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authorVakul Garg <vakul.garg@nxp.com>2018-09-24 13:05:56 +0300
committerDavid S. Miller <davem@davemloft.net>2018-09-24 22:24:24 +0300
commit9932a29ab1be1427a2ccbdf852a0f131f2849685 (patch)
treeb721798d416991241369628a76f48a872d08bb0a /net/tls
parent094fe7392d6e0c8fa516dca451d4e005a2238e28 (diff)
downloadlinux-9932a29ab1be1427a2ccbdf852a0f131f2849685.tar.xz
net/tls: Fixed race condition in async encryption
On processors with multi-engine crypto accelerators, it is possible that multiple records get encrypted in parallel and their encryption completion is notified to different cpus in multicore processor. This leads to the situation where tls_encrypt_done() starts executing in parallel on different cores. In current implementation, encrypted records are queued to tx_ready_list in tls_encrypt_done(). This requires addition to linked list 'tx_ready_list' to be protected. As tls_decrypt_done() could be executing in irq content, it is not possible to protect linked list addition operation using a lock. To fix the problem, we remove linked list addition operation from the irq context. We do tx_ready_list addition/removal operation from application context only and get rid of possible multiple access to the linked list. Before starting encryption on the record, we add it to the tail of tx_ready_list. To prevent tls_tx_records() from transmitting it, we mark the record with a new flag 'tx_ready' in 'struct tls_rec'. When record encryption gets completed, tls_encrypt_done() has to only update the 'tx_ready' flag to true & linked list add operation is not required. The changed logic brings some other side benefits. Since the records are always submitted in tls sequence number order for encryption, the tx_ready_list always remains sorted and addition of new records to it does not have to traverse the linked list. Lastly, we renamed tx_ready_list in 'struct tls_sw_context_tx' to 'tx_list'. This is because now, the some of the records at the tail are not ready to transmit. Fixes: a42055e8d2c3 ("net/tls: Add support for async encryption") Signed-off-by: Vakul Garg <vakul.garg@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tls')
-rw-r--r--net/tls/tls_main.c4
-rw-r--r--net/tls/tls_sw.c81
2 files changed, 32 insertions, 53 deletions
diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 06094de7a3d9..b428069a1b05 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -212,7 +212,7 @@ int tls_push_pending_closed_record(struct sock *sk,
struct tls_sw_context_tx *ctx = tls_sw_ctx_tx(tls_ctx);
if (tls_is_partially_sent_record(tls_ctx) ||
- !list_empty(&ctx->tx_ready_list))
+ !list_empty(&ctx->tx_list))
return tls_tx_records(sk, flags);
else
return tls_ctx->push_pending_record(sk, flags);
@@ -233,7 +233,7 @@ static void tls_write_space(struct sock *sk)
}
/* Schedule the transmission if tx list is ready */
- if (is_tx_ready(ctx, tx_ctx) && !sk->sk_write_pending) {
+ if (is_tx_ready(tx_ctx) && !sk->sk_write_pending) {
/* Schedule the transmission */
if (!test_and_set_bit(BIT_TX_SCHEDULED, &tx_ctx->tx_bitmask))
schedule_delayed_work(&tx_ctx->tx_work.work, 0);
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index bcb24c498b84..d30d65bf0753 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -329,29 +329,6 @@ static void tls_free_both_sg(struct sock *sk)
&rec->sg_plaintext_size);
}
-static bool append_tx_ready_list(struct tls_context *tls_ctx,
- struct tls_sw_context_tx *ctx,
- struct tls_rec *enc_rec)
-{
- u64 new_seq = be64_to_cpup((const __be64 *)&enc_rec->aad_space);
- struct list_head *pos;
-
- /* Need to insert encrypted record in tx_ready_list sorted
- * as per sequence number. Traverse linked list from tail.
- */
- list_for_each_prev(pos, &ctx->tx_ready_list) {
- struct tls_rec *rec = (struct tls_rec *)pos;
- u64 seq = be64_to_cpup((const __be64 *)&rec->aad_space);
-
- if (new_seq > seq)
- break;
- }
-
- list_add((struct list_head *)&enc_rec->list, pos);
-
- return is_tx_ready(tls_ctx, ctx);
-}
-
int tls_tx_records(struct sock *sk, int flags)
{
struct tls_context *tls_ctx = tls_get_ctx(sk);
@@ -360,7 +337,7 @@ int tls_tx_records(struct sock *sk, int flags)
int tx_flags, rc = 0;
if (tls_is_partially_sent_record(tls_ctx)) {
- rec = list_first_entry(&ctx->tx_ready_list,
+ rec = list_first_entry(&ctx->tx_list,
struct tls_rec, list);
if (flags == -1)
@@ -373,18 +350,15 @@ int tls_tx_records(struct sock *sk, int flags)
goto tx_err;
/* Full record has been transmitted.
