audit-bsm.c

OpenSSH 是 SSH （Secure SHell） 协议的免费开源实现。它用安全、加密的网络连接工具代替了 telnet、ftp、 rlogin、rsh 和 rcp 工具。OpenSSH 支持

/* $Id: audit-bsm.c,v 1.1 2005/02/20 10:08:00 dtucker Exp $ */

/*
 * TODO
 *
 * - deal with overlap between this and sys_auth_allowed_user
 *   sys_auth_record_login and record_failed_login.
 */

/*
 * Copyright 1988-2002 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
/* #pragma ident	"@(#)bsmaudit.c	1.1	01/09/17 SMI" */

#include "includes.h"
#if defined(USE_BSM_AUDIT)

#include "ssh.h"
#include "log.h"
#include "auth.h"
#include "xmalloc.h"

#ifndef AUE_openssh
# define AUE_openssh     32800
#endif
#include <bsm/audit.h>
#include <bsm/libbsm.h>
#include <bsm/audit_uevents.h>
#include <bsm/audit_record.h>
#include <locale.h>

#if defined(HAVE_GETAUDIT_ADDR)
#define	AuditInfoStruct		auditinfo_addr
#define AuditInfoTermID		au_tid_addr_t
#define GetAuditFunc(a,b)	getaudit_addr((a),(b))
#define GetAuditFuncText	"getaudit_addr"
#define SetAuditFunc(a,b)	setaudit_addr((a),(b))
#define SetAuditFuncText	"setaudit_addr"
#define AUToSubjectFunc		au_to_subject_ex
#define AUToReturnFunc(a,b)	au_to_return32((a), (int32_t)(b))
#else
#define	AuditInfoStruct		auditinfo
#define AuditInfoTermID		au_tid_t
#define GetAuditFunc(a,b)	getaudit(a)
#define GetAuditFuncText	"getaudit"
#define SetAuditFunc(a,b)	setaudit(a)
#define SetAuditFuncText	"setaudit"
#define AUToSubjectFunc		au_to_subject
#define AUToReturnFunc(a,b)	au_to_return((a), (u_int)(b))
#endif

extern int	cannot_audit(int);
extern void	aug_init(void);
extern dev_t	aug_get_port(void);
extern int 	aug_get_machine(char *, u_int32_t *, u_int32_t *);
extern void	aug_save_auid(au_id_t);
extern void	aug_save_uid(uid_t);
extern void	aug_save_euid(uid_t);
extern void	aug_save_gid(gid_t);
extern void	aug_save_egid(gid_t);
extern void	aug_save_pid(pid_t);
extern void	aug_save_asid(au_asid_t);
extern void	aug_save_tid(dev_t, unsigned int);
extern void	aug_save_tid_ex(dev_t, u_int32_t *, u_int32_t);
extern int	aug_save_me(void);
extern int	aug_save_namask(void);
extern void	aug_save_event(au_event_t);
extern void	aug_save_sorf(int);
extern void	aug_save_text(char *);
extern void	aug_save_text1(char *);
extern void	aug_save_text2(char *);
extern void	aug_save_na(int);
extern void	aug_save_user(char *);
extern void	aug_save_path(char *);
extern int	aug_save_policy(void);
extern void	aug_save_afunc(int (*)(int));
extern int	aug_audit(void);
extern int	aug_na_selected(void);
extern int	aug_selected(void);
extern int	aug_daemon_session(void);

#ifndef HAVE_GETTEXT
# define gettext(a)	(a)
#endif

extern Authctxt *the_authctxt;
static AuditInfoTermID ssh_bsm_tid;

/* Below is the low-level BSM interface code */

/*
 * Check if the specified event is selected (enabled) for auditing.
 * Returns 1 if the event is selected, 0 if not and -1 on failure.
 */
static int
selected(char *username, uid_t uid, au_event_t event, int sf)
{
	int rc, sorf;
	char naflags[512];
	struct au_mask mask;

	mask.am_success = mask.am_failure = 0;
	if (uid < 0) {
		/* get flags for non-attributable (to a real user) events */
		rc = getacna(naflags, sizeof(naflags));
		if (rc == 0)
			(void) getauditflagsbin(naflags, &mask);
	} else
		rc = au_user_mask(username, &mask);

	sorf = (sf == 0) ? AU_PRS_SUCCESS : AU_PRS_FAILURE;
	return(au_preselect(event, &mask, sorf, AU_PRS_REREAD));
}

static void
bsm_audit_record(int typ, char *string, au_event_t event_no)
{
	int		ad, rc, sel;
	uid_t		uid = -1;
	gid_t		gid = -1;
	pid_t		pid = getpid();
	AuditInfoTermID	tid = ssh_bsm_tid;

	if (the_authctxt != NULL && the_authctxt->valid) {
		uid = the_authctxt->pw->pw_uid;
		gid = the_authctxt->pw->pw_gid;
	}

	rc = (typ == 0) ? 0 : -1;
	sel = selected(the_authctxt->user, uid, event_no, rc);
	debug3("BSM audit: typ %d rc %d \"%s\"", typ, rc, string);
	if (!sel)
		return;	/* audit event does not match mask, do not write */

	debug3("BSM audit: writing audit new record");
	ad = au_open();

