[PATCH bpf-next 0/2] bpf: allocate extra memory for setsockopt hook buffer

[Stanislav Fomichev <sdf@google.com>]

Current setsockopt hook is limited to the size of the buffer that
user had supplied. Since we always allocate memory and copy the value
into kernel space, allocate just a little bit more in case BPF
program needs to override input data with a larger value.

The canonical example is TCP_CONGESTION socket option where
input buffer is a string and if user calls it with a short string,
BPF program has no way of extending it.

The tests are extended with TCP_CONGESTION use case.

Stanislav Fomichev (2):
  bpf: always allocate at least 16 bytes for setsockopt hook
  selftests/bpf: extend sockopt_sk selftest with TCP_CONGESTION use case

 kernel/bpf/cgroup.c                           | 17 ++++++++++---
 .../testing/selftests/bpf/progs/sockopt_sk.c  | 22 ++++++++++++++++
 tools/testing/selftests/bpf/test_sockopt_sk.c | 25 +++++++++++++++++++
 3 files changed, 60 insertions(+), 4 deletions(-)

-- 
2.22.0.709.g102302147b-goog