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gerrit.cesnet.cz / github / CESNET / libnetconf2 / 2f76655055b88d78b6c1dc07a992034d35a17439 / . / src / session_server_ssh.c
blob: 9907a331c94baec2e4fedee19cea4af2d63721f7 [file] [log] [blame]
/**
* @file session_server_ssh.c
* @author Michal Vasko <mvasko@cesnet.cz>
* @brief libnetconf2 SSH server session manipulation functions
*
* @copyright
* Copyright (c) 2017 - 2021 CESNET, z.s.p.o.
*
* This source code is licensed under BSD 3-Clause License (the "License").
* You may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://opensource.org/licenses/BSD-3-Clause
*/
#define _GNU_SOURCE
#include "config.h" /* Expose HAVE_SHADOW and HAVE_CRYPT */
#ifdef HAVE_SHADOW
#include <shadow.h>
#endif
#ifdef HAVE_CRYPT
#include <crypt.h>
#endif
#ifdef HAVE_LIBPAM
#include <security/pam_appl.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#include "compat.h"
#include "libnetconf.h"
#include "session_server.h"
#include "session_server_ch.h"
#if !defined (HAVE_CRYPT_R)
pthread_mutex_t crypt_lock = PTHREAD_MUTEX_INITIALIZER;
#endif
extern struct nc_server_opts server_opts;
static char *
base64der_key_to_tmp_file(const char *in, const char *key_str)
{
char path[12] = "/tmp/XXXXXX";
int fd, written;
mode_t umode;
FILE *file;
if (in == NULL) {
return NULL;
}
umode = umask(0177);
fd = mkstemp(path);
umask(umode);
if (fd == -1) {
return NULL;
}
file = fdopen(fd, "w");
if (!file) {
close(fd);
return NULL;
}
/* write the key into the file */
if (key_str) {
written = fwrite("-----BEGIN ", 1, 11, file);
written += fwrite(key_str, 1, strlen(key_str), file);
written += fwrite(" PRIVATE KEY-----\n", 1, 18, file);
written += fwrite(in, 1, strlen(in), file);
written += fwrite("\n-----END ", 1, 10, file);
written += fwrite(key_str, 1, strlen(key_str), file);
written += fwrite(" PRIVATE KEY-----", 1, 17, file);
fclose(file);
if ((unsigned)written != 11 + strlen(key_str) + 18 + strlen(in) + 10 + strlen(key_str) + 17) {
unlink(path);
return NULL;
}
} else {
written = fwrite("-----BEGIN PRIVATE KEY-----\n", 1, 28, file);
written += fwrite(in, 1, strlen(in), file);
written += fwrite("\n-----END PRIVATE KEY-----", 1, 26, file);
fclose(file);
if ((unsigned)written != 28 + strlen(in) + 26) {
unlink(path);
return NULL;
}
}
return strdup(path);
}
static int
nc_server_ssh_add_hostkey(const char *name, int16_t idx, struct nc_server_ssh_opts *opts)
{
uint8_t i;
if (!name) {
ERRARG("name");
return -1;
} else if (idx > opts->hostkey_count) {
ERRARG("idx");
return -1;
}
for (i = 0; i < opts->hostkey_count; ++i) {
if (!strcmp(opts->hostkeys[i], name)) {
ERRARG("name");
return -1;
}
}
++opts->hostkey_count;
opts->hostkeys = nc_realloc(opts->hostkeys, opts->hostkey_count * sizeof *opts->hostkeys);
if (!opts->hostkeys) {
ERRMEM;
return -1;
}
if (idx < 0) {
idx = opts->hostkey_count - 1;
}
if (idx != opts->hostkey_count - 1) {
memmove(opts->hostkeys + idx + 1, opts->hostkeys + idx, opts->hostkey_count - idx);
}
opts->hostkeys[idx] = strdup(name);
return 0;
}
API int
nc_server_ssh_endpt_add_hostkey(const char *endpt_name, const char *name, int16_t idx)
{
int ret;
struct nc_endpt *endpt;
/* LOCK */
endpt = nc_server_endpt_lock_get(endpt_name, NC_TI_LIBSSH, NULL);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_add_hostkey(name, idx, endpt->opts.ssh);
/* UNLOCK */
pthread_rwlock_unlock(&server_opts.endpt_lock);
return ret;
}
API void
nc_server_ssh_set_passwd_auth_clb(int (*passwd_auth_clb)(const struct nc_session *session, const char *password, void *user_data),
void *user_data, void (*free_user_data)(void *user_data))
{
server_opts.passwd_auth_clb = passwd_auth_clb;
server_opts.passwd_auth_data = user_data;
server_opts.passwd_auth_data_free = free_user_data;
}
API void
nc_server_ssh_set_interactive_auth_clb(int (*interactive_auth_clb)(const struct nc_session *session, ssh_message msg, void *user_data),
void *user_data, void (*free_user_data)(void *user_data))
{
server_opts.interactive_auth_clb = interactive_auth_clb;
server_opts.interactive_auth_data = user_data;
server_opts.interactive_auth_data_free = free_user_data;
}
API int
nc_server_ssh_set_pam_conf_path(const char *conf_name, const char *conf_dir)
{
#ifdef HAVE_LIBPAM
free(server_opts.conf_name);
free(server_opts.conf_dir);
server_opts.conf_name = NULL;
server_opts.conf_dir = NULL;
if (conf_dir) {
# ifdef LIBPAM_HAVE_CONFDIR
server_opts.conf_dir = strdup(conf_dir);
if (!(server_opts.conf_dir)) {
ERRMEM;
return -1;
}
# else
ERR(NULL, "Failed to set PAM config directory because of old version of PAM. "
"Put the config file in the system directory (usually /etc/pam.d/).");
return -1;
# endif
}
if (conf_name) {
server_opts.conf_name = strdup(conf_name);
if (!(server_opts.conf_name)) {
ERRMEM;
return -1;
}
}
return 0;
#else
(void)conf_name;
(void)conf_dir;
ERR(NULL, "PAM-based SSH authentication is not supported.");
return -1;
#endif
}
API void
nc_server_ssh_set_pubkey_auth_clb(int (*pubkey_auth_clb)(const struct nc_session *session, ssh_key key, void *user_data),
void *user_data, void (*free_user_data)(void *user_data))
{
server_opts.pubkey_auth_clb = pubkey_auth_clb;
server_opts.pubkey_auth_data = user_data;
server_opts.pubkey_auth_data_free = free_user_data;
}
API int
nc_server_ssh_ch_client_endpt_add_hostkey(const char *client_name, const char *endpt_name, const char *name, int16_t idx)
{
int ret;
struct nc_ch_client *client;
struct nc_ch_endpt *endpt;
/* LOCK */
endpt = nc_server_ch_client_lock(client_name, endpt_name, NC_TI_LIBSSH, &client);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_add_hostkey(name, idx, endpt->opts.ssh);
/* UNLOCK */
nc_server_ch_client_unlock(client);
return ret;
}
API void
nc_server_ssh_set_hostkey_clb(int (*hostkey_clb)(const char *name, void *user_data, char **privkey_path,
char **privkey_data, NC_SSH_KEY_TYPE *privkey_type), void *user_data, void (*free_user_data)(void *user_data))
{
if (!hostkey_clb) {
ERRARG("hostkey_clb");
return;
}
server_opts.hostkey_clb = hostkey_clb;
server_opts.hostkey_data = user_data;
server_opts.hostkey_data_free = free_user_data;
}
static int
nc_server_ssh_del_hostkey(const char *name, int16_t idx, struct nc_server_ssh_opts *opts)
