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When MAC is enabled and a policy module is loaded, don't unconditionally

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lock mac_ifnet_mtx, which protects labels on struct ifnet, unless at least
one policy is actively using labels on ifnets.  This avoids a global mutex
acquire in certain fast paths -- most noticeably ifnet transmit.  This was
previously invisible by default, as no MAC policies were loaded by default,
but recently became visible due to mac_ntpd being enabled by default.

gallatin@ reports a reduction in PPS overhead from 300% to 2.2% with this
change.  We will want to explore further MAC Framework optimisation to
reduce overhead further, but this brings things more back into the world
of the sane.

MFC after:	3 days
This commit is contained in:
Robert Watson 2019-05-03 20:38:43 +00:00
parent e2621d9657
commit 5c95417dad
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=347058
3 changed files with 51 additions and 26 deletions
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12
sys/security/mac/mac_inet.c
View File

@ -1,5 +1,5 @@
/*-
* Copyright (c) 1999-2002, 2007, 2009 Robert N. M. Watson
* Copyright (c) 1999-2002, 2007, 2009, 2019 Robert N. M. Watson
* Copyright (c) 2001 Ilmar S. Habibulin
* Copyright (c) 2001-2004 Networks Associates Technology, Inc.
* Copyright (c) 2006 SPARTA, Inc.
@ -266,16 +266,17 @@ void
mac_netinet_arp_send(struct ifnet *ifp, struct mbuf *m)
{
struct label *mlabel;
int locked;
if (mac_policy_count == 0)
return;
mlabel = mac_mbuf_to_label(m);
MAC_IFNET_LOCK(ifp);
MAC_IFNET_LOCK(ifp, locked);
MAC_POLICY_PERFORM_NOSLEEP(netinet_arp_send, ifp, ifp->if_label, m,
mlabel);
MAC_IFNET_UNLOCK(ifp);
MAC_IFNET_UNLOCK(ifp, locked);
}
void
@ -310,16 +311,17 @@ void
mac_netinet_igmp_send(struct ifnet *ifp, struct mbuf *m)
{
struct label *mlabel;
int locked;
if (mac_policy_count == 0)
return;
mlabel = mac_mbuf_to_label(m);
MAC_IFNET_LOCK(ifp);
MAC_IFNET_LOCK(ifp, locked);
MAC_POLICY_PERFORM_NOSLEEP(netinet_igmp_send, ifp, ifp->if_label, m,
mlabel);
MAC_IFNET_UNLOCK(ifp);
MAC_IFNET_UNLOCK(ifp, locked);
}
void

22
sys/security/mac/mac_internal.h
View File

@ -1,5 +1,5 @@
/*-
* Copyright (c) 1999-2002, 2006, 2009 Robert N. M. Watson
* Copyright (c) 1999-2002, 2006, 2009, 2019 Robert N. M. Watson
* Copyright (c) 2001 Ilmar S. Habibulin
* Copyright (c) 2001-2004 Networks Associates Technology, Inc.
* Copyright (c) 2006 nCircle Network Security, Inc.
@ -216,8 +216,24 @@ void mac_destroy_label(struct label *label);
int mac_check_structmac_consistent(struct mac *mac);
int mac_allocate_slot(void);
#define MAC_IFNET_LOCK(ifp) mtx_lock(&mac_ifnet_mtx)
#define MAC_IFNET_UNLOCK(ifp) mtx_unlock(&mac_ifnet_mtx)
/*
* Lock ifnets to protect labels only if ifnet labels are in use.
*/
#define MAC_IFNET_LOCK(ifp, locked) do { \
if (mac_labeled & MPC_OBJECT_IFNET) { \
mtx_lock(&mac_ifnet_mtx); \
locked = 1; \
} else { \
locked = 0; \
} \
} while (0)
#define MAC_IFNET_UNLOCK(ifp, locked) do { \
if (locked) { \
mtx_unlock(&mac_ifnet_mtx); \
locked = 0; \
} \
} while (0)
/*
* MAC Framework per-object type functions. It's not yet clear how the

