A few weeks back I posted some prototype patches for PolicyKit support to allow the main libvirt daemon socket to be made world-accessible. PolicyKit then can do ACLs on incoming connections, allowing definition of rules which could for example, allow only the user who owns the active X login sesion
http://www.redhat.com/archives/libvir-list/2007-August/msg00027.html This is an updated patch which takes account of a change in the PolicyKit XML file syntax between 0.4 and 0.5 releases. The configure.in scripts has been tweaked to automatically disable PolicyKit if pkg-config is not available instead of aborting. The code for getting UNIX socket credentials has been factored out into its own method. There is still only a Linux implementation. I was going to take the code for other OS from DBus, but DBus is currently under a GPL/Academic license options, which is not compatible with LGPL. Fortunately DBus is in middle of re-licensing to X11 style which is LGPL compatible, so in a week or so's time we'll be able to safely take their OS portability code for socket credentials. I short-circuit the logic to always allow root. This allows existing people running libvirt tools as root to continue use without any regressions. There is one small issue still that the default policy I provide only allows the use of read-only connections if the user is logged into to the desktop. This is a partial regression - the admin can edit /etc/PolicyKit/PolicyKit.conf and add a site-local rule allowing all users access, regardless of whether they're in a session. I've spoken with David Zeuthan and he's going to add ability to specify rules for non-session clients in the default policy config files, which will fix this minor regression. Once this is done the libvirt default policy will be identical to current file permission based policy (root == full access, non-root == read only). As I mentioned previously, with this change it is now possible to open a full read-write connection from virt-manager running as non-root. Depending on site policy it will optionally prompt for root password (su style equiv) or the user's password (sudo style equiv) without needing virt-manager itself to gain any elevated privileges. When compiling with PolicyKit support, the default file permissions for both the main & readonly UNIX sockets in the daemon switch to 0777, instead of the previous 0700 & 0777. It is possible to turn off PolicyKit auth in the daemon config file, even if it is compiled in - in which case the default permissions get set back to 0700 & 0777. Although in previous feedback Daniel suggested I leave the LIBVIRTD_AUTH_POLKIT constant compiled in all the time, I feel it is better to remove it when the policykit support is disabled in configure. This removes the need to have extra switch/case statements to explicitly reject LIBVIRTD_AUTH_POLKIT auth, since it will be handle by the 'default:' statement which already has code to reject connections. I've done more extensive testing with virt-manager since my previous patch, and its working very nicely with the new UI which allows multiple hypervisor connections. Instead of asking for the root password up-front at app start time, we now only need ask for it if the user connects to a local HV. If they only ever manage remote connections we don't need to do anything with the local root password. Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|