{
uint8_t i;
if (name && (idx > -1)) {
ERRARG("name and idx");
return -1;
} else if (idx >= opts->hostkey_count) {
ERRARG("idx");
}
if (!name && (idx < 0)) {
for (i = 0; i < opts->hostkey_count; ++i) {
free(opts->hostkeys[i]);
}
free(opts->hostkeys);
opts->hostkeys = NULL;
opts->hostkey_count = 0;
} else if (name) {
for (i = 0; i < opts->hostkey_count; ++i) {
if (!strcmp(opts->hostkeys[i], name)) {
idx = i;
goto remove_idx;
}
}
ERRARG("name");
return -1;
} else {
remove_idx:
--opts->hostkey_count;
free(opts->hostkeys[idx]);
if (idx < opts->hostkey_count - 1) {
memmove(opts->hostkeys + idx, opts->hostkeys + idx + 1, (opts->hostkey_count - idx) * sizeof *opts->hostkeys);
}
if (!opts->hostkey_count) {
free(opts->hostkeys);
opts->hostkeys = NULL;
}
}
return 0;
}
API int
nc_server_ssh_endpt_del_hostkey(const char *endpt_name, const char *name, int16_t idx)
{
int ret;
struct nc_endpt *endpt;
/* LOCK */
endpt = nc_server_endpt_lock_get(endpt_name, NC_TI_LIBSSH, NULL);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_del_hostkey(name, idx, endpt->opts.ssh);
/* UNLOCK */
pthread_rwlock_unlock(&server_opts.endpt_lock);
return ret;
}
API int
nc_server_ssh_ch_client_endpt_del_hostkey(const char *client_name, const char *endpt_name, const char *name, int16_t idx)
{
int ret;
struct nc_ch_client *client;
struct nc_ch_endpt *endpt;
/* LOCK */
endpt = nc_server_ch_client_lock(client_name, endpt_name, NC_TI_LIBSSH, &client);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_del_hostkey(name, idx, endpt->opts.ssh);
/* UNLOCK */
nc_server_ch_client_unlock(client);
return ret;
}
static int
nc_server_ssh_mov_hostkey(const char *key_mov, const char *key_after, struct nc_server_ssh_opts *opts)
{
uint8_t i;
int16_t mov_idx = -1, after_idx = -1;
char *bckup;
if (!key_mov) {
ERRARG("key_mov");
return -1;
}
for (i = 0; i < opts->hostkey_count; ++i) {
if (key_after && (after_idx == -1) && !strcmp(opts->hostkeys[i], key_after)) {
after_idx = i;
}
if ((mov_idx == -1) && !strcmp(opts->hostkeys[i], key_mov)) {
mov_idx = i;
}
if ((!key_after || (after_idx > -1)) && (mov_idx > -1)) {
break;
}
}
if (key_after && (after_idx == -1)) {
ERRARG("key_after");
return -1;
}
if (mov_idx == -1) {
ERRARG("key_mov");
return -1;
}
if ((mov_idx == after_idx) || (mov_idx == after_idx + 1)) {
/* nothing to do */
return 0;
}
/* finally move the key */
bckup = opts->hostkeys[mov_idx];
if (mov_idx > after_idx) {
memmove(opts->hostkeys + after_idx + 2, opts->hostkeys + after_idx + 1,
((mov_idx - after_idx) - 1) * sizeof *opts->hostkeys);
opts->hostkeys[after_idx + 1] = bckup;
} else {
memmove(opts->hostkeys + mov_idx, opts->hostkeys + mov_idx + 1, (after_idx - mov_idx) * sizeof *opts->hostkeys);
opts->hostkeys[after_idx] = bckup;
}
return 0;
}
API int
nc_server_ssh_endpt_mov_hostkey(const char *endpt_name, const char *key_mov, const char *key_after)
{
int ret;
struct nc_endpt *endpt;
/* LOCK */
endpt = nc_server_endpt_lock_get(endpt_name, NC_TI_LIBSSH, NULL);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_mov_hostkey(key_mov, key_after, endpt->opts.ssh);
/* UNLOCK */
pthread_rwlock_unlock(&server_opts.endpt_lock);
return ret;
}
API int
nc_server_ssh_ch_client_endpt_mov_hostkey(const char *client_name, const char *endpt_name, const char *key_mov,
const char *key_after)
{
int ret;
struct nc_ch_client *client;
struct nc_ch_endpt *endpt;
/* LOCK */
endpt = nc_server_ch_client_lock(client_name, endpt_name, NC_TI_LIBSSH, &client);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_mov_hostkey(key_mov, key_after, endpt->opts.ssh);
/* UNLOCK */
nc_server_ch_client_unlock(client);
return ret;
}
static int
nc_server_ssh_set_auth_methods(int auth_methods, struct nc_server_ssh_opts *opts)
{
if ((auth_methods & NC_SSH_AUTH_INTERACTIVE) && !server_opts.conf_name) {
/* path to a configuration file not set */
ERR(NULL, "Unable to use Keyboard-Interactive authentication method without setting the name of the PAM configuration file first.");
return 1;
}
opts->auth_methods = auth_methods;
return 0;
}
API int
nc_server_ssh_endpt_set_auth_methods(const char *endpt_name, int auth_methods)
{
int ret;
struct nc_endpt *endpt;
/* LOCK */
endpt = nc_server_endpt_lock_get(endpt_name, NC_TI_LIBSSH, NULL);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_set_auth_methods(auth_methods, endpt->opts.ssh);
/* UNLOCK */
pthread_rwlock_unlock(&server_opts.endpt_lock);
return ret;
}
API int
nc_server_ssh_ch_client_endpt_set_auth_methods(const char *client_name, const char *endpt_name, int auth_methods)
{
int ret;
struct nc_ch_client *client;
struct nc_ch_endpt *endpt;
/* LOCK */
endpt = nc_server_ch_client_lock(client_name, endpt_name, NC_TI_LIBSSH, &client);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_set_auth_methods(auth_methods, endpt->opts.ssh);
/* UNLOCK */
nc_server_ch_client_unlock(client);
return ret;
}
API int
nc_server_ssh_endpt_get_auth_methods(const char *endpt_name)
{
int ret;
struct nc_endpt *endpt;
/* LOCK */
endpt = nc_server_endpt_lock_get(endpt_name, NC_TI_LIBSSH, NULL);
if (!endpt) {
return -1;
}
ret = endpt->opts.ssh->auth_methods;
/* UNLOCK */
pthread_rwlock_unlock(&server_opts.endpt_lock);
return ret;
}
API int
nc_server_ssh_ch_client_endpt_get_auth_methods(const char *client_name, const char *endpt_name)
{
int ret;
struct nc_ch_client *client;
struct nc_ch_endpt *endpt;
/* LOCK */
endpt = nc_server_ch_client_lock(client_name, endpt_name, NC_TI_LIBSSH, &client);
if (!endpt) {
return -1;
}
ret = endpt->opts.ssh->auth_methods;
/* UNLOCK */
nc_server_ch_client_unlock(client);
return ret;
}
static int
nc_server_ssh_set_auth_attempts(uint16_t auth_attempts, struct nc_server_ssh_opts *opts)
{
if (!auth_attempts) {
ERRARG("auth_attempts");
return -1;
}
opts->auth_attempts = auth_attempts;
return 0;
}
API int
nc_server_ssh_endpt_set_auth_attempts(const char *endpt_name, uint16_t auth_attempts)
{
int ret;
struct nc_endpt *endpt;
/* LOCK */
endpt = nc_server_endpt_lock_get(endpt_name, NC_TI_LIBSSH, NULL);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_set_auth_attempts(auth_attempts, endpt->opts.ssh);
/* UNLOCK */
pthread_rwlock_unlock(&server_opts.endpt_lock);
return ret;