43
sys/security/mac/mac_net.c
View File

@ -1,5 +1,5 @@
/*-
* Copyright (c) 1999-2002, 2009 Robert N. M. Watson
* Copyright (c) 1999-2002, 2009, 2019 Robert N. M. Watson
* Copyright (c) 2001 Ilmar S. Habibulin
* Copyright (c) 2001-2004 Networks Associates Technology, Inc.
* Copyright (c) 2006 SPARTA, Inc.
@ -77,6 +77,11 @@ __FBSDID("$FreeBSD$");
* XXXRW: struct ifnet locking is incomplete in the network code, so we use
* our own global mutex for struct ifnet. Non-ideal, but should help in the
* SMP environment.
*
* This lock is acquired only if a loaded policy is using ifnet labeling.
* This should not ever change during a MAC policy check, itself, but could
* change during setup/return from a check, so we have to condition unlock on
* previous lock.
*/
struct mtx mac_ifnet_mtx;
MTX_SYSINIT(mac_ifnet_mtx, &mac_ifnet_mtx, "mac_ifnet", MTX_DEF);
@ -297,13 +302,14 @@ mac_ifnet_internalize_label(struct label *label, char *string)
void
mac_ifnet_create(struct ifnet *ifp)
{
int locked;
if (mac_policy_count == 0)
return;
MAC_IFNET_LOCK(ifp);
MAC_IFNET_LOCK(ifp, locked);
MAC_POLICY_PERFORM_NOSLEEP(ifnet_create, ifp, ifp->if_label);
MAC_IFNET_UNLOCK(ifp);
MAC_IFNET_UNLOCK(ifp, locked);
}
void
@ -334,16 +340,17 @@ void
mac_ifnet_create_mbuf(struct ifnet *ifp, struct mbuf *m)
{
struct label *label;
int locked;
if (mac_policy_count == 0)
return;
label = mac_mbuf_to_label(m);
MAC_IFNET_LOCK(ifp);
MAC_IFNET_LOCK(ifp, locked);
MAC_POLICY_PERFORM_NOSLEEP(ifnet_create_mbuf, ifp, ifp->if_label, m,
label);
MAC_IFNET_UNLOCK(ifp);
MAC_IFNET_UNLOCK(ifp, locked);
}
MAC_CHECK_PROBE_DEFINE2(bpfdesc_check_receive, "struct bpf_d *",
@ -352,7 +359,7 @@ MAC_CHECK_PROBE_DEFINE2(bpfdesc_check_receive, "struct bpf_d *",
int
mac_bpfdesc_check_receive(struct bpf_d *d, struct ifnet *ifp)
{
int error;
int error, locked;
/* Assume reader lock is enough. */
BPFD_LOCK_ASSERT(d);
@ -360,11 +367,11 @@ mac_bpfdesc_check_receive(struct bpf_d *d, struct ifnet *ifp)
if (mac_policy_count == 0)
return (0);
MAC_IFNET_LOCK(ifp);
MAC_IFNET_LOCK(ifp, locked);
MAC_POLICY_CHECK_NOSLEEP(bpfdesc_check_receive, d, d->bd_label, ifp,
ifp->if_label);
MAC_CHECK_PROBE2(bpfdesc_check_receive, error, d, ifp);
MAC_IFNET_UNLOCK(ifp);
MAC_IFNET_UNLOCK(ifp, locked);
return (error);
}
@ -376,7 +383,7 @@ int
mac_ifnet_check_transmit(struct ifnet *ifp, struct mbuf *m)
{
struct label *label;
int error;
int error, locked;
M_ASSERTPKTHDR(m);
@ -385,11 +392,11 @@ mac_ifnet_check_transmit(struct ifnet *ifp, struct mbuf *m)
label = mac_mbuf_to_label(m);
MAC_IFNET_LOCK(ifp);
MAC_IFNET_LOCK(ifp, locked);
MAC_POLICY_CHECK_NOSLEEP(ifnet_check_transmit, ifp, ifp->if_label, m,
label);
MAC_CHECK_PROBE2(ifnet_check_transmit, error, ifp, m);
MAC_IFNET_UNLOCK(ifp);
MAC_IFNET_UNLOCK(ifp, locked);
return (error);
}
@ -401,7 +408,7 @@ mac_ifnet_ioctl_get(struct ucred *cred, struct ifreq *ifr,
char *elements, *buffer;
struct label *intlabel;
struct mac mac;
int error;
int error, locked;
if (!(mac_labeled & MPC_OBJECT_IFNET))
return (EINVAL);
@ -423,9 +430,9 @@ mac_ifnet_ioctl_get(struct ucred *cred, struct ifreq *ifr,
buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK | M_ZERO);
intlabel = mac_ifnet_label_alloc();
MAC_IFNET_LOCK(ifp);
MAC_IFNET_LOCK(ifp, locked);
mac_ifnet_copy_label(ifp->if_label, intlabel);
MAC_IFNET_UNLOCK(ifp);
MAC_IFNET_UNLOCK(ifp, locked);
error = mac_ifnet_externalize_label(intlabel, elements, buffer,
mac.m_buflen);
mac_ifnet_label_free(intlabel);
@ -444,7 +451,7 @@ mac_ifnet_ioctl_set(struct ucred *cred, struct ifreq *ifr, struct ifnet *ifp)
struct label *intlabel;
struct mac mac;
char *buffer;
int error;
int error, locked;
if (!(mac_labeled & MPC_OBJECT_IFNET))
return (EINVAL);
@ -483,18 +490,18 @@ mac_ifnet_ioctl_set(struct ucred *cred, struct ifreq *ifr, struct ifnet *ifp)
return (error);
}
MAC_IFNET_LOCK(ifp);
MAC_IFNET_LOCK(ifp, locked);
MAC_POLICY_CHECK_NOSLEEP(ifnet_check_relabel, cred, ifp,
ifp->if_label, intlabel);
if (error) {
MAC_IFNET_UNLOCK(ifp);
MAC_IFNET_UNLOCK(ifp, locked);
mac_ifnet_label_free(intlabel);
return (error);
}
MAC_POLICY_PERFORM_NOSLEEP(ifnet_relabel, cred, ifp, ifp->if_label,
intlabel);
MAC_IFNET_UNLOCK(ifp);
MAC_IFNET_UNLOCK(ifp, locked);
mac_ifnet_label_free(intlabel);
return (0);