diff -r a41065295371 configure.in --- a/configure.in Tue Sep 18 22:28:57 2007 -0400 +++ b/configure.in Tue Sep 18 22:30:19 2007 -0400 @@ -25,6 +25,7 @@ LIBXML_REQUIRED="2.5.0" LIBXML_REQUIRED="2.5.0" GNUTLS_REQUIRED="1.2.0" AVAHI_REQUIRED="0.6.0" +POLKIT_REQUIRED="0.5" dnl Checks for programs. AC_PROG_CC @@ -336,6 +337,32 @@ AM_CONDITIONAL(HAVE_AVAHI, [test "$with_ AM_CONDITIONAL(HAVE_AVAHI, [test "$with_avahi" = "yes"]) AC_SUBST(AVAHI_CFLAGS) AC_SUBST(AVAHI_LIBS) + +dnl PolicyKit library +AC_ARG_WITH(polkit, + [ --with-polkit use PolicyKit for UNIX socket access checks], + [], + [with_polkit=check]) + +if test "$with_polkit" = "check"; then + PKG_CHECK_EXISTS(polkit >= $POLKIT_REQUIRED, [with_polkit=yes], [with_polkit=no]) +fi + +if test "$with_polkit" = "yes"; then + PKG_CHECK_MODULES(POLKIT, polkit >= $POLKIT_REQUIRED) + PKG_CHECK_MODULES(POLKIT_DBUS, polkit-dbus >= $POLKIT_REQUIRED) + AC_DEFINE_UNQUOTED(HAVE_POLKIT, 1, [use PolicyKit for UNIX socket access checks]) +else + POLKIT_CFLAGS= + POLKIT_LIBS= + POLKIT_DBUS_CFLAGS= + POLKIT_DBUS_LIBS= +fi +AM_CONDITIONAL(HAVE_POLKIT, [test "$with_polkit" = "yes"]) +AC_SUBST(POLKIT_CFLAGS) +AC_SUBST(POLKIT_LIBS) +AC_SUBST(POLKIT_DBUS_CFLAGS) +AC_SUBST(POLKIT_DBUS_LIBS) dnl virsh libraries AC_CHECK_LIB(curses, initscr, @@ -528,6 +555,11 @@ else else AC_MSG_NOTICE([ avahi: no]) fi +if test "$with_polkit" = "yes" ; then +AC_MSG_NOTICE([ polkit: $POLKIT_CFLAGS $POLKIT_LIBS $POLKIT_DBUS_CFLAGS $POLKIT_DBUS_LIBS]) +else +AC_MSG_NOTICE([ polkit: no]) +fi AC_MSG_NOTICE([]) AC_MSG_NOTICE([Miscellaneous]) AC_MSG_NOTICE([]) diff -r a41065295371 qemud/Makefile.am --- a/qemud/Makefile.am Tue Sep 18 22:28:57 2007 -0400 +++ b/qemud/Makefile.am Tue Sep 18 22:30:19 2007 -0400 @@ -42,6 +42,16 @@ libvirtd_CFLAGS += $(AVAHI_CFLAGS) libvirtd_CFLAGS += $(AVAHI_CFLAGS) libvirtd_LDADD += $(AVAHI_LIBS) endif + +if HAVE_POLKIT +libvirtd_CFLAGS += $(POLKIT_CFLAGS) $(POLKIT_DBUS_CFLAGS) +libvirtd_LDADD += $(POLKIT_LIBS) $(POLKIT_DBUS_LIBS) + +policydir = $(datadir)/PolicyKit/policy +policy_DATA = libvirtd.policy +endif +EXTRA_DIST += libvirtd.policy + install-data-local: install-init mkdir -p $(DESTDIR)$(sysconfdir)/libvirt/qemu/networks/autostart diff -r a41065295371 qemud/internal.h --- a/qemud/internal.h Tue Sep 18 22:28:57 2007 -0400 +++ b/qemud/internal.h Tue Sep 18 22:30:19 2007 -0400 @@ -28,6 +28,9 @@ #include <gnutls/gnutls.h> #include <gnutls/x509.h> #include "../src/gnutls_1_0_compat.h" +#ifdef HAVE_POLKIT +#include "dbus/dbus.h" +#endif #include "protocol.h" #include "remote_protocol.h" @@ -57,6 +60,13 @@ typedef enum { #endif } qemudLogPriority; +enum libvirtd_auth { + LIBVIRTD_AUTH_NONE, + LIBVIRTD_AUTH_TLS, +#ifdef HAVE_POLKIT + LIBVIRTD_AUTH_POLKIT, +#endif +}; enum qemud_mode { QEMUD_MODE_RX_HEADER, @@ -82,8 +92,8 @@ struct qemud_client { struct sockaddr_storage addr; socklen_t addrlen; - /* If set, TLS is required on this socket. */ - int tls; + /* Required auth mode for incoming connections */ + int auth; gnutls_session_t session; enum qemud_tls_direction direction; @@ -109,8 +119,8 @@ struct qemud_socket { struct qemud_socket { int fd; int readonly; - /* If set, TLS is required on this socket. */ - int tls; + /* Required auth mode for incoming connections */ + int auth; int port; struct qemud_socket *next; }; @@ -127,6 +137,9 @@ struct qemud_server { #ifdef HAVE_AVAHI struct libvirtd_mdns *mdns; #endif +#ifdef HAVE_POLKIT + DBusConnection *sysbus; +#endif }; void qemudLog(int priority, const char *fmt, ...) diff -r a41065295371 qemud/libvirtd.policy --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/qemud/libvirtd.policy Tue Sep 18 22:30:19 2007 -0400 @@ -0,0 +1,36 @@ +<!DOCTYPE policyconfig PUBLIC + "-//freedesktop//DTD PolicyKit Policy Configuration 1.0//EN" + "http://www.freedesktop.org/standards/PolicyKit/1.0/policyconfig.dtd"> + +<!-- +Policy definitions for libvirt daemon + +Copyright (c) 2007 Daniel P. Berrange <[EMAIL PROTECTED]> + +libvirt is licensed to you under the GNU Lesser General Public License +version 2. See COPYING for details. + +NOTE: If you make changes to this file, make sure to validate the file +using the polkit-policy-file-validate(1) tool. Changes made to this +file are instantly applied. +--> + +<policyconfig> + <action id="org.libvirt.local.monitor"> + <description>Monitor local virtualized systems</description> + <message>System policy prevents monitoring of local virtualized systems</message> + <defaults> + <allow_inactive>yes</allow_inactive> + <allow_active>yes</allow_active> + </defaults> + </action> + + <action id="org.libvirt.local.manage"> + <description>Manage local virtualized systems</description> + <message>System policy prevents management of local virtualized systems</message> + <defaults> + <allow_inactive>no</allow_inactive> + <allow_active>auth_self_keep_session</allow_active> + </defaults> + </action> +</policyconfig> diff -r a41065295371 qemud/qemud.c --- a/qemud/qemud.c Tue Sep 18 22:28:57 2007 -0400 +++ b/qemud/qemud.c Tue Sep 18 22:30:19 2007 -0400 @@ -61,6 +61,11 @@ #include "mdns.h" #endif +#ifdef HAVE_POLKIT +#include <polkit/polkit.h> +#include <polkit-dbus/polkit-dbus.h> +#endif + static int godaemon = 0; /* -d: Be a daemon */ static int verbose = 0; /* -v: Verbose mode */ static int timeout = -1; /* -t: Shutdown timeout */ @@ -73,8 +78,15 @@ static const char *tls_port = LIBVIRTD_T static const char *tls_port = LIBVIRTD_TLS_PORT; static const char *tcp_port = LIBVIRTD_TCP_PORT; +#ifdef HAVE_POLKIT +static int unix_sock_polkit = 1; /* Use PolicyKit for UNIX auth */ +#endif static gid_t unix_sock_gid = 0; /* Only root by default */ +#ifdef HAVE_POLKIT +static int unix_sock_rw_perms = 0777; /* Allow world (ACL with PolicyKit) */ +#else static int unix_sock_rw_perms = 0700; /* Allow user only */ +#endif static int unix_sock_ro_perms = 0777; /* Allow world */ #ifdef HAVE_AVAHI @@ -463,6 +475,11 @@ static int qemudListenUnix(struct qemud_ sock->readonly = readonly; sock->port = -1; +#ifdef HAVE_POLKIT + sock->auth = unix_sock_polkit ? LIBVIRTD_AUTH_POLKIT : LIBVIRTD_AUTH_NONE; +#else + sock->auth = LIBVIRTD_AUTH_NONE; +#endif if ((sock->fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) { qemudLog(QEMUD_ERR, "Failed to create socket: %s", @@ -577,7 +594,7 @@ static int static int remoteListenTCP (struct qemud_server *server, const char *port, - int tls) + int auth) { int fds[2]; int nfds = 0; @@ -605,7 +622,7 @@ remoteListenTCP (struct qemud_server *se server->nsockets++; sock->fd = fds[i]; - sock->tls = tls; + sock->auth = auth; if (getsockname(sock->fd, (struct sockaddr *)(&sa), &salen) < 0) return -1; @@ -719,6 +736,20 @@ static struct qemud_server *qemudInitial if (roSockname[0] != '\0' && qemudListenUnix(server, roSockname, 1) < 0) goto cleanup; +#ifdef HAVE_POLKIT + if (unix_sock_polkit) { + DBusError err; + dbus_error_init(&err); + server->sysbus = dbus_bus_get(DBUS_BUS_SYSTEM, &err); + if (!(server->sysbus)) { + qemudLog(QEMUD_ERR, "Failed to connect to system bus for PolicyKit auth: %s", + err.message); + dbus_error_free(&err); + goto cleanup; + } + } +#endif + __virEventRegisterImpl(virEventAddHandleImpl, virEventUpdateHandleImpl, virEventRemoveHandleImpl, @@ -729,14 +760,14 @@ static struct qemud_server *qemudInitial virStateInitialize(); if (ipsock) { - if (listen_tcp && remoteListenTCP (server, tcp_port, 0) < 0) + if (listen_tcp && remoteListenTCP (server, tcp_port, LIBVIRTD_AUTH_NONE) < 0) goto cleanup; if (listen_tls) { if (remoteInitializeGnuTLS () < 0) goto cleanup; - if (remoteListenTCP (server, tls_port, 1) < 0) + if (remoteListenTCP (server, tls_port, LIBVIRTD_AUTH_TLS) < 0) goto cleanup; } } @@ -769,7 +800,7 @@ static struct qemud_server *qemudInitial */ sock = server->sockets; while (sock) { - if (sock->port != -1 && sock->tls) { + if (sock->port != -1 && sock->auth == LIBVIRTD_AUTH_TLS) { port = sock->port; break; } @@ -795,6 +826,10 @@ static struct qemud_server *qemudInitial sock = sock->next; } +#ifdef HAVE_POLKIT + if (server->sysbus) + dbus_connection_unref(server->sysbus); +#endif free(server); } return NULL; @@ -1017,12 +1052,32 @@ remoteCheckAccess (struct qemud_client * return 0; } +static int qemudGetSocketIdentity(int fd, uid_t *uid, pid_t *pid) { +#ifdef SO_PEERCRED + struct ucred cr; + unsigned int cr_len = sizeof (cr); + + if (getsockopt (fd, SOL_SOCKET, SO_PEERCRED, &cr, &cr_len) < 0) { + qemudLog(QEMUD_ERR, "Failed to verify client credentials: %s", strerror(errno)); + return -1; + } + + *pid = cr.pid; + *uid = cr.uid; +#else + /* XXX Many more OS support UNIX socket credentials we could port to. See dbus ....*/ +#error "UNIX socket credentials not supported/implemented on this platform yet..." +#endif + return 0; +} + static int qemudDispatchServer(struct qemud_server *server, struct qemud_socket *sock) { int fd; struct sockaddr_storage addr; socklen_t addrlen = (socklen_t) (sizeof addr); struct qemud_client *client; int no_slow_start = 1; + int ret; if ((fd = accept(sock->fd, (struct sockaddr *)&addr, &addrlen)) < 0) { if (errno == EAGAIN) @@ -1045,19 +1100,105 @@ static int qemudDispatchServer(struct qe client->magic = QEMUD_CLIENT_MAGIC; client->fd = fd; client->readonly = sock->readonly; - client->tls = sock->tls; + client->auth = sock->auth; memcpy (&client->addr, &addr, sizeof addr); client->addrlen = addrlen; - if (!client->tls) { + qemudDebug("Authenticating new client on fd %d with mode %d", client->fd, client->auth); + + switch (client->auth) { +#ifdef HAVE_POLKIT + case LIBVIRTD_AUTH_POLKIT: + { + PolKitCaller *pkcaller = NULL; + PolKitAction *pkaction = NULL; + PolKitContext *pkcontext = NULL; + PolKitError *pkerr; + PolKitResult pkresult; + const char *action = sock->readonly ? + "org.libvirt.local.monitor" : + "org.libvirt.local.manage"; + pid_t callerPid; + uid_t callerUid; + DBusError err; + + if (qemudGetSocketIdentity(fd, &callerUid, &callerPid) < 0) { + close(fd); + free(client); + return -1; + } + + /* Only do policy checks for non-root - allow root user + through with no checks, so ssh sessions running as root + succeed - PolicyKit only works within X sessions */ + if (callerUid == 0) { + qemudLog(QEMUD_INFO, "Allowing PID %d running as root", callerPid); + } else { + qemudLog(QEMUD_INFO, "Checking PID %d running as %d", callerPid, callerUid); + dbus_error_init(&err); + if (!(pkcaller = polkit_caller_new_from_pid(server->sysbus, callerPid, &err))) { + qemudLog(QEMUD_ERR, "Failed to lookup policy kit caller: %s", err.message); + dbus_error_free(&err); + close(fd); + free(client); + return -1; + } + + if (!(pkaction = polkit_action_new())) { + qemudLog(QEMUD_ERR, "Failed to create polkit action %s\n", strerror(errno)); + polkit_caller_unref(pkcaller); + close(fd); + free(client); + return -1; + } + polkit_action_set_action_id(pkaction, action); + + if (!(pkcontext = polkit_context_new()) || + !polkit_context_init(pkcontext, &pkerr)) { + qemudLog(QEMUD_ERR, "Failed to create polkit context %s\n", + pkerr ? polkit_error_get_error_message(pkerr) : strerror(errno)); + if (pkerr) + polkit_error_free(pkerr); + polkit_caller_unref(pkcaller); + polkit_action_unref(pkaction); + dbus_error_free(&err); + close(fd); + free(client); + return -1; + } + + pkresult = polkit_context_can_caller_do_action(pkcontext, pkaction, pkcaller); + polkit_context_unref(pkcontext); + polkit_caller_unref(pkcaller); + polkit_action_unref(pkaction); + if (pkresult != POLKIT_RESULT_YES) { + qemudLog(QEMUD_ERR, "Policy kit denied action %s from pid %d, uid %d, result: %s\n", + action, callerPid, callerUid, polkit_result_to_string_representation(pkresult)); + close(fd); + free(client); + return -1; + } + qemudLog(QEMUD_INFO, "Policy allowed action %s from pid %d, uid %d, result %s", + action, callerPid, callerUid, polkit_result_to_string_representation(pkresult)); + } + } client->mode = QEMUD_MODE_RX_HEADER; client->bufferLength = QEMUD_PKT_HEADER_XDR_LEN; if (qemudRegisterClientEvent (server, client, 0) < 0) goto cleanup; - } else { - int ret; - + break; +#endif + + case LIBVIRTD_AUTH_NONE: + client->mode = QEMUD_MODE_RX_HEADER; + client->bufferLength = QEMUD_PKT_HEADER_XDR_LEN; + + if (qemudRegisterClientEvent (server, client, 0) < 0) + goto cleanup; + break; + + case LIBVIRTD_AUTH_TLS: client->session = remoteInitializeTLSSession (); if (client->session == NULL) goto cleanup; @@ -1087,6 +1228,12 @@ static int qemudDispatchServer(struct qe gnutls_strerror (ret)); goto cleanup; } + + default: + qemudLog(QEMUD_ERR, "Unknown/illegal authentication scheme configured: %d\n", sock->auth); + close(fd); + free(client); + return -1; } client->next = server->clients; @@ -1126,7 +1273,8 @@ static void qemudDispatchClientFailure(s if (client->conn) virConnectClose(client->conn); - if (client->tls && client->session) gnutls_deinit (client->session); + if (client->auth == LIBVIRTD_AUTH_TLS && client->session) + gnutls_deinit (client->session); close(client->fd); free(client); } @@ -1143,7 +1291,7 @@ static int qemudClientRead(struct qemud_ /*qemudDebug ("qemudClientRead: len = %d", len);*/ - if (!client->tls) { + if (client->auth != LIBVIRTD_AUTH_TLS) { if ((ret = read (client->fd, data, len)) <= 0) { if (ret == 0 || errno != EAGAIN) { if (ret != 0) @@ -1211,7 +1359,8 @@ static void qemudDispatchClientRead(stru client->mode = QEMUD_MODE_RX_PAYLOAD; client->bufferLength = h.length; - if (client->tls) client->direction = QEMUD_TLS_DIRECTION_READ; + if (client->auth == LIBVIRTD_AUTH_TLS) + client->direction = QEMUD_TLS_DIRECTION_READ; /* Note that we don't reset bufferOffset here because we want * to retain the whole message, including header. */ @@ -1299,7 +1448,7 @@ static int qemudClientWrite(struct qemud data = client->buffer + client->bufferOffset; len = client->bufferLength - client->bufferOffset; - if (!client->tls) { + if (client->auth != LIBVIRTD_AUTH_TLS) { if ((ret = write(client->fd, data, len)) == -1) { if (errno != EAGAIN) { qemudLog (QEMUD_ERR, "write: %s", strerror (errno)); @@ -1338,7 +1487,8 @@ static void qemudDispatchClientWrite(str client->mode = QEMUD_MODE_RX_HEADER; client->bufferLength = QEMUD_PKT_HEADER_XDR_LEN; client->bufferOffset = 0; - if (client->tls) client->direction = QEMUD_TLS_DIRECTION_READ; + if (client->auth == LIBVIRTD_AUTH_TLS) + client->direction = QEMUD_TLS_DIRECTION_READ; if (qemudRegisterClientEvent (server, client, 1) < 0) qemudDispatchClientFailure (server, client); @@ -1407,7 +1557,7 @@ static int qemudRegisterClientEvent(stru if (virEventRemoveHandleImpl(client->fd) < 0) return -1; - if (client->tls) { + if (client->auth == LIBVIRTD_AUTH_TLS) { if (virEventAddHandleImpl(client->fd, (client->direction ? POLLOUT : POLLIN) | POLLERR | POLLHUP, @@ -1564,6 +1714,16 @@ remoteReadConfigFile (const char *filena p = virConfGetValue (conf, "tcp_port"); CHECK_TYPE ("tcp_port", VIR_CONF_STRING); tcp_port = p ? strdup (p->str) : tcp_port; + +#ifdef HAVE_POLKIT + p = virConfGetValue (conf, "unix_sock_polkit"); + CHECK_TYPE ("unix_auth_polkit", VIR_CONF_LONG); + unix_sock_polkit = p ? p->l : unix_sock_polkit; + if (unix_sock_polkit) + unix_sock_rw_perms = 0777; + else + unix_sock_rw_perms = 0700; +#endif p = virConfGetValue (conf, "unix_sock_group"); CHECK_TYPE ("unix_sock_group", VIR_CONF_STRING); diff -r a41065295371 qemud/remote.c --- a/qemud/remote.c Tue Sep 18 22:28:57 2007 -0400 +++ b/qemud/remote.c Tue Sep 18 22:30:19 2007 -0400 @@ -266,7 +266,8 @@ remoteDispatchClientRequest (struct qemu client->mode = QEMUD_MODE_TX_PACKET; client->bufferLength = len; client->bufferOffset = 0; - if (client->tls) client->direction = QEMUD_TLS_DIRECTION_WRITE; + if (client->auth == LIBVIRTD_AUTH_TLS) + client->direction = QEMUD_TLS_DIRECTION_WRITE; } /* An error occurred during the dispatching process itself (ie. not @@ -360,7 +361,8 @@ remoteDispatchError (struct qemud_client client->mode = QEMUD_MODE_TX_PACKET; client->bufferLength = len; client->bufferOffset = 0; - if (client->tls) client->direction = QEMUD_TLS_DIRECTION_WRITE; + if (client->auth == LIBVIRTD_AUTH_TLS) + client->direction = QEMUD_TLS_DIRECTION_WRITE; } /*----- Functions. -----*/
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