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wolfssh/apps/wolfsshd/auth.c

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/* auth.c
*
* Copyright (C) 2014-2021 wolfSSL Inc.
*
* This file is part of wolfSSH.
*
* wolfSSH is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* wolfSSH 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 wolfSSH. If not, see <http://www.gnu.org/licenses/>.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef WOLFSSH_SSHD
#include <wolfssh/ssh.h>
#include <wolfssh/internal.h>
#include <wolfssh/log.h>
#include <wolfssl/wolfcrypt/wc_port.h>
#include <wolfssl/wolfcrypt/error-crypt.h>
#include <wolfssl/wolfcrypt/coding.h>
#ifdef NO_INLINE
#include <wolfssh/misc.h>
#else
#define WOLFSSH_MISC_INCLUDED
#include "src/misc.c"
#endif
#include "auth.h"
#include <unistd.h>
#ifndef _WIN32
#include <sys/types.h>
#include <pwd.h>
#include <shadow.h>
#include <uuid/uuid.h>
#include <errno.h>
#endif
#if 0
static byte passwdRetry = 3;
/* Map user names to passwords */
/* Use arrays for username and p. The password or public key can
* be hashed and the hash stored here. Then I won't need the type. */
struct USER_NODE {
byte type;
byte username[32];
word32 usernameSz;
byte fingerprint[WC_SHA256_DIGEST_SIZE];
struct USER_NODE* next;
};
/* Takes a users input and adds it to the list of accepted users
* 'value' can be a users password / public key / or certificate
* returns an updated list on success (i.e. 'new' -> 'list' -> ...) or NULL
* on failure
*/
USER_NODE* AddNewUser(USER_NODE* list, byte type, const byte* username,
word32 usernameSz, const byte* value, word32 valueSz)
{
USER_NODE* map;
map = (USER_NODE*)WMALLOC(sizeof(USER_NODE), NULL, 0);
if (map != NULL) {
map->type = type;
if (usernameSz >= sizeof(map->username))
usernameSz = sizeof(map->username) - 1;
WMEMCPY(map->username, username, usernameSz + 1);
map->username[usernameSz] = 0;
map->usernameSz = usernameSz;
if (type != WOLFSSH_USERAUTH_NONE) {
wc_Sha256Hash(value, valueSz, map->fingerprint);
}
map->next = list;
}
return map;
}
int DefaultUserAuth(byte authType, WS_UserAuthData* authData, void* ctx)
{
USER_NODE* map;
byte authHash[WC_SHA256_DIGEST_SIZE];
int ret;
if (authType != WOLFSSH_USERAUTH_PASSWORD &&
#ifdef WOLFSSH_ALLOW_USERAUTH_NONE
authType != WOLFSSH_USERAUTH_NONE &&
#endif
authType != WOLFSSH_USERAUTH_PUBLICKEY) {
return WOLFSSH_USERAUTH_FAILURE;
}
map = (USER_NODE*)ctx;
/* check if password on system */
if (authData->type == WOLFSSH_USERAUTH_PASSWORD) {
if (CheckPassword(authData->username, authData->sf.password.password,
authData->sf.password.passwordSz) == WS_SUCCESS) {
wolfSSH_Log(WS_LOG_INFO, "[SSHD] Password and user on system");
return WOLFSSH_USERAUTH_SUCCESS;
}
}
if (authType == WOLFSSH_USERAUTH_PASSWORD) {
wc_Sha256Hash(authData->sf.password.password,
authData->sf.password.passwordSz,
authHash);
}
else if (authType == WOLFSSH_USERAUTH_PUBLICKEY) {
wc_Sha256Hash(authData->sf.publicKey.publicKey,
authData->sf.publicKey.publicKeySz,
authHash);
}
while (map != NULL) {
if (authData->usernameSz == map->usernameSz &&
WMEMCMP(authData->username, map->username, map->usernameSz) == 0 &&
authData->type == map->type) {
if (authData->type == WOLFSSH_USERAUTH_PUBLICKEY) {
if (WMEMCMP(map->fingerprint, authHash,
WC_SHA256_DIGEST_SIZE) == 0) {
return WOLFSSH_USERAUTH_SUCCESS;
}
else {
return WOLFSSH_USERAUTH_INVALID_PUBLICKEY;
}
}
else if (authData->type == WOLFSSH_USERAUTH_PASSWORD) {
if (WMEMCMP(map->fingerprint, authHash,
WC_SHA256_DIGEST_SIZE) == 0) {
return WOLFSSH_USERAUTH_SUCCESS;
}
else {
passwdRetry--;
return (passwdRetry > 0) ?
