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daemon: '--listen' can be passed several times, can specify TCP endpoints.

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* nix/nix-daemon/guix-daemon.cc (DEFAULT_GUIX_PORT): New macro.
(listen_options): New variable.
(parse_opt): Push back '--listen' options to LISTEN_OPTIONS.
(open_unix_domain_socket, open_inet_socket)
(listening_sockets): New functions.
(main): Use it.  Pass SOCKETS to 'run'.
* nix/nix-daemon/nix-daemon.cc (matchUser): Remove.
(SD_LISTEN_FDS_START): Remove.
(acceptConnection): New function.
(daemonLoop): Rewrite to take a vector of file descriptors, to select(2)
on them, and to call 'acceptConnection'.
(run): Change to take a vector of file descriptors.
* tests/guix-daemon.sh: Add test.
This commit is contained in:
Ludovic Courtès 2017-06-19 17:39:24 +02:00 committed by Ludovic Courtès
parent 5df1395a8d
commit 1071f781d9
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4 changed files with 322 additions and 170 deletions
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55
doc/guix.texi
View file

@ -1258,12 +1258,47 @@ Assume @var{system} as the current system type. By default it is the
architecture/kernel pair found at configure time, such as
@code{x86_64-linux}.
@item --listen=@var{socket}
Listen for connections on @var{socket}, the file name of a Unix-domain
socket. The default socket is
@file{@var{localstatedir}/daemon-socket/socket}. This option is only
useful in exceptional circumstances, such as if you need to run several
daemons on the same machine.
@item --listen=@var{endpoint}
Listen for connections on @var{endpoint}. @var{endpoint} is interpreted
as the file name of a Unix-domain socket if it starts with
@code{/} (slash sign). Otherwise, @var{endpoint} is interpreted as a
host name or host name and port to listen to. Here are a few examples:
@table @code
@item --listen=/gnu/var/daemon
Listen for connections on the @file{/gnu/var/daemon} Unix-domain socket,
creating it if needed.
@item --listen=localhost
@cindex daemon, remote access
@cindex remote access to the daemon
@cindex daemon, cluster setup
@cindex clusters, daemon setup
Listen for TCP connections on the network interface corresponding to
@code{localhost}, on port 44146.
@item --listen=128.0.0.42:1234
Listen for TCP connections on the network interface corresponding to
@code{128.0.0.42}, on port 1234.
@end table
This option can be repeated multiple times, in which case
@command{guix-daemon} accepts connections on all the specified
endpoints. Users can tell client commands what endpoint to connect to
by setting the @code{GUIX_DAEMON_SOCKET} environment variable
(@pxref{The Store, @code{GUIX_DAEMON_SOCKET}}).
@quotation Note
The daemon protocol is @emph{unauthenticated and unencrypted}. Using
@code{--listen=@var{host}} is suitable on local networks, such as
clusters, where only trusted nodes may connect to the build daemon. In
other cases where remote access to the daemon is needed, we recommend
using Unix-domain sockets along with SSH.
@end quotation
When @code{--listen} is omitted, @command{guix-daemon} listens for
connections on the Unix-domain socket located at
@file{@var{localstatedir}/daemon-socket/socket}.
@end table
@ -3769,6 +3804,10 @@ These are for Unix-domain sockets.
@file{/var/guix/daemon-socket/socket}.
@item guix
@cindex daemon, remote access
@cindex remote access to the daemon
@cindex daemon, cluster setup
@cindex clusters, daemon setup
These URIs denote connections over TCP/IP, without encryption nor
authentication of the remote host. The URI must specify the host name
and optionally a port number (by default port 44146 is used):
@ -3781,6 +3820,10 @@ This setup is suitable on local networks, such as clusters, where only
trusted nodes may connect to the build daemon at
@code{master.guix.example.org}.
The @code{--listen} option of @command{guix-daemon} can be used to
instruct it to listen for TCP connections (@pxref{Invoking guix-daemon,
@code{--listen}}).
