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 a52e95abf772 ("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.

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

1 files changed, 14 insertions, 6 deletions

diff --git a/net/sctp/sctp_diag.c b/net/sctp/sctp_diag.c
index f3508aa..807158e3 100644
--- a/net/sctp/sctp_diag.c
+++ b/net/sctp/sctp_diag.c
@@ -106,7 +106,8 @@ static int inet_sctp_diag_fill(struct sock *sk, struct sctp_association *asoc,
 			       const struct inet_diag_req_v2 *req,
 			       struct user_namespace *user_ns,
 			       int portid, u32 seq, u16 nlmsg_flags,
-			       const struct nlmsghdr *unlh)
+			       const struct nlmsghdr *unlh,
+			       bool net_admin)
 {
 	struct sctp_endpoint *ep = sctp_sk(sk)->ep;
 	struct list_head *addr_list;
@@ -133,7 +134,7 @@ static int inet_sctp_diag_fill(struct sock *sk, struct sctp_association *asoc,
 		r->idiag_retrans = 0;
 	}
 
-	if (inet_diag_msg_attrs_fill(sk, skb, r, ext, user_ns))
+	if (inet_diag_msg_attrs_fill(sk, skb, r, ext, user_ns, net_admin))
 		goto errout;
 
 	if (ext & (1 << (INET_DIAG_SKMEMINFO - 1))) {
@@ -203,6 +204,7 @@ struct sctp_comm_param {
 	struct netlink_callback *cb;
 	const struct inet_diag_req_v2 *r;
 	const struct nlmsghdr *nlh;
+	bool net_admin;
 };
 
 static size_t inet_assoc_attr_size(struct sctp_association *asoc)
@@ -219,6 +221,7 @@ static size_t inet_assoc_attr_size(struct sctp_association *asoc)
 		+ 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(addrlen * asoc->peer.transport_count)
 		+ nla_total_size(addrlen * addrcnt)
 		+ nla_total_size(sizeof(struct inet_diag_meminfo))
@@ -256,7 +259,8 @@ static int sctp_tsp_dump_one(struct sctp_transport *tsp, void *p)
 	err = inet_sctp_diag_fill(sk, assoc, 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,
+				  commp->net_admin);
 	release_sock(sk);
 	if (err < 0) {
 		WARN_ON(err == -EMSGSIZE);
@@ -310,7 +314,8 @@ static int sctp_tsp_dump(struct sctp_transport *tsp, void *p)
 					sk_user_ns(NETLINK_CB(cb->skb).sk),
 					NETLINK_CB(cb->skb).portid,
 					cb->nlh->nlmsg_seq,
-					NLM_F_MULTI, cb->nlh) < 0) {
+					NLM_F_MULTI, cb->nlh,
+					commp->net_admin) < 0) {
 			cb->args[3] = 1;
 			err = 2;
 			goto release;
@@ -320,7 +325,8 @@ static int sctp_tsp_dump(struct sctp_transport *tsp, void *p)
 		if (inet_sctp_diag_fill(sk, assoc, skb, r,
 					sk_user_ns(NETLINK_CB(cb->skb).sk),
 					NETLINK_CB(cb->skb).portid,
-					cb->nlh->nlmsg_seq, 0, cb->nlh) < 0) {
+					cb->nlh->nlmsg_seq, 0, cb->nlh,
+					commp->net_admin) < 0) {
 			err = 2;
 			goto release;
 		}
@@ -375,7 +381,7 @@ static int sctp_ep_dump(struct sctp_endpoint *ep, void *p)
 				sk_user_ns(NETLINK_CB(cb->skb).sk),
 				NETLINK_CB(cb->skb).portid,
 				cb->nlh->nlmsg_seq, NLM_F_MULTI,
-				cb->nlh) < 0) {
+				cb->nlh, commp->net_admin) < 0) {
 		err = 2;
 		goto out;
 	}
@@ -412,6 +418,7 @@ static int sctp_diag_dump_one(struct sk_buff *in_skb,
 		.skb = in_skb,
 		.r = req,
 		.nlh = nlh,
+		.net_admin = netlink_net_capable(in_skb, CAP_NET_ADMIN),
 	};
 
 	if (req->sdiag_family == AF_INET) {
@@ -447,6 +454,7 @@ static void sctp_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
 		.skb = skb,
 		.cb = cb,
 		.r = r,
+		.net_admin = netlink_net_capable(cb->skb, CAP_NET_ADMIN),
 	};
 
 	/* eps hashtable dumps