netdev - [PATCH net] packet: validate msg

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Message-Id: <20190426192735.145633-1-willemdebruijn.kernel@gmail.com>
Date:   Fri, 26 Apr 2019 15:27:35 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, David.Laight@...lab.com, idosch@...sch.org,
        Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH net] packet: validate msg_namelen in send directly

From: Willem de Bruijn <willemb@...gle.com>

Packet sockets in datagram mode take a destination address. Verify its
length before passing to dev_hard_header.

Prior to 2.6.14-rc3, the send code ignored sll_halen. This is
established behavior. Directly compare msg_namelen to dev->addr_len.

Fixes: 6b8d95f1795c4 ("packet: validate address length if non-zero")
Suggested-by: David Laight <David.Laight@...lab.com>
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
 net/packet/af_packet.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 9419c5cf4de5e..13301e36b4a28 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2624,10 +2624,13 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
 						sll_addr)))
 			goto out;
 		proto	= saddr->sll_protocol;
-		addr	= saddr->sll_halen ? saddr->sll_addr : NULL;
 		dev = dev_get_by_index(sock_net(&po->sk), saddr->sll_ifindex);
-		if (addr && dev && saddr->sll_halen < dev->addr_len)
-			goto out_put;
+		if (po->sk.sk_socket->type == SOCK_DGRAM) {
+			addr = saddr->sll_addr;
+			if (dev && msg->msg_namelen < dev->addr_len +
+					offsetof(struct sockaddr_ll, sll_addr))
+				goto out_put;
+		}
 	}
 
 	err = -ENXIO;
@@ -2824,10 +2827,13 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
 		if (msg->msg_namelen < (saddr->sll_halen + offsetof(struct sockaddr_ll, sll_addr)))
 			goto out;
 		proto	= saddr->sll_protocol;
-		addr	= saddr->sll_halen ? saddr->sll_addr : NULL;
 		dev = dev_get_by_index(sock_net(sk), saddr->sll_ifindex);
-		if (addr && dev && saddr->sll_halen < dev->addr_len)
-			goto out_unlock;
+		if (sock->type == SOCK_DGRAM) {
+			addr = saddr->sll_addr;
+			if (dev && msg->msg_namelen < dev->addr_len +
+					offsetof(struct sockaddr_ll, sll_addr))
+				goto out_unlock;
+		}
 	}
 
 	err = -ENXIO;
-- 
2.21.0.593.g511ec345e18-goog