}
API int
nc_server_ssh_ch_client_endpt_set_auth_attempts(const char *client_name, const char *endpt_name, uint16_t auth_attempts)
{
int ret;
struct nc_ch_client *client;
struct nc_ch_endpt *endpt;
/* LOCK */
endpt = nc_server_ch_client_lock(client_name, endpt_name, NC_TI_LIBSSH, &client);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_set_auth_attempts(auth_attempts, endpt->opts.ssh);
/* UNLOCK */
nc_server_ch_client_unlock(client);
return ret;
}
static int
nc_server_ssh_set_auth_timeout(uint16_t auth_timeout, struct nc_server_ssh_opts *opts)
{
if (!auth_timeout) {
ERRARG("auth_timeout");
return -1;
}
opts->auth_timeout = auth_timeout;
return 0;
}
API int
nc_server_ssh_endpt_set_auth_timeout(const char *endpt_name, uint16_t auth_timeout)
{
int ret;
struct nc_endpt *endpt;
/* LOCK */
endpt = nc_server_endpt_lock_get(endpt_name, NC_TI_LIBSSH, NULL);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_set_auth_timeout(auth_timeout, endpt->opts.ssh);
/* UNLOCK */
pthread_rwlock_unlock(&server_opts.endpt_lock);
return ret;
}
API int
nc_server_ssh_ch_client_endpt_set_auth_timeout(const char *client_name, const char *endpt_name, uint16_t auth_timeout)
{
int ret;
struct nc_ch_client *client;
struct nc_ch_endpt *endpt;
/* LOCK */
endpt = nc_server_ch_client_lock(client_name, endpt_name, NC_TI_LIBSSH, &client);
if (!endpt) {
return -1;
}
ret = nc_server_ssh_set_auth_timeout(auth_timeout, endpt->opts.ssh);
/* UNLOCK */
nc_server_ch_client_unlock(client);
return ret;
}
static int
_nc_server_ssh_add_authkey(const char *pubkey_path, const char *pubkey_base64, NC_SSH_KEY_TYPE type, const char *username)
{
int ret = 0;
/* LOCK */
pthread_mutex_lock(&server_opts.authkey_lock);
++server_opts.authkey_count;
server_opts.authkeys = nc_realloc(server_opts.authkeys, server_opts.authkey_count * sizeof *server_opts.authkeys);
if (!server_opts.authkeys) {
ERRMEM;
ret = -1;
goto cleanup;
}
server_opts.authkeys[server_opts.authkey_count - 1].path = pubkey_path ? strdup(pubkey_path) : NULL;
server_opts.authkeys[server_opts.authkey_count - 1].base64 = pubkey_base64 ? strdup(pubkey_base64) : NULL;
server_opts.authkeys[server_opts.authkey_count - 1].type = type;
server_opts.authkeys[server_opts.authkey_count - 1].username = strdup(username);
cleanup:
/* UNLOCK */
pthread_mutex_unlock(&server_opts.authkey_lock);
return ret;
}
API int
nc_server_ssh_add_authkey_path(const char *pubkey_path, const char *username)
{
if (!pubkey_path) {
ERRARG("pubkey_path");
return -1;
} else if (!username) {
ERRARG("username");
return -1;
}
return _nc_server_ssh_add_authkey(pubkey_path, NULL, 0, username);
}
API int
nc_server_ssh_add_authkey(const char *pubkey_base64, NC_SSH_KEY_TYPE type, const char *username)
{
if (!pubkey_base64) {
ERRARG("pubkey_base64");
return -1;
} else if (!type) {
ERRARG("type");
return -1;
} else if (!username) {
ERRARG("username");
return -1;
}
return _nc_server_ssh_add_authkey(NULL, pubkey_base64, type, username);
}
API int
nc_server_ssh_del_authkey(const char *pubkey_path, const char *pubkey_base64, NC_SSH_KEY_TYPE type,
const char *username)
{
uint32_t i;
int ret = -1;
/* LOCK */
pthread_mutex_lock(&server_opts.authkey_lock);
if (!pubkey_path && !pubkey_base64 && !type && !username) {
for (i = 0; i < server_opts.authkey_count; ++i) {
free(server_opts.authkeys[i].path);
free(server_opts.authkeys[i].base64);
free(server_opts.authkeys[i].username);
ret = 0;
}
free(server_opts.authkeys);
server_opts.authkeys = NULL;
server_opts.authkey_count = 0;
} else {
for (i = 0; i < server_opts.authkey_count; ++i) {
if ((!pubkey_path || !strcmp(server_opts.authkeys[i].path, pubkey_path)) &&
(!pubkey_base64 || !strcmp(server_opts.authkeys[i].base64, pubkey_base64)) &&
(!type || (server_opts.authkeys[i].type == type)) &&
(!username || !strcmp(server_opts.authkeys[i].username, username))) {
free(server_opts.authkeys[i].path);
free(server_opts.authkeys[i].base64);
free(server_opts.authkeys[i].username);
--server_opts.authkey_count;
if (i < server_opts.authkey_count) {
memcpy(&server_opts.authkeys[i], &server_opts.authkeys[server_opts.authkey_count],
sizeof *server_opts.authkeys);
} else if (!server_opts.authkey_count) {
free(server_opts.authkeys);
server_opts.authkeys = NULL;
}
ret = 0;
}
}
}
/* UNLOCK */
pthread_mutex_unlock(&server_opts.authkey_lock);
return ret;
}
void
nc_server_ssh_clear_opts(struct nc_server_ssh_opts *opts)
{
nc_server_ssh_del_hostkey(NULL, -1, opts);
}
#ifdef HAVE_SHADOW
/**
* @brief Get passwd entry for a user.
*
* @param[in] username Name of the user.
* @param[in] pwd_buf Passwd entry buffer.
* @param[in,out] buf Passwd entry string buffer.
* @param[in,out] buf_size Current @p buf size.
* @return Found passwd entry for the user, NULL if none found.
*/
static struct passwd *
auth_password_getpwnam(const char *username, struct passwd *pwd_buf, char **buf, size_t *buf_size)
{
struct passwd *pwd = NULL;
char *mem;
int r = 0;
do {
r = getpwnam_r(username, pwd_buf, *buf, *buf_size, &pwd);
if (pwd) {
/* entry found */
break;
}
if (r == ERANGE) {
/* small buffer, enlarge */
*buf_size <<= 2;
mem = realloc(*buf, *buf_size);
if (!mem) {
ERRMEM;
return NULL;
}
*buf = mem;
}
} while (r == ERANGE);
return pwd;
}
/**
* @brief Get shadow entry for a user.
*
* @param[in] username Name of the user.
* @param[in] spwd_buf Shadow entry buffer.
* @param[in,out] buf Shadow entry string buffer.
* @param[in,out] buf_size Current @p buf size.
* @return Found shadow entry for the user, NULL if none found.
*/
static struct spwd *
auth_password_getspnam(const char *username, struct spwd *spwd_buf, char **buf, size_t *buf_size)
{
struct spwd *spwd = NULL;
char *mem;
int r = 0;
do {
# ifndef __QNXNTO__
r = getspnam_r(username, spwd_buf, *buf, *buf_size, &spwd);
# else
spwd = getspnam_r(username, spwd_buf, *buf, *buf_size);
# endif
if (spwd) {
/* entry found */
break;
}
if (r == ERANGE) {
/* small buffer, enlarge */
*buf_size <<= 2;
mem = realloc(*buf, *buf_size);
if (!mem) {
ERRMEM;
return NULL;
}
*buf = mem;
}
} while (r == ERANGE);
return spwd;
}
/**
* @brief Get hashed system apssword for a user.
*
* @param[in] username Name of the user.
* @return Hashed password of @p username.