@item ssh
@cindex SSH access to build daemons
These URIs allow you to connect to a remote daemon over

152
nix/nix-daemon/guix-daemon.cc
View file

@ -1,5 +1,6 @@
/* GNU Guix --- Functional package management for GNU
Copyright (C) 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
Copyright (C) 2006, 2010, 2012, 2014 Eelco Dolstra <e.dolstra@tudelft.nl>
This file is part of GNU Guix.
@ -30,8 +31,12 @@
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netdb.h>
#include <strings.h>
#include <exception>
#include <iostream>
#include <libintl.h>
#include <locale.h>
@ -43,7 +48,7 @@ char **argvSaved;
using namespace nix;
/* Entry point in `nix-daemon.cc'. */
extern void run (Strings args);
extern void run (const std::vector<int> &);
/* Command-line options. */
@ -149,6 +154,12 @@ to live outputs") },
};
/* Default port for '--listen' on TCP/IP. */
#define DEFAULT_GUIX_PORT "44146"
/* List of '--listen' options. */
static std::list<std::string> listen_options;
/* Convert ARG to a Boolean value, or throw an error if it does not denote a
Boolean. */
static bool
@ -217,15 +228,7 @@ parse_opt (int key, char *arg, struct argp_state *state)
settings.keepLog = false;
break;
case GUIX_OPT_LISTEN:
try
{
settings.nixDaemonSocketFile = canonPath (arg);
}
catch (std::exception &e)
{
fprintf (stderr, _("error: %s\n"), e.what ());
exit (EXIT_FAILURE);
}
listen_options.push_back (arg);
break;
case GUIX_OPT_SUBSTITUTE_URLS:
settings.set ("substitute-urls", arg);
@ -276,13 +279,134 @@ static const struct argp argp =
guix_textdomain
};
static int
open_unix_domain_socket (const char *file)
{
/* Create and bind to a Unix domain socket. */
AutoCloseFD fdSocket = socket (PF_UNIX, SOCK_STREAM, 0);
if (fdSocket == -1)
throw SysError (_("cannot create Unix domain socket"));
createDirs (dirOf (file));
/* Urgh, sockaddr_un allows path names of only 108 characters.
So chdir to the socket directory so that we can pass a
relative path name. */
if (chdir (dirOf (file).c_str ()) == -1)
throw SysError (_("cannot change current directory"));
Path fileRel = "./" + baseNameOf (file);
struct sockaddr_un addr;
addr.sun_family = AF_UNIX;
if (fileRel.size () >= sizeof (addr.sun_path))
throw Error (format (_("socket file name '%1%' is too long")) % fileRel);
strcpy (addr.sun_path, fileRel.c_str ());
unlink (file);
/* Make sure that the socket is created with 0666 permission
(everybody can connect --- provided they have access to the
directory containing the socket). */
mode_t oldMode = umask (0111);
int res = bind (fdSocket, (struct sockaddr *) &addr, sizeof addr);
umask (oldMode);
if (res == -1)
throw SysError (format (_("cannot bind to socket '%1%'")) % file);
if (chdir ("/") == -1) /* back to the root */
throw SysError (_("cannot change current directory"));
if (listen (fdSocket, 5) == -1)
throw SysError (format (_("cannot listen on socket '%1%'")) % file);
return fdSocket.borrow ();
}
/* Return a listening socket for ADDRESS, which has the given LENGTH. */
static int
open_inet_socket (const struct sockaddr *address, socklen_t length)
{
AutoCloseFD fd = socket (address->sa_family, SOCK_STREAM, 0);
if (fd == -1)
throw SysError (_("cannot create TCP socket"));
int res = bind (fd, address, length);
if (res == -1)
throw SysError (_("cannot bind TCP socket"));
if (listen (fd, 5) == -1)
throw SysError (format (_("cannot listen on TCP socket")));
return fd.borrow ();
}
/* Return a list of file descriptors of listening sockets. */
static std::vector<int>
listening_sockets (const std::list<std::string> &options)
{
std::vector<int> result;
if (options.empty ())
{
/* Open the default Unix-domain socket. */
auto fd = open_unix_domain_socket (settings.nixDaemonSocketFile.c_str ());
result.push_back (fd);
return result;
}
/* Open the user-specified sockets. */
for (const std::string& option: options)
{
if (option[0] == '/')
{
