net: inet: diag: expose the socket mark to privileged processes.

This adds the capability for a process that has CAP_NET_ADMIN on
a socket to see the socket mark in socket dumps.

Commit a52e95abf7 ("net: diag: allow socket bytecode filters to
match socket marks") recently gave privileged processes the
ability to filter socket dumps based on mark. This patch is
complementary: it ensures that the mark is also passed to
userspace in the socket's netlink attributes.  It is useful for
tools like ss which display information about sockets.

[backport of net-next d545caca82]

Change-Id: I33336ed9c3ee3fb78fe05c4c47b7fd18c6e33ef1
Tested: https://android-review.googlesource.com/270210
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/inet_diag.h

@@ -37,7 +37,7 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
 		      struct sk_buff *skb, const struct inet_diag_req_v2 *req,
 		      struct user_namespace *user_ns,
 		      u32 pid, u32 seq, u16 nlmsg_flags,
-		      const struct nlmsghdr *unlh);
+		      const struct nlmsghdr *unlh, bool net_admin);
 void inet_diag_dump_icsk(struct inet_hashinfo *h, struct sk_buff *skb,
 			 struct netlink_callback *cb,
 			 const struct inet_diag_req_v2 *r,

include/uapi/linux/inet_diag.h

@@ -120,9 +120,13 @@ enum {
 	INET_DIAG_DCTCPINFO,
 	INET_DIAG_PROTOCOL,  /* response attribute only */
 	INET_DIAG_SKV6ONLY,
+	INET_DIAG_LOCALS,
+	INET_DIAG_PEERS,
+	INET_DIAG_PAD,
+	INET_DIAG_MARK,
 };
 
-#define INET_DIAG_MAX INET_DIAG_SKV6ONLY
+#define INET_DIAG_MAX INET_DIAG_MARK
 
 /* INET_DIAG_MEM */
 

net/ipv4/inet_diag.c

@@ -98,6 +98,7 @@ static size_t inet_sk_attr_size(void)
 		+ nla_total_size(1) /* INET_DIAG_SHUTDOWN */
 		+ nla_total_size(1) /* INET_DIAG_TOS */
 		+ nla_total_size(1) /* INET_DIAG_TCLASS */
+		+ nla_total_size(4) /* INET_DIAG_MARK */
 		+ nla_total_size(sizeof(struct inet_diag_meminfo))
 		+ nla_total_size(sizeof(struct inet_diag_msg))
 		+ nla_total_size(SK_MEMINFO_VARS * sizeof(u32))
@@ -110,7 +111,8 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
 		      struct sk_buff *skb, const struct inet_diag_req_v2 *req,
 		      struct user_namespace *user_ns,
 		      u32 portid, u32 seq, u16 nlmsg_flags,
-		      const struct nlmsghdr *unlh)
+		      const struct nlmsghdr *unlh,
+		      bool net_admin)
 {
 	const struct inet_sock *inet = inet_sk(sk);
 	const struct tcp_congestion_ops *ca_ops;
@@ -160,6 +162,9 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
 	}
 #endif
 
+	if (net_admin && nla_put_u32(skb, INET_DIAG_MARK, sk->sk_mark))
+		goto errout;
+
 	r->idiag_uid = from_kuid_munged(user_ns, sock_i_uid(sk));
 	r->idiag_inode = sock_i_ino(sk);
 
