linux-kernel - [PATCH 3.16 119/157] packet: validate msg

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Message-ID: <lsq.1565469607.152150829@decadent.org.uk>
Date:   Sat, 10 Aug 2019 21:40:07 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "David Laight" <David.Laight@...lab.com>,
        "Willem de Bruijn" <willemb@...gle.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.16 119/157] packet: validate msg_namelen in send directly

3.16.72-rc1 review patch.  If anyone has any objections, please let me know.

------------------

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

commit 486efdc8f6ce802b27e15921d2353cc740c55451 upstream.

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.

Change v1->v2: initialize addr in all paths

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>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/packet/af_packet.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2278,8 +2278,8 @@ static int tpacket_snd(struct packet_soc
 	void *ph;
 	DECLARE_SOCKADDR(struct sockaddr_ll *, saddr, msg->msg_name);
 	bool need_wait = !(msg->msg_flags & MSG_DONTWAIT);
+	unsigned char *addr = NULL;
 	int tp_len, size_max;
-	unsigned char *addr;
 	int len_sum = 0;
 	int status = TP_STATUS_AVAILABLE;
 	int hlen, tlen;
@@ -2289,7 +2289,6 @@ static int tpacket_snd(struct packet_soc
 	if (likely(saddr == NULL)) {
 		dev	= packet_cached_dev_get(po);
 		proto	= po->num;
-		addr	= NULL;
 	} else {
 		err = -EINVAL;
 		if (msg->msg_namelen < sizeof(struct sockaddr_ll))
@@ -2299,10 +2298,13 @@ static int tpacket_snd(struct packet_soc
 						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) {
+			if (dev && msg->msg_namelen < dev->addr_len +
+				   offsetof(struct sockaddr_ll, sll_addr))
+				goto out_put;
+			addr = saddr->sll_addr;
+		}
 	}
 
 	err = -ENXIO;
@@ -2435,7 +2437,7 @@ static int packet_snd(struct socket *soc
 	struct sk_buff *skb;
 	struct net_device *dev;
 	__be16 proto;
-	unsigned char *addr;
+	unsigned char *addr = NULL;
 	int err, reserve = 0;
 	struct virtio_net_hdr vnet_hdr = { 0 };
 	int offset = 0;
@@ -2453,7 +2455,6 @@ static int packet_snd(struct socket *soc
 	if (likely(saddr == NULL)) {
 		dev	= packet_cached_dev_get(po);
 		proto	= po->num;
-		addr	= NULL;
 	} else {
 		err = -EINVAL;
 		if (msg->msg_namelen < sizeof(struct sockaddr_ll))
@@ -2461,10 +2462,13 @@ static int packet_snd(struct socket *soc
 		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) {
+			if (dev && msg->msg_namelen < dev->addr_len +
+				   offsetof(struct sockaddr_ll, sll_addr))
+				goto out_unlock;
+			addr = saddr->sll_addr;
+		}
 	}
 
 	err = -ENXIO;