[PATCH 0/2] Forbid illegitimate binding via listen(2)
Ivanov Mikhail
ivanov.mikhail1 at huawei-partners.com
Mon Apr 8 09:47:45 UTC 2024
listen(2) can be called without explicit bind(2) call. For a TCP socket
it would result in assigning random port(in some range) to this socket
by the kernel. If Landlock sandbox supports LANDLOCK_ACCESS_NET_BIND_TCP,
this may lead to implicit access to a prohibited (by Landlock sandbox)
port. Malicious sandboxed process can accidentally impersonate a
legitimate server process (if listen(2) assigns it a server port number).
Patch adds hook on socket_listen() that prevents such scenario by checking
LANDLOCK_ACCESS_NET_BIND_TCP access for port 0.
Few tests were added to cover this case.
Code coverage(gcov):
* security/landlock:
lines......: 94.5% (745 of 788 lines)
functions..: 97.1% (100 of 103 functions)
Ivanov Mikhail (2):
landlock: Add hook on socket_listen()
selftests/landlock: Create 'listen_zero', 'deny_listen_zero' tests
security/landlock/net.c | 104 +++++++++++++++++---
tools/testing/selftests/landlock/net_test.c | 89 +++++++++++++++++
2 files changed, 177 insertions(+), 16 deletions(-)
--
2.34.1
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