/*- * Copyright (c) 1999-2009 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. * */ /* * NOTICE: This file was modified by McAfee Research in 2004 to introduce * support for mandatory and extensible security protections. This notice * is included in support of clause 2.2 (b) of the Apple Public License, * Version 2.0. */ #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 #include #include #include #include #include #include #include #include #if CONFIG_AUDIT 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; int audit_syscalls; au_class_t audit_kevent_mask; /* * 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 signal when the worker is done draining the audit * queue. */ struct cv audit_drain_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; static zone_t audit_record_zone; /* * 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(); bcopy(ak, &audit_kinfo, sizeof(audit_kinfo)); 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(); bcopy(&audit_kinfo, ak, sizeof(*ak)); KINFO_RUNLOCK(); } /* * Construct an audit record for the passed thread. */ static void audit_record_ctor(proc_t p, struct kaudit_record *ar) { kauth_cred_t cred; bzero(ar, sizeof(*ar)); ar->k_ar.ar_magic = AUDIT_RECORD_MAGIC; nanotime(&ar->k_ar.ar_starttime); if (PROC_NULL != p) { cred = kauth_cred_proc_ref(p); /* * Export the subject credential. */ cru2x(cred, &ar->k_ar.ar_subj_cred); ar->k_ar.ar_subj_ruid = kauth_cred_getruid(cred); ar->k_ar.ar_subj_rgid = kauth_cred_getrgid(cred); ar->k_ar.ar_subj_egid = kauth_cred_getgid(cred); ar->k_ar.ar_subj_pid = p->p_pid; ar->k_ar.ar_subj_auid = cred->cr_audit.as_aia_p->ai_auid; ar->k_ar.ar_subj_asid = cred->cr_audit.as_aia_p->ai_asid; bcopy(&cred->cr_audit.as_mask, &ar->k_ar.ar_subj_amask, sizeof(struct au_mask)); bcopy(&cred->cr_audit.as_aia_p->ai_termid, &ar->k_ar.ar_subj_term_addr, sizeof(struct au_tid_addr)); kauth_cred_unref(&cred); } } static void audit_record_dtor(struct kaudit_record *ar) { 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_kpath1 != NULL) free(ar->k_ar.ar_arg_kpath1, M_AUDITPATH); if (ar->k_ar.ar_arg_kpath2 != NULL) free(ar->k_ar.ar_arg_kpath2, M_AUDITPATH); if (ar->k_ar.ar_arg_text != NULL) free(ar->k_ar.ar_arg_text, M_AUDITTEXT); if (ar->k_ar.ar_arg_opaque != NULL) free(ar->k_ar.ar_arg_opaque, M_AUDITDATA); if (ar->k_ar.ar_arg_data != NULL) free(ar->k_ar.ar_arg_data, M_AUDITDATA); 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. */ void audit_init(void) { audit_enabled = 0; audit_syscalls = 0; audit_kevent_mask = 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; _audit_lck_grp_init(); mtx_init(&audit_mtx, "audit_mtx", NULL, MTX_DEF); KINFO_LOCK_INIT(); cv_init(&audit_worker_cv, "audit_worker_cv"); cv_init(&audit_drain_cv, "audit_drain_cv"); cv_init(&audit_watermark_cv, "audit_watermark_cv"); cv_init(&audit_fail_cv, "audit_fail_cv"); audit_record_zone = zinit(sizeof(struct kaudit_record), AQ_HIWATER*sizeof(struct kaudit_record), 8192, "audit_zone"); #if CONFIG_MACF audit_mac_init(); #endif /* Init audit session subsystem. */ audit_session_init(); /* Initialize the BSM audit subsystem. */ kau_init(); /* audit_trigger_init(); */ /* Start audit worker thread. */ (void) audit_pipe_init(); /* Start audit worker thread. */ audit_worker_init(); } /* * 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) { audit_rotate_vnode(NULL, NULL); } /* * Return the current thread's audit record, if any. */ struct kaudit_record * currecord(void) { return (curthread()->uu_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, proc_t p, __unused struct uthread *uthread) { struct kaudit_record *ar; int no_record; int audit_override; /* * Override the audit_suspended and audit_enabled if it always * audits session