blob: 0881c5a6f89cbd8efaa130850835e1630f66b4d5 [file] [log] [blame]
/**
* \file session_server_ssh.c
* \author Michal Vasko <mvasko@cesnet.cz>
* \brief libnetconf2 SSH server session manipulation functions
*
* Copyright (c) 2017 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
#define _POSIX_SOURCE
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <pwd.h>
#include <shadow.h>
#include <crypt.h>
#include <errno.h>
#include "session_server.h"
#include "session_server_ch.h"
#include "libnetconf.h"
extern struct nc_server_opts server_opts;
static char *
base64der_key_to_tmp_file(const char *in, int rsa)
{
char path[12] = "/tmp/XXXXXX";
int fd, written;
mode_t umode;
FILE *file;
if (in == NULL) {
return NULL;
}
umode = umask(0600);
fd = mkstemp(path);
umask(umode);
if (fd == -1) {
return NULL;
}
file = fdopen(fd, "r");
if (!file) {
close(fd);
return NULL;
}
/* write the key into the file */
written = fwrite("-----BEGIN ", 1, 11, file);
written += fwrite((rsa ? "RSA" : "DSA"), 1, 3, 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((rsa ? "RSA" : "DSA"), 1, 3, file);
written += fwrite(" PRIVATE KEY-----", 1, 17, file);
fclose(file);
if ((unsigned)written != 62 + strlen(in)) {
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] = lydict_insert(server_opts.ctx, name, 0);
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 int
nc_server_ssh_ch_client_add_hostkey(const char *client_name, const char *name, int16_t idx)
{
int ret;
struct nc_ch_client *client;
/* LOCK */
client = nc_server_ch_client_lock(client_name, NC_TI_LIBSSH, NULL);
if (!client) {
return -1;
}
ret = nc_server_ssh_add_hostkey(name, idx, client->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, int *privkey_data_rsa),
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) {
lydict_remove(server_opts.ctx, 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;
lydict_remove(server_opts.ctx, 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_del_hostkey(const char *client_name, const char *name, int16_t idx)
{
int ret;
struct nc_ch_client *client;
/* LOCK */
client = nc_server_ch_client_lock(client_name, NC_TI_LIBSSH, NULL);
if (!client) {
return -1;
}
ret = nc_server_ssh_del_hostkey(name, idx, client->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;
const 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_mov_hostkey(const char *client_name, const char *key_mov, const char *key_after)
{
int ret;
struct nc_ch_client *client;
/* LOCK */
client = nc_server_ch_client_lock(client_name, NC_TI_LIBSSH, NULL);
if (!client) {
return -1;
}
ret = nc_server_ssh_mov_hostkey(key_mov, key_after, client->opts.ssh);
/* UNLOCK */
nc_server_ch_client_unlock(client);
return ret;
}
static int
nc_server_ssh_mod_hostkey(const char *name, const char *new_name, struct nc_server_ssh_opts *opts)
{
uint8_t i;
if (!name) {
ERRARG("name");
return -1;
} else if (!new_name) {
ERRARG("new_name");
return -1;
}
for (i = 0; i < opts->hostkey_count; ++i) {
if (!strcmp(opts->hostkeys[i], name)) {
lydict_remove(server_opts.ctx, opts->hostkeys[i]);
opts->hostkeys[i] = lydict_insert(server_opts.ctx, new_name, 0);
return 0;
}
}
ERRARG("name");
return -1;
}
API int
nc_server_ssh_endpt_mod_hostkey(const char *endpt_name, const char *name, const char *new_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 = nc_server_ssh_mov_hostkey(name, new_name, endpt->opts.ssh);
/* UNLOCK */
pthread_rwlock_unlock(&server_opts.endpt_lock);
return ret;
}
API int
nc_server_ssh_ch_client_mod_hostkey(const char *client_name, const char *name, const char *new_name)
{
int ret;
struct nc_ch_client *client;
/* LOCK */
client = nc_server_ch_client_lock(client_name, NC_TI_LIBSSH, NULL);
if (!client) {
return -1;
