4020272933
improve performance: - Eliminate custom reference count and condition variable to monitor threads entering the framework, as this had both significant overhead and behaved badly in the face of contention. - Replace reference count with two locks: an rwlock and an sx lock, which will be read-acquired by threads entering the framework depending on whether a give policy entry point is permitted to sleep or not. - Replace previous mutex locking of the reference count for exclusive access with write acquiring of both the policy list sx and rw locks, which occurs only when policies are attached or detached. - Do a lockless read of the dynamic policy list head before acquiring any locks in order to reduce overhead when no dynamic policies are loaded; this a race we can afford to lose. - For every policy entry point invocation, decide whether sleeping is permitted, and if not, use a _NOSLEEP() variant of the composition macros, which will use the rwlock instead of the sxlock. In some cases, we decide which to use based on allocation flags passed to the MAC Framework entry point. As with the move to rwlocks/rmlocks in pfil, this may trigger witness warnings, but these should (generally) be false positives as all acquisition of the locks is for read with two very narrow exceptions for policy load/unload, and those code blocks should never acquire other locks. Sponsored by: Google, Inc. Obtained from: TrustedBSD Project Discussed with: csjp (idea, not specific patch)
182 lines
4.9 KiB
C
182 lines
4.9 KiB
C
/*-
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* Copyright (c) 2003-2004 Networks Associates Technology, Inc.
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* Copyright (c) 2006 SPARTA, Inc.
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* Copyright (c) 2009 Robert N. M. Watson
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* All rights reserved.
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*
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* This software was developed for the FreeBSD Project in part by Network
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* Associates Laboratories, the Security Research Division of Network
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* Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
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* as part of the DARPA CHATS research program.
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*
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* This software was enhanced by SPARTA ISSO under SPAWAR contract
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* N66001-04-C-6019 ("SEFOS").
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*
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* This software was developed at the University of Cambridge Computer
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* Laboratory with support from a grant from Google, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_kdtrace.h"
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#include "opt_mac.h"
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mutex.h>
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#include <sys/sbuf.h>
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#include <sys/systm.h>
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#include <sys/vnode.h>
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#include <sys/mount.h>
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#include <sys/file.h>
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#include <sys/namei.h>
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#include <sys/sdt.h>
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#include <sys/sysctl.h>
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#include <sys/shm.h>
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#include <security/mac/mac_framework.h>
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#include <security/mac/mac_internal.h>
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#include <security/mac/mac_policy.h>
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static struct label *
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mac_sysv_shm_label_alloc(void)
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{
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struct label *label;
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label = mac_labelzone_alloc(M_WAITOK);
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MAC_PERFORM(sysvshm_init_label, label);
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return (label);
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}
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void
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mac_sysvshm_init(struct shmid_kernel *shmsegptr)
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{
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if (mac_labeled & MPC_OBJECT_SYSVSHM)
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shmsegptr->label = mac_sysv_shm_label_alloc();
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else
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shmsegptr->label = NULL;
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}
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static void
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mac_sysv_shm_label_free(struct label *label)
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{
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MAC_PERFORM_NOSLEEP(sysvshm_destroy_label, label);
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mac_labelzone_free(label);
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}
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void
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mac_sysvshm_destroy(struct shmid_kernel *shmsegptr)
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{
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if (shmsegptr->label != NULL) {
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mac_sysv_shm_label_free(shmsegptr->label);
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shmsegptr->label = NULL;
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}
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}
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void
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mac_sysvshm_create(struct ucred *cred, struct shmid_kernel *shmsegptr)
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{
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MAC_PERFORM_NOSLEEP(sysvshm_create, cred, shmsegptr,
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shmsegptr->label);
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}
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void
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mac_sysvshm_cleanup(struct shmid_kernel *shmsegptr)
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{
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MAC_PERFORM_NOSLEEP(sysvshm_cleanup, shmsegptr->label);
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}
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MAC_CHECK_PROBE_DEFINE3(sysvshm_check_shmat, "struct ucred *",
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"struct shmid_kernel *", "int");
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int
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mac_sysvshm_check_shmat(struct ucred *cred, struct shmid_kernel *shmsegptr,
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int shmflg)
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{
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int error;
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MAC_CHECK_NOSLEEP(sysvshm_check_shmat, cred, shmsegptr,
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shmsegptr->label, shmflg);
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MAC_CHECK_PROBE3(sysvshm_check_shmat, error, cred, shmsegptr,
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shmflg);
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return (error);
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}
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MAC_CHECK_PROBE_DEFINE3(sysvshm_check_shmctl, "struct ucred *",
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"struct shmid_kernel *", "int");
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int
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mac_sysvshm_check_shmctl(struct ucred *cred, struct shmid_kernel *shmsegptr,
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int cmd)
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{
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int error;
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MAC_CHECK_NOSLEEP(sysvshm_check_shmctl, cred, shmsegptr,
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shmsegptr->label, cmd);
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MAC_CHECK_PROBE3(sysvshm_check_shmctl, error, cred, shmsegptr, cmd);
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return (error);
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}
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MAC_CHECK_PROBE_DEFINE2(sysvshm_check_shmdt, "struct ucred *",
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"struct shmid *");
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int
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mac_sysvshm_check_shmdt(struct ucred *cred, struct shmid_kernel *shmsegptr)
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{
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int error;
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MAC_CHECK_NOSLEEP(sysvshm_check_shmdt, cred, shmsegptr,
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shmsegptr->label);
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MAC_CHECK_PROBE2(sysvshm_check_shmdt, error, cred, shmsegptr);
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return (error);
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}
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MAC_CHECK_PROBE_DEFINE3(sysvshm_check_shmget, "struct ucred *",
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"struct shmid_kernel *", "int");
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int
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mac_sysvshm_check_shmget(struct ucred *cred, struct shmid_kernel *shmsegptr,
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int shmflg)
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{
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int error;
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MAC_CHECK_NOSLEEP(sysvshm_check_shmget, cred, shmsegptr,
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shmsegptr->label, shmflg);
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MAC_CHECK_PROBE3(sysvshm_check_shmget, error, cred, shmsegptr,
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shmflg);
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return (error);
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}
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