| 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.c |
/*-
* Copyright (c) 1999-2005 Apple Inc.
* Copyright (c) 2006-2007 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.c 219028 2011-02-25 10:11:01Z netchild $");
#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/priv.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/sysctl.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>
FEATURE(audit, "BSM audit support");
static uma_zone_t audit_record_zone;
static MALLOC_DEFINE(M_AUDITCRED, "audit_cred", "Audit cred storage");
MALLOC_DEFINE(M_AUDITDATA, "audit_data", "Audit data storage");
MALLOC_DEFINE(M_AUDITPATH, "audit_path", "Audit path storage");
MALLOC_DEFINE(M_AUDITTEXT, "audit_text", "Audit text storage");
MALLOC_DEFINE(M_AUDITGIDSET, "audit_gidset", "Audit GID set storage");
SYSCTL_NODE(_security, OID_AUTO, audit, CTLFLAG_RW, 0,
"TrustedBSD audit controls");
/*
* Audit control settings that are set/read by system calls and are hence
* non-static.
*
* Define the audit control flags.
*/
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_argv;
int audit_arge;
/*
* Are we currently "failing stop" due to out of disk space?
*/
int audit_in_failure;
/*
* Global audit statistics.
*/
struct audit_fstat audit_fstat;
/*
* Preselection mask for non-attributable events.
*/
struct au_mask audit_nae_mask;
/*
* Mutex to protect global variables shared between various threads and
* processes.
*/
struct mtx audit_mtx;
/*
* Queue of audit records ready for delivery to disk. We insert new records
* at the tail, and remove records from the head. Also, a count of the
* number of records used for checking queue depth. In addition, a counter
* of records that we have allocated but are not yet in the queue, which is
* needed to estimate the total size of the combined set of records
* outstanding in the system.
*/
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;
/*
* 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.
*/
struct cv audit_worker_cv;
/*
* Condition variable to flag when crossing the low watermark, meaning that
* threads blocked due to hitting the high watermark can wake up and continue
* to commit records.
*/
struct cv audit_watermark_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;
/*
* Kernel audit information. This will store the current audit address
* or host information that the kernel will use when it's generating
* audit records. This data is modified by the A_GET{SET}KAUDIT auditon(2)
* command.
*/
static struct auditinfo_addr audit_kinfo;
static struct rwlock audit_kinfo_lock;
#define KINFO_LOCK_INIT() rw_init(&audit_kinfo_lock, \
"audit_kinfo_lock")
#define KINFO_RLOCK() rw_rlock(&audit_kinfo_lock)
#define KINFO_WLOCK() rw_wlock(&audit_kinfo_lock)
#define KINFO_RUNLOCK() rw_runlock(&audit_kinfo_lock)
#define KINFO_WUNLOCK() rw_wunlock(&audit_kinfo_lock)
void
audit_set_kinfo(struct auditinfo_addr *ak)
{
KASSERT(ak->ai_termid.at_type == AU_IPv4 ||
ak->ai_termid.at_type == AU_IPv6,
("audit_set_kinfo: invalid address type"));
KINFO_WLOCK();
audit_kinfo = *ak;
KINFO_WUNLOCK();
}
void
audit_get_kinfo(struct auditinfo_addr *ak)
{
KASSERT(audit_kinfo.ai_termid.at_type == AU_IPv4 ||
audit_kinfo.ai_termid.at_type == AU_IPv6,
("audit_set_kinfo: invalid address type"));
KINFO_RLOCK();
*ak = audit_kinfo;
KINFO_RUNLOCK();
}
/*
* Construct an audit record for the passed thread.
*/
static int
audit_record_ctor(void *mem, int size, void *arg, int flags)
{
struct kaudit_record *ar;
struct thread *td;
struct ucred *cred;
KASSERT(sizeof(*ar) == size, ("audit_record_ctor: wrong size"));
td = arg;
ar = mem;
bzero(ar, sizeof(*ar));
ar->k_ar.ar_magic = AUDIT_RECORD_MAGIC;
nanotime(&ar->k_ar.ar_starttime);
/*
* Export the subject credential.
