| Message ID | 20220106132022.3470772-1-imagedong@tencent.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | net: bpf: handle return value of post_bind{4,6} and add selftests for it | expand |
On Thu, Jan 6, 2022 at 5:20 AM <menglong8.dong@gmail.com> wrote: > > From: Menglong Dong <imagedong@tencent.com> > > The return value of BPF_CGROUP_RUN_PROG_INET{4,6}_POST_BIND() in > __inet_bind() is not handled properly. While the return value > is non-zero, it will set inet_saddr and inet_rcv_saddr to 0 and > exit: > exit: > > err = BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk); > if (err) { > inet->inet_saddr = inet->inet_rcv_saddr = 0; > goto out_release_sock; > } > > Let's take UDP for example and see what will happen. For UDP > socket, it will be added to 'udp_prot.h.udp_table->hash' and > 'udp_prot.h.udp_table->hash2' after the sk->sk_prot->get_port() > called success. If 'inet->inet_rcv_saddr' is specified here, > then 'sk' will be in the 'hslot2' of 'hash2' that it don't belong > to (because inet_saddr is changed to 0), and UDP packet received > will not be passed to this sock. If 'inet->inet_rcv_saddr' is not > specified here, the sock will work fine, as it can receive packet > properly, which is wired, as the 'bind()' is already failed. > > To undo the get_port() operation, introduce the 'put_port' field > for 'struct proto'. For TCP proto, it is inet_put_port(); For UDP > proto, it is udp_lib_unhash(); For icmp proto, it is > ping_unhash(). > > Therefore, after sys_bind() fail caused by > BPF_CGROUP_RUN_PROG_INET4_POST_BIND(), it will be unbinded, which > means that it can try to be binded to another port. > > The second patch use C99 initializers in test_sock.c > > The third patch is the selftests for this modification. > > Changes since v4: > - use C99 initializers in test_sock.c before adding the test case Thanks for the fix. Applied. In the future please make sure to tag your patches with [PATCH bpf-next] so that BPF CI can properly test it right away.
From: Menglong Dong <imagedong@tencent.com> The return value of BPF_CGROUP_RUN_PROG_INET{4,6}_POST_BIND() in __inet_bind() is not handled properly. While the return value is non-zero, it will set inet_saddr and inet_rcv_saddr to 0 and exit: exit: err = BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk); if (err) { inet->inet_saddr = inet->inet_rcv_saddr = 0; goto out_release_sock; } Let's take UDP for example and see what will happen. For UDP socket, it will be added to 'udp_prot.h.udp_table->hash' and 'udp_prot.h.udp_table->hash2' after the sk->sk_prot->get_port() called success. If 'inet->inet_rcv_saddr' is specified here, then 'sk' will be in the 'hslot2' of 'hash2' that it don't belong to (because inet_saddr is changed to 0), and UDP packet received will not be passed to this sock. If 'inet->inet_rcv_saddr' is not specified here, the sock will work fine, as it can receive packet properly, which is wired, as the 'bind()' is already failed. To undo the get_port() operation, introduce the 'put_port' field for 'struct proto'. For TCP proto, it is inet_put_port(); For UDP proto, it is udp_lib_unhash(); For icmp proto, it is ping_unhash(). Therefore, after sys_bind() fail caused by BPF_CGROUP_RUN_PROG_INET4_POST_BIND(), it will be unbinded, which means that it can try to be binded to another port. The second patch use C99 initializers in test_sock.c The third patch is the selftests for this modification. Changes since v4: - use C99 initializers in test_sock.c before adding the test case Changes since v3: - add the third patch which use C99 initializers in test_sock.c Changes since v2: - NULL check for sk->sk_prot->put_port Changes since v1: - introduce 'put_port' field for 'struct proto' - add selftests for it Menglong Dong (3): net: bpf: handle return value of BPF_CGROUP_RUN_PROG_INET{4,6}_POST_BIND() bpf: selftests: use C99 initializers in test_sock.c bpf: selftests: add bind retry for post_bind{4, 6} include/net/sock.h | 1 + net/ipv4/af_inet.c | 2 + net/ipv4/ping.c | 1 + net/ipv4/tcp_ipv4.c | 1 + net/ipv4/udp.c | 1 + net/ipv6/af_inet6.c | 2 + net/ipv6/ping.c | 1 + net/ipv6/tcp_ipv6.c | 1 + net/ipv6/udp.c | 1 + tools/testing/selftests/bpf/test_sock.c | 370 ++++++++++++++---------- 10 files changed, 233 insertions(+), 148 deletions(-)