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/*++
/* NAME
/* maillog_client 3
/* SUMMARY
/* choose between syslog client and postlog client
/* SYNOPSIS
/* #include <maillog_client.h>
/*
/* int maillog_client_init(
/* const char *progname,
/* int flags)
/* DESCRIPTION
/* maillog_client_init() chooses between logging to the syslog
/* service or to the internal postlog service.
/*
/* maillog_client_init() may be called before configuration
/* parameters are initialized. During this time, logging is
/* controlled by the presence or absence of POSTLOG_SERVICE
/* in the process environment (this is ignored if a program
/* runs with set-uid or set-gid permissions).
/*
/* maillog_client_init() may also be called after configuration
/* parameters are initialized. During this time, logging is
/* controlled by the "maillog_file" parameter value.
/*
/* Arguments:
/* .IP progname
/* The program name that will be prepended to logfile records.
/* .IP flags
/* Specify one of the following:
/* .RS
/* .IP MAILLOG_CLIENT_FLAG_NONE
/* No special processing.
/* .IP MAILLOG_CLIENT_FLAG_LOGWRITER_FALLBACK
/* Try to fall back to writing the "maillog_file" directly,
/* if logging to the internal postlog service is enabled, but
/* the postlog service is unavailable. If the fallback fails,
/* die with a fatal error.
/* .RE
/* ENVIRONMENT
/* .ad
/* .fi
/* When logging to the internal postlog service is enabled,
/* each process exports the following information, to help
/* initialize the logging in a child process, before the child
/* has initialized its configuration parameters.
/* .IP POSTLOG_SERVICE
/* The pathname of the public postlog service endpoint, usually
/* "$queue_directory/public/$postlog_service_name".
/* .IP POSTLOG_HOSTNAME
/* The hostname to prepend to information that is sent to the
/* internal postlog logging service, usually "$myhostname".
/* CONFIGURATION PARAMETERS
/* .ad
/* .fi
/* .IP "maillog_file (empty)"
/* The name of an optional logfile. If the value is empty, or
/* unitialized and the process environment does not specify
/* POSTLOG_SERVICE, the program will log to the syslog service
/* instead.
/* .IP "myhostname (default: see postconf -d output)"
/* The internet hostname of this mail system.
/* .IP "postlog_service_name (postlog)"
/* The name of the internal postlog logging service.
/* SEE ALSO
/* msg_syslog(3) syslog client
/* msg_logger(3) internal logger
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this
/* software.
/* AUTHOR(S)
/* Wietse Venema
/* Google, Inc.
/* 111 8th Avenue
/* New York, NY 10011, USA
/*--*/
/*
* System library.
*/
#include <sys_defs.h>
#include <stdlib.h>
#include <string.h>
/*
* Utility library.
*/
#include <argv.h>
#include <logwriter.h>
#include <msg_logger.h>
#include <msg_syslog.h>
#include <safe.h>
#include <stringops.h>
/*
* Global library.
*/
#include <mail_params.h>
#include <mail_proto.h>
#include <maillog_client.h>
#include <msg.h>
/*
* Using logging to debug logging is painful.
*/
#define MAILLOG_CLIENT_DEBUG 0
/*
* Application-specific.
*/
static int maillog_client_flags;
#define POSTLOG_SERVICE_ENV "POSTLOG_SERVICE"
#define POSTLOG_HOSTNAME_ENV "POSTLOG_HOSTNAME"
/* maillog_client_logwriter_fallback - fall back to logfile writer or bust */
static void maillog_client_logwriter_fallback(const char *text)
{
static int fallback_guard = 0;
/*
* Guard against recursive calls.
*
* If an error happened before the maillog_file parameter was initialized,
* or if maillog_file logging is disabled, then we cannot fall back to a
* logfile. All we can do is to hope that stderr logging will bring out
* the bad news.
*/
if (fallback_guard == 0 && var_maillog_file && *var_maillog_file
&& logwriter_one_shot(var_maillog_file, text, strlen(text)) < 0) {
fallback_guard = 1;
msg_fatal("logfile '%s' write error: %m", var_maillog_file);
}
}
/* maillog_client_init - set up syslog or internal log client */
void maillog_client_init(const char *progname, int flags)
{
char *import_service_path;
char *import_hostname;
/*
* Crucially, only one logger mode can be in effect at any time,
* otherwise postlogd(8) may go into a loop.
*/
enum {
MAILLOG_CLIENT_MODE_SYSLOG, MAILLOG_CLIENT_MODE_POSTLOG,
} logger_mode;
/*
* Security: this code may run before the import_environment setting has
* taken effect. It has to guard against privilege escalation attacks on
* setgid programs, using malicious environment settings.
*
* Import the postlog service name and hostname from the environment.
*
* - These will be used and kept if the process has not yet initialized its
* configuration parameters.
*
* - These will be set or updated if the configuration enables postlog
* logging.
*
* - These will be removed if the configuration does not enable postlog
* logging.
