diff options
| author | Alexei Starovoitov <ast@plumgrid.com> | 2015-06-04 10:11:54 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-06-07 02:01:33 -0700 |
| commit | d691f9e8d4405c334aa10d556e73c8bf44cb0e01 (patch) | |
| tree | 295b1d647364407c42990d916358a72381f4d534 /samples/bpf/sockex3_kern.c | |
| parent | 3431205e03977aaf32bce6d4b16fb8244b510056 (diff) | |
| download | linux-rt-d691f9e8d4405c334aa10d556e73c8bf44cb0e01.tar.gz | |
bpf: allow programs to write to certain skb fields
allow programs read/write skb->mark, tc_index fields and
((struct qdisc_skb_cb *)cb)->data.
mark and tc_index are generically useful in TC.
cb[0]-cb[4] are primarily used to pass arguments from one
program to another called via bpf_tail_call() which can
be seen in sockex3_kern.c example.
All fields of 'struct __sk_buff' are readable to socket and tc_cls_act progs.
mark, tc_index are writeable from tc_cls_act only.
cb[0]-cb[4] are writeable by both sockets and tc_cls_act.
Add verifier tests and improve sample code.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'samples/bpf/sockex3_kern.c')
| -rw-r--r-- | samples/bpf/sockex3_kern.c | 35 |
1 files changed, 11 insertions, 24 deletions
diff --git a/samples/bpf/sockex3_kern.c b/samples/bpf/sockex3_kern.c index 2625b987944f..41ae2fd21b13 100644 --- a/samples/bpf/sockex3_kern.c +++ b/samples/bpf/sockex3_kern.c @@ -89,7 +89,6 @@ static inline __u32 ipv6_addr_hash(struct __sk_buff *ctx, __u64 off) struct globals { struct flow_keys flow; - __u32 nhoff; }; struct bpf_map_def SEC("maps") percpu_map = { @@ -139,7 +138,7 @@ static void update_stats(struct __sk_buff *skb, struct globals *g) static __always_inline void parse_ip_proto(struct __sk_buff *skb, struct globals *g, __u32 ip_proto) { - __u32 nhoff = g->nhoff; + __u32 nhoff = skb->cb[0]; int poff; switch (ip_proto) { @@ -165,7 +164,7 @@ static __always_inline void parse_ip_proto(struct __sk_buff *skb, if (gre_flags & GRE_SEQ) nhoff += 4; - g->nhoff = nhoff; + skb->cb[0] = nhoff; parse_eth_proto(skb, gre_proto); break; } @@ -195,7 +194,7 @@ PROG(PARSE_IP)(struct __sk_buff *skb) if (!g) return 0; - nhoff = g->nhoff; + nhoff = skb->cb[0]; if (unlikely(ip_is_fragment(skb, nhoff))) return 0; @@ -210,7 +209,7 @@ PROG(PARSE_IP)(struct __sk_buff *skb) verlen = load_byte(skb, nhoff + 0/*offsetof(struct iphdr, ihl)*/); nhoff += (verlen & 0xF) << 2; - g->nhoff = nhoff; + skb->cb[0] = nhoff; parse_ip_proto(skb, g, ip_proto); return 0; } @@ -223,7 +222,7 @@ PROG(PARSE_IPV6)(struct __sk_buff *skb) if (!g) return 0; - nhoff = g->nhoff; + nhoff = skb->cb[0]; ip_proto = load_byte(skb, nhoff + offsetof(struct ipv6hdr, nexthdr)); @@ -233,25 +232,21 @@ PROG(PARSE_IPV6)(struct __sk_buff *skb) nhoff + offsetof(struct ipv6hdr, daddr)); nhoff += sizeof(struct ipv6hdr); - g->nhoff = nhoff; + skb->cb[0] = nhoff; parse_ip_proto(skb, g, ip_proto); return 0; } PROG(PARSE_VLAN)(struct __sk_buff *skb) { - struct globals *g = this_cpu_globals(); __u32 nhoff, proto; - if (!g) - return 0; - - nhoff = g->nhoff; + nhoff = skb->cb[0]; proto = load_half(skb, nhoff + offsetof(struct vlan_hdr, h_vlan_encapsulated_proto)); nhoff += sizeof(struct vlan_hdr); - g->nhoff = nhoff; + skb->cb[0] = nhoff; parse_eth_proto(skb, proto); @@ -260,17 +255,13 @@ PROG(PARSE_VLAN)(struct __sk_buff *skb) PROG(PARSE_MPLS)(struct __sk_buff *skb) { - struct globals *g = this_cpu_globals(); __u32 nhoff, label; - if (!g) - return 0; - - nhoff = g->nhoff; + nhoff = skb->cb[0]; label = load_word(skb, nhoff); nhoff += sizeof(struct mpls_label); - g->nhoff = nhoff; + skb->cb[0] = nhoff; if (label & MPLS_LS_S_MASK) { __u8 verlen = load_byte(skb, nhoff); @@ -288,14 +279,10 @@ PROG(PARSE_MPLS)(struct __sk_buff *skb) SEC("socket/0") int main_prog(struct __sk_buff *skb) { - struct globals *g = this_cpu_globals(); __u32 nhoff = ETH_HLEN; __u32 proto = load_half(skb, 12); - if (!g) - return 0; - - g->nhoff = nhoff; + skb->cb[0] = nhoff; parse_eth_proto(skb, proto); return 0; } |