mirror/freebsd
1
0
Fork 0
mirror of https://git.FreeBSD.org/src.git synced 2024-12-13 10:02:38 +00:00
Code Issues Releases Activity

Merge Perforce changes 93512, 93514, 93515 from TrustedBSD audit3

Browse Source 
branch:

  Integrate audit.c to audit_worker.c, so as to migrate the worker
  thread implementation to its own .c file.

  Populate audit_worker.c using parts now removed from audit.c:

  - Move audit rotation global variables.
  - Move audit_record_write(), audit_worker_rotate(),
    audit_worker_drain(), audit_worker(), audit_rotate_vnode().
  - Create audit_worker_init() from relevant parts of audit_init(),
    which now calls this routine.
  - Recreate audit_free(), which wraps uma_zfree() so that
    audit_record_zone can be static to audit.c.
  - Unstaticize various types and variables relating to the audit
    record queue so that audit_worker can get to them.  We may want
    to wrap these in accessor methods at some point.
  - Move AUDIT_PRINTF() to audit_private.h.

  Addition of audit_worker.c to kernel configuration, missed in
  earlier submit.

Obtained from:	TrustedBSD Project
This commit is contained in:
Robert Watson 2006-03-19 16:03:43 +00:00
parent ccade99c75
commit 08e57af45b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=156888
4 changed files with 619 additions and 497 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
sys/conf/files
View File

@ -1843,6 +1843,7 @@ security/audit/audit_bsm_token.c optional audit
security/audit/audit_pipe.c optional audit
security/audit/audit_syscalls.c standard
security/audit/audit_trigger.c optional audit
security/audit/audit_worker.c optional audit
security/mac/mac_inet.c optional mac inet
security/mac/mac_label.c optional mac
security/mac/mac_net.c optional mac

523
sys/security/audit/audit.c
View File

@ -69,20 +69,7 @@
#include <vm/uma.h>
/*
* The AUDIT_EXCESSIVELY_VERBOSE define enables a number of
* gratuitously noisy printf's to the console. Due to the
* volume, it should be left off unless you want your system
* to churn a lot whenever the audit record flow gets high.
*/
//#define AUDIT_EXCESSIVELY_VERBOSE
#ifdef AUDIT_EXCESSIVELY_VERBOSE
#define AUDIT_PRINTF(x) printf x
#else
#define AUDIT_PRINTF(X)
#endif
static uma_zone_t audit_record_zone;
static uma_zone_t audit_record_zone;
static MALLOC_DEFINE(M_AUDITPROC, "audit_proc", "Audit process storage");
MALLOC_DEFINE(M_AUDITDATA, "audit_data", "Audit data storage");
MALLOC_DEFINE(M_AUDITPATH, "audit_path", "Audit path storage");
@ -95,37 +82,37 @@ MALLOC_DEFINE(M_AUDITTEXT, "audit_text", "Audit text storage");
/*
* Define the audit control flags.
*/
int audit_enabled;
int audit_suspended;
int audit_enabled;
int audit_suspended;
/*
* Flags controlling behavior in low storage situations.
* Should we panic if a write fails? Should we fail stop
* if we're out of disk space?
*/
int audit_panic_on_write_fail;
int audit_fail_stop;
int audit_panic_on_write_fail;
int audit_fail_stop;
/*
* Are we currently "failing stop" due to out of disk space?
*/
static int audit_in_failure;
int audit_in_failure;
/*
* Global audit statistiscs.
*/
struct audit_fstat audit_fstat;
struct audit_fstat audit_fstat;
/*
* Preselection mask for non-attributable events.
*/
struct au_mask audit_nae_mask;
struct au_mask audit_nae_mask;
/*
* Mutex to protect global variables shared between various threads and
* processes.
*/
static struct mtx audit_mtx;
struct mtx audit_mtx;
/*
* Queue of audit records ready for delivery to disk. We insert new
@ -135,67 +122,37 @@ static struct mtx audit_mtx;
* not yet in the queue, which is needed to estimate the total
* size of the combined set of records outstanding in the system.
*/
static TAILQ_HEAD(, kaudit_record) audit_q;
static int audit_q_len;
static int audit_pre_q_len;
struct kaudit_queue audit_q;
int audit_q_len;
int audit_pre_q_len;
/*
* Audit queue control settings (minimum free, low/high water marks, etc.)
*/
struct au_qctrl audit_qctrl;
struct au_qctrl audit_qctrl;
/*
* Condition variable to signal to the worker that it has work to do:
* either new records are in the queue, or a log replacement is taking
* place.
*/
static struct cv audit_cv;
struct cv audit_cv;
/*
* Worker thread that will schedule disk I/O, etc.