*/
cred = td->td_ucred;
cru2x(cred, &ar->k_ar.ar_subj_cred);
ar->k_ar.ar_subj_ruid = cred->cr_ruid;
ar->k_ar.ar_subj_rgid = cred->cr_rgid;
ar->k_ar.ar_subj_egid = cred->cr_groups[0];
ar->k_ar.ar_subj_auid = cred->cr_audit.ai_auid;
ar->k_ar.ar_subj_asid = cred->cr_audit.ai_asid;
ar->k_ar.ar_subj_pid = td->td_proc->p_pid;
ar->k_ar.ar_subj_amask = cred->cr_audit.ai_mask;
ar->k_ar.ar_subj_term_addr = cred->cr_audit.ai_termid;
return (0);
}
static void
audit_record_dtor(void *mem, int size, void *arg)
{
struct kaudit_record *ar;
KASSERT(sizeof(*ar) == size, ("audit_record_dtor: wrong size"));
ar = mem;
if (ar->k_ar.ar_arg_upath1 != NULL)
free(ar->k_ar.ar_arg_upath1, M_AUDITPATH);
if (ar->k_ar.ar_arg_upath2 != NULL)
free(ar->k_ar.ar_arg_upath2, M_AUDITPATH);
if (ar->k_ar.ar_arg_text != NULL)
free(ar->k_ar.ar_arg_text, M_AUDITTEXT);
if (ar->k_udata != NULL)
free(ar->k_udata, M_AUDITDATA);
if (ar->k_ar.ar_arg_argv != NULL)
free(ar->k_ar.ar_arg_argv, M_AUDITTEXT);
if (ar->k_ar.ar_arg_envv != NULL)
free(ar->k_ar.ar_arg_envv, M_AUDITTEXT);
if (ar->k_ar.ar_arg_groups.gidset != NULL)
free(ar->k_ar.ar_arg_groups.gidset, M_AUDITGIDSET);
}
/*
* Initialize the Audit subsystem: configuration state, work queue,
* synchronization primitives, worker thread, and trigger device node. Also
* call into the BSM assembly code to initialize it.
*/
static void
audit_init(void)
{
audit_enabled = 0;
audit_suspended = 0;
audit_panic_on_write_fail = 0;
audit_fail_stop = 0;
audit_in_failure = 0;
audit_argv = 0;
audit_arge = 0;
audit_fstat.af_filesz = 0; /* '0' means unset, unbounded. */
audit_fstat.af_currsz = 0;
audit_nae_mask.am_success = 0;
audit_nae_mask.am_failure = 0;
TAILQ_INIT(&audit_q);
audit_q_len = 0;
audit_pre_q_len = 0;
audit_qctrl.aq_hiwater = AQ_HIWATER;
audit_qctrl.aq_lowater = AQ_LOWATER;
audit_qctrl.aq_bufsz = AQ_BUFSZ;
audit_qctrl.aq_minfree = AU_FS_MINFREE;
audit_kinfo.ai_termid.at_type = AU_IPv4;
audit_kinfo.ai_termid.at_addr[0] = INADDR_ANY;
mtx_init(&audit_mtx, "audit_mtx", NULL, MTX_DEF);
KINFO_LOCK_INIT();
cv_init(&audit_worker_cv, "audit_worker_cv");
cv_init(&audit_watermark_cv, "audit_watermark_cv");
cv_init(&audit_fail_cv, "audit_fail_cv");
audit_record_zone = uma_zcreate("audit_record",
sizeof(struct kaudit_record), audit_record_ctor,
audit_record_dtor, NULL, NULL, UMA_ALIGN_PTR, 0);
/* Initialize the BSM audit subsystem. */
kau_init();
audit_trigger_init();
/* Register shutdown handler. */
EVENTHANDLER_REGISTER(shutdown_pre_sync, audit_shutdown, NULL,
SHUTDOWN_PRI_FIRST);
/* Start audit worker thread. */
audit_worker_init();
}
SYSINIT(audit_init, SI_SUB_AUDIT, SI_ORDER_FIRST, audit_init, NULL);
/*
* 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
* configuration syscalls, so 'arg' and 'howto' are ignored.
