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udp: Run SK_LOOKUP BPF program on socket lookup

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Following INET/TCP socket lookup changes, modify UDP socket lookup to let
BPF program select a receiving socket before searching for a socket by
destination address and port as usual.

Lookup of connected sockets that match packet 4-tuple is unaffected by this
change. BPF program runs, and potentially overrides the lookup result, only
if a 4-tuple match was not found.

Suggested-by: Marek Majkowski <marek@cloudflare.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200717103536.397595-9-jakub@cloudflare.com
This commit is contained in:
Jakub Sitnicki 2020-07-17 12:35:29 +02:00 committed by Alexei Starovoitov
parent 7629c73a14
commit 72f7e9440e
1 changed files with 49 additions and 8 deletions
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57
net/ipv4/udp.c
View File

@ -456,6 +456,29 @@ static struct sock *udp4_lib_lookup2(struct net *net,
return result;
}
static inline struct sock *udp4_lookup_run_bpf(struct net *net,
struct udp_table *udptable,
struct sk_buff *skb,
__be32 saddr, __be16 sport,
__be32 daddr, u16 hnum)
{
struct sock *sk, *reuse_sk;
bool no_reuseport;
if (udptable != &udp_table)
return NULL; /* only UDP is supported */
no_reuseport = bpf_sk_lookup_run_v4(net, IPPROTO_UDP,
saddr, sport, daddr, hnum, &sk);
if (no_reuseport || IS_ERR_OR_NULL(sk))
return sk;
reuse_sk = lookup_reuseport(net, sk, skb, saddr, sport, daddr, hnum);
if (reuse_sk)
sk = reuse_sk;
return sk;
}
/* UDP is nearly always wildcards out the wazoo, it makes no sense to try
* harder than this. -DaveM
*/
@ -463,27 +486,45 @@ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
__be16 sport, __be32 daddr, __be16 dport, int dif,
int sdif, struct udp_table *udptable, struct sk_buff *skb)
{
struct sock *result;
unsigned short hnum = ntohs(dport);
unsigned int hash2, slot2;
struct udp_hslot *hslot2;
struct sock *result, *sk;
hash2 = ipv4_portaddr_hash(net, daddr, hnum);
slot2 = hash2 & udptable->mask;
hslot2 = &udptable->hash2[slot2];
/* Lookup connected or non-wildcard socket */
result = udp4_lib_lookup2(net, saddr, sport,
daddr, hnum, dif, sdif,
hslot2, skb);
if (!result) {
hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
slot2 = hash2 & udptable->mask;
hslot2 = &udptable->hash2[slot2];
if (!IS_ERR_OR_NULL(result) && result->sk_state == TCP_ESTABLISHED)
goto done;
result = udp4_lib_lookup2(net, saddr, sport,
htonl(INADDR_ANY), hnum, dif, sdif,
hslot2, skb);
/* Lookup redirect from BPF */
if (static_branch_unlikely(&bpf_sk_lookup_enabled)) {
sk = udp4_lookup_run_bpf(net, udptable, skb,
saddr, sport, daddr, hnum);
if (sk) {
result = sk;
goto done;
}
}
/* Got non-wildcard socket or error on first lookup */
if (result)
goto done;
/* Lookup wildcard sockets */
hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
slot2 = hash2 & udptable->mask;
hslot2 = &udptable->hash2[slot2];
result = udp4_lib_lookup2(net, saddr, sport,
htonl(INADDR_ANY), hnum, dif, sdif,
hslot2, skb);
done:
if (IS_ERR(result))
return NULL;
return result;