*/
static struct proc *audit_thread;
/*
* When an audit log is rotated, the actual rotation must be performed
* by the audit worker thread, as it may have outstanding writes on the
* current audit log. audit_replacement_vp holds the vnode replacing
* the current vnode. We can't let more than one replacement occur
* at a time, so if more than one thread requests a replacement, only
* one can have the replacement "in progress" at any given moment. If
* a thread tries to replace the audit vnode and discovers a replacement
* is already in progress (i.e., audit_replacement_flag != 0), then it
* will sleep on audit_replacement_cv waiting its turn to perform a
* replacement. When a replacement is completed, this cv is signalled
* by the worker thread so a waiting thread can start another replacement.
* We also store a credential to perform audit log write operations with.
* Condition variable to signal to the worker that it has work to do:
* either new records are in the queue, or a log replacement is taking
* place.
*
* The current credential and vnode are thread-local to audit_worker.
* XXXRW: This description is incorrect.
*/
static struct cv audit_replacement_cv;
static int audit_replacement_flag;
static struct vnode *audit_replacement_vp;
static struct ucred *audit_replacement_cred;
/*
* Condition variable to signal to the worker that it has work to do:
* either new records are in the queue, or a log replacement is taking
* place.
*/
static struct cv audit_commit_cv;
struct cv audit_commit_cv;
/*
* Condition variable for auditing threads wait on when in fail-stop mode.
* Threads wait on this CV forever (and ever), never seeing the light of
* day again.
*/
static struct cv audit_fail_cv;
/*
* Flags related to Kernel->user-space communication.
*/
static int audit_file_rotate_wait;
static struct cv audit_fail_cv;
/*
* Construct an audit record for the passed thread.
@ -252,365 +209,6 @@ audit_record_dtor(void *mem, int size, void *arg)
free(ar->k_udata, M_AUDITDATA);
}
/*
* XXXAUDIT: Should adjust comments below to make it clear that we get to
* this point only if we believe we have storage, so not having space here
* is a violation of invariants derived from administrative procedures.
* I.e., someone else has written to the audit partition, leaving less space
* than we accounted for.
*/
static int
audit_record_write(struct vnode *vp, struct kaudit_record *ar,
struct ucred *cred, struct thread *td)
{
int ret;
long temp;
struct au_record *bsm;
struct vattr vattr;
struct statfs *mnt_stat = &vp->v_mount->mnt_stat;
int vfslocked;
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. In both cases,
* if we're unable to perform the operation, we drop the record
* and return. However, this is arguably an assertion failure.
* XXX Need a FreeBSD equivalent.
*/
ret = VFS_STATFS(vp->v_mount, mnt_stat, td);
if (ret)
goto out;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
ret = VOP_GETATTR(vp, &vattr, cred, td);
VOP_UNLOCK(vp, 0, td);
if (ret)
goto out;
/* update the global stats struct */
audit_fstat.af_currsz = vattr.va_size;
/*
* XXX Need to decide what to do if the trigger to the audit daemon
* fails.
*/
/*
* If we fall below minimum free blocks (hard limit), tell the audit
* daemon to force a rotation off of the file system. We also stop
* writing, which means this audit record is probably lost.
* If we fall below the minimum percent free blocks (soft limit),
* then kindly suggest to the audit daemon to do something.
*/
if (mnt_stat->f_bfree < AUDIT_HARD_LIMIT_FREE_BLOCKS) {
(void)send_trigger(AUDIT_TRIGGER_NO_SPACE);
/* Hopefully userspace did something about all the previous
* triggers that were sent prior to this critical condition.
* If fail-stop is set, then we're done; goodnight Gracie.
*/
if (audit_fail_stop)
panic("Audit log space exhausted and fail-stop set.");
else {
audit_suspended = 1;
ret = ENOSPC;
goto out;
}
} else
/*
* Send a message to the audit daemon that disk space
* is getting low.
*
* XXXAUDIT: Check math and block size calculation here.
*/
if (audit_qctrl.aq_minfree != 0) {
temp = mnt_stat->f_blocks / (100 /
audit_qctrl.aq_minfree);
if (mnt_stat->f_bfree < temp)
(void)send_trigger(AUDIT_TRIGGER_LOW_SPACE);
}
/* Check if the current log file is full; if so, call for
* a log rotate. This is not an exact comparison; we may
* write some records over the limit. If that's not
* acceptable, then add a fudge factor here.
*/
if ((audit_fstat.af_filesz != 0) &&
(audit_file_rotate_wait == 0) &&
(vattr.va_size >= audit_fstat.af_filesz)) {
audit_file_rotate_wait = 1;
(void)send_trigger(AUDIT_TRIGGER_OPEN_NEW);
}
/*
* 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 packets 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 &&
(unsigned long)
((audit_q_len + audit_pre_q_len + 1) * MAX_AUDIT_RECORD_SIZE) /
mnt_stat->f_bsize >= (unsigned long)(mnt_stat->f_bfree)) {
printf("audit_record_write: free space below size of audit "
"queue, failing stop\n");
audit_in_failure = 1;
}
/*
* If there is a user audit record attached to the kernel record,
* then write the user record.
