net: diag: allow socket bytecode filters to match socket marks

This allows a privileged process to filter by socket mark when
dumping sockets via INET_DIAG_BY_FAMILY. This is useful on
systems that use mark-based routing such as Android.

The ability to filter socket marks requires CAP_NET_ADMIN, which
is consistent with other privileged operations allowed by the
SOCK_DIAG interface such as the ability to destroy sockets and
the ability to inspect BPF filters attached to packet sockets.

[backport of net-next a52e95abf772b43c9226e9a72d3c1353903ba96f]

Change-Id: If4609026882ef283a619b8bf24c0127f1f18ce6a
Tested: https://android-review.googlesource.com/261350
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Acked-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 29 insertions, 3 deletions

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 2e6bee08c..d60accaa7 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -49,6 +49,7 @@ struct inet_diag_entry {
 	struct in6_addr daddr_storage;	/* for IPv4-mapped-IPv6 addresses */
 #endif
 	u32 ifindex;
+	u32 mark;
 };
 
 static DEFINE_MUTEX(inet_diag_table_mutex);
@@ -532,6 +533,14 @@ static int inet_diag_bc_run(const struct nlattr *_bc,
 				yes = 0;
 			break;
 		}
+		case INET_DIAG_BC_MARK_COND: {
+			struct inet_diag_markcond *cond;
+
+			cond = (struct inet_diag_markcond *)(op + 1);
+			if ((entry->mark & cond->mask) != cond->mark)
+				yes = 0;
+			break;
+		}
 		}
 
 		if (yes) {
@@ -570,6 +579,7 @@ int inet_diag_bc_sk(const struct nlattr *bc, struct sock *sk)
 	entry.dport = ntohs(inet->inet_dport);
 	entry.ifindex = sk->sk_bound_dev_if;
 	entry.userlocks = sk->sk_userlocks;
+	entry.mark = sk->sk_mark;
 
 	return inet_diag_bc_run(bc, &entry);
 }
@@ -652,8 +662,17 @@ static inline bool valid_port_comparison(const struct inet_diag_bc_op *op,
 	return true;
 }
 
-static int inet_diag_bc_audit(const struct nlattr *attr)
+static bool valid_markcond(const struct inet_diag_bc_op *op, int len,
+			   int *min_len)
+{
+	*min_len += sizeof(struct inet_diag_markcond);
+	return len >= *min_len;
+}
+
+static int inet_diag_bc_audit(const struct nlattr *attr,
+			      const struct sk_buff *skb)
 {
+	bool net_admin = netlink_net_capable(skb, CAP_NET_ADMIN);
 	const void *bytecode, *bc;
 	int bytecode_len, len;
 
@@ -685,6 +704,12 @@ static int inet_diag_bc_audit(const struct nlattr *attr)
 			if (!valid_port_comparison(bc, len, &min_len))
 				return -EINVAL;
 			break;
+		case INET_DIAG_BC_MARK_COND:
+			if (!net_admin)
+				return -EPERM;
+			if (!valid_markcond(bc, len, &min_len))
+				return -EINVAL;
+			break;
 		case INET_DIAG_BC_AUTO:
 		case INET_DIAG_BC_JMP:
 		case INET_DIAG_BC_NOP:
@@ -751,6 +776,7 @@ static int inet_twsk_diag_dump(struct inet_timewait_sock *tw,
 		entry.sport = tw->tw_num;
 		entry.dport = ntohs(tw->tw_dport);
 		entry.userlocks = 0;
+		entry.mark = 0;
 
 		if (!inet_diag_bc_run(bc, &entry))
 			return 0;
@@ -1173,7 +1199,7 @@ static int inet_diag_rcv_msg_compat(struct sk_buff *skb, struct nlmsghdr *nlh)
 
 			attr = nlmsg_find_attr(nlh, hdrlen,
 					       INET_DIAG_REQ_BYTECODE);
-			err = inet_diag_bc_audit(attr);
+			err = inet_diag_bc_audit(attr, skb);
 			if (err)
 				return err;
 		}
@@ -1204,7 +1230,7 @@ static int inet_diag_handler_cmd(struct sk_buff *skb, struct nlmsghdr *h)
 
 			attr = nlmsg_find_attr(h, hdrlen,
 					       INET_DIAG_REQ_BYTECODE);
-			err = inet_diag_bc_audit(attr);
+			err = inet_diag_bc_audit(attr, skb);
 			if (err)
 				return err;
 		}