@@ -258,10 +263,11 @@ static int inet_csk_diag_fill(struct sock *sk,
 			      const struct inet_diag_req_v2 *req,
 			      struct user_namespace *user_ns,
 			      u32 portid, u32 seq, u16 nlmsg_flags,
-			      const struct nlmsghdr *unlh)
+			      const struct nlmsghdr *unlh,
+			      bool net_admin)
 {
-	return inet_sk_diag_fill(sk, inet_csk(sk), skb, req,
-				 user_ns, portid, seq, nlmsg_flags, unlh);
+	return inet_sk_diag_fill(sk, inet_csk(sk), skb, req, user_ns,
+				 portid, seq, nlmsg_flags, unlh, net_admin);
 }
 
 static int inet_twsk_diag_fill(struct sock *sk,
@@ -303,8 +309,9 @@ static int inet_twsk_diag_fill(struct sock *sk,
 
 static int inet_req_diag_fill(struct sock *sk, struct sk_buff *skb,
 			      u32 portid, u32 seq, u16 nlmsg_flags,
-			      const struct nlmsghdr *unlh)
+			      const struct nlmsghdr *unlh, bool net_admin)
 {
+	struct request_sock *reqsk = inet_reqsk(sk);
 	struct inet_diag_msg *r;
 	struct nlmsghdr *nlh;
 	long tmo;
@@ -318,7 +325,7 @@ static int inet_req_diag_fill(struct sock *sk, struct sk_buff *skb,
 	inet_diag_msg_common_fill(r, sk);
 	r->idiag_state = TCP_SYN_RECV;
 	r->idiag_timer = 1;
-	r->idiag_retrans = inet_reqsk(sk)->num_retrans;
+	r->idiag_retrans = reqsk->num_retrans;
 
 	BUILD_BUG_ON(offsetof(struct inet_request_sock, ir_cookie) !=
 		     offsetof(struct sock, sk_cookie));
@@ -330,6 +337,10 @@ static int inet_req_diag_fill(struct sock *sk, struct sk_buff *skb,
 	r->idiag_uid	= 0;
 	r->idiag_inode	= 0;
 
+	if (net_admin && nla_put_u32(skb, INET_DIAG_MARK,
+				     inet_rsk(reqsk)->ir_mark))
+		return -EMSGSIZE;
+
 	nlmsg_end(skb, nlh);
 	return 0;
 }
@@ -338,7 +349,7 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
 			const struct inet_diag_req_v2 *r,
 			struct user_namespace *user_ns,
 			u32 portid, u32 seq, u16 nlmsg_flags,
-			const struct nlmsghdr *unlh)
+			const struct nlmsghdr *unlh, bool net_admin)
 {
 	if (sk->sk_state == TCP_TIME_WAIT)
 		return inet_twsk_diag_fill(sk, skb, portid, seq,
@@ -346,10 +357,10 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
 
 	if (sk->sk_state == TCP_NEW_SYN_RECV)
 		return inet_req_diag_fill(sk, skb, portid, seq,
-					  nlmsg_flags, unlh);
+					  nlmsg_flags, unlh, net_admin);
 
 	return inet_csk_diag_fill(sk, skb, r, user_ns, portid, seq,
-				  nlmsg_flags, unlh);
+				  nlmsg_flags, unlh, net_admin);
 }
 
 struct sock *inet_diag_find_one_icsk(struct net *net,
@@ -416,7 +427,8 @@ 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);
+			   nlh->nlmsg_seq, 0, nlh,
+			   netlink_net_capable(in_skb, CAP_NET_ADMIN));
 	if (err < 0) {
 		WARN_ON(err == -EMSGSIZE);
 		nlmsg_free(rep);
@@ -777,7 +789,8 @@ static int inet_csk_diag_dump(struct sock *sk,
 			      struct sk_buff *skb,
 			      struct netlink_callback *cb,
 			      const struct inet_diag_req_v2 *r,
-			      const struct nlattr *bc)
+			      const struct nlattr *bc,
+			      bool net_admin)
 {
 	if (!inet_diag_bc_sk(bc, sk))
 		return 0;
@@ -785,7 +798,8 @@ static int inet_csk_diag_dump(struct sock *sk,
 	return inet_csk_diag_fill(sk, skb, r,
 				  sk_user_ns(NETLINK_CB(cb->skb).sk),
 				  NETLINK_CB(cb->skb).portid,
-				  cb->nlh->nlmsg_seq, NLM_F_MULTI, cb->nlh);
+				  cb->nlh->nlmsg_seq, NLM_F_MULTI, cb->nlh,
+				  net_admin);
 }
 