*
* XXXRW: In FreeBSD 7.x and 8.x, this fails to wait for the record queue to
* drain before returning, which could lead to lost records on shutdown.
*/
void
audit_shutdown(void *arg, int howto)
{
audit_rotate_vnode(NULL, NULL);
}
/*
* Return the current thread's audit record, if any.
*/
struct kaudit_record *
currecord(void)
{
return (curthread->td_ar);
}
/*
* XXXAUDIT: There are a number of races present in the code below due to
* release and re-grab of the mutex. The code should be revised to become
* slightly less racy.
*
* XXXAUDIT: Shouldn't there be logic here to sleep waiting on available
* pre_q space, suspending the system call until there is room?
*/
struct kaudit_record *
audit_new(int event, struct thread *td)
{
struct kaudit_record *ar;
int no_record;
mtx_lock(&audit_mtx);
no_record = (audit_suspended || !audit_enabled);
mtx_unlock(&audit_mtx);
if (no_record)
return (NULL);
/*
* Note: the number of outstanding uncommitted audit records is
* limited to the number of concurrent threads servicing system calls
* in the kernel.
*/
ar = uma_zalloc_arg(audit_record_zone, td, M_WAITOK);
ar->k_ar.ar_event = event;
mtx_lock(&audit_mtx);
audit_pre_q_len++;
mtx_unlock(&audit_mtx);
return (ar);
}
void
audit_free(struct kaudit_record *ar)
{
uma_zfree(audit_record_zone, ar);
}
void
audit_commit(struct kaudit_record *ar, int error, int retval)
{
au_event_t event;
au_class_t class;
au_id_t auid;
int sorf;
struct au_mask *aumask;
if (ar == NULL)
return;
/*
* Decide whether to commit the audit record by checking the error
* value from the system call and using the appropriate audit mask.
*/
if (ar->k_ar.ar_subj_auid == AU_DEFAUDITID)
aumask = &audit_nae_mask;
else
aumask = &ar->k_ar.ar_subj_amask;
if (error)
sorf = AU_PRS_FAILURE;
else
sorf = AU_PRS_SUCCESS;
/*
* syscalls.master sometimes contains a prototype event number, which
* we will transform into a more specific event number now that we
* have more complete information gathered during the system call.
*/
switch(ar->k_ar.ar_event) {
case AUE_OPEN_RWTC:
ar->k_ar.ar_event = audit_flags_and_error_to_openevent(
ar->k_ar.ar_arg_fflags, error);
break;
case AUE_OPENAT_RWTC:
ar->k_ar.ar_event = audit_flags_and_error_to_openatevent(
ar->k_ar.ar_arg_fflags, error);
break;
case AUE_SYSCTL:
ar->k_ar.ar_event = audit_ctlname_to_sysctlevent(
ar->k_ar.ar_arg_ctlname, ar->k_ar.ar_valid_arg);
break;
case AUE_AUDITON:
/* Convert the auditon() command to an event. */
ar->k_ar.ar_event = auditon_command_event(ar->k_ar.ar_arg_cmd);
break;
}
auid = ar->k_ar.ar_subj_auid;
event = ar->k_ar.ar_event;
class = au_event_class(event);
ar->k_ar_commit |= AR_COMMIT_KERNEL;
if (au_preselect(event, class, aumask, sorf) != 0)
ar->k_ar_commit |= AR_PRESELECT_TRAIL;
if (audit_pipe_preselect(auid, event, class, sorf,
ar->k_ar_commit & AR_PRESELECT_TRAIL) != 0)
ar->k_ar_commit |= AR_PRESELECT_PIPE;
if ((ar->k_ar_commit & (AR_PRESELECT_TRAIL | AR_PRESELECT_PIPE |
AR_PRESELECT_USER_TRAIL | AR_PRESELECT_USER_PIPE)) == 0) {
mtx_lock(&audit_mtx);
audit_pre_q_len--;
mtx_unlock(&audit_mtx);
audit_free(ar);
return;
}
ar->k_ar.ar_errno = error;
ar->k_ar.ar_retval = retval;
nanotime(&ar->k_ar.ar_endtime);
/*
* Note: it could be that some records initiated while audit was
* enabled should still be committed?
