) {
result = dst_key_getnum(key, i, &value);
if (result != ISC_R_SUCCESS) {
continue;
}
if (numerictags[i] != NULL) {
fprintf(fp, "%s %u\n", numerictags[i], value);
}
}
for (i = 0; i < TIMING_NTAGS; i++) {
result = dst_key_gettime(key, i, &when);
if (result != ISC_R_SUCCESS) {
continue;
}
isc_buffer_init(&b, buffer, sizeof(buffer));
result = dns_time32_totext(when, &b);
if (result != ISC_R_SUCCESS) {
return (dst_key_cleanup(tmpname, fp));
}
isc_buffer_usedregion(&b, &r);
if (timetags[i] != NULL) {
fprintf(fp, "%s %.*s\n", timetags[i],
(int)r.length, r.base);
}
}
}
result = dst_key_close(tmpname, fp, filename);
return (result);
}
/*! \file */