*/
static char *
auth_password_get_pwd_hash(const char *username)
{
struct passwd *pwd, pwd_buf;
struct spwd *spwd, spwd_buf;
char *pass_hash = NULL, *buf = NULL;
size_t buf_size = 256;
buf = malloc(buf_size);
if (!buf) {
ERRMEM;
goto error;
}
pwd = auth_password_getpwnam(username, &pwd_buf, &buf, &buf_size);
if (!pwd) {
VRB(NULL, "User \"%s\" not found locally.", username);
goto error;
}
if (!strcmp(pwd->pw_passwd, "x")) {
spwd = auth_password_getspnam(username, &spwd_buf, &buf, &buf_size);
if (!spwd) {
VRB(NULL, "Failed to retrieve the shadow entry for \"%s\".", username);
goto error;
} else if ((spwd->sp_expire > -1) && (spwd->sp_expire <= (time(NULL) / (60 * 60 * 24)))) {
WRN(NULL, "User \"%s\" account has expired.", username);
goto error;
}
pass_hash = spwd->sp_pwdp;
} else {
pass_hash = pwd->pw_passwd;
}
if (!pass_hash) {
ERR(NULL, "No password could be retrieved for \"%s\".", username);
goto error;
}
/* check the hash structure for special meaning */
if (!strcmp(pass_hash, "*") || !strcmp(pass_hash, "!")) {
VRB(NULL, "User \"%s\" is not allowed to authenticate using a password.", username);
goto error;
}
if (!strcmp(pass_hash, "*NP*")) {
VRB(NULL, "Retrieving password for \"%s\" from a NIS+ server not supported.", username);
goto error;
}
pass_hash = strdup(pass_hash);
free(buf);
return pass_hash;
error:
free(buf);
return NULL;
}
#else
/**
* @brief Get hashed system password for a user.
*
* @param[in] username Name of the user.
* @return Hashed password of @p username.
*/
static char *
auth_password_get_pwd_hash(const char *username)
{
(void)username;
return strdup("");
}
#endif
/**
* @brief Compare hashed password with a cleartext password for a match.
*
* @param[in] pass_hash Hashed password.
* @param[in] pass_clear Cleartext password.
* @return 0 on match.
* @return non-zero if not a match.
*/
static int
auth_password_compare_pwd(const char *pass_hash, const char *pass_clear)
{
char *new_pass_hash;
#ifdef HAVE_CRYPT_R
struct crypt_data cdata;
#endif
if (!pass_hash[0]) {
if (!pass_clear[0]) {
WRN(NULL, "User authentication successful with an empty password!");
return 0;
} else {
/* the user did now know he does not need any password,
* (which should not be used) so deny authentication */
return 1;
}
}
#ifdef HAVE_CRYPT_R
cdata.initialized = 0;
new_pass_hash = crypt_r(pass_clear, pass_hash, &cdata);
#else
pthread_mutex_lock(&crypt_lock);
new_pass_hash = crypt(pass_clear, pass_hash);
pthread_mutex_unlock(&crypt_lock);
#endif
if (!new_pass_hash) {
return 1;
}
return strcmp(new_pass_hash, pass_hash);
}
static void
nc_sshcb_auth_password(struct nc_session *session, ssh_message msg)
{
char *pass_hash;
int auth_ret = 1;
if (server_opts.passwd_auth_clb) {
auth_ret = server_opts.passwd_auth_clb(session, ssh_message_auth_password(msg), server_opts.passwd_auth_data);
} else {
pass_hash = auth_password_get_pwd_hash(session->username);
if (pass_hash) {
auth_ret = auth_password_compare_pwd(pass_hash, ssh_message_auth_password(msg));
free(pass_hash);
}
}
if (!auth_ret) {
session->flags |= NC_SESSION_SSH_AUTHENTICATED;
VRB(session, "User \"%s\" authenticated.", session->username);
ssh_message_auth_reply_success(msg, 0);
} else {
++session->opts.server.ssh_auth_attempts;
VRB(session, "Failed user \"%s\" authentication attempt (#%d).", session->username,
session->opts.server.ssh_auth_attempts);
ssh_message_reply_default(msg);
}
}
#ifdef HAVE_LIBPAM
/**
* @brief PAM conversation function, which serves as a callback for exchanging messages between the client and a PAM module.
*
* @param[in] n_messages Number of messages.
* @param[in] msg PAM module's messages.
* @param[out] resp User responses.
* @param[in] appdata_ptr Callback's data.
* @return PAM_SUCCESS on success;
* @return PAM_BUF_ERR on memory allocation error;
* @return PAM_CONV_ERR otherwise.
*/
static int
nc_pam_conv_clb(int n_messages, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr)
{
int i, j, t, r = PAM_SUCCESS, n_answers, n_requests = n_messages;
const char **prompts = NULL;
char *echo = NULL;
const char *name = "Keyboard-Interactive Authentication";
const char *instruction = "Please enter your authentication token";
ssh_message reply = NULL;
struct nc_pam_thread_arg *clb_data = appdata_ptr;
ssh_session libssh_session;
struct timespec ts_timeout;
struct nc_server_ssh_opts *opts;
libssh_session = clb_data->session->ti.libssh.session;
opts = clb_data->session->data;
/* PAM_MAX_NUM_MSG == 32 by default */
if ((n_messages <= 0) || (n_messages >= PAM_MAX_NUM_MSG)) {
ERR(NULL, "Bad number of PAM messages (#%d).", n_messages);
r = PAM_CONV_ERR;
goto cleanup;
}
/* only accepting these 4 types of messages */
for (i = 0; i < n_messages; i++) {
t = msg[i]->msg_style;
if ((t != PAM_PROMPT_ECHO_OFF) && (t != PAM_PROMPT_ECHO_ON) && (t != PAM_TEXT_INFO) && (t != PAM_ERROR_MSG)) {
ERR(NULL, "PAM conversation callback received an unexpected type of message.");
r = PAM_CONV_ERR;
goto cleanup;
}
}
/* display messages with errors and/or some information and count the amount of actual authentication challenges */
for (i = 0; i < n_messages; i++) {
if (msg[i]->msg_style == PAM_TEXT_INFO) {
VRB(NULL, "PAM conversation callback received a message with some information for the client (%s).", msg[i]->msg);
n_requests--;
}
if (msg[i]->msg_style == PAM_ERROR_MSG) {
ERR(NULL, "PAM conversation callback received an error message (%s).", msg[i]->msg);
r = PAM_CONV_ERR;
goto cleanup;
}
}
/* there are no requests left for the user, only messages with some information for the client were sent */
if (n_requests <= 0) {
r = PAM_SUCCESS;
goto cleanup;
}
/* it is the PAM module's responsibility to release both, this array and the responses themselves */
*resp = calloc(n_requests, sizeof **resp);
prompts = calloc(n_requests, sizeof *prompts);
echo = calloc(n_requests, sizeof *echo);
if (!(*resp) || !prompts || !echo) {
ERRMEM;
r = PAM_BUF_ERR;
goto cleanup;
}
/* set the prompts for the user */
j = 0;
for (i = 0; i < n_messages; i++) {
if ((msg[i]->msg_style == PAM_PROMPT_ECHO_ON) || (msg[i]->msg_style == PAM_PROMPT_ECHO_OFF)) {
prompts[j++] = msg[i]->msg;
}
}
/* iterate over all the messages and adjust the echo array accordingly */
j = 0;
for (i = 0; i < n_messages; i++) {
if (msg[i]->msg_style == PAM_PROMPT_ECHO_ON) {
echo[j++] = 1;
}
if (msg[i]->msg_style == PAM_PROMPT_ECHO_OFF) {
/* no need to set to 0 because of calloc */
j++;
}
}
/* print all the keyboard-interactive challenges to the user */
r = ssh_message_auth_interactive_request(clb_data->msg, name, instruction, n_requests, prompts, echo);
if (r != SSH_OK) {
ERR(NULL, "Failed to send an authentication request.");
r = PAM_CONV_ERR;
goto cleanup;
}
if (opts->auth_timeout) {
nc_gettimespec_mono_add(&ts_timeout, opts->auth_timeout * 1000);
}
/* get user's replies */
do {
if (!nc_session_is_connected(clb_data->session)) {
ERR(NULL, "Communication SSH socket unexpectedly closed.");
r = PAM_CONV_ERR;
goto cleanup;
}
reply = ssh_message_get(libssh_session);
if (reply) {
break;
}
usleep(NC_TIMEOUT_STEP);
} while ((opts->auth_timeout) && (nc_difftimespec_mono_cur(&ts_timeout) >= 1));
if (!reply) {
ERR(NULL, "Authentication timeout.");
r = PAM_CONV_ERR;
goto cleanup;
}
/* check if the amount of replies matches the amount of requests */
n_answers = ssh_userauth_kbdint_getnanswers(libssh_session);
if (n_answers != n_requests) {
ERR(NULL, "Expected %d response(s), got %d.", n_requests, n_answers);
r = PAM_CONV_ERR;
goto cleanup;
}
/* give the replies to a PAM module */
for (i = 0; i < n_answers; i++) {
(*resp)[i].resp = strdup(ssh_userauth_kbdint_getanswer(libssh_session, i));
/* it should be the caller's responsibility to free this, however if mem alloc fails,
* it is safer to free the responses here and set them to NULL */
if ((*resp)[i].resp == NULL) {
for (j = 0; j < i; j++) {
free((*resp)[j].resp);
(*resp)[j].resp = NULL;
}
ERRMEM;
r = PAM_BUF_ERR;
goto cleanup;
}
}
cleanup:
ssh_message_free(reply);
free(prompts);
free(echo);
return r;
}
/**
* @brief Handles authentication via Linux PAM.
