On 9/1/20 3:32 AM, Lorenz Bauer wrote:
This addresses Jakub's feedback for the v1 [1]. Outstanding issues are:
* Can we use rcu_dereference instead of rcu_dereference_raw?
* Is it OK to not take the bucket lock?
* Can we teach the verifier that PTR_TO_BTF_ID can be the same as PTR_TO_SOCKET?
For the last question, I see current implementation is
+ .ctx_arg_info = {
+ { offsetof(struct bpf_iter__sockmap, key),
+ PTR_TO_RDONLY_BUF_OR_NULL },
+ { offsetof(struct bpf_iter__sockmap, sk),
+ PTR_TO_SOCKET_OR_NULL },
+ },
The PTR_TO_BTF_ID might be better as it provides more flexibility and
more fields to access. If in the verifier PTR_TO_SOCKET reg type
is desired, you could add a callback somewhere to check:
if the type is PTR_TO_BTF_ID and the btf_id is 'struct socket",
then you can convert reg type to PTR_TO_SOCKET_OR_NULL.
PTR_TO_SOCK_OR_NULL is used here since PTR_TO_BTF_ID might be
a null pointer.
We could add a bit in register state to indicate a PTR_TO_BTF_ID
could be possibly null or not. For example, a conversion from
PTR_TO_BTF_ID_OR_NULL to PTR_TO_BTF_ID will yield non-null btf_id.
A pointer tracing will yield a possible-null btf_id. If we have this,
it is possible to convert a PTR_TO_BTF_ID to PTR_TO_SOCKET.
Changes in v2:
- Remove unnecessary sk_fullsock checks (Jakub)
- Nits for test output (Jakub)
- Increase number of sockets in tests to 64 (Jakub)
- Handle ENOENT in tests (Jakub)
- Actually test SOCKHASH iteration (myself)
- Fix SOCKHASH iterator initialization (myself)
1: https://lore.kernel.org/bpf/20200828094834.23290-1-lmb@xxxxxxxxxxxxxx/
Lorenz Bauer (4):
net: sockmap: Remove unnecessary sk_fullsock checks
net: Allow iterating sockmap and sockhash
selftests: bpf: Add helper to compare socket cookies
selftests: bpf: Test copying a sockmap via bpf_iter
net/core/sock_map.c | 287 +++++++++++++++++-
.../selftests/bpf/prog_tests/sockmap_basic.c | 141 ++++++++-
tools/testing/selftests/bpf/progs/bpf_iter.h | 9 +
.../selftests/bpf/progs/bpf_iter_sockmap.c | 58 ++++
.../selftests/bpf/progs/bpf_iter_sockmap.h | 3 +
5 files changed, 482 insertions(+), 16 deletions(-)
create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_sockmap.c
create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_sockmap.h
