[PATCH bpf-next v1 0/2] bpf,ktls: Fix data corruption caused by using bpf_msg_pop_data() in ktls

[Jiayuan Chen <jiayuan.chen@linux.dev>]

Cong reported an issue where running 'test_sockmap' in the current
bpf-next tree results in an error [1].

The specific test case that triggered the error is a combined test
involving ktls and bpf_msg_pop_data().

Root Cause:
When sending plaintext data, we initially calculated the corresponding
ciphertext length. However, if we later reduced the plaintext data length
via socket policy, we failed to recalculate the ciphertext length.

This results in transmitting buffers containing uninitialized data during
ciphertext transmission.

This causes uninitialized bytes to be appended after a complete
"Application Data" packet, leading to errors on the receiving end when
parsing TLS record.

This issue has existed for a long time but was only exposed after the
following test code was merged.
commit 47eae080410b ("selftests/bpf: Add more tests for test_txmsg_push_pop in test_sockmap")

Although we already had tests for pop data before this commit, the
pop data length was insufficient (less than 5 bytes). This meant that the
corrupted TLS records with data length <5 bytes were cached without being
parsed, resulting in no error being triggered.

After this fix, all tests pass.

 1/ 6  sockmap::txmsg test passthrough:OK
 2/ 6  sockmap::txmsg test redirect:OK
 3/ 2  sockmap::txmsg test redirect wait send mem:OK
 4/ 6  sockmap::txmsg test drop:OK
 5/ 6  sockmap::txmsg test ingress redirect:OK
 6/ 7  sockmap::txmsg test skb:OK
 7/12  sockmap::txmsg test apply:OK
 8/12  sockmap::txmsg test cork:OK
 9/ 3  sockmap::txmsg test hanging corks:OK
10/11  sockmap::txmsg test push_data:OK
11/17  sockmap::txmsg test pull-data:OK
12/ 9  sockmap::txmsg test pop-data:OK
13/ 6  sockmap::txmsg test push/pop data:OK
14/ 1  sockmap::txmsg test ingress parser:OK
15/ 1  sockmap::txmsg test ingress parser2:OK
16/ 6 sockhash::txmsg test passthrough:OK
17/ 6 sockhash::txmsg test redirect:OK
18/ 2 sockhash::txmsg test redirect wait send mem:OK
19/ 6 sockhash::txmsg test drop:OK
20/ 6 sockhash::txmsg test ingress redirect:OK
21/ 7 sockhash::txmsg test skb:OK
22/12 sockhash::txmsg test apply:OK
23/12 sockhash::txmsg test cork:OK
24/ 3 sockhash::txmsg test hanging corks:OK
25/11 sockhash::txmsg test push_data:OK
26/17 sockhash::txmsg test pull-data:OK
27/ 9 sockhash::txmsg test pop-data:OK
28/ 6 sockhash::txmsg test push/pop data:OK
29/ 1 sockhash::txmsg test ingress parser:OK
30/ 1 sockhash::txmsg test ingress parser2:OK
31/ 6 sockhash:ktls:txmsg test passthrough:OK
32/ 6 sockhash:ktls:txmsg test redirect:OK
33/ 2 sockhash:ktls:txmsg test redirect wait send mem:OK
34/ 6 sockhash:ktls:txmsg test drop:OK
35/ 6 sockhash:ktls:txmsg test ingress redirect:OK
36/ 7 sockhash:ktls:txmsg test skb:OK
37/12 sockhash:ktls:txmsg test apply:OK
38/12 sockhash:ktls:txmsg test cork:OK
39/ 3 sockhash:ktls:txmsg test hanging corks:OK
40/11 sockhash:ktls:txmsg test push_data:OK
41/17 sockhash:ktls:txmsg test pull-data:OK
42/ 9 sockhash:ktls:txmsg test pop-data:OK
43/ 6 sockhash:ktls:txmsg test push/pop data:OK
44/ 1 sockhash:ktls:txmsg test ingress parser:OK
45/ 0 sockhash:ktls:txmsg test ingress parser2:OK
Pass: 45 Fail: 0

[1]: https://lore.kernel.org/bpf/CAM_iQpU7=4xjbefZoxndKoX9gFFMOe7FcWMq5tHBsymbrnMHxQ@mail.gmail.com/

Jiayuan Chen (2):
  bpf,ktls: Fix data corruption when using bpf_msg_pop_data() in ktls
  selftests/bpf: Add test to cover ktls with bpf_msg_pop_data

 net/tls/tls_sw.c                              | 15 +++
 .../selftests/bpf/prog_tests/sockmap_ktls.c   | 91 +++++++++++++++++++
 .../selftests/bpf/progs/test_sockmap_ktls.c   |  4 +
 3 files changed, 110 insertions(+)

-- 
2.47.1