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
