git: 0a76c63dd498 - main - ng_l2tp: improve seq structure locking.
Gleb Smirnoff
glebius at FreeBSD.org
Fri Sep 10 18:28:00 UTC 2021
The branch main has been updated by glebius:
URL: https://cgit.FreeBSD.org/src/commit/?id=0a76c63dd4987d8f7af37fe93569ce8a020cf43e
commit 0a76c63dd4987d8f7af37fe93569ce8a020cf43e
Author: Gleb Smirnoff <glebius at FreeBSD.org>
AuthorDate: 2021-08-06 22:49:51 +0000
Commit: Gleb Smirnoff <glebius at FreeBSD.org>
CommitDate: 2021-09-10 18:27:13 +0000
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 */
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