*/
/* XXX Need to decide a few things here: IF the user audit
* record is written, but the write of the kernel record fails,
* what to do? Should the kernel record come before or after the
* user record? For now, we write the user record first, and
* we ignore errors.
*/
if (ar->k_ar_commit & AR_COMMIT_USER) {
/*
* Try submitting the record to any active audit pipes.
*/
audit_pipe_submit((void *)ar->k_udata, ar->k_ulen);
/*
* And to disk.
*/
ret = vn_rdwr(UIO_WRITE, vp, (void *)ar->k_udata, ar->k_ulen,
(off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, cred, NULL,
NULL, td);
if (ret)
goto out;
}
/*
* Convert the internal kernel record to BSM format and write it
* out if everything's OK.
*/
if (!(ar->k_ar_commit & AR_COMMIT_KERNEL)) {
ret = 0;
goto out;
}
/*
* XXXAUDIT: Should we actually allow this conversion to fail? With
* sleeping memory allocation and invariants checks, perhaps not.
*/
ret = kaudit_to_bsm(ar, &bsm);
if (ret == BSM_NOAUDIT) {
ret = 0;
goto out;
}
/*
* XXX: We drop the record on BSM conversion failure, but really
* this is an assertion failure.
*/
if (ret == BSM_FAILURE) {
AUDIT_PRINTF(("BSM conversion failure\n"));
ret = EINVAL;
goto out;
}
/*
* Try submitting the record to any active audit pipes.
*/
audit_pipe_submit((void *)bsm->data, bsm->len);
/*
* XXX
* We should break the write functionality away from the BSM record
* generation and have the BSM generation done before this function
* is called. This function will then take the BSM record as a
* parameter.
*/
ret = (vn_rdwr(UIO_WRITE, vp, (void *)bsm->data, bsm->len,
(off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, cred, NULL, NULL, td));
kau_free(bsm);
out:
/*
* When we're done processing the current record, we have to
* check to see if we're in a failure mode, and if so, whether
* this was the last record left to be drained. If we're done
* draining, then we fsync the vnode and panic.
*/
if (audit_in_failure &&
audit_q_len == 0 && audit_pre_q_len == 0) {
VOP_LOCK(vp, LK_DRAIN | LK_INTERLOCK, td);
(void)VOP_FSYNC(vp, MNT_WAIT, td);
VOP_UNLOCK(vp, 0, td);
panic("Audit store overflow; record queue drained.");
}
VFS_UNLOCK_GIANT(vfslocked);
return (ret);
}
/*
* 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. In addition, the audit_work performs the
* actual exchange of audit log vnode pointer, as audit_vp is a thread-local
* variable.
*/
static void
audit_worker(void *arg)
{
int do_replacement_signal, error;
TAILQ_HEAD(, kaudit_record) ar_worklist;
struct kaudit_record *ar;
struct vnode *audit_vp, *old_vp;
int vfslocked;
struct ucred *audit_cred, *old_cred;
struct thread *audit_td;
AUDIT_PRINTF(("audit_worker starting\n"));
/*
* These are thread-local variables requiring no synchronization.
*/
TAILQ_INIT(&ar_worklist);
audit_cred = NULL;
audit_td = curthread;
audit_vp = NULL;
mtx_lock(&audit_mtx);
while (1) {
/*
* First priority: replace the audit log target if requested.
* Accessing the vnode here requires dropping the audit_mtx;
* in case another replacement was scheduled while the mutex
* was released, we loop.
*
* XXX It could well be we should drain existing records
* first to ensure that the timestamps and ordering
* are right.
*/
do_replacement_signal = 0;
while (audit_replacement_flag != 0) {
old_cred = audit_cred;
old_vp = audit_vp;
audit_cred = audit_replacement_cred;
audit_vp = audit_replacement_vp;
audit_replacement_cred = NULL;
audit_replacement_vp = NULL;
audit_replacement_flag = 0;
audit_enabled = (audit_vp != NULL);
/*
* XXX: What to do about write failures here?
*/
if (old_vp != NULL) {
AUDIT_PRINTF(("Closing old audit file\n"));
mtx_unlock(&audit_mtx);
vfslocked = VFS_LOCK_GIANT(old_vp->v_mount);
vn_close(old_vp, AUDIT_CLOSE_FLAGS, old_cred,
audit_td);
VFS_UNLOCK_GIANT(vfslocked);
crfree(old_cred);
mtx_lock(&audit_mtx);
old_cred = NULL;
old_vp = NULL;
AUDIT_PRINTF(("Audit file closed\n"));
}
if (audit_vp != NULL) {
AUDIT_PRINTF(("Opening new audit file\n"));
}
do_replacement_signal = 1;
}
/*
* Signal that replacement have occurred to wake up and
* start any other replacements started in parallel. We can
* continue about our business in the mean time. We
* broadcast so that both new replacements can be inserted,
* but also so that the source(s) of replacement can return
* successfully.
