denyhosts/clamav/libclamav/dsig.c

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/*
* Copyright (C) 2013-2022 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2007-2013 Sourcefire, Inc.
*
* Authors: Tomasz Kojm
*
* Acknowledgements: The idea of number encoding comes from yyyRSA by
* Erik Thiele.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include "clamav.h"
#include "others.h"
#include "dsig.h"
#include "str.h"
#include "bignum.h"
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#ifndef _WIN32
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#else
#include "w32_stat.h"
#endif
#ifdef HAVE_TERMIOS_H
#include <termios.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
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#define CLI_NSTR "118640995551645342603070001658453189751527774412027743746599405743243142607464144767361060640655844749760788890022283424922762488917565551002467771109669598189410434699034532232228621591089508178591428456220796841621637175567590476666928698770143328137383952820383197532047771780196576957695822641224262693037"
#define CLI_ESTR "100001027"
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#define MP_GET(a) ((a)->used > 0 ? (a)->dp[0] : 0)
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static char cli_ndecode(unsigned char value)
{
unsigned int i;
char ncodec[] = {
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
'y', 'z',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
'Y', 'Z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'+', '/'};
for (i = 0; i < 64; i++)
if (ncodec[i] == value)
return i;
cli_errmsg("cli_ndecode: value out of range\n");
return -1;
}
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static unsigned char *cli_decodesig(const char *sig, unsigned int plen, fp_int e, fp_int n)
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{
int i, slen = strlen(sig), dec;
unsigned char *plain;
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fp_int r, p, c;
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fp_init(&r);
fp_init(&c);
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for (i = 0; i < slen; i++) {
if ((dec = cli_ndecode(sig[i])) < 0) {
return NULL;
}
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fp_set(&r, dec);
fp_mul_2d(&r, 6 * i, &r);
fp_add(&r, &c, &c);
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}
plain = (unsigned char *)cli_calloc(plen + 1, sizeof(unsigned char));
if (!plain) {
cli_errmsg("cli_decodesig: Can't allocate memory for 'plain'\n");
return NULL;
}
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fp_init(&p);
fp_exptmod(&c, &e, &n, &p); /* plain = cipher^e mod n */
fp_set(&c, 256);
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for (i = plen - 1; i >= 0; i--) { /* reverse */
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fp_div(&p, &c, &p, &r);
plain[i] = MP_GET(&r);
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}
return plain;
}
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char *cli_getdsig(const char *host, const char *user, const unsigned char *data, unsigned int datalen, unsigned short mode)
{
char buff[512], cmd[128], pass[31], *pt;
struct sockaddr_in server;
int sockd, bread, len;
#ifdef HAVE_TERMIOS_H
struct termios old, new;
#endif
memset(&server, 0x00, sizeof(struct sockaddr_in));
if ((pt = getenv("SIGNDPASS"))) {
strncpy(pass, pt, sizeof(pass));
pass[sizeof(pass) - 1] = '\0';
} else {
cli_infomsg(NULL, "Password: ");
#ifdef HAVE_TERMIOS_H
if (tcgetattr(0, &old)) {
cli_errmsg("getdsig: tcgetattr() failed\n");
return NULL;
}
new = old;
new.c_lflag &= ~ECHO;
if (tcsetattr(0, TCSAFLUSH, &new)) {
cli_errmsg("getdsig: tcsetattr() failed\n");
return NULL;
}
#endif
if (scanf("%30s", pass) == EOF) {
cli_errmsg("getdsig: Can't get password\n");
#ifdef HAVE_TERMIOS_H
tcsetattr(0, TCSAFLUSH, &old);
#endif
return NULL;
}
#ifdef HAVE_TERMIOS_H
if (tcsetattr(0, TCSAFLUSH, &old)) {
cli_errmsg("getdsig: tcsetattr() failed\n");
memset(pass, 0, sizeof(pass));
return NULL;
}
#endif
cli_infomsg(NULL, "\n");
}
if ((sockd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("socket()");
cli_errmsg("getdsig: Can't create socket\n");
memset(pass, 0, sizeof(pass));
return NULL;
}
server.sin_family = AF_INET;
server.sin_addr.s_addr = inet_addr(host);
