| Current Path : /sys/security/audit/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //sys/security/audit/audit_worker.c |
/*-
* Copyright (c) 1999-2008 Apple Inc.
* Copyright (c) 2006-2008 Robert N. M. Watson
* All rights reserved.
*
* 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: release/9.1.0/sys/security/audit/audit_worker.c 191990 2009-05-11 15:33:26Z attilio $");
#include <sys/param.h>
#include <sys/condvar.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/fcntl.h>
#include <sys/ipc.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <sys/domain.h>
#include <sys/sx.h>
#include <sys/sysproto.h>
#include <sys/sysent.h>
#include <sys/systm.h>
#include <sys/ucred.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <bsm/audit.h>
#include <bsm/audit_internal.h>
#include <bsm/audit_kevents.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <security/audit/audit.h>
#include <security/audit/audit_private.h>
#include <vm/uma.h>
/*
* Worker thread that will schedule disk I/O, etc.
*/
static struct proc *audit_thread;
/*
* audit_cred and audit_vp are the stored credential and vnode to use for
* active audit trail. They are protected by the audit worker lock, which
* will be held across all I/O and all rotation to prevent them from being
* replaced (rotated) while in use. The audit_file_rotate_wait flag is set
* when the kernel has delivered a trigger to auditd to rotate the trail, and
* is cleared when the next rotation takes place. It is also protected by
* the audit worker lock.
*/
static int audit_file_rotate_wait;
static struct ucred *audit_cred;
static struct vnode *audit_vp;
static struct sx audit_worker_lock;
#define AUDIT_WORKER_LOCK_INIT() sx_init(&audit_worker_lock, \
"audit_worker_lock");
#define AUDIT_WORKER_LOCK_ASSERT() sx_assert(&audit_worker_lock, \
SA_XLOCKED)
#define AUDIT_WORKER_LOCK() sx_xlock(&audit_worker_lock)
#define AUDIT_WORKER_UNLOCK() sx_xunlock(&audit_worker_lock)
/*
* Write an audit record to a file, performed as the last stage after both
* preselection and BSM conversion. Both space management and write failures
* are handled in this function.
*
* No attempt is made to deal with possible failure to deliver a trigger to
* the audit daemon, since the message is asynchronous anyway.
*/
static void
audit_record_write(struct vnode *vp, struct ucred *cred, void *data,
size_t len)
{
static struct timeval last_lowspace_trigger;
static struct timeval last_fail;
static int cur_lowspace_trigger;
struct statfs *mnt_stat;
int error, vfslocked;
static int cur_fail;
struct vattr vattr;
long temp;
AUDIT_WORKER_LOCK_ASSERT();
if (vp == NULL)
return;
mnt_stat = &vp->v_mount->mnt_stat;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
/*
* First, gather statistics on the audit log file and file system so
* that we know how we're doing on space. Consider failure of these
* operations to indicate a future inability to write to the file.
*/
error = VFS_STATFS(vp->v_mount, mnt_stat);
if (error)
goto fail;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
error = VOP_GETATTR(vp, &vattr, cred);
VOP_UNLOCK(vp, 0);
if (error)
goto fail;
audit_fstat.af_currsz = vattr.va_size;
/*
* We handle four different space-related limits:
*
* - A fixed (hard) limit on the minimum free blocks we require on
* the file system, and results in record loss, a trigger, and
* possible fail stop due to violating invariants.
*
* - An administrative (soft) limit, which when fallen below, results
* in the kernel notifying the audit daemon of low space.
*
* - An audit trail size limit, which when gone above, results in the
* kernel notifying the audit daemon that rotation is desired.
*
* - The total depth of the kernel audit record exceeding free space,
* which can lead to possible fail stop (with drain), in order to
* prevent violating invariants. Failure here doesn't halt
* immediately, but prevents new records from being generated.
*
* Possibly, the last of these should be handled differently, always
* allowing a full queue to be lost, rather than trying to prevent
* loss.
*
* First, handle the hard limit, which generates a trigger and may
* fail stop. This is handled in the same manner as ENOSPC from
* VOP_WRITE, and results in record loss.
*/
if (mnt_stat->f_bfree < AUDIT_HARD_LIMIT_FREE_BLOCKS) {
error = ENOSPC;
goto fail_enospc;
}
/*
* Second, handle falling below the soft limit, if defined; we send
* the daemon a trigger and continue processing the record. Triggers
* are limited to 1/sec.
*/
if (audit_qctrl.aq_minfree != 0) {
temp = mnt_stat->f_blocks / (100 / audit_qctrl.aq_minfree);
if (mnt_stat->f_bfree < temp) {
if (ppsratecheck(&last_lowspace_trigger,
&cur_lowspace_trigger, 1)) {
(void)audit_send_trigger(
AUDIT_TRIGGER_LOW_SPACE);
printf("Warning: disk space low (< %d%% free) "
"on audit log file-system\n",
audit_qctrl.aq_minfree);
}
}
}
/*
* If the current file is getting full, generate a rotation trigger
* to the daemon. This is only approximate, which is fine as more
* records may be generated before the daemon rotates the file.