 static void twsk_build_assert(void)
@@ -821,6 +835,7 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
 	struct net *net = sock_net(skb->sk);
 	int i, num, s_i, s_num;
 	u32 idiag_states = r->idiag_states;
+	bool net_admin = netlink_net_capable(cb->skb, CAP_NET_ADMIN);
 
 	if (idiag_states & TCPF_SYN_RECV)
 		idiag_states |= TCPF_NEW_SYN_RECV;
@@ -862,7 +877,8 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
 				    cb->args[3] > 0)
 					goto next_listen;
 
-				if (inet_csk_diag_dump(sk, skb, cb, r, bc) < 0) {
+				if (inet_csk_diag_dump(sk, skb, cb, r,
+						       bc, net_admin) < 0) {
 					spin_unlock_bh(&ilb->lock);
 					goto done;
 				}
@@ -930,7 +946,7 @@ skip_listen_ht:
 					   sk_user_ns(NETLINK_CB(cb->skb).sk),
 					   NETLINK_CB(cb->skb).portid,
 					   cb->nlh->nlmsg_seq, NLM_F_MULTI,
-					   cb->nlh);
+					   cb->nlh, net_admin);
 			if (res < 0) {
 				spin_unlock_bh(lock);
 				goto done;

net/ipv4/udp_diag.c

@@ -20,7 +20,7 @@
 static int sk_diag_dump(struct sock *sk, struct sk_buff *skb,
 			struct netlink_callback *cb,
 			const struct inet_diag_req_v2 *req,
-			struct nlattr *bc)
+			struct nlattr *bc, bool net_admin)
 {
 	if (!inet_diag_bc_sk(bc, sk))
 		return 0;
@@ -28,7 +28,7 @@ static int sk_diag_dump(struct sock *sk, struct sk_buff *skb,
 	return inet_sk_diag_fill(sk, NULL, skb, req,
 			sk_user_ns(NETLINK_CB(cb->skb).sk),
 			NETLINK_CB(cb->skb).portid,
-			cb->nlh->nlmsg_seq, NLM_F_MULTI, cb->nlh);
+			cb->nlh->nlmsg_seq, NLM_F_MULTI, cb->nlh, net_admin);
 }
 
 static int udp_dump_one(struct udp_table *tbl, struct sk_buff *in_skb,
@@ -75,7 +75,8 @@ static int udp_dump_one(struct udp_table *tbl, struct sk_buff *in_skb,
 	err = inet_sk_diag_fill(sk, NULL, rep, req,
 			   sk_user_ns(NETLINK_CB(in_skb).sk),
 			   NETLINK_CB(in_skb).portid,
-			   nlh->nlmsg_seq, 0, nlh);
+			   nlh->nlmsg_seq, 0, nlh,
+			   netlink_net_capable(in_skb, CAP_NET_ADMIN));
 	if (err < 0) {
 		WARN_ON(err == -EMSGSIZE);
 		kfree_skb(rep);
@@ -98,6 +99,7 @@ static void udp_dump(struct udp_table *table, struct sk_buff *skb,
 {
 	int num, s_num, slot, s_slot;
 	struct net *net = sock_net(skb->sk);
+	bool net_admin = netlink_net_capable(cb->skb, CAP_NET_ADMIN);
 
 	s_slot = cb->args[0];
 	num = s_num = cb->args[1];
@@ -132,7 +134,7 @@ static void udp_dump(struct udp_table *table, struct sk_buff *skb,
 			    r->id.idiag_dport)
 				goto next;
 
-			if (sk_diag_dump(sk, skb, cb, r, bc) < 0) {
+			if (sk_diag_dump(sk, skb, cb, r, bc, net_admin) < 0) {
 				spin_unlock_bh(&hslot->lock);
 				goto done;
 			}