/*
* Copyright (c) 1999-2009 Apple Inc.
* Copyright (c) 2005, 2016-2017 Robert N. M. Watson
* All rights reserved.
*
* Portions of this software were developed by BAE Systems, the University of
* Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
* contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
* Computing (TC) research program.
*
* 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.
* 3. Neither the name of Apple Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "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 APPLE OR ITS CONTRIBUTORS 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/capsicum.h>
#include <sys/fcntl.h>
#include <sys/filedesc.h>
#include <sys/libkern.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/rwlock.h>
#include <sys/sem.h>
#include <sys/sbuf.h>
#include <sys/sx.h>
#include <sys/syscall.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/vnode.h>
#include <bsm/audit.h>
#include <bsm/audit_kevents.h>
#include <security/audit/audit.h>
#include <security/audit/audit_private.h>
/*
* Hash table functions for the audit event number to event class mask
* mapping.
*/
#define EVCLASSMAP_HASH_TABLE_SIZE 251
struct evclass_elem {
au_event_t event;
au_class_t class;
LIST_ENTRY(evclass_elem) entry;
};
struct evclass_list {
LIST_HEAD(, evclass_elem) head;
};
static MALLOC_DEFINE(M_AUDITEVCLASS, "audit_evclass", "Audit event class");
static struct rwlock evclass_lock;
static struct evclass_list evclass_hash[EVCLASSMAP_HASH_TABLE_SIZE];
#define EVCLASS_LOCK_INIT() rw_init(&evclass_lock, "evclass_lock")
#define EVCLASS_RLOCK() rw_rlock(&evclass_lock)
#define EVCLASS_RUNLOCK() rw_runlock(&evclass_lock)
#define EVCLASS_WLOCK() rw_wlock(&evclass_lock)
#define EVCLASS_WUNLOCK() rw_wunlock(&evclass_lock)
/*
* Hash table maintaining a mapping from audit event numbers to audit event
* names. For now, used only by DTrace, but present always so that userspace
* tools can register and inspect fields consistently even if DTrace is not
* present.
*
* struct evname_elem is defined in audit_private.h so that audit_dtrace.c can
* use the definition.
*/
#define EVNAMEMAP_HASH_TABLE_SIZE 251
struct evname_list {
LIST_HEAD(, evname_elem) enl_head;
};
static MALLOC_DEFINE(M_AUDITEVNAME, "audit_evname", "Audit event name");
static struct sx evnamemap_lock;
static struct evname_list evnamemap_hash[EVNAMEMAP_HASH_TABLE_SIZE];
#define EVNAMEMAP_LOCK_INIT() sx_init(&evnamemap_lock, "evnamemap_lock");
#define EVNAMEMAP_RLOCK() sx_slock(&evnamemap_lock)
#define EVNAMEMAP_RUNLOCK() sx_sunlock(&evnamemap_lock)
#define EVNAMEMAP_WLOCK() sx_xlock(&evnamemap_lock)
#define EVNAMEMAP_WUNLOCK() sx_xunlock(&evnamemap_lock)
/*
* Look up the class for an audit event in the class mapping table.
*/
au_class_t
au_event_class(au_event_t event)
{
struct evclass_list *evcl;
struct evclass_elem *evc;
au_class_t class;
EVCLASS_RLOCK();
evcl = &evclass_hash[event % EVCLASSMAP_HASH_TABLE_SIZE];
class = 0;
LIST_FOREACH(evc, &evcl->head, entry) {
if (evc->event == event) {
class = evc->class;
goto out;
}
}
out:
EVCLASS_RUNLOCK();
return (class);
}
/*
* Insert a event to class mapping. If the event already exists in the
* mapping, then replace the mapping with the new one.
*
* XXX There is currently no constraints placed on the number of mappings.
* May want to either limit to a number, or in terms of memory usage.
*/
void
au_evclassmap_insert(au_event_t event, au_class_t class)
{
struct evclass_list *evcl;
struct evclass_elem *evc, *evc_new;
/*
* Pessimistically, always allocate storage before acquiring mutex.
* Free if there is already a mapping for this event.
*/
evc_new = malloc(sizeof(*evc), M_AUDITEVCLASS, M_WAITOK);
EVCLASS_WLOCK();
evcl = &evclass_hash[event % EVCLASSMAP_HASH_TABLE_SIZE];
LIST_FOREACH(evc, &evcl->head, entry) {
if (evc->event == event) {
evc->class = class;
EVCLASS_WUNLOCK();
free(evc_new, M_AUDITEVCLASS);
return;
}
}
evc = evc_new;
evc->event = event;
evc->class = class;
LIST_INSERT_HEAD(&evcl->head, evc, entry);
EVCLASS_WUNLOCK();
}
void
au_evclassmap_init(void)
{
int i;
EVCLASS_LOCK_INIT();
for (i = 0; i < EVCLASSMAP_HASH_TABLE_SIZE; i++)
LIST_INIT(&evclass_hash[i].head);
/*
* Set up the initial event to class mapping for system calls.
