Rename the existing reuseport helpers for IPv4 and IPv6 so that they can be invoked in the follow up commit. Export them so that DCCP which may be built as a module can access them.

No change in functionality.

Signed-off-by: Lorenz Bauer lmb@isovalent.com --- include/net/inet6_hashtables.h | 7 +++++++ include/net/inet_hashtables.h | 5 +++++ net/ipv4/inet_hashtables.c | 15 ++++++++------- net/ipv6/inet6_hashtables.c | 19 ++++++++++--------- 4 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h index 56f1286583d3..032ddab48f8f 100644 --- a/include/net/inet6_hashtables.h +++ b/include/net/inet6_hashtables.h @@ -48,6 +48,13 @@ struct sock *__inet6_lookup_established(struct net *net, const u16 hnum, const int dif, const int sdif);

+struct sock *inet6_lookup_reuseport(struct net *net, struct sock *sk, + struct sk_buff *skb, int doff, + const struct in6_addr *saddr, + __be16 sport, + const struct in6_addr *daddr, + unsigned short hnum); + struct sock *inet6_lookup_listener(struct net *net, struct inet_hashinfo *hashinfo, struct sk_buff *skb, int doff, diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index 99bd823e97f6..8734f3488f5d 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -379,6 +379,11 @@ struct sock *__inet_lookup_established(struct net *net, const __be32 daddr, const u16 hnum, const int dif, const int sdif);

+struct sock *inet_lookup_reuseport(struct net *net, struct sock *sk, + struct sk_buff *skb, int doff, + __be32 saddr, __be16 sport, + __be32 daddr, unsigned short hnum); + static inline struct sock * inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, const __be32 saddr, const __be16 sport, diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index e7391bf310a7..920131e4a65d 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -332,10 +332,10 @@ static inline int compute_score(struct sock *sk, struct net *net, return score; }

-static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk, - struct sk_buff *skb, int doff, - __be32 saddr, __be16 sport, - __be32 daddr, unsigned short hnum) +struct sock *inet_lookup_reuseport(struct net *net, struct sock *sk, + struct sk_buff *skb, int doff, + __be32 saddr, __be16 sport, + __be32 daddr, unsigned short hnum) { struct sock *reuse_sk = NULL; u32 phash; @@ -346,6 +346,7 @@ static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk, } return reuse_sk; } +EXPORT_SYMBOL_GPL(inet_lookup_reuseport);

/* * Here are some nice properties to exploit here. The BSD API @@ -369,8 +370,8 @@ static struct sock *inet_lhash2_lookup(struct net *net, sk_nulls_for_each_rcu(sk, node, &ilb2->nulls_head) { score = compute_score(sk, net, hnum, daddr, dif, sdif); if (score > hiscore) { - result = lookup_reuseport(net, sk, skb, doff, - saddr, sport, daddr, hnum); + result = inet_lookup_reuseport(net, sk, skb, doff, + saddr, sport, daddr, hnum); if (result) return result;

@@ -399,7 +400,7 @@ static inline struct sock *inet_lookup_run_bpf(struct net *net, if (no_reuseport || IS_ERR_OR_NULL(sk)) return sk;

- reuse_sk = lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum); + reuse_sk = inet_lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum); if (reuse_sk) sk = reuse_sk; return sk; diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c index b64b49012655..b7c56867314e 100644 --- a/net/ipv6/inet6_hashtables.c +++ b/net/ipv6/inet6_hashtables.c @@ -111,12 +111,12 @@ static inline int compute_score(struct sock *sk, struct net *net, return score; }

-static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk, - struct sk_buff *skb, int doff, - const struct in6_addr *saddr, - __be16 sport, - const struct in6_addr *daddr, - unsigned short hnum) +struct sock *inet6_lookup_reuseport(struct net *net, struct sock *sk, + struct sk_buff *skb, int doff, + const struct in6_addr *saddr, + __be16 sport, + const struct in6_addr *daddr, + unsigned short hnum) { struct sock *reuse_sk = NULL; u32 phash; @@ -127,6 +127,7 @@ static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk, } return reuse_sk; } +EXPORT_SYMBOL_GPL(inet6_lookup_reuseport);

/* called with rcu_read_lock() */ static struct sock *inet6_lhash2_lookup(struct net *net, @@ -143,8 +144,8 @@ static struct sock *inet6_lhash2_lookup(struct net *net, sk_nulls_for_each_rcu(sk, node, &ilb2->nulls_head) { score = compute_score(sk, net, hnum, daddr, dif, sdif); if (score > hiscore) { - result = lookup_reuseport(net, sk, skb, doff, - saddr, sport, daddr, hnum); + result = inet6_lookup_reuseport(net, sk, skb, doff, + saddr, sport, daddr, hnum); if (result) return result;

@@ -175,7 +176,7 @@ static inline struct sock *inet6_lookup_run_bpf(struct net *net, if (no_reuseport || IS_ERR_OR_NULL(sk)) return sk;

- reuse_sk = lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum); + reuse_sk = inet6_lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum); if (reuse_sk) sk = reuse_sk; return sk;

There are currently four copies of reuseport_lookup: one each for (TCP, UDP)x(IPv4, IPv6). This forces us to duplicate all callers of those functions as well. This is already the case for sk_lookup helpers (inet,inet6,udp4,udp6)_lookup_run_bpf.

The only difference between the reuseport_lookup helpers is calling a different hash function. Cut down the number of reuseport_lookup functions to one per IP version by using the INDIRECT_CALL infrastructure.

