From 0a76c63dd4987d8f7af37fe93569ce8a020cf43e Mon Sep 17 00:00:00 2001 From: Gleb Smirnoff Date: Fri, 6 Aug 2021 15:49:51 -0700 Subject: ng_l2tp: improve seq structure locking. Cover few cases of access to seq without lock missed in 702f98951d5. There are no known bugs fixed with this change, however. With INVARIANTS embed ng_l2tp_seq_check() into lock/unlock macros. Slightly reduce number of locks/unlocks per packet keeping the lock between functions. Reviewed by: mjg, markj Differential Revision: https://reviews.freebsd.org/D31476 --- sys/netgraph/ng_l2tp.c | 147 ++++++++++++++++++++----------------------------- 1 file changed, 61 insertions(+), 86 deletions(-) diff --git a/sys/netgraph/ng_l2tp.c b/sys/netgraph/ng_l2tp.c index 9b6f19f9f0ad..c62bde0c54f7 100644 --- a/sys/netgraph/ng_l2tp.c +++ b/sys/netgraph/ng_l2tp.c @@ -188,10 +188,6 @@ static void ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, static hookpriv_p ng_l2tp_find_session(priv_p privp, u_int16_t sid); static ng_fn_eachhook ng_l2tp_reset_session; -#ifdef INVARIANTS -static void ng_l2tp_seq_check(struct l2tp_seq *seq); -#endif - /* Parse type for struct ng_l2tp_seq_config. */ static const struct ng_parse_struct_field ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO; @@ -335,12 +331,22 @@ static struct ng_type ng_l2tp_typestruct = { }; NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct); -/* Sequence number state sanity checking */ +/* Sequence number state locking & sanity checking */ #ifdef INVARIANTS -#define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq) +static void ng_l2tp_seq_check(struct l2tp_seq *seq); +#define SEQ_LOCK(seq) do { \ + mtx_lock(&(seq)->mtx); \ + ng_l2tp_seq_check(seq); \ +} while (0) +#define SEQ_UNLOCK(seq) do { \ + ng_l2tp_seq_check(seq); \ + mtx_unlock(&(seq)->mtx); \ +} while (0) #else -#define L2TP_SEQ_CHECK(x) do { } while (0) +#define SEQ_LOCK(seq) mtx_lock(&(seq)->mtx) +#define SEQ_UNLOCK(seq) mtx_unlock(&(seq)->mtx) #endif +#define SEQ_LOCK_ASSERT(seq) mtx_assert(&(seq)->mtx, MA_OWNED) /* Whether to use m_copypacket() or m_dup() */ #define L2TP_COPY_MBUF m_copypacket @@ -650,11 +656,10 @@ ng_l2tp_shutdown(node_p node) const priv_p priv = NG_NODE_PRIVATE(node); struct l2tp_seq *const seq = &priv->seq; - /* Sanity check */ - L2TP_SEQ_CHECK(seq); - /* Reset sequence number state */ + SEQ_LOCK(seq); ng_l2tp_seq_reset(priv); + SEQ_UNLOCK(seq); /* Free private data if neither timer is running */ ng_uncallout(&seq->rack_timer, node); @@ -757,9 +762,6 @@ ng_l2tp_rcvdata_lower(hook_p h, item_p item) int error; int len, plen; - /* Sanity check */ - L2TP_SEQ_CHECK(&priv->seq); - /* If not configured, reject */ if (!priv->conf.enabled) { NG_FREE_ITEM(item); @@ -899,18 +901,20 @@ ng_l2tp_rcvdata_lower(hook_p h, item_p item) if ((hdr & L2TP_HDR_CTRL) != 0) { struct l2tp_seq *const seq = &priv->seq; + SEQ_LOCK(seq); + /* Handle receive ack sequence number Nr */ ng_l2tp_seq_recv_nr(priv, nr); /* Discard ZLB packets */ if (m->m_pkthdr.len == 0) { + SEQ_UNLOCK(seq); priv->stats.recvZLBs++; NG_FREE_ITEM(item); NG_FREE_M(m); ERROUT(0); } - mtx_lock(&seq->mtx); /* * If not what we expect or we are busy, drop packet and * send an immediate ZLB ack. @@ -920,23 +924,16 @@ ng_l2tp_rcvdata_lower(hook_p h, item_p item) priv->stats.recvDuplicates++; else priv->stats.recvOutOfOrder++; - mtx_unlock(&seq->mtx); ng_l2tp_xmit_ctrl(priv, NULL, seq->ns); NG_FREE_ITEM(item); NG_FREE_M(m); ERROUT(0); } - /* - * Until we deliver this packet we can't receive next one as - * we have no information for sending ack. - */ - seq->inproc = 1; - mtx_unlock(&seq->mtx); /* Prepend session ID to packet. */ M_PREPEND(m, 2, M_NOWAIT); if (m == NULL) { - seq->inproc = 0; + SEQ_UNLOCK(seq); priv->stats.memoryFailures++; NG_FREE_ITEM(item); ERROUT(ENOBUFS); @@ -944,10 +941,17 @@ ng_l2tp_rcvdata_lower(hook_p h, item_p item) mtod(m, u_int8_t *)[0] = sid >> 8; mtod(m, u_int8_t *)[1] = sid & 0xff; + /* + * Until we deliver this packet we can't receive next one as + * we have no information for sending ack. + */ + seq->inproc = 1; + SEQ_UNLOCK(seq); + /* Deliver packet to upper layers */ NG_FWD_NEW_DATA(error, item, priv->ctrl, m); - mtx_lock(&seq->mtx); + SEQ_LOCK(seq); /* Ready to process next packet. */ seq->inproc = 0; @@ -962,7 +966,7 @@ ng_l2tp_rcvdata_lower(hook_p h, item_p item) NULL, 0); } } - mtx_unlock(&seq->mtx); + SEQ_UNLOCK(seq); ERROUT(error); } @@ -997,8 +1001,6 @@ ng_l2tp_rcvdata_lower(hook_p h, item_p item) /* Deliver data */ NG_FWD_NEW_DATA(error, item, hook, m); done: - /* Done */ - L2TP_SEQ_CHECK(&priv->seq); return (error); } @@ -1016,9 +1018,6 @@ ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item) int i; u_int16_t ns; - /* Sanity check */ - L2TP_SEQ_CHECK(&priv->seq); - /* If not configured, reject */ if (!priv->conf.enabled) { NG_FREE_ITEM(item); @@ -1043,12 +1042,12 @@ ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item) ERROUT(EOVERFLOW); } - mtx_lock(&seq->mtx); + SEQ_LOCK(seq); /* Find next empty slot in transmit queue */ for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++); if (i == L2TP_MAX_XWIN) { - mtx_unlock(&seq->mtx); + SEQ_UNLOCK(seq); priv->stats.xmitDrops++; m_freem(m); ERROUT(ENOBUFS); @@ -1057,7 +1056,7 @@ ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item) /* If peer's receive window is already full, nothing else to do */ if (i >= seq->cwnd) { - mtx_unlock(&seq->mtx); + SEQ_UNLOCK(seq); ERROUT(0); } @@ -1068,10 +1067,9 @@ ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item) ns = seq->ns++; - mtx_unlock(&seq->mtx); - /* Copy packet */ if ((m = L2TP_COPY_MBUF(m, M_NOWAIT)) == NULL) { + SEQ_UNLOCK(seq); priv->stats.memoryFailures++; ERROUT(ENOBUFS); } @@ -1079,8 +1077,6 @@ ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item) /* Send packet and increment xmit sequence number */ error = ng_l2tp_xmit_ctrl(priv, m, ns); done: - /* Done */ - L2TP_SEQ_CHECK(&priv->seq); return (error); } @@ -1098,9 +1094,6 @@ ng_l2tp_rcvdata(hook_p hook, item_p item) int error; int i = 2; - /* Sanity check */ - L2TP_SEQ_CHECK(&priv->seq); - /* If not configured, reject */ if (!priv->conf.enabled) { NG_FREE_ITEM(item); @@ -1161,8 +1154,6 @@ ng_l2tp_rcvdata(hook_p hook, item_p item) /* Send packet */ NG_FWD_NEW_DATA(error, item, priv->lower, m); done: - /* Done */ - L2TP_SEQ_CHECK(&priv->seq); return (error); } @@ -1204,7 +1195,6 @@ ng_l2tp_seq_init(priv_p priv) ng_callout_init(&seq->rack_timer); ng_callout_init(&seq->xack_timer); mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF); - L2TP_SEQ_CHECK(seq); } /* @@ -1240,10 +1230,13 @@ ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf) { struct l2tp_seq *const seq = &priv->seq; u_int16_t new_wmax; + int error = 0; + SEQ_LOCK(seq); /* If disabling node, reset state sequence number */ if (!conf->enabled) { ng_l2tp_seq_reset(priv); + SEQ_UNLOCK(seq); return (0); } @@ -1252,13 +1245,14 @@ ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf) if (new_wmax > L2TP_MAX_XWIN) new_wmax = L2TP_MAX_XWIN; if (new_wmax == 0) - return (EINVAL); + ERROUT(EINVAL); if (new_wmax < seq->wmax) - return (EBUSY); + ERROUT(EBUSY); seq->wmax = new_wmax; - /* Done */ - return (0); +done: + SEQ_UNLOCK(seq); + return (error); } /* @@ -1271,8 +1265,7 @@ ng_l2tp_seq_reset(priv_p priv) hook_p hook; int i; - /* Sanity check */ - L2TP_SEQ_CHECK(seq); + SEQ_LOCK_ASSERT(seq); /* Stop timers */ ng_uncallout(&seq->rack_timer, priv->node); @@ -1299,9 +1292,6 @@ ng_l2tp_seq_reset(priv_p priv) seq->acks = 0; seq->rexmits = 0; bzero(seq->xwin, sizeof(seq->xwin)); - - /* Done */ - L2TP_SEQ_CHECK(seq); } /* @@ -1316,15 +1306,12 @@ ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr) int i, j; uint16_t ns; - mtx_lock(&seq->mtx); + SEQ_LOCK_ASSERT(seq); /* Verify peer's ACK is in range */ - if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) { - mtx_unlock(&seq->mtx); + if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) return; /* duplicate ack */ - } if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) { - mtx_unlock(&seq->mtx); priv->stats.recvBadAcks++; /* ack for packet not sent */ return; } @@ -1375,10 +1362,8 @@ ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr) ng_uncallout(&seq->rack_timer, priv->node); /* If transmit queue is empty, we're done for now */ - if (seq->xwin[0] == NULL) { - mtx_unlock(&seq->mtx); + if (seq->xwin[0] == NULL) return; - } /* Start restransmit timer again */ ng_callout(&seq->rack_timer, priv->node, NULL, @@ -1396,8 +1381,6 @@ ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr) seq->ns++; } - mtx_unlock(&seq->mtx); - /* * Send prepared. * If there is a memory error, pretend packet was sent, as it @@ -1407,8 +1390,10 @@ ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr) struct mbuf *m; if ((m = L2TP_COPY_MBUF(xwin[i], M_NOWAIT)) == NULL) priv->stats.memoryFailures++; - else + else { ng_l2tp_xmit_ctrl(priv, m, ns); + SEQ_LOCK(seq); + } ns++; } } @@ -1428,17 +1413,13 @@ ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2) (!callout_active(&seq->xack_timer))) return; - /* Sanity check */ - L2TP_SEQ_CHECK(seq); + SEQ_LOCK(seq); /* Send a ZLB */ ng_l2tp_xmit_ctrl(priv, NULL, seq->ns); /* callout_deactivate() is not needed here as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */ - - /* Sanity check */ - L2TP_SEQ_CHECK(seq); } /* @@ -1453,14 +1434,12 @@ ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2) struct mbuf *m; u_int delay; - /* Sanity check */ - L2TP_SEQ_CHECK(seq); + SEQ_LOCK(seq); - mtx_lock(&seq->mtx); /* Make sure callout is still active before doing anything */ if (callout_pending(&seq->rack_timer) || !callout_active(&seq->rack_timer)) { - mtx_unlock(&seq->mtx); + SEQ_UNLOCK(seq); return; } @@ -1485,41 +1464,39 @@ ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2) /* Retransmit oldest unack'd packet */ m = L2TP_COPY_MBUF(seq->xwin[0], M_NOWAIT); - mtx_unlock(&seq->mtx); - if (m == NULL) + if (m == NULL) { + SEQ_UNLOCK(seq); priv->stats.memoryFailures++; - else + } else ng_l2tp_xmit_ctrl(priv, m, seq->ns++); /* callout_deactivate() is not needed here as ng_callout() is getting called each time */ - - /* Sanity check */ - L2TP_SEQ_CHECK(seq); } /* * Transmit a control stream packet, payload optional. * The transmit sequence number is not incremented. + * Requires seq lock, returns unlocked. */ static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns) { struct l2tp_seq *const seq = &priv->seq; uint8_t *p; - u_int16_t session_id = 0; + uint16_t nr, session_id = 0; int error; - mtx_lock(&seq->mtx); + SEQ_LOCK_ASSERT(seq); /* Stop ack timer: we're sending an ack with this packet. Doing this before to keep state predictable after error. */ if (callout_active(&seq->xack_timer)) ng_uncallout(&seq->xack_timer, priv->node); - seq->xack = seq->nr; + nr = seq->xack = seq->nr; - mtx_unlock(&seq->mtx); + SEQ_UNLOCK(seq); /* If no mbuf passed, send an empty packet (ZLB) */ if (m == NULL) { @@ -1570,8 +1547,8 @@ ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns) p[7] = session_id & 0xff; p[8] = ns >> 8; p[9] = ns & 0xff; - p[10] = seq->nr >> 8; - p[11] = seq->nr & 0xff; + p[10] = nr >> 8; + p[11] = nr & 0xff; /* Update sequence number info and stats */ priv->stats.xmitPackets++; @@ -1594,7 +1571,7 @@ ng_l2tp_seq_check(struct l2tp_seq *seq) #define CHECK(p) KASSERT((p), ("%s: not: %s", __func__, #p)) - mtx_lock(&seq->mtx); + SEQ_LOCK_ASSERT(seq); self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack); peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack); @@ -1617,8 +1594,6 @@ ng_l2tp_seq_check(struct l2tp_seq *seq) for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */ CHECK(seq->xwin[i] == NULL); - mtx_unlock(&seq->mtx); - #undef CHECK } #endif /* INVARIANTS */ -- cgit v1.2.3