[PATCH net-next v2 1/2] inet_diag: allow protocols to provide additional data

[PATCH net-next v2 1/2] inet_diag: allow protocols to provide additional data

[Ivan Delalande]

Extend inet_diag_handler to allow individual protocols to report
additional data on INET_DIAG_INFO through idiag_get_aux. The size
can be dynamic and is computed by idiag_get_aux_size.

Signed-off-by: Ivan Delalande <colona@arista.com>
---
 include/linux/inet_diag.h |  7 +++++++
 net/ipv4/inet_diag.c      | 22 ++++++++++++++++++----
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/include/linux/inet_diag.h b/include/linux/inet_diag.h
index 65da430e260f..ee251c585854 100644
--- a/include/linux/inet_diag.h
+++ b/include/linux/inet_diag.h
@@ -25,6 +25,13 @@ struct inet_diag_handler {
 					  struct inet_diag_msg *r,
 					  void *info);
 
+	int		(*idiag_get_aux)(struct sock *sk,
+					 bool net_admin,
+					 struct sk_buff *skb);
+
+	size_t		(*idiag_get_aux_size)(struct sock *sk,
+					      bool net_admin);
+
 	int		(*destroy)(struct sk_buff *in_skb,
 				   const struct inet_diag_req_v2 *req);
 
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 67325d5832d7..8a88ef373395 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -93,8 +93,17 @@ void inet_diag_msg_common_fill(struct inet_diag_msg *r, struct sock *sk)
 }
 EXPORT_SYMBOL_GPL(inet_diag_msg_common_fill);
 
-static size_t inet_sk_attr_size(void)
+static size_t inet_sk_attr_size(struct sock *sk,
+				const struct inet_diag_req_v2 *req,
+				bool net_admin)
 {
+	const struct inet_diag_handler *handler;
+	size_t aux = 0;
+
+	handler = inet_diag_table[req->sdiag_protocol];
+	if (handler && handler->idiag_get_aux_size)
+		aux = handler->idiag_get_aux_size(sk, net_admin);
+
 	return	  nla_total_size(sizeof(struct tcp_info))
 		+ nla_total_size(1) /* INET_DIAG_SHUTDOWN */
 		+ nla_total_size(1) /* INET_DIAG_TOS */
@@ -105,6 +114,7 @@ static size_t inet_sk_attr_size(void)
 		+ nla_total_size(SK_MEMINFO_VARS * sizeof(u32))
 		+ nla_total_size(TCP_CA_NAME_MAX)
 		+ nla_total_size(sizeof(struct tcpvegas_info))
+		+ nla_total_size(aux)
 		+ 64;
 }
 
@@ -260,6 +270,10 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
 
 	handler->idiag_get_info(sk, r, info);
 
+	if (ext & (1 << (INET_DIAG_INFO - 1)) && handler->idiag_get_aux)
+		if (handler->idiag_get_aux(sk, net_admin, skb) < 0)
+			goto errout;
+
 	if (sk->sk_state < TCP_TIME_WAIT) {
 		union tcp_cc_info info;
 		size_t sz = 0;
@@ -452,13 +466,14 @@ int inet_diag_dump_one_icsk(struct inet_hashinfo *hashinfo,
 	struct net *net = sock_net(in_skb->sk);
 	struct sk_buff *rep;
 	struct sock *sk;
+	bool net_admin = netlink_net_capable(in_skb, CAP_NET_ADMIN);
 	int err;
 
 	sk = inet_diag_find_one_icsk(net, hashinfo, req);
 	if (IS_ERR(sk))
 		return PTR_ERR(sk);
 
-	rep = nlmsg_new(inet_sk_attr_size(), GFP_KERNEL);
+	rep = nlmsg_new(inet_sk_attr_size(sk, req, net_admin), GFP_KERNEL);
 	if (!rep) {
 		err = -ENOMEM;
 		goto out;
@@ -467,8 +482,7 @@ int inet_diag_dump_one_icsk(struct inet_hashinfo *hashinfo,
 	err = sk_diag_fill(sk, rep, req,
 			   sk_user_ns(NETLINK_CB(in_skb).sk),
 			   NETLINK_CB(in_skb).portid,
-			   nlh->nlmsg_seq, 0, nlh,
-			   netlink_net_capable(in_skb, CAP_NET_ADMIN));
+			   nlh->nlmsg_seq, 0, nlh, net_admin);
 	if (err < 0) {
 		WARN_ON(err == -EMSGSIZE);
 		nlmsg_free(rep);
-- 
2.14.1

[PATCH net-next v2 2/2] tcp_diag: report TCP MD5 signing keys and addresses

[Ivan Delalande]

Report TCP MD5 (RFC2385) signing keys, addresses and address prefixes to
processes with CAP_NET_ADMIN requesting INET_DIAG_INFO. Currently it is
not possible to retrieve these from the kernel once they have been
configured on sockets.