*/
if ((audit_fstat.af_filesz != 0) && (audit_file_rotate_wait == 0) &&
(vattr.va_size >= audit_fstat.af_filesz)) {
AUDIT_WORKER_LOCK_ASSERT();
audit_file_rotate_wait = 1;
(void)audit_send_trigger(AUDIT_TRIGGER_ROTATE_KERNEL);
}
/*
* If the estimated amount of audit data in the audit event queue
* (plus records allocated but not yet queued) has reached the amount
* of free space on the disk, then we need to go into an audit fail
* stop state, in which we do not permit the allocation/committing of
* any new audit records. We continue to process records but don't
* allow any activities that might generate new records. In the
* future, we might want to detect when space is available again and
* allow operation to continue, but this behavior is sufficient to
* meet fail stop requirements in CAPP.
*/
if (audit_fail_stop) {
if ((unsigned long)((audit_q_len + audit_pre_q_len + 1) *
MAX_AUDIT_RECORD_SIZE) / mnt_stat->f_bsize >=
(unsigned long)(mnt_stat->f_bfree)) {
if (ppsratecheck(&last_fail, &cur_fail, 1))
printf("audit_record_write: free space "
"below size of audit queue, failing "
"stop\n");
audit_in_failure = 1;
} else if (audit_in_failure) {
/*
* Note: if we want to handle recovery, this is the
* spot to do it: unset audit_in_failure, and issue a
* wakeup on the cv.
*/
}
}
error = vn_rdwr(UIO_WRITE, vp, data, len, (off_t)0, UIO_SYSSPACE,
IO_APPEND|IO_UNIT, cred, NULL, NULL, curthread);
if (error == ENOSPC)
goto fail_enospc;
else if (error)
goto fail;
/*
* Catch completion of a queue drain here; if we're draining and the
* queue is now empty, fail stop. That audit_fail_stop is implicitly
* true, since audit_in_failure can only be set of audit_fail_stop is
* set.
*
* Note: if we handle recovery from audit_in_failure, then we need to
* make panic here conditional.
*/
if (audit_in_failure) {
if (audit_q_len == 0 && audit_pre_q_len == 0) {
VOP_LOCK(vp, LK_EXCLUSIVE | LK_RETRY);
(void)VOP_FSYNC(vp, MNT_WAIT, curthread);
VOP_UNLOCK(vp, 0);
panic("Audit store overflow; record queue drained.");
}
}
VFS_UNLOCK_GIANT(vfslocked);
return;
fail_enospc:
/*
* ENOSPC is considered a special case with respect to failures, as
* this can reflect either our preemptive detection of insufficient
* space, or ENOSPC returned by the vnode write call.
*/
if (audit_fail_stop) {
VOP_LOCK(vp, LK_EXCLUSIVE | LK_RETRY);
(void)VOP_FSYNC(vp, MNT_WAIT, curthread);
VOP_UNLOCK(vp, 0);
panic("Audit log space exhausted and fail-stop set.");
}
(void)audit_send_trigger(AUDIT_TRIGGER_NO_SPACE);
audit_suspended = 1;
/* FALLTHROUGH */
fail:
/*
* We have failed to write to the file, so the current record is
* lost, which may require an immediate system halt.
*/
if (audit_panic_on_write_fail) {
VOP_LOCK(vp, LK_EXCLUSIVE | LK_RETRY);
(void)VOP_FSYNC(vp, MNT_WAIT, curthread);
VOP_UNLOCK(vp, 0);
panic("audit_worker: write error %d\n", error);
} else if (ppsratecheck(&last_fail, &cur_fail, 1))
printf("audit_worker: write error %d\n", error);
VFS_UNLOCK_GIANT(vfslocked);
}
/*
* Given a kernel audit record, process as required. Kernel audit records
* are converted to one, or possibly two, BSM records, depending on whether
* there is a user audit record present also. Kernel records need be
* converted to BSM before they can be written out. Both types will be
* written to disk, and audit pipes.
*/
static void
audit_worker_process_record(struct kaudit_record *ar)
{
struct au_record *bsm;
au_class_t class;
au_event_t event;
au_id_t auid;
int error, sorf;
int locked;
/*
* We hold the audit worker lock over both writes, if there are two,
* so that the two records won't be split across a rotation and end
* up in two different trail files.
*/
if (((ar->k_ar_commit & AR_COMMIT_USER) &&
(ar->k_ar_commit & AR_PRESELECT_USER_TRAIL)) ||
(ar->k_ar_commit & AR_PRESELECT_TRAIL)) {
AUDIT_WORKER_LOCK();
locked = 1;
} else
locked = 0;
/*
* First, handle the user record, if any: commit to the system trail
* and audit pipes as selected.
