/* * Copyright (c) 1999-2005 Apple Computer, 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 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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"); /* * 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; /* * 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; 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. */ cru2x(td->td_ucred, &ar->k_ar.ar_subj_cred); ar->k_ar.ar_subj_ruid = td->td_ucred->cr_ruid; ar->k_ar.ar_subj_rgid = td->td_ucred->cr_rgid; ar->k_ar.ar_subj_egid = td->td_ucred->cr_groups[0]; ar->k_ar.ar_subj_auid = td->td_ucred->cr_audit.ai_auid; ar->k_ar.ar_subj_asid = td->td_ucred->cr_audit.ai_asid; ar->k_ar.ar_subj_pid = td->td_proc->p_pid; ar->k_ar.ar_subj_amask = td->td_ucred->cr_audit.ai_mask; ar->k_ar.ar_subj_term_addr = td->td_ucred->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); } /* * 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) { printf("Security auditing service present\n"); 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 = AU_NULL; audit_nae_mask.am_failure = AU_NULL; 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; mtx_init(&audit_mtx, "audit_mtx", NULL, MTX_DEF); 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. */ 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; switch(ar->k_ar.ar_event) { case AUE_OPEN_RWTC: /* * The open syscall always writes a AUE_OPEN_RWTC event; * change it to the proper type of event based on the flags * and the error value. */ ar->k_ar.ar_event = flags_and_error_to_openevent( ar->k_ar.ar_arg_fflags, error); break; case AUE_SYSCTL: ar->k_ar.ar_event = 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")); /* * 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); } else if (audit_pipe_preselect(auid, event, class, AU_PRS_BOTH, 0)) td->td_ar = audit_new(event, td); 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; } 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; } void audit_cred_proc1(struct ucred *cred) { cred->cr_audit.ai_auid = AU_DEFAUDITID; } 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")); }