Signed-off-by: Lorenz Bauer lmb@isovalent.com --- include/net/inet6_hashtables.h | 11 ++++++++++- include/net/inet_hashtables.h | 15 +++++++++----- net/ipv4/inet_hashtables.c | 22 ++++++++++++++------- net/ipv4/udp.c | 37 +++++++++++----------------------- net/ipv6/inet6_hashtables.c | 16 +++++++++++---- net/ipv6/udp.c | 45 +++++++++++++++--------------------------- 6 files changed, 75 insertions(+), 71 deletions(-)

diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h index 032ddab48f8f..49d586454287 100644 --- a/include/net/inet6_hashtables.h +++ b/include/net/inet6_hashtables.h @@ -48,12 +48,21 @@ struct sock *__inet6_lookup_established(struct net *net, const u16 hnum, const int dif, const int sdif);

+typedef u32 (*inet6_ehashfn_t)(const struct net *net, + const struct in6_addr *laddr, const u16 lport, + const struct in6_addr *faddr, const __be16 fport); + +u32 inet6_ehashfn(const struct net *net, + const struct in6_addr *laddr, const u16 lport, + const struct in6_addr *faddr, const __be16 fport); + struct sock *inet6_lookup_reuseport(struct net *net, struct sock *sk, struct sk_buff *skb, int doff, const struct in6_addr *saddr, __be16 sport, const struct in6_addr *daddr, - unsigned short hnum); + unsigned short hnum, + inet6_ehashfn_t ehashfn);

struct sock *inet6_lookup_listener(struct net *net, struct inet_hashinfo *hashinfo, diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index 8734f3488f5d..51ab6a1a3601 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -379,10 +379,19 @@ struct sock *__inet_lookup_established(struct net *net, const __be32 daddr, const u16 hnum, const int dif, const int sdif);

+typedef u32 (*inet_ehashfn_t)(const struct net *net, + const __be32 laddr, const __u16 lport, + const __be32 faddr, const __be16 fport); + +u32 inet_ehashfn(const struct net *net, + const __be32 laddr, const __u16 lport, + const __be32 faddr, const __be16 fport); + struct sock *inet_lookup_reuseport(struct net *net, struct sock *sk, struct sk_buff *skb, int doff, __be32 saddr, __be16 sport, - __be32 daddr, unsigned short hnum); + __be32 daddr, unsigned short hnum, + inet_ehashfn_t ehashfn);

static inline struct sock * inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, @@ -453,10 +462,6 @@ static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, refcounted); }

-u32 inet6_ehashfn(const struct net *net, - const struct in6_addr *laddr, const u16 lport, - const struct in6_addr *faddr, const __be16 fport); - static inline void sk_daddr_set(struct sock *sk, __be32 addr) { sk->sk_daddr = addr; /* alias of inet_daddr */ diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 91f9210d4e83..1ec895fd9905 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -28,9 +28,9 @@ #include <net/tcp.h> #include <net/sock_reuseport.h>

-static u32 inet_ehashfn(const struct net *net, const __be32 laddr, - const __u16 lport, const __be32 faddr, - const __be16 fport) +u32 inet_ehashfn(const struct net *net, const __be32 laddr, + const __u16 lport, const __be32 faddr, + const __be16 fport) { static u32 inet_ehash_secret __read_mostly;

@@ -332,6 +332,10 @@ static inline int compute_score(struct sock *sk, struct net *net, return score; }

+INDIRECT_CALLABLE_DECLARE(u32 udp_ehashfn(const struct net *, + const __be32, const __u16, + const __be32, const __be16)); + /** * inet_lookup_reuseport() - execute reuseport logic on AF_INET socket if necessary. * @net: network namespace. @@ -342,6 +346,7 @@ static inline int compute_score(struct sock *sk, struct net *net, * @sport: source port. * @daddr: destination address. * @hnum: destination port in host byte order. + * @ehashfn: hash function used to generate the fallback hash. * * Return: NULL if sk doesn't have SO_REUSEPORT set, otherwise a pointer to * the selected sock or an error. @@ -349,13 +354,15 @@ static inline int compute_score(struct sock *sk, struct net *net, struct sock *inet_lookup_reuseport(struct net *net, struct sock *sk, struct sk_buff *skb, int doff, __be32 saddr, __be16 sport, - __be32 daddr, unsigned short hnum) + __be32 daddr, unsigned short hnum, + inet_ehashfn_t ehashfn) { struct sock *reuse_sk = NULL; u32 phash;

if (sk->sk_reuseport) { - phash = inet_ehashfn(net, daddr, hnum, saddr, sport); + phash = INDIRECT_CALL_2(ehashfn, inet_ehashfn, udp_ehashfn, + net, daddr, hnum, saddr, sport); reuse_sk = reuseport_select_sock(sk, phash, skb, doff); } return reuse_sk; @@ -385,7 +392,7 @@ static struct sock *inet_lhash2_lookup(struct net *net, score = compute_score(sk, net, hnum, daddr, dif, sdif); if (score > hiscore) { result = inet_lookup_reuseport(net, sk, skb, doff, - saddr, sport, daddr, hnum); + saddr, sport, daddr, hnum, inet_ehashfn); if (result) return result;

@@ -414,7 +421,8 @@ static inline struct sock *inet_lookup_run_bpf(struct net *net, if (no_reuseport || IS_ERR_OR_NULL(sk)) return sk;

- reuse_sk = inet_lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum); + reuse_sk = inet_lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum, + inet_ehashfn); if (reuse_sk) sk = reuse_sk; return sk; diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index fd3dae081f3a..10468fe144d0 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -405,9 +405,9 @@ static int compute_score(struct sock *sk, struct net *net, return score; }