Signed-off-by: Ivan Delalande <colona@arista.com>
---
 include/uapi/linux/inet_diag.h |   1 +
 net/ipv4/tcp_diag.c            | 112 ++++++++++++++++++++++++++++++++++++++---
 2 files changed, 107 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
index 678496897a68..f52ff62bfabe 100644
--- a/include/uapi/linux/inet_diag.h
+++ b/include/uapi/linux/inet_diag.h
@@ -143,6 +143,7 @@ enum {
 	INET_DIAG_MARK,
 	INET_DIAG_BBRINFO,
 	INET_DIAG_CLASS_ID,
+	INET_DIAG_MD5SIG,
 	__INET_DIAG_MAX,
 };
 
diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index a748c74aa8b7..99c54b765921 100644
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -16,6 +16,7 @@
 
 #include <linux/tcp.h>
 
+#include <net/netlink.h>
 #include <net/tcp.h>
 
 static void tcp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
@@ -36,6 +37,103 @@ static void tcp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
 		tcp_get_info(sk, info);
 }
 
+#ifdef CONFIG_TCP_MD5SIG
+static void inet_diag_md5sig_fill(struct tcp_md5sig *info,
+				  const struct tcp_md5sig_key *key)
+{
+	#if IS_ENABLED(CONFIG_IPV6)
+	if (key->family == AF_INET6) {
+		struct sockaddr_in6 *sin6 =
+			(struct sockaddr_in6 *)&info->tcpm_addr;
+
+		memcpy(&sin6->sin6_addr, &key->addr.a6,
+		       sizeof(struct in6_addr));
+	} else
+	#endif
+	{
+		struct sockaddr_in *sin =
+			(struct sockaddr_in *)&info->tcpm_addr;
+
+		memcpy(&sin->sin_addr, &key->addr.a4, sizeof(struct in_addr));
+	}
+
+	info->tcpm_addr.ss_family = key->family;
+	info->tcpm_prefixlen = key->prefixlen;
+	info->tcpm_keylen = key->keylen;
+	memcpy(info->tcpm_key, key->key, key->keylen);
+}
+
+static int inet_diag_put_md5sig(struct sk_buff *skb,
+				const struct tcp_md5sig_info *md5sig)
+{
+	const struct tcp_md5sig_key *key;
+	struct nlattr *attr;
+	struct tcp_md5sig *info;
+	int md5sig_count = 0;
+
+	hlist_for_each_entry_rcu(key, &md5sig->head, node)
+		md5sig_count++;
+
+	attr = nla_reserve(skb, INET_DIAG_MD5SIG,
+			   md5sig_count * sizeof(struct tcp_md5sig));
+	if (!attr)
+		return -EMSGSIZE;
+
+	info = nla_data(attr);
+	hlist_for_each_entry_rcu(key, &md5sig->head, node) {
+		inet_diag_md5sig_fill(info, key);
+		info++;
+	}
+
+	return 0;
+}
+#endif
+
+static int tcp_diag_get_aux(struct sock *sk, bool net_admin,
+			    struct sk_buff *skb)
+{
+#ifdef CONFIG_TCP_MD5SIG
+	if (net_admin) {
+		struct tcp_md5sig_info *md5sig;
+		int err = 0;
+
+		lock_sock(sk);
+		rcu_read_lock();
+		md5sig = rcu_dereference(tcp_sk(sk)->md5sig_info);
+		if (md5sig)
+			err = inet_diag_put_md5sig(skb, md5sig);
+		rcu_read_unlock();
+		release_sock(sk);
+		if (err < 0)
+			return err;
+	}
+#endif
+
+	return 0;
+}
+
+static size_t tcp_diag_get_aux_size(struct sock *sk, bool net_admin)
+{
+	size_t size = 0;
+
+#ifdef CONFIG_TCP_MD5SIG
+	if (sk_fullsock(sk)) {
+		const struct tcp_md5sig_info *md5sig;
+		const struct tcp_md5sig_key *key;
+
+		rcu_read_lock();
+		md5sig = rcu_dereference(tcp_sk(sk)->md5sig_info);
+		if (md5sig) {
+			hlist_for_each_entry_rcu(key, &md5sig->head, node)
+				size += sizeof(struct tcp_md5sig);
+		}
+		rcu_read_unlock();
+	}
+#endif
+
+	return size;
+}
+
 static void tcp_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
 			  const struct inet_diag_req_v2 *r, struct nlattr *bc)
 {
@@ -68,13 +166,15 @@ static int tcp_diag_destroy(struct sk_buff *in_skb,
 #endif
 
 static const struct inet_diag_handler tcp_diag_handler = {
-	.dump		 = tcp_diag_dump,
-	.dump_one	 = tcp_diag_dump_one,
-	.idiag_get_info	 = tcp_diag_get_info,
-	.idiag_type	 = IPPROTO_TCP,
-	.idiag_info_size = sizeof(struct tcp_info),
+	.dump			= tcp_diag_dump,
+	.dump_one		= tcp_diag_dump_one,
+	.idiag_get_info		= tcp_diag_get_info,
+	.idiag_get_aux		= tcp_diag_get_aux,
+	.idiag_get_aux_size	= tcp_diag_get_aux_size,
+	.idiag_type		= IPPROTO_TCP,
+	.idiag_info_size	= sizeof(struct tcp_info),
 #ifdef CONFIG_INET_DIAG_DESTROY
-	.destroy	 = tcp_diag_destroy,
+	.destroy		= tcp_diag_destroy,
 #endif
 };
 