*/
if (do_replacement_signal)
cv_broadcast(&audit_replacement_cv);
/*
* Next, check to see if we have any records to drain into
* the vnode. If not, go back to waiting for an event.
*/
if (TAILQ_EMPTY(&audit_q)) {
AUDIT_PRINTF(("audit_worker waiting\n"));
cv_wait(&audit_cv, &audit_mtx);
AUDIT_PRINTF(("audit_worker woken up\n"));
AUDIT_PRINTF(("audit_worker: new vp = %p; value of flag %d\n",
audit_replacement_vp, audit_replacement_flag));
continue;
}
/*
* If we have records, but there's no active vnode to write
* to, drain the record queue. Generally, we prevent the
* unnecessary allocation of records elsewhere, but we need
* to allow for races between conditional allocation and
* queueing. Go back to waiting when we're done.
*/
if (audit_vp == NULL) {
while ((ar = TAILQ_FIRST(&audit_q))) {
TAILQ_REMOVE(&audit_q, ar, k_q);
uma_zfree(audit_record_zone, ar);
audit_q_len--;
/*
* XXXRW: Why broadcast if we hold the
* mutex and know that audit_vp is NULL?
*/
if (audit_q_len <= audit_qctrl.aq_lowater)
cv_broadcast(&audit_commit_cv);
}
continue;
}
/*
* We have both records to write and an active vnode to write
* to. Dequeue a record, and start the write. Eventually,
* it might make sense to dequeue several records and perform
* our own clustering, if the lower layers aren't doing it
* automatically enough.
*/
while ((ar = TAILQ_FIRST(&audit_q))) {
TAILQ_REMOVE(&audit_q, ar, k_q);
audit_q_len--;
if (audit_q_len <= audit_qctrl.aq_lowater)
cv_broadcast(&audit_commit_cv);
TAILQ_INSERT_TAIL(&ar_worklist, ar, k_q);
}
mtx_unlock(&audit_mtx);
while ((ar = TAILQ_FIRST(&ar_worklist))) {
TAILQ_REMOVE(&ar_worklist, ar, k_q);
if (audit_vp != NULL) {
error = audit_record_write(audit_vp, ar,
audit_cred, audit_td);
if (error && audit_panic_on_write_fail)
panic("audit_worker: write error %d\n",
error);
else if (error)
printf("audit_worker: write error %d\n",
error);
}
uma_zfree(audit_record_zone, ar);
}
mtx_lock(&audit_mtx);
}
}
/*
* Initialize the Audit subsystem: configuration state, work queue,
* synchronization primitives, worker thread, and trigger device node. Also
@ -619,7 +217,6 @@ audit_worker(void *arg)
static void
audit_init(void)
{
int error;
printf("Security auditing service present\n");
audit_enabled = 0;
@ -628,10 +225,6 @@ audit_init(void)
audit_fail_stop = 0;
audit_in_failure = 0;
audit_replacement_vp = NULL;
audit_replacement_cred = NULL;
audit_replacement_flag = 0;
audit_fstat.af_filesz = 0; /* '0' means unset, unbounded */
audit_fstat.af_currsz = 0;
audit_nae_mask.am_success = AU_NULL;
@ -647,7 +240,6 @@ audit_init(void)
mtx_init(&audit_mtx, "audit_mtx", NULL, MTX_DEF);
cv_init(&audit_cv, "audit_cv");
cv_init(&audit_replacement_cv, "audit_replacement_cv");
cv_init(&audit_commit_cv, "audit_commit_cv");
cv_init(&audit_fail_cv, "audit_fail_cv");
@ -658,82 +250,18 @@ audit_init(void)
/* Initialize the BSM audit subsystem. */
kau_init();
audit_file_rotate_wait = 0;
audit_trigger_init();
/* Register shutdown handler. */
EVENTHANDLER_REGISTER(shutdown_pre_sync, audit_shutdown, NULL,
SHUTDOWN_PRI_FIRST);
error = kthread_create(audit_worker, NULL, &audit_thread, RFHIGHPID,
0, "audit_worker");
if (error != 0)
panic("audit_init: kthread_create returned %d", error);
/* Start audit worker thread. */
audit_worker_init();
}
SYSINIT(audit_init, SI_SUB_AUDIT, SI_ORDER_FIRST, audit_init, NULL)
/*
* 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 and vnode 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. The real work is done in the
* audit_worker thread, but audit_rotate_vnode() waits synchronously for that
* to complete.