-static u32 udp_ehashfn(const struct net *net, const __be32 laddr, - const __u16 lport, const __be32 faddr, - const __be16 fport) +INDIRECT_CALLABLE_SCOPE +u32 udp_ehashfn(const struct net *net, const __be32 laddr, const __u16 lport, + const __be32 faddr, const __be16 fport) { static u32 udp_ehash_secret __read_mostly;

@@ -417,22 +417,6 @@ static u32 udp_ehashfn(const struct net *net, const __be32 laddr, udp_ehash_secret + net_hash_mix(net)); }

-static struct sock *lookup_reuseport(struct net *net, struct sock *sk, - struct sk_buff *skb, - __be32 saddr, __be16 sport, - __be32 daddr, unsigned short hnum) -{ - struct sock *reuse_sk = NULL; - u32 hash; - - if (sk->sk_reuseport && sk->sk_state != TCP_ESTABLISHED) { - hash = udp_ehashfn(net, daddr, hnum, saddr, sport); - reuse_sk = reuseport_select_sock(sk, hash, skb, - sizeof(struct udphdr)); - } - return reuse_sk; -} - /* called with rcu_read_lock() */ static struct sock *udp4_lib_lookup2(struct net *net, __be32 saddr, __be16 sport, @@ -450,11 +434,13 @@ static struct sock *udp4_lib_lookup2(struct net *net, score = compute_score(sk, net, saddr, sport, daddr, hnum, dif, sdif); if (score > badness) { - result = lookup_reuseport(net, sk, skb, - saddr, sport, daddr, hnum); - /* Fall back to scoring if group has connections */ - if (result && !reuseport_has_conns(sk)) - return result; + if (sk->sk_state != TCP_ESTABLISHED) { + result = inet_lookup_reuseport(net, sk, skb, sizeof(struct udphdr), + saddr, sport, daddr, hnum, udp_ehashfn); + /* Fall back to scoring if group has connections */ + if (result && !reuseport_has_conns(sk)) + return result; + }

result = result ? : sk; badness = score; @@ -480,7 +466,8 @@ static struct sock *udp4_lookup_run_bpf(struct net *net, if (no_reuseport || IS_ERR_OR_NULL(sk)) return sk;

- reuse_sk = lookup_reuseport(net, sk, skb, saddr, sport, daddr, hnum); + reuse_sk = inet_lookup_reuseport(net, sk, skb, sizeof(struct udphdr), + saddr, sport, daddr, hnum, udp_ehashfn); if (reuse_sk) sk = reuse_sk; return sk; diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c index 208998694ae3..a350ee40141c 100644 --- a/net/ipv6/inet6_hashtables.c +++ b/net/ipv6/inet6_hashtables.c @@ -111,6 +111,10 @@ static inline int compute_score(struct sock *sk, struct net *net, return score; }

+INDIRECT_CALLABLE_DECLARE(u32 udp6_ehashfn(const struct net *, + const struct in6_addr *, const u16, + const struct in6_addr *, const __be16)); + /** * inet6_lookup_reuseport() - execute reuseport logic on AF_INET6 socket if necessary. * @net: network namespace. @@ -121,6 +125,7 @@ static inline int compute_score(struct sock *sk, struct net *net, * @sport: source port. * @daddr: destination address. * @hnum: destination port in host byte order. + * @ehashfn: hash function used to generate the fallback hash. * * Return: NULL if sk doesn't have SO_REUSEPORT set, otherwise a pointer to * the selected sock or an error. @@ -130,13 +135,15 @@ struct sock *inet6_lookup_reuseport(struct net *net, struct sock *sk, const struct in6_addr *saddr, __be16 sport, const struct in6_addr *daddr, - unsigned short hnum) + unsigned short hnum, + inet6_ehashfn_t ehashfn) { struct sock *reuse_sk = NULL; u32 phash;

if (sk->sk_reuseport) { - phash = inet6_ehashfn(net, daddr, hnum, saddr, sport); + phash = INDIRECT_CALL_2(ehashfn, inet6_ehashfn, udp6_ehashfn, + net, daddr, hnum, saddr, sport); reuse_sk = reuseport_select_sock(sk, phash, skb, doff); } return reuse_sk; @@ -159,7 +166,7 @@ static struct sock *inet6_lhash2_lookup(struct net *net, score = compute_score(sk, net, hnum, daddr, dif, sdif); if (score > hiscore) { result = inet6_lookup_reuseport(net, sk, skb, doff, - saddr, sport, daddr, hnum); + saddr, sport, daddr, hnum, inet6_ehashfn); if (result) return result;

@@ -190,7 +197,8 @@ static inline struct sock *inet6_lookup_run_bpf(struct net *net, if (no_reuseport || IS_ERR_OR_NULL(sk)) return sk;

- reuse_sk = inet6_lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum); + reuse_sk = inet6_lookup_reuseport(net, sk, skb, doff, + saddr, sport, daddr, hnum, inet6_ehashfn); if (reuse_sk) sk = reuse_sk; return sk; diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index e5a337e6b970..2af3a595f38a 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -70,11 +70,12 @@ int udpv6_init_sock(struct sock *sk) return 0; }

-static u32 udp6_ehashfn(const struct net *net, - const struct in6_addr *laddr, - const u16 lport, - const struct in6_addr *faddr, - const __be16 fport) +INDIRECT_CALLABLE_SCOPE +u32 udp6_ehashfn(const struct net *net, + const struct in6_addr *laddr, + const u16 lport, + const struct in6_addr *faddr, + const __be16 fport) { static u32 udp6_ehash_secret __read_mostly; static u32 udp_ipv6_hash_secret __read_mostly; @@ -159,24 +160,6 @@ static int compute_score(struct sock *sk, struct net *net, return score; }

