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Once pf became not covered by a single mutex, many counters in it became

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race prone. Some just gather statistics, but some are later used in
different calculations.

A real problem was the race provoked underflow of the states_cur counter
on a rule. Once it goes below zero, it wraps to UINT32_MAX. Later this
value is used in pf_state_expires() and any state created by this rule
is immediately expired.

Thus, make fields states_cur, states_tot and src_nodes of struct
pf_rule be counter(9)s.

Thanks to Dennis for providing me shell access to problematic box and
his help with reproducing, debugging and investigating the problem.

Thanks to:		Dennis Yusupoff <dyr smartspb.net>
Also reported by:	dumbbell, pgj, Rambler
Sponsored by:		Nginx, Inc.
This commit is contained in:
Gleb Smirnoff 2014-02-14 10:05:21 +00:00
parent 552ee0e1ed
commit 48278b8846
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=261882
5 changed files with 81 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
sbin/pfctl/pfctl.c
View File

@ -791,17 +791,17 @@ pfctl_print_rule_counters(struct pf_rule *rule, int opts)
}
if (opts & PF_OPT_VERBOSE) {
printf(" [ Evaluations: %-8llu Packets: %-8llu "
"Bytes: %-10llu States: %-6u]\n",
"Bytes: %-10llu States: %-6lu]\n",
(unsigned long long)rule->evaluations,
(unsigned long long)(rule->packets[0] +
rule->packets[1]),
(unsigned long long)(rule->bytes[0] +
rule->bytes[1]), rule->states_cur);
rule->bytes[1]), (uint64_t)rule->states_cur);
if (!(opts & PF_OPT_DEBUG))
printf(" [ Inserted: uid %u pid %u "
"State Creations: %-6u]\n",
"State Creations: %-6lu]\n",
(unsigned)rule->cuid, (unsigned)rule->cpid,
rule->states_tot);
(uint64_t)rule->states_tot);
}
}

9
sys/net/pfvar.h
View File

@ -35,6 +35,7 @@
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/counter.h>
#include <sys/refcount.h>
#include <sys/tree.h>
@ -512,13 +513,9 @@ struct pf_rule {
int rtableid;
u_int32_t timeout[PFTM_MAX];
u_int32_t states_cur;
u_int32_t states_tot;
u_int32_t max_states;
u_int32_t src_nodes;
u_int32_t max_src_nodes;
u_int32_t max_src_states;
u_int32_t spare1; /* netgraph */
u_int32_t max_src_conn;
struct {
u_int32_t limit;
@ -532,6 +529,10 @@ struct pf_rule {
uid_t cuid;
pid_t cpid;
counter_u64_t states_cur;
counter_u64_t states_tot;
counter_u64_t src_nodes;
u_int16_t return_icmp;
u_int16_t return_icmp6;
u_int16_t max_mss;

16
sys/netpfil/pf/if_pfsync.c
View File

@ -438,7 +438,8 @@ pfsync_state_import(struct pfsync_state *sp, u_int8_t flags)
else
r = &V_pf_default_rule;
if ((r->max_states && r->states_cur >= r->max_states))
if ((r->max_states &&
counter_u64_fetch(r->states_cur) >= r->max_states))
goto cleanup;
/*
@ -516,18 +517,15 @@ pfsync_state_import(struct pfsync_state *sp, u_int8_t flags)
st->pfsync_time = time_uptime;
st->sync_state = PFSYNC_S_NONE;
/* XXX when we have nat_rule/anchors, use STATE_INC_COUNTERS */
r->states_cur++;
r->states_tot++;
if (!(flags & PFSYNC_SI_IOCTL))
st->state_flags |= PFSTATE_NOSYNC;
if ((error = pf_state_insert(kif, skw, sks, st)) != 0) {
/* XXX when we have nat_rule/anchors, use STATE_DEC_COUNTERS */
r->states_cur--;
if ((error = pf_state_insert(kif, skw, sks, st)) != 0)
goto cleanup_state;
}
/* XXX when we have nat_rule/anchors, use STATE_INC_COUNTERS */
counter_u64_add(r->states_cur, 1);
counter_u64_add(r->states_tot, 1);
if (!(flags & PFSYNC_SI_IOCTL)) {
st->state_flags &= ~PFSTATE_NOSYNC;

