[PATCH 6.1 063/215] tls: fix peeking with sync+async decryption

Greg Kroah-Hartman
2024-03-04T21:45:01Z

From: Sabrina Dubroca <sd@queasysnail.net>

[ Upstream commit 6caaf104423d809b49a67ee6500191d063b40dc6 ]

If we peek from 2 records with a currently empty rx_list, and the
first record is decrypted synchronously but the second record is
decrypted async, the following happens:
1. decrypt record 1 (sync)
2. copy from record 1 to the userspace's msg
3. queue the decrypted record to rx_list for future read(!PEEK)
4. decrypt record 2 (async)
5. queue record 2 to rx_list
6. call process_rx_list to copy data from the 2nd record

We currently pass copied=0 as skip offset to process_rx_list, so we
end up copying once again from the first record. We should skip over
the data we've already copied.

Seen with selftest tls.12_aes_gcm.recv_peek_large_buf_mult_recs

Fixes: 692d7b5d1f91 ("tls: Fix recvmsg() to be able to peek across multiple records")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://lore.kernel.org/r/1b132d2b2b99296bfde54e8a67672d90d6d16e71.1709132643.git.sd@queasysnail.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/tls/tls_sw.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index c6ad435a44218..2bd27b77769cb 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2023,6 +2023,7 @@ int tls_sw_recvmsg(struct sock *sk,
struct strp_msg *rxm;
struct tls_msg *tlm;
ssize_t copied = 0;
+ ssize_t peeked = 0;
bool async = false;
int target, err;
bool is_kvec = iov_iter_is_kvec(&msg->msg_iter);
@@ -2170,8 +2171,10 @@ int tls_sw_recvmsg(struct sock *sk,
if (err < 0)
goto put_on_rx_list_err;

- if (is_peek)
+ if (is_peek) {
+ peeked += chunk;
goto put_on_rx_list;
+ }

if (partially_consumed) {
rxm->offset += chunk;
@@ -2210,8 +2213,8 @@ int tls_sw_recvmsg(struct sock *sk,

/* Drain records from the rx_list & copy if required */
if (is_peek || is_kvec)
- err = process_rx_list(ctx, msg, &control, copied,
- decrypted, is_peek, NULL);
+ err = process_rx_list(ctx, msg, &control, copied + peeked,
+ decrypted - peeked, is_peek, NULL);
else
err = process_rx_list(ctx, msg, &control, 0,
async_copy_bytes, is_peek, NULL);
--
2.43.0