-static struct sock *lookup_reuseport(struct net *net, struct sock *sk, - struct sk_buff *skb, - const struct in6_addr *saddr, - __be16 sport, - const struct in6_addr *daddr, - unsigned int hnum) -{ - struct sock *reuse_sk = NULL; - u32 hash; - - if (sk->sk_reuseport && sk->sk_state != TCP_ESTABLISHED) { - hash = udp6_ehashfn(net, daddr, hnum, saddr, sport); - reuse_sk = reuseport_select_sock(sk, hash, skb, - sizeof(struct udphdr)); - } - return reuse_sk; -} - /* called with rcu_read_lock() */ static struct sock *udp6_lib_lookup2(struct net *net, const struct in6_addr *saddr, __be16 sport, @@ -193,11 +176,14 @@ static struct sock *udp6_lib_lookup2(struct net *net, score = compute_score(sk, net, saddr, sport, daddr, hnum, dif, sdif); if (score > badness) { - result = lookup_reuseport(net, sk, skb, - saddr, sport, daddr, hnum); - /* Fall back to scoring if group has connections */ - if (result && !reuseport_has_conns(sk)) - return result; + if (sk->sk_state != TCP_ESTABLISHED) { + result = inet6_lookup_reuseport(net, sk, skb, sizeof(struct udphdr), + saddr, sport, daddr, hnum, + udp6_ehashfn); + /* Fall back to scoring if group has connections */ + if (result && !reuseport_has_conns(sk)) + return result; + }

result = result ? : sk; badness = score; @@ -225,7 +211,8 @@ static inline struct sock *udp6_lookup_run_bpf(struct net *net, if (no_reuseport || IS_ERR_OR_NULL(sk)) return sk;

- reuse_sk = lookup_reuseport(net, sk, skb, saddr, sport, daddr, hnum); + reuse_sk = inet6_lookup_reuseport(net, sk, skb, sizeof(struct udphdr), + saddr, sport, daddr, hnum, udp6_ehashfn); if (reuse_sk) sk = reuse_sk; return sk;

Currently the bpf_sk_assign helper in tc BPF context refuses SO_REUSEPORT sockets. This means we can't use the helper to steer traffic to Envoy, which configures SO_REUSEPORT on its sockets. In turn, we're blocked from removing TPROXY from our setup.

The reason that bpf_sk_assign refuses such sockets is that the bpf_sk_lookup helpers don't execute SK_REUSEPORT programs. Instead, one of the reuseport sockets is selected by hash. This could cause dispatch to the "wrong" socket:

sk = bpf_sk_lookup_tcp(...) // select SO_REUSEPORT by hash bpf_sk_assign(skb, sk) // SK_REUSEPORT wasn't executed

Fixing this isn't as simple as invoking SK_REUSEPORT from the lookup helpers unfortunately. In the tc context, L2 headers are at the start of the skb, while SK_REUSEPORT expects L3 headers instead.

Instead, we execute the SK_REUSEPORT program when the assigned socket is pulled out of the skb, further up the stack. This creates some trickiness with regards to refcounting as bpf_sk_assign will put both refcounted and RCU freed sockets in skb->sk. reuseport sockets are RCU freed. We can infer that the sk_assigned socket is RCU freed if the reuseport lookup succeeds, but convincing yourself of this fact isn't straight forward. Therefore we defensively check refcounting on the sk_assign sock even though it's probably not required in practice.

Fixes: 8e368dc72e86 ("bpf: Fix use of sk->sk_reuseport from sk_assign") Fixes: cf7fbe660f2d ("bpf: Add socket assign support") Co-developed-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Lorenz Bauer lmb@isovalent.com Cc: Joe Stringer joe@cilium.io Link: https://lore.kernel.org/bpf/CACAyw98+qycmpQzKupquhkxbvWK4OFyDuuLMBNROnfWMZxU... --- include/net/inet6_hashtables.h | 59 ++++++++++++++++++++++++++++++++++++++---- include/net/inet_hashtables.h | 52 +++++++++++++++++++++++++++++++++++-- include/net/sock.h | 7 +++-- include/uapi/linux/bpf.h | 3 --- net/core/filter.c | 2 -- net/ipv4/udp.c | 8 ++++-- net/ipv6/udp.c | 10 ++++--- tools/include/uapi/linux/bpf.h | 3 --- 8 files changed, 122 insertions(+), 22 deletions(-)

diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h index 4d2a1a3c0be7..4d300af6ccb6 100644 --- a/include/net/inet6_hashtables.h +++ b/include/net/inet6_hashtables.h @@ -103,6 +103,49 @@ static inline struct sock *__inet6_lookup(struct net *net, daddr, hnum, dif, sdif); }

