On Sat, Feb 11, 2023 at 12:19 PM -08, Cong Wang wrote: > From: Cong Wang <cong.wang@xxxxxxxxxxxxx> > > Currently there is no way to know which sockmap a socket has been added > to from outside, especially for that a socket can be added to multiple > sockmap's. We could dump this via socket diag, as shown below. > > Sample output: > > # ./iproute2/misc/ss -tnaie --sockmap > ESTAB 0 344329 127.0.0.1:1234 127.0.0.1:40912 ino:21098 sk:5 cgroup:/user.slice/user-0.slice/session-c1.scope <-> sockmap: 1 > > # bpftool map > 1: sockmap flags 0x0 > key 4B value 4B max_entries 2 memlock 4096B > pids echo-sockmap(549) > 4: array name pid_iter.rodata flags 0x480 > key 4B value 4B max_entries 1 memlock 4096B > btf_id 10 frozen > pids bpftool(624) > > In the future, we could dump other sockmap related stats too, hence I > make it a nested attribute. > > Cc: John Fastabend <john.fastabend@xxxxxxxxx> > Cc: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx> > Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx> > --- Sorry for not replying sooner. This sounds useful. Another use case I can see here is inspecting process' sockets: 1. get a dup FD with pidfd_getfd() 2. query sock_diag by socket cookie 3. find out which maps socket is in. I don't know if it makes sense to tie the naming to sockmap. We also have also map type that can hold socket references - REUSEPORT_SOCKARRAY. We might want to add sock_diag support for REUSEPORT_SOCKARRAY in the future as well. So a map-type-agnostic name for the new inet_diag ext might be more future proof. Like INET_DIAG_BPF_MAP. Also, can you please add a simple selftest? They often serve as the only documentation for the features. Perhaps in tools/testing/selftests/bpf/prog_tests/sockmap_basic.c. Thanks, Jakub