*
* The vnode should be referenced and opened by the caller. The credential
* should be referenced. audit_rotate_vnode() will own both references as of
* this call, so the caller should not release either.
*
* XXXAUDIT: Review synchronize communication logic. Really, this is a
* message queue of depth 1.
*
* XXXAUDIT: Enhance the comments below to indicate that we are basically
* acquiring ownership of the communications queue, inserting our message,
* and waiting for an acknowledgement.
*/
void
audit_rotate_vnode(struct ucred *cred, struct vnode *vp)
{
/*
* If other parallel log replacements have been requested, we wait
* until they've finished before continuing.
*/
mtx_lock(&audit_mtx);
while (audit_replacement_flag != 0) {
AUDIT_PRINTF(("audit_rotate_vnode: sleeping to wait for "
"flag\n"));
cv_wait(&audit_replacement_cv, &audit_mtx);
AUDIT_PRINTF(("audit_rotate_vnode: woken up (flag %d)\n",
audit_replacement_flag));
}
audit_replacement_cred = cred;
audit_replacement_flag = 1;
audit_replacement_vp = vp;
/*
* Wake up the audit worker to perform the exchange once we
* release the mutex.
*/
cv_signal(&audit_cv);
/*
* Wait for the audit_worker to broadcast that a replacement has
* taken place; we know that once this has happened, our vnode
* has been replaced in, so we can return successfully.
*/
AUDIT_PRINTF(("audit_rotate_vnode: waiting for news of "
"replacement\n"));
cv_wait(&audit_replacement_cv, &audit_mtx);
AUDIT_PRINTF(("audit_rotate_vnode: change acknowledged by "
"audit_worker (flag " "now %d)\n", audit_replacement_flag));
mtx_unlock(&audit_mtx);
audit_file_rotate_wait = 0; /* We can now request another rotation */
}
/*
* Drain the audit queue and close the log at shutdown. Note that this can
* be called both from the system shutdown path and also from audit
@ -793,6 +321,13 @@ audit_new(int event, struct thread *td)
return (ar);
}
void
audit_free(struct kaudit_record *ar)
{
uma_zfree(audit_record_zone, ar);
}
/*
* MPSAFE
*/

34
sys/security/audit/audit_private.h
View File

@ -52,6 +52,19 @@ MALLOC_DECLARE(M_AUDITPATH);
MALLOC_DECLARE(M_AUDITTEXT);
#endif
/*
* The AUDIT_EXCESSIVELY_VERBOSE define enables a number of gratuitously
* noisy printf's to the console. Due to the volume, it should be left off
* unless you want your system to churn a lot whenever the audit record flow
* gets high.
*/
//#define AUDIT_EXCESSIVELY_VERBOSE
#ifdef AUDIT_EXCESSIVELY_VERBOSE
#define AUDIT_PRINTF(x) printf x
#else
#define AUDIT_PRINTF(x)
#endif
/*
* Audit control variables that are usually set/read via system calls
* and used to control various aspects of auditing.
@ -213,19 +226,20 @@ struct audit_record {
*/
struct kaudit_record {
struct audit_record k_ar;
u_int32_t k_ar_commit;
u_int32_t k_ar_commit;
void *k_udata; /* user data */
u_int k_ulen; /* user data length */
struct uthread *k_uthread; /* thread we are auditing */
TAILQ_ENTRY(kaudit_record) k_q;
};
TAILQ_HEAD(kaudit_queue, kaudit_record);
/*
* Functions to manage the allocation, release, and commit of kernel audit
* records.
*/
void audit_abort(struct kaudit_record *ar);
void audit_commit(struct kaudit_record *ar, int error,
void audit_commit(struct kaudit_record *ar, int error,
int retval);
struct kaudit_record *audit_new(int event, struct thread *td);
@ -251,7 +265,19 @@ void kau_init(void);
#define AU_PRS_FAILURE 2
#define AU_PRS_BOTH (AU_PRS_SUCCESS|AU_PRS_FAILURE)
/*
/*
* Data structures relating to the kernel audit queue. Ideally, these might
* be abstracted so that only accessor methods are exposed.
*/
extern struct mtx audit_mtx;
extern struct cv audit_commit_cv;
extern struct cv audit_cv;
extern struct kaudit_queue audit_q;
extern int audit_q_len;
extern int audit_pre_q_len;
extern int audit_in_failure;
/*
* Flags to use on audit files when opening and closing.
*/
#define AUDIT_OPEN_FLAGS (FWRITE | O_APPEND)
@ -293,9 +319,11 @@ int send_trigger(unsigned int trigger);
* General audit related functions.
*/
struct kaudit_record *currecord(void);
void audit_free(struct kaudit_record *ar);
void audit_shutdown(void *arg, int howto);
void audit_rotate_vnode(struct ucred *cred,
struct vnode *vp);
void audit_worker_init(void);
/*
* Audit pipe functions.