+static inline +struct sock *inet6_steal_sock(struct net *net, struct sk_buff *skb, int doff, + const struct in6_addr *saddr, const __be16 sport, + const struct in6_addr *daddr, const __be16 dport, + bool *refcounted, inet6_ehashfn_t ehashfn) +{ + struct sock *sk, *reuse_sk; + bool prefetched; + + sk = skb_steal_sock(skb, refcounted, &prefetched); + if (!sk) + return NULL; + + if (!prefetched) + return sk; + + if (sk->sk_protocol == IPPROTO_TCP) { + if (sk->sk_state != TCP_LISTEN) + return sk; + } else if (sk->sk_protocol == IPPROTO_UDP) { + if (sk->sk_state != TCP_CLOSE) + return sk; + } else { + return sk; + } + + reuse_sk = inet6_lookup_reuseport(net, sk, skb, doff, + saddr, sport, daddr, ntohs(dport), + ehashfn); + if (!reuse_sk || reuse_sk == sk) + return sk; + + /* We've chosen a new reuseport sock which is never refcounted. + * sk might be refcounted however, drop the reference if necessary. + */ + if (*refcounted) { + sock_put(sk); + *refcounted = false; + } + + return reuse_sk; +} + static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo, struct sk_buff *skb, int doff, const __be16 sport, @@ -110,14 +153,20 @@ static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo, int iif, int sdif, bool *refcounted) { - struct sock *sk = skb_steal_sock(skb, refcounted); - + struct net *net = dev_net(skb_dst(skb)->dev); + const struct ipv6hdr *ip6h = ipv6_hdr(skb); + struct sock *sk; + + sk = inet6_steal_sock(net, skb, doff, &ip6h->saddr, sport, &ip6h->daddr, dport, + refcounted, inet6_ehashfn); + if (IS_ERR(sk)) + return NULL; if (sk) return sk;

- return __inet6_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb, - doff, &ipv6_hdr(skb)->saddr, sport, - &ipv6_hdr(skb)->daddr, ntohs(dport), + return __inet6_lookup(net, hashinfo, skb, + doff, &ip6h->saddr, sport, + &ip6h->daddr, ntohs(dport), iif, sdif, refcounted); }

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index aa02f1db1f86..2c405d9df300 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -449,6 +449,49 @@ static inline struct sock *inet_lookup(struct net *net, return sk; }

+static inline +struct sock *inet_steal_sock(struct net *net, struct sk_buff *skb, int doff, + const __be32 saddr, const __be16 sport, + const __be32 daddr, const __be16 dport, + bool *refcounted, inet_ehashfn_t ehashfn) +{ + struct sock *sk, *reuse_sk; + bool prefetched; + + sk = skb_steal_sock(skb, refcounted, &prefetched); + if (!sk) + return NULL; + + if (!prefetched) + return sk; + + if (sk->sk_protocol == IPPROTO_TCP) { + if (sk->sk_state != TCP_LISTEN) + return sk; + } else if (sk->sk_protocol == IPPROTO_UDP) { + if (sk->sk_state != TCP_CLOSE) + return sk; + } else { + return sk; + } + + reuse_sk = inet_lookup_reuseport(net, sk, skb, doff, + saddr, sport, daddr, ntohs(dport), + ehashfn); + if (!reuse_sk || reuse_sk == sk) + return sk; + + /* We've chosen a new reuseport sock which is never refcounted. + * sk might be refcounted however, drop the reference if necessary. + */ + if (*refcounted) { + sock_put(sk); + *refcounted = false; + } + + return reuse_sk; +} + static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, struct sk_buff *skb, int doff, @@ -457,13 +500,18 @@ static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, const int sdif, bool *refcounted) { - struct sock *sk = skb_steal_sock(skb, refcounted); + struct net *net = dev_net(skb_dst(skb)->dev); const struct iphdr *iph = ip_hdr(skb); + struct sock *sk;

+ sk = inet_steal_sock(net, skb, doff, iph->saddr, sport, iph->daddr, dport, + refcounted, inet_ehashfn); + if (IS_ERR(sk)) + return NULL; if (sk) return sk;

- return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb, + return __inet_lookup(net, hashinfo, skb, doff, iph->saddr, sport, iph->daddr, dport, inet_iif(skb), sdif, refcounted); diff --git a/include/net/sock.h b/include/net/sock.h index 656ea89f60ff..5645570c2a64 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2806,20 +2806,23 @@ sk_is_refcounted(struct sock *sk) * skb_steal_sock - steal a socket from an sk_buff * @skb: sk_buff to steal the socket from * @refcounted: is set to true if the socket is reference-counted + * @prefetched: is set to true if the socket was assigned from bpf */ static inline struct sock * -skb_steal_sock(struct sk_buff *skb, bool *refcounted) +skb_steal_sock(struct sk_buff *skb, bool *refcounted, bool *prefetched) { if (skb->sk) { struct sock *sk = skb->sk;

*refcounted = true; - if (skb_sk_is_prefetched(skb)) + *prefetched = skb_sk_is_prefetched(skb); + if (*prefetched) *refcounted = sk_is_refcounted(sk); skb->destructor = NULL; skb->sk = NULL; return sk; } + *prefetched = false; *refcounted = false; return NULL; } diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index a7b5e91dd768..d6fb6f43b0f3 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -4158,9 +4158,6 @@ union bpf_attr { * **-EOPNOTSUPP** if the operation is not supported, for example * a call from outside of TC ingress. * - * **-ESOCKTNOSUPPORT** if the socket type is not supported - * (reuseport). - * * long bpf_sk_assign(struct bpf_sk_lookup *ctx, struct bpf_sock *sk, u64 flags) * Description * Helper is overloaded depending on BPF program type. This diff --git a/net/core/filter.c b/net/core/filter.c index 428df050d021..d4be0a1d754c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7278,8 +7278,6 @@ BPF_CALL_3(bpf_sk_assign, struct sk_buff *, skb, struct sock *, sk, u64, flags) return -EOPNOTSUPP; if (unlikely(dev_net(skb->dev) != sock_net(sk))) return -ENETUNREACH; - if (unlikely(sk_fullsock(sk) && sk->sk_reuseport)) - return -ESOCKTNOSUPPORT; if (sk_is_refcounted(sk) && unlikely(!refcount_inc_not_zero(&sk->sk_refcnt))) return -ENOENT; diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 2500e92050a0..a3fa781432b9 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -2373,7 +2373,11 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, if (udp4_csum_init(skb, uh, proto)) goto csum_error;

