net: ip, diag -- Add diag interface for raw sockets

In criu we are actively using diag interface to collect sockets
present in the system when dumping applications. And while for
unix, tcp, udp[lite], packet, netlink it works as expected,
the raw sockets do not have. Thus add it.

v2:
 - add missing sock_put calls in raw_diag_dump_one (by eric.dumazet@)
 - implement @destroy for diag requests (by dsa@)

v3:
 - add export of raw_abort for IPv6 (by dsa@)
 - pass net-admin flag into inet_sk_diag_fill due to
   changes in net-next branch (by dsa@)

v4:
 - use @pad in struct inet_diag_req_v2 for raw socket
   protocol specification: raw module carries sockets
   which may have custom protocol passed from socket()
   syscall and sole @sdiag_protocol is not enough to
   match underlied ones
 - start reporting protocol specifed in socket() call
   when sockets are raw ones for the same reason: user
   space tools like ss may parse this attribute and use
   it for socket matching

v5 (by eric.dumazet@):
 - use sock_hold in raw_sock_get instead of atomic_inc,
   we're holding (raw_v4_hashinfo|raw_v6_hashinfo)->lock
   when looking up so counter won't be zero here.

v6:
 - use sdiag_raw_protocol() helper which will access @pad
   structure used for raw sockets protocol specification:
   we can't simply rename this member without breaking uapi

v7:
 - sine sdiag_raw_protocol() helper is not suitable for
   uapi lets rather make an alias structure with proper
   names. __check_inet_diag_req_raw helper will catch
   if any of structure unintentionally changed.

CC: David S. Miller <davem@davemloft.net>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: David Ahern <dsa@cumulusnetworks.com>
CC: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
CC: James Morris <jmorris@namei.org>
CC: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
CC: Patrick McHardy <kaber@trash.net>
CC: Andrey Vagin <avagin@openvz.org>
CC: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 261 insertions, 0 deletions