}
ret = nc_server_ssh_mod_hostkey(name, new_name, client->opts.ssh);
/* UNLOCK */
nc_server_ch_client_unlock(client);
return ret;
}
static int
nc_server_ssh_set_banner(const char *banner, struct nc_server_ssh_opts *opts)
{
if (!banner) {
ERRARG("banner");
return -1;
}
if (opts->banner) {
lydict_remove(server_opts.ctx, opts->banner);
}
opts->banner = lydict_insert(server_opts.ctx, banner, 0);
return 0;
}
API int
nc_server_ssh_endpt_set_banner(const char *endpt_name, const char *banner)
{
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_banner(banner, endpt->opts.ssh);
/* UNLOCK */
pthread_rwlock_unlock(&server_opts.endpt_lock);
return ret;
}
API int
nc_server_ssh_ch_client_set_banner(const char *client_name, const char *banner)
{
int ret;
struct nc_ch_client *client;
/* LOCK */
client = nc_server_ch_client_lock(client_name, NC_TI_LIBSSH, NULL);
if (!client) {
return -1;
}
ret = nc_server_ssh_set_banner(banner, client->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_PUBLICKEY) && !(auth_methods & NC_SSH_AUTH_PASSWORD)
&& !(auth_methods & NC_SSH_AUTH_INTERACTIVE)) {
ERRARG("auth_methods");
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_set_auth_methods(const char *client_name, int auth_methods)
{
int ret;
struct nc_ch_client *client;
/* LOCK */
client = nc_server_ch_client_lock(client_name, NC_TI_LIBSSH, NULL);
if (!client) {
return -1;
}
ret = nc_server_ssh_set_auth_methods(auth_methods, client->opts.ssh);
/* 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_set_ch_client_auth_attempts(const char *client_name, uint16_t auth_attempts)
{
int ret;
struct nc_ch_client *client;
/* LOCK */
client = nc_server_ch_client_lock(client_name, NC_TI_LIBSSH, NULL);
if (!client) {
return -1;
}
ret = nc_server_ssh_set_auth_attempts(auth_attempts, client->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_set_auth_timeout(const char *client_name, uint16_t auth_timeout)
{
int ret;
struct nc_ch_client *client;
/* LOCK */
client = nc_server_ch_client_lock(client_name, NC_TI_LIBSSH, NULL);
if (!client) {
return -1;
}
ret = nc_server_ssh_set_auth_timeout(auth_timeout, client->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)
{
/* 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;
return -1;
}
server_opts.authkeys[server_opts.authkey_count - 1].path = lydict_insert(server_opts.ctx, pubkey_path, 0);
server_opts.authkeys[server_opts.authkey_count - 1].base64 = lydict_insert(server_opts.ctx, pubkey_base64, 0);
server_opts.authkeys[server_opts.authkey_count - 1].type = type;
server_opts.authkeys[server_opts.authkey_count - 1].username = lydict_insert(server_opts.ctx, username, 0);
/* UNLOCK */
pthread_mutex_unlock(&server_opts.authkey_lock);
return 0;
}
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) {
lydict_remove(server_opts.ctx, server_opts.authkeys[i].path);
lydict_remove(server_opts.ctx, server_opts.authkeys[i].base64);
lydict_remove(server_opts.ctx, 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))) {
lydict_remove(server_opts.ctx, server_opts.authkeys[i].path);
lydict_remove(server_opts.ctx, server_opts.authkeys[i].base64);
lydict_remove(server_opts.ctx, 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);
if (opts->banner) {
lydict_remove(server_opts.ctx, opts->banner);
opts->banner = NULL;
}
}
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[256];
getpwnam_r(username, &pwd_buf, buf, 256, &pwd);
if (!pwd) {
VRB("User \"%s\" not found locally.", username);
return NULL;
}
if (!strcmp(pwd->pw_passwd, "x")) {
getspnam_r(username, &spwd_buf, buf, 256, &spwd);
if (!spwd) {
VRB("Failed to retrieve the shadow entry for \"%s\".", username);
return NULL;
}
pass_hash = spwd->sp_pwdp;
} else {
