SymbX/systemd
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

pam: cache sd-bus separately per module

Browse Source 
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
This commit is contained in:
Luca Boccassi
2023-04-24 14:18:50 +02:00
committed by Lennart Poettering
parent db0c0f5e00
commit a2dd39b4cb
4 changed files with 30 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/shared/pam-util.c
+18 -5
View File
@@ -53,15 +53,21 @@ static void cleanup_system_bus(pam_handle_t *handle, void *data, int error_statu
sd_bus_flush_close_unref(data);
}
int pam_acquire_bus_connection(pam_handle_t *handle, sd_bus **ret) {
int pam_acquire_bus_connection(pam_handle_t *handle, const char *module_name, sd_bus **ret) {
_cleanup_(sd_bus_unrefp) sd_bus *bus = NULL;
_cleanup_free_ char *cache_id = NULL;
int r;
assert(handle);
assert(module_name);
assert(ret);
cache_id = strjoin("system-bus-", module_name);
if (!cache_id)
return pam_log_oom(handle);
/* We cache the bus connection so that we can share it between the session and the authentication hooks */
r = pam_get_data(handle, "systemd-system-bus", (const void**) &bus);
r = pam_get_data(handle, cache_id, (const void**) &bus);
if (r == PAM_SUCCESS && bus) {
*ret = sd_bus_ref(TAKE_PTR(bus)); /* Increase the reference counter, so that the PAM data stays valid */
return PAM_SUCCESS;
@@ -73,7 +79,7 @@ int pam_acquire_bus_connection(pam_handle_t *handle, sd_bus **ret) {
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to connect to system bus: %m");
r = pam_set_data(handle, "systemd-system-bus", bus, cleanup_system_bus);
r = pam_set_data(handle, cache_id, bus, cleanup_system_bus);
if (r != PAM_SUCCESS)
return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to set PAM bus data: @PAMERR@");
@@ -83,10 +89,17 @@ int pam_acquire_bus_connection(pam_handle_t *handle, sd_bus **ret) {
return PAM_SUCCESS;
}
int pam_release_bus_connection(pam_handle_t *handle) {
int pam_release_bus_connection(pam_handle_t *handle, const char *module_name) {
_cleanup_free_ char *cache_id = NULL;
int r;
r = pam_set_data(handle, "systemd-system-bus", NULL, NULL);
assert(module_name);
cache_id = strjoin("system-bus-", module_name);
if (!cache_id)
return pam_log_oom(handle);
r = pam_set_data(handle, cache_id, NULL, NULL);
if (r != PAM_SUCCESS)
return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to release PAM user record data: @PAMERR@");
src/shared/pam-util.h
+4 -2
View File
@@ -24,7 +24,9 @@ static inline int pam_bus_log_parse_error(pam_handle_t *handle, int r) {
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to parse bus message: %m");
}
int pam_acquire_bus_connection(pam_handle_t *handle, sd_bus **ret);
int pam_release_bus_connection(pam_handle_t *handle);
/* Use a different module name per different PAM module. They are all loaded in the same namespace, and this
* helps avoid a clash in the internal data structures of sd-bus. It will be used as key for cache items. */
int pam_acquire_bus_connection(pam_handle_t *handle, const char *module_name, sd_bus **ret);
int pam_release_bus_connection(pam_handle_t *handle, const char *module_name);
void pam_cleanup_free(pam_handle_t *handle, void *data, int error_status);