*
* @param[in] session NETCONF session.
* @param[in] ssh_msg SSH message with a keyboard-interactive authentication request.
* @return PAM_SUCCESS on success;
* @return PAM error otherwise.
*/
static int
nc_pam_auth(struct nc_session *session, ssh_message ssh_msg)
{
pam_handle_t *pam_h = NULL;
int ret;
struct nc_pam_thread_arg clb_data;
struct pam_conv conv;
/* structure holding callback's data */
clb_data.msg = ssh_msg;
clb_data.session = session;
/* PAM conversation structure holding the callback and it's data */
conv.conv = nc_pam_conv_clb;
conv.appdata_ptr = &clb_data;
/* initialize PAM and see if the given configuration file exists */
# ifdef LIBPAM_HAVE_CONFDIR
/* PAM version >= 1.4 */
ret = pam_start_confdir(server_opts.conf_name, session->username, &conv, server_opts.conf_dir, &pam_h);
# else
/* PAM version < 1.4 */
ret = pam_start(server_opts.conf_name, session->username, &conv, &pam_h);
# endif
if (ret != PAM_SUCCESS) {
ERR(NULL, "PAM error occurred (%s).\n", pam_strerror(pam_h, ret));
goto cleanup;
}
/* authentication based on the modules listed in the configuration file */
ret = pam_authenticate(pam_h, 0);
if (ret != PAM_SUCCESS) {
if (ret == PAM_ABORT) {
ERR(NULL, "PAM error occurred (%s).\n", pam_strerror(pam_h, ret));
goto cleanup;
} else {
VRB(NULL, "PAM error occurred (%s).\n", pam_strerror(pam_h, ret));
goto cleanup;
}
}
/* correct token entered, check other requirements(the time of the day, expired token, ...) */
ret = pam_acct_mgmt(pam_h, 0);
if ((ret != PAM_SUCCESS) && (ret != PAM_NEW_AUTHTOK_REQD)) {
VRB(NULL, "PAM error occurred (%s).\n", pam_strerror(pam_h, ret));
goto cleanup;
}
/* if a token has expired a new one will be generated */
if (ret == PAM_NEW_AUTHTOK_REQD) {
VRB(NULL, "PAM warning occurred (%s).\n", pam_strerror(pam_h, ret));
ret = pam_chauthtok(pam_h, PAM_CHANGE_EXPIRED_AUTHTOK);
if (ret == PAM_SUCCESS) {
VRB(NULL, "The authentication token of user \"%s\" updated successfully.", session->username);
} else {
ERR(NULL, "PAM error occurred (%s).\n", pam_strerror(pam_h, ret));
goto cleanup;
}
}
cleanup:
/* destroy the PAM context */
if (pam_end(pam_h, ret) != PAM_SUCCESS) {
ERR(NULL, "PAM error occurred (%s).\n", pam_strerror(pam_h, ret));
}
return ret;
}
#endif
static void
nc_sshcb_auth_kbdint(struct nc_session *session, ssh_message msg)
{
int auth_ret = 1;
if (server_opts.interactive_auth_clb) {
auth_ret = server_opts.interactive_auth_clb(session, msg, server_opts.interactive_auth_data);
} else {
#ifdef HAVE_LIBPAM
if (nc_pam_auth(session, msg) == PAM_SUCCESS) {
auth_ret = 0;
}
#else
ERR(session, "PAM-based SSH authentication is not supported.");
#endif
}
/* We have already sent a reply */
if (auth_ret == -1) {
return;
}
/* Authenticate message based on outcome */
if (!auth_ret) {
session->flags |= NC_SESSION_SSH_AUTHENTICATED;
VRB(session, "User \"%s\" authenticated.", session->username);
ssh_message_auth_reply_success(msg, 0);
} else {
++session->opts.server.ssh_auth_attempts;
VRB(session, "Failed user \"%s\" authentication attempt (#%d).", session->username,
session->opts.server.ssh_auth_attempts);
ssh_message_reply_default(msg);
}
}
/**
* @brief Compare SSH key with configured authorized keys and return the username of the matching one, if any.
*
* @param[in] key Presented SSH key to compare.
* @return Authorized key username, NULL if no match was found.
