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pf: improve SCTP state validation

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Only create new states for INIT chunks, or when we're creating a
secondary state for a multihomed association.

Store and verify verification tag.

MFC after:	3 weeks
Sponsored by:	Orange Business Services
This commit is contained in:
Kristof Provost 2023-09-01 13:33:56 +02:00
parent 1a28d5fea7
commit 51a78dd276
3 changed files with 46 additions and 11 deletions
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8
sys/net/pfvar.h
View file

@ -900,7 +900,10 @@ struct pf_state_scrub {
#define PFSS_DATA_NOTS 0x0080 /* no timestamp on data packets */
u_int8_t pfss_ttl; /* stashed TTL */
u_int8_t pad;
u_int32_t pfss_ts_mod; /* timestamp modulation */
union {
u_int32_t pfss_ts_mod; /* timestamp modulation */
u_int32_t pfss_v_tag; /* SCTP verification tag */
};
};
struct pf_state_host {
@ -1583,6 +1586,7 @@ struct pf_pdesc {
#define PFDESC_SCTP_DATA 0x0040
#define PFDESC_SCTP_ASCONF 0x0080
#define PFDESC_SCTP_OTHER 0x0100
#define PFDESC_SCTP_ADD_IP 0x0200
u_int16_t sctp_flags;
u_int32_t sctp_initiate_tag;
@ -2297,6 +2301,8 @@ int pf_normalize_tcp_init(struct mbuf *, int, struct pf_pdesc *,
int pf_normalize_tcp_stateful(struct mbuf *, int, struct pf_pdesc *,
u_short *, struct tcphdr *, struct pf_kstate *,
struct pf_state_peer *, struct pf_state_peer *, int *);
int pf_normalize_sctp_init(struct mbuf *, int, struct pf_pdesc *,
struct pf_state_peer *, struct pf_state_peer *);
int pf_normalize_sctp(int, struct pfi_kkif *, struct mbuf *, int,
int, void *, struct pf_pdesc *);
u_int32_t

32
sys/netpfil/pf/pf.c
View file

@ -4909,11 +4909,7 @@ pf_create_state(struct pf_krule *r, struct pf_krule *nr, struct pf_krule *a,
if (s->state_flags & PFSTATE_SCRUB_TCP &&
pf_normalize_tcp_init(m, off, pd, th, &s->src, &s->dst)) {
REASON_SET(&reason, PFRES_MEMORY);
pf_src_tree_remove_state(s);
s->timeout = PFTM_UNLINKED;
STATE_DEC_COUNTERS(s);
pf_free_state(s);
return (PF_DROP);
goto drop;
}
if (s->state_flags & PFSTATE_SCRUB_TCP && s->src.scrub &&
pf_normalize_tcp_stateful(m, off, pd, &reason, th, s,
@ -4922,12 +4918,13 @@ pf_create_state(struct pf_krule *r, struct pf_krule *nr, struct pf_krule *a,
DPFPRINTF(PF_DEBUG_URGENT,
("pf_normalize_tcp_stateful failed on first "
"pkt\n"));
pf_src_tree_remove_state(s);
s->timeout = PFTM_UNLINKED;
STATE_DEC_COUNTERS(s);
pf_free_state(s);
return (PF_DROP);
goto drop;
}
} else if (pd->proto == IPPROTO_SCTP) {
if (pf_normalize_sctp_init(m, off, pd, &s->src, &s->dst))
goto drop;
if (! (pd->sctp_flags & (PFDESC_SCTP_INIT | PFDESC_SCTP_ADD_IP)))
goto drop;
}
s->direction = pd->dir;
@ -5024,6 +5021,13 @@ pf_create_state(struct pf_krule *r, struct pf_krule *nr, struct pf_krule *a,
}
return (PF_DROP);
drop:
pf_src_tree_remove_state(s);
s->timeout = PFTM_UNLINKED;
STATE_DEC_COUNTERS(s);
pf_free_state(s);
return (PF_DROP);
}
static int
@ -5891,6 +5895,13 @@ pf_test_state_sctp(struct pf_kstate **state, struct pfi_kkif *kif,
}
}
if (src->scrub != NULL) {
if (src->scrub->pfss_v_tag == 0) {
src->scrub->pfss_v_tag = pd->hdr.sctp.v_tag;
} else if (src->scrub->pfss_v_tag != pd->hdr.sctp.v_tag)
return (PF_DROP);
}
(*state)->expire = time_uptime;
/* translate source/destination address, if necessary */
@ -5931,6 +5942,7 @@ pf_sctp_multihome_delayed(struct pf_pdesc *pd, int off, struct pfi_kkif *kif,
TAILQ_FOREACH_SAFE(j, &pd->sctp_multihome_jobs, next, tmp) {
PF_RULES_RLOCK();
j->pd.sctp_flags |= PFDESC_SCTP_ADD_IP;
action = pf_test_rule(&r, &sm, kif,
j->m, off, &j->pd, &ra, &rs, NULL);
PF_RULES_RUNLOCK();

17
sys/netpfil/pf/pf_norm.c
View file

@ -1565,11 +1565,28 @@ pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
void
pf_normalize_tcp_cleanup(struct pf_kstate *state)
{
/* XXX Note: this also cleans up SCTP. */
uma_zfree(V_pf_state_scrub_z, state->src.scrub);
uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
/* Someday... flush the TCP segment reassembly descriptors. */
}
int
pf_normalize_sctp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
struct pf_state_peer *src, struct pf_state_peer *dst)
{
src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
if (src->scrub == NULL)
return (1);
dst->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
if (dst->scrub == NULL) {
uma_zfree(V_pf_state_scrub_z, src);
return (1);
}
return (0);
}
int
pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,