WOLFSSH_USERAUTH_INVALID_PASSWORD :
WOLFSSH_USERAUTH_REJECTED;
}
}
#ifdef WOLFSSH_ALLOW_USERAUTH_NONE
else if (authData->type == WOLFSSH_USERAUTH_NONE) {
return WOLFSSH_USERAUTH_SUCCESS;
}
#endif /* WOLFSSH_ALLOW_USERAUTH_NONE */
else {
return WOLFSSH_USERAUTH_INVALID_AUTHTYPE;
}
if (authData->type == map->type) {
if (WMEMCMP(map->fingerprint, authHash,
WC_SHA256_DIGEST_SIZE) == 0) {
return WOLFSSH_USERAUTH_SUCCESS;
}
else {
if (authType == WOLFSSH_USERAUTH_PASSWORD) {
passwdRetry--;
ret = (passwdRetry > 0) ?
WOLFSSH_USERAUTH_INVALID_PASSWORD :
WOLFSSH_USERAUTH_REJECTED;
}
else {
ret = WOLFSSH_USERAUTH_INVALID_PUBLICKEY;
}
return ret;
}
}
else {
return WOLFSSH_USERAUTH_INVALID_AUTHTYPE;
}
}
map = map->next;
}
return WOLFSSH_USERAUTH_INVALID_USER;
}
#endif
enum {
WSSHD_AUTH_FAILURE = 0,
WSSHD_AUTH_SUCCESS = 1
};
static int CheckAuthKeysLine(char* line, word32 lineSz, const byte* key,
word32 keySz)
{
int ret = WSSHD_AUTH_SUCCESS;
char* type;
char* keyCandBase64; /* cand == candidate */
word32 keyCandBase64Sz;
byte* keyCand = NULL;
word32 keyCandSz;
char* last;
enum {
NUM_ALLOWED_TYPES = 5
};
static const char* allowedTypes[NUM_ALLOWED_TYPES] = {
"ssh-rsa",
"ssh-ed25519",
"ecdsa-sha2-nistp256",
"ecdsa-sha2-nistp384",
"ecdsa-sha2-nistp521"
};
int typeOk = 0;
int i;
if (line == NULL || lineSz == 0 || key == NULL || keySz == 0) {
ret = WS_BAD_ARGUMENT;
}
if (ret == WSSHD_AUTH_SUCCESS) {
if ((type = WSTRTOK(line, " ", &last)) == NULL) {
ret = WS_FATAL_ERROR;
}
else if ((keyCandBase64 = WSTRTOK(NULL, " ", &last)) == NULL) {
ret = WS_FATAL_ERROR;
}
}
if (ret == WSSHD_AUTH_SUCCESS) {
for (i = 0; i < NUM_ALLOWED_TYPES; ++i) {
if (WSTRCMP(type, allowedTypes[i]) == 0) {
typeOk = 1;
break;
}
}
if (!typeOk) {
ret = WS_FATAL_ERROR;
}
}
if (ret == WSSHD_AUTH_SUCCESS) {
keyCandBase64Sz = XSTRLEN(keyCandBase64);
keyCandSz = (keyCandBase64Sz * 3 + 3) / 4;
keyCand = (byte*)WMALLOC(keyCandSz, NULL, DYNTYPE_BUFFER);
if (keyCand == NULL) {
ret = WS_MEMORY_E;
}
else {
if (Base64_Decode((byte*)keyCandBase64, keyCandBase64Sz, keyCand,
&keyCandSz) != 0) {
ret = WS_FATAL_ERROR;
}
}
}
if (ret == WSSHD_AUTH_SUCCESS) {
if (keyCandSz != keySz || WMEMCMP(key, keyCand, keySz) != 0) {
ret = WSSHD_AUTH_FAILURE;
}
}
if (keyCand != NULL) {
WFREE(keyCand, NULL, DYNTYPE_BUFFER);
}
return ret;
}
#ifndef _WIN32
static int ExtractSalt(char* hash, char** salt, int saltSz)
{
int ret = WS_SUCCESS;
int idx = 0;
char* p;
if (hash == NULL || salt == NULL || *salt == NULL || saltSz <= 0) {
ret = WS_SUCCESS;
}
if (ret == 0) {
if (hash[idx] != '$') {
ret = WS_FATAL_ERROR;
}
else {
++idx;
if (idx >= saltSz) {
ret = WS_BUFFER_E;
}
}
}
if (ret == 0) {
p = strstr(hash + idx, "$");
if (p == NULL) {
ret = -1;
}
else {
idx += (p - hash);
if (idx >= saltSz) {
