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pam: do not attempt to close sd-bus after fork in pam_end()

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When pam_end() is called after a fork, and it cleans up caches, it sets
PAM_DATA_SILENT in error_status. FDs will be shared with the parent, so
we do not want to attempt to close them from a child process, or we'll
hit assertions. Complain loudly and skip.
This commit is contained in:
Luca Boccassi 2023-04-20 12:55:06 +01:00 committed by Zbigniew Jędrzejewski-Szmek
parent b4e5c103be
commit 4a75704b16
1 changed files with 11 additions and 0 deletions
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11
src/shared/pam-util.c
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@ -50,6 +50,17 @@ int pam_syslog_pam_error(pam_handle_t *handle, int level, int error, const char
}
static void cleanup_system_bus(pam_handle_t *handle, void *data, int error_status) {
/* The PAM_DATA_SILENT flag is the way that pam_end() communicates to the module stack that this
* invocation of pam_end() is not the final one, but in the process that is going to directly exec
* the child. This means we are being called after a fork(), and we do not want to try and clean
* up the sd-bus object, as it would affect the parent too and we'll hit an assertion. */
if (error_status & PAM_DATA_SILENT)
return (void) pam_syslog_pam_error(
handle,
LOG_ERR,
SYNTHETIC_ERRNO(EUCLEAN),
"Attempted to close sd-bus after fork, this should not happen.");
sd_bus_flush_close_unref(data);
}