[PATCH 4.19 14/23] packet: validate msg_namelen in send directly

[Greg Kroah-Hartman]

From: Willem de Bruijn <will...@google.com>

[ Upstream commit 486efdc8f6ce802b27e15921d2353cc740c55451 ]

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.lai...@aculab.com>
Signed-off-by: Willem de Bruijn <will...@google.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 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
@@ -2603,8 +2603,8 @@ 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;
        void *data;
        int len_sum = 0;
        int status = TP_STATUS_AVAILABLE;
@@ -2615,7 +2615,6 @@ 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))
@@ -2625,10 +2624,13 @@ 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;
@@ -2800,7 +2802,7 @@ 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 sockcm_cookie sockc;
        struct virtio_net_hdr vnet_hdr = { 0 };
@@ -2817,7 +2819,6 @@ 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))
@@ -2825,10 +2826,13 @@ 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;