ret = WS_BUFFER_E;
}
}
}
if (ret == 0) {
p = strstr(p + 1, "$");
if (p == NULL) {
ret = WS_FATAL_ERROR;
}
else {
idx += (p - (hash + idx) + 1);
if (idx >= saltSz) {
ret = WS_BUFFER_E;
}
}
}
if (ret == 0) {
memcpy(*salt, hash, idx);
(*salt)[idx] = 0;
}
return ret;
}
static int CheckPasswordHashUnix(const char* input, char* stored)
{
int ret = WSSHD_AUTH_SUCCESS;
int rc;
char salt[32];
char* p = salt;
char* hashedInput;
if (input == NULL || stored == NULL) {
ret = WS_BAD_ARGUMENT;
}
if (ret == WSSHD_AUTH_SUCCESS) {
rc = ExtractSalt(stored, &p, sizeof(salt));
if (rc != WS_SUCCESS) {
ret = rc;
}
}
if (ret == WSSHD_AUTH_SUCCESS) {
hashedInput = crypt(input, salt);
if (hashedInput == NULL) {
ret = WS_FATAL_ERROR;
}
else {
if (WMEMCMP(hashedInput, stored, WSTRLEN(stored)) != 0) {
ret = WSSHD_AUTH_FAILURE;
}
}
}
return ret;
}
static int CheckPasswordUnix(const byte* usr, const byte* pw, int pwSz)
{
int ret = WS_SUCCESS;
char* pwStr = NULL;
struct passwd* pwInfo;
struct spwd* shadowInfo;
/* The hash of the user's password stored on the system. */
char* storedHash;
char* storedHashCpy = NULL;
if (usr == NULL || pw == NULL || pwSz < 0) {
ret = WS_BAD_ARGUMENT;
}
if (ret == WS_SUCCESS) {
pwStr = (char*)WMALLOC(pwSz + 1, NULL, DYNTYPE_STRING);
if (pwStr == NULL) {
ret = WS_MEMORY_E;
}
else {
XMEMCPY(pwStr, pw, pwSz);
pwStr[pwSz] = 0;
}
}
pwInfo = getpwnam((const char*)usr);
if (pwInfo == NULL) {
/* user name not found on system */
ret = WS_FATAL_ERROR;
}
if (ret == WS_SUCCESS) {
if (pwInfo->pw_passwd[0] == 'x') {
shadowInfo = getspnam((const char*)usr);
if (shadowInfo == NULL) {
ret = WS_FATAL_ERROR;
}
else {
storedHash = shadowInfo->sp_pwdp;
}
}
else {
storedHash = pwInfo->pw_passwd;
}
}
if (ret == WS_SUCCESS) {
storedHashCpy = WSTRDUP(storedHash, NULL, DYNTYPE_STRING);
if (storedHash == NULL) {
ret = WS_MEMORY_E;
}
}
if (ret == WS_SUCCESS) {
ret = CheckPasswordHashUnix(pwStr, storedHashCpy);
}
if (pwStr != NULL) {
WFREE(pwStr, NULL, DYNTYPE_STRING);
}
if (storedHashCpy != NULL) {
WFREE(storedHashCpy, NULL, DYNTYPE_STRING);
}
return ret;
}
#endif /* !_WIN32 */
#ifndef _WIN32
static int CheckUserUnix(const char* name) {
int ret = WSSHD_AUTH_FAILURE;
struct passwd* pwInfo;
errno = 0;
pwInfo = getpwnam(name);
if (pwInfo == NULL) {
if (errno != 0) {
wolfSSH_Log(WS_LOG_ERROR, "[SSHD] Error calling getpwnam for user "
"%s.", name);
ret = WS_FATAL_ERROR;
}
}
else {
ret = WSSHD_AUTH_SUCCESS;
}
return ret;
}
static const char authKeysDefault[] = ".ssh/authorized_keys";
static char authKeysPattern[32] = {0};
void SetAuthKeysPattern(const char* pattern)
{
if (pattern != NULL) {
WMEMSET(authKeysPattern, 0, sizeof(authKeysPattern));
WSTRNCPY(authKeysPattern, pattern, sizeof(authKeysPattern));
}
}
