diff options
| author | Andrey Ignatov <rdna@fb.com> | 2018-03-30 15:08:07 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-03-31 02:16:26 +0200 |
| commit | aac3fc320d9404f2665a8b1249dc3170d5fa3caf (patch) | |
| tree | 1893d29bcde432c8d807a645a4dbbd2f9ca9fa9a /net/ipv6 | |
| parent | 622adafb2a12cac6042d4d0d7eb735b7621bf28c (diff) | |
bpf: Post-hooks for sys_bind
"Post-hooks" are hooks that are called right before returning from
sys_bind. At this time IP and port are already allocated and no further
changes to `struct sock` can happen before returning from sys_bind but
BPF program has a chance to inspect the socket and change sys_bind
result.
Specifically it can e.g. inspect what port was allocated and if it
doesn't satisfy some policy, BPF program can force sys_bind to fail and
return EPERM to user.
Another example of usage is recording the IP:port pair to some map to
use it in later calls to sys_connect. E.g. if some TCP server inside
cgroup was bound to some IP:port_n, it can be recorded to a map. And
later when some TCP client inside same cgroup is trying to connect to
127.0.0.1:port_n, BPF hook for sys_connect can override the destination
and connect application to IP:port_n instead of 127.0.0.1:port_n. That
helps forcing all applications inside a cgroup to use desired IP and not
break those applications if they e.g. use localhost to communicate
between each other.
== Implementation details ==
Post-hooks are implemented as two new attach types
`BPF_CGROUP_INET4_POST_BIND` and `BPF_CGROUP_INET6_POST_BIND` for
existing prog type `BPF_PROG_TYPE_CGROUP_SOCK`.
Separate attach types for IPv4 and IPv6 are introduced to avoid access
to IPv6 field in `struct sock` from `inet_bind()` and to IPv4 field from
`inet6_bind()` since those fields might not make sense in such cases.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/af_inet6.c | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index 566cec0e0a44..41f50472679d 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -412,13 +412,20 @@ int __inet6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len, sk->sk_ipv6only = 1; /* Make sure we are allowed to bind here. */ - if ((snum || !(inet->bind_address_no_port || - force_bind_address_no_port)) && - sk->sk_prot->get_port(sk, snum)) { - sk->sk_ipv6only = saved_ipv6only; - inet_reset_saddr(sk); - err = -EADDRINUSE; - goto out; + if (snum || !(inet->bind_address_no_port || + force_bind_address_no_port)) { + if (sk->sk_prot->get_port(sk, snum)) { + sk->sk_ipv6only = saved_ipv6only; + inet_reset_saddr(sk); + err = -EADDRINUSE; + goto out; + } + err = BPF_CGROUP_RUN_PROG_INET6_POST_BIND(sk); + if (err) { + sk->sk_ipv6only = saved_ipv6only; + inet_reset_saddr(sk); + goto out; + } } if (addr_type != IPV6_ADDR_ANY) |