pass_hash = pwd->pw_passwd;
}
if (!pass_hash) {
ERR("No password could be retrieved for \"%s\".", username);
return NULL;
}
/* check the hash structure for special meaning */
if (!strcmp(pass_hash, "*") || !strcmp(pass_hash, "!")) {
VRB("User \"%s\" is not allowed to authenticate using a password.", username);
return NULL;
}
if (!strcmp(pass_hash, "*NP*")) {
VRB("Retrieving password for \"%s\" from a NIS+ server not supported.", username);
return NULL;
}
return strdup(pass_hash);
}
static int
auth_password_compare_pwd(const char *pass_hash, const char *pass_clear)
{
char *new_pass_hash;
struct crypt_data cdata;
if (!pass_hash[0]) {
if (!pass_clear[0]) {
WRN("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;
}
}
cdata.initialized = 0;
new_pass_hash = crypt_r(pass_clear, pass_hash, &cdata);
return strcmp(new_pass_hash, pass_hash);
}
static void
nc_sshcb_auth_password(struct nc_session *session, ssh_message msg)
{
char *pass_hash;
pass_hash = auth_password_get_pwd_hash(session->username);
if (pass_hash && !auth_password_compare_pwd(pass_hash, ssh_message_auth_password(msg))) {
VRB("User \"%s\" authenticated.", session->username);
ssh_message_auth_reply_success(msg, 0);
session->flags |= NC_SESSION_SSH_AUTHENTICATED;
free(pass_hash);
return;
}
free(pass_hash);
++session->opts.server.ssh_auth_attempts;
VRB("Failed user \"%s\" authentication attempt (#%d).", session->username, session->opts.server.ssh_auth_attempts);
ssh_message_reply_default(msg);
}
static void
nc_sshcb_auth_kbdint(struct nc_session *session, ssh_message msg)
{
char *pass_hash;
if (!ssh_message_auth_kbdint_is_response(msg)) {
const char *prompts[] = {"Password: "};
char echo[] = {0};
ssh_message_auth_interactive_request(msg, "Interactive SSH Authentication", "Type your password:", 1, prompts, echo);
} else {
if (ssh_userauth_kbdint_getnanswers(session->ti.libssh.session) != 1) {
ssh_message_reply_default(msg);
return;
}
pass_hash = auth_password_get_pwd_hash(session->username);
if (!pass_hash) {
ssh_message_reply_default(msg);
return;
}
if (!auth_password_compare_pwd(pass_hash, ssh_userauth_kbdint_getanswer(session->ti.libssh.session, 0))) {
VRB("User \"%s\" authenticated.", session->username);
session->flags |= NC_SESSION_SSH_AUTHENTICATED;
ssh_message_auth_reply_success(msg, 0);
} else {
++session->opts.server.ssh_auth_attempts;
VRB("Failed user \"%s\" authentication attempt (#%d).", session->username, session->opts.server.ssh_auth_attempts);
ssh_message_reply_default(msg);
}
free(pass_hash);
}
}
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("Failed to import a public key of \"%s\" (File access problem).", server_opts.authkeys[i].username);
continue;
} else if (ret == SSH_ERROR) {
WRN("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 ((username = auth_pubkey_compare_key(ssh_message_auth_pubkey(msg))) == NULL) {
VRB("User \"%s\" tried to use an unknown (unauthorized) public key.", session->username);
goto fail;
} else if (strcmp(session->username, username)) {
VRB("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("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("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("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 %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("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 %u: subsystem \"netconf\" requested for the second time.", session->id);
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(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->side = NC_SERVER;
new_session->ti_type = NC_TI_LIBSSH;
new_session->ti_lock = session->ti_lock;
new_session->ti_cond = session->ti_cond;
new_session->ti_inuse = session->ti_inuse;