*/
static const char *
auth_pubkey_compare_key(ssh_key key)
{
uint32_t i;
ssh_key pub_key;
const char *username = NULL;
int ret = 0;
/* LOCK */
pthread_mutex_lock(&server_opts.authkey_lock);
for (i = 0; i < server_opts.authkey_count; ++i) {
switch (server_opts.authkeys[i].type) {
case NC_SSH_KEY_UNKNOWN:
ret = ssh_pki_import_pubkey_file(server_opts.authkeys[i].path, &pub_key);
break;
case NC_SSH_KEY_DSA:
ret = ssh_pki_import_pubkey_base64(server_opts.authkeys[i].base64, SSH_KEYTYPE_DSS, &pub_key);
break;
case NC_SSH_KEY_RSA:
ret = ssh_pki_import_pubkey_base64(server_opts.authkeys[i].base64, SSH_KEYTYPE_RSA, &pub_key);
break;
case NC_SSH_KEY_ECDSA:
ret = ssh_pki_import_pubkey_base64(server_opts.authkeys[i].base64, SSH_KEYTYPE_ECDSA, &pub_key);
break;
}
if (ret == SSH_EOF) {
WRN(NULL, "Failed to import a public key of \"%s\" (File access problem).", server_opts.authkeys[i].username);
continue;
} else if (ret == SSH_ERROR) {
WRN(NULL, "Failed to import a public key of \"%s\" (SSH error).", server_opts.authkeys[i].username);
continue;
}
if (!ssh_key_cmp(key, pub_key, SSH_KEY_CMP_PUBLIC)) {
ssh_key_free(pub_key);
break;
}
ssh_key_free(pub_key);
}
if (i < server_opts.authkey_count) {
username = server_opts.authkeys[i].username;
}
/* UNLOCK */
pthread_mutex_unlock(&server_opts.authkey_lock);
return username;
}
static void
nc_sshcb_auth_pubkey(struct nc_session *session, ssh_message msg)
{
const char *username;
int signature_state;
if (server_opts.pubkey_auth_clb) {
if (server_opts.pubkey_auth_clb(session, ssh_message_auth_pubkey(msg), server_opts.pubkey_auth_data)) {
goto fail;
}
} else {
if ((username = auth_pubkey_compare_key(ssh_message_auth_pubkey(msg))) == NULL) {
VRB(session, "User \"%s\" tried to use an unknown (unauthorized) public key.", session->username);
goto fail;
} else if (strcmp(session->username, username)) {
VRB(session, "User \"%s\" is not the username identified with the presented public key.", session->username);
goto fail;
}
}
signature_state = ssh_message_auth_publickey_state(msg);
if (signature_state == SSH_PUBLICKEY_STATE_VALID) {
VRB(session, "User \"%s\" authenticated.", session->username);
session->flags |= NC_SESSION_SSH_AUTHENTICATED;
ssh_message_auth_reply_success(msg, 0);
} else if (signature_state == SSH_PUBLICKEY_STATE_NONE) {
/* accepting only the use of a public key */
ssh_message_auth_reply_pk_ok_simple(msg);
}
return;
fail:
++session->opts.server.ssh_auth_attempts;
VRB(session, "Failed user \"%s\" authentication attempt (#%d).", session->username,
session->opts.server.ssh_auth_attempts);
ssh_message_reply_default(msg);
}
static int
nc_sshcb_channel_open(struct nc_session *session, ssh_message msg)
{
ssh_channel chan;
/* first channel request */
if (!session->ti.libssh.channel) {
if (session->status != NC_STATUS_STARTING) {
ERRINT;
return -1;
}
chan = ssh_message_channel_request_open_reply_accept(msg);
if (!chan) {
ERR(session, "Failed to create a new SSH channel.");
return -1;
}
session->ti.libssh.channel = chan;
/* additional channel request */
} else {
chan = ssh_message_channel_request_open_reply_accept(msg);
if (!chan) {
ERR(session, "Session %u: failed to create a new SSH channel.", session->id);
return -1;
}
/* channel was created and libssh stored it internally in the ssh_session structure, good enough */
}
return 0;
}
static int
nc_sshcb_channel_subsystem(struct nc_session *session, ssh_channel channel, const char *subsystem)
{
struct nc_session *new_session;
if (strcmp(subsystem, "netconf")) {
WRN(session, "Received an unknown subsystem \"%s\" request.", subsystem);
return -1;
}
if (session->ti.libssh.channel == channel) {
/* first channel requested */
if (session->ti.libssh.next || (session->status != NC_STATUS_STARTING)) {
ERRINT;
return -1;
}
if (session->flags & NC_SESSION_SSH_SUBSYS_NETCONF) {
ERR(session, "Subsystem \"netconf\" requested for the second time.");
return -1;
}
session->flags |= NC_SESSION_SSH_SUBSYS_NETCONF;
} else {
/* additional channel subsystem request, new session is ready as far as SSH is concerned */
new_session = nc_new_session(NC_SERVER, 1);
if (!new_session) {
ERRMEM;
return -1;
}
/* insert the new session */
if (!session->ti.libssh.next) {
new_session->ti.libssh.next = session;
} else {
new_session->ti.libssh.next = session->ti.libssh.next;
}
session->ti.libssh.next = new_session;
new_session->status = NC_STATUS_STARTING;
new_session->ti_type = NC_TI_LIBSSH;
new_session->io_lock = session->io_lock;
new_session->ti.libssh.channel = channel;
new_session->ti.libssh.session = session->ti.libssh.session;
new_session->username = strdup(session->username);
new_session->host = strdup(session->host);
new_session->port = session->port;
new_session->ctx = (struct ly_ctx *)session->ctx;
new_session->flags = NC_SESSION_SSH_AUTHENTICATED | NC_SESSION_SSH_SUBSYS_NETCONF | NC_SESSION_SHAREDCTX;
}
return 0;
}
int
nc_sshcb_msg(ssh_session UNUSED(sshsession), ssh_message msg, void *data)
{
const char *str_type, *str_subtype = NULL, *username;
int subtype, type;
struct nc_session *session = (struct nc_session *)data;
type = ssh_message_type(msg);
subtype = ssh_message_subtype(msg);
switch (type) {
case SSH_REQUEST_AUTH:
str_type = "request-auth";
switch (subtype) {
case SSH_AUTH_METHOD_NONE:
str_subtype = "none";
break;
case SSH_AUTH_METHOD_PASSWORD:
str_subtype = "password";
break;
case SSH_AUTH_METHOD_PUBLICKEY:
str_subtype = "publickey";
break;
case SSH_AUTH_METHOD_HOSTBASED:
str_subtype = "hostbased";
break;
case SSH_AUTH_METHOD_INTERACTIVE:
str_subtype = "interactive";
break;
case SSH_AUTH_METHOD_GSSAPI_MIC:
str_subtype = "gssapi-mic";
break;
}
break;
case SSH_REQUEST_CHANNEL_OPEN:
str_type = "request-channel-open";
switch (subtype) {
case SSH_CHANNEL_SESSION:
str_subtype = "session";
break;
case SSH_CHANNEL_DIRECT_TCPIP:
str_subtype = "direct-tcpip";
break;
case SSH_CHANNEL_FORWARDED_TCPIP:
str_subtype = "forwarded-tcpip";
break;
case (int)SSH_CHANNEL_X11:
str_subtype = "channel-x11";
break;
case SSH_CHANNEL_UNKNOWN:
/* fallthrough */
default:
str_subtype = "unknown";
break;
}
break;
case SSH_REQUEST_CHANNEL:
str_type = "request-channel";
switch (subtype) {
case SSH_CHANNEL_REQUEST_PTY:
str_subtype = "pty";
break;
case SSH_CHANNEL_REQUEST_EXEC:
str_subtype = "exec";
break;
case SSH_CHANNEL_REQUEST_SHELL:
str_subtype = "shell";
break;
case SSH_CHANNEL_REQUEST_ENV:
str_subtype = "env";
break;
case SSH_CHANNEL_REQUEST_SUBSYSTEM:
str_subtype = "subsystem";
break;
case SSH_CHANNEL_REQUEST_WINDOW_CHANGE:
str_subtype = "window-change";
break;
case SSH_CHANNEL_REQUEST_X11:
str_subtype = "x11";
