From 3e0bd37ce0e4a574df6d87a901e13bcb46e10301 Mon Sep 17 00:00:00 2001 From: Peter Oskolkov Date: Wed, 13 Feb 2019 11:53:35 -0800 Subject: bpf: add plumbing for BPF_LWT_ENCAP_IP in bpf_lwt_push_encap This patch adds all needed plumbing in preparation to allowing bpf programs to do IP encapping via bpf_lwt_push_encap. Actual implementation is added in the next patch in the patchset. Of note: - bpf_lwt_push_encap can now be called from BPF_PROG_TYPE_LWT_XMIT prog types in addition to BPF_PROG_TYPE_LWT_IN; - if the skb being encapped has GSO set, encapsulation is limited to IPIP/IP+GRE/IP+GUE (both IPv4 and IPv6); - as route lookups are different for ingress vs egress, the single external bpf_lwt_push_encap BPF helper is routed internally to either bpf_lwt_in_push_encap or bpf_lwt_xmit_push_encap BPF_CALLs, depending on prog type. v8 changes: fixed a typo. Signed-off-by: Peter Oskolkov Signed-off-by: Alexei Starovoitov --- include/uapi/linux/bpf.h | 26 ++++++++++++++++++++++++-- net/core/filter.c | 48 +++++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 67 insertions(+), 7 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 25c8c0e62ecf..bcdd2474eee7 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2016,6 +2016,19 @@ union bpf_attr { * Only works if *skb* contains an IPv6 packet. Insert a * Segment Routing Header (**struct ipv6_sr_hdr**) inside * the IPv6 header. + * **BPF_LWT_ENCAP_IP** + * IP encapsulation (GRE/GUE/IPIP/etc). The outer header + * must be IPv4 or IPv6, followed by zero or more + * additional headers, up to LWT_BPF_MAX_HEADROOM total + * bytes in all prepended headers. Please note that + * if skb_is_gso(skb) is true, no more than two headers + * can be prepended, and the inner header, if present, + * should be either GRE or UDP/GUE. + * + * BPF_LWT_ENCAP_SEG6*** types can be called by bpf programs of + * type BPF_PROG_TYPE_LWT_IN; BPF_LWT_ENCAP_IP type can be called + * by bpf programs of types BPF_PROG_TYPE_LWT_IN and + * BPF_PROG_TYPE_LWT_XMIT. * * A call to this helper is susceptible to change the underlaying * packet buffer. Therefore, at load time, all checks on pointers @@ -2517,7 +2530,8 @@ enum bpf_hdr_start_off { /* Encapsulation type for BPF_FUNC_lwt_push_encap helper. */ enum bpf_lwt_encap_mode { BPF_LWT_ENCAP_SEG6, - BPF_LWT_ENCAP_SEG6_INLINE + BPF_LWT_ENCAP_SEG6_INLINE, + BPF_LWT_ENCAP_IP, }; #define __bpf_md_ptr(type, name) \ @@ -2606,7 +2620,15 @@ enum bpf_ret_code { BPF_DROP = 2, /* 3-6 reserved */ BPF_REDIRECT = 7, - /* >127 are reserved for prog type specific return codes */ + /* >127 are reserved for prog type specific return codes. + * + * BPF_LWT_REROUTE: used by BPF_PROG_TYPE_LWT_IN and + * BPF_PROG_TYPE_LWT_XMIT to indicate that skb had been + * changed and should be routed based on its new L3 header. + * (This is an L3 redirect, as opposed to L2 redirect + * represented by BPF_REDIRECT above). + */ + BPF_LWT_REROUTE = 128, }; struct bpf_sock { diff --git a/net/core/filter.c b/net/core/filter.c index 353735575204..12c88c21b6b8 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -4815,7 +4815,15 @@ static int bpf_push_seg6_encap(struct sk_buff *skb, u32 type, void *hdr, u32 len } #endif /* CONFIG_IPV6_SEG6_BPF */ -BPF_CALL_4(bpf_lwt_push_encap, struct sk_buff *, skb, u32, type, void *, hdr, +#if IS_ENABLED(CONFIG_LWTUNNEL_BPF) +static int bpf_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, + bool ingress) +{ + return -EINVAL; /* Implemented in the next patch. */ +} +#endif + +BPF_CALL_4(bpf_lwt_in_push_encap, struct sk_buff *, skb, u32, type, void *, hdr, u32, len) { switch (type) { @@ -4823,14 +4831,41 @@ BPF_CALL_4(bpf_lwt_push_encap, struct sk_buff *, skb, u32, type, void *, hdr, case BPF_LWT_ENCAP_SEG6: case BPF_LWT_ENCAP_SEG6_INLINE: return bpf_push_seg6_encap(skb, type, hdr, len); +#endif +#if IS_ENABLED(CONFIG_LWTUNNEL_BPF) + case BPF_LWT_ENCAP_IP: + return bpf_push_ip_encap(skb, hdr, len, true /* ingress */); +#endif + default: + return -EINVAL; + } +} + +BPF_CALL_4(bpf_lwt_xmit_push_encap, struct sk_buff *, skb, u32, type, + void *, hdr, u32, len) +{ + switch (type) { +#if IS_ENABLED(CONFIG_LWTUNNEL_BPF) + case BPF_LWT_ENCAP_IP: + return bpf_push_ip_encap(skb, hdr, len, false /* egress */); #endif default: return -EINVAL; } } -static const struct bpf_func_proto bpf_lwt_push_encap_proto = { - .func = bpf_lwt_push_encap, +static const struct bpf_func_proto bpf_lwt_in_push_encap_proto = { + .func = bpf_lwt_in_push_encap, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, + .arg3_type = ARG_PTR_TO_MEM, + .arg4_type = ARG_CONST_SIZE +}; + +static const struct bpf_func_proto bpf_lwt_xmit_push_encap_proto = { + .func = bpf_lwt_xmit_push_encap, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, @@ -5417,7 +5452,8 @@ bool bpf_helper_changes_pkt_data(void *func) func == bpf_lwt_seg6_adjust_srh || func == bpf_lwt_seg6_action || #endif - func == bpf_lwt_push_encap) + func == bpf_lwt_in_push_encap || + func == bpf_lwt_xmit_push_encap) return true; return false; @@ -5815,7 +5851,7 @@ lwt_in_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { switch (func_id) { case BPF_FUNC_lwt_push_encap: - return &bpf_lwt_push_encap_proto; + return &bpf_lwt_in_push_encap_proto; default: return lwt_out_func_proto(func_id, prog); } @@ -5851,6 +5887,8 @@ lwt_xmit_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_l4_csum_replace_proto; case BPF_FUNC_set_hash_invalid: return &bpf_set_hash_invalid_proto; + case BPF_FUNC_lwt_push_encap: + return &bpf_lwt_xmit_push_encap_proto; default: return lwt_out_func_proto(func_id, prog); } -- cgit v1.2.3-59-g8ed1b