- * Remove the head of tx_ready_list
+ * Remove the head of tx_list
*/
- tls_ctx->tx_seq_number++;
list_del(&rec->list);
kfree(rec);
}
- /* Tx all ready records which have expected sequence number */
- list_for_each_entry_safe(rec, tmp, &ctx->tx_ready_list, list) {
- u64 seq = be64_to_cpup((const __be64 *)&rec->aad_space);
-
- if (seq == tls_ctx->tx_seq_number) {
+ /* Tx all ready records */
+ list_for_each_entry_safe(rec, tmp, &ctx->tx_list, list) {
+ if (READ_ONCE(rec->tx_ready)) {
if (flags == -1)
tx_flags = rec->tx_flags;
else
@@ -396,7 +370,6 @@ int tls_tx_records(struct sock *sk, int flags)
if (rc)
goto tx_err;
- tls_ctx->tx_seq_number++;
list_del(&rec->list);
kfree(rec);
} else {
@@ -446,9 +419,18 @@ static void tls_encrypt_done(struct crypto_async_request *req, int err)
}
}
- /* Append the record in tx queue */
- if (rec)
- ready = append_tx_ready_list(tls_ctx, ctx, rec);
+ if (rec) {
+ struct tls_rec *first_rec;
+
+ /* Mark the record as ready for transmission */
+ smp_store_mb(rec->tx_ready, true);
+
+ /* If received record is at head of tx_list, schedule tx */
+ first_rec = list_first_entry(&ctx->tx_list,
+ struct tls_rec, list);
+ if (rec == first_rec)
+ ready = true;
+ }
pending = atomic_dec_return(&ctx->encrypt_pending);
@@ -484,6 +466,8 @@ static int tls_do_encryption(struct sock *sk,
aead_request_set_callback(aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG,
tls_encrypt_done, sk);
+ /* Add the record in tx_list */
+ list_add_tail((struct list_head *)&rec->list, &ctx->tx_list);
atomic_inc(&ctx->encrypt_pending);
rc = crypto_aead_encrypt(aead_req);
@@ -493,9 +477,12 @@ static int tls_do_encryption(struct sock *sk,
rec->sg_encrypted_data[0].length += tls_ctx->tx.prepend_size;
}
- /* Case of encryption failure */
- if (rc && rc != -EINPROGRESS)
+ if (!rc) {
+ WRITE_ONCE(rec->tx_ready, true);
+ } else if (rc != -EINPROGRESS) {
+ list_del(&rec->list);
return rc;
+ }
/* Unhook the record from context if encryption is not failure */
ctx->open_rec = NULL;
@@ -544,13 +531,7 @@ static int tls_push_record(struct sock *sk, int flags,
return rc;
}
- /* Put the record in tx_ready_list and start tx if permitted.
- * This happens only when encryption is not asynchronous.
- */
- if (append_tx_ready_list(tls_ctx, ctx, rec))
- return tls_tx_records(sk, flags);
-
- return 0;
+ return tls_tx_records(sk, flags);
}
static int tls_sw_push_pending_record(struct sock *sk, int flags)
@@ -1566,7 +1547,7 @@ void tls_sw_free_resources_tx(struct sock *sk)
/* Tx whatever records we can transmit and abandon the rest */
tls_tx_records(sk, -1);
- /* Free up un-sent records in tx_ready_list. First, free
+ /* Free up un-sent records in tx_list. First, free
* the partially sent record if any at head of tx_list.
*/
if (tls_ctx->partially_sent_record) {
@@ -1583,13 +1564,13 @@ void tls_sw_free_resources_tx(struct sock *sk)
tls_ctx->partially_sent_record = NULL;
- rec = list_first_entry(&ctx->tx_ready_list,
+ rec = list_first_entry(&ctx->tx_list,
struct tls_rec, list);
list_del(&rec->list);
kfree(rec);
}
- list_for_each_entry_safe(rec, tmp, &ctx->tx_ready_list, list) {
+ list_for_each_entry_safe(rec, tmp, &ctx->tx_list, list) {
free_sg(sk, rec->sg_encrypted_data,
&rec->sg_encrypted_num_elem,
&rec->sg_encrypted_size);
@@ -1633,7 +1614,7 @@ void tls_sw_free_resources_rx(struct sock *sk)
kfree(ctx);
}
-/* The work handler to transmitt the encrypted records in tx_ready_list */
+/* The work handler to transmitt the encrypted records in tx_list */
static void tx_work_handler(struct work_struct *work)
{
struct delayed_work *delayed_work = to_delayed_work(work);
@@ -1700,7 +1681,7 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
crypto_info = &ctx->crypto_send.info;
cctx = &ctx->tx;
aead = &sw_ctx_tx->aead_send;
- INIT_LIST_HEAD(&sw_ctx_tx->tx_ready_list);
+ INIT_LIST_HEAD(&sw_ctx_tx->tx_list);
INIT_DELAYED_WORK(&sw_ctx_tx->tx_work.work, tx_work_handler);
sw_ctx_tx->tx_work.sk = sk;
} else {
@@ -1789,8 +1770,6 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
sw_ctx_rx->sk_poll = sk->sk_socket->ops->poll;
strp_check_rcv(&sw_ctx_rx->strp);
- } else {
- ctx->tx_seq_number = be64_to_cpup((const __be64 *)rec_seq);
}
goto out;