558
sys/security/audit/audit_worker.c Normal file
View File

@ -0,0 +1,558 @@
/*
* Copyright (c) 1999-2005 Apple Computer, Inc.
* Copyright (c) 2006 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 Computer, 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.
*
* $FreeBSD$
*/
#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/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;
/*
* When an audit log is rotated, the actual rotation must be performed
* by the audit worker thread, as it may have outstanding writes on the
* current audit log. audit_replacement_vp holds the vnode replacing
* the current vnode. We can't let more than one replacement occur
* at a time, so if more than one thread requests a replacement, only
* one can have the replacement "in progress" at any given moment. If
* a thread tries to replace the audit vnode and discovers a replacement
* is already in progress (i.e., audit_replacement_flag != 0), then it
* will sleep on audit_replacement_cv waiting its turn to perform a
* replacement. When a replacement is completed, this cv is signalled
* by the worker thread so a waiting thread can start another replacement.
* We also store a credential to perform audit log write operations with.
*
* The current credential and vnode are thread-local to audit_worker.
*/
static struct cv audit_replacement_cv;
static int audit_replacement_flag;
static struct vnode *audit_replacement_vp;
static struct ucred *audit_replacement_cred;
/*
* Flags related to Kernel->user-space communication.
*/
static int audit_file_rotate_wait;
/*
* XXXAUDIT: Should adjust comments below to make it clear that we get to
* this point only if we believe we have storage, so not having space here
* is a violation of invariants derived from administrative procedures.
* I.e., someone else has written to the audit partition, leaving less space
* than we accounted for.
*/
static int
audit_record_write(struct vnode *vp, struct kaudit_record *ar,
struct ucred *cred, struct thread *td)
{
int ret;
long temp;
struct au_record *bsm;
struct vattr vattr;
struct statfs *mnt_stat = &vp->v_mount->mnt_stat;
int vfslocked;
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. In both cases,
* if we're unable to perform the operation, we drop the record
* and return. However, this is arguably an assertion failure.
* XXX Need a FreeBSD equivalent.
*/
ret = VFS_STATFS(vp->v_mount, mnt_stat, td);
if (ret)
goto out;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
ret = VOP_GETATTR(vp, &vattr, cred, td);
VOP_UNLOCK(vp, 0, td);
if (ret)
goto out;
/* update the global stats struct */
audit_fstat.af_currsz = vattr.va_size;
/*
* XXX Need to decide what to do if the trigger to the audit daemon
* fails.
*/
/*
* If we fall below minimum free blocks (hard limit), tell the audit
* daemon to force a rotation off of the file system. We also stop
* writing, which means this audit record is probably lost.
* If we fall below the minimum percent free blocks (soft limit),
* then kindly suggest to the audit daemon to do something.
*/
if (mnt_stat->f_bfree < AUDIT_HARD_LIMIT_FREE_BLOCKS) {
(void)send_trigger(AUDIT_TRIGGER_NO_SPACE);
/* Hopefully userspace did something about all the previous
* triggers that were sent prior to this critical condition.
* If fail-stop is set, then we're done; goodnight Gracie.
*/
if (audit_fail_stop)
panic("Audit log space exhausted and fail-stop set.");
else {
audit_suspended = 1;
ret = ENOSPC;
goto out;
}
} else
/*
* Send a message to the audit daemon that disk space
* is getting low.
*
* XXXAUDIT: Check math and block size calculation here.
*/
if (audit_qctrl.aq_minfree != 0) {
temp = mnt_stat->f_blocks / (100 /
audit_qctrl.aq_minfree);
if (mnt_stat->f_bfree < temp)
(void)send_trigger(AUDIT_TRIGGER_LOW_SPACE);
}
/* Check if the current log file is full; if so, call for
* a log rotate. This is not an exact comparison; we may
* write some records over the limit. If that's not
* acceptable, then add a fudge factor here.
*/
if ((audit_fstat.af_filesz != 0) &&
(audit_file_rotate_wait == 0) &&
(vattr.va_size >= audit_fstat.af_filesz)) {
audit_file_rotate_wait = 1;
(void)send_trigger(AUDIT_TRIGGER_OPEN_NEW);
}
/*
* 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 packets 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 &&
(unsigned long)
((audit_q_len + audit_pre_q_len + 1) * MAX_AUDIT_RECORD_SIZE) /
mnt_stat->f_bsize >= (unsigned long)(mnt_stat->f_bfree)) {
printf("audit_record_write: free space below size of audit "
"queue, failing stop\n");
audit_in_failure = 1;
}
/*
* If there is a user audit record attached to the kernel record,
* then write the user record.
