pam: cache sd-bus separately per module

sd-bus connection is cached by the two pam modules globally, but this
can lead to issues due to hashmaps (used by sd-bus) using a global
static variable for the shared hash key, which is different per module
as both modules are loaded in the same process.

This happens because the sd-bus object is create in one module, but
used in the other, so global state does not match.

Use a different pam cache identifier for the sd-bus pointer, so that
each module uses a different sd-bus connection as a workaround.

Fixes https://github.com/systemd/systemd/issues/27216
Fixes https://github.com/systemd/systemd/issues/17266

1 files changed, 5 insertions, 5 deletions

diff --git a/src/home/pam_systemd_home.c b/src/home/pam_systemd_home.c
index e28c95f787..6a3e656035 100644
--- a/src/home/pam_systemd_home.c
+++ b/src/home/pam_systemd_home.c
@@ -140,7 +140,7 @@ static int acquire_user_record(
                 _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
                 _cleanup_free_ char *generic_field = NULL, *json_copy = NULL;
 
-                r = pam_acquire_bus_connection(handle, &bus);
+                r = pam_acquire_bus_connection(handle, "pam-systemd-home", &bus);
                 if (r != PAM_SUCCESS)
                         return r;
 
@@ -513,7 +513,7 @@ static int acquire_home(
         if (r == PAM_SUCCESS && PTR_TO_FD(home_fd_ptr) >= 0)
                 return PAM_SUCCESS;
 
-        r = pam_acquire_bus_connection(handle, &bus);
+        r = pam_acquire_bus_connection(handle, "pam-systemd-home", &bus);
         if (r != PAM_SUCCESS)
                 return r;
 
@@ -745,7 +745,7 @@ success:
         /* Let's release the D-Bus connection, after all the session might live quite a long time, and we are
          * not going to process the bus connection in that time, so let's better close before the daemon
          * kicks us off because we are not processing anything. */
-        (void) pam_release_bus_connection(handle);
+        (void) pam_release_bus_connection(handle, "pam-systemd-home");
         return PAM_SUCCESS;
 }
 
@@ -785,7 +785,7 @@ _public_ PAM_EXTERN int pam_sm_close_session(
         if (r != PAM_SUCCESS)
                 return r;
 
-        r = pam_acquire_bus_connection(handle, &bus);
+        r = pam_acquire_bus_connection(handle, "pam-systemd-home", &bus);
         if (r != PAM_SUCCESS)
                 return r;
 
@@ -944,7 +944,7 @@ _public_ PAM_EXTERN int pam_sm_chauthtok(
         if (debug)
                 pam_syslog(handle, LOG_DEBUG, "pam-systemd-homed account management");
 
-        r = pam_acquire_bus_connection(handle, &bus);
+        r = pam_acquire_bus_connection(handle, "pam-systemd-home", &bus);
         if (r != PAM_SUCCESS)
                 return r;