[MPTCP] [PATCH v2 10/25] tcp_extra_options: Extend tcp_extra_options_write

The sk in tcp_extra_options_write cannot be a const, because we need to be able to modify it (see TCP_MD5 in tcp_transmit_skb). In tcp_v4_send_ack/reset (and the v6 counterpart), we also need the original skb that triggers the response. Further, the sk must be a const here. So, we need a new tcp_extra_options_response_write callback to handle these cases. It's also cleaner IMO as these responses are quite different from tcp_options_write. Signed-off-by: Christoph Paasch <cpaasch(a)apple.com&gt; --- include/net/tcp.h | 13 +++++++++++-- net/ipv4/tcp.c | 22 +++++++++++++++++++++- net/ipv4/tcp_ipv4.c | 4 ++-- net/ipv4/tcp_output.c | 2 +- net/ipv6/tcp_ipv6.c | 2 +- 5 files changed, 36 insertions(+), 7 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index fff0959dfd91..0981a1b429ca 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -2081,7 +2081,11 @@ struct tcp_extra_option_ops { struct tcp_out_options *opts, const struct sock *sk); void (*write)(__be32 *ptr, struct sk_buff *skb, - struct tcp_out_options *opts, const struct sock *sk); + struct tcp_out_options *opts, struct sock *sk); + void (*response_write)(__be32 *ptr, struct sk_buff *orig, + struct tcphdr *th, + struct tcp_out_options *opts, + const struct sock *sk); int (*add_header_len)(const struct sock *listener, const struct sock *sk); struct module *owner; @@ -2099,7 +2103,12 @@ unsigned int tcp_extra_options_prepare(struct sk_buff *skb, u8 flags, void tcp_extra_options_write(__be32 *ptr, struct sk_buff *skb, struct tcp_out_options *opts, - const struct sock *sk); + struct sock *sk); + +void tcp_extra_options_response_write(__be32 *ptr, struct sk_buff *orig, + struct tcphdr *th, + struct tcp_out_options *opts, + const struct sock *sk); int tcp_extra_options_add_header(const struct sock *listener, const struct sock *sk); diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 155bee4659fa..487f28222d3c 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3539,7 +3539,7 @@ EXPORT_SYMBOL_GPL(tcp_extra_options_prepare); */ void tcp_extra_options_write(__be32 *ptr, struct sk_buff *skb, struct tcp_out_options *opts, - const struct sock *sk) + struct sock *sk) { struct tcp_extra_option_ops *entry; @@ -3552,6 +3552,26 @@ void tcp_extra_options_write(__be32 *ptr, struct sk_buff *skb, } EXPORT_SYMBOL_GPL(tcp_extra_options_write); +/* The RCU read lock must be held before calling, and should span both + * the call to tcp_extra_options_write and this function to ensure that + * tcp_option_list does not change between the two calls. + */ +void tcp_extra_options_response_write(__be32 *ptr, struct sk_buff *orig, + struct tcphdr *th, + struct tcp_out_options *opts, + const struct sock *sk) +{ + struct tcp_extra_option_ops *entry; + + list_for_each_entry_rcu(entry, &tcp_option_list, list) { + if (unlikely(!entry->write)) + continue; + + entry->response_write(ptr, orig, th, opts, sk); + } +} +EXPORT_SYMBOL_GPL(tcp_extra_options_response_write); + int tcp_extra_options_add_header(const struct sock *listener, const struct sock *sk) { diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index ccbb219c7b61..f717069ad778 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -696,7 +696,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb) used = tcp_extra_options_prepare(NULL, TCPHDR_RST, remaining, &opts, sk); - tcp_extra_options_write(&rep.opt[0], NULL, &opts, sk); + tcp_extra_options_response_write(&rep.opt[0], skb, &rep.th, &opts, sk); rcu_read_unlock(); arg.iov[0].iov_len += used; @@ -829,7 +829,7 @@ static void tcp_v4_send_ack(const struct sock *sk, used = tcp_extra_options_prepare(NULL, TCPHDR_ACK, remaining, &opts, sk); - tcp_extra_options_write(&rep.opt[offset], NULL, &opts, sk); + tcp_extra_options_response_write(&rep.opt[offset], skb, &rep.th, &opts, sk); rcu_read_unlock(); arg.iov[0].iov_len += used; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 199a8baf281c..1fd331018e58 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -527,7 +527,7 @@ static void tcp_options_write(__be32 *ptr, struct sk_buff *skb, struct sock *sk, smc_options_write(ptr, &options); if (static_branch_unlikely(&tcp_extra_options_enabled)) - tcp_extra_options_write(ptr, skb, opts, tcp_to_sk(tp)); + tcp_extra_options_write(ptr, skb, opts, sk); } static void smc_set_option(const struct tcp_sock *tp, diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 7e4e8788943f..ef037990ea5e 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -896,7 +896,7 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32 #endif if (static_branch_unlikely(&tcp_extra_options_enabled)) - tcp_extra_options_write(topt, buff, &extraopts, sk); + tcp_extra_options_response_write(topt, skb, t1, &extraopts, sk); memset(&fl6, 0, sizeof(fl6)); fl6.daddr = ipv6_hdr(skb)->saddr; -- 2.15.0