- sk = skb_steal_sock(skb, &refcounted); + sk = inet_steal_sock(net, skb, sizeof(struct udphdr), saddr, uh->source, daddr, uh->dest, + &refcounted, udp_ehashfn); + if (IS_ERR(sk)) + goto no_sk; + if (sk) { struct dst_entry *dst = skb_dst(skb); int ret; @@ -2394,7 +2398,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable); if (sk) return udp_unicast_rcv_skb(sk, skb, uh); - +no_sk: if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) goto drop; nf_reset_ct(skb); diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 961b7e61f02c..0a90f34696ad 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -910,9 +910,9 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; const struct in6_addr *saddr, *daddr; struct net *net = dev_net(skb->dev); + bool refcounted; struct udphdr *uh; struct sock *sk; - bool refcounted; u32 ulen = 0;

if (!pskb_may_pull(skb, sizeof(struct udphdr))) @@ -949,7 +949,11 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, goto csum_error;

/* Check if the socket is already available, e.g. due to early demux */ - sk = skb_steal_sock(skb, &refcounted); + sk = inet6_steal_sock(net, skb, sizeof(struct udphdr), saddr, uh->source, daddr, uh->dest, + &refcounted, udp6_ehashfn); + if (IS_ERR(sk)) + goto no_sk; + if (sk) { struct dst_entry *dst = skb_dst(skb); int ret; @@ -983,7 +987,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, goto report_csum_error; return udp6_unicast_rcv_skb(sk, skb, uh); } - +no_sk: reason = SKB_DROP_REASON_NO_SOCKET;

if (!uh->check) diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index a7b5e91dd768..d6fb6f43b0f3 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -4158,9 +4158,6 @@ union bpf_attr { * **-EOPNOTSUPP** if the operation is not supported, for example * a call from outside of TC ingress. * - * **-ESOCKTNOSUPPORT** if the socket type is not supported - * (reuseport). - * * long bpf_sk_assign(struct bpf_sk_lookup *ctx, struct bpf_sock *sk, u64 flags) * Description * Helper is overloaded depending on BPF program type. This

From: Daniel Borkmann daniel@iogearbox.net

We use two programs to check that the new reuseport logic is executed appropriately.

The first is a TC clsact program which bpf_sk_assigns the skb to a UDP or TCP socket created by user space. Since the test communicates via lo we see both directions of packets in the eBPF. Traffic ingressing to the reuseport socket is identified by looking at the destination port. For TCP, we additionally need to make sure that we only assign the initial SYN packets towards our listening socket. The network stack then creates a request socket which transitions to ESTABLISHED after the 3WHS.

The second is a reuseport program which shares the fact that it has been executed with user space. This tells us that the delayed lookup mechanism is working.

Signed-off-by: Daniel Borkmann daniel@iogearbox.net Co-developed-by: Lorenz Bauer lmb@isovalent.com Signed-off-by: Lorenz Bauer lmb@isovalent.com Cc: Joe Stringer joe@cilium.io --- tools/testing/selftests/bpf/network_helpers.c | 3 + .../selftests/bpf/prog_tests/assign_reuse.c | 197 +++++++++++++++++++++ .../selftests/bpf/progs/test_assign_reuse.c | 142 +++++++++++++++ 3 files changed, 342 insertions(+)

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c index a105c0cd008a..8a33bcea97de 100644 --- a/tools/testing/selftests/bpf/network_helpers.c +++ b/tools/testing/selftests/bpf/network_helpers.c @@ -423,6 +423,9 @@ struct nstoken *open_netns(const char *name)