*/
mtx_lock(&audit_mtx);
if (audit_suspended || !audit_enabled) {
audit_pre_q_len--;
mtx_unlock(&audit_mtx);
audit_free(ar);
return;
}
/*
* Constrain the number of committed audit records based on the
* configurable parameter.
*/
while (audit_q_len >= audit_qctrl.aq_hiwater)
cv_wait(&audit_watermark_cv, &audit_mtx);
TAILQ_INSERT_TAIL(&audit_q, ar, k_q);
audit_q_len++;
audit_pre_q_len--;
cv_signal(&audit_worker_cv);
mtx_unlock(&audit_mtx);
}
/*
* audit_syscall_enter() is called on entry to each system call. It is
* responsible for deciding whether or not to audit the call (preselection),
* and if so, allocating a per-thread audit record. audit_new() will fill in
* basic thread/credential properties.
*/
void
audit_syscall_enter(unsigned short code, struct thread *td)
{
struct au_mask *aumask;
au_class_t class;
au_event_t event;
au_id_t auid;
KASSERT(td->td_ar == NULL, ("audit_syscall_enter: td->td_ar != NULL"));
KASSERT((td->td_pflags & TDP_AUDITREC) == 0,
("audit_syscall_enter: TDP_AUDITREC set"));
/*
* In FreeBSD, each ABI has its own system call table, and hence
* mapping of system call codes to audit events. Convert the code to
* an audit event identifier using the process system call table
* reference. In Darwin, there's only one, so we use the global
* symbol for the system call table. No audit record is generated
* for bad system calls, as no operation has been performed.
*/
if (code >= td->td_proc->p_sysent->sv_size)
return;
event = td->td_proc->p_sysent->sv_table[code].sy_auevent;
if (event == AUE_NULL)
return;
/*
* Check which audit mask to use; either the kernel non-attributable
* event mask or the process audit mask.
*/
auid = td->td_ucred->cr_audit.ai_auid;
if (auid == AU_DEFAUDITID)
aumask = &audit_nae_mask;
else
aumask = &td->td_ucred->cr_audit.ai_mask;
/*
* Allocate an audit record, if preselection allows it, and store in
* the thread for later use.
*/
class = au_event_class(event);
if (au_preselect(event, class, aumask, AU_PRS_BOTH)) {
/*
* If we're out of space and need to suspend unprivileged
* processes, do that here rather than trying to allocate
* another audit record.
*
* Note: we might wish to be able to continue here in the
* future, if the system recovers. That should be possible
* by means of checking the condition in a loop around
* cv_wait(). It might be desirable to reevaluate whether an
* audit record is still required for this event by
* re-calling au_preselect().
*/
if (audit_in_failure &&
priv_check(td, PRIV_AUDIT_FAILSTOP) != 0) {
cv_wait(&audit_fail_cv, &audit_mtx);
panic("audit_failing_stop: thread continued");
}
td->td_ar = audit_new(event, td);
if (td->td_ar != NULL)
td->td_pflags |= TDP_AUDITREC;
} else if (audit_pipe_preselect(auid, event, class, AU_PRS_BOTH, 0)) {
td->td_ar = audit_new(event, td);
if (td->td_ar != NULL)
td->td_pflags |= TDP_AUDITREC;
} else
td->td_ar = NULL;
}
/*
* audit_syscall_exit() is called from the return of every system call, or in
* the event of exit1(), during the execution of exit1(). It is responsible
* for committing the audit record, if any, along with return condition.
