Re: [PATCH bpf-next v4 3/7] net: remove duplicate reuseport_lookup functions

From: Kuniyuki Iwashima
Date: Wed Jun 28 2023 - 14:33:25 EST

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In reply to: Lorenz Bauer: "[PATCH bpf-next v4 3/7] net: remove duplicate reuseport_lookup functions"
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From: Lorenz Bauer <lmb@xxxxxxxxxxxxx>
Date: Wed, 28 Jun 2023 10:48:18 +0100
> 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.
>
> There are two differences between the reuseport_lookup helpers:
>
> 1. They call different hash functions depending on protocol
> 2. UDP reuseport_lookup checks that sk_state != TCP_ESTABLISHED
>
> Move the check for sk_state into the caller and use the INDIRECT_CALL
> infrastructure to cut down the helpers to one per IP version.
>
> Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxx>

Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>

2 nits below.

> ---
> include/net/inet6_hashtables.h | 11 ++++++++++-
> include/net/inet_hashtables.h | 15 ++++++++++-----
> net/ipv4/inet_hashtables.c | 20 +++++++++++++-------
> net/ipv4/udp.c | 34 +++++++++++++---------------------
> net/ipv6/inet6_hashtables.c | 14 ++++++++++----
> net/ipv6/udp.c | 41 ++++++++++++++++-------------------------
> 6 files changed, 72 insertions(+), 63 deletions(-)
>
> diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h
> index 032ddab48f8f..f89320b6fee3 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);
> +
> +inet6_ehashfn_t inet6_ehashfn;
> +
> +INDIRECT_CALLABLE_DECLARE(inet6_ehashfn_t udp6_ehashfn);

We need not define udp6_ehashfn() here as inet6_hashtables.c has
the definition.

Only inet6_ehashfn() is needed because sk_ehashfn() uses it.

> +
> 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..ddfa2e67fdb5 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);
> +
> +inet_ehashfn_t inet_ehashfn;
> +
> +INDIRECT_CALLABLE_DECLARE(inet_ehashfn_t udp_ehashfn);
> +

We don't need inet_ehashfn() and udp_ehashfn() declarations here.

> 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 920131e4a65d..352eb371c93b 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;
>
> @@ -39,6 +39,7 @@ static u32 inet_ehashfn(const struct net *net, const __be32 laddr,
> return __inet_ehashfn(laddr, lport, faddr, fport,
> inet_ehash_secret + net_hash_mix(net));
> }
> +EXPORT_SYMBOL_GPL(inet_ehashfn);
>
> /* This function handles inet_sock, but also timewait and request sockets
> * for IPv4/IPv6.
> @@ -332,16 +333,20 @@ static inline int compute_score(struct sock *sk, struct net *net,
> return score;
> }
>
> +INDIRECT_CALLABLE_DECLARE(inet_ehashfn_t udp_ehashfn);
> +
> 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, udp_ehashfn, inet_ehashfn,
> + net, daddr, hnum, saddr, sport);
> reuse_sk = reuseport_select_sock(sk, phash, skb, doff);
> }
> return reuse_sk;
> @@ -371,7 +376,7 @@ 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;
>
> @@ -400,7 +405,8 @@ 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 5ef478d2c408..7258edece691 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,
> @@ -451,7 +435,14 @@ static struct sock *udp4_lib_lookup2(struct net *net,
> daddr, hnum, dif, sdif);
> if (score > badness) {
> badness = score;
> - result = lookup_reuseport(net, sk, skb, saddr, sport, daddr, hnum);
> +
> + if (sk->sk_state == TCP_ESTABLISHED) {
> + result = sk;
> + continue;
> + }
> +
> + result = inet_lookup_reuseport(net, sk, skb, sizeof(struct udphdr),
> + saddr, sport, daddr, hnum, udp_ehashfn);
> if (!result) {
> result = sk;
> continue;
> @@ -490,7 +481,8 @@ 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 b7c56867314e..3616225c89ef 100644
> --- a/net/ipv6/inet6_hashtables.c
> +++ b/net/ipv6/inet6_hashtables.c
> @@ -39,6 +39,7 @@ u32 inet6_ehashfn(const struct net *net,
> return __inet6_ehashfn(lhash, lport, fhash, fport,
> inet6_ehash_secret + net_hash_mix(net));
> }
> +EXPORT_SYMBOL_GPL(inet6_ehashfn);
>
> /*
> * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
> @@ -111,18 +112,22 @@ static inline int compute_score(struct sock *sk, struct net *net,
> return score;
> }
>
> +INDIRECT_CALLABLE_DECLARE(inet6_ehashfn_t udp6_ehashfn);
> +
> 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 *reuse_sk = NULL;
> u32 phash;
>
> if (sk->sk_reuseport) {
> - phash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
> + phash = INDIRECT_CALL_INET(ehashfn, udp6_ehashfn, inet6_ehashfn,
> + net, daddr, hnum, saddr, sport);
> reuse_sk = reuseport_select_sock(sk, phash, skb, doff);
> }
> return reuse_sk;
> @@ -145,7 +150,7 @@ 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;
>
> @@ -176,7 +181,8 @@ 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 8b3cb1d7da7c..ebac9200b15c 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,
> @@ -194,7 +177,14 @@ static struct sock *udp6_lib_lookup2(struct net *net,
> daddr, hnum, dif, sdif);
> if (score > badness) {
> badness = score;
> - result = lookup_reuseport(net, sk, skb, saddr, sport, daddr, hnum);
> +
> + if (sk->sk_state == TCP_ESTABLISHED) {
> + result = sk;
> + continue;
> + }
> +
> + result = inet6_lookup_reuseport(net, sk, skb, sizeof(struct udphdr),
> + saddr, sport, daddr, hnum, udp6_ehashfn);
> if (!result) {
> result = sk;
> continue;
> @@ -234,7 +224,8 @@ 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;
>
> --
> 2.40.1

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In reply to: Lorenz Bauer: "[PATCH bpf-next v4 3/7] net: remove duplicate reuseport_lookup functions"
Next in thread: Lorenz Bauer: "[PATCH bpf-next v4 6/7] bpf, net: Support SO_REUSEPORT sockets with bpf_sk_assign"
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