/* Assume OPTION is the file name of a Unix-domain socket. */
settings.nixDaemonSocketFile = canonPath (option);
int fd =
open_unix_domain_socket (settings.nixDaemonSocketFile.c_str ());
result.push_back (fd);
}
else
{
/* Assume OPTIONS has the form "HOST" or "HOST:PORT". */
auto colon = option.find_last_of (":");
auto host = colon == std::string::npos
? option : option.substr (0, colon);
auto port = colon == std::string::npos
? DEFAULT_GUIX_PORT
: option.substr (colon + 1, option.size () - colon - 1);
struct addrinfo *res, hints;
memset (&hints, '\0', sizeof hints);
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_NUMERICSERV | AI_ADDRCONFIG;
int err = getaddrinfo (host.c_str(), port.c_str (),
&hints, &res);
if (err != 0)
throw Error(format ("failed to look up '%1%': %2%")
% option % gai_strerror (err));
printMsg (lvlDebug, format ("listening on '%1%', port '%2%'")
% host % port);
/* XXX: Pick the first result, RES. */
result.push_back (open_inet_socket (res->ai_addr,
res->ai_addrlen));
freeaddrinfo (res);
}
}
return result;
}
int
main (int argc, char *argv[])
{
static const Strings nothing;
setlocale (LC_ALL, "");
bindtextdomain (guix_textdomain, LOCALEDIR);
textdomain (guix_textdomain);
@ -359,6 +483,8 @@ main (int argc, char *argv[])
argp_parse (&argp, argc, argv, 0, 0, 0);
auto sockets = listening_sockets (listen_options);
/* Effect all the changes made via 'settings.set'. */
settings.update ();
@ -402,7 +528,7 @@ using `--build-users-group' is highly recommended\n"));
printMsg (lvlDebug,
format ("listening on `%1%'") % settings.nixDaemonSocketFile);
run (nothing);
run (sockets);
}
catch (std::exception &e)
{

273
nix/nix-daemon/nix-daemon.cc
View file

@ -18,6 +18,7 @@
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <errno.h>
#include <pwd.h>
@ -809,151 +810,87 @@ static void setSigChldAction(bool autoReap)
}
bool matchUser(const string & user, const string & group, const Strings & users)
/* Accept a connection on FDSOCKET and fork a server process to process the
new connection. */
static void acceptConnection(int fdSocket)
{
if (find(users.begin(), users.end(), "*") != users.end())
return true;
uid_t clientUid = (uid_t) -1;
gid_t clientGid = (gid_t) -1;
if (find(users.begin(), users.end(), user) != users.end())
return true;
try {
/* Important: the server process *cannot* open the SQLite
database, because it doesn't like forks very much. */
assert(!store);
for (auto & i : users)
if (string(i, 0, 1) == "@") {
if (group == string(i, 1)) return true;
struct group * gr = getgrnam(i.c_str() + 1);
if (!gr) continue;
for (char * * mem = gr->gr_mem; *mem; mem++)
if (user == string(*mem)) return true;
}
/* Accept a connection. */
struct sockaddr_storage remoteAddr;
socklen_t remoteAddrLen = sizeof(remoteAddr);
return false;
}
try_again:
AutoCloseFD remote = accept(fdSocket,
(struct sockaddr *) &remoteAddr, &remoteAddrLen);
checkInterrupt();
if (remote == -1) {
if (errno == EINTR)
goto try_again;
else
throw SysError("accepting connection");
}
closeOnExec(remote);
#define SD_LISTEN_FDS_START 3
static void daemonLoop()
{
if (chdir("/") == -1)
throw SysError("cannot change current directory");
/* Get rid of children automatically; don't let them become
zombies. */
setSigChldAction(true);
AutoCloseFD fdSocket;
/* Handle socket-based activation by systemd. */
if (getEnv("LISTEN_FDS") != "") {
if (getEnv("LISTEN_PID") != std::to_string(getpid()) || getEnv("LISTEN_FDS") != "1")
throw Error("unexpected systemd environment variables");
fdSocket = SD_LISTEN_FDS_START;
}
/* Otherwise, create and bind to a Unix domain socket. */
else {
/* Create and bind to a Unix domain socket. */
fdSocket = socket(PF_UNIX, SOCK_STREAM, 0);
if (fdSocket == -1)
throw SysError("cannot create Unix domain socket");
string socketPath = settings.nixDaemonSocketFile;
createDirs(dirOf(socketPath));
/* Urgh, sockaddr_un allows path names of only 108 characters.