events. * * XXXss - This really needs to be a generalized call to a filter * interface so if other things that use the audit subsystem in the * future can simply plugged in. */ audit_override = (AUE_SESSION_START == event || AUE_SESSION_UPDATE == event || AUE_SESSION_END == event || AUE_SESSION_CLOSE == event); mtx_lock(&audit_mtx); no_record = (audit_suspended || !audit_enabled); mtx_unlock(&audit_mtx); if (!audit_override && no_record) return (NULL); /* * Initialize the audit record header. * XXX: We may want to fail-stop if allocation fails. * * Note: the number of outstanding uncommitted audit records is * limited to the number of concurrent threads servicing system calls * in the kernel. */ ar = zalloc(audit_record_zone); if (ar == NULL) return NULL; audit_record_ctor(p, ar); ar->k_ar.ar_event = event; #if CONFIG_MACF if (PROC_NULL != p) { if (audit_mac_new(p, ar) != 0) { zfree(audit_record_zone, ar); return (NULL); } } else ar->k_ar.ar_mac_records = NULL; #endif mtx_lock(&audit_mtx); audit_pre_q_len++; mtx_unlock(&audit_mtx); return (ar); } void audit_free(struct kaudit_record *ar) { audit_record_dtor(ar); #if CONFIG_MACF if (NULL != ar->k_ar.ar_mac_records) audit_mac_free(ar); #endif 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; int audit_override; 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 = audit_flags_and_error_to_openevent( ar->k_ar.ar_arg_fflags, error); break; case AUE_OPEN_EXTENDED_RWTC: /* * The open_extended syscall always writes a * AUE_OPEN_EXTENDEDRWTC event; change it to the proper type of * event based on the flags and the error value. */ ar->k_ar.ar_event = audit_flags_and_error_to_openextendedevent( 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; case AUE_FCNTL: /* Convert some fcntl() commands to their own events. */ ar->k_ar.ar_event = audit_fcntl_command_event( ar->k_ar.ar_arg_cmd, ar->k_ar.ar_arg_fflags, error); break; } auid = ar->k_ar.ar_subj_auid; event = ar->k_ar.ar_event; class = au_event_class(event); /* * See if we need to override the audit_suspend and audit_enabled * flags. * * XXXss - This check needs to be generalized so new filters can * easily be added. */ audit_override = (AUE_SESSION_START == event || AUE_SESSION_UPDATE == event || AUE_SESSION_END == event || AUE_SESSION_CLOSE == 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 | AR_PRESELECT_FILTER)) == 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_override && (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 int code, proc_t proc, struct uthread *uthread) { struct au_mask *aumask; au_class_t class; au_event_t event; au_id_t auid; kauth_cred_t cred; /* * 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. * * In Mac OS X, the audit events are stored in a table seperate from * the syscall table(s). This table is generated by makesyscalls.sh * from syscalls.master and stored in audit_kevents.c. */ if (code > NUM_SYSENT) return; event = sys_au_event[code]; if (event == AUE_NULL) return; KASSERT(uthread->uu_ar == NULL, ("audit_syscall_enter: uthread->uu_ar != NULL")); /* * Check which audit mask to use; either the kernel non-attributable * event mask or the process audit mask. */ cred = kauth_cred_proc_ref(proc); auid = cred->cr_audit.as_aia_p->ai_auid; if (auid == AU_DEFAUDITID) aumask = &audit_nae_mask; else aumask = &cred->cr_audit.as_mask; /* * Allocate an audit record, if preselection allows it, and store in * the thread for later use. */ class = au_event_class(event); #if CONFIG_MACF /* * Note: audit_mac_syscall_enter() may call audit_new() and allocate * memory for the audit record (uu_ar). */ if (audit_mac_syscall_enter(code, proc, uthread, cred, event) == 0) goto out; #endif 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 && suser(cred, &proc->p_acflag) != 0) { cv_wait(&audit_fail_cv, &audit_mtx); panic("audit_failing_stop: thread continued"); } if (uthread->uu_ar == NULL) uthread->uu_ar = audit_new(event, proc, uthread); } else if (audit_pipe_preselect(auid, event, class, AU_PRS_BOTH, 0)) { if (uthread->uu_ar == NULL) uthread->uu_ar = audit_new(event, proc, uthread); } out: kauth_cred_unref(&cred); } /* * 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. * * Note: The audit_syscall_exit() parameter list was modified to support * mac_audit_check_postselect(), which requires the syscall number. */ #if CONFIG_MACF void audit_syscall_exit(unsigned int code, int error, __unused proc_t proc, struct uthread *uthread) #else void audit_syscall_exit(int error, __unsed proc_t proc, struct uthread *uthread) #endif { 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 = uthread->uu_rval[0]; #if CONFIG_MACF if (audit_mac_syscall_exit(code, uthread, error, retval) != 0) goto out; #endif audit_commit(uthread->uu_ar, error, retval); out: uthread->uu_ar = NULL; } /* * Calls to set up and tear down audit structures used during Mach system * calls. */ void audit_mach_syscall_enter(unsigned short event) { struct uthread *uthread; proc_t proc; struct au_mask *aumask; kauth_cred_t cred; au_class_t class; au_id_t auid; if (event == AUE_NULL) return; uthread = curthread(); if (uthread == NULL) return; proc = current_proc(); if (proc == NULL) return; KASSERT(uthread->uu_ar == NULL, ("audit_mach_syscall_enter: uthread->uu_ar != NULL")); cred = kauth_cred_proc_ref(proc); auid = cred->cr_audit.as_aia_p->ai_auid; /* * Check which audit mask to use; either the kernel non-attributable * event mask or the process audit mask. */ if (auid == AU_DEFAUDITID) aumask = &audit_nae_mask; else aumask = &cred->cr_audit.as_mask; /* * Allocate an audit record, if desired, and store in the BSD thread * for later use. */ class = au_event_class(event); if (au_preselect(event, class, aumask, AU_PRS_BOTH)) uthread->uu_ar = audit_new(event, proc, uthread); else if (audit_pipe_preselect(auid, event, class, AU_PRS_BOTH, 0)) uthread->uu_ar = audit_new(event, proc, uthread); else uthread->uu_ar = NULL; kauth_cred_unref(&cred); } void audit_mach_syscall_exit(int retval, struct uthread *uthread) { /* * The error code from Mach system calls is the same as the * return value */ /* XXX Is the above statement always true? */ audit_commit(uthread->uu_ar, retval, retval); uthread->uu_ar = NULL; } /* * kau_will_audit can be used by a security policy to determine * if an audit record will be stored, reducing wasted memory allocation * and string handling. */ int kau_will_audit(void) { return (audit_enabled && currecord() != NULL); } void audit_proc_coredump(proc_t proc, char *path, int errcode) { struct kaudit_record *ar; struct au_mask *aumask; au_class_t class; int ret, sorf; char **pathp; au_id_t auid; kauth_cred_t my_cred; struct uthread *uthread; ret = 0; /* * Make sure we are using the correct preselection mask. */ my_cred = kauth_cred_proc_ref(proc); auid = my_cred->cr_audit.as_aia_p->ai_auid; if (auid == AU_DEFAUDITID) aumask = &audit_nae_mask; else aumask = &my_cred->cr_audit.as_mask; kauth_cred_unref(&my_cred); /* * 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. */ uthread = curthread(); ar = audit_new(AUE_CORE, proc, uthread); if (path != NULL) { pathp = &ar->k_ar.ar_arg_upath1; *pathp = malloc(MAXPATHLEN, M_AUDITPATH, M_WAITOK); if (audit_canon_path(vfs_context_cwd(vfs_context_current()), path, *pathp)) free(*pathp, M_AUDITPATH); else ARG_SET_VALID(ar, ARG_UPATH1); } ar->k_ar.ar_arg_signum = proc->p_sigacts->ps_sig; ARG_SET_VALID(ar, ARG_SIGNUM); if (errcode != 0) ret = 1; audit_commit(ar, errcode, ret); } #endif /* CONFIG_AUDIT */