*/
if ((import_service_path = safe_getenv(POSTLOG_SERVICE_ENV)) != 0
&& *import_service_path == 0)
import_service_path = 0;
if ((import_hostname = safe_getenv(POSTLOG_HOSTNAME_ENV)) != 0
&& *import_hostname == 0)
import_hostname = 0;
#if MAILLOG_CLIENT_DEBUG
#define STRING_OR_NULL(s) ((s) ? (s) : "(null)")
msg_syslog_init(progname, LOG_PID, LOG_FACILITY);
msg_info("import_service_path=%s", STRING_OR_NULL(import_service_path));
msg_info("import_hostname=%s", STRING_OR_NULL(import_hostname));
#endif
/*
* Before configuration parameters are initialized, the logging mode is
* controlled by the presence or absence of POSTLOG_SERVICE in the
* process environment. After configuration parameters are initialized,
* the logging mode is controlled by the "maillog_file" parameter value.
*
* The configured mode may change after a process is started. The
* postlogd(8) server will proxy logging to syslogd where needed.
*/
if (var_maillog_file ? *var_maillog_file == 0 : import_service_path == 0) {
logger_mode = MAILLOG_CLIENT_MODE_SYSLOG;
} else {
/* var_maillog_file ? *var_maillog_file : import_service_path != 0 */
logger_mode = MAILLOG_CLIENT_MODE_POSTLOG;
}
/*
* Postlog logging is enabled. Update the 'progname' as that may have
* changed since an earlier call, and update the environment settings if
* they differ from configuration settings. This blends two code paths,
* one code path where configuration parameters are initialized (the
* preferred path), and one code path that uses imports from environment.
*/
if (logger_mode == MAILLOG_CLIENT_MODE_POSTLOG) {
char *myhostname;
char *service_path;
if (var_maillog_file && *var_maillog_file) {
ARGV *good_prefixes = argv_split(var_maillog_file_pfxs,
CHARS_COMMA_SP);
char **cpp;
for (cpp = good_prefixes->argv; /* see below */ ; cpp++) {
if (*cpp == 0)
msg_fatal("%s value '%s' does not match any prefix in %s",
VAR_MAILLOG_FILE, var_maillog_file,
VAR_MAILLOG_FILE_PFXS);
if (strncmp(var_maillog_file, *cpp, strlen(*cpp)) == 0)
break;
}
argv_free(good_prefixes);
}
if (var_myhostname && *var_myhostname) {
myhostname = var_myhostname;
} else if ((myhostname = import_hostname) == 0) {
myhostname = "amnesiac";
}
#if MAILLOG_CLIENT_DEBUG
msg_info("myhostname=%s", STRING_OR_NULL(myhostname));
#endif
if (var_postlog_service) {
service_path = concatenate(var_queue_dir, "/", MAIL_CLASS_PUBLIC,
"/", var_postlog_service, (char *) 0);
} else {
/*
* var_postlog_service == 0, therefore var_maillog_file == 0.
* logger_mode == MAILLOG_CLIENT_MODE_POSTLOG && var_maillog_file ==
* 0, therefore import_service_path != 0.
*/
service_path = import_service_path;
}
maillog_client_flags = flags;
msg_logger_init(progname, myhostname, service_path,
(flags & MAILLOG_CLIENT_FLAG_LOGWRITER_FALLBACK) ?
maillog_client_logwriter_fallback :
(MSG_LOGGER_FALLBACK_FN) 0);
/*
* Export or update the exported postlog service pathname and the
* hostname, so that a child process can bootstrap postlog logging
* before it has processed main.cf and command-line options.
*/
if (import_service_path == 0
|| strcmp(service_path, import_service_path) != 0) {
#if MAILLOG_CLIENT_DEBUG
msg_info("export %s=%s", POSTLOG_SERVICE_ENV, service_path);
#endif
if (setenv(POSTLOG_SERVICE_ENV, service_path, 1) < 0)
msg_fatal("setenv: %m");
}
if (import_hostname == 0 || strcmp(myhostname, import_hostname) != 0) {
#if MAILLOG_CLIENT_DEBUG
msg_info("export %s=%s", POSTLOG_HOSTNAME_ENV, myhostname);
#endif
if (setenv(POSTLOG_HOSTNAME_ENV, myhostname, 1) < 0)
msg_fatal("setenv: %m");
}
if (service_path != import_service_path)
myfree(service_path);
msg_logger_control(CA_MSG_LOGGER_CTL_CONNECT_NOW,
CA_MSG_LOGGER_CTL_END);
}
/*
* Postlog logging is disabled. Silence the msg_logger client, and remove
* the environment settings that bootstrap postlog logging in a child
* process.
*/
else {
msg_logger_control(CA_MSG_LOGGER_CTL_DISABLE, CA_MSG_LOGGER_CTL_END);
if ((import_service_path && unsetenv(POSTLOG_SERVICE_ENV))
|| (import_hostname && unsetenv(POSTLOG_HOSTNAME_ENV)))
msg_fatal("unsetenv: %m");
}
/*
* Syslog logging is enabled. Update the 'progname' as that may have
* changed since an earlier call.
*/
if (logger_mode == MAILLOG_CLIENT_MODE_SYSLOG) {
msg_syslog_init(progname, LOG_PID, LOG_FACILITY);
}
/*
* Syslog logging is disabled, silence the syslog client.
*/
else {
msg_syslog_disable();
}
}
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