static int ResolveAuthKeysPath(const char* homeDir, char* resolved)
{
int ret = WS_SUCCESS;
char* idx;
int homeDirSz;
const char* suffix = authKeysDefault;
if (homeDir == NULL || resolved == NULL) {
ret = WS_BAD_ARGUMENT;
}
if (ret == WS_SUCCESS) {
if (*authKeysPattern != 0) {
/* TODO: token substitutions (e.g. %h) */
if (*authKeysPattern == '/') {
/* TODO: handle absolute path case */
ret = WS_FATAL_ERROR;
}
else {
suffix = authKeysPattern;
}
}
}
if (ret == WS_SUCCESS) {
idx = resolved;
homeDirSz = XSTRLEN(homeDir);
XMEMCPY(idx, homeDir, homeDirSz);
idx += homeDirSz;
*(idx++) = '/';
/* Intentionally copying the null term from suffix. */
XMEMCPY(idx, suffix, WSTRLEN(suffix));
}
return ret;
}
static int CheckPublicKeyUnix(const byte* name, const byte* key, word32 keySz)
{
int ret = WSSHD_AUTH_SUCCESS;
int rc;
struct passwd* pwInfo;
char* authKeysFile = NULL;
XFILE f;
enum {
/* TODO: Probably needs to be even bigger for larger key sizes. */
MAX_LINE_SZ = 500,
MAX_PATH_SZ = 80
};
char* lineBuf = NULL;
char* current;
word32 currentSz;
int foundKey = 0;
char authKeysPath[MAX_PATH_SZ];
errno = 0;
pwInfo = getpwnam((const char*)name);
if (pwInfo == NULL) {
if (errno != 0) {
wolfSSH_Log(WS_LOG_ERROR, "[SSHD] Error calling getpwnam for user "
"%s.", name);
ret = WS_FATAL_ERROR;
}
}
if (ret == WSSHD_AUTH_SUCCESS) {
WMEMSET(authKeysPath, 0, sizeof(authKeysPath));
rc = ResolveAuthKeysPath(pwInfo->pw_dir, authKeysPath);
if (rc != WS_SUCCESS) {
wolfSSH_Log(WS_LOG_ERROR, "[SSHD] Failed to resolve authorized keys"
" file path.");
ret = rc;
}
}
if (ret == WSSHD_AUTH_SUCCESS) {
f = XFOPEN(authKeysPath, "rb");
if (f == XBADFILE) {
wolfSSH_Log(WS_LOG_ERROR, "[SSHD] Unable to open %s",
authKeysPath);
ret = WS_BAD_FILE_E;
}
}
if (ret == WSSHD_AUTH_SUCCESS) {
lineBuf = (char*)WMALLOC(MAX_LINE_SZ, NULL, DYNTYPE_BUFFER);
if (lineBuf == NULL) {
ret = WS_MEMORY_E;
}
}
while (ret == WSSHD_AUTH_SUCCESS &&
(current = XFGETS(lineBuf, MAX_LINE_SZ, f)) != NULL) {
currentSz = XSTRLEN(current);
/* remove leading spaces */
while (currentSz > 0 && current[0] == ' ') {
currentSz = currentSz - 1;
current = current + 1;
}
if (currentSz <= 1) {
continue; /* empty line */
}
if (current[0] == '#') {
continue; /* commented out line */
}
rc = CheckAuthKeysLine(current, currentSz, key, keySz);
if (rc == WSSHD_AUTH_SUCCESS) {
foundKey = 1;
break;
}
else if (rc < 0) {
ret = rc;
break;
}
}
XFCLOSE(f);
if (ret == WSSHD_AUTH_SUCCESS && !foundKey) {
ret = WSSHD_AUTH_FAILURE;
}
if (lineBuf != NULL) {
WFREE(lineBuf, NULL, DYNTYPE_BUFFER);
}
if (authKeysFile != NULL) {
WFREE(authKeysFile, NULL, DYNTYPE_STRING);
}
return ret;
}
#endif /* !_WIN32*/
/*
* Returns WSSHD_AUTH_SUCCESS if user found, WSSHD_AUTH_FAILURE if user not
* found, and negative values if an error occurs during checking.