server.sin_port = htons(33101);
if (connect(sockd, (struct sockaddr *)&server, sizeof(struct sockaddr_in)) < 0) {
perror("connect()");
closesocket(sockd);
cli_errmsg("getdsig: Can't connect to ClamAV Signing Service at %s\n", host);
memset(pass, 0, sizeof(pass));
return NULL;
}
memset(cmd, 0, sizeof(cmd));
if (mode == 1)
snprintf(cmd, sizeof(cmd) - datalen, "ClamSign:%s:%s:", user, pass);
else if (mode == 2)
snprintf(cmd, sizeof(cmd) - datalen, "ClamSignPSS:%s:%s:", user, pass);
else
snprintf(cmd, sizeof(cmd) - datalen, "ClamSignPSS2:%s:%s:", user, pass);
len = strlen(cmd);
pt = cmd + len;
memcpy(pt, data, datalen);
len += datalen;
if (send(sockd, cmd, len, 0) < 0) {
cli_errmsg("getdsig: Can't write to socket\n");
closesocket(sockd);
memset(cmd, 0, sizeof(cmd));
memset(pass, 0, sizeof(pass));
return NULL;
}
memset(cmd, 0, sizeof(cmd));
memset(pass, 0, sizeof(pass));
memset(buff, 0, sizeof(buff));
if ((bread = recv(sockd, buff, sizeof(buff) - 1, 0)) > 0) {
buff[bread] = '\0';
if (!strstr(buff, "Signature:")) {
cli_errmsg("getdsig: Error generating digital signature\n");
cli_errmsg("getdsig: Answer from remote server: %s\n", buff);
closesocket(sockd);
return NULL;
} else {
cli_infomsg(NULL, "Signature received (length = %lu)\n", (unsigned long)strlen(buff) - 10);
}
} else {
cli_errmsg("getdsig: Communication error with remote server\n");
closesocket(sockd);
return NULL;
}
closesocket(sockd);
pt = buff;
pt += 10;
return strdup(pt);
}
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int cli_versig(const char *md5, const char *dsig)
{
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fp_int n, e;
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char *pt, *pt2;
if (strlen(md5) != 32 || !isalnum(md5[0])) {
/* someone is trying to fool us with empty/malformed MD5 ? */
cli_errmsg("SECURITY WARNING: MD5 basic test failure.\n");
return CL_EVERIFY;
}
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fp_init(&n);
fp_read_radix(&n, CLI_NSTR, 10);
fp_init(&e);
fp_read_radix(&e, CLI_ESTR, 10);
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if (!(pt = (char *)cli_decodesig(dsig, 16, e, n))) {
return CL_EVERIFY;
}
pt2 = cli_str2hex(pt, 16);
free(pt);
cli_dbgmsg("cli_versig: Decoded signature: %s\n", pt2);
if (strncmp(md5, pt2, 32)) {
cli_dbgmsg("cli_versig: Signature doesn't match.\n");
free(pt2);
return CL_EVERIFY;
}
free(pt2);
cli_dbgmsg("cli_versig: Digital signature is correct.\n");
return CL_SUCCESS;
}
#define HASH_LEN 32
#define SALT_LEN 32
#define PAD_LEN (2048 / 8)
#define BLK_LEN (PAD_LEN - HASH_LEN - 1)
int cli_versig2(const unsigned char *sha256, const char *dsig_str, const char *n_str, const char *e_str)
{
unsigned char *decoded, digest1[HASH_LEN], digest2[HASH_LEN], digest3[HASH_LEN], *salt;
unsigned char mask[BLK_LEN], data[BLK_LEN], final[8 + 2 * HASH_LEN], c[4];
unsigned int i, rounds;
void *ctx;
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fp_int n, e;
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fp_init(&e);
fp_read_radix(&e, e_str, 10);
fp_init(&n);
fp_read_radix(&n, n_str, 10);
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decoded = cli_decodesig(dsig_str, PAD_LEN, e, n);
if (!decoded)
return CL_EVERIFY;
if (decoded[PAD_LEN - 1] != 0xbc) {
free(decoded);
return CL_EVERIFY;
}
memcpy(mask, decoded, BLK_LEN);
memcpy(digest2, &decoded[BLK_LEN], HASH_LEN);
free(decoded);
c[0] = c[1] = 0;
rounds = (BLK_LEN + HASH_LEN - 1) / HASH_LEN;
for (i = 0; i < rounds; i++) {
c[2] = (unsigned char)(i / 256);
c[3] = (unsigned char)i;
ctx = cl_hash_init("sha256");
if (!(ctx))
return CL_EMEM;
cl_update_hash(ctx, digest2, HASH_LEN);
cl_update_hash(ctx, c, 4);
cl_finish_hash(ctx, digest3);
if (i + 1 == rounds)
memcpy(&data[i * 32], digest3, BLK_LEN - i * HASH_LEN);
else
memcpy(&data[i * 32], digest3, HASH_LEN);
}
for (i = 0; i < BLK_LEN; i++)
data[i] ^= mask[i];
data[0] &= (0xff >> 1);
if (!(salt = memchr(data, 0x01, BLK_LEN)))
return CL_EVERIFY;
salt++;
if (data + BLK_LEN - salt != SALT_LEN)
return CL_EVERIFY;
memset(final, 0, 8);
memcpy(&final[8], sha256, HASH_LEN);
memcpy(&final[8 + HASH_LEN], salt, SALT_LEN);
ctx = cl_hash_init("sha256");
if (!(ctx))
return CL_EMEM;
cl_update_hash(ctx, final, sizeof(final));
cl_finish_hash(ctx, digest1);
return memcmp(digest1, digest2, HASH_LEN) ? CL_EVERIFY : CL_SUCCESS;
}