So chdir to the socket directory so that we can pass a
relative path name. */
if (chdir(dirOf(socketPath).c_str()) == -1)
throw SysError("cannot change current directory");
Path socketPathRel = "./" + baseNameOf(socketPath);
struct sockaddr_un addr;
addr.sun_family = AF_UNIX;
if (socketPathRel.size() >= sizeof(addr.sun_path))
throw Error(format("socket path `%1%' is too long") % socketPathRel);
strcpy(addr.sun_path, socketPathRel.c_str());
unlink(socketPath.c_str());
/* Make sure that the socket is created with 0666 permission
(everybody can connect --- provided they have access to the
directory containing the socket). */
mode_t oldMode = umask(0111);
int res = bind(fdSocket, (struct sockaddr *) &addr, sizeof(addr));
umask(oldMode);
if (res == -1)
throw SysError(format("cannot bind to socket `%1%'") % socketPath);
if (chdir("/") == -1) /* back to the root */
throw SysError("cannot change current directory");
if (listen(fdSocket, 5) == -1)
throw SysError(format("cannot listen on socket `%1%'") % socketPath);
}
closeOnExec(fdSocket);
/* Loop accepting connections. */
while (1) {
try {
/* Important: the server process *cannot* open the SQLite
database, because it doesn't like forks very much. */
assert(!store);
/* Accept a connection. */
struct sockaddr_un remoteAddr;
socklen_t remoteAddrLen = sizeof(remoteAddr);
AutoCloseFD remote = accept(fdSocket,
(struct sockaddr *) &remoteAddr, &remoteAddrLen);
checkInterrupt();
if (remote == -1) {
if (errno == EINTR)
continue;
else
throw SysError("accepting connection");
}
closeOnExec(remote);
bool trusted = false;
pid_t clientPid = -1;
pid_t clientPid = -1;
bool trusted = false;
/* Get the identity of the caller, if possible. */
if (remoteAddr.ss_family == AF_UNIX) {
#if defined(SO_PEERCRED)
/* Get the identity of the caller, if possible. */
ucred cred;
socklen_t credLen = sizeof(cred);
if (getsockopt(remote, SOL_SOCKET, SO_PEERCRED, &cred, &credLen) == -1)
throw SysError("getting peer credentials");
ucred cred;
socklen_t credLen = sizeof(cred);
if (getsockopt(remote, SOL_SOCKET, SO_PEERCRED,
&cred, &credLen) == -1)
throw SysError("getting peer credentials");
clientPid = cred.pid;
clientPid = cred.pid;
clientUid = cred.uid;
clientGid = cred.gid;
trusted = clientUid == 0;
struct passwd * pw = getpwuid(cred.uid);
string user = pw ? pw->pw_name : std::to_string(cred.uid);
struct group * gr = getgrgid(cred.gid);
string group = gr ? gr->gr_name : std::to_string(cred.gid);
Strings trustedUsers = settings.get("trusted-users", Strings({"root"}));
Strings allowedUsers = settings.get("allowed-users", Strings({"*"}));
if (matchUser(user, group, trustedUsers))
trusted = true;
if (!trusted && !matchUser(user, group, allowedUsers))
throw Error(format("user `%1%' is not allowed to connect to the Nix daemon") % user);
printMsg(lvlInfo, format((string) "accepted connection from pid %1%, user %2%"
+ (trusted ? " (trusted)" : "")) % clientPid % user);
printMsg(lvlInfo,
format((string) "accepted connection from pid %1%, user %2%")
% clientPid % user);
#endif
} else {
char address_str[128];
const char *result;
/* Fork a child to handle the connection. */
startProcess([&]() {
fdSocket.close();
if (remoteAddr.ss_family == AF_INET) {
struct sockaddr_in *addr = (struct sockaddr_in *) &remoteAddr;
