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pf: Do not hold PF_RULES_RLOCK while processing Ethernet rules

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Avoid the overhead of acquiring a (read) RULES lock when processing the
Ethernet rules.
We can get away with that because when rules are modified they're staged
in V_pf_keth_inactive. We take care to ensure the swap to V_pf_keth is
atomic, so that pf_test_eth_rule() always sees either the old rules, or
the new ruleset.

We need to take care not to delete the old ruleset until we're sure no
pf_test_eth_rule() is still running with those. We accomplish that by
using NET_EPOCH_CALL() to actually free the old rules.

Sponsored by:	Rubicon Communications, LLC ("Netgate")
Differential Revision:	https://reviews.freebsd.org/D31739
This commit is contained in:
Kristof Provost 2021-02-10 13:28:14 +01:00
parent 2b29ceb86f
commit 20c4899a8e
4 changed files with 43 additions and 17 deletions
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3
sys/net/pfvar.h
View File

@ -39,6 +39,7 @@
#include <sys/queue.h>
#include <sys/counter.h>
#include <sys/cpuset.h>
#include <sys/epoch.h>
#include <sys/malloc.h>
#include <sys/nv.h>
#include <sys/refcount.h>
@ -624,6 +625,8 @@ struct pf_keth_settings {
struct pf_keth_rules rules;
uint32_t ticket;
int open;
struct vnet *vnet;
struct epoch_context epoch_ctx;
};
union pf_krule_ptr {

20
sys/netpfil/pf/pf.c
View File

@ -3712,18 +3712,18 @@ pf_test_eth_rule(int dir, struct pfi_kkif *kif, struct mbuf *m)
struct ether_header *e;
struct pf_keth_rule *r, *rm;
struct pf_mtag *mtag;
struct pf_keth_settings *settings;
uint8_t action;
PF_RULES_RLOCK_TRACKER;
NET_EPOCH_ASSERT();
MPASS(kif->pfik_ifp->if_vnet == curvnet);
NET_EPOCH_ASSERT();
e = mtod(m, struct ether_header *);
PF_RULES_RLOCK();
r = TAILQ_FIRST(&V_pf_keth->rules);
settings = ck_pr_load_ptr(&V_pf_keth);
r = TAILQ_FIRST(&settings->rules);
rm = NULL;
while (r != NULL) {
@ -3753,26 +3753,21 @@ pf_test_eth_rule(int dir, struct pfi_kkif *kif, struct mbuf *m)
r = rm;
/* Default to pass. */
if (r == NULL) {
PF_RULES_RUNLOCK();
if (r == NULL)
return (PF_PASS);
}
/* Execute action. */
counter_u64_add(r->packets[dir == PF_OUT], 1);
counter_u64_add(r->bytes[dir == PF_OUT], m_length(m, NULL));
/* Shortcut. Don't tag if we're just going to drop anyway. */
if (r->action == PF_DROP) {
PF_RULES_RUNLOCK();
if (r->action == PF_DROP)
return (PF_DROP);
}
if (r->tag > 0) {
mtag = pf_get_mtag(m);
if (mtag == NULL) {
counter_u64_add(V_pf_status.counters[PFRES_MEMORY], 1);
PF_RULES_RUNLOCK();
return (PF_DROP);
}
mtag->tag = r->tag;
@ -3782,7 +3777,6 @@ pf_test_eth_rule(int dir, struct pfi_kkif *kif, struct mbuf *m)
mtag = pf_get_mtag(m);
if (mtag == NULL) {
counter_u64_add(V_pf_status.counters[PFRES_MEMORY], 1);
PF_RULES_RUNLOCK();
return (PF_DROP);
}
mtag->qid = r->qid;
@ -3790,8 +3784,6 @@ pf_test_eth_rule(int dir, struct pfi_kkif *kif, struct mbuf *m)
action = r->action;
PF_RULES_RUNLOCK();
return (action);
}

36
sys/netpfil/pf/pf_ioctl.c
View File

@ -107,6 +107,7 @@ static void pf_empty_kpool(struct pf_kpalist *);
static int pfioctl(struct cdev *, u_long, caddr_t, int,
struct thread *);
static int pf_begin_eth(uint32_t *);
static void pf_rollback_eth_cb(struct epoch_context *);
static int pf_rollback_eth(uint32_t);
static int pf_commit_eth(uint32_t);
static void pf_free_eth_rule(struct pf_keth_rule *);
@ -701,6 +702,12 @@ pf_begin_eth(uint32_t *ticket)
PF_RULES_WASSERT();
if (V_pf_keth_inactive->open) {
/* We may be waiting for NET_EPOCH_CALL(pf_rollback_eth_cb) to
* finish. */
return (EBUSY);
}
/* Purge old inactive rules. */
TAILQ_FOREACH_SAFE(rule, &V_pf_keth_inactive->rules, entries, tmp) {
TAILQ_REMOVE(&V_pf_keth_inactive->rules, rule, entries);
@ -713,6 +720,24 @@ pf_begin_eth(uint32_t *ticket)
return (0);
}
static void
pf_rollback_eth_cb(struct epoch_context *ctx)
{
struct pf_keth_settings *settings;
settings = __containerof(ctx, struct pf_keth_settings, epoch_ctx);
CURVNET_SET(settings->vnet);
MPASS(settings == V_pf_keth_inactive);
PF_RULES_WLOCK();
pf_rollback_eth(V_pf_keth_inactive->ticket);
PF_RULES_WUNLOCK();
CURVNET_RESTORE();
}
static int
pf_rollback_eth(uint32_t ticket)
{
@ -780,15 +805,20 @@ pf_commit_eth(uint32_t ticket)
ticket != V_pf_keth_inactive->ticket)
return (EBUSY);
PF_RULES_WASSERT();
pf_eth_calc_skip_steps(&V_pf_keth_inactive->rules);
settings = V_pf_keth;
V_pf_keth = V_pf_keth_inactive;
ck_pr_store_ptr(&V_pf_keth, V_pf_keth_inactive);
V_pf_keth_inactive = settings;
V_pf_keth_inactive->ticket = V_pf_keth->ticket;
/* Clean up inactive rules. */
return (pf_rollback_eth(ticket));
/* Clean up inactive rules (i.e. previously active rules), only when
* we're sure they're no longer used. */
NET_EPOCH_CALL(pf_rollback_eth_cb, &V_pf_keth_inactive->epoch_ctx);
return (0);
}
#ifdef ALTQ

1
sys/netpfil/pf/pf_ruleset.c
View File

@ -154,6 +154,7 @@ pf_init_keth(struct pf_keth_settings *settings)
TAILQ_INIT(&settings->rules);
settings->ticket = 0;
settings->open = 0;
settings->vnet = curvnet;
}
struct pf_kruleset *