55
sys/netpfil/pf/pf.c
View File

@ -335,27 +335,27 @@ enum { PF_ICMP_MULTI_NONE, PF_ICMP_MULTI_SOLICITED, PF_ICMP_MULTI_LINK };
#define BOUND_IFACE(r, k) \
((r)->rule_flag & PFRULE_IFBOUND) ? (k) : V_pfi_all
#define STATE_INC_COUNTERS(s) \
do { \
s->rule.ptr->states_cur++; \
s->rule.ptr->states_tot++; \
if (s->anchor.ptr != NULL) { \
s->anchor.ptr->states_cur++; \
s->anchor.ptr->states_tot++; \
} \
if (s->nat_rule.ptr != NULL) { \
s->nat_rule.ptr->states_cur++; \
s->nat_rule.ptr->states_tot++; \
} \
#define STATE_INC_COUNTERS(s) \
do { \
counter_u64_add(s->rule.ptr->states_cur, 1); \
counter_u64_add(s->rule.ptr->states_tot, 1); \
if (s->anchor.ptr != NULL) { \
counter_u64_add(s->anchor.ptr->states_cur, 1); \
counter_u64_add(s->anchor.ptr->states_tot, 1); \
} \
if (s->nat_rule.ptr != NULL) { \
counter_u64_add(s->nat_rule.ptr->states_cur, 1);\
counter_u64_add(s->nat_rule.ptr->states_tot, 1);\
} \
} while (0)
#define STATE_DEC_COUNTERS(s) \
do { \
if (s->nat_rule.ptr != NULL) \
s->nat_rule.ptr->states_cur--; \
if (s->anchor.ptr != NULL) \
s->anchor.ptr->states_cur--; \
s->rule.ptr->states_cur--; \
#define STATE_DEC_COUNTERS(s) \
do { \
if (s->nat_rule.ptr != NULL) \
counter_u64_add(s->nat_rule.ptr->states_cur, -1);\
if (s->anchor.ptr != NULL) \
counter_u64_add(s->anchor.ptr->states_cur, -1); \
counter_u64_add(s->rule.ptr->states_cur, -1); \
} while (0)
static MALLOC_DEFINE(M_PFHASH, "pf_hash", "pf(4) hash header structures");
@ -647,7 +647,7 @@ pf_insert_src_node(struct pf_src_node **sn, struct pf_rule *rule,
PF_HASHROW_ASSERT(sh);
if (!rule->max_src_nodes ||
rule->src_nodes < rule->max_src_nodes)
counter_u64_fetch(rule->src_nodes) < rule->max_src_nodes)
(*sn) = uma_zalloc(V_pf_sources_z, M_NOWAIT | M_ZERO);
else
V_pf_status.lcounters[LCNT_SRCNODES]++;
@ -667,7 +667,7 @@ pf_insert_src_node(struct pf_src_node **sn, struct pf_rule *rule,
(*sn)->creation = time_uptime;
(*sn)->ruletype = rule->action;
if ((*sn)->rule.ptr != NULL)
(*sn)->rule.ptr->src_nodes++;
counter_u64_add((*sn)->rule.ptr->src_nodes, 1);
PF_HASHROW_UNLOCK(sh);
V_pf_status.scounters[SCNT_SRC_NODE_INSERT]++;
V_pf_status.src_nodes++;
@ -692,7 +692,7 @@ pf_unlink_src_node_locked(struct pf_src_node *src)
#endif
LIST_REMOVE(src, entry);
if (src->rule.ptr)
src->rule.ptr->src_nodes--;
counter_u64_add(src->rule.ptr->src_nodes, -1);
V_pf_status.scounters[SCNT_SRC_NODE_REMOVALS]++;
V_pf_status.src_nodes--;
}
@ -1478,7 +1478,7 @@ pf_state_expires(const struct pf_state *state)
start = state->rule.ptr->timeout[PFTM_ADAPTIVE_START];
if (start) {
end = state->rule.ptr->timeout[PFTM_ADAPTIVE_END];
states = state->rule.ptr->states_cur; /* XXXGL */
states = counter_u64_fetch(state->rule.ptr->states_cur);
} else {
start = V_pf_default_rule.timeout[PFTM_ADAPTIVE_START];
end = V_pf_default_rule.timeout[PFTM_ADAPTIVE_END];
@ -1587,11 +1587,7 @@ pf_unlink_state(struct pf_state *s, u_int flags)
if (pfsync_delete_state_ptr != NULL)
pfsync_delete_state_ptr(s);
--s->rule.ptr->states_cur;
if (s->nat_rule.ptr != NULL)
--s->nat_rule.ptr->states_cur;
if (s->anchor.ptr != NULL)
--s->anchor.ptr->states_cur;
STATE_DEC_COUNTERS(s);
s->timeout = PFTM_UNLINKED;
@ -3606,7 +3602,8 @@ pf_create_state(struct pf_rule *r, struct pf_rule *nr, struct pf_rule *a,
u_short reason;
/* check maximums */
if (r->max_states && (r->states_cur >= r->max_states)) {
if (r->max_states &&
(counter_u64_fetch(r->states_cur) >= r->max_states)) {
V_pf_status.lcounters[LCNT_STATES]++;
REASON_SET(&reason, PFRES_MAXSTATES);
return (PF_DROP);