*
* XXXRW: Really, this should walk all possible audit events, not all
* native ABI system calls, as there may be audit events reachable
* only through non-native system calls. It also seems a shame to
* frob the mutex this early.
*/
for (i = 0; i < SYS_MAXSYSCALL; i++) {
if (sysent[i].sy_auevent != AUE_NULL)
au_evclassmap_insert(sysent[i].sy_auevent, 0);
}
}
/*
* Look up the name for an audit event in the event-to-name mapping table.
*/
int
au_event_name(au_event_t event, char *name)
{
struct evname_list *enl;
struct evname_elem *ene;
int error;
error = ENOENT;
EVNAMEMAP_RLOCK();
enl = &evnamemap_hash[event % EVNAMEMAP_HASH_TABLE_SIZE];
LIST_FOREACH(ene, &enl->enl_head, ene_entry) {
if (ene->ene_event == event) {
strlcpy(name, ene->ene_name, EVNAMEMAP_NAME_SIZE);
error = 0;
goto out;
}
}
out:
EVNAMEMAP_RUNLOCK();
return (error);
}
/*
* Insert a event-to-name mapping. If the event already exists in the
* mapping, then replace the mapping with the new one.
*
* XXX There is currently no constraints placed on the number of mappings.
* May want to either limit to a number, or in terms of memory usage.
*
* XXXRW: Accepts truncated name -- but perhaps should return failure instead?
*
* XXXRW: It could be we need a way to remove existing names...?
*
* XXXRW: We handle collisions between numbers, but I wonder if we also need a
* way to handle name collisions, for DTrace, where probe names must be
* unique?
*/
void
au_evnamemap_insert(au_event_t event, const char *name)
{
struct evname_list *enl;
struct evname_elem *ene, *ene_new;
/*
* Pessimistically, always allocate storage before acquiring lock.
* Free if there is already a mapping for this event.
*/
ene_new = malloc(sizeof(*ene_new), M_AUDITEVNAME, M_WAITOK | M_ZERO);
EVNAMEMAP_WLOCK();
enl = &evnamemap_hash[event % EVNAMEMAP_HASH_TABLE_SIZE];
LIST_FOREACH(ene, &enl->enl_head, ene_entry) {
if (ene->ene_event == event) {
EVNAME_LOCK(ene);
(void)strlcpy(ene->ene_name, name,
sizeof(ene->ene_name));
EVNAME_UNLOCK(ene);
EVNAMEMAP_WUNLOCK();
free(ene_new, M_AUDITEVNAME);
return;
}
}
ene = ene_new;
mtx_init(&ene->ene_lock, "au_evnamemap", NULL, MTX_DEF);
ene->ene_event = event;
(void)strlcpy(ene->ene_name, name, sizeof(ene->ene_name));
LIST_INSERT_HEAD(&enl->enl_head, ene, ene_entry);
EVNAMEMAP_WUNLOCK();
}
void
au_evnamemap_init(void)
{
int i;
EVNAMEMAP_LOCK_INIT();
for (i = 0; i < EVNAMEMAP_HASH_TABLE_SIZE; i++)
LIST_INIT(&evnamemap_hash[i].enl_head);
/*
* XXXRW: Unlike the event-to-class mapping, we don't attempt to
* pre-populate the list. Perhaps we should...? But not sure we
* really want to duplicate /etc/security/audit_event in the kernel
* -- and we'd need a way to remove names?
*/
}
/*
* The DTrace audit provider occasionally needs to walk the entries in the
* event-to-name mapping table, and uses this public interface to do so. A
* write lock is acquired so that the provider can safely update its fields in
* table entries.
*/
void
au_evnamemap_foreach(au_evnamemap_callback_t callback)
{
struct evname_list *enl;
struct evname_elem *ene;
int i;
EVNAMEMAP_WLOCK();
for (i = 0; i < EVNAMEMAP_HASH_TABLE_SIZE; i++) {
enl = &evnamemap_hash[i];
LIST_FOREACH(ene, &enl->enl_head, ene_entry)
callback(ene);
}
EVNAMEMAP_WUNLOCK();
}
#ifdef KDTRACE_HOOKS
/*
* Look up an event-to-name mapping table entry by event number. As evname
* elements are stable in memory, we can return the pointer without the table
* lock held -- but the caller will need to lock the element mutex before
* accessing element fields.
*
* NB: the event identifier in elements is stable and can be read without
* holding the evname_elem lock.
*/
struct evname_elem *
au_evnamemap_lookup(au_event_t event)
{
struct evname_list *enl;
struct evname_elem *ene;
EVNAMEMAP_RLOCK();
enl = &evnamemap_hash[event % EVNAMEMAP_HASH_TABLE_SIZE];
LIST_FOREACH(ene, &enl->enl_head, ene_entry) {
if (ene->ene_event == event)
goto out;
}
ene = NULL;
out:
EVNAMEMAP_RUNLOCK();
return (ene);
}
#endif /* !KDTRACE_HOOKS */
