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Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Jonathan Corbet , Andrew Lunn Cc: Saeed Mahameed , Leon Romanovsky , Tariq Toukan , Boris Pismenny , Kuniyuki Iwashima , Willem de Bruijn , David Ahern , Neal Cardwell , Patrisious Haddad , Raed Salem , Jianbo Liu , Dragos Tatulea , Rahul Rameshbabu , Stanislav Fomichev , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Alexander Lobakin , Kiran Kella , Jacob Keller , netdev@vger.kernel.org Subject: [PATCH net-next v10 09/19] net: psp: update the TCP MSS to reflect PSP packet overhead Date: Thu, 28 Aug 2025 09:29:35 -0700 Message-ID: <20250828162953.2707727-10-daniel.zahka@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20250828162953.2707727-1-daniel.zahka@gmail.com> References: <20250828162953.2707727-1-daniel.zahka@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jakub Kicinski PSP eats 32B of header space. Adjust MSS appropriately. We can either modify tcp_mtu_to_mss() / tcp_mss_to_mtu() or reuse icsk_ext_hdr_len. The former option is more TCP specific and has runtime overhead. The latter is a bit of a hack as PSP is not an ext_hdr. If one squints hard enough, UDP encap is just a more practical version of IPv6 exthdr, so go with the latter. Happy to change. Reviewed-by: Willem de Bruijn Signed-off-by: Jakub Kicinski Signed-off-by: Daniel Zahka --- Notes: v6: - make psp_sk_overhead() add 40B of encapsulation overhead. v1: - https://lore.kernel.org/netdev/20240510030435.120935-8-kuba@kernel.org/ include/net/psp/functions.h | 14 ++++++++++++++ include/net/psp/types.h | 3 +++ net/ipv4/tcp_ipv4.c | 4 ++-- net/ipv6/ipv6_sockglue.c | 6 +++++- net/ipv6/tcp_ipv6.c | 6 +++--- net/psp/psp_sock.c | 5 +++++ 6 files changed, 32 insertions(+), 6 deletions(-) diff --git a/include/net/psp/functions.h b/include/net/psp/functions.h index bf703dcf353f..958c50dad34d 100644 --- a/include/net/psp/functions.h +++ b/include/net/psp/functions.h @@ -5,6 +5,7 @@ #include #include +#include #include #include #include @@ -139,6 +140,14 @@ static inline struct psp_assoc *psp_skb_get_assoc_rcu(struct sk_buff *skb) return psp_sk_get_assoc_rcu(skb->sk); } + +static inline unsigned int psp_sk_overhead(const struct sock *sk) +{ + int psp_encap = sizeof(struct udphdr) + PSP_HDR_SIZE + PSP_TRL_SIZE; + bool has_psp = rcu_access_pointer(sk->psp_assoc); + + return has_psp ? psp_encap : 0; +} #else static inline void psp_sk_assoc_free(struct sock *sk) { } static inline void @@ -178,6 +187,11 @@ static inline struct psp_assoc *psp_skb_get_assoc_rcu(struct sk_buff *skb) { return NULL; } + +static inline unsigned int psp_sk_overhead(const struct sock *sk) +{ + return 0; +} #endif static inline unsigned long diff --git a/include/net/psp/types.h b/include/net/psp/types.h index b0e32e7165a3..f93ad0e6c04f 100644 --- a/include/net/psp/types.h +++ b/include/net/psp/types.h @@ -93,6 +93,9 @@ struct psp_dev_caps { #define PSP_MAX_KEY 32 +#define PSP_HDR_SIZE 16 /* We don't support optional fields, yet */ +#define PSP_TRL_SIZE 16 /* AES-GCM/GMAC trailer size */ + struct psp_skb_ext { __be32 spi; u16 dev_id; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index f046e33f4c87..d5f19059c9b2 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -293,9 +293,9 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) inet->inet_dport = usin->sin_port; sk_daddr_set(sk, daddr); - inet_csk(sk)->icsk_ext_hdr_len = 0; + inet_csk(sk)->icsk_ext_hdr_len = psp_sk_overhead(sk); if (inet_opt) - inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; + inet_csk(sk)->icsk_ext_hdr_len += inet_opt->opt.optlen; tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT; diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index e66ec623972e..a61e742794f9 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -49,6 +49,7 @@ #include #include #include +#include #include @@ -107,7 +108,10 @@ struct ipv6_txoptions *ipv6_update_options(struct sock *sk, !((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) && inet_sk(sk)->inet_daddr != LOOPBACK4_IPV6) { struct inet_connection_sock *icsk = inet_csk(sk); - icsk->icsk_ext_hdr_len = opt->opt_flen + opt->opt_nflen; + + icsk->icsk_ext_hdr_len = + psp_sk_overhead(sk) + + opt->opt_flen + opt->opt_nflen; icsk->icsk_sync_mss(sk, icsk->icsk_pmtu_cookie); } } diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 7a88f67820a1..da1147509cab 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -302,10 +302,10 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr, sk->sk_gso_type = SKB_GSO_TCPV6; ip6_dst_store(sk, dst, NULL, NULL); - icsk->icsk_ext_hdr_len = 0; + icsk->icsk_ext_hdr_len = psp_sk_overhead(sk); if (opt) - icsk->icsk_ext_hdr_len = opt->opt_flen + - opt->opt_nflen; + icsk->icsk_ext_hdr_len += opt->opt_flen + + opt->opt_nflen; tp->rx_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr); diff --git a/net/psp/psp_sock.c b/net/psp/psp_sock.c index 9b761d186e80..66abf160e16c 100644 --- a/net/psp/psp_sock.c +++ b/net/psp/psp_sock.c @@ -180,6 +180,7 @@ int psp_sock_assoc_set_tx(struct sock *sk, struct psp_dev *psd, u32 version, struct psp_key_parsed *key, struct netlink_ext_ack *extack) { + struct inet_connection_sock *icsk; struct psp_assoc *pas, *dummy; int err; @@ -236,6 +237,10 @@ int psp_sock_assoc_set_tx(struct sock *sk, struct psp_dev *psd, tcp_write_collapse_fence(sk); pas->upgrade_seq = tcp_sk(sk)->rcv_nxt; + icsk = inet_csk(sk); + icsk->icsk_ext_hdr_len += psp_sk_overhead(sk); + icsk->icsk_sync_mss(sk, icsk->icsk_pmtu_cookie); + exit_free_dummy: kfree(dummy); exit_unlock: -- 2.47.3