break;
case SSH_CHANNEL_REQUEST_UNKNOWN:
/* fallthrough */
default:
str_subtype = "unknown";
break;
}
break;
case SSH_REQUEST_SERVICE:
str_type = "request-service";
str_subtype = ssh_message_service_service(msg);
break;
case SSH_REQUEST_GLOBAL:
str_type = "request-global";
switch (subtype) {
case SSH_GLOBAL_REQUEST_TCPIP_FORWARD:
str_subtype = "tcpip-forward";
break;
case SSH_GLOBAL_REQUEST_CANCEL_TCPIP_FORWARD:
str_subtype = "cancel-tcpip-forward";
break;
case SSH_GLOBAL_REQUEST_UNKNOWN:
/* fallthrough */
default:
str_subtype = "unknown";
break;
}
break;
default:
str_type = "unknown";
str_subtype = "unknown";
break;
}
VRB(session, "Received an SSH message \"%s\" of subtype \"%s\".", str_type, str_subtype);
if (!session || (session->status == NC_STATUS_CLOSING) || (session->status == NC_STATUS_INVALID)) {
/* "valid" situation if, for example, receiving some auth or channel request timeouted,
* but we got it now, during session free */
VRB(session, "SSH message arrived on a %s session, the request will be denied.",
(session && session->status == NC_STATUS_CLOSING ? "closing" : "invalid"));
ssh_message_reply_default(msg);
return 0;
}
session->flags |= NC_SESSION_SSH_NEW_MSG;
/*
* process known messages
*/
if (type == SSH_REQUEST_AUTH) {
if (session->flags & NC_SESSION_SSH_AUTHENTICATED) {
ERR(session, "User \"%s\" authenticated, but requested another authentication.", session->username);
ssh_message_reply_default(msg);
return 0;
}
/* save the username, do not let the client change it */
username = ssh_message_auth_user(msg);
if (!session->username) {
if (!username) {
ERR(session, "Denying an auth request without a username.");
return 1;
}
session->username = strdup(username);
} else if (username) {
if (strcmp(username, session->username)) {
ERR(session, "User \"%s\" changed its username to \"%s\".", session->username, username);
session->status = NC_STATUS_INVALID;
session->term_reason = NC_SESSION_TERM_OTHER;
return 1;
}
}
if (subtype == SSH_AUTH_METHOD_NONE) {
/* libssh will return the supported auth methods */
return 1;
} else if (subtype == SSH_AUTH_METHOD_PASSWORD) {
nc_sshcb_auth_password(session, msg);
return 0;
} else if (subtype == SSH_AUTH_METHOD_PUBLICKEY) {
nc_sshcb_auth_pubkey(session, msg);
return 0;
} else if (subtype == SSH_AUTH_METHOD_INTERACTIVE) {
nc_sshcb_auth_kbdint(session, msg);
return 0;
}
} else if (session->flags & NC_SESSION_SSH_AUTHENTICATED) {
if ((type == SSH_REQUEST_CHANNEL_OPEN) && ((enum ssh_channel_type_e)subtype == SSH_CHANNEL_SESSION)) {
if (nc_sshcb_channel_open(session, msg)) {
ssh_message_reply_default(msg);
}
return 0;
} else if ((type == SSH_REQUEST_CHANNEL) && ((enum ssh_channel_requests_e)subtype == SSH_CHANNEL_REQUEST_SUBSYSTEM)) {
if (nc_sshcb_channel_subsystem(session, ssh_message_channel_request_channel(msg),
ssh_message_channel_request_subsystem(msg))) {
ssh_message_reply_default(msg);
} else {
ssh_message_channel_request_reply_success(msg);
}
return 0;
}
}
/* we did not process it */
return 1;
}
/* ret 1 on success, 0 on timeout, -1 on error */
static int
nc_accept_ssh_session_open_netconf_channel(struct nc_session *session, int timeout)
{
int ret;
struct timespec ts_timeout;
/* message callback is executed twice to give chance for the channel to be
* created if timeout == 0 (it takes 2 messages, channel-open, subsystem-request) */
if (!timeout) {
if (!nc_session_is_connected(session)) {
ERR(session, "Communication socket unexpectedly closed (libssh).");
return -1;
}
ret = ssh_execute_message_callbacks(session->ti.libssh.session);
if (ret != SSH_OK) {
ERR(session, "Failed to receive SSH messages on a session (%s).",
ssh_get_error(session->ti.libssh.session));
return -1;
}
if (!session->ti.libssh.channel) {
return 0;
}
ret = ssh_execute_message_callbacks(session->ti.libssh.session);
if (ret != SSH_OK) {
ERR(session, "Failed to receive SSH messages on a session (%s).",
ssh_get_error(session->ti.libssh.session));
return -1;
}
if (!(session->flags & NC_SESSION_SSH_SUBSYS_NETCONF)) {
/* we did not receive subsystem-request, timeout */
return 0;
}
return 1;
}
if (timeout > -1) {
nc_gettimespec_mono_add(&ts_timeout, timeout);
}
while (1) {
if (!nc_session_is_connected(session)) {
ERR(session, "Communication socket unexpectedly closed (libssh).");
return -1;
}
ret = ssh_execute_message_callbacks(session->ti.libssh.session);
if (ret != SSH_OK) {
ERR(session, "Failed to receive SSH messages on a session (%s).",
ssh_get_error(session->ti.libssh.session));
return -1;
}
if (session->ti.libssh.channel && (session->flags & NC_SESSION_SSH_SUBSYS_NETCONF)) {
return 1;
}
usleep(NC_TIMEOUT_STEP);
if ((timeout > -1) && (nc_difftimespec_mono_cur(&ts_timeout) < 1)) {
/* timeout */
ERR(session, "Failed to start \"netconf\" SSH subsystem for too long, disconnecting.");
break;
}
}
return 0;
}
/**
* @brief Set hostkeys to be used for an SSH bind.
*
* @param[in] sbind SSH bind to use.
* @param[in] hostkeys Array of hostkeys.
* @param[in] hostkey_count Count of @p hostkeys.
* @return 0 on success.
* @return -1 on error.
*/
static int
nc_ssh_bind_add_hostkeys(ssh_bind sbind, char **hostkeys, uint8_t hostkey_count)
{
uint8_t i;
char *privkey_path, *privkey_data;
int ret;
NC_SSH_KEY_TYPE privkey_type;
if (!server_opts.hostkey_clb) {
ERR(NULL, "Callback for retrieving SSH host keys not set.");
return -1;
}
for (i = 0; i < hostkey_count; ++i) {
privkey_path = privkey_data = NULL;
if (server_opts.hostkey_clb(hostkeys[i], server_opts.hostkey_data, &privkey_path, &privkey_data, &privkey_type)) {
ERR(NULL, "Host key callback failed.");
return -1;
}
if (privkey_data) {
privkey_path = base64der_key_to_tmp_file(privkey_data, nc_keytype2str(privkey_type));
if (!privkey_path) {
ERR(NULL, "Temporarily storing a host key into a file failed (%s).", strerror(errno));
free(privkey_data);
return -1;
}
}
ret = ssh_bind_options_set(sbind, SSH_BIND_OPTIONS_HOSTKEY, privkey_path);
/* cleanup */
if (privkey_data && unlink(privkey_path)) {
WRN(NULL, "Removing a temporary host key file \"%s\" failed (%s).", privkey_path, strerror(errno));
}
free(privkey_data);
if (ret != SSH_OK) {
ERR(NULL, "Failed to set hostkey \"%s\" (%s).", hostkeys[i], privkey_path);
}
free(privkey_path);
if (ret != SSH_OK) {
return -1;
}
}
return 0;
}
static int
nc_accept_ssh_session_auth(struct nc_session *session, const struct nc_server_ssh_opts *opts)
{
struct timespec ts_timeout;
ssh_message msg;
int libssh_auth_methods = 0;
/* configure accepted auth methods */
if (opts->auth_methods & NC_SSH_AUTH_PUBLICKEY) {
libssh_auth_methods |= SSH_AUTH_METHOD_PUBLICKEY;