new_session->ti.libssh.channel = channel;
new_session->ti.libssh.session = session->ti.libssh.session;
new_session->username = lydict_insert(server_opts.ctx, session->username, 0);
new_session->host = lydict_insert(server_opts.ctx, session->host, 0);
new_session->port = session->port;
new_session->ctx = server_opts.ctx;
new_session->flags = NC_SESSION_SSH_AUTHENTICATED | NC_SESSION_SSH_SUBSYS_NETCONF | NC_SESSION_SHAREDCTX
| (session->flags & NC_SESSION_CALLHOME ? NC_SESSION_CALLHOME : 0);
}
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("Received an SSH message \"%s\" of subtype \"%s\".", str_type, str_subtype);
if ((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("SSH message arrived on a %s session, the request will be denied.",
(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("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("Denying an auth request without a username.");
return 1;
}
session->username = lydict_insert(server_opts.ctx, username, 0);
} else if (username) {
if (strcmp(username, session->username)) {
ERR("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_open_netconf_channel(struct nc_session *session, int timeout)
{
int ret;
struct timespec ts_timeout, ts_cur;
/* 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("Communication socket unexpectedly closed (libssh).");
return -1;
}
ret = nc_session_lock(session, timeout, __func__);
if (ret != 1) {
return ret;
}
ret = ssh_execute_message_callbacks(session->ti.libssh.session);
if (ret != SSH_OK) {
ERR("Failed to receive SSH messages on a session (%s).",
ssh_get_error(session->ti.libssh.session));
nc_session_unlock(session, timeout, __func__);
return -1;
}
if (!session->ti.libssh.channel) {
/* we did not receive channel-open, timeout */
nc_session_unlock(session, timeout, __func__);
return 0;
}
ret = ssh_execute_message_callbacks(session->ti.libssh.session);
nc_session_unlock(session, timeout, __func__);
if (ret != SSH_OK) {
ERR("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(&ts_timeout);
nc_addtimespec(&ts_timeout, timeout);
}
while (1) {
if (!nc_session_is_connected(session)) {
ERR("Communication socket unexpectedly closed (libssh).");
return -1;
}
ret = nc_session_lock(session, timeout, __func__);
if (ret != 1) {
return ret;
}
ret = ssh_execute_message_callbacks(session->ti.libssh.session);
nc_session_unlock(session, timeout, __func__);
if (ret != SSH_OK) {
ERR("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_gettimespec(&ts_cur);
if (nc_difftimespec(&ts_cur, &ts_timeout) < 1) {
/* timeout */
ERR("Failed to start \"netconf\" SSH subsystem for too long, disconnecting.");
break;
}
}
}
return 0;
}
static int
nc_ssh_bind_add_hostkeys(ssh_bind sbind, const char **hostkeys, uint8_t hostkey_count)
{
uint8_t i;
char *privkey_path, *privkey_data;
int privkey_data_rsa, ret;
if (!server_opts.hostkey_clb) {
ERR("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_data_rsa)) {
ERR("Host key callback failed.");
return -1;
}
if (privkey_data) {
privkey_path = base64der_key_to_tmp_file(privkey_data, privkey_data_rsa);
if (!privkey_path) {
ERR("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("Removing a temporary host key file \"%s\" failed (%s).", privkey_path, strerror(errno));
}
free(privkey_data);
if (ret != SSH_OK) {
ERR("Failed to set hostkey \"%s\" (%s).", hostkeys[i], privkey_path);
}
free(privkey_path);
if (ret != SSH_OK) {
return -1;
}
}
return 0;
}
int
nc_accept_ssh_session(struct nc_session *session, int sock, int timeout)
{
ssh_bind sbind;
struct nc_server_ssh_opts *opts;
int libssh_auth_methods = 0, ret;
struct timespec ts_timeout, ts_cur;
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("Failed to initialize a new SSH session.");