diff --git a/net/ipv4/raw_diag.c b/net/ipv4/raw_diag.c
new file mode 100644
index 000000000000..ef3bea061b75
--- /dev/null
+++ b/net/ipv4/raw_diag.c
@@ -0,0 +1,261 @@
+#include <linux/module.h>
+
+#include <linux/inet_diag.h>
+#include <linux/sock_diag.h>
+
+#include <net/raw.h>
+#include <net/rawv6.h>
+
+#ifdef pr_fmt
+# undef pr_fmt
+#endif
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+static struct raw_hashinfo *
+raw_get_hashinfo(const struct inet_diag_req_v2 *r)
+{
+	if (r->sdiag_family == AF_INET) {
+		return &raw_v4_hashinfo;
+#if IS_ENABLED(CONFIG_IPV6)
+	} else if (r->sdiag_family == AF_INET6) {
+		return &raw_v6_hashinfo;
+#endif
+	} else {
+		pr_warn_once("Unexpected inet family %d\n",
+			     r->sdiag_family);
+		WARN_ON_ONCE(1);
+		return ERR_PTR(-EINVAL);
+	}
+}
+
+/*
+ * Due to requirement of not breaking user API we can't simply
+ * rename @pad field in inet_diag_req_v2 structure, instead
+ * use helper to figure it out.
+ */
+
+static struct sock *raw_lookup(struct net *net, struct sock *from,
+			       const struct inet_diag_req_v2 *req)
+{
+	struct inet_diag_req_raw *r = (void *)req;
+	struct sock *sk = NULL;
+
+	if (r->sdiag_family == AF_INET)
+		sk = __raw_v4_lookup(net, from, r->sdiag_raw_protocol,
+				     r->id.idiag_dst[0],
+				     r->id.idiag_src[0],
+				     r->id.idiag_if);
+#if IS_ENABLED(CONFIG_IPV6)
+	else
+		sk = __raw_v6_lookup(net, from, r->sdiag_raw_protocol,
+				     (const struct in6_addr *)r->id.idiag_src,
+				     (const struct in6_addr *)r->id.idiag_dst,
+				     r->id.idiag_if);
+#endif
+	return sk;
+}
+
+static struct sock *raw_sock_get(struct net *net, const struct inet_diag_req_v2 *r)
+{
+	struct raw_hashinfo *hashinfo = raw_get_hashinfo(r);
+	struct sock *sk = NULL, *s;
+	int slot;
+
+	if (IS_ERR(hashinfo))
+		return ERR_CAST(hashinfo);
+
+	read_lock(&hashinfo->lock);
+	for (slot = 0; slot < RAW_HTABLE_SIZE; slot++) {
+		sk_for_each(s, &hashinfo->ht[slot]) {
+			sk = raw_lookup(net, s, r);
+			if (sk) {
+				/*
+				 * Grab it and keep until we fill
+				 * diag meaage to be reported, so
+				 * caller should call sock_put then.
+				 * We can do that because we're keeping
+				 * hashinfo->lock here.
+				 */
+				sock_hold(sk);
+				break;
+			}
+		}
+	}
+	read_unlock(&hashinfo->lock);
+
+	return sk ? sk : ERR_PTR(-ENOENT);
+}
+
+static int raw_diag_dump_one(struct sk_buff *in_skb,
+			     const struct nlmsghdr *nlh,
+			     const struct inet_diag_req_v2 *r)
+{
+	struct net *net = sock_net(in_skb->sk);
+	struct sk_buff *rep;
+	struct sock *sk;
+	int err;
+
+	sk = raw_sock_get(net, r);
+	if (IS_ERR(sk))
+		return PTR_ERR(sk);
+
+	rep = nlmsg_new(sizeof(struct inet_diag_msg) +
+			sizeof(struct inet_diag_meminfo) + 64,
+			GFP_KERNEL);
+	if (!rep) {
+		sock_put(sk);
+		return -ENOMEM;
+	}
+
+	err = inet_sk_diag_fill(sk, NULL, rep, r,
+				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));
+	sock_put(sk);
+
+	if (err < 0) {
+		kfree_skb(rep);
+		return err;
+	}
+
+	err = netlink_unicast(net->diag_nlsk, rep,
+			      NETLINK_CB(in_skb).portid,
+			      MSG_DONTWAIT);
+	if (err > 0)
+		err = 0;
+	return err;
+}
+
+static int sk_diag_dump(struct sock *sk, struct sk_buff *skb,
+			struct netlink_callback *cb,
+			const struct inet_diag_req_v2 *r,
+			struct nlattr *bc, bool net_admin)
+{
+	if (!inet_diag_bc_sk(bc, sk))
+		return 0;
+
+	return inet_sk_diag_fill(sk, NULL, skb, r,
+				 sk_user_ns(NETLINK_CB(cb->skb).sk),
+				 NETLINK_CB(cb->skb).portid,
+				 cb->nlh->nlmsg_seq, NLM_F_MULTI,
+				 cb->nlh, net_admin);
+}
+
+static void raw_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
+			  const struct inet_diag_req_v2 *r, struct nlattr *bc)
+{
+	bool net_admin = netlink_net_capable(cb->skb, CAP_NET_ADMIN);
+	struct raw_hashinfo *hashinfo = raw_get_hashinfo(r);
+	struct net *net = sock_net(skb->sk);
+	int num, s_num, slot, s_slot;
+	struct sock *sk = NULL;
+
+	if (IS_ERR(hashinfo))
+		return;
+
+	s_slot = cb->args[0];
+	num = s_num = cb->args[1];
+
+	read_lock(&hashinfo->lock);
+	for (slot = s_slot; slot < RAW_HTABLE_SIZE; s_num = 0, slot++) {
+		num = 0;
+
+		sk_for_each(sk, &hashinfo->ht[slot]) {
+			struct inet_sock *inet = inet_sk(sk);
+
+			if (!net_eq(sock_net(sk), net))
+				continue;
+			if (num < s_num)
+				goto next;
+			if (sk->sk_family != r->sdiag_family)
+				goto next;
+			if (r->id.idiag_sport != inet->inet_sport &&
+			    r->id.idiag_sport)
+				goto next;
+			if (r->id.idiag_dport != inet->inet_dport &&
+			    r->id.idiag_dport)
+				goto next;
+			if (sk_diag_dump(sk, skb, cb, r, bc, net_admin) < 0)
+				goto out_unlock;
+next:
+			num++;
+		}
+	}
+
+out_unlock:
+	read_unlock(&hashinfo->lock);
+
+	cb->args[0] = slot;
+	cb->args[1] = num;
+}
+
+static void raw_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
+			      void *info)
+{
+	r->idiag_rqueue = sk_rmem_alloc_get(sk);
+	r->idiag_wqueue = sk_wmem_alloc_get(sk);
+}
+
+#ifdef CONFIG_INET_DIAG_DESTROY
+static int raw_diag_destroy(struct sk_buff *in_skb,
+			    const struct inet_diag_req_v2 *r)
+{
+	struct net *net = sock_net(in_skb->sk);
+	struct sock *sk;
+
+	sk = raw_sock_get(net, r);
+	if (IS_ERR(sk))
+		return PTR_ERR(sk);
+	return sock_diag_destroy(sk, ECONNABORTED);
+}
+#endif
+
+static const struct inet_diag_handler raw_diag_handler = {
+	.dump			= raw_diag_dump,
+	.dump_one		= raw_diag_dump_one,
+	.idiag_get_info		= raw_diag_get_info,
+	.idiag_type		= IPPROTO_RAW,
+	.idiag_info_size	= 0,
+#ifdef CONFIG_INET_DIAG_DESTROY
+	.destroy		= raw_diag_destroy,
+#endif
+};
+
+static void __always_unused __check_inet_diag_req_raw(void)
+{
+	/*
+	 * Make sure the two structures are identical,
+	 * except the @pad field.
+	 */
+#define __offset_mismatch(m1, m2)			\
+	(offsetof(struct inet_diag_req_v2, m1) !=	\
+	 offsetof(struct inet_diag_req_raw, m2))
+
+	BUILD_BUG_ON(sizeof(struct inet_diag_req_v2) !=
+		     sizeof(struct inet_diag_req_raw));
+	BUILD_BUG_ON(__offset_mismatch(sdiag_family, sdiag_family));
+	BUILD_BUG_ON(__offset_mismatch(sdiag_protocol, sdiag_protocol));
+	BUILD_BUG_ON(__offset_mismatch(idiag_ext, idiag_ext));
+	BUILD_BUG_ON(__offset_mismatch(pad, sdiag_raw_protocol));
+	BUILD_BUG_ON(__offset_mismatch(idiag_states, idiag_states));
+	BUILD_BUG_ON(__offset_mismatch(id, id));
+#undef __offset_mismatch
+}
+
+static int __init raw_diag_init(void)
+{
+	return inet_diag_register(&raw_diag_handler);
+}
+
+static void __exit raw_diag_exit(void)
+{
+	inet_diag_unregister(&raw_diag_handler);
+}
+
+module_init(raw_diag_init);
+module_exit(raw_diag_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 2-255 /* AF_INET - IPPROTO_RAW */);
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 10-255 /* AF_INET6 - IPPROTO_RAW */);