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logind: fail on CreateSession if already in session

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Right now, if you're already in a session and call CreateSession, we
return information about the current session of yours. This is highy
confusing and a nasty hack. Avoid that, and instead return a commonly
known error, so the caller can detect that.

This has the side-effect, that we no longer override XDG_VTNR and XDG_SEAT
in pam_systemd, if you're already in a session. But this sounds like the
right thing to do, anyway.
This commit is contained in:
David Herrmann 2015-07-07 19:38:41 +02:00
parent 586cd08e1b
commit b80120c4cb
4 changed files with 27 additions and 55 deletions
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1
src/libsystemd/sd-bus/bus-common-errors.h
View File

@ -58,6 +58,7 @@
#define BUS_ERROR_DEVICE_NOT_TAKEN "org.freedesktop.login1.DeviceNotTaken"
#define BUS_ERROR_OPERATION_IN_PROGRESS "org.freedesktop.login1.OperationInProgress"
#define BUS_ERROR_SLEEP_VERB_NOT_SUPPORTED "org.freedesktop.login1.SleepVerbNotSupported"
#define BUS_ERROR_SESSION_BUSY "org.freedesktop.login1.SessionBusy"
#define BUS_ERROR_AUTOMATIC_TIME_SYNC_ENABLED "org.freedesktop.timedate1.AutomaticTimeSyncEnabled"

4
src/login/logind-core.c
View File

@ -317,7 +317,6 @@ int manager_get_session_by_pid(Manager *m, pid_t pid, Session **session) {
int r;
assert(m);
assert(session);
if (pid < 1)
return -EINVAL;
@ -330,7 +329,8 @@ int manager_get_session_by_pid(Manager *m, pid_t pid, Session **session) {
if (!s)
return 0;
*session = s;
if (session)
*session = s;
return 1;
}

67
src/login/logind-dbus.c
View File

@ -689,58 +689,23 @@ static int method_create_session(sd_bus_message *message, void *userdata, sd_bus
return r;
}
manager_get_session_by_pid(m, leader, &session);
if (!session && vtnr > 0 && vtnr < m->seat0->position_count) {
session = m->seat0->positions[vtnr];
/*
* Old gdm and lightdm start the user-session on the same VT as
* the greeter session. But they destroy the greeter session
* after the user-session and want the user-session to take
* over the VT. We need to support this for
* backwards-compatibility, so make sure we allow new sessions
* on a VT that a greeter is running on.
*/
if (session && session->class == SESSION_GREETER)
session = NULL;
}
if (session) {
_cleanup_free_ char *path = NULL;
_cleanup_close_ int fifo_fd = -1;
r = manager_get_session_by_pid(m, leader, NULL);
if (r > 0)
return sd_bus_error_setf(error, BUS_ERROR_SESSION_BUSY, "Already running in a session");
/* Session already exists, client is probably
* something like "su" which changes uid but is still
* the same session */
fifo_fd = session_create_fifo(session);
if (fifo_fd < 0)
return fifo_fd;
path = session_bus_path(session);
if (!path)
return -ENOMEM;
log_debug("Sending reply about an existing session: "
"id=%s object_path=%s uid=%u runtime_path=%s "
"session_fd=%d seat=%s vtnr=%u",
session->id,
path,
(uint32_t) session->user->uid,
session->user->runtime_path,
fifo_fd,
session->seat ? session->seat->id : "",
(uint32_t) session->vtnr);
return sd_bus_reply_method_return(
message, "soshusub",
session->id,
path,
session->user->runtime_path,
fifo_fd,
(uint32_t) session->user->uid,
session->seat ? session->seat->id : "",
(uint32_t) session->vtnr,
true);
}
/*
* Old gdm and lightdm start the user-session on the same VT as
* the greeter session. But they destroy the greeter session
* after the user-session and want the user-session to take
* over the VT. We need to support this for
* backwards-compatibility, so make sure we allow new sessions
* on a VT that a greeter is running on.
*/
if (vtnr > 0 &&
vtnr < m->seat0->position_count &&
m->seat0->positions[vtnr] &&
m->seat0->positions[vtnr]->class != SESSION_GREETER)
return sd_bus_error_setf(error, BUS_ERROR_SESSION_BUSY, "Already occupied by a session");
audit_session_from_pid(leader, &audit_id);
if (audit_id > 0) {

10
src/login/pam_systemd.c
View File

@ -31,6 +31,7 @@
#include <security/pam_ext.h>
#include <security/pam_misc.h>
#include "bus-common-errors.h"
#include "util.h"
#include "audit.h"
#include "macro.h"
@ -399,8 +400,13 @@ _public_ PAM_EXTERN int pam_sm_open_session(
remote_host,
0);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
return PAM_SYSTEM_ERR;
if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
pam_syslog(handle, LOG_DEBUG, "Cannot create session: %s", bus_error_message(&error, r));
return PAM_SUCCESS;
} else {
pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
return PAM_SYSTEM_ERR;
}
}
r = sd_bus_message_read(reply,