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/*
Copyright (c) 2019, 2025, Oracle and/or its affiliates.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.
This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License, version 2.0, for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "sql-common/net_ns.h"
#ifdef HAVE_SETNS
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <assert.h>
#include <sched.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <map>
#include <mutex>
#include <unordered_map>
#include "my_sys.h"
#include "mysql/components/services/log_builtins.h"
#include "mysqld_error.h"
#ifdef MYSQL_SERVER
using namespaces_registry_t = std::map<std::string, int>;
static namespaces_registry_t opened_namespaces;
/*
This mutex is to protect access to the opened_namespaces object.
*/
static std::mutex lock;
#else
/*
fd for opened file corresponding to a network namespace.
Since the mysql program and other similar programs use only one connection
to a server it is ok to store a file descriptor for opened network namespace
in primitive variable. Also it is worth to note that the mysql program
and similar work with connection to a server in single threaded mode so
data protection by mutex not required.
*/
static int ns_fd = -1;
#endif
static int original_ns_fd = -1;
/**
Open a network namespace specified by function argument.
@param network_namespace a name of the network namespace to open
@param[out] fd file descriptor corresponding to
the opened network namespace
@return false on success, true on failure
*/
static bool open_network_namespace(const std::string &network_namespace,
int *fd) {
#ifdef MYSQL_SERVER
std::lock_guard<std::mutex> lck_guard(lock);
auto iter = opened_namespaces.find(network_namespace);
if (iter != opened_namespaces.end()) {
*fd = iter->second;
return false;
}
#endif
char path_to_ns_file[PATH_MAX];
int requested_len = snprintf(path_to_ns_file, sizeof(path_to_ns_file),
"/var/run/netns/%s", network_namespace.c_str());
if (requested_len + 1 > PATH_MAX) {
#ifdef MYSQL_SERVER
LogErr(ERROR_LEVEL, ER_NETWORK_NAMESPACE_FILE_PATH_TOO_LONG, requested_len,
PATH_MAX);
#endif
return true;
}
*fd = open(path_to_ns_file, O_RDONLY);
if (*fd == -1) {
#ifdef MYSQL_SERVER
if (errno == ENOENT)
LogErr(ERROR_LEVEL, ER_UNKNOWN_NETWORK_NAMESPACE,
network_namespace.c_str());
else {
char errbuf[PATH_MAX];
LogErr(ERROR_LEVEL, ER_SERVER_CANT_OPEN_FILE, path_to_ns_file, errno,
my_strerror(errbuf, sizeof(errbuf), errno));
}
#endif
return true;
}
#ifdef MYSQL_SERVER
opened_namespaces.insert(std::make_pair(network_namespace, *fd));
#else
ns_fd = *fd;
#endif
return false;
}
/**
Remember a file descriptor corresponding to the current
active network namespace.
@param[out] orig_ns_fd file descriptor corresponding
to a network namespace used to be active before
@return false on success, true on failure
*/
static bool save_original_network_namespace(int *orig_ns_fd) {
static const char *path_to_current_ns_file = "/proc/self/ns/net";
int fd = open(path_to_current_ns_file, O_RDONLY);
if (fd == -1) {
#ifdef MYSQL_SERVER
char errbuf[MYSYS_STRERROR_SIZE];
LogErr(ERROR_LEVEL, ER_SERVER_CANT_OPEN_FILE, path_to_current_ns_file,
errno, my_strerror(errbuf, sizeof(errbuf), errno));
#endif
return true;
}
*orig_ns_fd = fd;
return false;
}
bool set_network_namespace(const std::string &network_namespace) {
int fd;
if (original_ns_fd == -1 && save_original_network_namespace(&original_ns_fd))
return true;
if (open_network_namespace(network_namespace, &fd)) return true;
if (setns(fd, CLONE_NEWNET) != 0) {
#ifdef MYSQL_SERVER
char errbuf[MYSYS_STRERROR_SIZE];
LogErr(ERROR_LEVEL, ER_SETNS_FAILED,
my_strerror(errbuf, sizeof(errbuf), errno));
#endif
close(fd);
return true;
}
return false;
}
bool restore_original_network_namespace() {
assert(original_ns_fd != -1);
if (setns(original_ns_fd, CLONE_NEWNET) != 0) {
#ifdef MYSQL_SERVER
char errbuf[MYSYS_STRERROR_SIZE];
LogErr(ERROR_LEVEL, ER_SETNS_FAILED,
my_strerror(errbuf, sizeof(errbuf), errno));
#endif
return true;
}
return false;
}
void release_network_namespace_resources() {
#ifdef MYSQL_SERVER
std::lock_guard<std::mutex> lck_guard(lock);
for (const auto &element : opened_namespaces) {
(void)close(element.second);
}
opened_namespaces.clear();
#else
if (ns_fd > -1) {
close(ns_fd);
ns_fd = -1;
}
#endif
if (original_ns_fd > -1) {
close(original_ns_fd);
original_ns_fd = -1;
}
}
#endif
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