}
if (opts->auth_methods & NC_SSH_AUTH_PASSWORD) {
libssh_auth_methods |= SSH_AUTH_METHOD_PASSWORD;
}
if (opts->auth_methods & NC_SSH_AUTH_INTERACTIVE) {
libssh_auth_methods |= SSH_AUTH_METHOD_INTERACTIVE;
}
ssh_set_auth_methods(session->ti.libssh.session, libssh_auth_methods);
/* authenticate */
if (opts->auth_timeout) {
nc_gettimespec_mono_add(&ts_timeout, opts->auth_timeout * 1000);
}
while (1) {
if (!nc_session_is_connected(session)) {
ERR(session, "Communication SSH socket unexpectedly closed.");
return -1;
}
msg = ssh_message_get(session->ti.libssh.session);
if (msg) {
if (nc_sshcb_msg(session->ti.libssh.session, msg, (void *) session)) {
ssh_message_reply_default(msg);
}
ssh_message_free(msg);
}
if (session->flags & NC_SESSION_SSH_AUTHENTICATED) {
break;
}
if (session->opts.server.ssh_auth_attempts >= opts->auth_attempts) {
ERR(session, "Too many failed authentication attempts of user \"%s\".", session->username);
return -1;
}
usleep(NC_TIMEOUT_STEP);
if ((opts->auth_timeout) && (nc_difftimespec_mono_cur(&ts_timeout) < 1)) {
/* timeout */
break;
}
}
if (!(session->flags & NC_SESSION_SSH_AUTHENTICATED)) {
/* timeout */
if (session->username) {
ERR(session, "User \"%s\" failed to authenticate for too long, disconnecting.", session->username);
} else {
ERR(session, "User failed to authenticate for too long, disconnecting.");
}
return 0;
}
return 1;
}
int
nc_accept_ssh_session(struct nc_session *session, int sock, int timeout)
{
ssh_bind sbind = NULL;
struct nc_server_ssh_opts *opts;
int rc = 1, r;
struct timespec ts_timeout;
opts = session->data;
/* other transport-specific data */
session->ti_type = NC_TI_LIBSSH;
session->ti.libssh.session = ssh_new();
if (!session->ti.libssh.session) {
ERR(NULL, "Failed to initialize a new SSH session.");
rc = -1;
goto cleanup;
}
sbind = ssh_bind_new();
if (!sbind) {
ERR(session, "Failed to create an SSH bind.");
rc = -1;
goto cleanup;
}
/* configure host keys */
if (nc_ssh_bind_add_hostkeys(sbind, opts->hostkeys, opts->hostkey_count)) {
rc = -1;
goto cleanup;
}
/* accept new connection on the bind */
if (ssh_bind_accept_fd(sbind, session->ti.libssh.session, sock) == SSH_ERROR) {
ERR(session, "SSH failed to accept a new connection (%s).", ssh_get_error(sbind));
rc = -1;
goto cleanup;
}
sock = -1;
ssh_set_blocking(session->ti.libssh.session, 0);
if (timeout > -1) {
nc_gettimespec_mono_add(&ts_timeout, timeout);
}
while ((r = ssh_handle_key_exchange(session->ti.libssh.session)) == SSH_AGAIN) {
/* this tends to take longer */
usleep(NC_TIMEOUT_STEP * 20);
if ((timeout > -1) && (nc_difftimespec_mono_cur(&ts_timeout) < 1)) {
break;
}
}
if (r == SSH_AGAIN) {
ERR(session, "SSH key exchange timeout.");
rc = 0;
goto cleanup;
} else if (r != SSH_OK) {
ERR(session, "SSH key exchange error (%s).", ssh_get_error(session->ti.libssh.session));
rc = -1;
goto cleanup;
}
/* authenticate */
if ((rc = nc_accept_ssh_session_auth(session, opts)) != 1) {
goto cleanup;
}
/* set the message callback after a successful authentication */
ssh_set_message_callback(session->ti.libssh.session, nc_sshcb_msg, session);
/* remember that this session was just set as nc_sshcb_msg() parameter */
session->flags |= NC_SESSION_SSH_MSG_CB;
/* open channel and request 'netconf' subsystem */
if ((rc = nc_accept_ssh_session_open_netconf_channel(session, timeout)) != 1) {
goto cleanup;
}
/* all SSH messages were processed */
session->flags &= ~NC_SESSION_SSH_NEW_MSG;
cleanup:
if (sock > -1) {
close(sock);
}
ssh_bind_free(sbind);
return rc;
}
API NC_MSG_TYPE
nc_session_accept_ssh_channel(struct nc_session *orig_session, struct nc_session **session)
{
NC_MSG_TYPE msgtype;
struct nc_session *new_session = NULL;
struct timespec ts_cur;
if (!orig_session) {
ERRARG("orig_session");
return NC_MSG_ERROR;
} else if (!session) {
ERRARG("session");
return NC_MSG_ERROR;
}
if ((orig_session->status == NC_STATUS_RUNNING) && (orig_session->ti_type == NC_TI_LIBSSH) &&
orig_session->ti.libssh.next) {
for (new_session = orig_session->ti.libssh.next;
new_session != orig_session;
new_session = new_session->ti.libssh.next) {
if ((new_session->status == NC_STATUS_STARTING) && new_session->ti.libssh.channel &&
(new_session->flags & NC_SESSION_SSH_SUBSYS_NETCONF)) {
/* we found our session */
break;
}
}
if (new_session == orig_session) {
new_session = NULL;
}
}
if (!new_session) {
ERR(orig_session, "Session does not have a NETCONF SSH channel ready.");
return NC_MSG_ERROR;
}
/* assign new SID atomically */
new_session->id = ATOMIC_INC_RELAXED(server_opts.new_session_id);
/* NETCONF handshake */
msgtype = nc_handshake_io(new_session);
if (msgtype != NC_MSG_HELLO) {
return msgtype;
}
nc_gettimespec_real_add(&ts_cur, 0);
new_session->opts.server.session_start = ts_cur.tv_sec;
nc_gettimespec_mono_add(&ts_cur, 0);
new_session->opts.server.last_rpc = ts_cur.tv_sec;
new_session->status = NC_STATUS_RUNNING;
*session = new_session;
return msgtype;
}
API NC_MSG_TYPE
nc_ps_accept_ssh_channel(struct nc_pollsession *ps, struct nc_session **session)
{
uint8_t q_id;
NC_MSG_TYPE msgtype;
struct nc_session *new_session = NULL, *cur_session;
struct timespec ts_cur;
uint16_t i;
if (!ps) {
ERRARG("ps");
return NC_MSG_ERROR;
} else if (!session) {
ERRARG("session");
return NC_MSG_ERROR;
}
/* LOCK */
if (nc_ps_lock(ps, &q_id, __func__)) {
return NC_MSG_ERROR;
}
for (i = 0; i < ps->session_count; ++i) {
cur_session = ps->sessions[i]->session;
if ((cur_session->status == NC_STATUS_RUNNING) && (cur_session->ti_type == NC_TI_LIBSSH) &&
cur_session->ti.libssh.next) {
/* an SSH session with more channels */
for (new_session = cur_session->ti.libssh.next;
new_session != cur_session;
new_session = new_session->ti.libssh.next) {
if ((new_session->status == NC_STATUS_STARTING) && new_session->ti.libssh.channel &&
(new_session->flags & NC_SESSION_SSH_SUBSYS_NETCONF)) {
/* we found our session */
break;
}
}
if (new_session != cur_session) {
break;
}
new_session = NULL;
}
}
/* UNLOCK */
nc_ps_unlock(ps, q_id, __func__);
if (!new_session) {
ERR(NULL, "No session with a NETCONF SSH channel ready was found.");
return NC_MSG_ERROR;
}
/* assign new SID atomically */
new_session->id = ATOMIC_INC_RELAXED(server_opts.new_session_id);
/* NETCONF handshake */
msgtype = nc_handshake_io(new_session);
if (msgtype != NC_MSG_HELLO) {
return msgtype;
}
nc_gettimespec_real_add(&ts_cur, 0);
new_session->opts.server.session_start = ts_cur.tv_sec;
nc_gettimespec_mono_add(&ts_cur, 0);
new_session->opts.server.last_rpc = ts_cur.tv_sec;
new_session->status = NC_STATUS_RUNNING;
*session = new_session;
return msgtype;
}