*/
/* XXX Need to decide a few things here: IF the user audit
* record is written, but the write of the kernel record fails,
* what to do? Should the kernel record come before or after the
* user record? For now, we write the user record first, and
* we ignore errors.
*/
if (ar->k_ar_commit & AR_COMMIT_USER) {
/*
* Try submitting the record to any active audit pipes.
*/
audit_pipe_submit((void *)ar->k_udata, ar->k_ulen);
/*
* And to disk.
*/
ret = vn_rdwr(UIO_WRITE, vp, (void *)ar->k_udata, ar->k_ulen,
(off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, cred, NULL,
NULL, td);
if (ret)
goto out;
}
/*
* Convert the internal kernel record to BSM format and write it
* out if everything's OK.
*/
if (!(ar->k_ar_commit & AR_COMMIT_KERNEL)) {
ret = 0;
goto out;
}
/*
* XXXAUDIT: Should we actually allow this conversion to fail? With
* sleeping memory allocation and invariants checks, perhaps not.
*/
ret = kaudit_to_bsm(ar, &bsm);
if (ret == BSM_NOAUDIT) {
ret = 0;
goto out;
}
/*
* XXX: We drop the record on BSM conversion failure, but really
* this is an assertion failure.
*/
if (ret == BSM_FAILURE) {
AUDIT_PRINTF(("BSM conversion failure\n"));
ret = EINVAL;
goto out;
}
/*
* Try submitting the record to any active audit pipes.
*/
audit_pipe_submit((void *)bsm->data, bsm->len);
/*
* XXX
* We should break the write functionality away from the BSM record
* generation and have the BSM generation done before this function
* is called. This function will then take the BSM record as a
* parameter.
*/
ret = (vn_rdwr(UIO_WRITE, vp, (void *)bsm->data, bsm->len,
(off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, cred, NULL, NULL, td));
kau_free(bsm);
out:
/*
* When we're done processing the current record, we have to
* check to see if we're in a failure mode, and if so, whether
* this was the last record left to be drained. If we're done
* draining, then we fsync the vnode and panic.
*/
if (audit_in_failure &&
audit_q_len == 0 && audit_pre_q_len == 0) {
VOP_LOCK(vp, LK_DRAIN | LK_INTERLOCK, td);
(void)VOP_FSYNC(vp, MNT_WAIT, td);
VOP_UNLOCK(vp, 0, td);
panic("Audit store overflow; record queue drained.");
}
VFS_UNLOCK_GIANT(vfslocked);
return (ret);
}
/*
* If an appropriate signal has been received rotate the audit log based on
* the global replacement variables. Signal consumers as needed that the
* rotation has taken place.
*
* XXXRW: The global variables and CVs used to signal the audit_worker to
* perform a rotation are essentially a message queue of depth 1. It would
* be much nicer to actually use a message queue.
*/
static void
audit_worker_rotate(struct ucred **audit_credp, struct vnode **audit_vpp,
struct thread *audit_td)
{
int do_replacement_signal, vfslocked;
struct ucred *old_cred;
struct vnode *old_vp;
mtx_assert(&audit_mtx, MA_OWNED);
do_replacement_signal = 0;
while (audit_replacement_flag != 0) {
old_cred = *audit_credp;
old_vp = *audit_vpp;
*audit_credp = audit_replacement_cred;
*audit_vpp = audit_replacement_vp;
audit_replacement_cred = NULL;
audit_replacement_vp = NULL;
audit_replacement_flag = 0;
audit_enabled = (*audit_vpp != NULL);
/*
* XXX: What to do about write failures here?
*/
if (old_vp != NULL) {
AUDIT_PRINTF(("Closing old audit file\n"));
mtx_unlock(&audit_mtx);
vfslocked = VFS_LOCK_GIANT(old_vp->v_mount);
vn_close(old_vp, AUDIT_CLOSE_FLAGS, old_cred,
audit_td);
VFS_UNLOCK_GIANT(vfslocked);
crfree(old_cred);
mtx_lock(&audit_mtx);
old_cred = NULL;
old_vp = NULL;
AUDIT_PRINTF(("Audit file closed\n"));
}
if (*audit_vpp != NULL) {
AUDIT_PRINTF(("Opening new audit file\n"));
}
do_replacement_signal = 1;
}
/*
* Signal that replacement have occurred to wake up and
* start any other replacements started in parallel. We can
* continue about our business in the mean time. We
* broadcast so that both new replacements can be inserted,
* but also so that the source(s) of replacement can return
* successfully.
*/
if (do_replacement_signal)
cv_broadcast(&audit_replacement_cv);
}
/*
* Drain the audit commit queue and free the records. Used if there are
* records present, but no audit log target.