*/
static int CheckUser(const char* name)
{
int ret = WSSHD_AUTH_FAILURE;
#ifdef _WIN32
/* TODO: Implement for Windows. */
#else
ret = CheckUserUnix(name);
#endif
return ret;
}
/*
* Returns WSSHD_AUTH_SUCCESS if user found, WSSHD_AUTH_FAILURE if user not
* found, and negative values if an error occurs during checking.
*/
static int CheckPassword(const byte* usr, const byte* pw, int pwSz)
{
#ifdef _WIN32
/* TODO: Add CheckPasswordWin. */
#else
return CheckPasswordUnix(usr, pw, pwSz);
#endif
}
/*
* Returns WSSHD_AUTH_SUCCESS if public key ok, WSSHD_AUTH_FAILURE if key not
* ok, and negative values if an error occurs during checking.
*/
static int CheckPublicKey(const byte* name, const byte* key, word32 keySz)
{
int ret = 0;
#ifdef _WIN32
/* TODO: Implement for Windows. */
#else
ret = CheckPublicKeyUnix(name, key, keySz);
#endif
return ret;
}
int DefaultUserAuth(byte authType, WS_UserAuthData* authData, void* ctx)
{
int ret = WOLFSSH_USERAUTH_SUCCESS;
int rc;
(void)ctx;
/* TODO: Auth will need some info from the config. For example, the auth
* keys file path or the allowed users, if not all users are allowed. Could
* pass the config in the ctx pointer...
*/
if (authType != WOLFSSH_USERAUTH_PASSWORD &&
#ifdef WOLFSSH_ALLOW_USERAUTH_NONE
authType != WOLFSSH_USERAUTH_NONE &&
#endif
authType != WOLFSSH_USERAUTH_PUBLICKEY) {
ret = WOLFSSH_USERAUTH_INVALID_AUTHTYPE;
}
/* Check user exists. */
/* TODO: Is authData and its members guaranteed to be non-NULL? */
rc = CheckUser((const char*)authData->username);
if (rc == WSSHD_AUTH_SUCCESS) {
wolfSSH_Log(WS_LOG_INFO, "[SSHD] User ok.");
}
else if (ret == WSSHD_AUTH_FAILURE) {
wolfSSH_Log(WS_LOG_INFO, "[SSHD] User %s doesn't exist.",
authData->username);
ret = WOLFSSH_USERAUTH_INVALID_USER;
}
else {
wolfSSH_Log(WS_LOG_ERROR, "[SSHD] Error looking up user %s.",
authData->username);
ret = WOLFSSH_USERAUTH_FAILURE;
}
if (ret == WOLFSSH_USERAUTH_SUCCESS) {
/* Check if password is valid for this user. */
if (authData->type == WOLFSSH_USERAUTH_PASSWORD) {
rc = CheckPassword(authData->username,
authData->sf.password.password,
authData->sf.password.passwordSz);
if (rc == WSSHD_AUTH_SUCCESS) {
wolfSSH_Log(WS_LOG_INFO, "[SSHD] Password ok.");
}
else if (rc == WSSHD_AUTH_FAILURE) {
wolfSSH_Log(WS_LOG_INFO, "[SSHD] Password incorrect.");
ret = WOLFSSH_USERAUTH_INVALID_PASSWORD;
}
else {
wolfSSH_Log(WS_LOG_ERROR, "[SSHD] Error checking password.");
ret = WOLFSSH_USERAUTH_FAILURE;
}
}
/* Check if public key is in this user's authorized_keys file. */
else if (authData->type == WOLFSSH_USERAUTH_PUBLICKEY) {
rc = CheckPublicKey(authData->username,
authData->sf.publicKey.publicKey,
authData->sf.publicKey.publicKeySz);
if (rc == WSSHD_AUTH_SUCCESS) {
wolfSSH_Log(WS_LOG_INFO, "[SSHD] Public key ok.");
ret = WOLFSSH_USERAUTH_SUCCESS;
}
else if (rc == WSSHD_AUTH_FAILURE) {
wolfSSH_Log(WS_LOG_INFO, "[SSHD] Public key not authorized.");
ret = WOLFSSH_USERAUTH_INVALID_PUBLICKEY;
}
else {
wolfSSH_Log(WS_LOG_ERROR, "[SSHD] Error checking public key.");
ret = WOLFSSH_USERAUTH_FAILURE;
}
}
}
return ret;
}
#endif /* WOLFSSH_SSHD */
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