void close_netns(struct nstoken *token) { + if (!token) + return; + ASSERT_OK(setns(token->orig_netns_fd, CLONE_NEWNET), "setns"); close(token->orig_netns_fd); free(token); diff --git a/tools/testing/selftests/bpf/prog_tests/assign_reuse.c b/tools/testing/selftests/bpf/prog_tests/assign_reuse.c new file mode 100644 index 000000000000..622f123410f4 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/assign_reuse.c @@ -0,0 +1,197 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2023 Isovalent */ +#include <uapi/linux/if_link.h> +#include <test_progs.h> + +#include <netinet/tcp.h> +#include <netinet/udp.h> + +#include "network_helpers.h" +#include "test_assign_reuse.skel.h" + +#define NS_TEST "assign_reuse" +#define LOOPBACK 1 +#define PORT 4443 + +static int attach_reuseport(int sock_fd, int prog_fd) +{ + return setsockopt(sock_fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_EBPF, + &prog_fd, sizeof(prog_fd)); +} + +static __u64 cookie(int fd) +{ + __u64 cookie = 0; + socklen_t cookie_len = sizeof(cookie); + int ret; + + ret = getsockopt(fd, SOL_SOCKET, SO_COOKIE, &cookie, &cookie_len); + ASSERT_OK(ret, "cookie"); + ASSERT_GT(cookie, 0, "cookie_invalid"); + + return cookie; +} + +static int echo_test_udp(int fd_sv) +{ + struct sockaddr_storage addr = {}; + socklen_t len = sizeof(addr); + char buff[1] = {}; + int fd_cl = -1, ret; + + fd_cl = connect_to_fd(fd_sv, 100); + ASSERT_GT(fd_cl, 0, "create_client"); + ASSERT_EQ(getsockname(fd_cl, (void *)&addr, &len), 0, "getsockname"); + + ASSERT_EQ(send(fd_cl, buff, sizeof(buff), 0), 1, "send_client"); + + ret = recv(fd_sv, buff, sizeof(buff), 0); + if (ret < 0) + return errno; + + ASSERT_EQ(ret, 1, "recv_server"); + ASSERT_EQ(sendto(fd_sv, buff, sizeof(buff), 0, (void *)&addr, len), 1, "send_server"); + ASSERT_EQ(recv(fd_cl, buff, sizeof(buff), 0), 1, "recv_client"); + close(fd_cl); + return 0; +} + +static int echo_test_tcp(int fd_sv) +{ + char buff[1] = {}; + int fd_cl = -1, fd_sv_cl = -1; + + fd_cl = connect_to_fd(fd_sv, 100); + if (fd_cl < 0) + return errno; + + fd_sv_cl = accept(fd_sv, NULL, NULL); + ASSERT_GE(fd_sv_cl, 0, "accept_fd"); + + ASSERT_EQ(send(fd_cl, buff, sizeof(buff), 0), 1, "send_client"); + ASSERT_EQ(recv(fd_sv_cl, buff, sizeof(buff), 0), 1, "recv_server"); + ASSERT_EQ(send(fd_sv_cl, buff, sizeof(buff), 0), 1, "send_server"); + ASSERT_EQ(recv(fd_cl, buff, sizeof(buff), 0), 1, "recv_client"); + close(fd_sv_cl); + close(fd_cl); + return 0; +} + +void run_assign_reuse(int family, int sotype, const char *ip, __u16 port) +{ + DECLARE_LIBBPF_OPTS(bpf_tc_hook, tc_hook, + .ifindex = LOOPBACK, + .attach_point = BPF_TC_INGRESS, + ); + DECLARE_LIBBPF_OPTS(bpf_tc_opts, tc_opts, + .handle = 1, + .priority = 1, + ); + bool hook_created = false, tc_attached = false; + int ret, fd_tc, fd_accept, fd_drop, fd_map; + int *fd_sv = NULL; + __u64 fd_val; + struct test_assign_reuse *skel; + const int zero = 0; + + skel = test_assign_reuse__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + goto cleanup; + + skel->rodata->dest_port = port; + + ret = test_assign_reuse__load(skel); + if (!ASSERT_OK(ret, "skel_load")) + goto cleanup; + + ASSERT_EQ(skel->bss->sk_cookie_seen, 0, "cookie_init"); + + fd_tc = bpf_program__fd(skel->progs.tc_main); + fd_accept = bpf_program__fd(skel->progs.reuse_accept); + fd_drop = bpf_program__fd(skel->progs.reuse_drop); + fd_map = bpf_map__fd(skel->maps.sk_map); + + fd_sv = start_reuseport_server(family, sotype, ip, port, 100, 1); + if (!ASSERT_NEQ(fd_sv, NULL, "start_reuseport_server")) + goto cleanup; + + ret = attach_reuseport(*fd_sv, fd_drop); + if (!ASSERT_OK(ret, "attach_reuseport")) + goto cleanup; + + fd_val = *fd_sv; + ret = bpf_map_update_elem(fd_map, &zero, &fd_val, BPF_NOEXIST); + if (!ASSERT_OK(ret, "bpf_sk_map")) + goto cleanup; + + ret = bpf_tc_hook_create(&tc_hook); + if (ret == 0) + hook_created = true; + ret = ret == -EEXIST ? 0 : ret; + if (!ASSERT_OK(ret, "bpf_tc_hook_create")) + goto cleanup; + + tc_opts.prog_fd = fd_tc; + ret = bpf_tc_attach(&tc_hook, &tc_opts); + if (!ASSERT_OK(ret, "bpf_tc_attach")) + goto cleanup; + tc_attached = true; + + if (sotype == SOCK_STREAM) + ASSERT_EQ(echo_test_tcp(*fd_sv), ECONNREFUSED, "drop_tcp"); + else + ASSERT_EQ(echo_test_udp(*fd_sv), EAGAIN, "drop_udp"); + ASSERT_EQ(skel->bss->reuseport_executed, 1, "program executed once"); + + skel->bss->sk_cookie_seen = 0; + skel->bss->reuseport_executed = 0; + ASSERT_OK(attach_reuseport(*fd_sv, fd_accept), "attach_reuseport(accept)"); + + if (sotype == SOCK_STREAM) + ASSERT_EQ(echo_test_tcp(*fd_sv), 0, "echo_tcp"); + else + ASSERT_EQ(echo_test_udp(*fd_sv), 0, "echo_udp"); + + ASSERT_EQ(skel->bss->sk_cookie_seen, cookie(*fd_sv), + "cookie_mismatch"); + ASSERT_EQ(skel->bss->reuseport_executed, 