*/
static void
audit_worker_drain(void)
{
struct kaudit_record *ar;
while ((ar = TAILQ_FIRST(&audit_q))) {
TAILQ_REMOVE(&audit_q, ar, k_q);
audit_free(ar);
audit_q_len--;
}
}
/*
* 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. In addition, the audit_work performs the
* actual exchange of audit log vnode pointer, as audit_vp is a thread-local
* variable.
*/
static void
audit_worker(void *arg)
{
TAILQ_HEAD(, kaudit_record) ar_worklist;
struct kaudit_record *ar;
struct ucred *audit_cred;
struct thread *audit_td;
struct vnode *audit_vp;
int error, lowater_signal;
AUDIT_PRINTF(("audit_worker starting\n"));
/*
* These are thread-local variables requiring no synchronization.
*/
TAILQ_INIT(&ar_worklist);
audit_cred = NULL;
audit_td = curthread;
audit_vp = NULL;
mtx_lock(&audit_mtx);
while (1) {
mtx_assert(&audit_mtx, MA_OWNED);
/*
* Wait for record or rotation events.
*/
while (!audit_replacement_flag && TAILQ_EMPTY(&audit_q)) {
AUDIT_PRINTF(("audit_worker waiting\n"));
cv_wait(&audit_cv, &audit_mtx);
AUDIT_PRINTF(("audit_worker woken up\n"));
AUDIT_PRINTF(("audit_worker: new vp = %p; value of "
"flag %d\n", audit_replacement_vp,
audit_replacement_flag));
}
/*
* First priority: replace the audit log target if requested.
*/
audit_worker_rotate(&audit_cred, &audit_vp, audit_td);
/*
* If we have records, but there's no active vnode to write
* to, drain the record queue. Generally, we prevent the
* unnecessary allocation of records elsewhere, but we need
* to allow for races between conditional allocation and
* queueing. Go back to waiting when we're done.
*/
if (audit_vp == NULL) {
audit_worker_drain();
continue;
}
/*
* We have both records to write and an active vnode to write
* to. Dequeue a record, and start the write. Eventually,
* it might make sense to dequeue several records and perform
* our own clustering, if the lower layers aren't doing it
* automatically enough.
*/
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_commit_cv);
mtx_unlock(&audit_mtx);
while ((ar = TAILQ_FIRST(&ar_worklist))) {
TAILQ_REMOVE(&ar_worklist, ar, k_q);
if (audit_vp != NULL) {
error = audit_record_write(audit_vp, ar,
audit_cred, audit_td);
if (error && audit_panic_on_write_fail)
panic("audit_worker: write error %d\n",
error);
else if (error)
printf("audit_worker: write error %d\n",
error);
}
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 and vnode 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. The real work is done in the
* audit_worker thread, but audit_rotate_vnode() waits synchronously for that
* to complete.
*
* The vnode should be referenced and opened by the caller. The credential
* should be referenced. audit_rotate_vnode() will own both references as of
* this call, so the caller should not release either.
*
* XXXAUDIT: Review synchronize communication logic. Really, this is a
* message queue of depth 1.
*
* XXXAUDIT: Enhance the comments below to indicate that we are basically
* acquiring ownership of the communications queue, inserting our message,
* and waiting for an acknowledgement.
*/
void
audit_rotate_vnode(struct ucred *cred, struct vnode *vp)
{
/*
* If other parallel log replacements have been requested, we wait
* until they've finished before continuing.
*/
mtx_lock(&audit_mtx);
while (audit_replacement_flag != 0) {
AUDIT_PRINTF(("audit_rotate_vnode: sleeping to wait for "
"flag\n"));
cv_wait(&audit_replacement_cv, &audit_mtx);
AUDIT_PRINTF(("audit_rotate_vnode: woken up (flag %d)\n",
audit_replacement_flag));
}
audit_replacement_cred = cred;
audit_replacement_flag = 1;
audit_replacement_vp = vp;
/*
* Wake up the audit worker to perform the exchange once we
* release the mutex.
*/
cv_signal(&audit_cv);
/*
* Wait for the audit_worker to broadcast that a replacement has
* taken place; we know that once this has happened, our vnode
* has been replaced in, so we can return successfully.
*/
AUDIT_PRINTF(("audit_rotate_vnode: waiting for news of "
"replacement\n"));
cv_wait(&audit_replacement_cv, &audit_mtx);
AUDIT_PRINTF(("audit_rotate_vnode: change acknowledged by "
"audit_worker (flag " "now %d)\n", audit_replacement_flag));
mtx_unlock(&audit_mtx);
audit_file_rotate_wait = 0; /* We can now request another rotation */
}
void
audit_worker_init(void)
{
int error;
cv_init(&audit_replacement_cv, "audit_replacement_cv");
error = kthread_create(audit_worker, NULL, &audit_thread, RFHIGHPID,
0, "audit_worker");
if (error)
panic("audit_worker_init: kthread_create returned %d", error);
}