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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 /include/linux
parent622adafb2a12cac6042d4d0d7eb735b7621bf28c (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 'include/linux')
-rw-r--r--include/linux/bpf-cgroup.h16
1 files changed, 13 insertions, 3 deletions
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index c6ab295e6dcb..30d15e64b993 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -98,16 +98,24 @@ int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
__ret; \
})
-#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) \
+#define BPF_CGROUP_RUN_SK_PROG(sk, type) \
({ \
int __ret = 0; \
if (cgroup_bpf_enabled) { \
- __ret = __cgroup_bpf_run_filter_sk(sk, \
- BPF_CGROUP_INET_SOCK_CREATE); \
+ __ret = __cgroup_bpf_run_filter_sk(sk, type); \
} \
__ret; \
})
+#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) \
+ BPF_CGROUP_RUN_SK_PROG(sk, BPF_CGROUP_INET_SOCK_CREATE)
+
+#define BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk) \
+ BPF_CGROUP_RUN_SK_PROG(sk, BPF_CGROUP_INET4_POST_BIND)
+
+#define BPF_CGROUP_RUN_PROG_INET6_POST_BIND(sk) \
+ BPF_CGROUP_RUN_SK_PROG(sk, BPF_CGROUP_INET6_POST_BIND)
+
#define BPF_CGROUP_RUN_SA_PROG(sk, uaddr, type) \
({ \
int __ret = 0; \
@@ -183,6 +191,8 @@ static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; }
#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET4_BIND(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET6_BIND(sk, uaddr) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_INET6_POST_BIND(sk) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET4_CONNECT(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET4_CONNECT_LOCK(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr) ({ 0; })