Merge branch 'net-tls-fix-scatter-gather-list-issues'

Jakub Kicinski says:

====================
net: tls: fix scatter-gather list issues

This series kicked of by a syzbot report fixes three issues around
scatter gather handling in the TLS code. First patch fixes a use-
-after-free situation which may occur if record was freed on error.
This could have already happened in BPF paths, and patch 2 now makes
the same condition occur in non-BPF code.

Patch 2 fixes the problem spotted by syzbot. If encryption failed
we have to clean the end markings from scatter gather list. As
suggested by John the patch frees the record entirely and caller
may retry copying data from user space buffer again.

Third patch fixes a bug in the TLS 1.3 code spotted while working
on patch 2. TLS 1.3 may effectively overflow the SG list which
leads to the BUG() in sg_page() being triggered.

Patch 4 adds a test case which triggers this bug reliably.

Next two patches are small cleanups of dead code and code which
makes dangerous assumptions.

Last but not least two minor improvements to the sockmap tests.

Tested:
 - bpf/test_sockmap
 - net/tls
 - syzbot repro (which used error injection, hence no direct
   selftest is added to preserve it).
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 13 deletions

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index da9f9ce51e7b..2b2d0bae14a9 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -710,8 +710,7 @@ static int tls_push_record(struct sock *sk, int flags,
 	}
 
 	i = msg_pl->sg.start;
-	sg_chain(rec->sg_aead_in, 2, rec->inplace_crypto ?
-		 &msg_en->sg.data[i] : &msg_pl->sg.data[i]);
+	sg_chain(rec->sg_aead_in, 2, &msg_pl->sg.data[i]);
 
 	i = msg_en->sg.end;
 	sk_msg_iter_var_prev(i);
@@ -771,8 +770,14 @@ static int bpf_exec_tx_verdict(struct sk_msg *msg, struct sock *sk,
 
 	policy = !(flags & MSG_SENDPAGE_NOPOLICY);
 	psock = sk_psock_get(sk);
-	if (!psock || !policy)
-		return tls_push_record(sk, flags, record_type);
+	if (!psock || !policy) {
+		err = tls_push_record(sk, flags, record_type);
+		if (err) {
+			*copied -= sk_msg_free(sk, msg);
+			tls_free_open_rec(sk);
+		}
+		return err;
+	}
 more_data:
 	enospc = sk_msg_full(msg);
 	if (psock->eval == __SK_NONE) {
@@ -970,8 +975,6 @@ alloc_encrypted:
 			if (ret)
 				goto fallback_to_reg_send;
 
-			rec->inplace_crypto = 0;
-
 			num_zc++;
 			copied += try_to_copy;
 
@@ -984,7 +987,7 @@ alloc_encrypted:
 					num_async++;
 				else if (ret == -ENOMEM)
 					goto wait_for_memory;
-				else if (ret == -ENOSPC)
+				else if (ctx->open_rec && ret == -ENOSPC)
 					goto rollback_iter;
 				else if (ret != -EAGAIN)
 					goto send_end;
@@ -1053,11 +1056,12 @@ wait_for_memory:
 		ret = sk_stream_wait_memory(sk, &timeo);
 		if (ret) {
 trim_sgl:
-			tls_trim_both_msgs(sk, orig_size);
+			if (ctx->open_rec)
+				tls_trim_both_msgs(sk, orig_size);
 			goto send_end;
 		}
 
-		if (msg_en->sg.size < required_size)
+		if (ctx->open_rec && msg_en->sg.size < required_size)
 			goto alloc_encrypted;
 	}
 
@@ -1169,7 +1173,6 @@ alloc_payload:
 
 		tls_ctx->pending_open_record_frags = true;
 		if (full_record || eor || sk_msg_full(msg_pl)) {
-			rec->inplace_crypto = 0;
 			ret = bpf_exec_tx_verdict(msg_pl, sk, full_record,
 						  record_type, &copied, flags);
 			if (ret) {
@@ -1190,11 +1193,13 @@ wait_for_sndbuf:
 wait_for_memory:
 		ret = sk_stream_wait_memory(sk, &timeo);
 		if (ret) {
-			tls_trim_both_msgs(sk, msg_pl->sg.size);
+			if (ctx->open_rec)
+				tls_trim_both_msgs(sk, msg_pl->sg.size);
 			goto sendpage_end;
 		}
 
-		goto alloc_payload;
+		if (ctx->open_rec)
+			goto alloc_payload;
 	}
 
 	if (num_async) {
@@ -2084,7 +2089,8 @@ void tls_sw_release_resources_tx(struct sock *sk)
 	/* Free up un-sent records in tx_list. First, free
 	 * the partially sent record if any at head of tx_list.
 	 */
-	if (tls_free_partial_record(sk, tls_ctx)) {
+	if (tls_ctx->partially_sent_record) {
+		tls_free_partial_record(sk, tls_ctx);
 		rec = list_first_entry(&ctx->tx_list,
 				       struct tls_rec, list);
 		list_del(&rec->list);