close(sock);
return -1;
}
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);
sbind = ssh_bind_new();
if (!sbind) {
ERR("Failed to create an SSH bind.");
close(sock);
return -1;
}
if (nc_ssh_bind_add_hostkeys(sbind, opts->hostkeys, opts->hostkey_count)) {
close(sock);
ssh_bind_free(sbind);
return -1;
}
if (opts->banner) {
ssh_bind_options_set(sbind, SSH_BIND_OPTIONS_BANNER, opts->banner);
}
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;
if (ssh_bind_accept_fd(sbind, session->ti.libssh.session, sock) == SSH_ERROR) {
ERR("SSH failed to accept a new connection (%s).", ssh_get_error(sbind));
close(sock);
ssh_bind_free(sbind);
return -1;
}
ssh_bind_free(sbind);
ssh_set_blocking(session->ti.libssh.session, 0);
if (timeout > -1) {
nc_gettimespec(&ts_timeout);
nc_addtimespec(&ts_timeout, timeout);
}
while ((ret = ssh_handle_key_exchange(session->ti.libssh.session)) == SSH_AGAIN) {
/* this tends to take longer */
usleep(NC_TIMEOUT_STEP * 20);
if (timeout > -1) {
nc_gettimespec(&ts_cur);
if (nc_difftimespec(&ts_cur, &ts_timeout) < 1) {
break;
}
}
}
if (ret == SSH_AGAIN) {
ERR("SSH key exchange timeout.");
return 0;
} else if (ret != SSH_OK) {
ERR("SSH key exchange error (%s).", ssh_get_error(session->ti.libssh.session));
return -1;
}
/* authenticate */
if (opts->auth_timeout) {
nc_gettimespec(&ts_timeout);
nc_addtimespec(&ts_timeout, opts->auth_timeout * 1000);
}
while (1) {
if (!nc_session_is_connected(session)) {
ERR("Communication SSH socket unexpectedly closed.");
return -1;
}
if (ssh_execute_message_callbacks(session->ti.libssh.session) != SSH_OK) {
ERR("Failed to receive SSH messages on a session (%s).",
ssh_get_error(session->ti.libssh.session));
return -1;
}
if (session->flags & NC_SESSION_SSH_AUTHENTICATED) {
break;
}
if (session->opts.server.ssh_auth_attempts >= opts->auth_attempts) {
ERR("Too many failed authentication attempts of user \"%s\".", session->username);
return -1;
}
usleep(NC_TIMEOUT_STEP);
if (opts->auth_timeout) {
nc_gettimespec(&ts_cur);
if (nc_difftimespec(&ts_cur, &ts_timeout) < 1) {
/* timeout */
break;
}
}
}
if (!(session->flags & NC_SESSION_SSH_AUTHENTICATED)) {
/* timeout */
if (session->username) {
ERR("User \"%s\" failed to authenticate for too long, disconnecting.", session->username);
} else {
ERR("User failed to authenticate for too long, disconnecting.");
}
return 0;
}
/* open channel */
ret = nc_open_netconf_channel(session, timeout);
if (ret < 1) {
return ret;
}
session->flags &= ~NC_SESSION_SSH_NEW_MSG;
return 1;
}
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;
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("Session does not have a NETCONF SSH channel ready.");
return NC_MSG_ERROR;
}
/* assign new SID atomically */
pthread_spin_lock(&server_opts.sid_lock);
new_session->id = server_opts.new_session_id++;
pthread_spin_unlock(&server_opts.sid_lock);
/* NETCONF handshake */
msgtype = nc_handshake(new_session);
if (msgtype != NC_MSG_HELLO) {
return msgtype;
}
new_session->opts.server.session_start = new_session->opts.server.last_rpc = time(NULL);
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;
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("No session with a NETCONF SSH channel ready was found.");
return NC_MSG_ERROR;
}
/* assign new SID atomically */
pthread_spin_lock(&server_opts.sid_lock);
new_session->id = server_opts.new_session_id++;
pthread_spin_unlock(&server_opts.sid_lock);
/* NETCONF handshake */
msgtype = nc_handshake(new_session);
if (msgtype != NC_MSG_HELLO) {
return msgtype;
}
new_session->opts.server.session_start = new_session->opts.server.last_rpc = time(NULL);
new_session->status = NC_STATUS_RUNNING;
*session = new_session;
return msgtype;
}