struct in_addr inaddr = { addr->sin_addr };
result = inet_ntop(AF_INET, &inaddr,
address_str, sizeof address_str);
} else if (remoteAddr.ss_family == AF_INET6) {
struct sockaddr_in6 *addr = (struct sockaddr_in6 *) &remoteAddr;
struct in6_addr inaddr = { addr->sin6_addr };
result = inet_ntop(AF_INET6, &inaddr,
address_str, sizeof address_str);
} else {
result = NULL;
}
if (result != NULL) {
printMsg(lvlInfo,
format("accepted connection from %1%")
% address_str);
}
}
/* Fork a child to handle the connection. */
startProcess([&]() {
close(fdSocket);
/* Background the daemon. */
if (setsid() == -1)
@ -968,17 +905,11 @@ static void daemonLoop()
strncpy(argvSaved[1], processName.c_str(), strlen(argvSaved[1]));
}
#if defined(SO_PEERCRED)
/* Store the client's user and group for this connection. This
has to be done in the forked process since it is per
connection. */
settings.clientUid = cred.uid;
settings.clientGid = cred.gid;
#else
/* Setting these to -1 means: do not change */
settings.clientUid = (uid_t) -1;
settings.clientGid = (gid_t) -1;
#endif
connection. Setting these to -1 means: do not change. */
settings.clientUid = clientUid;
settings.clientGid = clientGid;
/* Handle the connection. */
from.fd = remote;
@ -988,23 +919,63 @@ static void daemonLoop()
exit(0);
}, false, "unexpected Nix daemon error: ", true);
} catch (Interrupted & e) {
throw;
} catch (Error & e) {
printMsg(lvlError, format("error processing connection: %1%") % e.msg());
}
} catch (Interrupted & e) {
throw;
} catch (Error & e) {
printMsg(lvlError, format("error processing connection: %1%") % e.msg());
}
}
static void daemonLoop(const std::vector<int>& sockets)
{
if (chdir("/") == -1)
throw SysError("cannot change current directory");
/* Get rid of children automatically; don't let them become
zombies. */
setSigChldAction(true);
/* Mark sockets as close-on-exec. */
for(int fd: sockets) {
closeOnExec(fd);
}
/* Prepare the FD set corresponding to SOCKETS. */
auto initializeFDSet = [&](fd_set *set) {
FD_ZERO(set);
for (int fd: sockets) {
FD_SET(fd, set);
}
};
/* Loop accepting connections. */
while (1) {
fd_set readfds;
initializeFDSet(&readfds);
int count =
select(*std::max_element(sockets.begin(), sockets.end()) + 1,
&readfds, NULL, NULL,
NULL);
if (count < 0) {
int err = errno;
if (err == EINTR)
continue;
throw SysError(format("select error: %1%") % strerror(err));
}
for (unsigned int i = 0; i < sockets.size(); i++) {
if (FD_ISSET(sockets[i], &readfds)) {
acceptConnection(sockets[i]);
}
}
}
}
void run(Strings args)
void run(const std::vector<int>& sockets)
{
for (Strings::iterator i = args.begin(); i != args.end(); ) {
string arg = *i++;
if (arg == "--daemon") /* ignored for backwards compatibility */;
}
daemonLoop();
daemonLoop(sockets);
}

12
tests/guix-daemon.sh
View file

@ -81,6 +81,18 @@ guile -c "
kill "$daemon_pid"
# Pass several '--listen' options, and make sure they are all honored.
guix-daemon --disable-chroot --listen="$socket" --listen="$socket-second" \
--listen="localhost" --listen="localhost:9876" &
daemon_pid=$!
for uri in "$socket" "$socket-second" \
"guix://localhost" "guix://localhost:9876"
do
GUIX_DAEMON_SOCKET="$uri" guix build guile-bootstrap
done
kill "$daemon_pid"
# Check the failed build cache.