*/
void
audit_syscall_exit(int error, struct thread *td)
{
int retval;
/*
* Commit the audit record as desired; once we pass the record into
* audit_commit(), the memory is owned by the audit subsystem. The
* return value from the system call is stored on the user thread.
* If there was an error, the return value is set to -1, imitating
* the behavior of the cerror routine.
*/
if (error)
retval = -1;
else
retval = td->td_retval[0];
audit_commit(td->td_ar, error, retval);
td->td_ar = NULL;
td->td_pflags &= ~TDP_AUDITREC;
}
void
audit_cred_copy(struct ucred *src, struct ucred *dest)
{
bcopy(&src->cr_audit, &dest->cr_audit, sizeof(dest->cr_audit));
}
void
audit_cred_destroy(struct ucred *cred)
{
}
void
audit_cred_init(struct ucred *cred)
{
bzero(&cred->cr_audit, sizeof(cred->cr_audit));
}
/*
* Initialize audit information for the first kernel process (proc 0) and for
* the first user process (init).
*/
void
audit_cred_kproc0(struct ucred *cred)
{
cred->cr_audit.ai_auid = AU_DEFAUDITID;
cred->cr_audit.ai_termid.at_type = AU_IPv4;
}
void
audit_cred_proc1(struct ucred *cred)
{
cred->cr_audit.ai_auid = AU_DEFAUDITID;
cred->cr_audit.ai_termid.at_type = AU_IPv4;
}
void
audit_thread_alloc(struct thread *td)
{
td->td_ar = NULL;
}
void
audit_thread_free(struct thread *td)
{
KASSERT(td->td_ar == NULL, ("audit_thread_free: td_ar != NULL"));
KASSERT((td->td_pflags & TDP_AUDITREC) == 0,
("audit_thread_free: TDP_AUDITREC set"));
}
void
audit_proc_coredump(struct thread *td, char *path, int errcode)
{
struct kaudit_record *ar;
struct au_mask *aumask;
struct ucred *cred;
au_class_t class;
int ret, sorf;
char **pathp;
au_id_t auid;
ret = 0;
/*
* Make sure we are using the correct preselection mask.
*/
cred = td->td_ucred;
auid = cred->cr_audit.ai_auid;
if (auid == AU_DEFAUDITID)
aumask = &audit_nae_mask;
else
aumask = &cred->cr_audit.ai_mask;
/*
* It's possible for coredump(9) generation to fail. Make sure that
* we handle this case correctly for preselection.
*/
if (errcode != 0)
sorf = AU_PRS_FAILURE;
else
sorf = AU_PRS_SUCCESS;
class = au_event_class(AUE_CORE);
if (au_preselect(AUE_CORE, class, aumask, sorf) == 0 &&
audit_pipe_preselect(auid, AUE_CORE, class, sorf, 0) == 0)
return;
/*
* If we are interested in seeing this audit record, allocate it.
* Where possible coredump records should contain a pathname and arg32
* (signal) tokens.
*/
ar = audit_new(AUE_CORE, td);
if (path != NULL) {
pathp = &ar->k_ar.ar_arg_upath1;
*pathp = malloc(MAXPATHLEN, M_AUDITPATH, M_WAITOK);
audit_canon_path(td, path, *pathp);
ARG_SET_VALID(ar, ARG_UPATH1);
}
ar->k_ar.ar_arg_signum = td->td_proc->p_sig;
ARG_SET_VALID(ar, ARG_SIGNUM);
if (errcode != 0)
ret = 1;
audit_commit(ar, errcode, ret);
}