1, "program executed once"); +cleanup: + if (tc_attached) { + tc_opts.flags = tc_opts.prog_fd = tc_opts.prog_id = 0; + ret = bpf_tc_detach(&tc_hook, &tc_opts); + ASSERT_OK(ret, "bpf_tc_detach"); + } + if (hook_created) { + tc_hook.attach_point = BPF_TC_INGRESS | BPF_TC_EGRESS; + bpf_tc_hook_destroy(&tc_hook); + } + test_assign_reuse__destroy(skel); + free_fds(fd_sv, 1); +} + +void test_assign_reuse(void) +{ + struct nstoken *tok = NULL; + + SYS(out, "ip netns add %s", NS_TEST); + SYS(cleanup, "ip -net %s link set dev lo up", NS_TEST); + + tok = open_netns(NS_TEST); + if (!ASSERT_OK_PTR(tok, "netns token")) + return; + + if (test__start_subtest("tcpv4")) + run_assign_reuse(AF_INET, SOCK_STREAM, "127.0.0.1", PORT); + if (test__start_subtest("tcpv6")) + run_assign_reuse(AF_INET6, SOCK_STREAM, "::1", PORT); + if (test__start_subtest("udpv4")) + run_assign_reuse(AF_INET, SOCK_DGRAM, "127.0.0.1", PORT); + if (test__start_subtest("udpv6")) + run_assign_reuse(AF_INET6, SOCK_DGRAM, "::1", PORT); + +cleanup: + close_netns(tok); + SYS_NOFAIL("ip netns delete %s", NS_TEST); +out: + return; +} diff --git a/tools/testing/selftests/bpf/progs/test_assign_reuse.c b/tools/testing/selftests/bpf/progs/test_assign_reuse.c new file mode 100644 index 000000000000..4f2e2321ea06 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_assign_reuse.c @@ -0,0 +1,142 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2023 Isovalent */ +#include <stdbool.h> +#include <linux/bpf.h> +#include <linux/if_ether.h> +#include <linux/in.h> +#include <linux/ip.h> +#include <linux/ipv6.h> +#include <linux/tcp.h> +#include <linux/udp.h> +#include <bpf/bpf_endian.h> +#include <bpf/bpf_helpers.h> +#include <linux/pkt_cls.h> + +char LICENSE[] SEC("license") = "GPL"; + +__u64 sk_cookie_seen; +__u64 reuseport_executed; +union { + struct tcphdr tcp; + struct udphdr udp; +} headers; + +const volatile __u16 dest_port; + +struct { + __uint(type, BPF_MAP_TYPE_SOCKMAP); + __uint(max_entries, 1); + __type(key, __u32); + __type(value, __u64); +} sk_map SEC(".maps"); + +SEC("sk_reuseport") +int reuse_accept(struct sk_reuseport_md *ctx) +{ + reuseport_executed++; + + if (ctx->ip_protocol == IPPROTO_TCP) { + if (ctx->data + sizeof(headers.tcp) > ctx->data_end) + return SK_DROP; + + if (__builtin_memcmp(&headers.tcp, ctx->data, sizeof(headers.tcp)) != 0) + return SK_DROP; + } else if (ctx->ip_protocol == IPPROTO_UDP) { + if (ctx->data + sizeof(headers.udp) > ctx->data_end) + return SK_DROP; + + if (__builtin_memcmp(&headers.udp, ctx->data, sizeof(headers.udp)) != 0) + return SK_DROP; + } else { + return SK_DROP; + } + + sk_cookie_seen = bpf_get_socket_cookie(ctx->sk); + return SK_PASS; +} + +SEC("sk_reuseport") +int reuse_drop(struct sk_reuseport_md *ctx) +{ + reuseport_executed++; + sk_cookie_seen = 0; + return SK_DROP; +} + +static int +assign_sk(struct __sk_buff *skb) +{ + int zero = 0, ret = 0; + struct bpf_sock *sk; + + sk = bpf_map_lookup_elem(&sk_map, &zero); + if (!sk) + return TC_ACT_SHOT; + ret = bpf_sk_assign(skb, sk, 0); + bpf_sk_release(sk); + return ret ? TC_ACT_SHOT : TC_ACT_OK; +} + +static bool +maybe_assign_tcp(struct __sk_buff *skb, struct tcphdr *th) +{ + if (th + 1 > (void *)(long)(skb->data_end)) + return TC_ACT_SHOT; + + if (!th->syn || th->ack || th->dest != bpf_htons(dest_port)) + return TC_ACT_OK; + + __builtin_memcpy(&headers.tcp, th, sizeof(headers.tcp)); + return assign_sk(skb); +} + +static bool +maybe_assign_udp(struct __sk_buff *skb, struct udphdr *uh) +{ + if (uh + 1 > (void *)(long)(skb->data_end)) + return TC_ACT_SHOT; + + if (uh->dest != bpf_htons(dest_port)) + return TC_ACT_OK; + + __builtin_memcpy(&headers.udp, uh, sizeof(headers.udp)); + return assign_sk(skb); +} + +SEC("tc") +int tc_main(struct __sk_buff *skb) +{ + void *data_end = (void *)(long)skb->data_end; + void *data = (void *)(long)skb->data; + struct ethhdr *eth; + + eth = (struct ethhdr *)(data); + if (eth + 1 > data_end) + return TC_ACT_SHOT; + + if (eth->h_proto == bpf_htons(ETH_P_IP)) { + struct iphdr *iph = (struct iphdr *)(data + sizeof(*eth)); + + if (iph + 1 > data_end) + return TC_ACT_SHOT; + + if (iph->protocol == IPPROTO_TCP) + return maybe_assign_tcp(skb, (struct tcphdr *)(iph + 1)); + else if (iph->protocol == IPPROTO_UDP) + return maybe_assign_udp(skb, (struct udphdr *)(iph + 1)); + else + return TC_ACT_SHOT; + } else { + struct ipv6hdr *ip6h = (struct ipv6hdr *)(data + sizeof(*eth)); + + if (ip6h + 1 > data_end) + return TC_ACT_SHOT; + + if (ip6h->nexthdr == IPPROTO_TCP) + return maybe_assign_tcp(skb, (struct tcphdr *)(ip6h + 1)); + else if (ip6h->nexthdr == IPPROTO_UDP) + return maybe_assign_udp(skb, (struct udphdr *)(ip6h + 1)); + else + return TC_ACT_SHOT; + } +}