	(void) au_write(ad, AUToSubjectFunc(uid, uid, gid, uid, gid,
	    pid, pid, &tid));
	(void) au_write(ad, au_to_text(string));
	(void) au_write(ad, AUToReturnFunc(typ, rc));

	rc = au_close(ad, AU_TO_WRITE, event_no);
	if (rc < 0)
		error("BSM audit: %s failed to write \"%s\" record: %s",
		    __func__, string, strerror(errno));
}

static void
bsm_audit_session_setup(void)
{
	int rc;
	struct AuditInfoStruct info;
	au_mask_t mask;

	if (the_authctxt == NULL) {
		error("BSM audit: session setup internal error (NULL ctxt)");
		return;
	}

	if (the_authctxt->valid)
		info.ai_auid = the_authctxt->pw->pw_uid;
	else
		info.ai_auid = -1;
	info.ai_asid = getpid();
	mask.am_success = 0;
	mask.am_failure = 0;

	(void) au_user_mask(the_authctxt->user, &mask);

	info.ai_mask.am_success  = mask.am_success;
	info.ai_mask.am_failure  = mask.am_failure;

	info.ai_termid = ssh_bsm_tid;

	rc = SetAuditFunc(&info, sizeof(info));
	if (rc < 0)
		error("BSM audit: %s: %s failed: %s", __func__,
		    SetAuditFuncText, strerror(errno));
}

static void
bsm_audit_bad_login(const char *what)
{
	char textbuf[BSM_TEXTBUFSZ];

	if (the_authctxt->valid) {
		(void) snprintf(textbuf, sizeof (textbuf),
			gettext("invalid %s for user %s"),
			    what, the_authctxt->user);
		bsm_audit_record(4, textbuf, AUE_openssh);
	} else {
		(void) snprintf(textbuf, sizeof (textbuf),
			gettext("invalid user name \"%s\""),
			    the_authctxt->user);
		bsm_audit_record(3, textbuf, AUE_openssh);
	}
}

/* Below is the sshd audit API code */

void
audit_connection_from(const char *host, int port)
{
	AuditInfoTermID *tid = &ssh_bsm_tid;
	char buf[1024];

	if (cannot_audit(0))
		return;
	debug3("BSM audit: connection from %.100s port %d", host, port);

	/* populate our terminal id structure */
#if defined(HAVE_GETAUDIT_ADDR)
	tid->at_port = (dev_t)port;
	aug_get_machine((char *)host, &(tid->at_addr[0]), &(tid->at_type));
	snprintf(buf, sizeof(buf), "%08x %08x %08x %08x", tid->at_addr[0],
	    tid->at_addr[1], tid->at_addr[2], tid->at_addr[3]);
	debug3("BSM audit: iptype %d machine ID %s", (int)tid->at_type, buf);
#else
	/* this is used on IPv4-only machines */
	tid->port = (dev_t)port;
	tid->machine = inet_addr(host);
	snprintf(buf, sizeof(buf), "%08x", tid->machine);
	debug3("BSM audit: machine ID %s", buf);
#endif
}

void
audit_run_command(const char *command)
{
	/* not implemented */
}

void
audit_session_open(const char *ttyn)
{
	/* not implemented */
}

void
audit_session_close(const char *ttyn)
{
	/* not implemented */
}

void
audit_event(ssh_audit_event_t event)
{
	char    textbuf[BSM_TEXTBUFSZ];
	static int logged_in = 0;
	const char *user = the_authctxt ? the_authctxt->user : "(unknown user)";

	if (cannot_audit(0))
		return;

	switch(event) {
	case SSH_AUTH_SUCCESS:
		logged_in = 1;
		bsm_audit_session_setup();
		snprintf(textbuf, sizeof(textbuf),
		    gettext("successful login %s"), user);
		bsm_audit_record(0, textbuf, AUE_openssh);
		break;

	case SSH_CONNECTION_CLOSE:
		/*
		 * We can also get a close event if the user attempted auth
		 * but never succeeded.
		 */
		if (logged_in) {
			snprintf(textbuf, sizeof(textbuf),
			    gettext("sshd logout %s"), the_authctxt->user);
			bsm_audit_record(0, textbuf, AUE_logout);
		} else {
			debug("%s: connection closed without authentication",
			    __func__);
		}
		break;

	case SSH_NOLOGIN:
		bsm_audit_record(1,
		    gettext("logins disabled by /etc/nologin"), AUE_openssh);
		break;

	case SSH_LOGIN_EXCEED_MAXTRIES:
		snprintf(textbuf, sizeof(textbuf),
		    gettext("too many tries for user %s"), the_authctxt->user);
		bsm_audit_record(1, textbuf, AUE_openssh);
		break;

	case SSH_LOGIN_ROOT_DENIED:
		bsm_audit_record(2, gettext("not_console"), AUE_openssh);
		break;

	case SSH_AUTH_FAIL_PASSWD:
		bsm_audit_bad_login("password");
		break;

	case SSH_AUTH_FAIL_KBDINT:
		bsm_audit_bad_login("interactive password entry");
		break;

	default:
		debug("%s: unhandled event %d", __func__, event);
	}
}
#endif /* BSM */