path: root/net/ipv4/af_inet.c
diff options
authorAndrey Ignatov <rdna@fb.com>2018-03-30 15:08:07 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2018-03-31 02:16:26 +0200
commitaac3fc320d9404f2665a8b1249dc3170d5fa3caf (patch)
tree1893d29bcde432c8d807a645a4dbbd2f9ca9fa9a /net/ipv4/af_inet.c
parentselftests/bpf: Selftest for sys_connect hooks (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, BPF hook for sys_connect can override the destination and connect application to IP:port_n instead of 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/ipv4/af_inet.c')
1 files changed, 12 insertions, 6 deletions
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 488fe26ac8e5..142d4c35b493 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -519,12 +519,18 @@ int __inet_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len,
inet->inet_saddr = 0; /* Use device */
/* 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)) {
- inet->inet_saddr = inet->inet_rcv_saddr = 0;
- err = -EADDRINUSE;
- goto out_release_sock;
+ if (snum || !(inet->bind_address_no_port ||
+ force_bind_address_no_port)) {
+ if (sk->sk_prot->get_port(sk, snum)) {
+ inet->inet_saddr = inet->inet_rcv_saddr = 0;
+ err = -EADDRINUSE;
+ goto out_release_sock;
+ }
+ if (err) {
+ inet->inet_saddr = inet->inet_rcv_saddr = 0;
+ goto out_release_sock;
+ }
if (inet->inet_rcv_saddr)