47
sys/netpfil/pf/pf_ioctl.c
View File

@ -229,6 +229,10 @@ pfattach(void)
V_pf_default_rule.nr = -1;
V_pf_default_rule.rtableid = -1;
V_pf_default_rule.states_cur = counter_u64_alloc(M_WAITOK);
V_pf_default_rule.states_tot = counter_u64_alloc(M_WAITOK);
V_pf_default_rule.src_nodes = counter_u64_alloc(M_WAITOK);
/* initialize default timeouts */
my_timeout[PFTM_TCP_FIRST_PACKET] = PFTM_TCP_FIRST_PACKET_VAL;
my_timeout[PFTM_TCP_OPENING] = PFTM_TCP_OPENING_VAL;
@ -398,6 +402,9 @@ pf_free_rule(struct pf_rule *rule)
pfi_kif_unref(rule->kif);
pf_anchor_remove(rule);
pf_empty_pool(&rule->rpool.list);
counter_u64_free(rule->states_cur);
counter_u64_free(rule->states_tot);
counter_u64_free(rule->src_nodes);
free(rule, M_PFRULE);
}
@ -1149,6 +1156,9 @@ pfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td
bcopy(&pr->rule, rule, sizeof(struct pf_rule));
if (rule->ifname[0])
kif = malloc(sizeof(*kif), PFI_MTYPE, M_WAITOK);
rule->states_cur = counter_u64_alloc(M_WAITOK);
rule->states_tot = counter_u64_alloc(M_WAITOK);
rule->src_nodes = counter_u64_alloc(M_WAITOK);
rule->cuid = td->td_ucred->cr_ruid;
rule->cpid = td->td_proc ? td->td_proc->p_pid : 0;
TAILQ_INIT(&rule->rpool.list);
@ -1265,6 +1275,9 @@ pfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td
#undef ERROUT
DIOCADDRULE_error:
PF_RULES_WUNLOCK();
counter_u64_free(rule->states_cur);
counter_u64_free(rule->states_tot);
counter_u64_free(rule->src_nodes);
free(rule, M_PFRULE);
if (kif)
free(kif, PFI_MTYPE);
@ -1336,6 +1349,16 @@ pfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td
break;
}
bcopy(rule, &pr->rule, sizeof(struct pf_rule));
/*
* XXXGL: this is what happens when internal kernel
* structures are used as ioctl API structures.
*/
pr->rule.states_cur =
(counter_u64_t )counter_u64_fetch(rule->states_cur);
pr->rule.states_tot =
(counter_u64_t )counter_u64_fetch(rule->states_tot);
pr->rule.src_nodes =
(counter_u64_t )counter_u64_fetch(rule->src_nodes);
if (pf_anchor_copyout(ruleset, rule, pr)) {
PF_RULES_WUNLOCK();
error = EBUSY;
@ -1354,7 +1377,7 @@ pfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td
rule->evaluations = 0;
rule->packets[0] = rule->packets[1] = 0;
rule->bytes[0] = rule->bytes[1] = 0;
rule->states_tot = 0;
counter_u64_zero(rule->states_tot);
}
PF_RULES_WUNLOCK();
break;
@ -1394,15 +1417,14 @@ pfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td
#endif /* INET6 */
newrule = malloc(sizeof(*newrule), M_PFRULE, M_WAITOK);
bcopy(&pcr->rule, newrule, sizeof(struct pf_rule));
if (newrule->ifname[0])
kif = malloc(sizeof(*kif), PFI_MTYPE, M_WAITOK);
newrule->states_cur = counter_u64_alloc(M_WAITOK);
newrule->states_tot = counter_u64_alloc(M_WAITOK);
newrule->src_nodes = counter_u64_alloc(M_WAITOK);
newrule->cuid = td->td_ucred->cr_ruid;
newrule->cpid = td->td_proc ? td->td_proc->p_pid : 0;
TAILQ_INIT(&newrule->rpool.list);
/* Initialize refcounting. */
newrule->states_cur = 0;
newrule->entries.tqe_prev = NULL;
if (newrule->ifname[0])
kif = malloc(sizeof(*kif), PFI_MTYPE, M_WAITOK);
}
#define ERROUT(x) { error = (x); goto DIOCCHANGERULE_error; }
@ -1570,8 +1592,12 @@ pfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td
#undef ERROUT
DIOCCHANGERULE_error:
PF_RULES_WUNLOCK();
if (newrule != NULL)
if (newrule != NULL) {
counter_u64_free(newrule->states_cur);
counter_u64_free(newrule->states_tot);
counter_u64_free(newrule->src_nodes);
free(newrule, M_PFRULE);
}
if (kif != NULL)
free(kif, PFI_MTYPE);
break;
@ -3427,6 +3453,11 @@ shutdown_pf(void)
char nn = '\0';
V_pf_status.running = 0;
counter_u64_free(V_pf_default_rule.states_cur);
counter_u64_free(V_pf_default_rule.states_tot);
counter_u64_free(V_pf_default_rule.src_nodes);
do {
if ((error = pf_begin_rules(&t[0], PF_RULESET_SCRUB, &nn))
!= 0) {