*/
if ((ar->k_ar_commit & AR_COMMIT_USER) &&
(ar->k_ar_commit & AR_PRESELECT_USER_TRAIL)) {
AUDIT_WORKER_LOCK_ASSERT();
audit_record_write(audit_vp, audit_cred, ar->k_udata,
ar->k_ulen);
}
if ((ar->k_ar_commit & AR_COMMIT_USER) &&
(ar->k_ar_commit & AR_PRESELECT_USER_PIPE))
audit_pipe_submit_user(ar->k_udata, ar->k_ulen);
if (!(ar->k_ar_commit & AR_COMMIT_KERNEL) ||
((ar->k_ar_commit & AR_PRESELECT_PIPE) == 0 &&
(ar->k_ar_commit & AR_PRESELECT_TRAIL) == 0))
goto out;
auid = ar->k_ar.ar_subj_auid;
event = ar->k_ar.ar_event;
class = au_event_class(event);
if (ar->k_ar.ar_errno == 0)
sorf = AU_PRS_SUCCESS;
else
sorf = AU_PRS_FAILURE;
error = kaudit_to_bsm(ar, &bsm);
switch (error) {
case BSM_NOAUDIT:
goto out;
case BSM_FAILURE:
printf("audit_worker_process_record: BSM_FAILURE\n");
goto out;
case BSM_SUCCESS:
break;
default:
panic("kaudit_to_bsm returned %d", error);
}
if (ar->k_ar_commit & AR_PRESELECT_TRAIL) {
AUDIT_WORKER_LOCK_ASSERT();
audit_record_write(audit_vp, audit_cred, bsm->data, bsm->len);
}
if (ar->k_ar_commit & AR_PRESELECT_PIPE)
audit_pipe_submit(auid, event, class, sorf,
ar->k_ar_commit & AR_PRESELECT_TRAIL, bsm->data,
bsm->len);
kau_free(bsm);
out:
if (locked)
AUDIT_WORKER_UNLOCK();
}
/*
* The audit_worker thread is responsible for watching the event queue,
* dequeueing records, converting them to BSM format, and committing them to
* disk. In order to minimize lock thrashing, records are dequeued in sets
* to a thread-local work queue.
*
* Note: this means that the effect bound on the size of the pending record
* queue is 2x the length of the global queue.
*/
static void
audit_worker(void *arg)
{
struct kaudit_queue ar_worklist;
struct kaudit_record *ar;
int lowater_signal;
TAILQ_INIT(&ar_worklist);
mtx_lock(&audit_mtx);
while (1) {
mtx_assert(&audit_mtx, MA_OWNED);
/*
* Wait for a record.
*/
while (TAILQ_EMPTY(&audit_q))
cv_wait(&audit_worker_cv, &audit_mtx);
/*
* If there are records in the global audit record queue,
* transfer them to a thread-local queue and process them
* one by one. If we cross the low watermark threshold,
* signal any waiting processes that they may wake up and
* continue generating records.
*/
lowater_signal = 0;
while ((ar = TAILQ_FIRST(&audit_q))) {
TAILQ_REMOVE(&audit_q, ar, k_q);
audit_q_len--;
if (audit_q_len == audit_qctrl.aq_lowater)
lowater_signal++;
TAILQ_INSERT_TAIL(&ar_worklist, ar, k_q);
}
if (lowater_signal)
cv_broadcast(&audit_watermark_cv);
mtx_unlock(&audit_mtx);
while ((ar = TAILQ_FIRST(&ar_worklist))) {
TAILQ_REMOVE(&ar_worklist, ar, k_q);
audit_worker_process_record(ar);
audit_free(ar);
}
mtx_lock(&audit_mtx);
}
}
/*
* audit_rotate_vnode() is called by a user or kernel thread to configure or
* de-configure auditing on a vnode. The arguments are the replacement
* credential (referenced) and vnode (referenced and opened) to substitute
* for the current credential and vnode, if any. If either is set to NULL,
* both should be NULL, and this is used to indicate that audit is being
* disabled. Any previous cred/vnode will be closed and freed. We re-enable
* generating rotation requests to auditd.
*/
void
audit_rotate_vnode(struct ucred *cred, struct vnode *vp)
{
struct ucred *old_audit_cred;
struct vnode *old_audit_vp;
int vfslocked;
KASSERT((cred != NULL && vp != NULL) || (cred == NULL && vp == NULL),
("audit_rotate_vnode: cred %p vp %p", cred, vp));
/*
* Rotate the vnode/cred, and clear the rotate flag so that we will
* send a rotate trigger if the new file fills.
*/
AUDIT_WORKER_LOCK();
old_audit_cred = audit_cred;
old_audit_vp = audit_vp;
audit_cred = cred;
audit_vp = vp;
audit_file_rotate_wait = 0;
audit_enabled = (audit_vp != NULL);
AUDIT_WORKER_UNLOCK();
/*
* If there was an old vnode/credential, close and free.
*/
if (old_audit_vp != NULL) {
vfslocked = VFS_LOCK_GIANT(old_audit_vp->v_mount);
vn_close(old_audit_vp, AUDIT_CLOSE_FLAGS, old_audit_cred,
curthread);
VFS_UNLOCK_GIANT(vfslocked);
crfree(old_audit_cred);
}
}
void
audit_worker_init(void)
{
int error;
AUDIT_WORKER_LOCK_INIT();
error = kproc_create(audit_worker, NULL, &audit_thread, RFHIGHPID,
0, "audit");
if (error)
panic("audit_worker_init: kproc_create returned %d", error);
}