diff options
| author | Menglong Dong <imagedong@tencent.com> | 2022-01-06 14:20:20 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-01-07 02:08:35 +0100 |
| commit | 91a760b26926265a60c77ddf016529bcf3e17a04 (patch) | |
| tree | ae83cb44feeae886d3bebb102371980540bf376b /include/net | |
| parent | bpf/selftests: Test bpf_d_path on rdonly_mem. (diff) | |
| download | linux-91a760b26926265a60c77ddf016529bcf3e17a04.tar.xz linux-91a760b26926265a60c77ddf016529bcf3e17a04.zip | |
net: bpf: Handle return value of BPF_CGROUP_RUN_PROG_INET{4,6}_POST_BIND()
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:
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.
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220106132022.3470772-2-imagedong@tencent.com
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/sock.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index 7b4b4237e6e0..ff9b508d9c5f 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1209,6 +1209,7 @@ struct proto { void (*unhash)(struct sock *sk); void (*rehash)(struct sock *sk); int (*get_port)(struct sock *sk, unsigned short snum); + void (*put_port)(struct sock *sk); #ifdef CONFIG_BPF_SYSCALL int (*psock_update_sk_prot)(struct sock *sk, struct sk_psock *psock, |