-- 
2.14.1

Re: [PATCH net-next v2 2/2] tcp_diag: report TCP MD5 signing keys and addresses

[Eric Dumazet]

On Fri, 2017-08-25 at 18:53 -0700, Ivan Delalande wrote:
> Report TCP MD5 (RFC2385) signing keys, addresses and address prefixes to
> processes with CAP_NET_ADMIN requesting INET_DIAG_INFO. Currently it is
> not possible to retrieve these from the kernel once they have been
> configured on sockets.

...

> +static int inet_diag_put_md5sig(struct sk_buff *skb,
> +				const struct tcp_md5sig_info *md5sig)
> +{
> +	const struct tcp_md5sig_key *key;
> +	struct nlattr *attr;
> +	struct tcp_md5sig *info;
> +	int md5sig_count = 0;
> +
> +	hlist_for_each_entry_rcu(key, &md5sig->head, node)
> +		md5sig_count++;
> +
> +	attr = nla_reserve(skb, INET_DIAG_MD5SIG,
> +			   md5sig_count * sizeof(struct tcp_md5sig));
> +	if (!attr)
> +		return -EMSGSIZE;
> +
> +	info = nla_data(attr);
> +	hlist_for_each_entry_rcu(key, &md5sig->head, node) {
> +		inet_diag_md5sig_fill(info, key);
> +		info++;
> +	}
> +
> +	return 0;
> +}
> +#endif

Unless I missed something, I am sure I gave a feedback on this function
already :/

Re: [PATCH net-next v2 2/2] tcp_diag: report TCP MD5 signing keys and addresses

[Ivan Delalande]

On Fri, Aug 25, 2017 at 08:41:25PM -0700, Eric Dumazet wrote:
> On Fri, 2017-08-25 at 18:53 -0700, Ivan Delalande wrote:
> > Report TCP MD5 (RFC2385) signing keys, addresses and address prefixes to
> > processes with CAP_NET_ADMIN requesting INET_DIAG_INFO. Currently it is
> > not possible to retrieve these from the kernel once they have been
> > configured on sockets.
> 
> ...
> 
> > +static int inet_diag_put_md5sig(struct sk_buff *skb,
> > +				const struct tcp_md5sig_info *md5sig)
> > +{
> > +	const struct tcp_md5sig_key *key;
> > +	struct nlattr *attr;
> > +	struct tcp_md5sig *info;
> > +	int md5sig_count = 0;
> > +
> > +	hlist_for_each_entry_rcu(key, &md5sig->head, node)
> > +		md5sig_count++;
> > +
> > +	attr = nla_reserve(skb, INET_DIAG_MD5SIG,
> > +			   md5sig_count * sizeof(struct tcp_md5sig));
> > +	if (!attr)
> > +		return -EMSGSIZE;
> > +
> > +	info = nla_data(attr);
> > +	hlist_for_each_entry_rcu(key, &md5sig->head, node) {
> > +		inet_diag_md5sig_fill(info, key);
> > +		info++;
> > +	}
> > +
> > +	return 0;
> > +}
> > +#endif
> 
> Unless I missed something, I am sure I gave a feedback on this function
> already :/

Sorry, I probably should have detailed my changes. I tried to address
this by locking the whole socket in the caller, tcp_diag_get_aux, just
outside of the rcu_read_lock. Would this work here, or do you see a
better way?

Thanks for your feedback,
-- 
Ivan Delalande
Arista Networks

Re: [PATCH net-next v2 2/2] tcp_diag: report TCP MD5 signing keys and addresses

[Eric Dumazet]

On Sat, 2017-08-26 at 07:53 +0200, Ivan Delalande wrote:

> 
> Sorry, I probably should have detailed my changes. I tried to address
> this by locking the whole socket in the caller, tcp_diag_get_aux, just
> outside of the rcu_read_lock. Would this work here, or do you see a
> better way?
> 

locking the socket is problematic.

It is already done in tcp_get_info() since linux-4.10 and unfortunately
it added unreasonable stall when a socket is flooded with tiny SACK
messages (socket backlog is huge)

People are now making tcp_rmem and tcp_wmem much bigger to allow BBR
flows to reach line rate on very long distance communications.

We are working to make tcp_rack_mark_lost() not having O(N) behavior,
but it is not done yet.


I would stick to RCU, but add sanity checks, so that _if_ the list is
different on the second RCU list traversal, you make sure :

1) We do not try to put more data in the reserved space

2) We memset(ptr, 0, remaining) the remaining space if we found less
entries in the 2nd loop.