From 12bed760a78da6e12ac8252fec64d019a9eac523 Mon Sep 17 00:00:00 2001 From: Eyal Birger Date: Tue, 24 Apr 2018 17:50:29 +0300 Subject: bpf: add helper for getting xfrm states This commit introduces a helper which allows fetching xfrm state parameters by eBPF programs attached to TC. Prototype: bpf_skb_get_xfrm_state(skb, index, xfrm_state, size, flags) skb: pointer to skb index: the index in the skb xfrm_state secpath array xfrm_state: pointer to 'struct bpf_xfrm_state' size: size of 'struct bpf_xfrm_state' flags: reserved for future extensions The helper returns 0 on success. Non zero if no xfrm state at the index is found - or non exists at all. struct bpf_xfrm_state currently includes the SPI, peer IPv4/IPv6 address and the reqid; it can be further extended by adding elements to its end - indicating the populated fields by the 'size' argument - keeping backwards compatibility. Typical usage: struct bpf_xfrm_state x = {}; bpf_skb_get_xfrm_state(skb, 0, &x, sizeof(x), 0); ... Signed-off-by: Eyal Birger Signed-off-by: Daniel Borkmann --- net/core/filter.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) (limited to 'net/core') diff --git a/net/core/filter.c b/net/core/filter.c index e25bc4a3aa1a..8e45c6c7ab08 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -57,6 +57,7 @@ #include #include #include +#include #include /** @@ -3743,6 +3744,49 @@ static const struct bpf_func_proto bpf_bind_proto = { .arg3_type = ARG_CONST_SIZE, }; +#ifdef CONFIG_XFRM +BPF_CALL_5(bpf_skb_get_xfrm_state, struct sk_buff *, skb, u32, index, + struct bpf_xfrm_state *, to, u32, size, u64, flags) +{ + const struct sec_path *sp = skb_sec_path(skb); + const struct xfrm_state *x; + + if (!sp || unlikely(index >= sp->len || flags)) + goto err_clear; + + x = sp->xvec[index]; + + if (unlikely(size != sizeof(struct bpf_xfrm_state))) + goto err_clear; + + to->reqid = x->props.reqid; + to->spi = x->id.spi; + to->family = x->props.family; + if (to->family == AF_INET6) { + memcpy(to->remote_ipv6, x->props.saddr.a6, + sizeof(to->remote_ipv6)); + } else { + to->remote_ipv4 = x->props.saddr.a4; + } + + return 0; +err_clear: + memset(to, 0, size); + return -EINVAL; +} + +static const struct bpf_func_proto bpf_skb_get_xfrm_state_proto = { + .func = bpf_skb_get_xfrm_state, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, + .arg3_type = ARG_PTR_TO_UNINIT_MEM, + .arg4_type = ARG_CONST_SIZE, + .arg5_type = ARG_ANYTHING, +}; +#endif + static const struct bpf_func_proto * bpf_base_func_proto(enum bpf_func_id func_id) { @@ -3884,6 +3928,10 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_get_socket_cookie_proto; case BPF_FUNC_get_socket_uid: return &bpf_get_socket_uid_proto; +#ifdef CONFIG_XFRM + case BPF_FUNC_skb_get_xfrm_state: + return &bpf_skb_get_xfrm_state_proto; +#endif default: return bpf_base_func_proto(func_id); } -- cgit v1.2.3